Abstract: A one-month laboratory experiment was conducted to study the effects of Bellamya aeruginosa bioturbation on the sediment oxygen consumption rate and overlying water nutrient fluxes in a simulated algal bloom water body. Three treatment groups and one control group were set up in the experiment, according to the stocking density of B. aeruginosa. Throughout the trial period, the sediment oxygen consumption (SOC) rate in treatment and control groups declined significantly. The SOC rate in treatment groups was higher than that in control group at the initial stage of the experiment, but lower than that in the control group at the late stage of the experiment. The treatment groups with high density B. aeruginosa showed a higher SOC rate than the treatment groups with low-density B. aeruginosa. In control group, ammonium always released from the sediment to the overlying water, and the release rate decreased gradually; while in treatment groups, ammonium was released to the overlying water at initial stage but absorbed by the sediment at middle and late stages of the experiment. Except at the initial stage of the experiment, the fluxes of nitrite and nitrate in all treatment groups and control group were mainly released to overlying water, and there was a significant difference between treatment group 1 and control group. Phosphate was released from the sediment at early stage, and was absorbed into sediment by the end of the experiment. This study revealed that the bioturbation of B. aeruginosa increased the SOC rate at the beginning but decreased the SOC rate by the end of the experiment, and the existence of B. aeruginosa enhanced the overall sediment nitrification rate, consequently speeded the sediment-water N cycling.

Key words: Tropical rain forest, Endangered species, Photoinhibition, Photosynthetic acclimation, Antioxygenic enzymes, Flexibility