From 2000 to 2016, substantial changes in biomass and community structure of small pelagic fish and mesozooplankton have been reported in the Bay of Biscay. Since significant relationships have been found between phytoplankton chlorophyll a and mesozooplankton as well as between phytoplankton chlorophyll a and shifts in sardine body condition, it was hypothesized that phytoplankton communities may have also been affected during this period and may have played a role in these changes. However, the available data were insufficient to validate this hypothesis and the causes of these changes remained unexplained. The present study analyzed a spatio-temporal marine microphytoplankton dataset collected during the annual PELGAS (PELagiques GAScogne) surveys from 2003 to 2014. The thorough analysis of microphytoplankton taxonomic composition, with an approach integrating the relative role of environmental conditions as well as biotic interactions and applying the concept of ecological niche, confirmed that significant modifications in microphytoplankton community structure occurred during this period. Temporal changes were stronger than spatial differences at these sampling scales. Three main periods, 2003–2005, 2006 and 2007–2014, showing different community structure, diversity and dominant taxonomic units were highlighted. Twenty eight taxonomic units were involved in these community changes. Among them, five were identified as the protagonists (Pseudo-nitzschia spp., Gymnodinium spp. + Gyrodinium spp., Leptocylindrus danicus, Leptocylindrus minimus and Chaetoceros sp.). Variations in water temperature and equivalent freshwater depth constrained the realized ecological niches of these species and explained, at least in part, changes in community structure. This study stresses the need to improve our knowledge of phytoplankton species ecological niches and to take into account biotic interactions for a thorough understanding of the processes shaping plankton communities and the resulting diversity patterns.

从2000年到2016年，据报道，比斯开湾的小中上层鱼类和中层浮游生物的生物量和群落结构发生了实质性变化。由于显著的关系已被发现之间的浮游植物的叶绿素一和浮游动物之间以及浮游植物的叶绿素一以及沙丁鱼身体状况的变化，据推测在此期间浮游植物群落也可能受到影响，并可能在这些变化中发挥了作用。但是，可用数据不足以验证这一假设，而这些变化的原因仍无法解释。本研究分析了2003年至2014年年度PELGAS（PELagiques GAScogne）年度调查期间收集的时空海洋微浮游植物数据集。对微浮游植物分类学组成进行了全面分析，该方法整合了环境条件的相对作用以及生物相互作用和应用生态位概念，证实了在此期间微浮游植物群落结构发生了重大变化。在这些采样尺度上，时间变化要强于空间差异。重点介绍了2003-2005年，2006年和2007-2014年这三个主要时期，显示出不同的社区结构，多样性和主要的分类单位。有28个分类单位参与了这些社区变更。其中有五人被认定为主角（拟南芥属。，Gymnodinium spp 。+ Gyrodinium spp 。，Deptocylindrus danicus，Leptocylindrus minimus和Chaetoceros sp 。）。水温的变化和等效的淡水深度限制了这些物种已实现的生态位，并至少部分解释了群落结构的变化。这项研究强调有必要提高我们对浮游植物物种生态位的认识，并考虑到生物相互作用，以便对形成浮游生物群落的过程和由此产生的多样性模式有透彻的了解。