Bioavailability of organic phosphorus in an eutrophic lake: Insights from an in-situ experiment

•Bioavailability of in-situ organic phosphorus was determined in a eutrophic lake.•Soluble reactive phosphorus showed a negative relationship with organic phosphorus.•Large amounts of sedimentary organic phosphorus were transformed into SRP.•Hydrophytes acted as a “pump” in the phosphorus biogeochemical cycle.