Fish community associated with Halophila stipulcea meadow in the Mediterranean sea

The fish fauna of a Halopila stipulacea meadow was studied in the Peninsula of Maddalena (Eastern Sicil y, Italy; Mediterranean). Visual censuses were conducted every three months from October 1998 to July 1999 and from October 2003 to July 2004. Environmental variables for water temperature, salinity and seagrass shoot density were collected on each sampling occasion. A total of 30 fish species from eight families were recorded. Three labrids and sparids, two serranids and one mullid were detected with high frequency of occurrence (> 75%), while Sarpa salpa, Coris j u l i s , Oblada melanura, Mullus surmuletus and Thalassoma pavo were the most abundant species. Diversity index and density values displayed a distinct seasonal pattern with highest values occurring in summer and autumn. These community variables were positively related to water temperature, but not to salinity and shoot density. Differences were also found in the relationships between the relative abundances of two species (Oblada melanura and Serranus cabrilla) and water temperature. Multivariate analysis revealed variation in species composition of the fish community throughout the year. The data show that the fish fauna of the Halophila stipulacea meadow of the Peninsula of Maddalena was characterised by a seasonal variation of the community structure, probably mainly influenced by the fluctuations of environmental variables. T h e presence of small and juvenile fishes of a number of species emphasises the potentially important function of nursery exerted by such seagrass systems during the first phases of the life history of several species.