Spatiotemporal variations and source tracking of antibiotics in an ecological aquaculture farm in Southern China.

ABSTRACT

Although the occurrence and distribution of antibiotics in aquatic environments and reared organisms have been widely reported, the spatiotemporal variations and sources of antibiotics throughout the rearing period of aquaculture remain unclear. In this study, the concentrations and spatiotemporal variations of antibiotics in water sources, pond water, sediment, feed, and reared shrimp samples during three rearing periods in an ecological shrimp farm in Southern China were investigated. The water, sediment, and feed samples were found to contain twelve, nine, and four types of antibiotics, respectively, and the concentration of erythromycin-H2O was the highest among these antibiotics. No target antibiotics were detected in the reared shrimp samples from this typical shrimp farm, which employed ecological rearing with no antibiotic use throughout the rearing processes. The total concentrations of antibiotics in water source were 1.96-40.58 times higher than those in pond water. A significant decrease in the total antibiotic concentrations of the pond water was observed, while a significant increase was observed in sediment during each rearing period (p < 0.05), suggesting that antibiotics transferred from the water phase to the sediment phase in the farm. Redundancy analysis demonstrated that the chemical oxygen demand was negatively correlated with the concentration of the target antibiotics in the water samples during three rearing periods (p < 0.05). The results of calculations conducted using the concentrations of antibiotics in the water source, pond water, sediment, and feed samples detected in this study indicated that the water source was likely to be the main source of antibiotics in the rearing ponds. This study can provide a better understanding of the spatiotemporal variations and sources of antibiotics in aquaculture.