Estación de Fotobiología Playa Unión, Casilla de Correos 15, 9103 Rawson, Chubut, Argentina.
Estación de Fotobiología Playa Unión, Casilla de Correos 15, 9103 Rawson, Chubut, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina.
Sci Total Environ. 2024 Mar 25;918:170644. doi: 10.1016/j.scitotenv.2024.170644. Epub 2024 Feb 5.
Extreme wind and rainfall events have become more frequent phenomena, impacting coastal ecosystems by inducing increased mixing regimes in the upper mixed layers (UML) and reduced transparency (i.e. browning), hence affecting phytoplankton photosynthesis. In this study, five plankton assemblages from the South Atlantic Ocean, from a gradient of environmental variability and anthropogenic exposure, were subjected to simulated extreme weather events under a global change scenario (GCS) of increased temperature and nutrients and decreased pH, and compared to ambient conditions (Control). Using multiple linear regression (MLR) analysis we determined that evenness and the ratio of diatoms/ (flagellates + dinoflagellates) significantly explained the variations (81-91 %) of the photosynthesis efficiency (i.e. P/ETR ratio) for each site under static conditions. Mixing speed and the optical depth (i.e. attenuation coefficient * depth, kz), as single drivers, explained 40-76 % of the variability in the P/ETR ratio, while GCS drivers <9 %. Overall, assemblages with high diversity and evenness were less vulnerable to extreme weather events under a GCS. Extreme weather events should be considered in global change studies and conservation/management plans as even at local/regional scales, they can exceed the predicted impacts of mean global climate change on coastal primary productivity.
极端风和降雨事件已成为更为频繁出现的现象，它们通过在上层混合层（UML）中诱导增加混合状态和降低透明度（即褐变），从而影响浮游植物光合作用，对沿海生态系统产生影响。在本研究中，来自南大西洋的五个浮游生物组合体，处于环境变异性和人为暴露的梯度下，在增加温度和营养物质以及降低 pH 值的全球变化情景（GCS）下，经受了模拟的极端天气事件，与环境条件（对照）进行了比较。使用多元线性回归（MLR）分析，我们确定均匀度和硅藻/（鞭毛藻+甲藻）的比值对于每个站点在静态条件下显著解释了光合作用效率（即 P/ETR 比值）变化的 81-91%。混合速度和光学深度（即衰减系数*深度，kz）作为单一驱动因素，解释了 P/ETR 比值变化的 40-76%，而 GCS 驱动因素<9%。总体而言，在 GCS 下，多样性和均匀度较高的组合体不易受到极端天气事件的影响。在全球变化研究和保护/管理计划中应考虑极端天气事件，因为即使在局部/区域范围内，它们也可能超过对沿海初级生产力的全球气候变化平均影响的预测。
