Characteristics of planktonic microalgae community changes in integrated multi-trophic ponds of shrimp, fish and shellfish

【Objective】 To study the community change characteristics of planktonic microalgae in integrated multitrophic ponds of shrimp, fish and shellfish, which could provide theoretical basis for the healthy breeding of Litopenaeus vannamei and the water quality regulation of the aquaculture ponds. 【Method】 Multi-trophic ponds farming Litopenaeus vannamei, Ctenopharyngodon idella, Ictalurus punctatus and Sinonovacula constricta were selected from Maoming, Guangdong. Water samples and planktonic microalgae samples were collected respectively in the pre-stage, mid-stage and late stage of aquaculture. The changes of water quality indicators and planktonic microalgae communities during the aquaculture process were analyzed, and redundancy analysis（RDA） was conducted on them. 【Result】 As the aquaculture stage progressed, the contents of nitrogen nutrients such as ammonia nitrogen, nitrate nitrogen and nitrite nitrogen in the pond water showed an increasing trend. During the entire aquaculture process, the density of planktonic microalgae in the pond was 1.65×10⁶-9.34×10⁶ cell/L. The total biomass of planktonic microalgae showed an increasing trend with the progress of the aquaculture stage. At different aquaculture stages, a total of 53 genera and 8 phyla of plankstatic microalgae were identified, among which there were 28 genera in the Chlorophyta, 10 genera in the Cyanophyta, and 6 genera in the Bacillariophyta. The genera Merismopedia and Oscillatoria of the Cyanophyta were the dominant quantitative genera, while the genera Cyclotella of Bacillariophyta, Scenedesmus of Chlorophyta, and Anabaena of Cyanophyta were the dominant genera in terms of biomass. During the entire aquaculture process, the quantitative diversity index of the plankton microalgae community in the pond was 1.32-2.83, and the biomass diversity index was 2.85-3.89. The RDA results showed that the environmental factors affecting the planktonic microalgae community in multi-trophic ponds of shrimp, fish and shellfish were mainly nitrogen and phosphorus nutrients. 【Conclusion】 Multi-trophic aquaculture mode of Litopenaeus vannamei, Ctenopharyngodon idella, Ictalurus punctatus and Sinonovacula constricta can effectively control the proliferation of planktonic microalgae in ponds during the aquaculture process, and maintain the planktonic microalgae community diversity, which is conducive to the aquaculture water environment.