Ecological Questions 31 (2020) 4: 53 -65 http://dx.doi.org/10.12775/EQ.2020.028 Bathymetrical and temporal variations in soft-bottom molluscan assemblages in the coastal area facing the Sarno River mouth (Mediterranean Sea, Gulf of Naples) Luigia Donnarumma, Roberto Sandulli, Luca Appolloni*, Federica Ferrigno, Francesco Rendina, Floriana Di Stefano, Giovanni Fulvio Russo Department of Science and Technology, Parthenope University of Naples, 80143 Naples, Italy; CoNISMa (National Interuniversity Consortium for Marine Sciences), 00196 Rome, Italy *Corresponding author e-mail:
[email protected] Received: 15 May 2020 / Accepted: 2 July 2020 Abstract – Molluscan assemblage of coastal area facing the very polluted Sarno River estuary to offshore (Gulf of Naples, Italy) was studied, focusing on temporal and depth-related distribution of species diversity, quali-quantitative composition and trophic guilds structure. A total of 9 stations, at depths ranging between 7 and 95m, were sampled in triplicate by means of a 0.17 m2 Van Veen grab in four sampling occasions (2 seasons, winter and summer, during 2 years, 2015 and 2016). A total of 1,744 individuals, belonging to 78 species and 3 classes (Bivalvia, Gastropoda and Scaphopoda), was recorded. Bivalves, followed by gastropods, qualitatively and quantitatively dominated the mollusc assemblages and both these taxonomic groups showed the highest values in the shallower sta- tions down to about 25 m depth. In the deeper stations, only the bivalve taxon was dominant, even though exhibiting a much lower species richness and abundance. On the overall, the molluscan species were ascribed to 6 feeding guilds: Suspension and deposit feeders were the dominant trophic groups, occurring at all stations along the bathymetrical gradient, while predators, detritus feed- ers, ecto-parasites and scavengers were poorly represented and mainly occurred in the shallowest stations.