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Melting Glaciers and Phytoplankton Health: Nutrient Run-Off Feeds Antarctic Marine Life

Aug 11, 2015 07:59 PM EDT
A phytoplankton bloom off the coast of Denmark in a gulf of the North Sea. Off Antarctica, phytoplankton similarly color the water with their numbers.
Iron-rich water melting off glaciers is causing phytoplankton to thrive, providing better nourishment for the rest of the marine chain.
(Photo : NASA Goddard Space Flight)

Melting glaciers: Not such a terrible story? Pretty hard to say that much for now. However, Kevin Arrigo with Stanford University and his research team recently found that melting Antarctic glaciers' nutrient-rich water is creating feeding "hot spots" in gaps in the sea ice, and their report on that was recently accepted for publication in the Journal of Geophysical Research: Oceans.

In the new research, iron stored in the glaciers melts into polynyas, which are open ocean areas. There, it increases the growth of phytoplankton, the ocean algae at the base of the marine food chain. Those are eaten by krill and fish, which are in turn consumed by penguins, seals and whales feeding and breeding in the polynyas of Antarctica, according to a release.

The theory is that increased melting could spike the iron that causes those phytoplankton to thrive and feed the rest of the chain. "Coastal Antarctica is likely to become a more productive place in the future," Arrigo said in the release.

Some polynyas are huge--they range from the size of San Diego to an area like that of the Great Lakes. They stir to existence in summer when winds push floating sea ice away from shore. In satellite images showing color, those areas light up green compared with the blue waters surrounding them, a release said.

This new research says that melting water drives the phytoplankton, not sunlight or temperature as scientists previously thought. The phytoplankton seem to be significant carbon sinks, as the release observed.

All that said, Arrigo maintains that in most cases, marine organisms will be negatively affected by warming water temperatures and acidification, according to the release.

In the study, researchers consulted 1997 to 2014 satellite images to learn how much phytoplankton grew in 46 polynyas around Antarctica's coast. Those numbers were compared with other data: the size of the polynyas, nearby glaciers' melt rate, and local seafloor width, noted the release.

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