The link between harmful algal blooms, phytoplankton community dynamics and global environmental change is not well understood. To tackle this challenging question, a new method was used to reveal how phytoplankton communities responded to environmental change with the occurrence of an harmful algae, using the coastal waters of the eastern English Channel as a case study. The great interannual variability in the magnitude and intensity of Phaeocystis spp. blooms, along with diatoms, compared to the ongoing gradual decrease in anthropogenic nutrient concentration and rebalancing of nutrient ratios; suggests that other factors, such as competition for resources, may also play an important role. A realized niche approach was used with the Outlying Mean Index analysis and the dynamics of the species’ realized subniches were estimated using the Within Outlying Mean Indexes calculations under low (L) and high (H) contrasting Phaeocystis spp. abundance. The Within Outlying Mean Indexes allows the decomposition of the realized niche into realized subniches, found within the subset of habitat conditions and constrained by a subset of a biotic factor. The two contrasting scenarios were characterized by significantly different subsets of environmental conditions and diatom species (BV-step analysis), and different seasonality in salinity, turbidity, and nutrients. The subset L environmental conditions were potentially favorable for Phaeocystis spp. but it suffered from competitive exclusion by key diatom species such as Skeletonema spp., Thalassiosira gravida, Thalassionema nitzschioides and the Pseudo-nitzchia seriata complex. Accordingly, these diatoms species occupied 81% of Phaeocystis spp.'s existing fundamental subniche. In contrast, the greater number of diatoms, correlated with the community trend, within subset H exerted a weaker biological constraint and favored Phaeocystis spp. realized subniche expansion. In conclusion, the results strongly suggest that both abiotic and biotic interactions should be considered to understand Phaeocystis spp. blooms with greater consideration of the preceeding diatoms. HABs needs must therefore be studied as part of the total phytoplankton community.

有害藻华，浮游植物群落动态与全球环境变化之间的联系尚未得到很好的理解。为了解决这个具有挑战性的问题，采用了一种新方法，以英格兰东部英吉利海峡的沿海水域为例，揭示了浮游植物群落对环境变化的反应，即有害藻类的发生。囊藻的大小和强度的年际变化很大spp。与人为引起的营养物浓度不断降低和营养物比例重新平衡相比，花粉与硅藻一起开花；表明其他因素，例如对资源的竞争，也可能起重要作用。甲实现利基方法用边远平均数指数分析中使用与实现subniches物在低（L）和高（H）对比使用在边远平均数指标计算估计出的物种的动态棕spp。丰富。外部均值范围内的索引允许将已实现的生态位分解为已实现的子位，这些位在栖息地条件的子集内并受生物因子的子集约束。两种截然不同的情况的特征是环境条件和硅藻种类的子集显着不同（BV步骤分析），盐度，浊度和养分的季节性不同。子集L的环境条件可能对Phaeocystis spp有利。但它通过关键硅藻如从竞争性排斥遭遇肋骨属，海链孕妇，菱形海线藻和伪nitzchia seriata复杂的。因此，这些硅藻种类占据了81％，棕囊藻属。公司现有基础subniche。相比之下，子集H内硅藻数量的增加与群落的变化趋势相关，则生物学上的限制较弱，并有利于囊藻属（Phaeocystis spp）。实现子市场扩张。总之，结果强烈建议应同时考虑非生物和生物相互作用，以了解Phaeocystis spp。开花时，会更先考虑硅藻。因此，必须将HAB的需求作为整个浮游植物群落的一部分进行研究。