Evaluación del impacto de las estructuras de defensa costera sobre la biota marina. Efectos a nivel local, regional y trófico

Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b I Cover photo by Francisco Sedano Vera Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b II Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b III Laboratorio de Biología Marina Facultad de Biología Universidad de Sevilla EVALUACIÓN DEL IMPACTO DE LAS ESTRUCTURAS DE DEFENSA COSTERA SOBRE LA BIOTA MARINA. EFECTOS A NIVEL LOCAL, REGIONAL Y TRÓFICO. UNDERSTANDING THE IMPACT OF COASTAL DEFENCE STRUCTURES ON MARINE BIOTA. EFFECTS AT LOCAL, REGIONAL AND TROPHIC LEVEL. Tesis presentada para optar al título de Doctor con mención internacional por la Universidad de Sevilla. Francisco Sedano Vera Sevilla, septiembre de 2020 Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b IV Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b V Los directores Dr. Free Espinosa Torre, profesor titular del Departamento de Zoología de la Universidad de Sevilla, Dr. José Manuel Guerra García, Catedrático del Departamento de Zoología de la Universidad de Sevilla, y Dr. Carlos Navarro Barranco, Contratado Juan de la Cierva Incorporación del Departamento de Zoología de la Universidad de Sevilla, INFORMAN: Que esta Memoria de Investigación, titulada “Evaluación del impacto de las estructuras de defensa costera sobre la biota marina. Efectos a nivel local, regional y trófico”, fue realizada por Francisco Sedano Vera bajo su dirección, en el Departamento de Zoología de la Universidad de Sevilla. Considerando que reúne las condiciones necesarias para constituir un trabajo de Tesis Doctoral, autorizan su defensa ante los miembros del Tribunal para optar al título de Doctor con Mención Internacional. Sevilla, septiembre de 2020 El Director (1) El Director (2) El Director (3) Fdo. Free Espinosa Torre José Manuel Guerra García Carlos Navarro Barranco Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b VI Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b VII La presente Tesis Doctoral ha sido financiada por una beca de Formación de Personal Investigador (FPU – 15/00845) del Ministerio de Educación Cultura y Deporte de España, otorgada al doctorando desde el 19/10/2016 al 18/10/2020. Así mismo, parte de la experimentación ha sido financiada por el Ministerio de Economía y Competitividad (Proyecto CGL2017-82739-P cofinanciado por la Agencia Estatal de Investigación -AEIy Fondo Europeo de Desarrollo Regional -FEDER-) y el IV Plan Propio de Investigación de la Universidad de Sevilla. Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b XIV Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 15 Intr. gral. Introducción general En los últimos años hemos visto un gran auge en el sector urbanístico a nivel mundial. En poco más de cien años, la velocidad de urbanización se ha cuadruplicado y desde el año 1950 la población mundial ha crecido más de un 50 % (Fig. 1). Aunque a una velocidad menor en comparación con el periodo anterior (1950 – actualidad), en los años venideros la tendencia sigue al alza, estimándose una subida desde los 7.7 mil millones actuales hasta 9.7 mil millones en 2050 (UN DESA, 2019). Alrededor del 60% de la población se concentra en zonas costeras (Perkol-Finkel et al., 2018) y se espera que las tasas de crecimiento en esta zona sigan aumentando hasta el año 2050 (Merkens et al., 2016). Esto es debido a que la costa favorece ciertas actividades como el transporte, la explotación de recursos, el desarrollo de industrias o actividades turísticas. El escenario es muy similar en España, la cual también ha experimentado un gran crecimiento poblacional desde 1950 (Fig. 2). Esto ha provocado un gran aumento en la urbanización costera, incluyendo la introducción de numerosas estructuras para la defensa de la costa ante la subida del nivel del mar o eventos climáticos extremos entre otros. Dichas construcciones pueden provocar grandes alteraciones en la costa natural e incluso su destrucción, considerándose una de las principales causas de la pérdida de hábitats poco profundos (Airoldi y Beck Fig. 1. Crecimiento poblacional observado y estimaciones para el año 2100. Billion: mil millones. Fuente: United Nation, DESA. Population Division. World Population Prospects 2019. https://population.un.org/wpp Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 16 2007; Bulleri and Chapman, 2010). Ello conlleva una pérdida de servicios ecosistémicos, que se acentúa con la sobreexplotación de recursos costeros (Agardy y Alder, 2005), cuya demanda aumenta con el mencionado incremento en la población costera (Fig. 3). Los beneficios para el bienestar humano derivados de los servicios ecosistémicos son a menudo menos tangibles que otros intereses económicos más inmediatos (Kansky y Knight, 2014), realzando un conflicto de intereses que pone de manifiesto la importancia de enfocar decisiones medioambientales desde un punto de vista multidisciplinar. Tradicionalmente, en el diseño de estructuras artificiales se contemplan principal o únicamente aspectos físicos como la durabilidad o la disipación del oleaje. El material de construcción más utilizado es el hormigón, y su utilización está tan extendida que en el mundo de la construcción se le denomina al siglo XXI ‘el siglo del hormigón en los océanos’ (Mehta, 1991). El cemento Portland Fig. 2. Crecimiento poblacional observado y estimaciones para el año 2100 en España. Fuente: United Nation, DESA. Population Division. World Population Prospects 2019. https://population.un.org/wpp Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 17 Intr. gral. (principal adhesivo del hormigón) provoca alcalinidades entorno a pH 13 en la superficie de las estructuras de hormigón (Becker et al., 2020) y presenta componentes que son tóxicos para la vida marina (Lukens y Selber, 2004). Además, las estructuras artificiales de hormigón suelen tener superficies lisas y muy inclinadas (franja intermareal reducida) (Loke y Todd, 2016; Moreira et al., 2006). Todo ello provoca que las comunidades que se asientan en este tipo de estructuras sean diferentes (comunidades artificiales) y menos biodiversas en comparación con las asentadas en la roca natural cercana (Bulleri y Chapman 2010; Firth et al., 2016). Debido a ello, con el objetivo de reducir estas diferencias entre las comunidades artificiales y naturales, surge recientemente el campo de la ingeniería ecológica. En este campo, ingenieros, ecólogos Fig. 3. Representación del aumento poblacional en zonas costeras. Modificado de Barragán et al. (2015). Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 18 y stakeholders buscan una acción coordinada que promueva el desarrollo urbanístico satisfaciendo ciertos requerimientos medioambientales (Mamo et al., 2018), beneficiando de este modo tanto a la sociedad como al medioambiente. A medida que se intensifica la urbanización costera, aumenta la presión sobre las constructoras para que incorporen diseños ecológicos (ej. microhábitats, nuevos materiales). Sin embargo, la mayoría de las acciones de ecoingeniería se han llevado a cabo como proyectos piloto, hay pocas directrices para un uso práctico a nivel de usuario (O’Shaughnessy et al., 2019) y hay pocas evidencias de que los diseños desarrollados tengan aplicaciones a nivel global, ya que se desconoce si se obtendrán los mismos resultados bajo condiciones ambientales diferentes. En definitiva, se necesitan más evidencias antes de que los diseños de ecoingeniería se usen con asiduidad (Evans et al., 2019). En este contexto desarrollamos la presente tesis con el objetivo general de incrementar el conocimiento sobre los impactos provocados por estructuras de defensa costeras en las comunidades marinas poco profundas del Mar Mediterráneo, con un enfoque particular en el Mar de Alborán y la Bahía de Algeciras. Los datos aquí presentados ayudarán a entender y predecir mejor los efectos de la construcción de estructuras de defensa costera y, por lo tanto, contribuirán al desarrollo de medidas de ecoingeniería destinadas a mitigar dichos impactos. De la larga serie de impactos que produce la construcción de defensas costeras (Fig. 4), detallamos en los distintos capítulos de esta tesis la pérdida de biodiversidad a nivel local y regional, la pérdida de flora autóctona, los cambios a nivel trófico y los efectos cascada que afectan a niveles de organización superiores. Hemos dividido el trabajo en tres grandes capítulos, cada uno de ellos albergando dos publicaciones específicas y cuyos objetivos e hipótesis presentamos a continuación: 1. Capítulo 1: Debido a que la literatura actual raramente incluye la fauna asociada en las comparaciones entre estructuras artificiales y el sustrato natural, nuestro objetivo fue caracterizar dichas comunidades tanto a nivel de especie (usando los anfípodos como modelo) como a nivel de grandes grupos (usando la comunidad asociada al completo), así como identificar los principales factores que las estructuran. Además, enfocamos su estudio a nivel local para evitar el ruido que puedan crear distintas condiciones ambientales y gradientes geográficos. Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 19 Intr. gral. 1.1. En la primera publicación hemos caracterizado cuatro tipos de estructuras artificiales con el objetivo de identificar cuál alberga una comunidad más similar a la de los sustratos rocosos naturales adyacentes. Dicha caracterización incluyó la descripción abiótica de las estructuras y biótica de la comunidad sésil y vágil (macroy meiofauna) a nivel de grandes grupos con la finalidad de identificar posibles efectos cascada entre distintos niveles de la comunidad. Nuestras hipótesis fueron: 1. Debido a la distinta naturaleza abiótica, la diversidad y estructura de la comunidad de las distintas estructuras artificiales diferirán entre sí y en comparación con el sustrato natural adyacente. Además, las estructuras hormigonadas (acrópodos, cubos y dique vertical) se diferenciarán en mayor medida en comparación con la escollera (estructura artificial de roca natural). Consideramos que la composición y la complejidad estructural afectarán en mayor medida a la comunidad sésil. Fig. 4. Modificaciones en el hábitat (cajas naranjas) producidas por las tres fases de ingeniería (Construcción, Mantenimiento y Desmantelamiento). Se incluyen ejemplos de impactos provocados (cajas azules) a nivel local y regional (cajas cian). Fuente: Dafforn et al. (2015). Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 20 2. Teniendo en cuenta que un aumento de la complejidad estructural a nivel intermareal se relaciona con un aumento de la diversidad, hipotetizamos que las estructuras con mayor microrugosidad tendrán mayor número de taxones que las más lisas. 1.2. El objetivo de la segunda publicación fue confirmar que los patrones observados a nivel de grandes grupos en el capítulo anterior se mantienen a nivel de especie utilizando los anfípodos como modelo, poniendo al mismo tiempo en valor la utilidad de este grupo en el establecimiento de diferencias ecológicas entre tipos de estructuras. Hipotetizamos que la comunidad de anfípodos diferirá entre estructuras y en comparación con el sustrato natural adyacente. Dichas diferencias vendrán determinadas por la naturaleza abiótica del sustrato primario (la estructura artificial en sí), así como por la del sustrato secundario (la comunidad sésil). 2. Capítulo 2: Uno de los mayores desafíos de la ingeniería ecológica se encuentra en el establecimiento de diseños o medidas que sean aplicables a nivel global o regional. Es por ello que en el segundo capítulo nos enfocamos en estudiar los impactos de las estructuras artificiales de defensa costera a nivel regional con el objetivo de establecer si su ‘comportamiento’ es predecible a lo largo de una escala geográfica amplia. Para ello, hemos estudiado dos regiones del Mar Mediterráneo, el Mar de Alborán y la Isla de Creta (Grecia). 2.1. En la primera publicación (enviada a la revista) del segundo capítulo hemos caracterizado la biota intermareal del Mar de Alborán con el objetivo de identificar si la pérdida de biodiversidad asociada a distintas estructuras artificiales se conserva a lo largo de un gradiente geográfico. Nuestras hipótesis fueron: 1. La riqueza intermareal será menor en las estructuras artificiales que en los sustratos naturales más cercanos y este patrón se observará a lo largo del Mar de Alborán independientemente del tipo de estructura. 2. La estructura taxonómica diferirá entre estructuras artificiales y en comparación con el sustrato natural más cercano, siendo los diques verticales los de menor valor ecológico. Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 21 Intr. gral. 3. Esperamos que los patrones se vean influenciados por la escala espacial del estudio. 2.2. En la segunda publicación hemos caracterizado la biota submareal poco profunda asociada a escolleras a lo largo de la Isla de Creta (Grecia) con la finalidad de profundizar en el conocimiento de esta estructura, ya que tanto nuestros datos como los de otros investigadores coinciden en que este tipo de estructura artificial ofrece mayor valor ecológico que otras estructuras de hormigón (ej. diques verticales). En concreto, nuestro objetivo fue la caracterización de la biota bentónica desde un punto de vista taxonómico y funcional (refiriéndonos a su complejidad tridimensional). Nuestras hipótesis fueron: 1. La estructura de la comunidad y la diversidad diferirá entre las escolleras y el sustrato natural cercano independientemente de la localidad u orientación (Norte/Sur) a lo largo de la isla. 2. Los sustratos naturales tendrán una comunidad más desarrollada desde el punto de vista estructural, albergando mayor cantidad de algas con porte ramificado. 3. Capítulo 3: Poco se conoce sobre el impacto que tienen las estructuras artificiales en la estructura trófica de una comunidad o el nicho trófico de un individuo. Es por ello que en este capítulo hemos estudiado la estructura trófica (usando los anfípodos como modelo) y el nicho trófico (usando la lapa Patella caerulea) con el objetivo de evaluar si las estructuras artificiales afectan a los mismos. 3.1. En la primera publicación del tercer capítulo hemos caracterizado la estructura trófica y taxonómica de la comunidad de anfípodos asociada al alga Ellisolandia elongata en distintas estructuras artificiales a lo largo del Mar de Alborán con el objetivo de evaluar los efectos de éstas sobre la estructura trófica, la abundancia y composición de especies a lo largo de un gradiente geográfico amplio. Nuestras hipótesis fueron: 1. Las estructuras artificiales serán menos diversas y tendrán menores abundancias en comparación con los sustratos naturales adyacentes y por lo tanto tendrán una comunidad estructurada de forma diferente. 2. Las escolleras (estructura artificial de roca natural) serán más similares a los sustratos naturales en comparación con el resto de estructuras artificiales de hormigón. Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 22 3. La estructura trófica (porcentaje de carnívoros, herbívoros, detritívoros y omnívoros) diferirá entre las estructuras artificiales y los sustratos naturales adyacentes. 3.2. En la segunda publicación del tercer capítulo hemos estudiado el nicho trófico (usando el ratio isotópico δ13C y δ15N) de la lapa Patella caerulea en distintas estructuras artificiales a lo largo del Mar de Alborán con el objetivo de identificar posibles cambios en la dieta de esta lapa y por lo tanto evaluar su consideración en la futura gestión de estos animales. De acuerdo con estudios previos, hipotetizamos que las lapas explotarán un nicho trófico diferente en función del tipo de sustrato (artificial vs natural) y de los factores ambientales de la localidad. Referencias Agardy, T., Alder, J., 2005. Coastal Systems. In: Ecosystems and Human Well-being: Current Status and Trends, pp. 513-550. Airoldi, L., Beck, M.W., 2007. Loss, status and trends for coastal marine habitats of Europe. Oceanogr. Mar. Biol. Ann. Rev., 45, 345-405. https://doi.org/10.1201/9781420050943.ch7 Barragán, J.M., de Andrés, M., 2015. Analysis and trends of the world's coastal cities and agglomerations. Ocean Coast. Manag., 114, 11-20. https://doi.org/10.1016/j.ocecoaman.2015.06.004 Becker, L. R., Ehrenberg, A., Feldrappe, V., Kröncke, I., Bischof, K., 2020. The role of artificial material for benthic communities–Establishing different concrete materials as hard bottom environments. Mar. Environ. Res., 161, 105081. https://doi.org/10.1016/j.marenvres.2020.105081 Bulleri, F., Chapman, M.G., 2010. The introduction of coastal infrastructure as a driver of change in marine environments. J. Appl. Ecol., 47, 26–35. https://doi.org/10.1111/j.1365-2664.2009.01751.x Dafforn, K.A., Glasby, T.M., Airoldi, L., Rivero, N.K., Mayer-Pinto, M., Johnston, E.L., 2015. Marine urbanization: an ecological framework for designing multifunctional artificial structures. Front. Ecol. Environ., 13(2), 82-90. https://doi.org/10.1890/140050 Desa, U. N., 2019. World population prospects 2019: Highlights. United Nations Department for Economic and Social Affairs, New York (US). 46 pp. Evans, A.J., Firth, L.B., Hawkins, S.J., Hall, A.E., Ironside, J.E., Thompson, R.C., Moore, P.J., 2019. From ocean sprawl to blue-green infrastructure - A UK perspective on an issue of global significance. Environ. Sci. Pol. 91, 60–69. https://doi.org/10.1016/j.envsci.2018.09.008 Firth, L.B., Knights, A.M., Bridger, D., Evans, A., Mieskowska, N. et al., 2016. Ocean sprawl: challenges and opportunities for biodiversity management in a changing world. Oceanogr. Mar. Biol. Ann. Rev., 54, 193-269. https://doi.org/10.1201/9781315368597-9 Kansky, R., Knight, A.T., 2014. Key factors driving attitudes towards large mammals in conflict with humans. Biol. Conserv. 179, 93–105. https://doi.org/10.1016/j.biocon.2014.09.008 Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 23 Intr. gral. Lukens, R. R., Selberg, C., 2004. Guidelines for marine artificial reef materials. Second edition. Atlantic and Gulf States Marine Fisheries Commissions, Ocean Springs (US). 198 pp. Loke, L.H.L., Todd, P.A., 2016. Structural Complexity and component type increase intertidal biodiversity independently of area. Ecology 97, 383–393. https://doi.org/10.1890/15-0257.1 Mamo, L.T., Kelaher, B.P., Coleman, M.A., Dwyer, P.G., 2018. Protecting threatened species from coastal infrastructure upgrades: The importance of evidence-based conservation. Ocean Coast. Manag., 165, 161-166. https://doi.org/10.1016/j.ocecoaman.2018.08.028 Mehta, P. K., 1991. Concrete in the marine environment. Elsevier Applied Science, New York (US). 