INRAE, Unité EABX-Écosystèmes Aquatiques et Changements Globaux, HYNES (Irstea-EDF R&D), 50 avenue de Verdun, 33612 Cestas Cedex, France.
EDF Recherche et Développement, Laboratoire National d'Hydraulique et Environnement, HYNES (Irstea-EDF R&D), 6 quai Watier, 78401 Chatou Cedex, France.
Proc Biol Sci. 2021 Dec 8;288(1964):20211882. doi: 10.1098/rspb.2021.1882.
In freshwater ecosystems, water temperature and discharge are two intrinsically associated triggers of key events in the life cycle of aquatic organisms such as the migration of diadromous fishes. However, global changes have already profoundly altered the thermal and hydrological regimes of rivers, affecting the timing of fish migration as well as the environmental conditions under which it occurs. In this study, we focused on Atlantic salmon (), an iconic diadromous species whose individuals migrate between marine nursery areas and continental spawning grounds. An innovative multivariate method was developed to analyse long-term datasets of daily water temperature, discharge and both salmon juvenile downstream and adult upstream migrations in three French rivers (the Bresle, Oir and Nivelle rivers). While all three rivers have gradually warmed over the last 35 years, changes in discharge have been very heterogeneous. Juveniles more frequently used warmer temperatures to migrate. Adults migrating a few weeks before spawning more frequently used warm temperatures associated with high discharges. This has already led to modifications in preferential niches of both life stages and suggests a potential mismatch between these populations' ecological preference and changes in their local environment due to global change.
在淡水生态系统中，水温与流量是水生生物生命周期中关键事件的两个内在关联触发因素，如洄游鱼类的洄游。然而，全球变化已经深刻地改变了河流的热和水文状况，影响了鱼类洄游的时间以及其发生的环境条件。在这项研究中，我们专注于大西洋鲑（Salmo salar），这是一种标志性的洄游物种，其个体在海洋育肥区和大陆产卵场之间迁徙。我们开发了一种创新的多元分析方法，来分析法国三条河流（布雷勒河、乌尔河和尼韦勒河）中每日水温、流量以及鲑鱼幼鱼下游和成鱼上游洄游的长期数据集。尽管过去 35 年来这三条河流的水温都在逐渐升高，但流量的变化却非常不均匀。幼鱼更频繁地利用温暖的水温进行洄游。在产卵前几周洄游的成鱼更频繁地利用与高流量相关的温暖水温。这已经导致了两个生命阶段的优先生态位发生了改变，并表明由于全球变化，这些种群的生态偏好与其当地环境的变化之间可能存在不匹配。
