Exploring a first-principles based model of zooplankton respiration

Explo ing a i s -p inciples based model o zooplank on espi a ion T.T. Packa d*†§, M. Gómez§ and M. Alca az*. *Ins i u o de Ciencias del Ma , Paseo Ma í imo de la Ba celone a 37-49, 08003 Ba celona, Spain †Bigelow Labo a o y o Ocean Science, W. Boo hbay Ha bo , Maine 04575, USA §Biological Oceanog aphy Labo a o y, Facul ad de Ciencias del Ma , Uni e sidad de Las Palmas de G an Cana ia, Campus Uni e si a io de Ta i a., 35017 Las Palmas de G.C., Cana y Islands, Spain. This is a con ibu ion om ICM-CSIC, BLOS, ULPGC, he p ojec s: MICROROL (CICYT CTM2004-02757/MAR), MODIVUS (CTM2005- 04795/MAR), OITHONA (CTM2007-60052). Bu he MTE only p edic s espi a ion when he ood supply is adequa e! Senescence espi a ion can’ be p edic ed (Fig. 3)! Compa ing Figs. 1 and 3 shows ha clea ly. How can you model p edic espi a ion when ood is sca ce and espi a ion alls? No e pa allelism in Fig. 3 be ween dec eases in espi a ion and py u a e ( ood sou ce) du ing hou 10 o 13. Some hing in he ood limi s espi a ion. Tha ’s ou hypo hesis! Since enzymes con ol espi a ion, ha “some hing” is he enzyme’s subs a es (Fig.4). Consequen ly, we a gue ha a espi a ion model should inco po a e a Michaelis-Men en exp ession (Fig.5). Figs. 1 & 2. Modeling espi a ion om bisubs a e enzyme kine ics is easible in Bac e ia (1). Fo zooplank on, should we adap his model o he MTE model? How does he MTE (Me abolic Theo y o Ecology 2) do his? The MTE would p edic espi a ion (R) by he ollowing equa ion, R = i M0.75, whe e i is a s oichiome ic ac o and M is he biomass (Fig 3). Slide 1 Ou model is: R0 = SVmax0/(Km + S), whe e Vmax0 is, he po en ial espi a ion (ETS). We use  a he han M0.75 because biomass jus packages he ETS. The ETS is he eal cause o espi a ion. Fu he mo e, he ela ionship be ween R and ETS is be e and mo e di ec han be ween R and M (Figs 6, & 7) . 0 25 50 010 20 30 Time (h) Measu ed Modelled PnPy260593 Respi a ion (mM O2 min-1) a Fig. 1 0 10 20 30 010 20 30 Time (h) Respi a ion (mM CO2 min1) PnPy100693 Measu ed Modeled Fig. 2 0 10 20 30 40 50 60 70 0 5 10 15 20 25 30 Time (h) P o ein/5 (mg/L), Py u a e x 3 (mM), R-measu ed & R- p edic ed (mM O2/min) Measu ed Respi a ion Cell P o ein MTE P edic ed Respi a ion Nu ien (py u a e) PnPy260593 Fig. 3 0 10 20 30 40 50 0 5 10 15 20 25 30 Time (h)  NADPH NADH b Fig. 4 0 30 60 010 20 30 TIME (h) M O2 min-1  Measu ed Respi a ion Enzyme Kine ic Model P edic ed Respi a ion Fig 8 y = 0.4656x - 1.5603 R2 = 0.9846 0 50 100 150 200 0 100 200 300 400 Respi a ion (ml O2 h-1animal-  (ml O2 h-1 animal-1) Fig 7 y = 0.9414x - 0.3444 R2 = 0.9811 -3 -2 -1 0 1 2 3 -2 -1 0 1 2 3 Log () Log (Respi a ion) -3 -2 -1 0 1 2 3 -3 -2 -1 0123 Log (D y Weigh ) Log (Respi a ion) y = 0.7565x + 0.1757 R2 = 0.9363 R = 1,5M0,76 Fig 6 This model ans o ms  (Time) in o R = (Time) (Fig 8).