Synergistic Effect of Hard Clam Meretrix meretrix and Microalga on Elimination of Inorganic Nitrogen and Inorganic Phosphorus in Water
ZHANG Zhidong, CHEN Aihua, WU Yangping, ZHANG Yu, CAO Yi, CHEN Suhua, TIAN Zhen, LI Qiujie
Jiangsu Provincial Fine Breeds of Meretrix, Marine Economic Shellfish Research and Development Center of Jiangsu Province, Marine Fisheries Institute of Jiangsu Province, Nantong 226007, China
Abstract：Using the method of experimental ecology and response surface CCD model, four experimental groups were set up, namely, no clam without algae group (group O), clam without algae group (group A), algae without clam group (group B) and clam with algae group (group AB), with three replicates. According to the CCD model, 13 experimental groups were set up with the density of hard clam Meretrix meretrix (A) and the density of microalga Isochrysis galbana (B) as the influencing factors. The synergistic effect of clams and microalgae on the removal of inorganic nitrogen and inorganic phosphorus in water was investigated. The results showed that in clear water state (alga-free) environment, the elimination effect of the clam on inorganic nitrogen and inorganic phosphorus was not significant (P>0.05), it needed to cooperate with microalgae to significantly reduce the contents of inorganic nitrogen and inorganic phosphorus (P<0.05). The optimal proportion of clam and the microalga was 221 ind/m2 of clam and 1.92×106 cell/mL of microalga, and the maximal daily elimination rates in the water were 6.93% for inorganic nitrogen and 8.60% for inorganic phosphorus. The results of model prediction were accurate by verification of practical tests. Therefore, in the actual aquaculture process, the density of hard clam was about 225 ind/m2 (150 000 ind/667 m2) and the density of the microalgae was about 2.0×106 cell/mL, which achieved with the maximal daily elimination rates of (6.90±0.33)% for inorganic nitrogen and (8.57±0.29)% for inorganic phosphorus in the water.
2022, Vol. 41 
