Gonadal maturation, conditioning, and spawning in the laboratory andmaturation cycle in the wild of Cerastoderma glaucum Bruguiere

摘要

Cerastoderma glaucum Bruguiere has a wide geographical distribution in Europe, from the Mediterranean to the North Atlantic and the Baltic Sea. This cockle is found mainly in coastal embayments and lagoons on muddy, soft bottom. The different reproductive behavior of cockles is related to latitude. In Lesina Lagoon, cockles initiate gametogenesis several times per year; this has been confirmed in laboratory tests where cockles are provided ample Tahitian Isochrysis aff. galbana (clone T-ISO). In the laboratory, cockle biomass (density 400-800 g/m(2)) releases viable gametes all year in a relatively wide range of temperatures (9-24 degrees C). During 12 months of repeated spawning, cockles released a mean of 68,100 eggs/cockle, with an average of 1.13 spawning per week. Because of its high genetic variability, which accounts for its adaptability and ease of spreading in environments with striking changes of physical and chemical aquatic conditions, cockles may have an excellent potential for mariculture application. In addition cockles may play an important ecological role in reducing the particulate organic load of eutrophic lagoons and embayments with a wide range type of salinity and thermal characteristics.