Evaluation et cartographie du stock du gasteropode trochide Phorcus articulatus (Lamarck, 1822) le long du littoral des iles Kerkennah (golfe de Gabes, Tunisie)

Abstract

This study is a first contribution to the assessment and cartography of the stock of Phorcus articulatus (Gastropod, Trochidae) along the coast of the Kerkennah Islands. Samples were collected using a quadrat and depending on radials perpendicular to the coastline. In total, 48 stations spread over 27 radials around the islands Gharbi and Chergui were seasonally sampled during 2009. Results show that the spatial distribution of the abundance and biomass of Phorcus articulatus is not uniform along the coast; it seems to be influenced by several environmental and anthropogenic factors. For example, the high abundances were recorded in areas naturally rich in trophic resources, and hydrodynamics also appears to play an important role in the distribution of size classes, since adults dominate the rocky area in the North-East where marine currents are stronger.