Instituto de Oceanografia, Universidade Federal do Rio Grande, Rio Grande, (RS), Brazil.
National Research Institute for Agriculture, Food and the Environment (INRAE), Bordeaux, France.
Mar Environ Res. 2024 Oct;201:106698. doi: 10.1016/j.marenvres.2024.106698. Epub 2024 Aug 17.
Climate and anthropogenic impacts are prevalent in marine and estuarine ecosystems. Rapid environmental changes have altered biological diversity and the ecological services associated with ecosystems around the world. The consequences of these impacts on estuarine ecosystems are worrying, given that estuaries are essential habitats for maintaining the diversity of species functions, as they act as sources for larger ecosystems through the recruitment and replacement of species. Through long-term standardized monitoring (1996-2019), we evaluated the temporal variability of the functional structure of fish species in a subtropical estuary using Principal Component Analysis (PCA), and their relationship with environmental, climatic, and anthropogenic variables using Generalized Additive Models (GAM). We investigate the hypothesis that natural disturbances associated with El Niño events and anthropogenic ones related with changes in the estuary morphology will lead to a decrease in the diversity of functions of the fish assemblage in the Patos Lagoon Estuary in south Brazil (32°S). Our findings suggest an overall downward trend in the fish functional structure, especially in the second half (2006-2019) of the time series, which seems to be associated with a combination of abiotic effects (salinity and temperature), global climate phenomena (ENSO phases) and anthropogenic impacts (changes in the morphology of the estuarine mouth and its connection with the sea). These findings rise concern considering the current climate change scenario, where phenomena such as El Niño may become more frequent and intense. Therefore, the evidence from this study suggests that extreme natural climatic events in synergy with anthropogenic disturbances may imply biodiversity losses over time and, consequently, loss of ecosystem processes in a subtropical estuary.
气候和人为因素对海洋和河口生态系统有广泛影响。快速的环境变化改变了生物多样性和与世界各地生态系统相关的生态服务。鉴于河口是维持物种功能多样性的重要栖息地，因为它们通过物种的补充和替代作用成为更大生态系统的源泉，因此这些影响对河口生态系统的后果令人担忧。通过长期标准化监测（1996-2019 年），我们使用主成分分析（PCA）评估了亚热带河口鱼类物种功能结构的时间变化，并使用广义加性模型（GAM）评估了其与环境、气候和人为变量的关系。我们研究了以下假设：与厄尔尼诺事件相关的自然干扰和与河口形态变化相关的人为干扰将导致巴塔哥尼亚拉戈亚河口（南纬 32°）鱼类组合的功能多样性减少。我们的研究结果表明鱼类功能结构总体呈下降趋势，尤其是在时间序列的后半段（2006-2019 年），这似乎与非生物效应（盐度和温度）、全球气候现象（ENSO 阶段）和人为影响（河口形态变化及其与海洋的连接）的组合有关。考虑到当前的气候变化情景，厄尔尼诺等现象可能变得更加频繁和强烈，这些发现令人担忧。因此，本研究的证据表明，极端自然气候事件与人为干扰协同作用可能意味着生物多样性随着时间的推移而丧失，从而导致亚热带河口生态系统过程的丧失。
