Phosphorus Exchange Characteristics at the Sediment-Water Interface and Microbial Driving Mechanisms in Aquaculture Ponds of Chinese Mitten Crab (Eriocheir sinensis)
This study investigated phosphorus (P) exchange at the sediment-water interface and its microbial driving mechanisms in aquaculture ponds of Chinese mitten crab (Eriocheir sinensis). Using diffusive gradients in thin films (DGT), labile P concentrations in the upper sediment were significantly higher than in overlying water from late July to mid-August and in October, indicating sediment acts as a P source during these periods. The duration of aquaculture was a key factor; P diffusion flux declined from late July to mid-August and further decreased by October. Analyses of labile Fe, P-Fe correlations, and bacterial community composition and function suggested that dissimilatory Fe(III) reduction mediated by Fe-reducing bacteria and chemical Fe(III) reduction driven by sulfate-reducing bacteria metabolites were important mechanisms for P release. Additionally, bacterial-driven organic P mineralization and inorganic P dissolution contributed. The results indicate a high risk of P release from sediment to overlying water from late July to mid-August, potentially significantly affecting water P concentrations. Therefore, controlling sediment P release during this period is crucial.