Abstract:

To explore the phytoplankton community structure of the ponds after the standardization based on tertiary purification technology, from June 2022 to October 2022, the phytoplankton community in the water samples of each purification area of Eriocheir sinensis pond (T₁), Litopenaeus vannamei pond (T₂), largemouth bass pond (T₃) and grass and crucian carp (Ctenopharyngodon idella- Carassius auratus) polyculture pond (T₄) after the standardization in Suzhou City were tracked. Plankton community characteristics in different treatment areas were analyzed and studied, and the nutritional status of water was evaluated by phytoplankton dominant functional group. The results showed that the number of phytoplankton species in the T₁-T₄ experimental area was 85, 65, 59 and 66, respectively, and the number of phytoplankton functional groups was 20, 17, 17 and 18, respectively. The density and biomass size of phytoplankton functional groups were in the order of T₄>T₃>T₂>T₁, with the maximum value occurring from September to October. The Shannon Wiener diversity index was in the order of T₁>T₂>T₃>T₄, the richness index of Margalef was in the order of T₁>T₄>T₂>T₃, and the Pielou evenness index showed that the order of planktonic size was T₂>T₁>T₃>T₄. The dominant functional group of phytoplankton was mainly replaced by the M+MP functional group representing nutrient-entrophic/ultra-nutrient-rich water bodies, and the Lo-functional group with wide adaptability and the J-functional group of nutrient-rich water bodies. The environmental factors associated with phytoplankton dominant functional groups were TN and TP. Based on the dominant functional group of phytoplankton, the water environment status can be evaluated and the water quality changes can be analyzed in a timely and accurate manner.

Key words: pond aquaculture, standardized transformation, tail water treatment, functional group, environmental factors