Invasion Ecology of Freshwater Fishes: Insights from Morshi Taluka, Maharashtra

Journal of Research and Development Peer Reviewed International, Open Access Journal. ISSN : 2230-9578 | Website: https://jrdrvb.org Volume-17, Issue-9(II) | September - 2025 68 Invasion Ecology of Freshwater Fishes: Insights from Morshi Taluka, Maharashtra Vinayak Vishwanathrao Tathod1, Prof. Dr. Deeplaxmi Satish Kulkarni2 1Research Center: Bharatiya Mahavidyalaya, Amravati 2Head, Department of Zoology, Bharatiya Mahavidyalaya, Amravati Email: [email protected] Manuscript ID: JRD -2025(I)-170911 ISSN: 2230-9578 Volume 17 Issue 9(II)| Pp. 68-70 Sept. 2025 Submitted: 10 Aug. 2025 Revised: 22 Aug. 2025 Accepted: 20 Sept. 2025 Published: 30 Sept. 2025 Abstract Freshwater ecosystems are biodiversity hotspots that provide essential ecological services but are increasingly threatened by invasive alien species (IAS). This paper examines the invasion ecology of freshwater fishes in Morshi Taluka, Amravati District, Maharashtra, India, with a focus on ecological alterations caused by Oreochromis mossambicus (Mozambique tilapia) and Clarias gariepinus (African catfish). Field surveys across 12 sites (reservoirs, lakes, and rivers) documented shifts in fish community structure, abundance, and diversity indices. Results revealed a sharp decline in native fish richness and evenness at sites heavily invaded by tilapia and catfish. Shannon diversity index was significantly lower in invaded habitats (H’ = 1.85) compared to relatively undisturbed ones (H’ = 2.73). Invasive species biomass accounted for up to 60% of fish yield in certain reservoirs. Ecological consequences included reduced recruitment of native carps, altered trophic interactions, and potential long-term risks to ecosystem services and fisheries-based livelihoods. This study underscores the need for policy-driven ecological monitoring, invasive control strategies, and community awareness to safeguard India’s freshwater biodiversity. Keywords: invasive species, freshwater biodiversity, fish ecology, ecosystem alterations, Morshi Taluka, ecological management Introduction Freshwater ecosystems—rivers, lakes, wetlands, and reservoirs—cover less than 1% of Earth’s surface but sustain nearly 10% of all described species (Dudgeon et al., 2006). They provide critical ecological services such as nutrient cycling, carbon sequestration, water purification, and food security for millions of people. Despite their importance, freshwater habitats are among the most threatened globally, facing challenges from pollution, hydrological alteration, overexploitation, and, increasingly, biological invasions (Strayer, 2010).Invasive alien species (IAS) are organisms introduced beyond their native ranges that establish, spread, and cause ecological or socio-economic harm (IUCN, 2000). In aquatic systems, invasive fishes have become drivers of biodiversity decline, second only to habitat loss. They compete for food and habitat, predate on indigenous fauna, alter nutrient cycles, and disrupt ecological balance (Canonico et al., 2005). India, home to nearly 1000 freshwater fish species, is no exception. The country has witnessed rapid introductions of exotic fishes for aquaculture (e.g., Oreochromis, Cyprinus), ornamental trade, and accidental escapes. Many of these introductions have become invasive, threatening endemic fishes and aquatic food webs (Singh & Lakra, 2011).Morshi Taluka in Amravati District, located in the upper Wardha River basin of central India, supports a network of reservoirs, rivers, and village lakes. Traditional capture fisheries and small-scale aquaculture play important roles in local livelihoods. However, reports of declining catches of native carps and predatory fishes have coincided with the spread of invasive tilapia (O. mossambicus) and African catfish (C. gariepinus). Quick Response Code: Website: https://jrdrvb.org/ DOI: Creative Commons (CC BY-NC-SA 4.0) This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International Public License, which allows others to remix, tweak, and build upon the work noncommercially, as long as appropriate credit is given and the new creations ae licensed under the idential terms. Address for correspondence: Vinayak Vishwanathrao Tathod , Research Center: Bharatiya Mahavidyalaya, Amravati How to cite this article: Vinayak Vishwanathrao Tathod, Deeplaxmi Satish Kulkarni, (2025). Invasion Ecology of Freshwater Fishes: Insights from Morshi Taluka, Maharashtra Journal of Research & Development, 17(9(II)), 68-70. Original Article Journal of Research and Development Peer Reviewed International, Open Access Journal. ISSN : 2230-9578 | Website: https://jrdrvb.org Volume-17, Issue-9(II) | September - 2025 69 Both species exhibit traits such as rapid growth, high fecundity, environmental tolerance, and aggressive behavior, enabling them to dominate invaded ecosystems (Lowe et al., 2000). Objectives of the study 1. To document fish species composition in freshwater bodies of Morshi Taluka. 2. To evaluate the ecological impact of invasive fishes on native biodiversity. 3. To analyze shifts in community structure using diversity indices. 4. To recommend conservation and management strategies for sustainable fisheries. 