Effect of salinity on the metamorphosis, settlement, and post-larval stage of the mangrove oyster, Crassostrea rhizophorae (Guilding, 1828).

Abstract

This study assessed the effect of salinity on the development of the mangrove oyster, Crassostrea rhizophorae, during the pediveliger, metamorphosis, and post-larvae stages, with individuals retained on ≥ 345 µm and ≥ 700 µm meshes. The experiment followed a completely randomized design with five salinity treatments (15, 20, 25, 30, and 35) and four replicates, conducted in three phases: (1) pediveliger and metamorphosis (7-day duration); (2) post-larvae retained on a ≥ 345 and < 500 µm mesh (16-day duration); and (3) post-larvae retained on ≥ 700 and < 1,000 µm meshes (21-day duration). Experimental units consisted of a downwelling system using screen-bottomed PVC cylinders. Oysters were fed Isochrysis galbana and Chaetoceros sp., with feed concentrations adjusted for each developmental stage. Yield (percentage of the initial stock retained alive on the final mesh) and survival (total live post-larvae relative to the initial stocked number) were determined by sieving. A salinity of 30 produced the highest yield during the pediveliger and metamorphosis phase (31.94% ± 4.53%), while salinities between 15 and 30 favored survival for post-larvae in the ≥ 345 µm size class. No significant differences in survival or yield were detected during the final post-larval stage. Overall, a salinity of 30 is recommended for the final larval and the post-larval stage for C. rhizophorae.