214 pp. Merkens, J.L., Reimann, L., Hinkel,J., Vafeidis, A.T., 2016. Gridded population projections for the coastal zone under the Shared Socioeconomic Pathways. Global Planet. Change, 145, 57-66. https://doi.org/10.1016/j.gloplacha.2016.08.009 Millennium Ecosystem Assessment, 2005. Ecosystems and Human Well-being: Synthesis. Island Press, Washington, DC. Moreira, J., Chapman, M.G., Underwood, A.J., 2006. Seawalls do not sustain viable populations of limpets. Mar. Ecol. Prog. Ser. 322, 179–188. http://dx.doi.org/10.3354/meps322179 O’Shaughnessy, K.A., Hawkins, S.J., Evans, A.J., Hanley, M.E., Lunt, P., Thompson, R.C., Francis, R.A., Hoggart, S.P.G., Moore, P.J., Iglesias, G., Simmonds, D., Ducker, J., Firth, L.B., 2020. Design catalogue for eco-engineering of coastal artificial structures: a multifunctional approach for stakeholders and endusers. Urban Ecosyst, 23(2), 431-443. https://doi.org/10.1007/s11252-019-00924-z Perkol-Finkel, S., Hadary, T., Rella, A., Shirazi, R., Sella, I., 2018. Seascape architecture–incorporating ecological considerations in design of coastal and marine infrastructure. Ecol. Eng., 120, 645-654. https://doi.org/10.1016/j.ecoleng.2017.06.051 Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Local effects of coastal infrastructure 30 2018), they can harbour epibenthic communities more similar to natural ones (Gacia et al., 2007; Pister, 2009). This study aimed to identify which artificial structures are better surrogates of hard natural habitats comparing three different community levels (i.e. sessile taxa and vagile macroand meiofauna). The main drivers of differences among structures were identified and discussed, arising relevant information for the field of ecological engineering. More specifically, we hypothesized that: 1. Given the fact that different hard substrates lead to different communities (Bulleri and Chapman, 2010; Perkins et al., 2015) and that materials of construction (Ido and Shimrit, 2015) and complexity (Coombes et al., 2015; Sempere-Valverde et al., 2018) play important roles in their development, we hypothesized that community structure and diversity measures would differ among substrates. Also, concrete-based structures (seawall, cube and acropod) would be more similar among them than in comparison with natural rockbased substrates (rip-rap and natural rock). Furthermore, both composition and complexity would drive those differences more strongly over the sessile compartment. 2. Taking into account that higher microscale roughness and the addition of complexity is related to increasing taxa richness in the intertidal environment (Evans et al., 2016; Firth et al., 2014a), we hypothesized that structures with higher microscale roughness would have higher number of taxa at the three community levels studied. Furthermore, we approached the study of macroand meiofauna levels using mixed coarse taxonomic resolution (Chapman et al., 2005) to support this procedure when facing taxonomically challenging groups in the assessment of artificial structures. The results will be of interest for management authorities that pursue the inclusion of simple but reliable procedures into monitoring programs. Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 31 Chapter 1 Materials and methods Study area and environmental data Algeciras Bay is located in the North coast of the Strait of Gibraltar. This Strait is a marine biodiversity hotspot with highly diverse and well-structured marine communities (GarcíaGómez et al., 2003) due to the confluence of two biogeographical realms (Mediterranean and North Atlantic) (Costello et al., 2017). Its biodiversity and ecology have been the focus of numerous studies in the last decades (Guerra-García et al., 2009). Algeciras Bay is an important industrial area, with chemical factories, refineries, thermal power plants, iron works, paper mills and shipyards, along with a major port (Conradi et al., 1997), which makes this bay a suitable area for studying the effects of anthropogenic disturbances. Algeciras Harbour is in the West side of the Bay (Fig. 1). Its shipping activities have increased since its construction, surpassing in 2017 100 mT of freight, becoming the fifth biggest harbour in Europe (www.ec.europa.eu/eurostat/). Our study area comprises four different coastal defence structures (seawall, cubes, acropods and rip-raps) that surround the harbour, and the nearest natural rocky shore as control habitat. All substrates (artificial and natural) are located within approximately 1 km. According to previous studies, all the habitats sampled showed similar annual averages of dissolved organic matter, silting, hydrodynamics, suspended solids and temperature (Carballo et al., 1996). This allowed us to explore substrate influence on biotic communities avoiding other confounding environmental effects. Biotic analyses In January 2017, each substrate (four artificial and the natural control, Fig. 1) was sampled allocating three random sites within it. At each site, three 20 × 20 cm quadrats were scraped and preserved in 96% alcohol until laboratory analyses. Therefore, the experimental design used in the statistical analyses had two factors: ‘Habitat’ (Ha), a fixed factor with five levels (Natural, Rip-rap, Acropod, Cube and Seawall) and ‘Site’ (St), a random factor with three levels (Site 1, Site 2, Site 3) nested in Ha. Samples were taken over vertical surfaces of each Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Local effects of coastal infrastructure 32 substrate during low tide at low intertidal zone (5–30 cm over the lowest tidal level). In the laboratory, all sessile fauna and flora were volumetrically quantified and identified to the lowest possible taxonomic resolution. Some taxa (Spirobranchus sp./Dendropoma sp. and Gelidium sp./Caulacanthus sp.) were quantified together and referred to as Spirobranchus sp./Dendropoma sp. reef and Gelidium sp./Caulacanthus sp. turf in the results, given the difficulty of measuring them individually. Each sample was sieved through a 0.5 mm mesh in order to obtain associated macrofauna and through a 34 μm mesh in order to retain meiofauna. Macroand meiofauna were sorted into “High-Taxonomic Groups” (HTGs) (Timms et al., 2013). This “low” taxonomic resolution has been frequently used to assess differences in the structure of benthic communities (see Otero-Ferrer et al., 2019). Since meiofaunal abundances were much over > 2000 individuals per sample, samples were resuspended with a circular movement in a known volume and subsamples of 3 ml were taken for analysis (Danovaro et al., 2003). Abundances of each identified taxon were counted and, based on these data, the number of taxa (S) and Shannon-Wiener diversity (H′) were calculated. To test for differences in S and H′ between substrates, we applied two-way ANOVA when there was homogeneity of variances (i.e. for sessile community) and generalized linear mixed models (GLMMs) when there was heteroscedasticity. For every analysis the same above-mentioned design was used. Homogeneity of variances was confirmed using Cochran's test. When ANOVA detected significant differences for a given factor, the source of difference was identified by applying the Student–Newman–Keuls (SNK) test. For the associated communities Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 33 Chapter 1 (macroand meiofauna), univariate tests were performed using GLMMs including the effect of scraping volume (covariate) in the models. A number of taxa (counts) were fitted to Poisson distribution while Gaussian distribution was used for Shannon's diversity. The absence of overdispersion of residuals was confirmed with Shapiro-Wilk tests. When no variance was detected among sites, random effects (‘Site’ factor) were not included in the model and the significance level was lowered to p < 0.01 to reduce Type I error. Two-way ANOVAs were carried out with GMAV5 software (Underwood et al., 2002), while GLMMs were conducted with Rstudio v.1.2.5001. PERMANOVA was run to evaluate differences in community structure based on a BrayCurtis similarity matrix derived from square root transformed data. Non-metric multidimensional scaling (nMDS) was used to visualize patterns in community structure between substrates. To account for the variance in vagile taxa abundances and composition dependent on the volume of sessile scrapes, the total volume of each scrape was used as covariate in the statistical analyses. Bray-Curtis dissimilarity between substrates (natural vs each of the artificial ones) was also calculated with SIMPER (SIMilarity PERcentages) using standardized (by scraped volume) abundance data (except for sessile community) and square root transformation. Analyses were carried out using PRIMER v.6 + PERMANOVA package (Clarke and Gorley, 2006). Abiotic analysis Lithologic nature of each substrate was also characterized. Three chips from each substrate were powdered in the laboratory using a ball mill with stainless steel balls as grinding media. The elemental composition and calcination percentage of each sample was quantified by Xray fluorescence (XRF) using an AXIOS spectrometer. Mineralogic absorption spectra were Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Local effects of coastal infrastructure 34 detected by X-ray diffraction (XRD) using a powder diffractometer (Bruker D8 Advance) equipped with a high temperature chamber (Anton Paar XRK 900) and a fast response/high sensitivity detector (Bruker Vantec 1) with radial Soller slits (full methodology can be accessed in Valverde et al., 2015). Afterwards, XRF and XRD data were interpreted to quantify the crystallinity and lithology composition of each sample using DRIFAC.EVA.4.1 program. Differences in mineralogic content between substrates were graphically represented using nMDS based on a Euclidean Distance similarity matrix of untransformed data. Additionally, wave exposure was quantified at each habitat based on a fetch model index developed by Howes et al. (1994). Fetch models have been successfully used to predict marine community patterns (e.g. Ros et al., 2016) by providing quantitative estimates of wave exposure using a combination of two indices: maximum fetch and modified effective fetch. Maximum fetch is defined as the maximum fetch distance in km measured from the point of interest. When a vector does not find and obstacle (i.e. open ocean occurs), a value of 1000 km is conventionally used. Effective fetch (Fe) is calculated from the equation: Fe = [Σ(cos Өi) × Fi] / Σcos Өi, where Өi is the angle between the shore-normal and the directions 0°, 45° to the left and 45° to the right, and Fi is the fetch distance in km along the relevant vector. Combining the values obtained for each index, wave exposure class of each habitat was determined based on the classification proposed by Howes et al. (1994). We carried out a constrained ordination approach to assess how well the biological data relate to different abiotic variables that characterize the different substrates. We considered calcination percentage (carbonates content), roughness (macroand microscale), crystallinity, age and elemental composition (only elements with a relevant concentration over 3%: silicon, calcium and magnesium; full composition in Supplementary Table 1). Age of the different artificial structures was quantified based on the date of construction. Since it is difficult to infer the age of natural substrates, for analytic purposes, we chose the oldest possible date in the same order of magnitude than the oldest artificial structure. Macroscale roughness was calculated over 15 m length transects. Three transects were selected at each substrate and a flexible meter was laid directly over it, trying to conform as closely as possible to all contours Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 35 Chapter 1 of the bare substrate. Regarding microscale roughness, three 15 cm profile gauges with 0.5 mm pins were pushed onto the bare rock to record the surface of each substrate (Frost et al., 2005). The resulting profiles were photographed, and the images were digitally processed with Adobec Photoshop to obtain two coloured images (Fig. 2A). The length of the contour of the profile was obtained with ImageJ software. In both cases (macroand microscale), substrate roughness was calculated as in Rivera-Ingraham et al. (2011a, 2011b) using the equation by Blanchard and Bourget (1999): Roughness = Tr / Ts, where Tr is the contour measured between two points and Ts the linear distance between those points. A Principal Component Analysis (PCA) ordination, performed on normalized data, was used to display the relationship between substrates according to elemental composition, calcination percentage, macroand microscale roughness, crystallinity and age. To explore relationships between abiotic and biotic (sessile, associated vagile macrofauna and meiofauna) data, we used distance-based Redundancy Analyses (dbRDA). dbRDA was chosen over Canonical Correspondence Analyses (CCA) since data fitted a linear species response. Linearity was deducted as in Ter Braak and Smilauer (1998) according to the first axis length in Detrended Correspondence Analysis (DCA) (< 3, linear;>4, unimodal). Prior to analyses, multicollinearity between abiotic factors was tested using Draftsman plots based on Spearman correlation. Only one abiotic factor was used in the analyses when there were high pairs of correlation. If the constrained ordination still portrayed collinearity between abiotic factors, the variable most affected was eliminated attending to Variance Inflation Factor (VIF) in order to avoid misinterpretation of data due to unstable canonical coefficients (Ter Braak, 1988). Collinearity was neglected when VIF < 10 according to Dormann et al. (2013). dbRDA was run using square root transformed biological matrix paired with standardized abiotic matrix. In addition, significance levels (p < 0.05) were calculated under 1000 random permutations. The relationship between biotic data and abiotic variables were portrayed using dbRDA biplots. DCA and dbRDA analyses were carried out Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Local effects of coastal infrastructure 36 using RStudioc Version 1.1.453. PCA and Draftsman Plot were carried out using PRIMER v.6 + PERMANOVA package (Clarke and Gorley, 2006). Results Characterization of each structure To characterize the various substrates sampled, different abiotic measurements were taken into account (Table 1). Although wave exposure (measured as Fetch index) slightly differed between substrates, all substrates were qualitatively classified as semiexposed (after Howes et Fig. 2. A: Sample images of profiles measured at the five different substrates to obtain microscale roughness using the formula: Roughness = Tr / Ts, where Tr is the total length of the contour and Ts is the linear distance between two points. B: Histograms for average macroand microscale roughness. Bars represent standard deviations. Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 37 Chapter 1 al., 1994) (see Table 1). Elemental and mineralogical composition clearly varied among substrates (Fig. 3). Biotic analyses: how do different community levels vary between substrates? The sessile community comprised 15 taxa (Mytilus galloprovincialis, Spirobranchus sp./Dendropoma sp. reef, Calpensia sp., Perforatus perforatus, Pyura dura, Ulva sp., Rugulopteryx okamurae, Ceramium sp., Ellisolandia elongata, Gelidium sp./Caulacanthus sp. turf, Jania rubens, Laurencia sp. and Lithophyllum incrustans). Presence and dominance of each taxa differed clearly according to the substrate type (Fig. 4). Natural substrates were characterized by a dominance of the calcareous turf alga E. elongata and the scarcity of gregarious species such as P. perforatus and M. galloprovincialis. Seawalls presented the opposite pattern with a dominance of P. perforatus and M. galloprovincialis while E. elongata was absent. Fig. 3. Up: X-ray diffractograms obtained for one replicate of each substrate. Down: Two dimensional nMDS portraying the differences in mineralogical content between replicates of each substrate (full data in Supplementary Table 2). The three replicates of natural substrate are superimposed due to its homogeneous composition. Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Local effects of coastal infrastructure 38 1 Table 1: Location and descriptors of five different substrates sampled. Macro: macroscale roughness; Micro: microscale roughness; n.a.: not applicable. Natural Rip-rap Cube Acropod Seawall Latitude 36°06'34.1"N 36°07'01.2"N 36°07'12.1"N 36°07'03.2"N 36°07'00.5"N Longitude 5°25'55.4"W 5°26'07.9"W 5°26'07.6"W 5°26'07.4"W 5°25'02.4"W Date of deployment n.a. 1997 1955 1997 2008 Distance from natural rock n.a. 0.90 km 1.19 km 0.96 km 1.50 km Effective fetch (km) 95.79 116.52 74.66 116.52 43.15 Wave exposure class Semi-exposed Semi-exposed Semi-exposed Semi-exposed Semi-exposed Mayor component Quartz Calcite Quartz-Calcite Dolomite Magnesium calcite Macro (average ± SD) 1.05 ± 0.03 1.26 ± 0.09 1.43 ± 0.06 1.47 ± 0.24 1.00 ± 0.01 Micro (average ± SD) 1.62 ± 0.22 1.30 ± 0.04 1.62 ± 0.31 1.20 ± 0.07 1.00 ± 0.01 Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 39 Chapter 1 The sessile community of rip-raps was also dominated by E. elongata while cubes had abundant P. perforatus with patches of E. elongata and M. galloprovincialis. Acropods held the most heterogenous sessile community, characterized by abundant patches of P. perforatus, E. elongata and Spirobranchus sp./Dendropoma sp. reef depending on the site (although differences were not statistically significant between sites; data not shown). As in the nMDS plot (Fig. 4), SIMPER analyses (Table 2) showed that rip-raps supported the least dissimilar sessile communities compared with natural substrates, while seawalls were the most dissimilar. PERMANOVA further confirmed differences in community structure composition, showing significant differences among substrates but not within sites of each substrate (see pair-wise tests in Table 3). In addition, sessile communities on natural substrates were richer compared with each of the artificial substrates. In contrast, due to the high dominance of E. elongata (Table 2, Supplementary Table 3), natural and artificial substrates had similar Shannon's diversity values (Fig. 5, Supplementary Table 4). Regarding associated macrofauna, 16 major taxonomic groups were identified (Cnidaria, Platyhelminthes, Nemertea, Sipuncula, Bivalvia, Gastropoda, Polyplacophora, Annelida, nonCaprellidae Amphipoda, Caprellidae, Decapoda, Isopoda, Tanaidacea, Echinoidea, Pycnogonida and Insecta). Except Caprellidae, Insecta and Polyplacophora (absent from seawalls) and Nemertea (absent from rip-raps), all macrofaunal groups were present in the different substrates. In fact, number of taxa in natural substrates was only marginally higher compare with cubes (Fig. 5, Supplementary Table 4). However, clear differences in taxa abundances were recorded (Fig. 4, Supplementary Table 1). This translated into significant differences in Shannon diversity values, being significantly higher in cubes, acropods and ripraps. Even with the addition of the covariate (that was highly significant), there were significant differences in communities between natural substrates and acropods, cubes and seawalls, but not with rip-raps (see PERMANOVA in Table 3). Natural substrates were dominated by noncaprellid amphipods together with other peracarids such as isopods, tanaids and caprellids. Gastropods and annelids (mainly polychaetes) were also quite abundant compared with the rest of taxa. Seawalls were dominated by non-caprellid amphipods, isopods and annelids Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Local effects of coastal infrastructure 46 Regarding the meiofauna, the model of abiotic variables accounted significantly (p < 0.01) for 74.5% of the total inertia, although only the marginal effects of microscale roughness and age were significantly correlated. Cubes, acropods and rip-raps separated along axis 1 for their higher microscale roughness, whereas seawalls and natural substrates did along axis 2 for their younger and older age respectively. Fig. 7. Distance-based Redundancy Analyses (dbRDA) plots of correlations between the different community levels and the selected abiotic variables (represented by arrows). A: sessile community; B: associated macrofauna; C: associated meiofauna; black symbols: artificial substrates; white symbols: natural substrate. Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 47 Chapter 1 Table 3: PERMANOVA results for sessile, associated macroand meiofauna communities (based on taxa composition and abundances). Pair-wise tests only consider comparisons between natural substrates and each artificial substrate. Ha: Habitat [five levels: N(natural), R(rip-rap), A(acropod), C(cube) and S(seawall)]; Si(Ha): Site; CO: covariate (volume of secondary substrate); df: degrees of freedom; MS: mean square; p: level of significance; ***: p < 0.001; n.s.: not significant. Sessile community Source of variation df MS Pseudo-F Perms. p Ha 4 19032 33.676 9896 *** Si(Ha) 10 565.15 0.88467 9881 n.s. Residual 30 638.83 Total 44 Pair-wise tests Levels of factor (Ha) N≠(R,A,C,S) Associated macrofauna Source of variation df MS Pseudo-F Perms. p CO 1 10929 19.945 9949 *** Ha 4 3149.3 5.6499 9932 *** Si(Ha) 10 565.37 1.1018 9886 n.s. Residual 29 513.12 Total 44 Pair-wise tests Levels of factor (Ha) N=R, N≠(A,C,S) Associated meiofauna Source of variation df MS Pseudo-F Perms. p CO 1 7882.1 27.419 9941 *** Ha 4 3204.7 11.261 9917 *** Si(Ha) 10 282.16 0.94659 9857 n.s. Residual 29 298.08 Total 44 Pair-wise tests Levels of factor (Ha) N≠(R,A,C,S) 1 Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Local effects of coastal infrastructure 48 1 Table 4: Permutation test for dbRDA under reduced model for all constrained eigenvalues and the marginal effects of each abiotic variable tested at the three different community levels. Proportion of inertia explained by the model is provided. df: degrees of freedom; sqs: squares; p: level of significance; *: p < 0.05; **: p < 0.01; ***: p < 0.001; n.s.: not significant. Sessile community df % Explained F P Constrained model 5 78.3% 6.498 *** Residual 9 df Sum of sqs. F p Macro 1 0.3745 5.6170 * Micro 1 0.3721 5.5809 ** Crystall. 1 0.1055 1.5829 n.s. Age 1 0.6359 9.5387 *** Calcium 1 0.2383 3.5743 * Residual 9 0.6000 Associated macrofauna df % Explained F P Constrained model 5 70.9% 4.3846 ** Residual 9 df Sum of sqs. F p Macro 1 0.1606 6.2060 ** Micro 1 0.0821 3.1722 * Crystall. 1 0.0337 1.3045 n.s. Age 1 0.1427 5.5124 ** Calcium 1 0.0322 1.2446 n.s. Residual 9 0.2329 Associated meiofauna df Explained F P Constrained model 5 74.5% 5.2685 ** Residual 9 df Sum of sqs. F p Macro 1 0.0512 2.3058 n.s. Micro 1 0.2547 11.481 *** Crystall. 1 0.0192 0.8670 n.s. Age 1 0.1482 6.6789 * Magnesium 1 0.0319 1.4389 n.s. Residual 9 0.1997 Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 49 Chapter 1 Discussion Previous studies on sessile and vagile invertebrate communities have shown the poor performance of artificial structures compared with hard natural habitats, regarding community structure and diversity (Bulleri and Chapman, 2004; Evans et al., 2016; Gacia et al., 2007; Moschella et al., 2005; Perkol-Finkel et al., 2006). The abiotic variables measured for each substrate in our study (such as composition, roughness or age) explained high proportions of variance for each community level, indicating their important role in structuring these communities. In fact, a broad range of abiotic factors have been identified as drivers of the ecological differences between natural and artificial substrates. For example, SempereValverde et al. (2018) found that community composition was related to the nature of the substrate. Mercader et al. (2017) highlighted that complex artificial reefs boosted the species richness within a harbour, and Chapman and Underwood (2011) reviewed the importance of inclination. The substrate age has been frequently addressed (Antoniadou et al., 2010; Coombes, 2011; Dong et al., 2016; Ferrario et al., 2016) for its obvious importance for colonizers. The different substrates of our study were located in the same area, exposed not only to similar moderate wave action but also to similar pollution levels. This allowed us to explore the influence of substrates on the biota regardless of the potential effects of environmental and geographical factors. Substrate complexity correlated significantly with the sessile biota, vagile macrofauna and meiofauna, although only at microscale for the latter. At the intertidal level, substrate heterogeneity (e.g. rock pools and crevices) can increase biodiversity by offering shelter against stressful environmental conditions (e.g. desiccation at low tide) (e.g. Evans et al., 2016; Firth et al., 2014b; Ostalé-Valriberas et al., 2018; Perkins et al., 2015). This usually favours natural habitats compared with the featureless surfaces of coastal defence structures. In addition, higher roughness at the scale of centimetres could improve larvae and spore recruitment (Koehl, 2007; Sempere-Valverde et al., 2018) and increase refuge availability against predators (Loke et al., 2017; Strain et al., 2018a). Despite this, it is known that some species (e.g. Balanus improvisus) Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Local effects of coastal infrastructure 50 have higher propensity for smooth surfaces (Berntsson et al., 2000), a common condition of concrete structures. Higher abundances of large limpets have been related to smooth surfaces or medium microscale roughness depending on the species (Rivera-Ingraham et al., 2011a; Rivera-Ingraham et al., 2011b), while higher complexity at larger scale could provide shelter for other megafauna grazers such as sea urchins (Dame, 2008) or even invasive crabs (Katsanevakis et al., 2010). According to Miller and Gerstner (2002), our measurements for cubes, rip-raps and natural substrates indicated a high complexity at centimetre scale. Interestingly, at macroscale level, cubes and rip-raps were more heterogeneous than natural substrates. Therefore, higher microscale roughness coupled with lower macroscale heterogeneity might be boosting the occurrence of more sessile taxa in natural substrates through recruitment and competition effects. Substrate material is another important factor affecting community composition on artificial substrates (Coombes et al., 2015; SempereValverde et al., 2018). Our results showed a clear differentiation of substrates according to mineralogic composition, although calcium (Ca) correlated significantly only with the sessile community. Calcium was present in the artificial substrates mainly as polymorphs of calcium carbonate (calcite, magnesium calcite, aragonite and dolomite) and was almost absent from natural substrates, which were principally composed of quartz (see Supplementary Table 3). Sea water reduces the pH, modifying concrete properties (Ponti et al., 2015) and potentially promoting the dissolution of carbonated minerals and increasing bicarbonate availability around the surface (Mos et al., 2019). Green et al. (2013) related higher percentages of burrowing bivalves to higher aragonite saturation. In fact, we detected the invasive mussel Myoforceps aristatus in concrete structures (data not shown). Furthermore, leaching components of cement are known to raise pH levels at the surface of concrete structures (Ido and Shimrit, 2015), fostering alkatolerant and endolithic taxa (Ponti et al., 2015). Our results showed higher biomass of M. galloprovincialis and P. perforatus in concrete-based substrates compared with rip-raps and natural substrates. This is also in accordance with Guilbeau et al. (2003), whose results demonstrated that high pH cements boosted the attachment of barnacles and with Anderson (1996), who showed that high alkalinity Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 51 Chapter 1 at the surface of concrete enhanced oyster settlement. Although mussels and barnacles were present on every concrete structure in this study, seawalls harboured the greater biomass. Even though wave exposure was moderate at every substrate, seawalls lacked porous structures and avoid the waves flowing through, dissipating wave energy less efficiently than boulder like structures (Jung et al., 2012). It is also possible that seawalls were exposed to stronger currents, as it was the only structure not connected to mainland. Therefore, it is probable that a combination of all the above-mentioned factors is boosting the development of filter feeding taxa on the seawall. Contrary to our results, Bavestrello et al. (2000) observed a fewer taxa in rocks with high quartz content and Gacia et al. (2007) did not find differences on the epibiota related to different mineral composition. Moreover, several authors have pointed out that other attributes, such as colour (Dobretsov et al., 2013; Finlay et al., 2008) or porosity (Berntsson et al., 2000), could influence ‘larval choice’ in settling on different substrates. Overall, our results support the idea that substrate roughness and composition play important roles in structuring intertidal sessile communities, although we were not able to disentangle this from other variables such as age, that was also significantly correlated. In fact, Nicoletti et al. (2007) distinguished M. galloprovincialis (that dominated the youngest structure in this study, i.e. seawalls) as a dominant species during the first years following an artificial reef deployment, although this appeared to be more related to sedimentation processes rather than the artificial structure itself. In addition, the cover of barnacle Amphibalanus amphitrite diminishes with age of biofilm (Faimali et al., 2004). On the contrary, Moschella et al. (2005) considered barnacles and mussels as later colonizers of low-crested coastal defence structures. Furthermore, some authors have estimated that it takes from 5 to 20 years for artificial structures to reach climax communities (Coombes, 2011; Hawkins et al., 1983; Pinn et al., 2005), while others suggested that communities on low crested structures never reach climax (Gacia et al., 2007). In some situations, benthic communities are known to change over years (Burt et al., 2011; Ponti et al., 2015) and it has also been proposed that incomplete succession could be a persistent stable state (Ferrario et al., 2016 and references therein). We are yet far from understanding if age plays a critical role or if its effect is overwritten by other factors Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Local effects of coastal infrastructure 52 acting at faster scales. Further experimentation using controlled parameters and longer experimental data (Firth et al., 2016) will be needed to fully assess the importance of age. According to the associated fauna, number of taxa did not differ substantially between natural and artificial substrates. However, due to the absence of highly dominant taxa (in terms of abundance) in cubes, acropods and rip-raps, Shannon's diversity was significantly higher in these structures. Furthermore, similarities increased among substrates compared with the sessile biota. This was probably an artefact of using “High-Taxonomic groups” (HTGs), but also due to the capability of barnacle patches, mussel beds and coralline turfs (the most abundant sessile taxa in our study) of harbouring abundant and diverse associated communities (e.g. Asnaghi et al., 2015; Chintiroglou et al., 2004; Kelaher et al., 2004). Substrate roughness and age were the main drivers affecting the vagile macrofauna. It is possible that substrate roughness affects the occurrence of vagile animals that crawl over the substrate, such as certain gastropods or polyplacophorans. In fact, the latter were absent from the least heterogeneous substrate (seawalls). This is in accordance with Moreira et al. (2007) who found higher abundances of chitons in crevices than on exposed surfaces on seawalls. Increasing shade and roughness on intertidal artificial structures has proven to be one of the most effective measures to improve biodiversity of mobile invertebrates (Strain et al., 2018b). Nonetheless, most of the identified taxa were small macroinvertebrates and meiofauna that need a secondary substrate (sessile) to cling to. The quality and amount of resources provided by sessile host species (such as food, habitat, predator or desiccation refuge) is highly dependent on both morphological and biological features of the secondary substrates (e.g. complexity, epiphytic load, presence of chemical defence or life cycle) (Olafsson, 2016). Since the community structure of the secondary substrate greatly affects the distribution of associated fauna (Kelaher, 2002; Olafsson, 2016; Symstad et al., 2000; Torres et al., 2015), the differences detected herein are thus expected to better respond to the patterns observed for the sessile community. In this sense, the associated communities of artificial structures with greater abundances of mussels and barnacles (the concrete ones) clearly differed from those with higher abundances of coralline algae (rip-rap and natural). Both M. galloprovincialis and E. elongata provided large volumes Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 53 Chapter 1 of secondary substrate but presumably with very different complexity. In line with our results, Palomo et al. (2007) found that isopods and amphipods were the most abundant taxa associated with mussels, and Yakovis et al. (2007) suggested that the cavity-loaded structures of barnacles shaped the associated macrofauna. Amphipods were also dominant at natural habitats but, in our study, abundance of isopods was clearly higher on substrates dominated by P. perforatus (seawalls), probably because the habitat they provide fits adults' size and gives refuge against predators and environmental stress. This supports the idea that facilitation processes could be species-specific (Bulleri et al., 2016) and that the vagile fauna can have preferences for some surfaces depending on the characteristics provided by the sessile biota (Moura et al., 2008). Therefore, the contrasting complexities of different sessile taxa probably determine several differences in the associated communities studied. However, biological features of the secondary substrates also contribute to those differences (Kelaher, 2002). The surface of mussel shells is an appropriate substrate for bacteria and microalgae (Tsuchiya and Nishihira, 2007) which in turn serve as food for mobile taxa (Palomo et al., 2007). It is known that different artificial structures harbour different biofilms (Tan et al., 2015) and that microbial communities associated with the same organism differ depending on the natural or artificial nature of the primary substrate (Marzinelli et al., 2018). Moreover, marine invertebrate larvae can respond to chemical cues produced by biofilms and their associated organisms. For example, encrusting red algae foster the settlement of certain species of gastropods, polychaetes and echinoderms while some bivalves are attracted to filamentous red algae (see Pawlik, 1992 for a review). Meiofauna is also expected to be influenced by structural complexity and biological interactions. Microhabitats created by biogenic structures are known to determine meiofaunal abundances (Muralikrishnamurty, 1983; Passarelli et al., 2012). Regarding meiofauna, mussel beds and barnacles can have similar functionality than algal turfs (Giere, 2009), which provide shelter from desiccation and predators (Ape et al., 2018; Muralikrishnamurty, 1983). However, our results showed that different sessile taxa favoured the attachment of abundant and rich meiofaunal communities but with significantly different community structure. Ape et al. (2018) also reported differences in intertidal meiofaunal communities associated to macroalgae and Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Local effects of coastal infrastructure 54 mussels. They are likely driven by architectural differences between mussels and algae. For example, some taxa (e.g. Peltidiidae and Porcellidiidae copepods) have a depressed body and specialized appendices to attach to the algal canopy (Gibbons, 1991; Giere, 2009). Atilla et al. (2003) also found higher abundances of phytal copepods in algal-covered substrates. In fact, in our study copepods belonging to the Porcellidiidae family were much more abundant in natural substrates, that were mainly covered by algal turfs (Sedano et al., unpublished data). Due to these adaptations, copepods and ostracods are abundant in phytal meiofaunal communities (Giere, 2009). Accordingly, the lowest abundance of ostracods was found on seawalls, where algae were very scarce. As already mentioned for the macrofauna, biological features may also play important roles in structuring meiofaunal communities. Passarelli et al. (2012) found more developed diatom biofilms on biogenic structures and Sempere-Valverde et al. (2018) related higher primary production and abundances of diatoms to increasing substratum roughness. Diatoms are a food resource for kinorhynchs (Herranz et al., 2014; Nebelsick, 1993 and references therein) and even the main one for shallow water forms (Giere, 2009). In our study, kinorhynchs were restricted to the highly heterogenous and siliceous natural substrates (except for one replicate of rip-raps), which could be related to a greater development of diatoms. In summary, the physical and biological features of the studied sessile community (secondary substrate) together with the nature of the primary substrate could be influencing their associated fauna, not only through species specific processes but also at larger scales. Conclusions Our results showed clear differences between substrates for the three community levels studied (sessile community, vagile macrofauna and meiofauna) and suggest that overall, ripraps are better surrogates of natural substrates in terms of community structure and taxa composition. Even so, rip-raps have been previously identified as poor surrogates of natural Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 55 Chapter 1 habitats in the Mediterranean see (Gacia et al., 2007; Moschella et al., 2005; Sedano et al., 2019) but see Liversage and Chapman (2018) for a review about benefits of incorporating boulder habitats. In general, we showed that artificial structures have lower taxa richness (for the three community levels) compared with the natural rock (although not always significantly). It is known that taxa richness in artificial structures can be increased by mitigating measures (Perkins et al., 2015), such as the creation of rockpools (Ostalé-Valriberas et al., 2018). Therefore, we hypothesized that structures with higher microscale roughness will have higher number of taxa in comparison with smoother ones. However, we found that cubes did not have significantly higher richness in comparison with the other substrates, despite their highest microscale roughness due to strong weathering through time. As already suggested by Perkins et al. (2015), this supports the idea that increasing structural complexity in concrete substrates is not enough to mitigate biodiversity loss. Thus, new ecoengineering actions should compromise between the use of sustainable materials and the addition of complexity. Although the spatial arrangement of the different structures may affect the obtained results, we showed that physical attributes (micro and macroscale roughness), composition (only for sessile) and age of the structures seem to play important roles in structuring the studied communities under similar environmental conditions. They especially affected the sessile community, initiating strong cascading effects that were detectable at high taxonomic level in the associated fauna. This reinforces the usefulness of both macrofaunal and meiofaunal communities to assess different artificial coastal defence structures in comparison with nearby natural substrates (Sedano et al., 2014). The patterns found by using a mixed coarse taxonomic resolution (Chapman et al., 2005) support the inclusion of fast but reliable procedures in management and monitoring plans (Chatzinikolaou and Arvanitidis, 2016), especially by harbour management authorities and ecoengineers that seek sustainable development goals. These results are of major importance, since the cascading effects can ultimately affect higher trophic levels such as fish (Cordell et al., 2017) and have economic consequences. Although some direct effects over associated fauna could be expected, the tight relationships of sessile taxa with their associated fauna probably masked those effects. Further Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Local effects of coastal infrastructure 62 Palomo, M.G., People, J., Chapman, M.G., Underwood, A.J., 2007. Separating the effects of physical and biological aspects of mussel beds on their associated assemblages. Mar. Ecol. Prog. Ser. 344, 131–142. https://doi.org/10.3354/meps07002 Passarelli, C., Olivier, F., Paterson, D.M., Hubas, C., 2012. Impacts of biogenic structures on benthic assemblages: Microbes, meiofauna, macrofauna and related ecosystem functions. Mar. Ecol. Prog. 