| The experimental survey done, in august 2005, in coastal marine zone (0 - 20 m) of Zarzis showed the existence of numerous species of shellfishes of which Tricolia speciosa, Smaragdia viridis, Nassarius incrassatus, Cerithium vulgatum and Gibbulla umbilicaris are the most important gasteropods and, Pinctada radiate and Donax trunculus the main bivalves. The biomasses estimation, based on the method of swept area, in the studied zone showed that P. radiate is the most abundant species with about 20 000 tones, followed by C. vulgatum (7 645 tones) and T. speciosa (more than 1 000 tones). The Donax trunculus biomass is very low with only 13 tones. Finally, the abundance indexes distribution cartography permitted us to note that it varies from one species to... |
