Benthivorous fish cause a shift from a clear water state established by combining​ phosphorus immobilization and submerged macrophytes to a turbid state: A mesocosm study

Both chemical phosphorus (P) immobilization and submerged macrophytes are widely used in lake restorations to reduce internal loading. Their combined effects seem much stronger than alone. However, benthivorous fish populations recover fast they may thus counteract the restoration effects. We conducted a mesocosm experiment with three densities of crucian carp (Carassius auratus gibelio) study on lanthanum (La) modified bentonite macrophyte Vallisneria denseserrulata restoration: control (fish-free), low-density (45 g m−2) high-density (83 m−2). Crucian increased concentrations total phosphorus, nitrogen, suspended solids, chlorophyll deteriorated light climate water column compared controls. The porewater soluble reactive deep sediment were two times higher treatment group treatment. mobile (mainly NaOH-OP) 0–2 cm sediment, likely due dilution La surface as caused by accelerated downward transportation La, at same time La-bound P (part HCl-P fraction) was mixed deeper into increasing density. In mesocosms, plant biomass density reduced 37% 51%, respectively, which is another possible mechanism for quality deterioration. conclude that it important when conducting combining macrophytes.