Data from: Phytoplankton community interactions and environmental sensitivity in coastal and offshore habitats

Assessing the relative importance of environmental conditions and community interactions is necessary for evaluating the sensitivity of biological communities to anthropogenic change. Phytoplankton communities have a central role in aquatic food webs and biogeochemical cycles, therefore, consequences of differing community sensitivities may have broad ecosystem effects. Using two long-term time series (28 and 20 years) from the Baltic Sea, we evaluated coastal and offshore major phytoplankton taxonomic group biovolume patterns over annual and monthly time-scales and assessed their response to environmental drivers and biotic interactions. Overall, coastal phytoplankton responded more strongly to environmental anomalies than offshore phytoplankton, although the specific environmental driver changed with time scale. A trend indicating a state shift in annual biovolume anomalies occurred at both sites and the shift's timing at the coastal site closely tracked other long-term Baltic Sea ecosystem shifts. Cyanobacteria and the autotrophic ciliate Mesodinium rubrum were more strongly related than other groups to this trend with opposing relationships that were consistent across sites. On a monthly scale, biotic interactions within communities were rare and did not overlap between the coastal and offshore sites. Annual scales may be better able to assess general patterns across habitat types in the Baltic Sea, but monthly community dynamics may differ at relatively small spatial scales and consequently respond differently to future change.

对于评估生物群落对人为扰动的敏感性而言，明确环境条件与群落互作的相对重要性是必要前提。浮游植物群落（Phytoplankton communities）在水生食物网与生物地球化学循环中扮演核心角色，因此群落敏感性差异所引发的后果可能对生态系统产生广泛影响。本研究依托波罗的海（Baltic Sea）的两组长期时间序列（时长分别为28年与20年），解析了近岸与远岸主要浮游植物分类类群的生物体积（biovolume）在年际与月际时间尺度上的变化模式，并评估了其对环境驱动因子与生物互作的响应。整体来看，近岸浮游植物对环境异常（environmental anomalies）的响应强度高于远岸浮游植物，但具体的关键环境驱动因子会随时间尺度发生变化。两个采样点均呈现出年际生物体积异常值的状态转变（state shift）趋势，且近岸采样点的转变时序与波罗的海其他长期生态系统转变的时间高度吻合。蓝藻门（Cyanobacteria）与自养纤毛虫红色中缢虫（Mesodinium rubrum）与该趋势的相关性显著强于其他类群，二者呈现相反的相关关系，且该关系在两个采样点均保持一致。在月际尺度上，群落内部的生物互作十分罕见，且近岸与远岸站点的生物互作模式不存在重叠。年际尺度或许更适合用于解析波罗的海不同生境类型下的通用规律，但月际群落动态在较小空间尺度上可能存在差异，因此对未来环境变化的响应也可能有所不同。