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Assess. 56, 305–330. https://doi.org/10.1023/A:1005936627590 Sedano, F., Florido, M., Rallis, I., Espinosa, F., Gerovasileiou, V., 2019. Comparing sessile benthos on shallow artificial versus natural hard substrates in the Eastern Mediterranean Sea. Mediterr. Mar. Sci., in press. http://dx.doi.org/10.12681/mms.17897 Sedano, F., Marquina, D., Espinosa, F., 2014. Usefulness of meiofauna at high taxonomic levels as a tool to assess Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 63 Chapter 1 harbor quality status. 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Phys. 17, 30162–30176. https://doi.org/10.1039/c5cp05596b Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Local effects of coastal infrastructure 64 Vaselli, S., Bulleri, F., Benedetti-Cecchi, L., 2008. Hard coastal-defence structures as habitats for native and exotic rocky-bottom species. Mar. Environ. Res. 66(4), 395-403. https://doi.org/10.1016/j.marenvres.2008.06.002 Wehkamp, S., Fischer, P., 2013a. The impact of coastal defence structures (tetrapods) on decapod crustaceans in the southern North Sea. Mar. Environ. Res. 92, 52-60. https://doi.org/10.1016/j.marenvres.2013.08.011 Wehkamp, S., Fischer, P., 2013b. Impact of coastal defence structures (tetrapods) on a demersal hard-bottom fish community in the southern North Sea. Mar. Environ. Res. 83, 82-92. https://doi.org/10.1016/j.marenvres.2012.10.013 Yakovis, E.L., Artemieva, A. V., Fokin, M. V., Varfolomeeva, M.A., Shunatova, N.N., 2007. Effect of habitat architecture on mobile benthic macrofauna associated with patches of barnacles and ascidians. Mar. Ecol. Prog. Ser. 348, 117–124. https://doi.org/10.3354/meps07060 Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 65 Chapter 1 Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Local effects of coastal infrastructure 66 CHAPTER 1.2 Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 67 Chapter 1 1.2 The role of substrate composition and roughness in structuring amphipod communities Adapted from: Sedano, F., Navarro-Barranco, C., Guerra-García, J. M., Espinosa, F. (2020). From sessile to vagile: Understanding the importance of epifauna to assess the environmental impacts of coastal defence structures. Estuarine, Coastal and Shelf Science, 235, 106616. https://doi.org/10.1016/j.ecss.2020.106616 Abstract Ocean sprawl is leading to the introduction of multiple artificial structures into the marine environment. However, the biota on these novel habitats differ from that on natural hard substrates. Amphipods, despite their ecological importance, are usually overlooked when comparing benthic assemblages on artificial and natural hard substrates. So as to assess the effects of artificial structures on amphipod assemblage and to identify the main factors involved, the amphipod assemblage structure was studied in five different substrates (seawalls, cubes, acropods, rip-raps and natural rock). Abiotic measurements of each substrate (complexity, rock composition, and age) were related to the ecological patterns. Complexity measurements seemed to affect the amphipod community structure, highlighting the need to consider physical complexity in eco-engineering actions. Amphipod assemblages were also affected by the secondary substrate (sessile biota), suggesting that artificial structures are indirectly shaping amphipod assemblages by firstly shaping the sessile biota. Future research should study the same secondary substrates across different artificial structures to separate the direct effects (caused by the artificial structures) from the indirect effects (caused by the sessile biota). Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Local effects of coastal infrastructure 68 Introduction The vast proliferation of artificial (man-made) structures in the marine environment in the last decades has attracted the attention of researchers in an attempt to understand and assess the ecological implications of the deployment of artificial substrates (Bulleri and Chapman, 2010; Firth et al., 2016). The potential effects of artificial structures in marine communities have been mainly studied on the basis of the sessile fauna or conspicuous intertidal organisms (Browne and Chapman, 2011; Moreira et al., 2006; Moura et al., 2008). The sessile biota established on artificial structures clearly differ from those found on nearby natural rocky shores, but the potential cascading effects (e.g. facilitation or inhibition of certain vagile species) of these changes on the rest of the community remain largely unknown (Bulleri et al., 2005; Thomsen et al., 2010). These species, acting as secondary substrates, transform bare or simple surfaces into highly structured environments which, in turn, support a wide range of other sessile and mobile species (Bruno and Bertness, 2001; Ólafsson, 2016). Although some taxa can replace the ecological function (e.g. similar trophic groups) of others (e. g Chintiroglou and Antoniadou, 2009 and references therein) it is known that secondary substrates attached to different types of structures can host different macroinvertebrate assemblages (People, 2006). Epifaunal communities, usually including a great variety of small crustaceans, polychaetes and molluscs, are very important ecologically (e.g. Seed and O’Connor, 1981). However, they are often overlooked because (1) sorting all the epifauna from the samples requires great time and effort, (2) identification of many taxa is still challenging and, therefore, meticulous examination and taxonomical expertise is required to guarantee a correct identification of the species. Thus, few studies on artificial habitats consider these vagile assemblages (Carvalho et al., 2013; Moura et al., 2008). Furthermore, when epifauna is considered, it is common to appeal to “High-Taxonomic groups” (HTGs) (Otero-Ferrer et al., 2019; Timms et al., 2013). Indeed, regarding taxonomic sufficiency, studies considering different levels of taxonomic resolution (species, family, order) often show similar results regarding community distributions and the associated environmental variables (Sánchez-Moyano et al., 2006). However, many Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 69 Chapter 1 studies have shown that identification to the species level is mandatory for properly detecting ecological differences in anthropogenic perturbance scenarios (e.g. Guerra-García and GarcíaGómez, 2005). Comprising almost ten thousand species worldwide, Amphipod crustaceans are among the most diverse and numerically dominant organisms of benthic assemblages (Dauby et al., 2001; Guerra-García et al., 2011b). They often account for up to 80% of the total mobile epifauna inhabiting macroalgae and other sessile invertebrates, both in natural and artificial habitats (e.g. Fernández-Romero et al., 2017; Gavira-O’Neill et al., 2016; Navarro-Barranco et al., 2018). They are important contributors to benthic production (Mancinelli and Rossi, 2002; Taylor, 1998) and play a relevant role in trophic nets, being an important component of the diets of fish (Doornbos and Twisk, 1987) or other invertebrates like crabs (Kurihara and Okamoto, 1987; Matsumasa and Shiraishi, 1993). Indeed, their potential use as a resource in aquaculture due to their high content in proteins and omega 3 fatty acids is being explored (Baeza-Rojano et al., 2014; Woods, 2009). Amphipods are mainly detritivores and therefore are suitable candidates for Integrated Multitrophic Aquaculture (IMTA) systems (Fernández-González et al., 2018; Guerra-García et al., 2016). Furthermore, amphipods are considered a valuable tool for detection of anthropogenic impacts since they have been successfully used as bioindicators in industrial areas (Conradi et al., 1997), of oil pollution (Gómez-Gesteira and Dauvin, 2000), of TBTs residues (Takeuchi et al., 2001), of trace metal contamination (Guerra-García et al., 2010), of desalination brine discharges (De-la-Ossa-Carretero et al., 2016), and of light pollution (Navarro-Barranco and Hughes, 2015), and therefore included in biotic indexes (e.g. polychaetes/amphipod ratio, Dauvin, 2018). On the other hand, amphipods are frequently associated to fouling communities and are prone to transportation by recreational boating or aquaculture practices; therefore, they are also used as a model in the study of marine invasions (e.g. Ros et al., 2015). However, the potential value of amphipods for assessing the effects of different artificial structures such as seawalls, cubes, acropods and rip-raps, remains unexplored. Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Local effects of coastal infrastructure 70 In the present study we selected the amphipod community, using a species level identification approach, as a model to understand the macrofaunal variation between natural and artificial substrates (seawall, cubes, acropods and rip-raps) evaluating how this variety of artificial habitats can modify natural epifaunal communities. Different artificial structures are expected to have different abiotic attributes, which directly or indirectly could affect epifaunal communities. Furthermore, most epifaunal taxa need a secondary substrate (sessile) to attach to, that in turn shapes the composition of the whole epifaunal assemblage (Kelaher, 2002; Ólafsson, 2016; Symstad et al., 2000; Torres et al., 2015). This is dependent on the taxa composition of the sessile component, the quality and amount of resources provided (e.g. food, habitat, refuge against desiccation) and the morphological and biological features of such secondary substrates (e.g. complexity, epiphytic load, presence of chemical defences or life cycle) (Ólafsson, 2016). Thus, potential differences in the epifaunal community among different types of artificial habitats are expected to reflect patterns in taxa composition and/or substrate cover of the sessile community. Therefore, our hypothesis is that amphipod assemblages will differ among artificial substrates and in comparison with natural ones, and that those differences (community structure and diversity) will be related with the features of the primary (artificial structures) and the secondary (sessile community) substrates. Invertebrate assemblage structure at the regional scale has little predictability (Simpson et al., 2017) and regional differences can confound the effects of artificial substrates (Gacia et al., 2007). Consequently, we have selected Algeciras Bay (South Spain) as a study site since this unique location encompasses different types of artificial substrates within an area of 1.5 km, and which are therefore expected to be subjected to similar environmental conditions, thus avoiding potential confounding effects. Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 71 Chapter 1 Materials and methods Study area Samples were collected in different coastal defence structures of the Algeciras harbour and the nearest natural hard substrate (Fig. 1). The harbour is located on the West side of Algeciras Bay (Strait of Gibraltar, southern Spain) and is one of the biggest harbours in Europe, surpassing 100 mT of freight in 2017 (www.ec.europa.eu/eurostat/). Due to intense shipping activities and the presence of industries such as paper mills, refineries, thermal power plants, iron works, and chemical factories (Conradi et al., 1997), this bay has been the focus of numerous studies (Guerra-García et al., 2010). To avoid heterogenous environmental conditions, we chose substrates located in the surroundings of Algeciras Harbour with a maximum distance of 1.5 km between them. Previous studies in Algeciras Bay have shown similar annual averages of hydrodynamism, suspended solids, silting, organic matter and temperature (Carballo et al., 1996; Naranjo et al., 1996). Fig. 1. Location of Algeciras Bay in the Strait of Gibraltar showing the five sampling stations. Seawall, acropod and cubes were concrete-based while the rip-rap was natural rock-based. 1: Seawall; 2: Cube; 3: Acropod; 4: Rip-rap; 5: Natural. Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Local effects of coastal infrastructure 78 Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 79 Chapter 1 In contrast, seawalls were numerically dominated by Stenothoe eduardi, Jassa marmorata and Ampithoe riedli; on the contrary, species that were abundant in other substrates (e.g. S. monoculoides and C. grandimana) were completely absent from seawalls. Regarding acropods, Hyale perieri was the only species that was clearly more abundant than other taxa. Differences in assemblage structure (species composition and abundances) among substrates were further confirmed by PERMANOVA (Table 4). There were significant differences in the volumes of each replicate. Amphipod assemblage structure significantly differed among substrates except for cubes and acropods (see pair-wise tests in Table 4). Factor “Site” was also significant and pair-wise tests (data not shown) revealed that it was due to a single difference between ‘natural site 2’ and ‘natural site 3’ mainly caused by differences in the abundance of dominant species (e.g. Caprella penantis, J. marmorata, Stenothoe tergestina). In fact, factor “Site” was not significant when presence/absence data was considered. Differences were also graphically portrayed by the dendrogram (Fig. 2A), where the different substrates were segregated in four groups (at a similarity level of 40%). Interestingly, the segregation of sites in the dendrogram Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Local effects of coastal infrastructure 80 was somehow concordant with the more abundant sessile taxon/taxa in terms of volume at each site (Fig. 2B). In fact, there were high correlation values (Table 5) among some amphipods and certain sessile species, independent of the primary substrate (i. e. habitat): S. eduardi and J. marmorata correlated with M. galloprovincialis and P. perforatus, while S. monoculoides and L. websteri correlated with E. elongata and J. rubens. On the other hand, other numerically dominant taxa such as Elasmopus spp. and C. grandimana did not show any preference for the secondary substrate. Table 4: PERMANOVA table of results for amphipod assemblage (based on taxa composition and abundances). Ha: Habitat [five levels: N (natural rocky shore), R (rip-rap), A (acropod), C (cube) and SW (seawall)]; Si (Ha): Site nested to Habitat; CO: covariate (volume of secondary substrate); df: degrees of freedom; MS: mean square; p: level of significance; *: p < 0.05; ***: p < 0.001. Amphipod assemblage Source of variation df MS Pseudo-F p CO 1 22414 16.412 *** Ha 4 7597 5.2758 *** Si (Ha) 10 1502.6 1.3766 * Residual 29 1091.6 Total 44 Pair-wise tests Levels of factor Ha: N≠(A,C,SW,R), SW≠(A,C,R), C≠R, A≠R Levels of factor Si (Ha): Only difference detected between ‘natural site 2’ and ‘natural site 3’. According to SIMPER analysis (Table 6), rip-raps were the least dissimilar substrate compare to natural ones (48.85% average dissimilarity) while seawalls were the most dissimilar substrate (64.17% average dissimilarity). Stenothoe monoculoides, H. stebbingi and L. websteri were always the species that contributed more to the dissimilarity between the natural and artificial substrates. Results of dbRDA (Fig. 4, Table 7) yielded a model of abiotic variables (macro, micro, crystall., age and magnesium) that significantly explained (p < 0.01) 65.7% of the total inertia but according to the marginal effects, only micro-scale roughness was significantly correlated with the amphipod composition. According to dbRDA plots, the vectors of the drivers showed the importance of crystallinity, age and macro scale roughness for the assemblage of the natural rocky shore. Similarly, those were also the principal drivers for the assemblage of seawalls, that had very different amphipod assemblages compared to natural Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 81 Chapter 1 ones. The results also represent that the main driver for rip-raps, acropods and cubes was microscale roughness. Table 5: Values of Spearman’s correlation coefficient among selected amphipod and sessile species. Only amphipods that had high contributions (> 5.99 %) to dissimilarity between natural and each of the artificial substrates are included. Shaded cells indicate high correlations (> 0.7). H. stebbingi S. monoculoides S. eduardi J. marmorata Elasmopus spp. L. websteri C. grandimana E. elongata 0.364 0.878 0.044 0.173 0.489 0.881 -0.016 M. galloprovincialis -0.420 -0.360 0.756 0.859 -0.222 -0.270 -0.314 P. perforatus -0.533 -0.477 0.641 0.744 -0.317 -0.352 -0.310 S/D reef 0.128 0.545 -0.069 -0.336 0.449 0.716 -0.120 J. rubens 0.277 0.703 -0.001 -0.132 0.359 0.966 -0.043 When using the sessile community as a predictor variable, dbRDA results provided a highly significant (p < 0.001) model that explained 82.3% of the total inertia (Table 7). Only the marginal effect of E. elongata was significantly correlated with the amphipod assemblages. The assemblage on the natural rocky shore was separated from the artificial ones, correlating with E. elongata, J. rubens, Ceramium sp., Spirobranchus sp./Dendropoma sp. reef, Laurencia sp. and L. incrustans (Fig. 4). The assemblages of artificial substrates were separated in two main groups along axis 1, with the seawalls’ assemblage correlated with M. galloprovinciallis, Ulva sp. and R. okamurae. Table 6: Results of SIMPER analysis comparing amphipod composition in the natural rocky shore site with each of the four artificial substrates. Only dominant species are included. Av.Diss: Average dissimilarity; SD: standard deviation; Contrib.: contribution to dissimilarity. Amphipod assemblage Groups Natural & Rip-rap Average dissimilarity = 48.85 % Groups Natural & Acropod Average dissimilarity = 58.17 % Species Av.Diss. ± SD Contrib.