Bioturbation by the razor clam Sinonovacula constricta affects benthic nutrient fluxes in aquaculture wastewater treatment ecosystems

Abstract

The rapid development of the aquaculture industry has led to the growth of environmental problems. Bioremediation is an effective method for treating aquaculture effluents. A 30 d laboratory experiment was conducted to investigate the effects of Sinonovacula constricta bioturbation on sediment and nutrient fluxes across the sediment-water interface in aquaculture wastewater treatment ecosystems. The experiment was designed with 3 treatment groups and 1 control with 3 replicates each. The rates of sediment oxygen consumption (SOC) and the physical and chemical properties of the sediment and nutrient fluxes (NH 4 + , NO 3 -+ NO 2 -and PO 4 3-) were determined. After the experiment, the levels of total organic nitrogen, total organic carbon, and total phosphorus in the surficial sediment of the treatment groups had declined significantly, and the alkaline phosphatase content and microbial activity had increased significantly (p < 0.05). SOC rate in all treatment groups was significantly higher than that in the control group before Day 24 and increased with clam density (no. of clams per unit area) (p < 0.05); in most treatment groups, nutrients (NH 4 + , NO 3 -+ NO 2 -and PO 4 3-