PHYTOPLANKTON COMMUNITY STRUCTURE IN AN INTEGRATED MULTI-TROPHIC AQUACULTURE SYSTEM REVEALED BY MORPHOLOGICAL ANALYSIS AND HIGH-THROUGHPUT SEQUENCING

With increasing concern over the negative environmental impact of mariculture, integrated multi-trophic aquaculture (IMTA) has received extensive attention in recent years. To comprehensively assess the phytoplankton community structure in the late culture stage of a typical pond IMTA system, both morphological analysis and high-throughput sequencing method were used in the present study. 9 phyla of phytoplankton were identified by using the two methods, and the Bacillariophyta, Cyanophyta and Euglenophyta were the most dominant. The dominant phytoplankton of the IMTA pond system in which clams were reared in a separate pond has changed from cyanophytes to diatoms from September to October, and it has changed from diatoms and cyanophytes to euglenophytes, haptophytes and green algae in the IMTA pond with shrimp, crab and clam together. Results of direct gradient analysis revealed that the phytoplankton community structure seemed to be linked with the variables of temperature, salinity, pH, dissolved inorganic nitrogen (DIN) and dissolved silica (DSi) concentrations, DIN/dissolved inorganic phosphorus (DIP), DSi/DIN and DSi/DIP. The relationship between phytoplankton community and Vibrio abundance indicated that diatoms and chlorophytes might inhibit the proliferation of Vibrio , while cyanophytes bloom might be beneficial to the Vibrio growth.