Study of weight gain and reproduction in the Perna perna mussel using a standard animal

This study aims to establish a link between weight variation of the brown mussel Perna perna, condition index and the environmental parameters. In order to eliminate the effect of growth on the weight variation, a standard sized animal of about 60 mm, was used. Random sampling of mussels and seawater was conducted once a month, from two sites in the Gulf of Annaba (Algeria), over an annual cycle. Growth parameters were determined by reference to shell length, fresh and dry mass tissue weight, as well as shell and total weight. Temperature, dissolved oxygen, salinity, chlorophyll a and suspended matter were recorded at each site. The results show that, the CI variation in the SI is a function of weight, which is itself a function of the sexual stage as well as the availability of food (especially chlorophyll-a and suspended matter). The period of the maximum of gain weight corresponds with the increases in the condition index and was associated with high concentrations of chlorophyll-a and suspended matter, recorded during the spring period. This is supported by statistical analysis showing a significant correlation. Perna perna has two spawning periods, one in the autumn and one in winter. The knowledge of the reproductive cycle and environmental parameters that could influence them may constitute a basic data, necessary not only for any commercial exploitation of this mussel species, but for its use as bio-monitoring as well. Such monitoring assures a qualitative analysis of shellfish aquaculture products and helps to choose mussel cultivation sites.