Abstract
Oyster feeding biology is strongly influenced by ecological and biological factors, and understanding these interactions is critical for successful aquaculture development. Accordingly, an extensive study was conducted using an integrated multivariate approach to explore the feeding biology of the oyster Crassostrea madrasensis (collected from the southeast coastal regions of the Bay of Bengal in Bangladesh), by examining the interrelationship between ecological factors, seasonal plankton dynamics, biometric traits, a nd plankton ingestion patterns. Field data were collected monthly from July 2023 to June 2024 at two sites in Cox’s Bazar, Bangladesh (Maheshkhali and Khurushkul). Environmental parameters (temperature, salinity, pH, and dissolved oxygen) were recorded in situ, and plankton samples from both water and oyster gut contents were analyzed using a Sedgewick Rafter counting cell and identified to the genus level using microscopy. A total of 53 planktonic genera (47 phytoplankton , 6 zooplankton) were identified in the gastrointestinal tract of oysters in the present study. Amphidinium (17.5%) was the most ingested genus, followed by Skeletonema (15.1%), Coscinodiscus (12.0%), and Cyclotella (10.8%). Other major genera found in oysters’ gastrointestinal tracts were Lioloma , Thalassionema , Pleurosigma, Pseudo-nitzschia , Anabaena, Oscillatoria, and Copepoda . Multivariate and correlation analyses revealed that seasonal variation and environmental factors significantly influenced plankton composition in both water and oyster gut contents. Principal component analysis (PCA) showed that the first two components explained 50.2% of the variation in gut plankton composition, primarily driven by seasonality. Cluster analysis indicated peak plankton ingestion during August, October–December, and February. Oysters ingested large amounts of Coscinodiscophyceae in November, Fragilariophyceae in June, Bacillariophyceae in August, Dinophyceae in February, and zooplankton in April. These findings enhance our understanding of oyster feeding behavior in relation to seasonal water quality, plankton availability, and biometric traits, offering valuable insights for oyster aquaculture expansion and blue economy development in Bangladesh.
Keywords: Crassostrea madrasensis , selective feeding behavior, plankton assemblage, environmental drivers, seasonal variation, multivariate ecological analysis, coastal aquaculture management.