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Abstract: To investigate the environmental microbiota characteristics of different net cage aquaculture types during the ice-melting period, we conducted experiments across three aquaculture systems in Dalian, Liaoning Province: the traditional pond net cages in Pulandian, permeable pond net cages in Wafangdian, and offshore net cages in Zhuanghe. Environmental factors of the three types of net cage aquaculture were monitored. 16S rRNA sequencing technology was employed to investigate bacterial community structure and functions in both cage-attached substances and water samples under these aquaculture modes during the ice-melting period. The results showed that Bacteroidota, Verrucomicrobiota, and Proteobacteria were the dominant bacterial phyla in water and attached substance samples during the ice-melting period. Unique bacterial communities were identified in specific environments. Planctomycetota and Bacteroidota were characteristic of Pulandian traditional pond net cages. Patescibacteria dominated in Wafangdian permeable pond net cages. Verrucomicrobiota was specifically enriched in Zhuanghe offshore net cages. KEGG pathway analysis revealed significant differences in metabolic pathways among different net cage types (P<0.05), particularly in amino acid metabolism, carbohydrate metabolism, and lipid metabolism. This study demonstrates distinct structural and functional variations in environmental microbiota across different net cage aquaculture systems during the ice-melting period, providing theoretical references for disease prevention in sea cucumber aquaculture and microbial community regulation in net cage environments.

Key words: Apostichopus japonicus, ice-melting period, net cage aquaculture, microbial community structure, high-throughput sequencing