LAUSR

We studied the contribution of environmental and spatial factors in determining the metacommunity dynamics of benthic macroinvertebrates in ocean-exposed sandy beaches. A combination of different metacommunity models contributed to the structure of the benthic species, suggesting that the interplay of environmental and spatial factors played a key role in determining the beach community structure. Our study highlights the sensitivity of beach invertebrates to environmental factors such as morphodynamic descriptors, and to oceanographic-related variables (e.g., sea-water temperature). The results also suggest significant spatial signals at a large geographical scale. We applied two different species categorizations, high dispersive vs low dispersive and generalist vs specialist, to disentangle the roles of dispersal mode and habitat specialization in the beach metacommunity structure. The strength of the environmental and spatial factors varied depending on the category of species traits considered, emphasizing the value of using different groups of species in explaining variation in metacommunity dynamics. Low dispersive species showed a better ability to track environmental variability than high dispersive species, which were more spatially constrained. Habitat specialists were better able to track environmental variability than generalists, which were mainly predicted by pure spatial factors. A better understanding of the metacommunity dynamics using different species categorizations can help to improve our predictions about exposed beach community structure, and to prioritize management actions to cope with biodiversity loss in such superlative marine environment.