Annual Variation of Water Quality in Aquaculture Ponds for Apostichopus japonicus

By measuring water temperature, salinity, pH, dissolved oxygen, nitrite and ammonia nitrogen, the annual variation regularity of water quality in the aquaculture ponds for sea cucumbers Apostichopus japonicus in Dalian were studied. Results showed that the physicochemical indicators kept changing in the year, and the various ranges of water temperature, salinity, pH, dissolved oxygen, nitrite, and ammonia nitrogen were 6.38-27.27℃, 29.20‰-33.78‰, 7.86-8.38, 5.19-13.36 mg/L, 0.003 7-0.009 0 mg/L and 0.017 1-0.090 8 mg/L, respectively. Analysis indicated that there was an extremely significant negative correlation between water temperature and dissolved oxygen (P < 0.01), an extremely significant positive correlation between water temperature and ammonia nitrogen (P < 0.01), a significant negative correlation between salinity and nitrite (P < 0.05), a significant negative correlation between dissolved oxygen and nitrite (P < 0.05), and an extremely significant negative correlation between dissolved oxygen and ammonia nitrogen (P < 0.01) in the aquaculture ponds for sea cucumber in Dalian. Research showed that the water quality of aquaculture ponds kept fluctuating all the time during the tested period, there were complicated and close relationships among physicochemical indicators, and a slight variation of external factors would bring consecutive reactions to different indicators in the water quality of aquaculture ponds. A reference for the production and management of sea cucumbers could be provided from the results.