Patterns of diversity in subtidal marine macrofaunal communities: Insights from a semi-enclosed bay system in the Northeast Atlantic

The complexity of describing patterns and scales of variation in the distribution of species has created a delay in our understanding of the natural world. Understanding ecological functioning is essential to develop ecosystem management projects and to uphold conservation measures. The objective of the present study was to describe the variation in the structure of subtidal marine macrofaunal communities in a semi-enclosed bay system in the Northeast Atlantic to determine the relative importance of environmental conditions (e.g., water depth and position in the Ria) and processes (e.g., colonisation). Four different sites were selected along the Ria de Vigo, two sampling sites were allocated to the outermost part of the Ria and the other two sampling sites in the middle part of the Ria, both with different depths each (4-5 m and 11-12 m), and sampled at 1-, 3-, and 6- months of colonisation. Our results suggest a distinction between the community 1 month of colonisation and the remaining, with the Mollusca and Arthropoda species responsible for creating the most dissimilarities. At a local diversity level, the communities did not reveal significant differences in the factor's 'depth' or 'position in the Ria'. Through the application of beta diversity, significant patterns of variation emerged, revealing the significant importance of the deeper sites in maintaining unique and diverse communities in that region.