Freshwater fish that are acutely exposed to copper (Cu) can experience disturbances of ion regulation and ammonia excretion. Temperature has been shown to affect Cu bioaccumulation and toxicity in fish, but the focus has largely been on warm temperature effects. Yet, acclimation of freshwater fish to near-freezing temperatures encountered during the winter of temperate regions can challenge fish condition and physiology, including ion regulation. Thus, temperate freshwater fish might be particularly sensitive to Cu in the winter. We investigated how winter cold affects acute Cu bioaccumulation and toxicity in juvenile brook char (). Following gradual acclimation to cold temperature (-2 °C/week from 14 °C, then 4 weeks at 3 °C) vs. a warmer temperature around the species thermal optimum (14 °C for 9 weeks), and following a cold challenge (-3 °C/day from 14 °C, then 24 h at 3 °C) vs. a cold acclimation (-2 °C/week from 14 °C, then 13 weeks at 3 °C), we measured gill-Cu bioaccumulation, net fluxes of ammonia (NH), chloride (Cl) and net and unidirectional fluxes of sodium (Na) over a 30-h Cu exposure. Overall, winter cold did not appear to be challenging to brook char, as cold-acclimated fish had a higher fish condition and showed no sign of ion regulation impairment or increased Cu sensitivity. Contrary to our prediction, we found that Cu bioaccumulation over a 30-h Cu exposure was not significantly affected by acclimation temperature. Effects of temperature on Cu physiological effects were relatively limited (mainly on inhibition of Na influx and of NH excretion), with slightly greater effects observed in 14 °C-acclimated fish.

中文翻译：

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冬季寒冷对红点鲑（Salvelinus fontinalis）急性铜生物累积和毒性的影响


严重接触铜 (Cu) 的淡水鱼可能会出现离子调节和氨排泄紊乱。温度已被证明会影响鱼类体内铜的生物累积和毒性，但重点主要集中在温暖的温度影响上。然而，淡水鱼对温带地区冬季接近冰点温度的适应可能会挑战鱼类的状况和生理机能，包括离子调节。因此，温带淡水鱼在冬季可能对铜特别敏感。我们研究了冬季寒冷如何影响幼溪炭的急性铜生物积累和毒性（）。逐渐适应寒冷温度（从 14 °C 开始-2 °C/周，然后在 3 °C 下 4 周）与物种热最适温度附近的较温暖温度（14 °C 持续 9 周）以及寒冷挑战之后（从 14°C 开始-3°C/天，然后在 3°C 下 24 小时）与冷驯化（从 14°C 开始-2°C/周，然后在 3°C 下 13 周），我们测量了鳃-铜暴露 30 小时内的铜生物累积、氨 (NH)、氯化物 (Cl) 的净通量以及钠 (Na) 的净和单向通量。总体而言，冬季寒冷似乎对溪炭没有挑战性，因为适应寒冷的鱼具有较高的鱼体状况，并且没有显示出离子调节受损或铜敏感性增加的迹象。与我们的预测相反，我们发现铜暴露 30 小时后的铜生物富集并没有受到驯化温度的显着影响。温度对 Cu 生理效应的影响相对有限（主要是抑制 Na 流入和 NH 排泄），在 14 °C 驯化的鱼中观察到的影响稍大。