The global biodiversity loss has increased the need to understand the effects of decreasing diversity, but our knowledge on how species loss will affect the functioning of communities and ecosystems is still very limited. Here, the levels of taxonomic and functional beta diversity and the effect of species loss on functional beta diversity were investigated in an estuary that provides a naturally steep environmental gradient. The study was conducted using diatoms that are among the most important microorganisms in all aquatic ecosystems and globally account for 40% of marine primary production. Along the estuary, the taxonomic beta diversity of diatom communities was high (Bray-Curtis taxonomic similarity 0.044) and strongly controlled by the environment, particularly wind exposure, salinity, and temperature. In contrast, the functional beta diversity was low (Bray-Curtis functional similarity 0.658) and much less controlled by the environment. Thus, the diatom communities stayed functionally almost similar despite large changes in species composition and environment. This may indicate that, through high taxonomic diversity and redundancy in functions, microorganisms provide an insurance effect against environmental change. However, when studying the effect of decreasing species richness on functional similarity of communities, simulated species loss to 45% of the current species richness decreased functional similarity significantly. This suggests that decreasing species richness may increase variability and reduce the stability and resilience of communities. These results highlight the importance of high taxonomic biodiversity for the stable functioning of benthic communities.

全球生物多样性的丧失使人们越来越需要了解减少多样性的影响，但是我们对物种丧失将如何影响社区和生态系统功能的知识仍然非常有限。在这里，在提供自然陡峭环境梯度的河口中研究了分类学和功能性β多样性的水平以及物种损失对功能性β多样性的影响。这项研究是使用硅藻进行的，硅藻是所有水生生态系统中最重要的微生物之一，全球占海洋初级生产的40％。沿河口，硅藻群落的生物分类学β多样性很高（Bray-Curtis生物分类学相似度为0.044），并受到环境的强烈控制，尤其是风，盐度和温度。相反，功能性β多样性低（Bray-Curtis功能相似性0.658），受环境控制的程度低得多。因此，尽管物种组成和环境发生了很大的变化，硅藻群落在功能上仍然几乎相似。这可能表明，通过高度的分类学多样性和功能冗余，微生物可提供抵御环境变化的保障作用。但是，在研究降低物种丰富度对社区功能相似性的影响时，模拟物种流失至当前物种丰富度的45％会显着降低功能相似性。这表明减少物种丰富度可能会增加变异性并降低社区的稳定性和复原力。