Effects of Different Submerged Macrophytes on the Water and Sediment in Aquaculture Ponds with Enrofloxacin Residues

Abstract

Submerged macrophyes have been widely used to restore aquaculture ponds in recent years. Yet, whether the residual antibiotics in ponds will affect the remediation effect of submerged macrophyes, and the effect of different submerged macrophyes on the water and sediment in aquaculture ponds with antibiotic residues, is unclear. A microcosm experiment was carried out to study the interaction between three kinds of submerged macrophytes and their growing environment with antibiotic residues. Ceratophyllum demersum L. with no roots, Vallisneria spiralis L. with flourish roots, and Hydrilla verticillata L with little roots were chosen to be planted in the sediment added with enrofloxacin (ENR). The growth of submerged macrophytes, the changes of the overlying water and sediment characteristics, and the microbial community in the sediment were analyzed. The results showed that according to the growth rate and nutrients accumulation ability, V. spiralis with flourish roots performed best among the three submerged macrophytes. The concentrations of TOC, TP, NH4+-N, and TN in the overlying water were 25.0%, 71.7%, 38.1%, and 24.8% lower in the V. spiralis treatment comparing with the control, respectively. The richness and diversity of the microorganisms in the sediment of V. spiralis treatment were significantly higher than those in the control, but this advantage was not obvious in the H. verticillata treatment. V. spiralis promoted the growth of Proteobacteria (22.8%) and inhibited the growth of Acidobacteria (32.1%) and Chloflexi (31.7%) in the rhizosphere sediment with ENR residue. The effects of the three submerged macrophytes on the removal of ENR from sediment were not reflected due to the limitation of water depth. Compared with C. demersum and H. verticillata, V. spiralis was more suitable for the remediation of the aquaculture ponds with ENR residue.