Meso-scale variability of coastal suprabenthic communities in the southern Tyrrhenian Sea (western Mediterranean)

• Published in: Estuarine, coastal and shelf science coastal and shelf science, 2011-02, Vol.91 (3), p.351-360
• Main Authors: Fanelli, E., Cartes, J.E., Badalamenti, F., D’Anna, G., Pipitone, C., Azzurro, E., Rumolo, P., Sprovieri, M.
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; assemblage structure; Biological and medical sciences; Brackish; Brackish water ecosystems; Coastal; Communities; Correlation; diversity; Feeders; Foods; Fundamental and applied biological sciences. Psychology; Gulfs; Sea water ecosystems; spatial variability; stable isotopes; suprabenthos; Synecology; trawl-ban; Trawling; Trawls
• ISSN: 0272-7714; 1096-0015
• DOI: 10.1016/j.ecss.2010.10.026

Meso-scale spatial variability of coastal suprabenthic communities inhabiting muddy bottoms at 50–80 m depth in three gulfs of northern Sicily (Western Mediterranean) was here investigated. Although similar as concerns the hydrological and oceanographic conditions, the three areas, that encompass a large portion of the continental shelf (135 km), are characterized by different geo-morphological features. In addition, they are subjected to different trawl fishery pressures. The Gulf of Castellammare is a semi-enclosed bay, where the trawling activity has been banned since 1990. The Gulf of Termini Imerese and the Gulf of Sant’Agata are open areas, subjected to high trawl fishing intensity. In terms of density, gammarid amphipods showed differences among the three gulfs; in terms of biomass, cumaceans and amphipods were more abundant in the Gulf of Castellammare than in the other two areas. Multivariate analyses provided evidence for separation of suprabenthic assemblages between the Gulf of Castellammare and the other two gulfs. The Gulf of Castellammare seemed to host the most diversified and stable community according to α- and β-diversity indices. In the same way the low value of δ 13C vs. δ 15N correlation found in the gulf of Castellammare, which evidences the occurrence of several food sources, supports the idea of a higher stability in the semi-enclosed, trawl-ban area. In the other two areas δ 13C vs. δ 15N correlations were high, suggesting the existence of a pelagic source sustaining the suprabenthic communities. This is also confirmed by the lower δ 13C concentrations found in suprabenthic species. Taking into account the homogeneous oceanographic conditions among gulfs, other factors, such as geo-morphology and trawling pressure should be involved in the observed differences among the three areas in terms of assemblage structure, diversity, and trophodynamics of suprabenthic communities. ► Trawl-ban area (GCAST) showed higher a-diversity, but lower b-diversity. ► More deposit feeders in GCAST, suspension feeders/grazers dominated in fished gulfs. ► Several food sources occurred in GCAST, supporting the idea a higher stability. ► High d 13C-d 15N correlations in fished areas suggested the existence of pelagic source. ► Geo-morphology or trawling was invoked as possible cause of the observed differences.