Efficacy of the ‘three ponds and two dams’ ecological treatment system in purifying shrimp pond wastewater and mitigating antibiotic resistance

Shrimp pond aquaculture, like fish pond culture, faces significant challenges such as water pollution and antibiotic resistance, driven by chemical overuse and untreated effluent discharge. This study evaluates the efficacy of an ecological treatment system in treating shrimp pond wastewater, focusing on water quality improvement, microbial community dynamics, phytoplankton composition, and antibiotic resistance gene (ARG) mitigation. Using adjacent river indicators as a reference, comparative analyses were conducted on phytoplankton density and biomass, key water quality parameters, and microbial parameters in shrimp culture and ecological ponds across key growth stages and the pond cleaning period. Bacterial 16S rRNA gene sequencing was employed to assess bacterial community diversity and composition in water and sediment. Additionally, the abundance of 12 ARGs was quantified, and their correlations with bacterial communities were analyzed. Results demonstrated that the ecological treatment system significantly improved water quality, with the ecological pond consistently exhibiting lower levels of key water quality parameters compared to the culture pond. Phytoplankton density and biomass were highest in the culture pond, while the ecological pond maintained intermediate levels, acting as an effective buffer. Microbial analysis revealed reduced bacterial and coliform counts in the ecological pond. ARG abundances were highest in the culture pond, whereas the ecological pond showed marked reductions. Dynamic correlations between ARGs and bacterial genera, such as Pseudomonas, were observed, highlighting the system's potential to mitigate antibiotic resistance. This study underscores the ecological treatment system's effectiveness in purifying shrimp pond wastewater, reducing microbial contamination, and providing critical insights for system optimization.