Studying biodiversity–ecosystem function relationships in experimental microcosms among islands

Abstract

Ecological studies on islands have provided fundamental insights into the mechanisms underlying biodiversity of larger organisms, but we know little about the factors affecting island microbial biodiversity and ecosystem function. We conducted a field experiment on five Baltic Sea islands where we placed aquatic microcosms with different levels of salinity mimicking environmental stress and allowed diatoms to colonize the microcosms via the air. Using structural equation models (SEM), we investigated the interconnections among environmental and dispersal-related factors, diatom biodiversity, and ecosystem productivity (represented by chlorophyll a concentration). We also tested whether the body size structure of the community influences productivity together with biodiversity. In SEMs, we found no relationship between species richness or evenness and productivity. However, productivity increased with increasing mean body size of species in the communities. The effects of environmental stress on both biodiversity and ecosystem productivity were highlighted as species richness and evenness declined, whereas productivity increased at the highest salinity levels. In addition to salinity, wind exposure affected both biodiversity metrics and productivity. This study provides new insights into microbial community assembly in a field experimental setting

Elevational microbial β diversity and community assembly processes in subarctic ponds

“…For bacterial communities, the relative influence of deterministic and stochastic processes has also been shown to vary along a desiccation gradient, with communities subject to drought and a higher level of abiotic stress being more affected by deterministic processes (Valverde et al, 2014). Furthermore, in a field experiment with passive colonisation of diatoms to microcosms with different levels of salinity indicating environmental stress, the influence of deterministic processes was strongest under extreme conditions at high salinity that exceeded salinities of natural aquatic ecosystems in and around the study region (Teittinen et al, 2022).…”

“…The processes affecting community assembly are, however, context‐dependent and dynamic, and no consensus has been reached as to when and why certain processes prevail over the others (Langenheder & Lindström, 2019 and references therein). The relative influence of the two processes on microbial community assembly may change along elevational (Zeng et al, 2016) or environmental gradients, such as pH (Tripathi et al, 2018) or salinity (Teittinen et al, 2022). The influence of deterministic processes often increases in more extreme, stressful environments imposed by strong environmental filters (Tripathi et al, 2018), such as at high elevations.…”