2. Materials and Methods 1 Study Area Morshi Taluka lies in the north-eastern Amravati District, Maharashtra, covering ~900 km² within the upper Wardha basin. The region experiences a tropical monsoon climate, with seasonal rainfall (800–1000 mm annually) influencing fish breeding cycles. Study sites included:  5 reservoirs (Ambada, Mozari, Loni, Kholapur, and Rahatgaon)  4 lakes (Triveni, Chandur, Kurha, and Hatgaon)  3 river stretches of the Wardha River These water bodies support artisanal fishing, irrigation, and domestic use. 2 Sampling and Data Collection Surveys were carried out between January 2024 and July 2025, covering pre-monsoon, monsoon, and post-monsoon seasons. Standardized gear was used:  Gill nets (20–80 mm mesh) for medium–large fishes  Cast nets for smaller shoaling species  Traps and hand nets for benthic and nocturnal species Fish were identified using taxonomic keys (Froese & Pauly, 2023). Each species was classified as native or invasive. Abundance, biomass, and frequency of occurrence were recorded. 3 Data Analysis Ecological indices were calculated for each site:  Species Richness (S) – number of species  Shannon-Wiener Index (H’) – species diversity  Simpson’s Dominance Index (D) – dominance of a few species  Pielou’s Evenness (J’) – distribution uniformity Statistical tests (ANOVA, t-test) were applied using SPSS v26, with significance at p < 0.05. 3. Results 1 Fish Species Composition Across 12 sites, 32 fish species were recorded, including 26 natives and 6 invasives.  Native species (examples): Catla catla, Labeo rohita, Cirrhinus mrigala, Channa punctata, Mystus vittatus, Ompok bimaculatus  Invasive species (key): Oreochromis mossambicus, Clarias gariepinus, Cyprinus carpio, Hypophthalmichthys molitrix 2 Impact of Invasive Species  Tilapia-dominated sites showed 40–50% decline in native herbivores and omnivores.  African catfish predation caused ~35% reduction in carp juveniles.  Invasive biomass made up to 60% of fish yield in Mozari and Ambada reservoirs.  Native carnivores (Channa marulius, Wallago attu) were displaced in invaded sites. 3 Diversity Indices Site Total Species Native Invasi ve Dominant Invasive Shannon Index (H’) Simpson’s D Ambada servoir 15 9 6 O. mossambicus 1.85 0.42 WardhaRiver (stretch 1) 18 14 4 C. gariepinus 2.3 0.25 Triveni Lake 12 7 5 O. mossambicus 1.65 0.48 Mozari eservoir 10 6 4 C. gariepinus 1.55 0.51 Journal of Research and Development Peer Reviewed International, Open Access Journal. ISSN : 2230-9578 | Website: https://jrdrvb.org Volume-17, Issue-9(II) | September - 2025 70 Key trends:  Mean Shannon index significantly lower in invaded sites (1.85) vs undisturbed (2.73).  Simpson’s dominance higher in invaded sites (0.42) vs non-invaded (0.21).  Evenness index (J’) reflected skewed dominance in invaded reservoirs. Discussion This study demonstrates that invasive fishes have reshaped freshwater communities in Morshi Taluka. The dominance of tilapia and catfish mirrors global trends where invasives disrupt ecological balance (Canonico et al., 2005). 1 Mechanisms of Invasiveness  High fecundity – multiple breeding cycles annually.  Environmental tolerance – survival under low oxygen, fluctuating pH.  Predatory pressure – African catfish consume fish eggs, juveniles, and even amphibians.  Competition – Tilapia monopolizes planktonic and benthic food resources. 2 Ecological Consequences 1. Decline of native carps reduces biodiversity and impacts nutrient cycling. 2. Altered food webs may increase algal blooms, as herbivorous natives decline. 3. Loss of ecosystem services – purification, regulation, and productivity are compromised. 4. Local fisheries at risk – fishers report declining catches of market-preferred natives. 3 Socio-economic Implications  Reduced income for artisanal fishers.  Market shift towards invasive fish, though less preferred by consumers.  Potential food security issues if native stocks collapse. 4 Management Recommendations  Regulation: Ban intentional introduction of C. gariepinus and restrict tilapia farming.  Restoration: Promote native species restocking (carps, snakeheads).  Community awareness: Involve local fishers in biodiversity conservation.  Monitoring programs: Long-term ecological surveillance with local universities. Conclusion The invasion of O. mossambicus and C. gariepinus has significantly altered freshwater ecosystems of Morshi Taluka. Key outcomes include:  Decline in native richness and evenness.  Biomass dominance by invasives.  Altered trophic interactions and fisheries decline. Urgent action is required, integrating policy, science, and community participation, to safeguard freshwater biodiversity and sustain livelihoods. Acknowledgements We acknowledge the support of local fishing communities of Morshi Taluka, laboratory facilities at Bharatiya Mahavidyalaya, Amravati, and Sant Gadge Baba Amravati University. References 1. Canonico, G. C., et al. (2005). The effects of introduced tilapias on native biodiversity. Aquatic Conservation: Marine and Freshwater Ecosystems, 15, 463–483. 2. Dudgeon, D., et al. (2006). Freshwater biodiversity: Importance, threats, status and conservation challenges. Biological Reviews, 81(2), 163–182. 3. Froese, R., & Pauly, D. (Eds.). (2023). FishBase. www.fishbase.org 4. Lowe, S., Browne, M., Boudjelas, S., & De Poorter, M. (2000). 100 of the World’s Worst Invasive Alien Species. IUCN/SSC Invasive Species Specialist Group. 5. Singh, A. K., & Lakra, W. S. (2011). Risk and benefit assessment of alien fish species of the aquaculture and aquarium trade into India. Reviews in Aquaculture, 3(1), 3–18. 6. Strayer, D. L. (2010). Alien species in fresh waters: Ecological effects, interactions with other stressors, and prospects for the future. Freshwater Biology, 55, 152–174. 7. Central Pollution Control Board. (2019). Status of Freshwater Ecosystems in India. MoEFCC, Government of India.