Impacts of Corbicula fluminea on Oxygen Uptake and Nutrient Fluxes across the Sediment–Water Interface

Abstract

Corbicula fluminea (Asian clam) can assemble in high densities and dominate benthic communities. To evaluate the influence of this clam on sediment oxygen uptake and nutrient fluxes across the sediment–water interface, a microcosm study was conducted using a continuous-flow cultivation system with sediment, lake water, and C. fluminea specimens from Taihu Lake, China. C. fluminea destroyed the initial sediment surface, enhanced O2 penetration into the sediment partially, and increased the sediment water content, the volume of oxic sediment, and total microbial activity. Sediment O2 uptake was significantly stimulated by C. fluminea. Linear regression results for O2 uptake versus clam biomass ranged from 21.9 to 9.47 μmol h−1 g−1 DW (dry weight). The release of soluble reactive phosphorus, ammonium, and nitrate from the sediment was also increased by the clams. The increase in the amount of soluble reactive phosphorus and ammonium released into the overlying water was 0.042 ~ 0.091 and 2.77 ~ 3.03 μmol h−1 g−1 DW, respectively, and this increase was attributed to increased diffusion, enhanced advection between the pore water and the overlying water, and the excretions from C. fluminea. Enhanced nitrification was suggested as the reason for the increase in nitrate release (2.95 ~ 4.13 μmol h−1 g−1 DW) to the overlying water.