SEASONAL PHYTOPLANKTON COMMUNITY PATTERNS AND INFLUENCING FACTORS IN FISH-MUSSEL SYSTEMS.

The rapid pearl farming industry causes environmental pollution to aquatic ecosystems. However, fish-mussel systems with highly productive, profitable and environment-friendly characteristics are appropriate aquaculture practices under the current polluted state of the environment in China. Phytoplankton are excellent indicators and play indispensable roles in maintaining the stability of a freshwater ecosystem. Therefore, samples were seasonally collected determine the seasonal phytoplankton community dynamics and potential driving factors in three subtropical reservoirs with integrated fish-mussel aquaculture. All water physicochemical parameters varied seasonally, and water quality had a trend of eutrophication. A total of 189 species were identified, among which Chlorophyta (83 species) dominated in species richness. Cyanophyta, in particular remained to be highly abundant (57.53% of the total seasonal biomass). The NMDS analysis indicated that summer was an independent branch. The CCA analysis and Spearman rank correlation analysis suggested that water temperature might be the main abiotic factor. Furthermore, pH, conductivity, DO, chlorophyll, TC and TN also significantly affected the community. The aquaculture enhanced the similarity in community structure which have happened due to predation pressure. The present study also identified the potential influences caused by the integrated fish-mussel aquaculture on phytoplankton seasonal succession, bringing some guidance to protect the reservoir ecosystem. [ABSTRACT FROM AUTHOR]