Influences of media provisioning on phosphorus forms in surface sediments and benthos baits cultivation effects

ObjectiveInfluences of media provisioning on phosphorus forms in surface sediments and benthos baits cultivation effects were studied to provide reference for application of new media in ecological pond culture. MethodIn the experiment,different amounts of culture media were buried in ponds,which were 4.5×103 (treatment 1)、1.35×104(treat-ment 2)、6.75×104(treatment 3)kg/ha,control group did not deliver culture medium, and each group set two repeats. In spring, summer and autumn, surface sediment was collected twice each quarter for measuring phosphorus of different forms. At the end of each month, benthos baits were collected to measure the biomass.ResultDensity of Tubificidae increased with the increase of culture medium amount in four experimental treatments, the order of biomass of Chironomid larvae was:treatment 2(12.82 g/m2)>treatment 1(10.77 g/m2)>treatment 3(10.02 g/m2)>control(8.91 g/m2). Biomass in treatment 1, 2 and 3 were 43.90%, 20.85%, and 12.50%higher than that in control respectively. The contents of total phosphorus(TP), inorganic phosphorus (IP), calcium-bound phosphorus (Ca-P), aluminum-bound phosphorus (Al-P), and loosely sorbed phosphorus(Labile-P) were all represented as follows: treatment 3>treatment 2>treatment 1>control, which meant these indexes were positively correlated with media amount. The seasonal variation of Labile-P content in four treatments was:autumn>spring>summer, and the seasonal variations of Fe-P, Al-P and Ca-P was spring>summer>autumn. The average contents of Labile-P and Fe-P were 27.00%and 31.00%higher than those in control respectively. ConclusionMedia pro-visioning in aquaculture ponds can effectively improve the biomass of benthos baits and increase Labile-P and Fe-P con-tents of phosphorus of different forms in surface sediment. Rising Fe-P content is benefical for culture of Chironomid lar-vae, then can provide natural baits for pond culture for shrimp and crab.