Description of parameters of the population dynamics of polar bivalve communities, first year: growth and reproductive cycle of the dominant Greenland cockles (Serripes groenlandicus)
Greenland cockles (Serripes groenlandicus)
Greenland cockles (Serripes groenlandicus) dominate the soft bottom communities. Therefore we chose this clam for detailed studies of one organism having presumably a dominant affect on soft sediment succession. It is planned that 30 individuals will be sampled monthly over a years' period. Since there is no diving team available throughout the year bivalves will be sampled, marked with the help of two parallel sanding discs fixed to a handhold electric driller and released in round cages (app. 40 cm in diameter). These cages will be produced in the AWI workshop in advance and installed under the sediment surface in front of the sheet piling of the harbour, at 8 meter depth that they will not interfere with the docking ships. Cages will be fixed to a rope, which will be installed on the ground, turned around on a clamp at the lower end of the sheet piling and fixed on the surface (details are currently discussed with Øystein Blia, Kings Bay). Each month one cage will be lifted and clams fixed in formalin for further investigations (growth, reproductive cycle). At the laboratory in Bremerhaven, cockles will be measured to the lower mm and growth in-crements calculated. These parameters will be used to establish a von Bertalanffy growth function. Additionally acetat peels will be produced. The results will be needed for further investigations and age estimates from free living cockles for future campaigns. The reproduc-tive cycle of Serripes groenlandicus will be analysed using histological methods.
Universidad de Córdoba, Argentina