Distribution of nutrients in the pore water and overlying water in Grass carp Ctenopharyngodon idellus polyculture system

Abstract:

Spatial distribution of NH⁴-N, NO³-N, NO²-N and PO⁴-P in overlying water and pore water, and the change of TN, TP and TC concentrations in sediments in Grass carp Ctenopharyngodon idellus polyculture ponds were studied by means of land-based enclosure during June~October, 2009. The results showed that: (1) the concentrations of NH⁴-N, NO³-N, NO²-N, and PO⁴-P were 0.056~1.499, 0.022~0.228, 0.049~3.903, and 0.003~1.882 mg/L, respectively. The proportion of NH⁴-N in the DIN increased over time in the horizontal pore water. Different systems showed different vertical distribution of nutrients. (2) During the experiments, the concentrations of TN and TP didn't change significantly. However, the concentration of TC decreased significantly, especially in GSC. It is suggested that the accumulation of organic matter and potential release of NH⁴-N in the underlying water can be reduced effectively in Grass carp polyculture system. Therefore, this system might be applied in aquaculture.