Antarctica: Researchers have discovered that zooplankton, minute marine animals like copepods, krill and salps undertake a remarkable seasonal migration in Antarctic waters, during which they lock away millions of tonnes of carbon deep in the ocean.
A tiny, often-overlooked ocean creature commonly sold as fish food has been found to play a vital role in protecting the Earth from climate change, according to new research.
Dr. Guang Yang from the Chinese Academy of Sciences stated that, “These animals are unsung heroes. This forces a rethink about how much carbon the Southern Ocean can store.”
Each year in spring, zooplankton gorge on phytoplankton at the ocean surface, storing carbon as fat. Then, as winter approaches, they sink hundreds of metres to depths between 500m and 2km, where they go dormant and slowly burn this fat. This deep-sea fat metabolism traps the carbon for decades or even centuries, preventing it from warming the atmosphere.
This seasonal vertical migration pump sequesters around 65 million tonnes of carbon annually roughly the same as the yearly emissions of 55 million diesel cars, according to the US Environmental Protection Agency’s carbon calculator.
Prof. Daniel Mayor from the University of Exeter explained that, “Without this natural process, our planet’s atmosphere would be significantly warmer. The fat inside their bodies acts like a carbon battery pack that slowly releases CO₂ deep down, where it’s kept out of the atmosphere for a very long time.”
Scientists had previously known that zooplankton played a role in carbon storage through their sinking waste, but this new research quantifies the much larger contribution made during their epic vertical migrations.
Data from nearly a century of observations was analysed by the international research team, including scientists from the British Antarctic Survey. They also carried out new fieldwork onboard the polar research vessel Sir David Attenborough, using red light to study the animals in near-total darkness and freezing conditions to avoid disturbing their behaviour.
However, researchers warn that this critical natural process is under threat. Climate change, warming seas, and increasing krill harvesting, nearly half a million tonnes were caught in 2020 alone could reduce zooplankton populations and undermine their carbon sequestration ability.
Prof. Daniel Mayor from the University of Exeter remarked that, “If this biological pump didn’t exist, atmospheric CO₂ levels would be roughly twice what they are now. The oceans are doing a pretty good job of mopping up CO₂, but we risk damaging that system.”
Environmentalists have called for more regulation of krill fishing, particularly in sensitive Antarctic waters. The study’s authors also urge that their findings be integrated into global climate models to ensure accurate forecasts of future warming.
Co-author Dr. Jennifer Freer noted that, “Compared to whales and penguins, these creatures might not be glamorous. But they’re essential. Without them, we’d be in much deeper trouble.”
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