Influence of environmental variables on the growth and reproductive cycle of Crassostrea (Mollusca, Bivalvia) in Guaratuba Bay, Brazil

Abstract

The production of oysters in Guaratuba Bay, in the state of Paraná, Brazil, is still a mixed activity of mariculture and extractivism. The sustainable development of this production requires the monitoring of environmental, genetic, reproductive, and zootechnical variables. This study evaluated the importance of these variables on Crassostrea oyster production. Data were obtained between September 2009 and February 2011 from six evaluations: water quality, oyster larvae in plankton, capture of oyster spat by artificial collectors, molecular identification of collected spat and larvae, continuous evaluation of the reproductive maturity stage of adult oysters, and zootechnical performance achieved by experimental production. Temperature, dissolved oxygen, and water transparency were the environmental factors that had the most influence on the reproductive cycle (e.g. gonadal development and spat capture) and on the growth of the oyster. The highest rates for spat uptake were recorded in the summer, coinciding with the peak of sexual maturity of adults. The growth of the oysters, in terms of the weight of the meat, was related to the gonadal stage.