% Species Av.Diss. ± SD Contrib.% S. monoculoides 10.55 ± 1.67 21.60 S. monoculoides 16.13 ± 2.78 27.73 H. stebbingi 5.51 ± 1.42 11.27 H. stebbingi 7.12 ± 1.44 12.24 L. websteri 3.77 ± 2.47 10.45 L. websteri 5.60 ± 1.91 9.62 Elasmopus spp. 3.04 ± 1.48 7.73 S. eduardi 3.32 ± 1.60 5.72 Groups Natural & Cube Average dissimilarity = 64.01 % Groups Natural & Seawall Average dissimilarity = 64.17 % Species Av.Diss. ± SD Contrib.% Species Av.Diss. ± SD Contrib.% S. monoculoides 16.65 ± 2.29 26.01 S. monoculoides 19.59 ± 4.37 30.52 L. websteri 7.41 ± 3.04 11.58 H. stebbingi 8.24 ± 1.72 12.84 H. stebbingi 6.20 ± 1.41 9.69 L. websteri 7.00 ± 3.16 10.90 C. grandimana 4.27 ± 1.23 6.67 C. grandimana 4.24 ± 2.52 6.60 J. marmorata 3.84 ± 1.78 5.99 Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Local effects of coastal infrastructure 82 Discussion Overall, our results support the main hypothesis that this natural rocky intertidal coast harbours a different amphipod assemblage in comparison to the assemblage present on coastal defence structures. Differences were also found among different types of artificial structures (except for the comparison between cubes and acropods). Differences at the community structure level have been widely reported (Firth et al., 2016) for sessile fauna but few studies have taken into account the vagile fauna, and the amphipod assemblage in particular (Moura et al., 2008). The increasing armouring of the coast is replacing important functions (Dugan et al., 2011; Gittman et al., 2016) of natural habitats such as acting as nursery grounds for juvenile fish. Although eco-engineering measures are aiming to restore the conditions sustained by natural habitats (Perkins et al., 2015) providing multifunctional approaches (Dafforn et al., 2015; Strain et al., 2017), new measures should take into account the important role of vagile fauna. Indeed, amphipods and polychaetes constitute an important food source for fish associated with artificial structures (Duffy-Anderson and Able, 2001; Munsch et al., 2015). Cordell et al. (2017) stated that piers held less diverse invertebrate assemblages that in turn affect the availability of fish’s prey. This concurs with our results; in fact, artificial substrates held less amphipod taxa and smaller total average abundances compared to the natural rocky shore. Therefore, this could affect the availability of prey depending on the substrate type (Munsch et al., 2015). The natural rocky shore had significantly higher total amphipod abundance that also translated into a higher number of amphipod taxa. In contrast, among artificial substrates, rips-raps showed the highest amphipod abundance, but the number of amphipod taxa was similar in comparison to the other artificial substrates, suggesting that the amphipod assemblage on the artificial structures was more homogenous (Firth et al., 2016) and that the occurrence of new taxa was not dependent on the amphipod abundance. Rip-raps shared with the natural rocky shore 15 out of 20 amphipod taxa identified. As a consequence, rip-raps were the most similar (according to similarity percentages) to the natural rocky shore while the seawall was the least similar. Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 83 Chapter 1 Rip-raps have been previously identified as poor surrogates of natural rocky shores (Gacia et al., 2007; Moschella et al., 2005; Sedano et al., 2019) but according to our results, rip-raps seem to perform better than concrete-based substrates (cubes, acropods and seawall). The benefits of incorporating boulder habitats (e.g. rip-raps) have been reviewed by Liversage and Chapman (2018) and furthermore, a meta-analysis by Gittman et al. (2016) showed no differences between rip-raps and natural substrates. The higher similarities between rip-raps and natural habitats may be due to the fact that the former is the only studied artificial substrate built with natural rock. Concrete-based structures are known to raise pH levels and exude toxic components (Ido and Shimrit, 2015) that may stress the associated assemblages, although this Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Local effects of coastal infrastructure 84 may be more relevant for sessile species. Within abiotic variables, only micro-scale roughness significantly correlated with the amphipod assemblage. In agreement with our results, a previous experiment focused on ecological engineering revealed the positive response of mobile epibiota (including several families of amphipods) to increasing small-scale complexity of artificial substrates (Lavender et al., 2017). Higher micro-scale roughness can increase refuge availability against stressful environmental conditions and predators (Loke et al., 2017; Strain et al., 2018) giving a competitive advantage to free living or cavity dwelling amphipods. This could be the case of H. stebbingi, a species that normally lives tightly associated with algae (Guerra-García et al., 2011a; Izquierdo and Guerra-García, 2011). Hyale stebbingi did not correlate with any sessile substrate and was also abundant on cubes, where the phytal substrate was scarce, maybe taking advantage of the highly complex pits and crevices that are colonized by turf algae such as Ceramium sp. and Gelidium sp. In contrast, Hyale perieri was abundant on acropods. H. perieri is well adapted to phytal substrates (Scipione, 2011) and can inhabit upper levels of the intertidal that are heavily affected by desiccation (Guerra-García et al., 2011a). It also presents cavity dwelling behaviour and is known to live in association with molluscs (Vader, 1972). Furthermore, this species can reach bigger sizes than H. stebbingi, and potentially outcompete the latter in smoothed substrates such as acropods and seawalls. However, further experimental approach would be needed to confirm this hypothesis. Age, macro-scale roughness and crystallinity were also identified as the main drivers of the assemblages associated with the natural rocky shore and seawalls. The natural rocky shore was rich in quartz and therefore had a more crystalline mineral structure than other substrates, promoting micro-textured surfaces. Berntsson et al. (2000) related micro-textured surfaces with a reduction of 92% in settlement and recruitment of barnacles compared to smooth surfaces. This may explain the scarce presence of barnacles in the natural rocky shore. Along with our results, alkaline cements are known to boost the recruitment of barnacles in concrete structures (Guilbeau et al., 2003) and therefore the absence of cement could explain the scarce presence of barnacles in rip-raps. Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 85 Chapter 1 Our results support one of the initial hypotheses: sessile substrates play a key role in the observed differences in amphipod structure between habitats (both natural and artificial). In fact, the dbRDA using the sessile community as an explanatory variable, yielded a highly significant model that accounted for 82.3% of the total inertia suggesting a tight relationship between the secondary substrates and the amphipod assemblages. Ellisolandia elongata and Mytilus galloprovincialis were the most abundant secondary substrates found in this study. They provided large volumes of habitable substrate for epifauna, but with different surface complexity and therefore different surface area available for colonization (Loke and Todd, 2016). Measurements of the fractal dimensions (D) of E. elongata and Mytillus beds have provided different results (Kostylev et al., 1997; Commito and Rusignuolo, 2000; MartínezLaiz et al., 2018). The difference in this morphological measure between E. elongata and M. galloprovincialis provides different refuge size and different water retention capabilities, therefore, it could be an important factor driving the development of different intertidal amphipod assemblages between substrates. The most abundant amphipod species in the natural rocky shore was Stenothoe monoculoides, a small amphipod well adapted to live on phytal substrates such as E. elongata (Izquierdo and Guerra-García, 2011). Its abundance correlated well with E. elongata while S. eduardi presented the opposite pattern by correlating with M. galloprovincialis. Stenothoe eduardi is bigger than S. monoculoides, is known to inhabit within the cavity of other invertebrates (Krapp-Schickel and Vader, 2015) and is also a good competitor under high sedimentation rates (Lattanzi et al., 2013). Indeed, we observed a higher retention of sediment (personal observation) in the samples with high abundances of filter feeding species (i.e. mussels and barnacles on the seawall). These may have permitted a better adaptation of S. eduardi to the environment present on the seawall. Similarly, Yakovis et al. (2007) highlighted how the cavity-loaded structures of barnacles can shape the associated macrofauna. The different habitat distribution showed by S. monoculoides and S. eduardi, as well as the almost opposite patterns of abundance reported above for H. stebbingi and H. perieri, points out the relevance of species-level identification. Epifaunal responses to environmental perturbations Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Local effects of coastal infrastructure 86 often occur in very complex and specific ways, so that many ecological impacts can be easily overlooked when many different taxa are grouped as simple higher taxonomical units (Maggi et al., 2015; Navarro-Barranco et al., 2019). In a similar way to S. eduardi, abundance of the suspension feeder J. marmorata correlated with the abundance of mussels and barnacles. As shown in our results, J. marmorata is considered an opportunistic species well adapted to anthropized environments and a very quick colonizer (Beermann and Franke, 2012). The sediment, useful as a binder (Kronenberger et al., 2012), accumulated between the spaces of barnacles and mussels, and the wide surfaces of mussels could provide a suitable substrate for the development of tube-builders, similar to that found by Aikins and Kikuchi (2001) that related higher abundance of tube-builders in broad foliate thalli of algae. Furthermore, the vertical seawalls dissipate wave energy deficiently (Jung et al., 2012) and the construction of tubes may present an advantage over free living species. In contrast, L. websteri, another tube-builder, was absent from seawalls and barely present in the other artificial substrates; however, it was very abundant in natural ones, probably due to its low tolerance to stress as it is indicated by its inclusion in the AZTI Marine Biotic Index (AMBI - List of June 2017) (Borja et al., 2000). Contrarily, some species did not show a close relationship with the secondary substrate and their occurrence in a particular substrate could be more related to other abiotic variables (e.g. the abovementioned case of Hyale species) such as substrate roughness or the surrounding environment, rather than the availability of a suitable secondary substrate to attach. In a similar way, Navarro-Barranco et al. (2015) suggested that different sessile invertebrates played equivalent facilitation roles over amphipod assemblages (non-host specialists) indicating that different sessile substrates could have comparable host functions (Bates and DeWreede, 2007; Saarinen et al., 2018). However, Navarro-Barranco et al. (2015) studied subtidal assemblages inhabiting a marine cave under presumably less stressful conditions than those found in our intertidal scenario, where some species presented tight relationships with the sessile taxa, suggesting that the occurrence or dominance on artificial substrates of certain species could be driven by species-specific facilitation processes (Bulleri et al., 2016). Therefore, our results Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 87 Chapter 1 could be reflecting the importance of diverse secondary substrates (e.g. with different morphological complexities) in hosting different assemblages under stressful conditions. In accordance to this, Saarinen et al. (2018) found that intertidal communities dominated by foliose algae held a different amphipod assemblage when compared to the controls (eight seaweed species of different functional groups) demonstrating that the identity of the secondary substrate was important under stressful abiotic conditions. Interestingly, we did not find any non-indigenous species (NIS) in the artificial substrates of the present study. However, other studies conducted inside marinas from nearby areas have reported several NIS inhabiting artificial substrates (e.g. floating pontoons) (Ros et al., 2013a). Fouling transport associated to recreational boating between marinas seems to be an effective vector for the establishment of exotic amphipods within them, but not in the surrounding substrates outside (Ros et al., 2013b). This suggests that exotic amphipods remain concentrated inside the marinas even when there are available artificial substrates to colonize outside. It is also worth noting that it is not only the distinctiveness of the artificial substrate (or its secondary effects), but also its accessibility that could partially affect the successful establishment of certain species. For example, the caprellids Caprella grandimana and C. penantis were absent on the seawall, which is the only substrate not connected to mainland. Therefore, their absence could be related to their reduced swimming capability (due to reduction of pleopods) in comparison with other amphipod families (Takeuchi, 1998), as well as the inability of the abovementioned species to be dispersed by rafting or attached to fouling communities. The connectivity of offshore structures may have a relevant role in facilitating the proper colonization by surrounding species. This colonization impediment may lead to comparatively impoverished amphipod assemblages on offshore artificial substrates that could be easily outcompeted by opportunistic species. Sanabria-Fernández et al. (2018) pointed out the relevance of species mobility in the colonization of breakwaters. Biodiversity loss (in comparison with nearby natural habitats) was higher for those species with lower mobility. Therefore, eco-engineering actions directed to facilitate the establishment of native Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Local effects of coastal infrastructure 94 Ros, M., Guerra-García, J.M., González-Macías, M., Saavedra, Á., López-Fe, C.M., 2013a. 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Large scale variability in the structure of sessile invertebrate assemblages in artificial habitats reveals the importance of local-scale processes. J. Exp. Mar. Biol. Ecol. 494, 10–19. https://doi. org/10.1016/j.jembe.2017.05.003. Strain, E.M.A., Morris, R.L., Coleman, R.A., Figueira, W.F., Steinberg, P.D., Johnston, E. L., Bishop, M.J., 2018. Increasing microhabitat complexity on seawalls can reduce fish predation on native oysters. Ecol. Eng. 120, 637–644. https://doi.org/10.1016/j.ecoleng.2017.05.030. Strain, E.M.A., Olabarria, C., Mayer-Pinto, M., Cumbo, V., Morris, R.L., Bugnot, A.B., Dafforn, K.A., Heery, E., Firth, L.B., Brooks, P.R., Bishop, M.J., 2017. Eco-engineering urban infrastructure for marine and coastal biodiversity: which interventions have the greatest ecological benefit? J. Appl. Ecol. 55, 426–441. https://doi.org/10.1111/1365-2664.12961. Symstad, A.J., Siemann, E., Haarstad, J., 2000. An experimental test of the effect of plant functional group diversity on arthropod diversity. Oikos 89, 243–253. Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 95 Chapter 1 Takeuchi, I., 1998. Is the Caprellidea a monophyletic group? J. Nat. Hist. 27, 947–964. https://doi.org/10.1080/00222939300770581. Takeuchi, I., Takahashi, S., Tanabe, S., Miyazaki, N., 2001. Caprella watch: a new approach for monitoring butyltin residues in the ocean. Mar. Environ. Res. 52, 97–113. Taylor, R.B., 1998. Density , biomass and productivity of animals in four subtidal rocky reef habitats: the importance of small mobile invertebrates. Mar. Ecol. Prog. Ser. 172, 37–51. Ter Braak, C.J.F., 1988. CANOCO-a FORTRAN Program for Canonical Community Ordination by [partial][detrented][canonical] Correspondence Analysis, Principal Components Analysis and Redundancy Analysis (Version 2.1). Ministerie van Landbouw en Visserij, Wageningen, AC. Ter Braak, C.J.F., Smilauer, P., 1998. CANOCO Reference Manual and User’s Guide to Canoco for Windows: Software for Canonical Community Ordination (Version 4). Centre for Biometry, Wageningen, AC. Thomsen, M.S., Wernberg, T., Altieri, A., Tuya, F., Gulbransen, D., Mcglathery, K.J., Holmer, M., Silliman, B.R., 2010. Habitat Cascades : the conceptual context and global relevance of facilitation cascades via habitat formation and modification. Integr. Comp. Biol. 50, 158–175. https://doi.org/10.1093/icb/icq042. 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Valverde, J.M., Perejon, A., Pérez-Maqueda, L.A., 2015. Thermal decomposition of dolomite under CO 2 : insights from TGA and in situ XRD analysis. Phys. Chem. Chem. Phys. 17, 30162–30176. https://doi.org/10.1039/c5cp05596b. Woods, C.M.C., 2009. Caprellid amphipods: an overlooked marine fin fish aquaculture resource? Aquaculture 289, 199–211. https://doi.org/10.1016/j. aquaculture.2009.01.018. Yakovis, E.L., Artemieva, A.V., Fokin, M.V., Varfolomeeva, M.A., Shunatova, N.N., 2007. Effect of habitat architecture on mobile benthic macrofauna associated with patches of barnacles and ascidians. Mar. Ecol. Prog. Ser. 348, 117–124. https://doi.org/ 10.3354/meps07060. Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Regional effects of coastal infrastructure 96 CHAPTER 2: Is the impact of coastal infrastructure constant at regional level? Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 97 Chapter 2 2.1 Coastal armouring produces intertidal biodiversity loss across the Alboran Sea (western Mediterranean Sea) General hypothesis: Intertidal biodiversity loss will be observed at every artificial structure and locality independently of substrate type across the Alboran Sea. Seawalls will have the lowest ecological value while rip-raps will have the highest. The expected patterns will be influenced by the spatial scale of the study, the environmental gradient presented in the area and the individual local conditions. 2.2 Algae canopy and biodiversity loss on Crete’s rip-raps (Greece) General hypothesis: Biodiversity will be lower on rip-raps in comparison with natural rocky shores across the island independently of locality or orientation (north/south). Community structure and function (in terms of macroalgal structural complexity) will differ between natural and artificial substrates, having the latter an impoverished algal canopy. Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Regional effects of coastal infrastructure 98 CHAPTER 2.1 Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 99 Chapter 2 2.1 Coastal armouring produces intertidal biodiversity loss across the Alboran Sea (western Mediterranean Sea) Adapted from: Sedano, F., Pavón, A., Navarro-Barranco, C., Guerra-García, J.M., Digenis, M., Sempere-Valverde, J., Espinosa, F. (Submitted to journal). Coastal armouring produces intertidal biodiversity loss across the Alboran Sea (western Mediterranean Sea). Ecological Engineering. Abstract Intertidal ecosystems are key habitats that are being replaced by artificial hard substrates due to the increment of human activities in coastal areas. These new substrates are generally less biodiverse due to differences in complexity and composition among others. This biodiversity loss is a global phenomenon and has led to the development of mitigating strategies in the framework of eco-engineering. However, mitigating measures, such as new eco-designs, must cope with the high spatial variability of the region where they are applied. Therefore, in order to asses if the biodiversity loss detected at local scales in previous studies could be scaled up to predict patterns at a wider scale, we studied taxa richness and taxonomic structure of intertidal communities across the Alboran Sea (western Mediterranean Sea). We compared four different types of artificial substrates (cubes, rip-raps, seawalls and tetrapods) to assess which produces less impact. Overall, there was a biodiversity loss on artificial substrates across the Alboran Sea. This loss was minimized on boulder-like artificial structures, specially on ripraps, while it was maximized on seawalls. Nevertheless, the effect of a particular type of artificial structure at a regional scale seems unpredictable, highlighting the challenge that ecoengineering measures face in order to establish global protocols for biodiversity enhancement and the importance of local scale in management programmes. Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Regional effects of coastal infrastructure 100 Introduction Intertidal ecosystems are important areas due to their high ecological value and numerous services provided (Branch et al., 2008; Cacabelos et al., 2019) but at the same time they are threatened by climate change and anthropogenic alterations. The sea level rise coupled with the increasing use of coastal areas by a range of human activities (commercial, touristic and recreational) is leading to the destruction, pollution and overexploitation of intertidal ecosystems (Bulleri et al., 2005; Firth et al., 2016a; Helmuth et al., 2006). One of the biggest impacts is the replacement of natural shores or addition of new hard substrates (Gittman et al., 2016). These new substrates are usually concrete defence infrastructures such as seawalls or boulders that currently cover a considerable number of European coasts (Beck and Airoldi, 2007; Ido and Shimrit, 2015). They are generally considered less biodiverse than the natural substrates they replace (see Firth et al., 2016a for a review) due to differences in composition, substrate complexity and surface inclination among others (Coombes et al., 2015; Ido and Shimrit, 2015; Loke et al., 2015; Moreira et al., 2006). Specifically, the lack of complexity and extreme steep inclination of seawalls can limit the number of taxa that recruits or survive on them (Bulleri, 2005). Due to the reduction of intertidal space and higher competition on seawalls, the populations of some limpets have been compromised (Moreira et al., 2006). Lai et al. (2018) suggested that the steep slope of seawalls diminishes the primary productivity potential, limiting the populations of grazers, specially gastropods that feed on turf algae. Seawalls are often more exposed and dissipate wave action less efficiently than boulder habitats, promoting the preferential establishment of certain taxa, such as filter feeding organisms (Sedano et al., 2020a), contributing also to the homogenization of intertidal communities (Firth et al., 2016). For these reasons, seawalls are one of the least ecologically valuable artificial structures, which has attracted the attention of researchers who look for mitigation measures in the framework of eco-engineering (Browne and Chapman, 2011; Loke et al., 2017; Moreira et al., 2007). Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 101 Chapter 2 In contrast, boulder habitats can be occupied by more species since they have gentler slopes and higher structural complexity than seawalls (Liversage and Chapman, 2018). For example, the presence of tide pools (Evans et al., 2016; Ostalé-Valriberas et al., 2018) and shady sheltered environments (Sherrard et al., 2016) can favour more diverse communities and even increase the presence of rare or endangered species (García-Gómez et al., 2011) or taxa of commercial importance (Liversage and Chapman, 2018). Consequently, boulder-like artificial structures made of natural rock (rip-raps) have been considered as better surrogates of natural substrates in comparison with other artificial substrates such as concrete cubes or seawalls (Sedano et al., 2020a). Furthermore, the benefits of incorporating boulder habitats in ecological engineering have been reviewed by Liversage and Chapman (2018). However, one of the biggest challenges for coastal managers and environmental policers is the establishment of measures, protocols or ecological designs in this case, that can be applied at great geographical scales in an integrative way (Sanó et al., 2010). Patterns in nature are intrinsically scale dependent (Terlizzi et al., 2007) and, based on the spatial scale, differences in community structure may be more or less evident (Wiens et al., 1993). This, together with the high spatial variability presented by many taxa, complicates the reliable description of anthropogenic impacts associated with introduced artificial structures (Bishop et al., 2002; Lanham et al., 2018). Therefore, in order to asses if the biodiversity loss associated with artificial substrates detected at local scales in previous studies (Sedano et al., 2020a; 2020b) could be scaled up to predict patterns at a wider scale (Wooton, 2001), we studied the taxa richness ,taxonomic structure (composition of taxa according to their presence/absence) and taxa cover percentages (on vertical exposed surfaces) of intertidal communities across the Alboran Sea (western Mediterranean Sea). Our study included the description of biodiversity patterns on four types of artificial substrates (cubes, rip-raps, seawalls and tetrapods), which were related with abiotic variables of each substrate and their location with the aim of identifying the drivers of biodiversity differences. More specifically, we hypothesized that: 1) Intertidal richness will be lower on artificial substrates in comparison with their nearest natural rocky substrates. This pattern will be observed at every locality Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Regional effects of coastal infrastructure 102 independently of substrate type across a high spatial scale (i.e., across the Alboran Sea). 2) Taxonomic structure and cover of species will also differ between natural and artificial substrates. We expect that seawalls will have the lowest ecological value and therefore will be the worst surrogates of natural substrates. We also expect that due to their higher complexity and natural composition, rip-raps will be the best surrogates of natural substrates. 3) The expected patterns will be influenced by the spatial scale of the study, the environmental gradient presented in the area and the individual local conditions. Materials and methods Biotic and abiotic data collection In May 2017, we carried out a photographic sampling of four different artificial substrates (three concrete-based: cubes, seawalls and tetrapods, and one natural rock-based: rip-raps) and their nearest natural rocky substrates along the coast of the Alboran Sea (western Mediterranean Sea (Fig. 1, Table 1). Photographs were taken at low intertidal level (5-30 cm over the lowest tidal level). Fig. 1: Sampling map portraying the type of artificial structure sampled at each locality. Note that the closest natural substrate to Marina Smir and M’Diq was the same and that in Motril we sampled two adjacent artificial structures (cubes and seawall). Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 103 Chapter 2 Two complementary methodologies were conducted. (i) Taking into account that each kind of substrates can provide different exposure, slope, orientations and microhabitats, global quantitative comparison can be difficult among substrates. Therefore, to properly compare the whole taxonomic structure (taxa composition according to their presence/absence) among substrates (including non-exposed areas, shady places, overhangs, crevices, etc.), we performed three ten-minute transects per substrate at each locality to try to find and photograph as much species as possible. This methodology is an adaptation from the commonly used time transects for bird watching (Hyrenbanch et al., 2007; Van der Meer and Leopold, 1995). In contrast with photoquadrats (used in our second methodology), the use of time transects greatly reduces data collection and post-collection computer analyses of digital photographs (Preskitt et al., 2004), which was a clear advantage for us given the long distance (and the number of replicates) covered in this study. However, using this methodology we could characterised the global intertidal macrobenthic diversity of each substrate, but we could not compare the cover of the different species. (ii) Therefore, to get quantitative data of covers comparable among substrates, we took 15 photoquadrats on vertical exposed faces of each substrate for each locality. The experimental design for each methodology was: i: Factor Substrate (Su), two levels (artificial, natural), fixed; Factor Locality (Lo), three levels, random and orthogonal with Su. On each substrate, the three 10-minute transects were allocated with tens of metres of separation (20 m to 50 m depending on the length of the substrate). ii: Factor Substrate (Su), two levels (artificial, natural), fixed; Factor Locality (Lo), three levels, random and orthogonal with Su; and factor Site (Si), three levels, random and nested in Su and Lo. Five 20x20 cm quadrats were photographed at each site. Photos were taken using an Olympus TG4 camera with a Subacqua Helios 1700 focus light. Cover of sessile species was measured by spawning 75 random points using PhotoQuad software (Trygonis and Sini, 2012). Taxa that were present in the photoquadrats but did not fall below a random point were given an arbitrary value of 0.5% cover (Bacchiocchi and Airoldi, 2003; Marzinelli et al., 2011; Ostalé-Valriberas et al., 2018). Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Regional effects of coastal infrastructure 110 Caulacanthus sp. 100 100 66 100 100 Dichotomic rhodophyta 33 33 0 0 20 Ellisolandia elongata 100 100 33 100 100 Encrusting red algae 100 100 33 100 80 Foliose rhodophyta 0 33 0 0 10 Gastroclonium sp. 0 0 0 0 40 Gelidium sp. 100 66 0 0 90 Hildenbrandia sp. 100 66 33 66 80 Jania rubens 0 0 0 0 90 Lithophyllum byssoides 0 33 0 0 10 Nemalion sp. 33 0 0 0 20 Pyropia sp. 66 33 0 0 50 Rhodomelaceae 33 0 0 0 30 Rissoella verruculosa 0 0 0 0 30 Turf forming rhodophyta 100 33 33 0 40 Porifera Clathrina rubra 0 0 0 0 10 Orange sponge 33 66 33 66 10 Cnidaria Actinaria sp.1 0 0 0 0 30 Actinaria sp.2 0 0 0 0 10 Actinia equina 100 100 66 100 100 Aglaophenia pluma 0 0 0 0 20 Aiptasia mutabilis 0 0 0 0 10 Anemonia sp. 33 0 0 0 50 Astroides calycularis 33 33 0 66 30 Cereus pedunculatus 0 0 0 0 10 Annelida Serpullidae 0 0 0 0 10 Spirorbinae 0 0 0 0 30 Terebellidae 0 0 0 0 10 Mollusca Acanthochitona sp. 3 0 0 0 10 Cymbula safiana 3 66 33 100 30 Dendropoma sp. 66 33 33 0 70 Echinolittorina punctata 66 33 66 66 40 Fissurellidae 66 66 0 66 60 Gastrochaena dubia 0 0 0 0 10 Littorinidae 0 0 33 0 10 Melarhaphe neritoides 66 33 33 66 40 Myoforceps aristatus 0 0 0 0 20 Mytilus sp. 33 66 66 100 80 Onchidella celtica 0 0 0 0 30 Ostreidae 0 0 33 0 0 Patella ferruginea 66 66 33 66 50 Patella rustica 100 100 66 100 100 Patella spp. 100 100 100 100 100 Perna perna 0 0 0 0 20 Polyplacophora 66 100 0 33 80 Siphonaria pectinata 100 100 100 100 100 Stramonita haemastoma 0 66 33 33 20 Thuridila hopei 0 0 0 0 10 Trochidae 100 66 100 100 83 Vermetus triquetrus 33 0 0 0 20 Arthropoda Chthamalus stellatus 100 100 100 100 100 Eriphia verrucosa 0 0 0 0 20 Pachygrapsus marmoratus 0 33 0 0 40 Perforatus perforatus 66 100 100 66 80 Pollicipes sp. 0 66 0 33 20 Echinodermata Arbacia lixula 66 33 0 0 10 Paracentrotus lividus 0 0 0 0 10 Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 111 Chapter 2 PERMANOVA results (Supplementary Table 7) showed significantly different taxonomic structure (presence/absence data) between substrates (interaction SuxLo). According to the pair-wise tests, the taxonomic structure was different between natural and artificial substrates at every locality except three (Marina del Este [Rip-raps], and Motril [Seawalls and Cubes]) (Fig. 4). This was also graphically portrayed in the MDS (Fig. 4), where a clear segregation between artificial and natural substrates is observed for every type of artificial substrate except for the rip-raps, where it is possible to infer some overlapping. In fact, rip-raps had the most similar taxonomic structure in comparison with the natural substrates (see SIMPER in Table 3). The taxonomic structure of the seawalls was the most dissimilar. Fig. 4: MDS of the taxonomic structure by type of substrate. The dashed boxes contain the results of the pair-wise tests according to PERMANOVA. Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Regional effects of coastal infrastructure 112 Table 3: Results of SIMPER analysis comparing the taxonomic structure between natural and each of the artificial substrates. To summarize the information, only the first thirteen taxa are included. Av.Diss: Average dissimilarity; SD: standard deviation; Contrib.: contribution to dissimilarity. Intertidal taxonomic structure Groups Natural & Rip-rap Average dissimilarity = 36.80% Groups Natural & Cube Average dissimilarity = 45.75% Species Av.Diss. ± SD Contrib.% Species Av.Diss. ± SD Contrib.% J. rubens 1.91 ± 1.82 5.18 Green fil. algae 1.83 ± 1.50 4.00 Trochidae 1.64 ± 1.38 4.47 Ulva sp. 1.76 ± 1.35 3.84 Bangia sp. 1.40 ± 1.09 3.81 J. rubens 1.64 ± 1.35 3.59 Mytilus sp. 1.39 ± 1.09 3.78 Rhodomelaceae 1.60 ± 1.35 3.50 P. rustica 1.37 ± 1.09 3.72 Cystoseira spp. 1.54 ± 1.26 3.36 Pyropia sp. 1.30 ± 1.01 3.52 C. sinuosa 1.48 ± 1.17 3.23 Green fil. algae 1.28 ± 1.01 3.48 Trochidae 1.42 ± 1.08 3.10 Dendropoma sp. 1.12 ± 0.88 3.04 Gelidium sp. 1.41 ± 1.08 3.08 P. perforatus 1.09 ± 0.88 2.96 Mytilus sp. 1.34 ± 1.03 2.92 Hildenbrandia sp. 1.06 ± 0.88 2.88 C. safiana 1.30 ± 1.01 2.85 P. ferruginea 0.90 ± 0.75 2.43 Polyplacophora 1.28 ± 0.95 2.81 Rhodomelaceae 0.86 ± 0.69 2.35 P. perforatus 1.27 ± 0.95 2.78 Nemalion sp. 0.86 ± 0.69 2.35 Pyropia sp. 1.25 ± 0.91 2.73 Groups Natural & Tetrapod Average dissimilarity = 40.58% Groups Natural & Seawall Average dissimilarity = 58.69% Species Av.Diss. ± SD Contrib.% Species Av.Diss. ± SD Contrib.% Encrusting red algae 2.01 ± 1.94 4.96 Caulacanthus sp. 2.93 ± 1.73 4.99 Cystoseira spp. 1.73 ± 1.38 4.25 E. elongata 2.54 ± 1.34 4.33 C. safiana 1.68 ± 1.34 4.13 Gelidium sp. 2.45 ± 1.37 4.18 Ulva sp. 1.62 ± 1.28 3.98 Ulva sp. 2.43 ± 1.32 4.14 Green fil. algae 1.57 ± 1.28 3.88 Polyplacophora 2.29 ± 1.25 3.90 Dyctiota spp. 1.44 ± 1.19 3.56 Encrusting red algae 2.22 ± 1.25 3.78 E. punctata 1.31 ± 1.02 3.23 P. rustica 2.14 ± 1.15 3.64 P. perforatus 1.27 ± 0.99 3.20 Hildenbrandia sp. 1.91 ± 1.01 3.25 Hildenbrandia sp. 1.23 ± 0.96 3.12 Gastroclonium sp. 1.88 ± 1.08 3.21 C. sinuosa 1.23 ± 0.95 3.04 Trochidae 1.84 ± 0.95 3.13 A. armata 1.23 ± 0.95 3.03 Mytilus sp. 1.84 ± 0.95 3.13 A. calycularis 1.23 ± 0.95 3.02 A. equina 1.82 ± 0.92 3.10 M. neritoides 1.22 ± 0.95 3.01 P. perforatus 1.80 ± 0.93 3.06 Taxa cover in vertical exposed surfaces. Results of methodology ii We found eight taxa that had an average cover (per site) higher than 20% at least at one locality: Caulacanthus sp., Chthamalus stellatus, Cystoseira spp., Ellisolandia elongata, Encrusting red algae, Lithophyllum byssoides, Mytilus galloprovincialis and Ralfsia verrucosa (Fig. 5). There were significant differences in the individual taxa cover between substrates (artificial vs natural). Although these results depended on the locality, there were some constant patterns across the Alboran Sea (see SNK results in Fig 5). Covers of R. verrucosa were significantly higher on the artificial substrates of Motril (Cubes and Seawall), Málaga (Seawall), Benalmádena, M’Diq and Marina Smir (Tetrapods). The covers of C. stellatus were Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 113 Chapter 2 significantly higher on concrete made artificial substrates (cubes of Fuengirola and Motril, seawalls of Almería and Málaga, and tetrapods of M’Diq and Marina Smir), while they were lower on the natural-rock made rip-raps of Aguadulce and Algeciras. On the other hand, canopy algae cover was significantly lower on artificial substrates of some localities. The coralline algae E. elongata had significantly lower covers on Ceuta (Cubes), Almería (Seawall), Málaga (Seawall), M’Diq (Tetrapod) and Marina Smir (Tetrapod). The cover of Cystoseira spp. was also significantly lower on the cubes of Ceuta, the rip-raps of Marina del Este and the Seawall of Málaga. Interestingly, the cover percentage of the protected coralline algae L. byssoides was quite high in the Cubes of Ceuta. Fig. 5: Taxa cover percentages on vertical surfaces of each substrate. Only taxa with a cover higher than 20% on at least one site are represented. Results of the SNK comparisons according to three-way ANOVA are also given. Art: Artificial; Nat: Natural; CEU: Ceuta; FUE: Fuengirola; MOT: Motril; AGD: Aguadulce; ALG: Algeciras; MES: Marina del Este; ALM: Almería, MAL: Málaga, MOT: Motril; BEN: Benalmádena, MDQ: M’diq; SMR: Marina Smir. Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Regional effects of coastal infrastructure 114 According to the taxa cover percentage on vertical faces, a clear segregation between artificial and natural substrates was observed except for rip-raps (see MDS in Fig. 6). In fact, PERMANOVA detected significant differences between substrates at every locality and type of artificial structure, with the exception of Aguadulce and Marina del Este’s rip-raps (Fig. 6, Supplementary Table 8). These lower dissimilarities between rip-raps and the natural hard substrate were also confirmed by SIMPER (Table 4). Rip-raps had the lowest dissimilarities (61.23%) while seawalls had the highest (74.88%). Fig. 6: MDS for the taxa cover percentages on vertical faces. Dashed boxes contain pair-wise results according to PERMANOVA. Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 115 Chapter 2 Table 4: Results of SIMPER analysis comparing the taxa cover percentages on vertical faces between natural and each of the artificial substrates. Cut off for low contributions: 90%. Av.Diss: Average dissimilarity; SD: standard deviation; Contrib.: contribution to dissimilarity. Intertidal vertical faces Groups Natural & Rip-rap Average dissimilarity = 61.23% Groups Natural & Cube Average dissimilarity = 63.52% Species Av.Diss. ± SD Contrib.% Species Av.Diss. ± SD Contrib.