Bioremediation efficiency of Gracilaria verrucosa for an integrated multi-trophic aquaculture system with Pseudosciaena crocea in Xiangshan harbor, China.

摘要

The red algae, Gracilaria verrucosa, was co-cultivated with the fish Pseudosciaena crocea in an integrated multi-trophic aquaculture (IMTA) system for nearly two months in summer at coastal waters of Xiangshan harbor in the East China Sea. The nutrient reduction efficiency of ammonium and phosphorus was determined. Prior to the G. verrucosa co-cultured, the eutrophication index ( E) values of cage areas ranged from 4.2 to 32.0, indicating serious eutrophication conditions, and the high ratio of N/P and relative high P concentration indicated a nitrogen surplus. During the co-culture period, G. verrucosa showed efficiently at removing inorganic nitrogen (IN) and inorganic phosphate (IP), and maintained a more stable dissolved oxygen (DO) and chlorophyll a (Chl a) level in the IMTA system. The maximum reduction efficiency of PO 4-P, NO 2-N, NH 4-N and NO 3-N was 58%, 48%, 61% and 47%, respectively. Based on the DIN balance in the IMTA system, the optimal co-cultivation proportion of P. crocea to G. verrucosa in this area was 1 cage, 144.95 m 2 or 1 kg, 7.27 kg, respectively. Results of the present study indicated that environmental advantage could be achieved by integrating the red alga G. verrucosa co-cultured with fish at the open coastal waters in the East China Sea.