Impact of Litopenaeus vannamei bioturbation on nitrogen dynamics and benthic fluxes at the sediment-water interface in pond aquaculture

We investigated the effects of the bioturbation of Litopenaeus vannamei at the sediment-water interface through field experiments and ex situ incubation. Sediment oxygen consumption (SOC), benthic nitrogen dynamics (nitrification, denitrification, and nitrate ammonification), and the benthic fluxes of NH4 (+)-N, NO3 (-)-N, NO2 (-)-N, and soluble reactive phosphorus were measured monthly from April to September. The results showed that L. vannamei promoted SOC and decreased the concentration of dissolved oxygen in the bottom water. Enhanced nutrient release from the sediments to the overlying water due to L. vannamei was observed, which consequently enriched the bottom water. The presence of L. vannamei inhibited nitrification later in the cultivation period and hardly had any significant effects on denitrification and nitrate ammonification throughout the study. The results suggest that farmers should more thoroughly consider changes in the benthic fluxes of oxygen and nutrients, as these aspects could be influenced by shrimp bioturbation, whereas benthic nitrogen dynamics in aquaculture ponds were comparatively less influenced.