STRUCTURE OF THE TAXOCOENOSIS ANNELLIDA-MOLLUSCA IN THE MINGUEO AREA, GUAJIRA (COLOMBIAN CARIBBEAN).

Abstract

A punctual characterization of the soft-bottom macrobenthos was conducted on the continental shelf between Dibulla and Rio Palomino (Colombia). A net of 10 sample sites, 4 van Venn grabs per site, placed in deeps between 6 and 21.5 m, was sampled for this purpose. The results include 75% of the collected organisms, of which 69% were polychaeta and 6% mollusks. Analysis were performed at family level, in order to identify assemblages, a classification analysis between sample sites was performed and the groups there were confronted with the picture obtained from a non metric multidimensional scaling (NMDS). For each assemblage abundance, number of families, family dominance and diversity (K-dominance) were determined. By means of ABC curves the disturbance status of the assemblages was assessed. Finally, the pattern of distribution was related with water column depth and grain size of the sediments by means of the BIOENV technique. Results showed two assemblages called "Cossuridae" and "Lumbrineridae" on the basis of the polychaeta families that characterize them. The "Cossuridae" assemblage occurs in silt sediments offshore. It was the most diverse and showed the highest biomass levels. The Lumbrineridae assemblage occurs in fine sand sediments and shallow waters. The ABC curves analysis suggests that both assemblages are disturbed by natural causes since there is no human activity in the area. Water depth and fine sand were the environmental variables with the highest explanatory power in relation to the spatial distribution of the assemblages.