Distribution and abundance of the non-crustacean invertebrates at the continental shelf between the ports of Vilanova and Castellon, Western mediterranean

Trabajo final presentado por Maria V. Delahoz Aristizábal para el Máster en Biodiversidad de la Universitat de Barcelona (UB), realizado bajo la dirección del Dr. Manuel Ballesteros Vázquez de la Universitat de Barcelona (UB) y del Dr. Francisco Sardà Amills del Institut de Ciències del Mar (ICM-CSIC).-- 46 pages, 8 figures, 7 tables, 10 annexesEcological aspects of the non-crustacean benthic invertebrate community were studied in the continental shelf of the catalan sea during two seasons. Differences in abundance, biomass and diversity were assessed spatially between depth ranges (50-100 m, 100-200 m and 200-400 m), sediment types and geographical sites, and temporally between winter and summer. A total of 187 species from 9 phyla were recorded. Echinodermata (mainly crinoids) and Mollusca (mainly cephalopods) attained the highest abundances and biomasses, being crinoids the most conspicuous group of echinoderms, squids were the most conspicuous cephalopods and eventually ascidians made an important proportion of the invertebrate amounts. The community was dominated by a few abundant species that numerically made the highest proportion of most samples. The remaining species were comparatively scarce. The highest total of abundances and biomass were found during summer and on sandy substrate. The shallowest depth range was the most diverse, even though the Shannon diversity was generally low. Depth range was the most significant factor in the distribution of the community, establishing statistical differences across sample groupings, although the sediment type was regarded to play an important role in the distribution of the biomasses and abundances for the most important species. No exclusive species characterized the different environments, because most of them seemed to be broadly tolerant to environmental gradients, rather their variable abundances set the differences in contribution percentage to the different environments. Even though many species were rare, they accounted for a relatively high richness. In addition, fishing activity seem to be limiting the abundance of many of these species at a some extent, due to bycatch and decrease of habitat complexityPeer Reviewe