Abstract:
From October 2020 to April 2021, the fish-shrimp-shellfish integrated multi-trophic mariculture ponds in Fotan Bay reclamation area of Zhangpu County were investigated. The results showed that the water temperature of each pond varied from 17.8 ℃ to 25.5 ℃ and salinity which is high and stable varied from 33.1 to 35.2. The pH varied from 7.94 to 9.46, and it decreased at first and then stabilized. The range of dissolved oxygen varied from 7.46 mg/L to 10.43 mg/L and the dissolved oxygen was sufficient. The range of chemical oxygen demand varied from 0.57 mg/L to 4.57 mg/L, showing an increasing pollution trend. The range of inorganic nitrogen varied from 0.03 mg/L to 0.18 mg/L, which was low comparatively. The active phosphate ranged from 0.009 mg/L to 0.208 mg/L and it increased remarkably in the later stage of aquaculture. The range of N/P ratio varied from 0.68 to 17.22 and it increased first and then decreased sharply. It shows that the nutritional status of pond water evolved from oligotrophic in the first stage, and then, to the potential eutrophication status with nitrogen limitation in the later stage.