As primary producers, phytoplankton play a pivotal role in the marine environment and are central to many biogeochemical processes. Changes to phytoplankton community composition could have major consequences for wider ecosystem functioning and may occur in response to climate change. Here we describe multi-decadal variability in phytoplankton community structure using taxonomic data from the Continuous Plankton Recorder collected in the North-East At lan tic from 1969−2013, using a total of 42 diatom and dinoflagellate taxa. We considered a range of characteristics of community structure, including taxonomic diversity and community stability and disorder, and how these characteristics change in response to sea surface temperature, mixed layer depth and the North Atlantic Oscillation. We found that phytoplankton community composition was largely stable on interannual timescales. A change in community composition occurred between 1985 and 1995 due to an increased dominance of 2 diatom taxa (Rhizosolenia styliformis and Thalassiosira spp.); however, after this period, the community returned to its previous composition. Further, a community disorder analysis found that phytoplankton compositional structure became more rigid in recent years, which may lead to an eventual community shift in the future. In contrast to previous studies that revealed relationships between total phytoplankton abundance or biomass and environmental forcing, we found that community structure had, at most, a very weak relationship with the environmental parameters tested. Changes to the physical environment may therefore have less influence at interannual timescales on phytoplankton community structure than previously thought.

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东北大西洋浮游植物群落组成的年际稳定性

作为初级生产者，浮游植物在海洋环境中起着举足轻重的作用，并且是许多生物地球化学过程的核心。浮游植物群落组成的变化可能对更广泛的生态系统功能产生重大影响，并可能因气候变化而发生。在这里，我们使用 1969 年至 2013 年在大西洋东北部收集的连续浮游生物记录仪的分类学数据，使用总共 42 个硅藻和甲藻类群，描述了浮游植物群落结构的多年变化。我们考虑了群落结构的一系列特征，包括分类多样性和群落稳定性和无序性，以及这些特征如何随着海面温度、混合层深度和北大西洋涛动而变化。我们发现浮游植物群落组成在年际时间尺度上基本稳定。由于 2 个硅藻类群（Rhizosolenia styliformis 和 Thalassiosira spp.）的优势增加，1985 年至 1995 年间群落组成发生了变化；然而，在这段时间之后，社区又恢复了以前的组成。此外，群落紊乱分析发现，近年来浮游植物的组成结构变得更加僵化，这可能导致未来最终的群落转变。与之前揭示浮游植物总丰度或生物量与环境强迫之间关系的研究相比，我们发现群落结构至多与测试的环境参数之间的关系非常微弱。