The number of metagenomic sequences of aquatic biota in China's water bodies

Harmful Microcystis proliferation severely threatens aquatic ecosystems globally, but their impacts on food-web stability remain poorly understood. Here, we analyzed 1,309 metagenomic samples from freshwater ecosystems across China to investigate how Microcystis abundance affects synchrony among taxa in multi-trophic food-webs (from bacteriophages to piscivorous fish). We found that Microcystis abundance significantly positively correlated with anthropogenic factors (e.g. GDP, population density, nitrogen and phosphorus emissions), and their proliferation strongly enhanced synchrony between aquatic taxa (enhanced synchrony normally correlate low stability), whereas other aquatic taxa (e.g., fish, zooplankton and bacteria) showed no clear enhancing effects on the synchrony. The enhanced synchrony caused by Microcystis proliferation occurred more frequently between the consumers and their foods than between the aquatic taxa without consumer-food relationship. Moreover, trophic cascades more strongly drove these synchrony dynamics in middle and high trophic-levels, while synchrony in low trophic-levels was mainly affected directly by Microcystis. Overall, our results reveal ecosystem stability relies strongly on trophic linkages and provide a pioneering framework for integrating extensive metagenomic datasets to enhance our understanding of ecosystem stability across broad taxa spectrum.