% Empty 11.50 ± 1.35 18.79 E. elongata 8.36 ± 1.24 13.16 E. elongata 9.41 ± 1.29 15.38 Empty 8.14 ± 1.32 12.81 R. verrucosa 8.42 ± 1.22 13.75 C. estellatus 8.10 ± 0.98 12.75 Caulacanthus sp. 7.21 ± 1.14 11.77 R. verrucosa 6.49 ± 1.03 10.21 C. estellatus 5.57 ± 0.77 9.09 Caulacanthus sp. 5.64 ± 1.14 8.87 Hildenbrandia sp. 2.29 ± 0.56 3.73 Encrusting red algae 3.36 ± 0.87 5.77 Encrusting red algae 2.19 ± 0.49 3.57 L. byssoides 3.52 ± 0.57 5.54 Ulva sp. 1.85 ± 0.41 3.02 Cystoseira spp. 3.41 ± 0.50 5.37 Dendropoma sp. 1.84 ± 0.27 3.01 Rhodomelaceae 3.38 ± 0.63 5.32 J. rubens 1.35 ± 0.27 2.21 Ulva sp. 3.04 ± 0.55 4.78 Green filamentous 1.28 ± 0.38 2.09 A. armata 1.47 ± 0.45 2.31 Patella spp. 1.13 ± 0.93 1.85 Hildenbrandia sp. 1.32 ± 0.42 2.08 Rhodomelaceae 0.87 ± 0.37 1.42 P. perforatus 1.26 ± 0.27 1.98 Groups Natural & Tetrapod Average dissimilarity = 64.96% Groups Natural & Seawall Average dissimilarity = 74.88% Species Av.Diss. ± SD Contrib.% Species Av.Diss. ± SD Contrib.% E. elongata 15.06 ± 1.72 23.19 C. estellatus 17.91 ± 1.20 23.29 R. verrucosa 12.67 ± 1.17 19.50 E. elongata 14.35 ± 1.51 19.17 C. estellatus 9.77 ± 1.05 15.04 Empty 10.40 ± 1.35 13.89 Empty 6.74 ± 0.95 10.37 R. verrucosa 6.14 ± 0.84 8.20 Caulacanthus sp. 3.50 ± 0.98 5.38 M. galloprovincialis 5.89 ± 0.71 7.87 A. armata 3.40 ± 1.25 5.24 Caulacanthus sp. 5.22 ± 0.93 6.98 P. perna 2.04 ± 0.52 3.14 Rhodomelaceae 2.19 ± 0.32 2.93 M. galloprovincialis 1.87 ± 0.74 2.88 Dendropoma sp. 1.76 ± 0.37 2.36 C. sinuosa 1.69 ± 0.55 2.60 P. perna 1.64 ± 0.44 2.19 P. perforatus 1.27 ± 0.72 1.96 Hildenbrandia sp. 1.41 ± 0.43 1.88 Encrusting red algae 0.90 ± 0.58 1.38 Ulva sp. 1.34 ± 0.50 1.78 Intertidal communities and abiotic variables We also tested how a set of abiotic variables explained, 1) the full taxonomic structure (presence/absence) found all around each substrate and 2) the taxa cover percentage of only the vertical exposed surfaces. The variables used (macroand microroughness, age, crystallinity, Calcium content [Ca], Magnesium content [Mg] and wave exposure [Fetch index]) clearly segregated artificial from natural substrates and also the seawalls from the rest of artificial substrates (see PCA in Fig. 7). We initially included Al, Fe, K, and Si content and Calcination Percentages but after confirming the collinearity with other variables (Draftman’s plot results not shown), we eliminated those variables from subsequent analyses. The age together with Ca and Mg content were the main drivers segregating the substrates along axis 1 (31.3 % of variance explained). Along this axis, many natural substrates are separated from the artificial ones (and some natural ones) due to their older age and/or high Silicon content (i.e. low Mg Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Regional effects of coastal infrastructure 116 and Ca content). Along axis 2 (20.1 % of variance explained), the main driver was macroscale roughness, segregating clearly the seawalls (that lacked any) from the rest of artificial substrates. Differences in the abiotic nature of cubes, rip-raps and tetrapods were not really evident, since they had a high degree of macroscale roughness and age range. The resulting model of abiotic variables for the full taxonomic structure explained 26.09% of the variance (p<0.0001) (Table 5). According to the marginal effects, Ca and crystallinity were not significantly correlated with the taxonomic structure while macroscale roughness was marginally correlated (p<0.1). Microscale roughness, Mg, Fetch and Age were significantly correlated, being the age of the substrates the variable most correlated. In contrast, when pairing the same abiotic data with the cover percentages of taxa developing on the vertical surfaces, the marginal effects showed a significant correlation of all variables (except for Ca that was marginally significant). The resulting model explained 39.49% of the variance. In both cases, the explained variability can be considered low, indicating an influence of other variables (likely environmental variables acting at regional level) not included in the model. In fact, the MDS using factor Latitude (West, Middle West, Middle East, East) clearly sorted the replicates according to their regional position, independently of substrate type (Fig. 8). The PERMANOVA results (Supplementary table 9) showed the significant effect of latitude (Factor Region: Pseudo-F3,71 = 3.25, p < 0.001), differentiating the taxonomic structure of western regions (ALG, CEU, MDQ, SMR) from the middle western (BEN, FUE, MAL) and the eastern ones (MES, MOT, AGD, ALM) (Fig. 8). Fig. 7: Principal Component Analysis of the abiotic variables used (after variable selection to avoid collinearity). Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 117 Chapter 2 Table 5. Permutation test for dbRDA and CCA for all constrained eigenvalues of taxa cover percentages developing on vertical surfaces and full taxonomic structure respectively. The marginal effects of each abiotic variable tested and the proportion of the inertia explained by the models are also provided. .: p<0.1; *: p<0.05; **: p<0.001; ***: p<0.0001. Full taxonomic structure Df % Explained F P Constrained model 7 26.09% 3.228 *** Residual 64 Df Sum of sqs. F p Macro 1 0.1763 1.8866 . Micro 1 0.2235 2.3914 * Magnesium 1 0.2585 2.7658 ** Calcium 1 0.1283 1.3729 n.s. Crystallinity 1 0.1167 1.2482 n.s. Age 1 0.5213 5.5769 *** Fetch 1 0.2325 2.4870 * Residual 64 5.9824 Vertical faces Df % Explained F P Constrained model 7 39.49% 5.9675 *** Residual 64 Df Sum of sqs. F p Macro 1 0.3046 3.8924 ** Micro 1 0.1919 2.4525 * Magnesium 1 0.2557 3.2679 ** Calcium 1 0.1509 1.9281 . Crystallinity 1 0.2336 2.9845 ** Age 1 0.5700 7.2834 *** Fetch 1 0.3246 4.1479 *** Residual 64 5.9824 Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Regional effects of coastal infrastructure 118 Discussion The comparison between natural and artificial substrates usually yields higher biodiversity values for the former ones (Firth et al., 2016b). As we expected, we found concordant results for the natural substrates studied along the Alboran Sea. Within the twenty-five taxa uniquely found on natural substrates, we found different species of algae (9 out of 25) including Jania rubens, Rissoella verruculosa, Padina pavonica, Halopteris spp., Dictyopteris sp. or Sargassum sp.. These species have different growth forms and provide an algal canopy that may be adequate for hosting a broad number of mobile taxa (Navarro-Barranco et al., 2018; Ólafsson, 2016; Saarinen et al., 2018). The stressful intertidal environment can boost the importance of species-specific interactions between sessile taxa and their associated mobile macroand meiofauna (Bulleri et al., 2016; Sedano et al., 2020a; 2020b). Therefore, the lack of different algae and other sessile taxa with a variety of growth forms may be an important Fig. 8: MDS results portraying the differences between samples according to their latitude (factor Region: four levels). The results of PERMANOVA pair-wise tests are also given. Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 119 Chapter 2 factor affecting the diversity of mobile associated communities on artificial substrates. The reduction of phytal taxa on artificial substrates has been previously reported (Ferrario et al., 2016; Sedano et al., 2019) and it has been identified not only as a handicap for the establishment of propagules and larvae (Arenas et al., 2006; Bulleri et al., 2009), but also as a reduction of primary production for supporting higher trophic levels such as fishes (Cheminée et al., 2017; Thiriet et al., 2016). Apart from macroalgae, within the twenty-five taxa exclusively found in natural substrates, we identified species whose living style does not allow them to be emerged or need a shadowy environment. It is the case of the subtidal grazer Thuridilla hopei, the suspension feeder Aglaophenia pluma, or other subtidal benthic taxa such as Cereus pedunculatus, Terebellidae, Actinaria and Clathrina rubra, the latter being well documented to live underneath shallow subtidal boulders (Trowbridge et al., 2018). Logically, we were able to record these taxa only in some intertidal pools and shady overhangs of natural substrates. The presence of intertidal pools provides refuges for intertidal and subtidal species, representing ‘islands’ of different habitat (Underwood and Skilleter, 1996) scattered within the surrounding rocky surfaces, contributing to the diversity and range of ecological functions of intertidal habitats. This has led to the creation of artificial rock-pools on the usually smooth artificial substrates in order to improve their ecological value (Ostalé-Valriberas et al., 2018). Our results have reinforced the importance of macroand microhabitats in boosting the biodiversity, being the seawalls (featureless artificial substrates) the substrates with the lowest number of taxa. In fact, Eriphia verrucosa and Onchidella celtica were exclusively recorded inhabiting the microhabitats (small crevices) of natural substrates (Kent and Hawkins, 2019). However, we found not only differences in the number or composition, but also in the cover (i.e. abundance) of shared taxa. The results of taxa cover on vertical faces demonstrated that some patterns of occurrence can be generalized along a geographical gradient. For example, the algae R. verrucosa was usually higher in artificial substrates while the cover of canopy algae such as E. elongata and Cystoseira spp. was lower in artificial substrates. We also found higher covers of the barnacle C. stellatus on concrete made structures (cubes, seawalls and Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Regional effects of coastal infrastructure 126 conservation biology. Aquat. Conserv. Mar. Freshw. Ecosyst. 28, 1283–1293. https://doi.org/10.1002/aqc.2944 Evans, A.J., Firth, L.B., Hawkins, S.J., Morris, E.S., Goudge, H., Moore, P.J., 2016. Drill-cored rock pools: An effective method of ecological enhancement on artificial structures. Mar. Freshw. 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Nature 413, 841–844. https://doi.org/10.1038/35101595 Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Regional effects of coastal infrastructure 130 CHAPTER 2.2 Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 131 Chapter 2 2.2 Algae canopy and biodiversity loss on Crete’s rip-raps (Greece) Adapted from: Sedano, F., Florido, M., Rallis, I., Espinosa, F., Gerovasileiou, V. (2019). Comparing sessile benthos on shallow artificial versus natural hard substrates in the Eastern Mediterranean Sea. Mediterranean Marine Science, 20(4), 688-702. https://doi.org/10.12681/mms.17897 Abstract Artificial structures cover a considerable part of the Mediterranean coasts. In the Aegean Sea, most studies related to artificial structures have focused in vagile fauna on harbours and marinas but little attention has been given to the sessile biota on coastal defense structures. The aim of this work was to describe for the first time the shallow subtidal sessile benthos on coastal defense structures in Crete (Eastern Mediterranean Sea) in order to identify potential differences in comparison to natural rocky substrates, adopting both a taxonomic and functional (i.e. macroalgal structural complexity) approach. Three shallow (1-3 m) localities were studied in the north coast and three in the south coast of the island (six localities in total). At each locality, two types of hard substrate were selected: an artificial coastal defense structure (riprap) and the nearest natural rocky substrates. The percent cover of sessile taxa was calculated using random points counts over photoquadrats (20 x 20 cm). The structure of the assemblage differed between artificial and natural habitats. Values of Shannon-Wiener’s diversity index and number of taxa were higher in natural substrates. In addition, cover of arborescent macroalgae was lower on artificial substrates. In conclusion, rip-raps do not function as surrogates of natural hard substrates in the study area since their shallow subtidal assemblages differ in terms of community structure, diversity and functionality. The deficient performance of such artificial structures could be attributed to the combined effects of abiotic factors and biotic processes, including substrate nature and roughness as well as differential grazing pressure. Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Regional effects of coastal infrastructure 132 Introduction Shoreline urbanization combined with the increase of tourist, recreational and commercial activities, result in the introduction and proliferation of artificial structures in marine coastal habitats worldwide (Bulleri and Chapman, 2010; Dafforn et al., 2015; Firth et al., 2016a). These structures are mostly linked to coastal defense purposes against sea-level rise, but also to commercial infrastructures, protection against coastal erosion and wave action, extraction of oil (e.g. offshore platforms), energy generation (e.g. wind farms) and aquaculture (Bacchiocchi and Airoldi, 2003; Dafforn et al., 2015; Firth et al., 2016a and references therein). Recently, some eco-engineering interventions have been carried out with the purpose of increasing or maintaining biodiversity inhabiting such structures (see review by Strain et al., 2018). Nevertheless, strict or well-defined ecological criteria and management practices are lacking during the design stage or after installation of these infrastructures (Moschella et al., 2005; Firth et al., 2014, Dafforn et al., 2015). Their impacts have been largely documented, generally concluding that artificial structures do not function per se as surrogates of natural habitats (e.g. Bulleri and Chapman, 2010; Perkins et al., 2015) due to different habitat complexity (e.g. Perkol-Finkel and Benayahu, 2004; Lam et al., 2009; Loke et al., 2015; Mercader et al., 2017), nature of building materials (e.g. Coombes et al., 2015; Sempere-Valverde et al., 2018), surface inclination and orientation (e.g. Moreira et al., 2006; Chapman and Underwood, 2011) and even differential grazing pressure between artificial and natural habitats (Ferrario et al., 2016). Consequently, the importance of ecological characterization of these structures and the incorporation of ecological criteria in their design should not be neglected (Mosquella et al., 2005; Perkins et al., 2015). The European coasts have been highly modified by the introduction of artificial structures (Airoldi and Beck, 2007). In the Mediterranean Sea, the ecological study of artificial structures as “hot spots” of biological invasions has been particularly prolific, focusing mainly in marinas (e.g. Ros et al., 2014; Ulman et al., 2017; Martínez-Laiz et al., 2018) or artificial reefs (Fabi et al., 2011; López et al., 2016). However, only few studies have compared communities of Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 133 Chapter 2 natural hard habitats with coastal defense structures (e.g. Gacia et al., 2007; García-Gómez et al., 2015; Ido and Shimrit, 2015). In the Aegean Sea, most studies related to artificial structures have focused in vagile fauna associated with harbours and marinas (Karalis et al., 2003; Chintiroglou et al., 2004; Corsini-Foka et al., 2015; Ulman et al., 2017; Chatzinikolaou et al., 2018; Zenetos et al., 2018), aquaculture facilities (Fernández-González and Sánchez-Jerez, 2017) and artificial reefs (Sinis et al., 2000; Lök et al., 2008; Klaoudatos et al., 2012). Regarding sessile fauna, a recent study in Saronikos Gulf found higher abundances of the cryptogenic coral Oculina patagonica over anthropogenic structures compared with natural habitats (Salomidi et al., 2013). The northern coast of Crete (Eastern Mediterranean Sea, Greece) is greatly affected by urbanization because the largest cities and main tourist infrastructures (e.g. harbours) of the island are located there (e.g. Chatzinikolaou and Arvanitidis, 2016). This has resulted in an increase of maritime traffic and the establishment of various types of coastal defense structures. In spite of this, there is a lack of studies on the impact of these structures on the benthic biota. The aim of this work was to study and compare for the first time the subtidal sessile benthos on coastal defense structures with that of nearby natural rocky substrates around Crete. Our main hypothesis is that the assemblage structure and function (in terms of macroalgal structural complexity) will differ significantly between artificial and natural substrates. Materials and methods Study area Crete (Greece) is located between the Aegean and Libyan Seas in the Eastern Mediterranean Sea, one of the most oligotrophic marine areas (Boetius et al., 1996) and among the main hotspots for marine bioinvasions worldwide (Rilov and Galil, 2009). Six localities around Crete Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Regional effects of coastal infrastructure 134 (Fig. 1) were studied: three in the north (South Aegean Sea) and three in the south (Libyan Sea) coast of the island. Northern localities were Kato Galatas (35.513º N, 23.964° E), Bali (35.413° N, 24.784° E) and Gournes (35.336° N, 25.299° E), while southern localities were Hora Sfakion (31.198º N, 24.136º E), Agia Galini (35.094º N, 24.689° E) and Tsoutsouros (34.150º N, 25.287º E). At each locality, two types of hard substrates were sampled in the upper subtidal zone (1-3 m deep): (a) artificial boulder-like coastal defense structures (hereafter “rip-raps”) deployed in marinas more than 10 years ago, and (b) nearby natural rock (Habitat type “1170 Reefs” according to the EU Directive 92/43/EEC). Natural substrates within each locality were predominantly adjacent to rip-raps, except for one locality (Gournes) where the only available natural hard substrate was located approximately 1 km away from the rip-raps. The sampled substrates faced North/North-east in the three northern localities and to South in the southern ones. Fig. 1. Sampling localities in Crete Island. 1: Kato Galatas; 2: Bali; 3: Gournes; 4: Hora Sfakion; 5: Agia Galini; 6: Tsoutsouros. Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 135 Chapter 2 Samples collection and processing Sampling took place in July 2017. At each locality, three random sites located tens of meters apart, were selected for each substrate type. Within each site, three quadrats were photographed using an Olympus TG4 camera with a Subacqua Helios 1700 focus light. A total of 108 photoquadrats were collected (3 photoquadrats * 3 sites * 2 substrates * 6 localities). Photoquadrats were randomly taken while snorkeling at a depth of 1-3 m by placing a 20 x 20 cm aluminum square frame (Bianchi et al., 2004). At each site, the first quadrat was placed at the first available subtidal vertical surface orientated seawards. Subsequent quadrats were placed at the first available surface at least 3 m away or further. Cover of sessile species was measured by spawning 100 random points using PhotoQuad software (Trygonis and Sini, 2012). Sessile taxa that were present in the photoquadrats but did not fall below a random point were given an arbitrary value of 0.5% cover (Bacchiocchi and Airoldi, 2003; Marzinelli et al., 2011; Ostalé-Valriberas et al., 2018). Qualitative samples of the main benthic taxa present in the photoquadrats were also collected when needed for accurate taxonomic identification in the laboratory. Statistical analyses Taxa cover percentages were calculated for each photoquadrat, and based on these data, values of three diversity indices were further determined: number of taxa (S), ShannonWiener’s diversity (H’) and Pielou’s evenness (J’). In order to test the null hypothesis of no difference in the aforementioned parameters between substrates and orientations and among localities and sites, multivariate and univariate statistical analyses were applied. Four-factor permutational multivariate analysis of variance (PERMANOVA) was used to examine the effect of substrate type, orientation, locality and small-scale heterogeneity (sites within locations) on the structure of the sessile assemblage (based on taxa cover percentages). Thus, four factors were considered: ‘Substrate’ (Su), a fixed factor with two levels (Natural, Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Regional effects of coastal infrastructure 142 According to the SIMPER, seven species contributed to 81.12% of the similarity for natural substrates while only three species accounted for 81.78% of the similarity in artificial substrates (Fig. 4). Ten taxa found in this study were considered as arborescent macroalgae, i.e. Amphiroa cryptarthrodia, A. rigida, Cystoseira spinosa, Dictyota spp., Ellisolandia elongata, Ganonema farinosum, Halopteris scoparia, Jania adhaerens, Laurencia obtusa and Tricleocarpa fragilis. Coralline macroalgae of the genus Lithophyllum dominated on both artificial and natural substrates (Table 1). Consequently, average cover of non-arborescent algae was higher at every locality compared with arborescent taxa. However, average arborescent macroalgae cover was higher in natural (29.15 % ± 3.58, mean ± SE) than in artificial (12.08 % ± 2.12, mean ± SE) habitats and thus the ratio non-arborescent/arborescent algae was higher on artificial substrates (Fig. 5). ANOVA results confirmed those differences (Table 4). Table 2: Results of PERMANOVA test with Substrate (Su), Orientation (Or), Locality (Lo) and Site (St) factors for the total assemblage structure (taxa cover percentages) based on BrayCurtis dissimilarity index of square-root transformed data. MS: mean square; p: level of significance; df: degrees of freedom; n.s.: not significant; * p<0.05; ** p<0.01. Source of variation df MS Pseudo-F p Su 1 23104 5.5842 * Or 1 9908.9 0.94008 n.s. Lo(Or) 4 10541 10.275 ** Su x Or 1 15281 3.6934 * Su x Lo(Or) 4 4137.4 4.0331 ** St (Su x Lo(Or)) 24 1025.9 1.2002 n.s. Residual 72 854.75 Total 107 PERMDISP (Su) F = 4.42 p = 0.045* (Or) F = 3.03 p = 0.115 Pair-wise tests Levels of factor (Or) Su x Or Natural: North = South Artificial: North = South Levels of factor (Su) North: Natural ≠ Artificial South: Natural ≠ Artificial Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 143 Chapter 2 1 Table 3: Results of the four-factor ANOVA for number of taxa, Shannon-Wiener’s diversity and Pielou’s evenness. MS: mean square; p: level of significance; df: degrees of freedom; n.s.: not significant; * p<0.05; ** p<0.01; *** p<0.001. Number of taxa (S) Shannon-Wiener diversity (H') Pielou’s evenness (J') Source of Variation df MS F p MS F p MS F p Su 1 36.0901 24.28 *** 5.9786 27.25 ** 0.5669 25.77 ** Or 1 0.9997 0.49 n.s. 0.0964 0.15 n.s. 0.0045 0.03 n.s. Lo(Or) 4 2.0266 5.96 ** 0.6289 8.84 *** 0.1625 3.44 * St (Su x Lo(Or)) 24 0.3402 0.72 n.s. 0.0711 1.16 n.s. 0.0437 1.58 n.s. Su x Or 1 0.0318 0.02 n.s. 0.2383 1.09 n.s. 0.1039 4.72 n.s. Su x Lo(Or) 4 1.4864 4.37 ** 0.2193 3.08 * 0.1039 0.47 n.s. Residual 72 0.4705 0.0615 0.0300 TOTAL 107 Cochran's test 0.4085 0.0998 0.1281 p<0.01 n.s. n.s. Transformation Box-Cox (λ=0.3555) Box-Cox (λ=0.2548) Box-Cox (λ=0.2021) Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Regional effects of coastal infrastructure 144 Table 4: ANOVA test with Substrate (Su) and Orientation (Or) factors for arborescent algae cover percentages. Due to heteroscedasticity, level of significance was reduced to p<0.01 to reduce type I error. MS: mean square; p: level of significance; df: degrees of freedom; n.s.: not significant; * p<0.01. Source of variation df MS Pseudo-F p Su 1 7862.6134 19.098 * Or 1 368.5208 0.522 n.s. Su x Or 1 1629.4468 3.56 n.s. Residual 104 458.0262 Total 107 Cochran-test p<0.01 Fig. 4. Results of SIMPER analysis. Taxa that contributed less than 5% to the total similarity are not shown. Histograms represent contributions (bars, left axis) and cumulative contributions (grey line, right axis) for the taxa indicated with natural numbers (Group Natural) or Roman numerals (Group Artificial). Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 145 Chapter 2 Discussion Shallow subtidal hard bottoms have been scarcely investigated in Crete, apart from some studies focusing on qualitative bionomic descriptions (Pérès and Picard, 1958), specific taxa (Poursanidis et al., 2016; Katsanevakis et al., 2017) or macrofaunal vagile assemblages (Chatzigeorgiou et al., 2012; Poursanidis et al., 2019). This work constitutes, therefore, the first quantitative comparative description of the shallow subtidal sessile benthos between artificial (rip-raps) and natural hard substrates in the area. The results supported our initial hypothesis and showed that rip-raps do not function as surrogates of natural hard substrates in the area since (1) the sessile assemblage was significantly different to that on natural rocky bottoms, (2) rip-raps supported fewer taxa and (3) had a significantly lower cover of habitatforming arborescent macroalgae. In shallow subtidal rocky bottoms, where light is not a limiting factor, macroalgae are expected to form a major component of sessile benthos, playing such important roles as nutrient cycling and ecosystem engineering, thus providing habitat for a broad range of organisms (e.g. Crooks, 2002; Ólafsson, 2017). Our study showed that macroalgae, and particularly rhodophytes, were the dominant taxa in natural substrates; on the contrary, macroalgae diversity was much lower on rip-raps. Indeed, rhodophytes have been previously reported as the dominant macroalgal taxon in shallow waters of Greece (Lazaridou et al., 1997). The Fig. 5. Average cover (%) of arborescent and nonarborescent algae on artificial and natural substrates. The ratio non-arborescent/arborescent is also shown. Error bars represent standard deviation (SD). Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Regional effects of coastal infrastructure 146 species composition of the studied natural hard substrates was similar to that described from moderately exposed subtidal hard substrates in the Aegean Sea (Orfanidis et al., 2005) and light-demanding hard bottoms in the Mediterranean Sea (e.g. Boudouresque, 1971; Ballesteros, 1993). Artificial substrates are often subjected to important levels of disturbance (Airoldi and Bulleri, 2011). These artificial habitats are usually characterized by low biodiversity (Odum, 1985), where usually a few opportunistic species thrive (Orfanidis et al., 2003; Dafforn et al., 2009). This is the case of Cladophora spp., which show tolerance to environmental disturbances (e.g. Peckol and Rivers, 1995; Orfanidis et al., 2001; Salomidi et al., 2016), and presented higher cover percentages on the studied rip-raps compared to natural substrates. In fact, opportunistic species could outcompete other species on hard substrates, thus resulting in fewer number of species than in natural habitats (Bacchiocchi and Airoldi, 2003). It is noteworthy that 17 taxa were exclusively found on natural hard substrates while only three were found as exclusive on artificial ones (Table 1), including the cryptogenic species Ganonema farinosum (Verlaque et al., 2015; Zenetos et al., 2018) that was recently reported to be widely distributed in Crete Island (Gerovasileiou et al., 2017). Moreover, some species found exclusively on natural hard substrates in the study area (e.g. Thylacodes arenarius and Cystoseira spinosa) have been proposed as bioindicators of good environmental status within monitoring schemes under the Marine Strategy Framework Directive (MSFD) (WoRMS Editorial Board, 2018). They are also considered in some ecological indices, such as CARLIT (Ballesteros et al., 2007). In addition, C. spinosa is included in the list of endangered or threatened species (Annex II) of the Barcelona Convention (1996). The sessile benthic assemblage on rip-raps had fewer taxa and lower values of diversity (H’), suggesting that those support a poorer and more homogeneous assemblage than natural rocky reefs. The construction of coastal defense infrastructures (e.g. rip-raps and seawalls) has been previously identified as a “driver of global biotic homogenization” (see review in Firth et al., 2016a) which is defined as the process under which communities become more uniform in terms of number of taxa, similarity of functions and genetic diversity (McKinney, 2006). Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 147 Chapter 2 Differences in assemblage structure between natural and artificial substrates were clearly portrayed by the MDS ordination. In fact, natural substrates were pooled together and separated from artificial ones indicating that the substrate type has a major role in structuring sessile benthos. Multivariate analyses (Supplementary Table 10) highlighted higher variability among localities than among sites within a given locality, indicating that local populations could have been established depending on the local variability of environmental conditions (e.g. Tofts and Silvertown, 2000). Although variability is usually larger at small spatial scales in shallow rocky coasts (Fraschetti et al., 2005), our results suggest higher variability at a broader scale (among different localities, tens of kilometers away); this contrasts with other studies for Mediterranean rocky beds with canopy-forming macroalgae (Dal Bello et al., 2016). Our results might be explained because depth, wave exposure, age and inclination of hard substrates was similar in all sites within localities in an effort to ensure comparability. Nevertheless, statistically significant differences were still found between artificial and natural substrates. Differences of artificial versus natural hard substrate assemblages are mainly related to habitat complexity, wave exposure, age of the substratum, dispersal potential of propagules and larvae, substrate inclination and orientation (e.g. Glasby and Connell, 2001; Firth et al., 2016b; Ushiama et al., 2016), herbivory (Forrest et al., 2013; Ferrario et al., 2016), roughness and nature of building materials (e.g. Coombes et al., 2015; Cacabelos et al., 2016; SempereValverde et al., 2018). The sampling design considered in our study eliminated potential confounding effects due to some factors (e.g. wave exposure, inclination and dispersal of propagules and larvae), thus allowing more rigorous conclusions with regard to the examined factors. So far, it is uncertain how many years are needed for artificial structures to hold a “climax community” or to determine if that is even possible. Some authors have estimated that it takes between 5 and 20 years for artificial structures to reach climax communities (Hawkins et al., 1983; Pinn et al., 2005; Coombes, 2011) while others suggest that low crested structures (like the ones studied here) never become natural climax communities (Gacia et al., 2007) or that incomplete succession could be a persistent stable state (Ferrario et al., 2016 and references Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Regional effects of coastal infrastructure 148 therein). The taxa which were exclusively found on natural substrates in the study area reproduce by releasing spores or larvae to the water column, being capable of colonising nearby hard substrates within the immersion time of the studied artificial substrates (>10 years). Thus, we believe that the immersion time of the artificial substrates was not a major factor structuring the communities in the present study. Different substrate inclination (i.e. vertical versus horizontal surfaces) has been shown to affect small-scale variability on artificial substrates (Glasby, 2000; Ushiama et al., 2016). In this study, all examined surfaces were vertical in order to minimize heterogeneity linked to different surface inclination. Exposure to sunlight has been found to have more determinant effects on epibiotic assemblages compared to surface inclination (see Glasby and Connell, 2001). Nevertheless, in our study there were no significant differences between northern and southern localities. In addition, the entire coastline of Crete belongs to the same biogeographical area (the South Aegean ecoregion) and there is high connectivity between the north and south sides due to the interconnection of cyclonic and anticyclonic gyres by currents and jets (Theocharis et al., 1999). All in all, and given that the sampled artificial structures in our study were adjacent to natural hard substrates, thus facilitating the potential nourishment of rip-raps (Gacia et al., 2007), it is improbable that poor larval or propagules dispersal limits the establishment of assemblages on rip-raps. On the other hand, their settlement could be affected by other factors such as nature of building materials and roughness (Coombes et al., 2015; Ido and Shimrit, 2015; Sempere-Valverde et al., 2018) or ecological processes, such as grazing, predation and competition (Foster et al., 2003; Bulleri, 2005; Marzinelli et al., 2011; Ferrario et al., 2017). Besides the differences in assemblage composition and diversity, the cover of habitatforming arborescent macroalgae was significantly lower in rip-raps, thus potentially generating differences in ecosystem functioning. These species can modify the community structure (Benedetti-Cecchi et al., 2001; Maggi et al., 2009) by providing new habitat and shelter (Boudouresque, 1971; Cheminée et al., 2017) and facilitating the establishment of propagules and larvae (Arenas et al., 2006; Bulleri, et al., 2009). In addition to the increase of habitat Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 149 Chapter 2 complexity, they constitute an important source of primary production, supporting rich vagile biota, such as fish (Thiriet et al., 2016; Cheminée et al., 2017). In natural habitats, coexistence of arborescent and encrusting taxa on macroalgal communities is common since encrusting species are usually tolerant to overgrowth (Airoldi, 2000; Bulleri, 2006); this coexistence was observed in the studied natural substrates while ripraps exhibited a shift towards non-arborescent algae. This might be explained by different grazing pressures between habitats. Indeed, grazing has been identified as relevant in shaping macroalgal assemblages (Underwood and Jernakoff, 1984; Coleman et al., 2006; Tsirintanis et al., 2018). For instance, Ferrario et al. (2016) reported higher grazing pressure in artificial structures in comparison to natural ones in the North Adriatic Sea. First, isolated artificial structures over soft bottoms would probably be subjected to higher grazing pressure compared to large rocky reefs due to the greater concentration of potential grazers in the only available, artificial rocky substrates (Ferrario et al., 2016). In our case, Gournes had rip-raps settled over soft bottoms approximately 1 km away from the nearest natural rocky shore. Second, the higher diversity and abundance of palatable algae in natural habitats results in a share-out of grazing pressure among targeted algae species. In accordance with this hypothesis, the most abundant arborescent species of the study area (Jania adhaerens, Laurencia obtusa and Amphiroa rigida) were absent from rip-raps. However, apart from Gournes, rip-raps in other localities were adjacent to natural hard substrates. Therefore, a different grazing pressure across localities from highly motile herbivores such as certain fishes is rather unlikely. Nevertheless, the invasive crab Percnon gibbesi (H. Milne Edwards, 1853) was abundant in all sampling localities in the boulder-like rip-raps (authors’ personal observations, Fig. 6). Percnon gibbesi has been described as a herbivorous species, mostly feeding on articulated Corallinaceae and Sphacelariaceae (Deudero et al., 2005; Puccio et al., 2006), possibly exerting this way a differential grazing pressure. Katsanevakis et al. (2010) also measured higher densities of this crab in boulder-like habitats near marinas. Therefore, it is likely that the introduction of highly heterogeneous artificial structures for coastal defense purposes could facilitate the establishment of some non-indigenous species. The potential impact of such introductions Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b Regional effects of coastal infrastructure 150 should be considered in future management practices for deployment of coastal defense structures, especially in marine areas highly susceptible to biological invasions. Conclusions In conclusion, the composition and diversity of shallow subtidal sessile assemblages on ripraps suggest that these artificial structures do not function as surrogates of natural hard substrates in the study area, considering both a taxonomic and a functional approach. The deficient performance of this artificial habitat could be attributed to a combination of cooccurring abiotic and biotic factors such as the nature and roughness of the building material as well as differential grazing pressure. We suggest that future constructions should apply Fig. 6. Specimens of the invasive crab Percnon gibbesi (encircled) inhabiting a boulder-like rip-rap in one the sampling locations (July 2017, Kato Galatas, Crete). Código seguro de Verificación : GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b | Puede verificar la integridad de este documento en la siguiente dirección : https://sede.administracionespublicas.gob.es/valida ÁMBITOPREFIJO CSV FECHA Y HORA DEL DOCUMENTO GEISER GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 29/09/2020 19:38:30 Horario peninsular Nº registro DIRECCIÓN DE VALIDACIÓN O00008744e2000046037 https://sede.administracionespublicas.gob.es/valida GEISER-3b66-3d1e-1b5c-48dd-914f-573f-c6ba-5f6b 151 Chapter 2 ecological criteria considering various materials (e.g. Sempere-Valverde et al., 2018) and novel designs (Ostalé-Valriberas et al., 2018) which could match the particular scenario of the Cretan coast. Further research for the ecological characterization of these structures is critical in order to improve our knowledge in support of better management practices, under the framework of green engineering, in coastal and marine infrastructure of the Eastern Mediterranean Sea. Acknowledgements We would like to thank Konstantinos Tsiamis and Carlos María López for helping with algae and bryozoan identification respectively, Giorgos Chatzigeorgiou, Christos Arvanitidis, Carlos Navarro and José Manuel Guerra for their help with statistical analyses. Our gratitude to Thanos Dailianis, Wanda Plaitis, Lucia Fanini and Costas Dounas for their support during the ERASMUS/summer internship of the first three authors. We are also grateful to the two anonymous reviewers for their constructive comments that greatly improved the first version of the manuscript. References Airoldi, L., 2000. Effects of disturbance, life histories, and overgrowth on coexistence of algal crusts and turfs. Ecology, 81 (3), 798-814. Airoldi, L., Beck, M.W., 2007. Loss, status and trends for coastal marine habitats of Europe. Oceanogr. Mar. Bio. An Ann. Rev., 45, 345-405. Airoldi, L., Bulleri, F., 2011. 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