Life cycle, growth and production of the polychaete Nereis diversicolor O. F. Müller in three lagoonal estuarine systems of the southwestern Portuguese coast (Odeceixe, Aljezur and Carrapateira)

During a period of 14 months (April/1993 to May/1994), monthly samples of Nereis diversicolor (adult and larvae) were taken in three coastal sites of the Portuguese southwest coast (Odeceixe, Aljezur and Carrapateira streams). The average of measured environmental parameters [temperature (°C), salinity (S%) and dissolved oxygen (O.D.)] obtained for each site was: 15.6°C, 31.7% and 8.6ppm for Odeceixe, 17.5°C, 29% and 8.8ppm for Aljezur, 19.5°C, 15% and 9.9ppm for Carrapateira. Densities of N. diversicolor obtained were: 15927, 8538 and 433 ind. m-2 for adult individuals and 1126, 957 and 337 ind. m-2 for the larva. Separation by cohorts using the BHATTACHARYA method allowed determination of the specific growth rate (d-1), the linear growth rate (mm/day) and the production by cohort. The population of Odeceixe presented an annual biomass of 85.65g m-2, an annual production of 12.83 g m-2 and a P/B index of 1.95. In Aljezur the annual biomass was 99.96 g m-2, the annual production 23.68 g m-2 and the P/B index 3.08. Carrapateira presented an annual biomass of 40.14 g m-2 , an annual production of 12.31 g m-2 and a P/B index of 4.0.