Effect of fish cage culture on water environment in Xiangshan Harbor

Abstract:

On the basis of investigation data observed at the fish cage culture area for 6 cruises in 2010, variation characteristics of DO, pH and nutrients in fish cage culture areas of Xiangshan Harbor were analyzed. The result indicated that the DO (dissolved oxygen) and pH complied with the Grade Ⅱ in “Seawater Quality Standard”(GB 3097—1997). The range concentration of inorganic nitrogen was 0.726-1.133mg/L, the concentration of NO₃-N accounted for 74.83% of DIN and was the main form of inorganic nitrogen in the fish cage culture area. The range concentration of inorganic phosphorus and silicate were 0.043-0.082 mg/L and 0.794-1.357 mg/L, respectively. The concentration of inorganic nitrogen and inorganic phosphorus were too high to satisfy the Grade Ⅱ of “Seawater Quality Standard”(GB 3097—1997). The ratio of N to P was 34.02, so N was relative surplus. According to the value of eutrophication index (E) and organic pollution index (A), the seawater was in eutrophication state, and the organic pollution was quite serious.