Structure and spatial organization of macrobenthic fauna of intertidal habitats frequented by wintering shorebirds at Merja Zerga lagoon (Moroccan Ramsar Site)

Merja Zerga is the most important wetland for wintering shorebirds in Morocco. To understand the role of intertidal habitats as feeding areas, a study that aims to analyse the composition, structure and spatial organization of macrobenthic fauna in the main habitats frequented by shorebirds has been conducted. From the analysis of 570 samples distributed over 19 stations, 46 species of benthic macrofauna, dominated by Molluscs and Polychaetes, were identified. Densities ranged from 305 to 25 663 individuals.m(-2), with an average of 5 764 ind.m(-2), and biomasses ranged from 3.92 to 52.65 g.m(-2), with an average of 20.07 g.m(-2). Four benthic assemblages were identified, distributed along a downstream-upstream gradient. Hydrological and sedimentary parameters, as well as the presence or absence of seagrass beds, were the main factors that structure the distribution and the functioning of benthic assemblages. Distribution maps of benthic assemblages, representing the main prey for shorebirds, are essential tools for managers to identify areas with high conservation issues for aquatic birds.