Effect of bacterial community succession on environmental factors during litter decomposition of the seaweed Gracilaria lemaneiformis

In large-scale seaweed farming, an understanding of the decomposition process plays a pivotal role in optimizing cultivation practices by considering the influence of the bacterial community. Therefore, we assessed the bacterial community structure and its influence on environmental factors during Gracilaria lemaneiformis decomposition, utilizing both microcosms and in-situ simulations. The decomposition rates in the microcosms and in situ simulations reached 79 % within 180 days and 81 % within 50 days, respectively In the microcosms, the dissolved oxygen content decreased from 5.3 to 0.4 mg/L, while the concentrations of total organic carbon, nitrogen, and phosphorus in the water increased by 165 %, 1636 %, and 2360 %, respectively. The common dominant bacteria included Proteobacteria, Planctomycetes, Firmicutes, Bacteroidetes, and Spirochaetae. Planctomycetes and Firmicutes were positively correlated with the total organic carbon, nitrogen, and phosphorus concentrations. Planctomycetes species played significant roles during the decomposition process. The overall findings of this study could inform more sustainable seaweed cultivation practices.