Analysis of food sources of Crassostrea gigas using high-throughput sequencing techniques

Abstract:

Filter-feeding bivalves have a wide range of food sources, including phytoplankton, organic detritus, and zooplankton, among others. In order to identify the food composition of filter-feeding bivalves, Crassostrea gigas cultured in Sanggou Bay, a typical northern large-scale mariculture bay, were used in the experiment. The eukaryotic composition of the stomach contents of C. gigas and of the ambient seawater column were analyzed using Illumina sequencing technology, in August 2019. Overall, 111,359 reads were optimized, and 239 operational taxonomic units were recognized by amplifying the 18S rDNA V4 loci sequences. The eukaryotes found in the stomach contents of C. gigas belonged to 34 phyla, with the majority belonging to Chlorophyta, Pyrrophyta, Streptophyta, Bacillariophyta, and Protozoa. As for the composition of the ambient seawater, the eukaryotes belonged to 37 phyla and they were mainly classified under Chlorophyta, Chordata, Arthropoda, Dinophyceae, and Bacillariophyta. The analysis showed that phytoplankton is the main food source for C. gigas, although Streptophyta and Protozoa accounted for a non-negligible portion of the total food content—10.43% and 4.11%, respectively. These results provide insights to further understand the feeding ecology of filter-feeding bivalves, as well as their role in material cycles and energy flow in mariculture ecosystems.