PDF(Pubmed)
Abstract：
Long-term ecological time series provide a unique perspective on the emergent properties of ecosystems. In aquatic systems, phytoplankton form the base of the food web and their biomass, measured as the concentration of the photosynthetic pigment chlorophyll a (chl a), is an indicator of ecosystem quality. We analyzed temporal trends in chl a from the Long-Term Plankton Time Series in Narragansett Bay, Rhode Island, USA, a temperate estuary experiencing long-term warming and changing anthropogenic nutrient inputs. Dynamic linear models were used to impute and model environmental variables (1959 to 2019) and chl a concentrations (1968 to 2019). A long-term chl a decrease was observed with an average decline in the cumulative annual chl a concentration of 49% and a marked decline of 57% in winter-spring bloom magnitude. The long-term decline in chl a concentration was directly and indirectly associated with multiple environmental factors that are impacted by climate change (e.g., warming temperatures, water column stratification, reduced nutrient concentrations) indicating the importance of accounting for regional climate change effects in ecosystem-based management. Analysis of seasonal phenology revealed that the winter-spring bloom occurred earlier, at a rate of 4.9 ± 2.8 d decade-1. Finally, the high degree of temporal variation in phytoplankton biomass observed in Narragansett Bay appears common among estuaries, coasts, and open oceans. The commonality among these marine ecosystems highlights the need to maintain a robust set of phytoplankton time series in the coming decades to improve signal-to-noise ratios and identify trends in these highly variable environments.
摘要：
长期生态时间序列为生态系统的出现特性提供了独特的视角。在水生系统中，浮游植物构成了食物网及其生物量的基础，测量为光合色素叶绿素a(chla)的浓度，是生态系统质量的指标。我们分析了纳拉甘西特湾长期浮游生物时间序列中chla的时间趋势，罗德岛,美国,经历长期变暖和人为营养输入变化的温带河口。动态线性模型用于估算和建模环境变量（1959年至2019年）和chla浓度（1968年至2019年）。观察到长期chla下降，年累积chla浓度平均下降49％，冬春开花幅度显着下降57％。chla浓度的长期下降与受气候变化影响的多个环境因素直接和间接相关(例如，变暖的温度，水柱分层，降低的养分浓度）表明在基于生态系统的管理中考虑区域气候变化影响的重要性。季节物候分析表明，冬春开花发生较早，以4.9±2.8d的速度进行十年-1。最后,在纳拉甘西特湾观察到的浮游植物生物量的高度时间变化在河口中很常见，海岸,和开放的海洋。这些海洋生态系统之间的共性突出表明，需要在未来几十年中保持一套稳健的浮游植物时间序列，以改善信噪比并确定这些高度变化环境中的趋势。
