Biodiversity Loss Threatens the Current Functional Similarity of Beta Diversity in Benthic Diatom Communities

Abstract

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.

Diversity and distribution across a large environmental and spatial gradient: Evaluating the taxonomic and functional turnover, transitions and environmental drivers of benthic diatom communities

“…However, functional beta diversity remained low; that is, species were replaced by taxonomically new but functionally similar species along the gradient. Similar results of low functional beta diversity despite high taxonomic beta diversity have been found before across short spatial gradients in estuaries (Villéger et al, 2012 in a tropical estuary;Virta et al, 2020b), but our large spatial gradient makes the result interesting. It seems that the functional characteristics of microphytobenthos needed for efficient benthic ecosystem functioning are very similar in very different environments.…”

Exploring Multiple Aspects of Taxonomic and Functional Diversity in Microphytobenthic Communities: Effects of Environmental Gradients and Temporal Changes

“…This outcome may indicate the effects of the strong winds in September and the subsequently higher windinduced wave disturbance in rock pools located on islands that were farther from the mainland. Wind exposure, which is typically higher on more distant islands (Korvenpää et al, 2003), has been shown to influence the diatom community composition in the Baltic Sea coastal region (Virta et al, 2021) and could possibly explain why species richness tends to be lower on the more distant, exposed rock pool systems. Higher levels of wave exposure have also been associated with a lower species richness of diatom communities in the northern Baltic Sea (Busse and Snoeijs, 2003).…”

“…The outcome may, though, be dependent on the spatial extent of the study because at large spatial scales spanning distinct geographical regions, regional specificity of species composition may hinder the ability of species composition to track the environmental changes (Soininen et al, 2016). On smaller spatial extents, evidence for stronger correlations between the environment and taxonomic composition than functional composition has been found for diatoms (Virta et al, 2021), as well as other organism groups, such as macroinvertebrates (Heino and Tolonen, 2017) and fish (Villéger et al, 2012). Taken together, the results suggest that although there are apparent changes in the species composition and environmental conditions between rock pools, the functional composition of diatom communities remains rather similar.…”

Environmental Heterogeneity Determines Diatom Colonisation on Artificial Substrata: Implications for Biomonitoring in Coastal Marine Waters

“…Information on spatial beta diversity is important for our understanding of ecosystem processes such as biogeochemical cycles and trophic interactions. Diverse species assemblages, including that of benthic diatom communities (Virta et al, 2021), impart various ecological roles in an ecosystem, highlighting the crucial role of biodiversity in providing multiple ecosystem functions (see Mori et al, 2018). Therefore, the spatial taxonomic variation observed in this study highlights the diatom biodiversity present at a local scale.…”