Meiobenthos of Sandy Beaches from the Gulf of Valencia (Western Mediterranean): Ecology of Interstitial Polychaetes

Abundance of meiofauna, particularly interstitial polychaetes, was estimated from quantitative samples collected at six sandy beaches in the Gulf of Valencia (Spain). Collecting stations included five stations without macrophytic cover and one station near Posidonia oceanica meadows. Multivariate ordination procedures were used to identify physicochemical and biotic factors that might be predictors of microhabitats used by interstitial polychaetes. Four species of polychaetes were found in sandy beaches without macrophytic cover: Hesionides gohari, Hesionura coineaui, Saccocirrus parvus, and S. papillocercus. The most abundant species was H. gohari which was found throughout the infralittoral zone; whereas S. parvus was characteristic of the mesolittoral zone. Principal component analysis using the variables mean grain size, porosity, organic contents and meiofauna abundance, showed that 66% of the variance could be explained by the two main components, We identified component I as the vertical zonation, and component II as beach exposure. The polychaete fauna of the station located near Posidonia oceanica meadows had the highest species diversity with predominance of members of the family Syllidae. However, some species of genus Protodrilus, were the most prevalent reaching four times the abundances recorded for the remaining polychaete species.