Characterization of Intertidal Macrofaunal Communities of Two Sandy Beaches under Different Anthropogenic Pressures

The macrofauna in the intertidal zone of sandy beaches provides the trophic connectivity between land and sea, by linking microbiome, meiofauna, and megafauna, representing a food source for several terrestrial animals, including shorebirds and mammals. However, the macrozoobenthos in urbanised beaches is subjected to intense disturbances, such as breakwater barriers and tourism, which limit or impede the energy transfer from the marine to the terrestrial habitats. Because the information about diversity and abundance of the macrozoobenthos of the intertidal zone on the Mediterranean sandy coasts is scant, the main objective of this study is to increase the knowledge on the macrofauna living in this habitat and to identify taxa sensitive to cumulative human-induced stresses. To achieve this purpose, the structure and dynamics of macrozoobenthic communities from (1) a highly frequented beach characterized by breakwater barriers and (2) a marine protected area (MPA) in the Adriatic Sea were compared. The hypotheses that macrofauna composition and abundance changed in the two sites and over time were tested. Results highlighted that the macrozoobenthos in the MPA is mainly dominated by juvenile bivalves, which peaked from autumn to winter, and to a lesser extent by ostracods and mysids. Conversely, ostracods and the bivalve Lentidium mediterraneum (O. G. Costa, 1830) are particularly abundant in the highly disturbed beach, while the gastropod Tritia neritea (Linnaeus, 1758) increased only during summer. A possible combined effect of breakwater barriers and intense trampling has been theorized to explain the main differences between the two sites especially in the summer.