Spatio‐temporal variability in fish assemblages associated with coralligenous formations in south eastern Apulia (SE Italy)

Abstract

Fish assemblages associated with ‘coralligenous formations’ in SE Apulia (Lower Adriatic and Ionian Seas, SE Italy) were studied by visual census to test for differences through time and over dif ferent spatial scales (i.e., among locations 3–4 km from each oth er, and among sites within locations 200–400 metres apart from each other). Thirty‐two fish species were recorded, with sparids (eight species), labrids (seven) and serranids (five) being the fam ilies with most species. Fish assemblages were numerically domi nated by Chromis chromis, Boops boops, and Coris julis. Multivari‐ate analyses indicated significant differences in the structure of fish assemblages among times and locations (with C. chromis and C. julis mostly contributing to the observed dissimilarities), while sites within locations did not differ significantly. Temporal pat terns of species richness differed both among locations and among sites within locations. Total fish abundance displayed dif ferent temporal trends at the smallest spatial scale examined (i.e., among sites within locations), whereas patterns over time in fish abundance without the contribution of gregarious species differed among locations only. The results show, therefore, that fish as semblages from coralligenous formations in SE Apulia might vary in time in spite of a fairly stable benthic environment. Temporal changes of the most important univariate variables (e.g., species richness) might thus differ among sites, locations or both. Factors acting at different spatial scales (e.g., habitat complexity, substrate slope) and through time (e.g., feeding displacements), probably involved in the variability of spatio‐temporal patterns of fish as semblages, are discussed.