Impact of Effective Microorganisms and Chlorella vulgaris on Eriocheir sinensis and Water Microbiota in Ponds Experiencing Cyanobacterial Blooms

Cyanobacterial blooms threaten the quality and safety of the Chinese mitten crab Eriocheir sinensis . A combination of microalgae and probiotics seems a promising way to prevent and control cyanobacterial blooms in aquaculture ponds. In E. sinensis cultivation, however, a related strategy is still lacking. To assess the potential combined effects of effective microorganisms (EM) and Chlorella vulgaris on regulating cyanobacterial blooms, in this study, we detected the alterations in the physiology of E. sinensis , as well as water quality and microbial compositions of E. sinensis culture ponds with cyanobacterial blooms. As a result, supplementary EM and C. vulgaris had no adverse effects on the growth or digestive or antioxidant ability of E. sinensis but improved the water quality of the pond by reducing total ammonia nitrogen and total nitrogen levels. We found an increase in bacterial diversity and evenness, while a decrease in the diversity of fungal and phytoplankton communities was related to supplementary EM and C. vulgaris . Interestingly, EM coupling C. vulgaris promoted the restoration of the bacterial and fungal community composition in cyanobacterial blooms ponds, particularly the increase of Mychonastes abundance and the decrease of Cyclotella . This study laid the foundation for the prevention and control of potential risks in aquaculture.