Coupled effects of environment, space and ecological engineering on seafloor beta-diversity

One of the challenges in modern ecology is reconciling how biotic interactions and abiotic factors are interwoven drivers of community assembly. β-diversity is a measure of the variation in species composition across space and time. The drivers of variability in β-diversity are thus responsible for dictating the trajectory of assembling communities. With data from multiscale surveys conducted in three marine intertidal sandflats, we aimed to determine the relative importance and interdependencies of biotic engineering, environment and spatial distances for β-diversity. In each sandflat, macrofauna and environmental properties were assessed in 400 samples collected at different spatial distances over 300 000 m². The role of environmental variability in driving patterns in β-diversity and species turnover was dependent on the abundances of ecosystem engineers and spatial connectivity among seascapes as shown by the variance explained by the interaction terms in the variance partitioning. Our results highlight the interdependence between space, environment and species interactions in driving community assembly. Given that most models aiming to explain β-diversity variation only consider abiotic factors, our findings call for the incorporation of biotic interactions into these models and we argue that this is essential for understanding resilience to environmental change. The degree of interdependence between environment, space and biotic interactions in driving ecological assembly is pivotal to our understanding of how biodiversity will respond to predicted changes in habitats, environment and key species distributions.