State of the Planet

News from the Columbia Climate School

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The Arctic’s Secret Garden

The small town of Barrow, Alaska, is perched on a point of land 320 miles above the Arctic Circle, where stark, flat tundra stretches in one direction and a vast expanse of Arctic Ocean extends to the horizon in the other. For most of the year a thick layer of sea ice covers this entire ocean. Even during the height of summer, a partial covering of ice remains, and the ocean temperature doesn’t rise above 35 degrees Fahrenheit. Despite these seemingly inhospitable conditions, tiny marine organisms thrive in this frigid environment.

In early May, when daylight lasts nearly 24 hours, large populations of algae grow in and just beneath Arctic sea ice. With the availability of ample sunlight and nutrients, billions of these tiny photosynthesizing plants quickly reproduce, or bloom, giving the bottom layer of the ice a distinctive golden-brown hue. After several weeks, the algae are released into the sea, where they become a source of food for larger organisms, including zooplankton, fish and whales.

Lamont-Doherty Earth Observatory marine biologists Craig Aumack and Andy Juhl spend a month each spring in Barrow studying the algae dwelling in and under the sea ice. Their goal is to learn more about the different species of algae that compose these communities and their role in the Arctic marine food web.

Aumack and Juhl are finding that the thickness of sea ice and the associated snow cover, as well as the timing of sea ice melt in spring and freeze in autumn, may all affect the productivity of the ice algae community, which in turn, affects the larger marine organisms that feed on the algae.

Their research provides valuable baseline information on the relationship between sea ice and algae in the Arctic ecosystem and sheds new light on the Arctic’s basic biological processes—vital data that increases understanding of this important ecosystem and how it may be affected by climate-driven changes.

“If we want to be able to predict what the future may look like, we need to understand the various factors that control the dynamics of this algae as the Arctic climate changes,” said Juhl.

“Investigating Life in Arctic Sea Ice,” filmed in May 2013, shows Aumack and Juhl conducting fieldwork on the massive ice sheets covering the Arctic Ocean. The scientists set up three different sampling sites on the ice, where several times a week they spend up to 12 hours collecting ice cores, taking measurements and deploying a small remotely operated vehicle (ROV) to capture images and video under the ice. In the film, views of a large algae community are seen, as are organisms on the seafloor, such as jelly fish and small crustaceans called isopods, both of which may feed on the algae once it’s released into the ocean.
“The Arctic’s Secret Garden,” was filmed during the same field season by a camera attached to the ROV; it shows two different algal communities growing at the bottom of the sea ice. This footage, recorded over the course of three weeks, shows an algal bloom at its peak and how that community is released into the sea, enabling another type of algae to bloom in its place.

For more information on Aumack and Juhl’s Arctic research, visit the project website or follow Lamont-Doherty Earth Observatory and the hashtag #LDEOarctic on Twitter. You can also read the expedition blog posts on State of the Planet.

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