Appreciating how the processes of community assembly vary across multiple spatial scales and environmental gradients remains a crucial issue in ecology.
This study* aimed to disentangle the drivers of diversity and composition of seaweed communities through a gradient of spatial scales along the Brittany coastline. We compared (i) the relative importance of deterministic and stochastic processes, (ii) the environmental correlates of community composition, and (iii) the scale of variation in community composition for seaweed communities located at two different tidal heights.
Our results indicate that seaweed communities were largely shaped by deterministic processes, although the relative importance of deterministic processes was greater for communities of the infralittoral fringe than for subtidal communities. Sea surface temperature and geophysical variables were correlates of community composition at the two tidal heights; additionally, waves and current were correlated with the composition of the communities of the infralittoral fringe while kelp density was correlated with the composition of subtidal communities. Variation in community composition was observed at a finer scale for infralittoral fringe than for subtidal communities.
Our work suggests that the relative importance of deterministic and stochastic processes in structuring seaweed communities varies across tidal heights. Furthermore, we highlighted that the nature of environmental correlates and the spatial scale at which they were good correlates of community composition also vary across tidal heights and may therefore be useful to broaden our understanding of community assembly across vertical gradients.
BOREA contact: Marine Robuchon, marine.robuchon@mnhn.fr
* Robuchon M, Valero M, Thiébaut E, Le Gall L. Multi-scale drivers of community diversity and composition across tidal heights: an example on temperate seaweed communities. Journal of Ecology, in press.
