Role of aquatic fungal species in decomposition and nutrient cycling in freshwater ecosystems

Abstract

Fungi in freshwater ecosystems help decompose organic matter and recycle nutrients. Hyphomycetes and Chytrid fungi assist in the conversion and decomposition of complex plant polymers. Still, the structure, functions, and diversity of these communities and the aquatic fungi in general remain poorly understood, particularly in relation to climate and hydrology. Integrated metagenomics–enzymatic activity assessment aims to identify which of the principal aquatic fungal taxa decompose leaf litter and regulate nutrient flow. Water and sediment samples were collected from freshwater bodies to analyze fungal community composition through high-throughput ITS sequencing. Fungal decomposition was assessed using laccase, cellulase, and phosphatase assays, and for nutrient analysis, the results were assessed for biogeochemical cycling using the C: N:P ratio and total dissolved organic matter. The dominant decomposers were Ascomycota and Chytridiomycota, and the results showed strong correlations between enzymatic activity and nutrient release. Changes in fungal diversity and nutrient transformation were primarily anthropogenic and seasonal. This research highlights the functional role of aquatic fungi in energy flow and nutrient decomposition in freshwater systems and the importance of including them in the nutrient and health assessment of freshwater ecosystems.