Instituto Argentino de Oceanografía (CONICET-UNS), Camino La Carrindanga km 7.5, 8000 Bahía Blanca, Argentina.
GEOMAR Helmholtz Centre for Ocean Research Kiel, Marine Ecology/Food Webs, Düsternbrooker Weg 20, 24105 Kiel, Germany.
Sci Total Environ. 2017 Dec 31;609:1390-1400. doi: 10.1016/j.scitotenv.2017.08.002. Epub 2017 Aug 6.
Estuaries are among the most valuable aquatic systems by their services to human welfare. However, increasing human activities at the watershed along with the pressure of climate change are fostering the co-occurrence of multiple environmental drivers, and warn of potential negative impacts on estuaries resources. At present, no clear understanding of how coastal ecosystems will respond to the non-stationary effect of multiple drivers. Here we analysed the temporal interaction among multiple environmental drivers and their changing priority on shaping phytoplankton response in the Bahía Blanca Estuary, SW Atlantic Ocean. The interaction among environmental drivers and the number of significant direct and indirect effects on chlorophyll concentration increased over time in concurrence with enhanced anthropogenic stress, changing winter climate and wind patterns. Over the period 1978-1993, proximal variables such as nutrients, water temperature and salinity, showed a dominant effect on chlorophyll, whereas in more recent years (1993-2009) climate signals (SAM and ENSO) boosted indirect effects through its influence on precipitation, wind, water temperature and turbidity. Turbidity emerged as the dominant driver of chlorophyll while in recent years acted synergistically with the concentration of dissolved nitrogen. As a result, chlorophyll concentration showed a significant negative trend and a loss of seasonal peaks reflecting a pronounced reorganisation of the phytoplankton community. We stress the need to account for the changing priority of drivers to understand, and eventually forecast, biological responses under projected scenarios of global anthropogenic change.
河口是对人类福利最具价值的水生系统之一。然而，流域内人类活动的增加以及气候变化的压力，促使多种环境驱动因素同时出现，并对河口资源构成潜在的负面影响。目前，人们还不清楚沿海生态系统将如何应对多种驱动因素的非平稳效应。在这里，我们分析了多个环境驱动因素之间的时间相互作用及其对巴伊亚布兰卡河口浮游植物响应的塑造作用的变化优先级，该河口位于西南大西洋。随着人为压力的增强、冬季气候和风向模式的变化，环境驱动因素之间的相互作用以及对叶绿素浓度有直接和间接显著影响的因素数量随着时间的推移而增加。在 1978-1993 年期间，营养物质、水温和盐度等近端变量对叶绿素表现出主导作用，而在最近几年（1993-2009 年），气候信号（SAM 和 ENSO）通过对降水、风和水温以及浊度的影响，增强了间接影响。浊度作为叶绿素的主要驱动因素出现，而在最近几年与溶解氮浓度协同作用。结果，叶绿素浓度呈显著负趋势，季节性峰值消失，反映出浮游植物群落的明显重组。我们强调需要考虑驱动因素变化的优先级，以了解并最终预测在全球人为变化预测情景下的生物响应。
