Estado reproductivo de la ostra del Pacífico Crassostrea gigas (Thunberg 1793) bajo condiciones de cultivo suspendido en Bahía Caráquez, Provincia de Manabí, Ecuador: influencia de los factores ambientales

Abstract

The oyster reproductive cycle of the Pacific Crassostrea gigas (Thunberg, 1793) was evaluated under suspended culture conditions in Bahía de Caráquez, Manabí province, Ecuador and the influence of environmental factors on reproduction. For this, in the period April - November, organisms were taken monthly from a suspended crop established at the Amistad Puelle Dock, in Bahía de Caráquez. These bodies were used for making cuts his tologists function of determining reproductive variables sex ratio and identification of reproductive stages. In order to determine the influence of the environmental factors of reproduction, the temperature was determined, the oxygen, salinity and phytoplankton biomass (chlorophyll a) in the cultivation area, to be correlated with the reproductive stages. The first s months were dominated by males and undifferentiated organisms, stabilizing at a ratio of female-male 1: 2.3 from July when the organisms obtained about 40 mm, suggesting an extended protandría. Although there was presence of hermaphrodite organisms, their percentage was <2%. Organisms with sizes greater than 40 mm, they showed, in every month, different stages of reproductive development, generally observing organisms in spawning, although always in a proportion <40%, suggesting a characteristic of continuous reproduction characteristic of tropical water organisms. The environmental variability observed in the different parameters determined is classic of marine estuaries in the dry season, where the changes are particularly based on the tidal regime. There was no obvious correlativity of the reproductive activity (maturation and spawning phases) with the variability of the environmental factors, so it is not possible to establish a modulation of the reproduction by environmental factors, and it is postulated that the modulation of the reproduction would be associated rather by endogenous factors. In general, the levels observed do not seem to have influence on the development of Crassostrea gigas, rather they are within the optimal ranges of their development exposed for cultivation by FAO.