Study on effect of PET water purification grid on ecological environment of pond culture

To study the effect of PET water purification grid on ecological environment of pond culture and Litopenaeus vannamei growth performance, we collected the pond water, phytoplankton and shrimp samples in Niu Tian Yang Breeding Base, Shantou from June to December in 2015 to compare various water-quality indices, phytoplankton diversity and shrimp growth index. The material of PET water purification grid, which was twisted by PET filament to form a linear attachment substrate, was divided into two groups:the test group and the control group (no biological water purification grid). The results show that during the culture period, the ammonia nitrogen, nitrate nitrogen and nitrite nitrogen concentrations in pool water at late experimental period were lower than those at early period, having decreased 68.25%, 42.71% and 83.51%, respectively. The phytoplankton survey results show that the average abundance of phytoplankton in the control pond and the test pond were 5.17×10⁸ cells · L^-1 and 3.62×10⁸ cells · L^-1, respectively; the Shannon-Wiener index and evenness index of the test pond were higher than those of the control pond by 8.70% and 6.45%, respectively. The shrimp culture experiment shows that the average body length and weight of L.vannamei in the test pond were significantly higher than those of the control pond by 6.13% and 16.67%, respectively(P < 0.01);per unit area of the feed amount in the test pond was significantly lower than that in the control pond by 15.44% (P < 0.01).