Recruitment of oyster in artificial collectors on the Amazon macrotidal mangrove coast

Abstract

The purpose of this study was to determine the moment of the year for the oyster recruitment and define the type of collector and environmental conditions that maximize recruitment. Collections were conducted, during 12 months, on Amazon Macrotidal Mangrove at two different sites: raft (point I) and mangrove (point II). In each location three types of collectors were used (1) transparent PET bottles, (2) green PET bottles, and (3) PVC sheets, each with three replicates. Spats were counted and measured at 45-day intervals, while the environmental data were measured every two weeks. Identification of oyster species occurred by genetic testing (multiplex PCR) by randomly selecting individuals by sampling. Results indicated spat capturing was significantly influenced by the collector type, location and period of collection (P<0.05, MANOVA) with significantly higher recruitment in the PVC collector (P<0.05, Tukey test). Oyster recruitment occurred throughout the year, suggesting that these individuals reproduce during all months; however, months with less rain and greater salinity were the best for spat collection, while the rainy period with lower salinity proved to be the best for individuals growth. The location in interaction with the environmental variables, mainly salinity, has a significant effect on the recruitment rate of spat and on their size, so that point II (mangrove) had the best results for recruitment and point I (raft) provided the spats of the largest size. Genetic identification verified two native oysters species (Crassostrea gasar and Crassostrea rhizophorae) in both points (I and II).