Distribuzione estiva del fitobentos e biomassa delle specie di interesse merceologico dello Stagnone. (Costa occidentale della Sicilia)

Abstract

En This survey hals been undertaken to evaluate the productive power of Stagnone near Marsala (western Sicilian coast) and it is a part of the project supported by the italian C.N.R. Thle aim of the research is to furnilsh a clear picturle of the viegetational associations in the summer anld evaluate thle productive capacity of the environmlent calculating the biomass of the species of colmmercial interest. Biomalsls values calculated as fresh-weight anld dry-wleight show that these populatiolnis potentially algree with an economic exploitation.The edaphilc factors condition the distribution of vegetation in the area stuldiled. Among the rizophytes the comunitiles prevalently of Cymodocea nodosa are more influenceld by the variations of edaphic factors and are Idisposed along the linels of penetration of the currents from the two mouths. In the more internal areas, where the hydric exchange is sicarce and the demmposing sediment of thle substrata is greater, Cymodocea nodosa gives way to a prlevalently Caulerpa prolifera comunities. The Posidonia oceanica comunities probabily very extentivle in the past, are rerduceld to a few colonies scattered in the central and southern part of thle Stagnone, while Lamprothamnion papulosum anld Chaetomorpha linum typical of enviromlents influences by fresh water is lilrniteid to a small area in the northen part the basin.Moreover the presence of a watershed in thle middle area of the basin, shows, Valonia aegagropila and aegagropila form Rytiphloea tinctoria, whereas Cystoseira barbata, typiical of the fenviroments with scarce water movemlents, shows the galenoiphil character, of this area. Particularly interesting is surnmler growth of Chonidria dasyphilla. Rytiphloea tinctoria anld Caulerpa prolif era are interesting frolm an industrial point of view an natural calomings and animal fooldstuffs due to their relmarkable biolmass.