Bacterioplankton community composition in alpine lakes

The light-to-nutrient hypothesis proposes that under high light-to-nutrient conditions, bacteria tend to be limited by phosphorus (P) because high light energy and low nutrient availability would decrease phytoplankton biomass production. In contrast, under relatively low light-to-nutrient conditions, bacteria would likely be driven towards carbon (C) limitation. However, little information on whether high-altitude lakes with abundant allochthonous C fit the above hypothesis is available. We investigated bacterioplankton community composition fora few high-altitude lakes. The findings clearly showed that bacteria in above-tree-line lakes were limited by P, in contrast, bacteria in below-tree-line lakes are not limited by carbon, where phytoplankton was limited by light due to fast light attenuation by humic substances.