Limnetica 33

This work studied the spatial and seasonal variations of the macrobenthic community structure of the Minho estuary saltmarsh, which involved examining the relationships between the macrobenthic community and the abiotic characteristics of the surrounding sediments: texture, organic matter content and metal (Cd, Cr, Cu, Fe, Ni, Pb and Zn) concentrations. These abiotic characteristics showed significant (p < 0.05) spatial and seasonal variations that demonstrated the complex sedimentary dynamics of this saltmarsh. The macrobenthic community structure consisted of 37 taxa belonging to 5 phyla: Annelida (10 taxa), Mollusca (4 taxa), Arthropoda (21 taxa), Chordata (1 taxon) and Sipuncula (1 taxon). The mean annual abundance was 1530 ind/m², and the most abundant species were Cyathura carinata, Scolelepis squamata and Hediste diversicolor. The macrobenthic community showed no standard spatial distribution throughout the saltmarsh, and species abundances showed high seasonal variations that were directly dependent on the natural environmental conditions of each season. Although the Minho estuary saltmarsh showed evidence of anthropogenic contamination by metals, the macrobenthic community was not significantly influenced by their presence, and the main structuring factor was the texture of the sediments.