Sandy Beach Heterogeneity: Intertidal and Supralittoral Communities

Surf zones, beaches and dunes compose the Littoral Active Zones (LAZ) in coastal areas. Sandy beaches encompass the intertidal-supralittoral interface of LAZ and are characterized by discrete assemblages, tightly related to the physical constrains and habitats where marine, semi-terrestrial and terrestrial organisms live. Crustaceans, molluscs and polychaetes dominate beach communities in intertidal zones, whilst insects become representative in supralittoral. Communities are relatively similar worldwide, being frequently dominated by typical families, with few specificities according to morpho dynamics, latitude and tide regime. Communities are structured mainly by individual responses of species to physical drivers on several spatial dimensions. The Swash Exclusion, Multicausal Environmental Severity and Habitat Harshness hypotheses have been corroborated for explaining the higher richness and density of marine macroinvertebrates on dissipative beaches compared to reflective ones. Nevertheless, supralittoral communities still lack depiction of patterns and processes, since communities of swash and upper zones can be driven by independent factors. For intertidal communities dominated by marine organisms, grain size, beach slope, tide regime, temperature and primary productivity have been considered the main drivers of richness at macroscales. Nevertheless, environmental disturbances, habitat heterogeneity, ecological interactions, and meta-populations connectivity are still neglected in studies on/about community ecology of intertidal and supralittoral zones.