Study shows how fish farming affects microbial communities, nitrate levels in pond ecosystems

Small-scale water bodies with areas less than 0.1 km², such as natural ponds, constitute the quantitative bulk of global inland water bodies, and are very susceptible to human disturbances and environmental change. In agricultural regions of China, water quality in ponds has deteriorated by high loads of nitrogen and phosphorous from agricultural sources.

Many natural water bodies and farmlands in rural China have recently been converted into fish farming ponds as part of an economic development strategy. Researchers today still have a limited understanding of how clusters of microorganism (or microbial communities), along with nitrogen and phosphorous fractions in the environment change when a natural pond is converted into a fish farming reserve.

A team of researchers from Huaiyin Normal University and the Institute of Agricultural Resources and Regional Planning in China has conducted a whole-ecology field experiment in a typically subtropical agricultural watershed in China to examine the microbial diversity of the surrounding area. The data from the study might give how fish farming affects microbial communities and nitrogen and phosphorous fractions in pond ecosystems. The team collected RNA samples from water samples in the pond ecosystem under study over a period of one year. Datasets of 16S rRNA amplicon sequencing experiments were collected and compared with the concentrations of nitrogen and phosphorous fractions from the corresponding water samples.

Bioinformatics analysis was used to analyze the diversity and structure of the microbial communities. The team's experimental results have indicated that the diversity and structure of the microbial communities has significantly changed after the conversion of a selected natural pond ecosystem into an aquacultural site. Dr. Jiangen Zhou, who led the study notes, "Fish farming also had a significant effect on nitrogen levels. Generally, when compared with nitrogen levels in the natural phase, the nitrate contents decreased substantially by 92.8% in the fish farming phase."

The findings have some implications for the environmental health as well as measures required to clean the water in such areas.

Our findings suggest that fish farming may be considered as an effective and ecological way to reduce nitrate pollution in ponds, especially with high nitrate levels. However, we should still be alert to the potential risk of environmental pollution of animal parasites or human pathogens caused by fish farming."

Dr. Jiangen Zhou, Huaiyin Normal University

Further research on how to cost-effectively and efficiently reduce nitrogen and phosphorous pollution through fish farming will be conducted in pond ecosystems in the future to improve existing knowledge on this area. The research has been published in Current Bioinformatics.