Melting Glaciers Feed Antarctic Food Chain

Nutrient-rich water from melting Antarctic glaciers nourishes the ocean food chain, creating feeding “hot spots” in large gaps in the sea ice, according to a new study.

New research finds that iron stored in the region’s glaciers is being shuttled by melting water to open areas of the ocean, called polynyas, where it stimulates growth of phytoplankton, ocean algae that form the base of the marine food chain. Krill and fish thrive on phytoplankton, and these smaller animals support penguins, seals and whales that feed and breed in the polynyas that ring the Antarctic coast, according to new research.

Increased melting of Antarctic glaciers in the coming decades, which scientists say could occur as a result of climate change, could cause a spike in the amount of iron in the polynyas, according to the new study. The increased iron could boost phytoplankton in these open areas, potentially providing more food for the entire food chain, suggests the new study accepted for publication inJournal of Geophysical Research: Oceans, an American Geophysical Union journal.

“These coastal polynyas are sensitive to inputs from adjacent glaciers, and these glaciers are probably going to accelerate their melting in the future, which is certainly going to have implications for these polynyas,” said Kevin Arrigo, a biological oceanographer with the Department of Earth System Science at Stanford University in  California, and lead author of the new study.

“Coastal Antarctica is likely to become a more productive place in the future,” Arrigo said.

Polynyas are created during the summer when winds whip off the Antarctic Ice Sheet, pushing floating sea ice away from the shore. These open areas of water, which range from the size of San Diego to an area equal to the Great Lakes, are hot spots for phytoplankton and, in turn, the entire ocean food chain, according to Arrigo.

“When you look at satellite images of ocean color, these areas just light up [green] compared to the [blue] waters around them,” he said.

The new research by Arrigo and his team suggests that the amount of water leaving melting Antarctic glaciers is the largest driver behind the abundance of phytoplankton in the polynyas, not sunlight or temperature as scientists had previously thought. Larger amounts of water coming off the glaciers carry more iron into the polynyas, which should simulate more phytoplankton growth, according to the new study.

Source: en.tempo.co