关键词: 网箱养殖, 底层水, 氮, 磷, 樟湖库湾, cage culture, bottom water, nitrogen, phosphorus, Zhanghu reservoir bay

Abstract: Based on the data from water environment in the cage culture area of Zhanghu reservoir bay surveyed in April, July and October 2018, the seasonal changes of nitrogen (N) and phosphorus (P) in the bottom water of cage culture area were analyzed and the state of eutrophication of water body was evaluated by using comprehensive nutrition state index. The results showed that there was no significant effect on the temperature, transparency (SD), CODMn and dissolved oxygen (DO) of the bottom water of cage culture in Zhanghu reservoir bay, while the culture area significantly increased pH in summer and chlorophyll a in spring, respectively. The concentrations of seasonal mean values of total nitrogen (TN), total phosphorus (TP) and total inorganic nitrogen (DIN) in the cage culture area of Zhanghu reservoir bay were higher than those in the control area, while there was no significant difference in the concentration of PO43--P between the cage culture area and the control area (P>0.05). The concentrations of TN, TP, ammonia nitrogen (NH4+-N), nitrate nitrogen (NO3--N) and nitrite nitrogen (NO2--N) in the cage culture area and the control area showed a seasonal trend of decreasing from spring to autumn. The concentration of PO43--P in summer was higher than that in other seasons in the cage culture area. The results of eutrophication evaluation showed that the water quality of the cage culture area was the heavy eutrophication level in spring and summer and the moderate eutrophication level in autumn, respectively.