engleski

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

In order to provide the comparative source of data for local (Adriatic Sea) and regional (Mediterranean) biodiversity, as well as for future environmental quality assessments, the pattern of nematofauna community structure at the silty-sand offshore sediment was investigated. The qualitative and quantitative composition of nematofauna was studied at three northern Adriatic offshore sites (SJ107: 13o19.0'E, 45o26.1'N ; SJ 005: 13o08.0'E, 45o18.4'N ; SJ 007: 13o16.0'E, 45o17.1'N) with similar environmental features (depth, sediment type, salinity, temperature) and similar macrobenthic composition. 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 during two years 12350 nematoda specimens were picked out and subjected to spatial analysis. The results of multivariate analyses indicate high faunistic similarity, both from qualitative (QS = 68-76 %) and quantitative aspects (QS = 48-56 %). Mutual intersection of k-dominance curves suggested the same trend of distribution of individuals per species at all stations investigated. In all, 168 free-living nematode species, comprised in 101 genera and 29 families were recorded. The structure of nematofauna at silty-sand offshore sediment was determined by distinctive dominance of four families (Chromadoridae, Comesomatidae, Cyatholaimidae and Linhomoeidae) and ten species (Ptycholaimellus ponticus, Terschellingia longicaudata, Dorylaimopsis mediterranea, Marilinya complexa, Sabatieria ornata, S. granulosa, Spilophorella paradoxa, Setosabatieria hilarula, Rhabdodemania mediterranea and Axonolaimus setosus), outstanding position of 5-6 species (D $ 5%) per site, and by rather high species diversity (S = 99-126 species/site, H' = 5, 1-533 bits/ind). The area investigated is distinguished by considerable taxonomic diversity, and respectable species richness (60% of total nematofauna species) in comparison to other Adriatic regions.-

nematodes; community structure; offshore sediments; Northern Adriatic

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