Distribution patterns of coastal fish assemblages associated with different rocky substrates in Asinara Island National Park (Sardinia, Italy)

Studies on ichthyofauna provide essential information for suitable management of a marine protected area. Fish assemblages associated with granite and schist substrates were studied by visual census at four different depth levels from 0 to 30 metres, in Asinara Island National Park (NW Sardinia, Italy). Forty-seven fish species were recorded with Labridae (12 species), Sparidae (10) and Serranidae (4) being the families with most species. Chromis chromis were most abundant, followed by Diplodus vulgaris and Coris julis. Multi Dimensional Scaling plots showed a clear-cut difference only for fish assemblages of the 4-7 m stratum while Analysis of Similarities tests for substrate and sites at different depth levels found significant differences only among sites. ANOVA performed on species richness, total fish abundance (mean individuals number 125 m-2), and density of the most abundant species did not detect any significant differences between substrates, except for D. sargus. It revealed instead significant differences among sites for C. chromis and Serranus cabrilla and among depth levels for C. chromis and Spicara maena. Furthermore, a significant interaction between these two factors for several species was found. Even though no marked differences between fish assemblages associated with the two substrates were observed, our findings suggest that further research on this topic would dramatically enhance our understanding of the fish distribution patterns in marine protected areas