Abstract:With increasing concern over the negative environmental impact of mariculture, ecological aquaculture based on multi-trophic systems has received extensive attention in recent years. Phytoplankton are important components of aquaculture ecosystems. They are useful in maintaining water quality by uptake of nutrients during photosynthesis and serve as a direct or indirect food source for cultured organisms. Some phytoplankton, such as diatoms and green algae, are conducive to the growth of shrimp, crab, shellfish, and fish, whereas others (such as cyanophytes and dinoflagellates) may be toxic to aquatic organisms in aquaculture systems. In the present study, a combination of traditional morphological analysis and high-throughput sequencing was used to comprehensively assess phytoplankton community composition and diversity in the ecological aquaculture system of a marine pond in December 2018. Eight phyla were detected using two methods, Chlorophyta and Cryptophyta being the most frequently recorded. Notably, the phyla Haptophyta and Chrysophyta were only found via high-throughput sequencing. Additionally, a total of 39 genera were detected using two methods, but only five genera, Eutreptiella, Oscillatoria, Pseudonitzschia, Pyramimonas, and Teleaulax were shared in both methods. Some picophytoplankton (≤2 μm) and small nanophytoplankton (>2 μm and≤10 μm) were detected via high-throughput sequencing, but were not observed via morphological analysis. Picophytoplankton represented 25.24% of the total phytoplankton sequence abundance, and small nanophytoplankton accounted for 60.42%. Phytoplankton diversity revealed upon morphological analysis was lower than that revealed via high-throughput sequencing. Therefore, the combination of traditional morphological analysis and high-throughput sequencing will be useful for obtaining a comprehensive understanding of phytoplankton community composition and diversity in aquatic ecosystems. This study serves as a foundation for the characterization of phytoplankton community dynamics in the ecological aquaculture systems of marine ponds for future research.
