The Antarctic Ocean and the importance of krill

Where Tiny Crustaceans Are Saving Our Climate

Antarctica is far more than just an icy wilderness at the end of the world. Surrounded by the mighty Circumpolar Current, which flows around the continent like a massive ring, it forms a unique, self-contained ecosystem. In this extreme habitat, an unassuming hero plays a central role: krill.

The Southern Ocean is an ocean of extremes and is home to a good 90 percent of the world’s ice. The area covers ten percent of our planet’s total ocean surface. Every year, new sea ice the size of Europe, one and a half meters thick, forms here. Freezing downdrafts, known as katabatic winds, with speeds of up to 300 kilometers per hour, whip from the glaciers toward the sea, creating unique conditions: When these winds drive cold, dry air masses from the ice plateaus out over the sea, their force tears the sea ice apart. Due to the extreme cold, new ice quickly forms in the resulting open water areas. During this freezing process, salt is expelled from the ice and dissolves in the seawater. The salt-rich and thus heavy water sinks.

This process plays a key role in the formation of Antarctic bottom water, a dense water mass that plays a key role in global ocean circulation. The increased salt concentration creates Antarctic deep water, which flows northward like a sluggish current over the seafloor at depths of 4,000 to 5,000 meters.

Krill: Small Crustacean, Big Impact

In this extreme environment, shrimp-like crustaceans known as krill thrive. Krill is a collective term for nearly 90 species of crustaceans. The order Euphausiacea encompasses various families, genera, and ultimately the individual species classified as krill.

Antarctic krill is a species of crustacean from the family Euphausiidae that lives in the Southern Ocean in the waters around Antarctica. Like other species classified as krill, Euphausia superba belongs to the shrimp-like invertebrates that live in large swarms.

The order Euphausiacea: With a total biomass of around 450 million tons, their mass is roughly equivalent to that of the entire human population. This sheer quantity makes them the foundation of the Antarctic food web: Whales migrate thousands of kilometers to feed on them, and penguins, seals, seabirds, and fish depend on them. Together, these marine creatures consume about 250 million tons of krill annually, the majority of which is Euphausia superba.

Natural CO₂ reservoirs in action

But krill is far more than just food. These tiny crustaceans act as natural climate protectors through a fascinating mechanism: their fecal pellets and shed exoskeletons sink into the depths of the ocean, carrying bound carbon with them. In just a small area near the Antarctic Peninsula and in the Scotia Sea alone, 23 million tons of carbon can be permanently stored each year.

The cold Antarctic water further enhances this effect, as CO₂ dissolves much more readily at low temperatures. Combined with the slow deep-water circulation, the carbon is stored harmlessly in the ocean depths for millennia. The Southern Ocean accounts for up to 40 percent of total oceanic CO₂ uptake—one of the largest carbon sinks on Earth.

Threat from Human Appetite

Yet this finely balanced system is coming under increasing pressure. Humans have discovered krill as a new resource—for food, dietary supplements, and cosmetics. Industrial krill fishing threatens not only individual species but the entire Antarctic food web.

At the same time, climate change is exacerbating the problem: Since 1880, the global average temperature has risen by 0.8 degrees, with three-quarters of that increase occurring since 1970. The CO₂ concentration in the atmosphere climbed from 300 ppm in the 1950s to over 400 ppm in 2013. Forecasts predict levels between 800 and 1,000 ppm by 2100—with dramatic consequences.

Sea levels have already risen by 20 centimeters, and further rises of over a meter are likely. But the threat goes far beyond that: Ocean acidification caused by dissolved CO₂ is fundamentally altering marine ecosystems. If krill populations collapse, we will lose not only a central food source for countless marine animals, but also a very important natural CO₂ sink on our planet. The released carbon dioxide would further accelerate the climate crisis—a vicious cycle that will already affect our grandchildren’s generation.

Protecting krill is therefore far more than just species conservation: it is active climate protection for future generations.

More information about krill on Taucher.Net
2026: The battle for krill in Antarctica
2018: License to Krill
2017: Why do krill stocks in Antarctica fluctuate?