SELECTIVE FEEDING OF TWO BIVALVE SPECIES ON THE PHYTOPLANKTON COMMUNITY IN AN AQUACULTURE POND REVEALED BY HIGH-THROUGHPUT SEQUENCING.

Filtering bivalves consume microalgae throughout their life cycles, and for several decades, the selective feeding of bivalves on phytoplankton has been an active area of research in the fields of bivalve physiology and ecology. However, owing to the limitations of detection methods, there is comparatively little data available regarding the in situ food composition of suspension-feeding bivalves. In this study, conducted in December 2020, we used high-throughput sequencing of the 23S rRNA gene to characterize the phytoplankton community within the gut contents of the bivalves Meretrix meretrix and Scapharca subcrenata reared in the same aquaculture ponds. Phytoplankton from six phyla were identified in hepatopancreas samples obtained from M. meretrix, among which, Cyanophyta was found to be the predominant group, followed by Bacillariophyta. Seven phyla of phytoplankton were detected in the hepatopancreas samples obtained from S. subcrenata, among which, Cyanophyta and Chlorophyta were dominant. Ivlev’s electivity index was used to evaluate the feeding selectivity of the bivalves. The results indicated that M. meretrix showed a preferential selection for Cyanophyta and Bacillariophyta, whereas S. subcrenata preferentially selected Xanthophyta, Cyanophyta, and Chlorophyta. At the genus level, M. meretrix showed a preference for 12 genera, including Phormidium, Pleurocapsa, Skeletonema, Synechococcus, and Planktothricoides, whereas S. subcrenata showed a preferential selection for 16 genera, including Tetraselmis, Pleurocapsa, and Planktothricoides. [ABSTRACT FROM AUTHOR]