Marine exometabolites correlate with benthic fungal diversity and community structure in the South China Sea.

Marine exometabolites exert a substantial and dominant effect on interactions among marine benthic microorganisms. Nevertheless, the relationship between exometabolites and the community structure of benthic fungi remains unclear. In this study, we examined the abundance and diversity of fungal communities in various marine benthic habitats and elucidated their correlation with key elements, such as carbon and nitrogen, abiotic factors, such as pH, salinity, and depth, and marine exometabolites using various environmental metabolomic techniques. We found that the marine exometabolites primarily comprised organic acids and amino acids and their derivatives, which exhibited a broad negative and positive correlation with the Shannon of benthic fungal communities, respectively. Furthermore, the contribution of exometabolites to the changes in Shannon and benthic fungal community structure was higher than those of environmental factors, and organic acids exerted a highly significant impact on the fungal community structure. Key fungal taxa, such as IMPORTANCE: Research on the diversity and community structure of marine benthic fungi is limited. This study explores the relationships between these fungal communities and key elements (carbon and nitrogen), abiotic factors (pH, salinity, and depth), and exometabolites, with a focus on the role of marine exometabolites. The findings demonstrate that exometabolites, particularly organic acids, significantly influence the structure of benthic fungal communities. These results enhance our understanding of successional processes within these communities and clarify the interactions between benthic fungi and exometabolites, offering valuable insights into the formation of marine benthic fungal communities.