EXPERIMENTAL-EVIDENCE FOR THE ROLE OF BIOTURBATION BY THE MARINE NEMATODE DIPLOLAIMELLA-DIEVENGATENSIS IN STIMULATING THE MINERALIZATION OF SPARTINA-ANGLICA DETRITUS

The effect of the bacterivorous nematode Diplolaimella dievengatensis on the diffusion of oxygen into sediment and the CO2 production of Spartina anglica detritus was examined in a laboratory experiment. Diffusion coefficients were calculated from measurements of both O2 consumption, using gas chromatography, and O2 micro-gradients, using micro-electrodes. After a transient state of about 10 d the diffusion and consumption of oxygen stabilized and approached steady state. In treatments with nematodes O2 consumption and CO2 production were 74 % higher than in controls. In treatments with nematodes the apparent diffusion coefficient of oxygen was 40 to 70 % higher than the molecular diffusion coefficient due to nematode activity. Since the increases of CO production and of the diffusion of oxygen in the presence of nematodes were of the same magnitude, we conclude that the enhanced turnover time of Spartina detritus was largely dependent on the bioturbation activity of the nematodes.