FEHM-Lab (Freshwater Ecology, Hydrology and Management), Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals, Institut de Recerca de l'Aigua (IdRA), Universitat de Barcelona, Barcelona, Spain; Rui Nabeiro' Biodiversity Chair, MED - Mediterranean Institute for Agriculture, Environment and Development, Universidade de Évora, Évora, Portugal.
BETA Technological Center, University of Vic- Central University of Catalonia (UVic-UCC), Vic, Spain.
Environ Pollut. 2022 Nov 15;313:120127. doi: 10.1016/j.envpol.2022.120127. Epub 2022 Sep 8.
Freshwater ecosystems are becoming saltier due to human activities. The effects of increased salinity can lead to cascading trophic interactions, affecting ecosystem functioning and energy transfer, through changes in community and size structure. These effects can be modulated by other environmental factors, such as nutrients. For example, communities developed under eutrophic conditions could be less sensitive to salinization due to cross-tolerance mechanisms. In this study, we used a mesocosm approach to assess the effects of a salinization gradient on the zooplankton community composition and size structure under eutrophic conditions and the cascading effects on algal communities. Our results showed that zooplankton biomass, size diversity and mean body size decreased with increased chloride concentration induced by salt addition. This change in the zooplankton community did not have cascading effects on phytoplankton. The phytoplankton biomass decreased after the chloride concentration threshold of 500 mg L was reached, most likely due to direct toxic effects on the osmotic regulation and nutrient uptake processes of certain algae rather than as a response to community turnover or top-down control. Our study can help to put in place mitigation strategies for salinization and eutrophication, which often co-occur in freshwater ecosystems.
由于人类活动，淡水生态系统的盐度正在增加。盐分增加的影响会通过群落和大小结构的变化，导致级联营养相互作用，从而影响生态系统功能和能量转移。这些影响可以通过其他环境因素（如营养物）来调节。例如，在富营养化条件下形成的群落由于交叉耐受机制，可能对盐度变化的敏感性较低。在这项研究中，我们使用中观模型方法来评估在富营养化条件下，盐度梯度对浮游动物群落组成和大小结构的影响，以及对藻类群落的级联效应。我们的结果表明，随着盐度增加引起的氯化物浓度的增加，浮游动物生物量、大小多样性和平均体型减小。浮游动物群落的这种变化对浮游植物没有级联效应。当氯化物浓度达到 500mg/L 的阈值后，浮游植物生物量下降，这很可能是由于某些藻类的渗透调节和营养吸收过程受到直接毒性影响，而不是对群落更替或自上而下控制的反应。我们的研究可以帮助制定针对淡水生态系统中经常同时发生的盐度和富营养化的缓解策略。
