Bioturbation of blood clam Tegillarca granosa on benthic nutrient fluxes and microbial community in an aquaculture wastewater treatment system

摘要

Using a mesocosm system, we investigated the influence of Tegillarca granosa on benthic-fluxes, sediment oxygen consumption (SOC), sediment properties, and vertical-dynamics of the microbial community in sediments of an aquaculture-wastewater treatment system. Incubation experiments for the nutrient fluxes and SOC were conducted, while 16S rRNA genes sequencing was performed to characterize changes in the microbial communities. The effluxes of ammonia-nitrogen, nitrate, nitrite, phosphate, SOC and sediment bacteria community in the treatments were significantly changed. Most benthic effluxes in the clam treatments were two-to five orders of magnitude higher than in the control. The total-nitrogen, total-carbon, and total-phosphorus contents in the treatments were 33%, 21%, and 46%, respectively, lower than in the control. Analysis of 16S rRNA genes revealed 71 major bacterial phyla with six phyla varying significantly among the treatments. The most predominant groups in the treatments included Proteobacteria, Bacteroidetes, Firmicutes, and Nitrobacter accounting for up to 62% of the total OTUs. These observations are considered to be caused by the T. granossa bioturbation which presumably promoted the mineralization process and created a conducive environment for the proliferation of microbial communities. The results suggest that T. granosa has the potential to promote benthic-fluxes, reduce organic wastes, modify bacterial community and remediate aquaculture effluents.