Why scientists are counting tiny marine creatures from Space

Scientists say that by detecting subtle color differences in seawater, they are able to monitor from space the tiny but crucial marine organisms in Antarctic waters – Antarctic krill.

This new research targets Antarctic krill, which are only a few inches long, but are among the most abundant and important animals on Earth. Marine life, including whales, penguins, seals, and seabirds, all feed on these tiny creatures.

However, conservation scientists are concerned that fishing activities and climate change may negatively impact krill, so they believe we need new methods to monitor these organisms. "Antarctic krill are the superheroes of the Southern Ocean," said Rod Downie, chief polar advisor at the wildlife charity WWF-UK. "They are the tiny, unsung heroes that sustain an incredible array of marine life, but climate change and unsustainable fishing are putting them at risk."

Researchers at the University of Strathclyde, the World Wildlife Fund, and the British Antarctic Survey (BAS) are developing a new method using satellites to determine the number of krill in the ocean around Antarctica. The key lies in the differences in light absorption of seawater, which depends on the number of krill swimming in the water. Dr. Cait McCarry of the University of Strathclyde has just returned from an expedition to Antarctica, where she captured krill in order to measure this effect. "We start with seawater, then add one krill and measure the light absorption of the water," she explained. "Then we add another krill and measure again."

Researchers say that by analyzing how krill density changes the color of the ocean, they can use satellites to take snapshots of krill populations, thereby monitoring krill populations from space. Krill are food for some of the largest animals on Earth, including baleen whales that migrate thousands of kilometers to Antarctica to feed on krill. They are also the foundation of a healthy ocean and part of a virtuous cycle: whales eat krill, and krill eat tiny plants that live in sea ice, which absorb carbon that causes global warming as they grow. When whales defecate in large quantities, they fertilize these ocean plants that have a cooling effect.

However, as global warming causes ocean temperatures to rise, conservation scientists worry that this cycle could be disrupted and krill could become vulnerable. Mr. Downie said: "We urgently need to better manage fisheries and protect krill habitats in a network of marine protected areas. This project can provide us with a new tool to help monitor and protect this vital species."