Regulatory roles of core microorganisms on nutrients in aquaculture pond sediments: Implications for sustainable aquaculture management in China

Core species-driven microbial communities in sediments are crucial for regulating nutrient transformation and maintaining the health of freshwater aquaculture ponds, yet studies at large spatial scales remain limited. In this study, 16S rRNA gene Illumina sequencing was employed, and 130 aquaculture ponds across a range of 2,393 km from the south to the north of China were analyzed to identify core species. The results showed that the average contents of total nitrogen (TN), total phosphorus (TP) and organic matter (OM) in the surveyed fishpond sediments were 2,087 mg/kg, 1,775 mg/kg and 5.87%, respectively. Notably, the northern and southern areas of China exhibited higher loads of OM, total carbon (TC), total organic carbon (TOC) and TN in the sediments. The nutrient loads had a latitudinal gradient pattern that was influenced by fishpond environmental conditions and core microorganisms, with reduced core species diversity at higher latitudes and higher microbial diversity but with weaker microbial interactions. Fish farming activities such as dietary protein, stocking amount, sediment quality improver, feeding quantity and water depth played more significant roles in shaping the latitudinal gradient pattern of sediment nutrients regulated by core microorganisms than natural environmental conditions did. Core microorganisms such as Lentimicrobium sp. and Gp6 sp. in the southern area, Gp7 sp. in the central area, Klenkia sp. and Gemmobacter sp. in the northern area could respond to changes in environmental changes, and regulated sediment nutrient migration and transformation through their metabolic activities. This study provides a scientific basis for the optimizing management of in freshwater fishpond aquaculture. • Sediment nutrient loads of aquaculture fishponds across China were investigated. • Sediment nutrients exhibited higher loads in southern and northern areas of China. • Latitudinal gradient pattern of nutrients mainly affected by culturing activities. • Fishpond sediments at higher latitude harbor more diverse array of microorganisms. • Core species played key roles in regulating fishpond sediment nutrient loads.