Institute of Life, Earth and Environment (ILEE), Research Unit in Environmental and Evolutionary Biology (URBE), University of Namur, Rue de Bruxelles, 61, B-5000, Namur, Belgium.
Veterinary and Agrochemical Research Center, Groeselenberg 99, 1180, Uccle, Belgium.
Fish Physiol Biochem. 2019 Aug;45(4):1245-1260. doi: 10.1007/s10695-019-00666-x. Epub 2019 Jun 12.
Anthropogenic use of water systems may cause temperature fluctuations between tributaries and large rivers for which physiological population related-effects on osmoregulatory capacity of Atlantic salmon are not well described. We simulated the downstream route in the case of the River Meuse basin to investigate the impact of a 5 °C temperature shift during smoltification on hypo-osmoregulatory capacities of smolts. Three temperature regimes were tested: control temperature-treatment (T1) without temperature shift, early (T2) or late (T3) temperature shift-treatment. Moreover, fish were subjected to seawater challenge during and after the downstream migration peak time. Two allochtonous strains were used: Loire-Allier (LA) and Cong (CG). Without temperature shift (T1), significant differences between the strains were noticed in the peak date and maximum activity of gill Na/KATPase as well as in plasma sodium and potassium concentrations. For early (T2) and late (T3) temperature shift-treatments, gill Na/KATPase activity, plasma osmolality and ion concentrations were negatively influenced in both strains. After salinity challenge, the highest osmolality was measured in smolts subjected to the temperature shift. Predictably circulating levels of GH and IGF-1 changed over the smolting period but they did not explain the observed modifications in hypo-osmoregulatory abilities whatever the population. The results show a negative impact of a temperature shift on hypo-osmoregulatory capacities of smolts regardless of population differences in smoltification timing under conditions without temperature shift. The resilience of such physiological impact was sustained at least for 1 week, comforting the role of high temperature in influencing the rate of changes occurring during smoltification. Therefore, favouring the downstream migration to help smolts reach the sea faster may mitigate the impact of a rapid temperature increase.
人为利用水系可能导致支流和大河之间的温度波动，而有关这种波动对大西洋鲑渗透压调节能力的生理种群相关影响还没有很好的描述。我们模拟了默兹河流域的下游路径，以研究在幼鱼变态期间温度升高 5°C 对幼鱼低渗调节能力的影响。测试了三种温度制度：对照温度处理（T1）无温度变化、早期（T2）或晚期（T3）温度变化处理。此外，在下游洄游高峰期期间和之后，鱼类会受到海水的挑战。使用了两种异源种群：卢瓦尔-阿利埃（LA）和孔（CG）。在没有温度变化（T1）的情况下，两种种群在鳃 Na/KATP 酶的峰值日期和最大活性以及血浆钠和钾浓度方面存在显著差异。对于早期（T2）和晚期（T3）温度变化处理，两种种群的鳃 Na/KATP 酶活性、血浆渗透压和离子浓度均受到负面影响。在盐度挑战后，受温度变化影响的幼鱼的渗透压最高。可预测的是，GH 和 IGF-1 的循环水平在变态期间发生变化，但无论种群如何，它们都不能解释观察到的低渗调节能力的变化。研究结果表明，无论在没有温度变化的情况下幼鱼变态时间的种群差异如何，温度变化都会对幼鱼的低渗调节能力产生负面影响。这种生理影响的恢复力至少持续了 1 周，这证实了高温在影响幼鱼变态期间发生的变化率方面的作用。因此，促进下游洄游以帮助幼鱼更快到达大海可能会减轻快速升温的影响。
