College of Oceanography and Ecological Science, Shanghai Ocean University, Shanghai, China; State Environmental Protection Key Laboratory of Coastal Ecosystem, National Marine Environmental Monitoring Center, Dalian, China.
Groundwater Provincial Engineering Research Center for Urban Water Recycling and Environmental Safety, Shenzhen International Graduate School, Tsinghua University, Shenzhen, China.
Sci Total Environ. 2024 Apr 10;920:170511. doi: 10.1016/j.scitotenv.2024.170511. Epub 2024 Feb 2.
The influence of macroalgae cultivation on aquaculture carbon sinks is significant, with microbial carbon (C) pumps contributing to a stable inert dissolved carbon pool in this context. Concurrently, dissolved organic matter (DOM) exchange at the marine sediment-water interface profoundly affects global ecosystem element cycling. However, the interactions between DOM and bacterial communities at the sediment-water interface in kelp cultivation areas, especially regarding microbial function prediction, have not been fully explored. This study analyzed the DOM characteristics, environmental factors, and bacterial community structure in the Tahewan kelp--Saccharina japonica cultivated area and compared them with those in non-cultivated areas. The results indicated significantly higher dissolved organic carbon (DOC) concentrations in the kelp culture area, particularly in surface seawater and overlying water. The dominant bacterial phyla in both regions included Pseudomonadota, Actinomycetota, and Bacteroidota in both regions, while Desulfobacterota was more prevalent in the sediment environment of the cultivated region. Parallel factor analysis (EEM-PARAFAC) was used to identify DOM components, among which component C2 (a microbial humic-like substance DOM) was highly resistant to microbial degradation. We infer that C2 has similar properties to recalcitrant dissolved organic matter (RDOM). Analysis of the predicted functional genes based on 16S rRNA gene data showed that methanol oxidation, methylotrophy, and methanotrophy were significant in the bottom seawater of the cultivation area. The carbon (C), nitrogen (N), and sulfur (S) cycle functional genes in the sediment environment of the kelp cultivation area were more active than those in other areas, especially in which sulfate reduction and denitrification were the two main processes. Furthermore, a DOM priming effect was identified in the cultivated sediment environment, where kelp-released labile dissolved organic matter (LDOM) stimulates rapid degradation of the original RDOM, potentially enhancing C sequestration.
大型藻类养殖对水产养殖碳汇的影响显著，微生物碳（C）泵在这种情况下有助于形成稳定的惰性溶解碳库。同时，海洋沉积物-水界面的溶解有机物质（DOM）交换深刻影响着全球生态系统元素循环。然而，在海带养殖区，DOM 与细菌群落之间的相互作用，特别是关于微生物功能的预测，尚未得到充分探索。本研究分析了塔湾海带-日本裙带菜养殖区和非养殖区的 DOM 特征、环境因素和细菌群落结构。结果表明，养殖区海水中溶解有机碳（DOC）浓度明显较高，特别是在表层海水和上覆水中。两个区域的优势细菌门包括 Pseudomonadota、Actinomycetota 和 Bacteroidota，而 Desulfobacterota 在养殖区沉积物环境中更为普遍。平行因子分析（EEM-PARAFAC）用于鉴定 DOM 成分，其中成分 C2（微生物腐殖质样物质 DOM）对微生物降解具有很强的抗性。我们推断 C2 与难降解溶解有机物质（RDOM）具有相似的性质。基于 16S rRNA 基因数据对预测功能基因的分析表明，养殖区底层海水中甲醇氧化、甲基营养型和甲烷营养型作用显著。养殖区沉积物环境中的碳（C）、氮（N）和硫（S）循环功能基因比其他区域更为活跃，特别是硫酸盐还原和反硝化是两个主要过程。此外，在养殖沉积物环境中还发现了 DOM 激发效应，海带释放的可利用溶解有机物质（LDOM）刺激了原始 RDOM 的快速降解，可能增强了碳固存。
