Substituting photoautotrophic with heterotrophic Chlorella species for water quality regulation and microbial community modification in Litopenaeus vannamei pond culture

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The study aimed to assess the replacement of photoautotrophic cultivated Chlorella vulgaris with heterotrophic cultivated C. pyrenoidosa as the inoculated algal fluid for analyzing effluent nutrient removal and regulating bacterial community dynamics in Litopenaeus vannamei outdoor pond culture system. Two separate treatment outdoor earthen ponds were utilized; one supplemented with C. vulgaris (CV pond) while the other supplemented with C. pyrenoidosa (CP pond), each stocked at a density of 80 animals m −3 in the two ponds for a period of 30 days. Regular sampling was performed on water and L. vannamei individuals from both sets of ponds to evaluate water nutrient parameters, bacterial community composition, and growth parameters correspondingly. The shrimp in the CP pond exhibited a weight gain rate and specific growth rate of approximately 157.32 ± 0.43 % and 3.11 ± 0.01 %, respectively, while those in the CV pond demonstrated rates around 159.53 ± 0.36 % and 3.15 ± 0.01 %, with no statistically significant differences observed between the two groups. Consequently, both ponds displayed similar patterns of microalgae proliferation after inoculation throughout the 30-day experiment, with no significant variation detected in algal cell density. The inoculation with C. pyrenoidosa demonstrated enhanced removal efficiency of PO 4 3- -P and NH 4 + -N, along with regulation of pH and BOD/COD levels in shrimp ponds. Inoculating with C. pyrenoidosa further enhances microbial diversity and richness within aquaculture ponds by promoting an abundance of beneficial bacterial taxa such as Proteobacteria, Actinobacteria, Alphaproteobacteria, Gracilibacteria, Luteolibacter, and Exiguobacterium. Redundancy analysis reveals that microalgae species primarily regulate bacterial communities by exerting influence on water quality factors. These findings offer crucial insights into the utilization of heterotrophic cultivation microalgae for shrimp aquaculture by examining their impact on water quality factors and microbial community structures within shrimp cultural ecosystems.