Cortisol and glucose responses in juvenile brown trout subjected to a fluctuating flow regime in an artificial stream |
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Authors: | L E W Flodmark H A Urke J H Halleraker J V Arnekleiv L A Vøllestad A B S Poléo |
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Institution: | University of Oslo, Department of Biology, P.O. Box 1050 Blindern, N-0316 Oslo, Norway;Norwegian University of Technology and Science, Museum of Natural History and Archaeology, N-7491 Trondheim, Norway;Directorate for Nature Management, N-7485 Trondheim, Norway |
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Abstract: | In an artificial stream channel, wild 1 year old brown trout Salmo trutta were exposed to fluctuations in flow and water level to simulate hydro-peaking conditions downstream of a hydropower installation. Blood plasma cortisol concentrations reached a maximum of 59·4 ± 35·3 ng ml−1 (mean ± 95% CL) 2h after the end of down-ramping. Return to the pre-exposure cortisol level was achieved within 6 h. When subjected to daily cyclical fluctuations over 7 days, plasma cortisol levels were significantly elevated (61·3 ± 26·8 ng ml−1) on the first day compared to undisturbed fish (4·9 ± 3·7 ng ml−1). On the fourth and seventh day, no elevation in plasma cortisol above control levels was observed. No changes in blood glucose that could be attributed to the stressor were found. There was no correlation between plasma cortisol and blood glucose levels. The short-lived cortisol response to daily fluctuations indicates a rapid habituation to this Stressor. |
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Keywords: | hydropower parr Salmo trutta stress water level |
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