Effects of Stocking Density of Filter-Feeding Fishes on Water Quality and Bacterial Community in Rice–Crayfish Polyculture System

Abstract

To evaluate the effects of filter-feeding fishes on water quality and bacterial community in the rice–crayfish coculture system, four different stocking densities of bighead carp (0, 500, 1000, 1500 ind./200 m2) were set up in rice–crayfish coculture systems. Water samples in the systems were collected biweekly to detect dissolved oxygen (DO), temperature (T), potential of Hydrogen (pH), ammonia nitrogen (NH4+-N), nitrite nitrogen (NO2−-N), nitrate nitrogen (NO3−-N), total nitrogen (TN), total phosphorus (TP), and Chlorophyll-a (Chl-a); the bacterial community in the water was analyzed simultaneously, then the correlation between water quality and microorganisms were studied. The results showed that concentrations of TN, TP, NO2−-N, and NH4+-N decreased while DO and NO3−-N increased along with the breeding process. NO2−-N, NO3−-N, TN, and NH4+-N were important environmental factors affecting the bacterial community structure in water (p 2 exhibited the best effect on the removal of nitrogen and phosphorus from the water body.

Keywords

• rice–crayfish
• coculture
• bighead carp
• water quality
• bacterial community