Phosphorus Exchange Characteristics at the Sediment-Water Interface and Microbial Driving Mechanisms in Aquaculture Ponds of Chinese Mitten Crab (Eriocheir sinensis)

• • DGT-measured labile P in upper sediment exceeded overlying water by a significant margin (exact values not provided) from late July to mid-August and in October, confirming sediment as a P source; this temporal pattern is critical for timing remediation efforts to prevent eutrophication. • • P diffusion flux at the sediment-water interface decreased from late July to mid-August and further by October, indicating that aquaculture duration modulates P release; this suggests that early intervention could mitigate P loading. • • Correlation between labile Fe and P, along with bacterial community analysis, implicates Fe-reducing and sulfate-reducing bacteria in P mobilization; this mechanistic insight enables targeted microbial management to reduce P release. • • Bacterial-driven organic P mineralization and inorganic P dissolution were identified as additional P release mechanisms, highlighting the need for integrated approaches addressing both Fe redox and organic matter degradation.