Original paper

The influence of different benthic fauna on inorganic nitrogen flux and denitrification in a large shallow hyper-eutrophic lake

Shang, Jingge; Liao, Qianjiahua; Zhang, Lu; Fan, Chengxin

Abstract

Different benthic species have different mechanical activities (sediment particle reworking, bioirrigation activities), thereby different species may have different bioturbation effects. To investigate the bioturbation effects produced by different functional groups of species (upward conveyors and biodiffuser groups) in a large shallow, hyper-eutropic lake, the Oligochaeta Limnodrilus hoffmeisteri and the clam Corbicula fluminea were selected as model organisms. Sediment samples with and without the model organisms were analyzed to determine the oxygen demand, nitrate, ammonium flux and denitrification rate. We found that both model species increased the sediment oxygen demand, nitrate, ammonium flux, and denitrification rates in the sediment. The results indicate that these two species exerted distinct impacts on the nitrogen turnover and denitrification. For example, Limnodrilus hoffmeisteri had greater bioturbation effects on solute exchange and denitrification across the sediment-water interface than Corbicula fluminea. Corbicula fluminea intensified the tendency of the bioturbated sediment to act as a source for inorganic nitrogen, whereas Limnodrilus hoffmeisteri caused the sediment to act as a sink for inorganic nitrogen. The results of our study confirm that the functional group approach is useful to study the bioturbation effects of benthic fauna on benthic fluxes and denitrification.

Keywords

bioturbationlake taihunitrogensinksource