Mixotrophic microbes are single-celled organisms such as plankton and paramecium that are able to switch between photosynthesis and predation for survival. Plankton is the base food source for all marine trophic levels. Normally, these microbes employ photosynthesis, absorbing carbon and providing 70% of atmospheric oxygen. But their switch to eating other single-celled critters releases carbon.

The mechanism for the switch is not well understood, but appears to be triggered by a rise in the temperature of their environment. Their switching could indicate a tipping point for sustainable marine life and accelerate global temperature increase.