Why zooplankton are the oceans carbon storage heroes

Zooplankton are one of the most diverse and abundant groups of organisms on Earth and they play an essential role in the marine food chain. Unable to photosynthesise, as phytoplankton do, zooplankton instead consume phytoplankton, forming a link in the food chain between primary producers and larger animals such as fish.

Zooplankton also store carbon from the atmosphere, which, when excreted by these organisms, for instance, can sink into the deep ocean, thus transporting carbon and locking it away. Without this biological carbon pump, atmospheric carbon dioxide levels would be around 50 per cent higher than they are today. But as our ocean warms, this zooplankton community is changing, becoming smaller and less nutritious. This trend poses a threat to global food security, with over a third of the world’s population relying on fish as a source of protein.

BIO-Carbon is a programme funded by the UK government’s UK Research and Innovation department that seeks to understand how much carbon zooplankton consume, where it goes and how the relationship between zooplankton and phytoplankton changes seasonally, thus influencing the flux of carbon in the deep ocean. A better understanding of this process and how it might evolve with our changing climate may inform climate models and help us take informed steps to mitigate the impacts of global warming on the marine carbon cycle and food webs.
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