The nematode fauna of the northern Adriatic offshore sediments: community structure and biodiversity

Abstract

          In order to provide a comparative source of data for local (Adriatic Sea) and regional (Mediterranean) biodiversity, as well as for future environmental quality assessments, the pattern of nematode fauna community structure at silty-sand offshore sediment was investigated. The qualitative and quantitative composition of nematofauna was studied at three northern Adriatic offshore sites associated with circalittoral zone and detritic bottom communities. The study involved the main population parameters (density, dominance, constancy) and community attributes (taxonomic composition, abundance, species richness, evenness, diversity, faunistic affinity). From 57 samples collected over a period of two years 12 350 Nematoda specimens were retrieved and subjected to spatial analysis. The results of multivariate analyses indicate high faunistic similarity, both from the qualitative (QS=68-76%) and quantitative aspects (QS=48-56%). The mutual intersection of k-dominance curves suggested the same trend of distribution of individuals per species at all sites investigated. In all, 168 free-living nematode species, comprising 101 genera and 29 families, were recorded. The area investigated is distinguished by considerable taxonomic diversity and respectable species richness (60% of total nematofauna species) in comparison to other Adriatic regions.