Effects of Jet Water Mixer on physicochemical parameters and bacterial abundance in Apostichopus japonicus pond

Jet Water Mixer (JWM) is a set of new water quality improvement equipment. To evaluate the effects of JWM on the pond water quality improvement, we monitored eight physicochemical parameters, including temperature, salinity, pH, dissolved oxygen (DO), total ammonia nitrogen (TAN), nitrous nitrogen (NO₂ ⁻-N), phosphate (PO₄ ³⁺-P), contents of sediment organic matter (TOM), abundance of living heterotrophic bacteria and culturable vibrio in the ponds of Dalian Zhuanghe Sea Cucumber Farm. The results show that compared with the control group, the contents of TAN and NO₂ ⁻-N were the lowest from March to November except for NO₂ ⁻-N in June; the PO₄ ³⁻-P content was the highest from March to August in JWM pond; the TOM content was the lowest in the sediment in each month (P<0.05). At thermocline and halocline stage, JWM increased the DO content significantly. JWM promoted the growth of living heterotrophic bacteria and restrained the growth of Vibrio as long as 8−9 months. It is concluded that JWM can improve water quality and reduce abundance of Vibrio in the water in spring, summer and autumn significantly, and reduce TOM content throughout the year, so it has a good application prospect in the cultivation of sea cucumbers.