Structure of Seawater and Sediment Bacterial Community and Its Correlation with Environmental Factors in Fujian Dongwuyang Bay

Abstract

The Dongwuyang Bay of Fujian Province is the core production area for sea cucumber culture in South China; however, research on the environmental status and bacterial community structure in this area is still limited. In this study, we investigated and evaluated the seawater quality in January, which is the peak culture period for sea cucumber in this area, and analyzed the diversity and differential characteristics of seawater and sediment bacterial community structure using the high-throughput sequencing method and analyzed the correlation between environmental factors and bacterial community structure. The following results were obtained: The Makeng eutrophication index reached 21.60, which indicated that this area was experiencing serious eutrophication. Dong´an and Leijiang were experiencing severe eutrophication, and only the Shawan sea area was experiencing moderate eutrophication. The organic pollution assessment showed that Dong´an and Shawan had light organic pollution, while Makeng and Leijiang had moderate organic pollution. A total of 1 520 OTUs were obtained via high-throughput sequencing, belonging to 28 phyla, 57 orders, 163 families, 322 families, and 581 genera. The diversity analysis revealed that the level of bacterial community diversity in the sediment of each region was significantly higher than that of the corresponding seawater diversity and presented stronger spatial heterogeneity. The diversity and abundance in Shawan were the highest. The results of the principal coordinate analysis and similarity analysis showed that there were significant differences in the bacterial community composition between sediment and seawater. The cluster analysis revealed that the cluster was influenced by water exchange and site location. Vibrionaceae, a family with potential pathogenicity, was one of the dominant species in all seawater and sediment samples. LEFSe (line discriminant analysis effect size) analysis of seawater column samples and sediment samples screened 74 specific OTUs (operational taxonomic units) of bacteria at different taxonomic levels. Prediction of gene function and COG (clusters of orthologous groups of proteins) classification statistics showed significant differences in 12 metabolic pathways between seawater and sediment samples (P < 0.05). LEFSe analysis of bacterial community structure from four sites screened 30 specific OTUs at different taxonomic levels. The RDA (redundancy analysis) of the seawater bacterial community structure with environmental factors revealed that temperature, dissolved oxygen, and chlorophyll-a concentration were the major environmental factors affecting the structure in the four sites. Related studies should provide basic data and scientific reference for the management of sea cucumber culture in Fujian Province.

Keywords

• dongwuyang bay
• sea cucumber cage culture
• environmental evaluation
• bacterial community structure analysis