The impact of elevated water nitrate concentration on physiology,growth and feed intake of African catfish Clarias gariepinus (Burchell 1822) |
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| Authors: | Wout Abbink Yanick Yokohama Tom Spanings Pepijn de Vries Stijn Bierman Hans van de Vis Gert Flik |
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| Institution: | 1. IMARES, Wageningen Aquaculture, Wageningen UR, , IJmuiden, The Netherlands;2. Department of Animal Physiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University Nijmegen, , Nijmegen, The Netherlands |
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| Abstract: | The nitrate threshold concentration in rearing water of African catfish (Clarias gariepinus) was assessed. Female African catfish with an initial mean (SD) weight of 154.3 (7.5) g were exposed to 0.4 (Control), 1.5, 4.2, 9.7 and 27.0 mM nitrate for 42 days. Mean (SD) plasma concentrations of nitrate increased from 71 (29) to 6623 (921) μM at the highest ambient nitrate level. Mean (SD) plasma nitrite concentration ranged from 1.2 (0.5) to 7.9 (9.0) μM. Haematocrit, plasma concentrations of non‐esterified fatty acids (NEFA), cortisol, glucose, lactate, osmolality, gill morphology and branchial Na+/K+‐ATPase activity were not affected. Feed intake and specific growth rate were significantly reduced at the highest nitrate concentration. We advise not to exceed a water nitrate concentration of 10 mM (140 mg L?1 NO3‐N) to prevent the risk of reduced growth and feed intake in African catfish aquaculture. |
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| Keywords: | African catfish nitrate toxicity specific growth rate feed intake stress physiology recirculating aquaculture systems |
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