Blooming Amazing: Life Grows Under Arctic Sea Ice

Arctic melt ponds

This spring, scientists, crew, and guests—including an elementary school teacher from Palo Alto, CA—set sail from Dutch Harbor in the Aleutian Islands on the U.S. Coast Guard Cutter Healy bound for the Arctic. A voyage so early in the season is unusual, risky even, but could shed new light on a mystery dating back to 2011.

It was then, in the Chukchi Sea, north of Alaska, scientists aboard the Healy first made an unusual discovery – phytoplankton growing underneath the thick sea ice, acres of it, the largest bloom ever discovered in the Arctic.

Phytoplankton, like other plants, needs light to thrive, but the ice was, up until then, thought to be impenetrable by light. Scientists hypothesized that rapidly thinning sea ice and widespread melt ponds were allowing more sunlight to penetrate to the water underneath, likely simulating phytoplankton growth.

Arctic Spring 2014

So in May, three scientists from the 2011 expedition—Stanford’s Kevin Arrigo, Woods Hole senior scientist Bob Pickart, and Darmouth’s Don Perovich—regrouped and set out with a fresh crew of 150 to take a closer look at the ice and measure early plankton growth.

Kevin Arrigo

Stanford’s Kevin Arrigo with the Healy. Image: Gert van Dijken

The “Arctic Spring” mission, the first of its kind to be conducted so early in the thaw, supported not only civilian scientists, but also Coast Guard researchers testing out unmanned vehicles and new oil-spill monitoring technology operating in the far north.

There are around 15 government and university research teams attached the 420-feet long, 16,000-ton Healy throughout its yearly missions, with myriad scientists and technicians working out of its on-board laboratories that include a main general laboratory, a wet lab, bio-chem lab, electronics lab, and meteorological lab.

“Science operations occur around the clock on Healy during the summer months in the Arctic region,” says Ensign Carolyn Mahony, a spokesperson for the Healy. “Conductivity, temperature and depth (CTD) casts are measures used to gain an understanding of water column characteristics and movement in a given region. CTD deployments and a variety of other scientific casts are routine evolutions on Healy, along with data collection on the ice.”

The Healy is built to withstand the harshest weather conditions. Her hull—1.5 inches thick and three to five times the thickness of most icebreakers—is reinforced with 2-inch thick steel plates. Her propellers and hull can handle ice chunks the size of a Volkswagen, and can power through almost 4.5 feet of sea ice at a steady 3 knots and 8 feet of ice by backing down and ramming.

The decline of sea ice

Sea ice covers about 25 million square kilometers (9,652,553 square miles) of Earth, and is an integral part of the climate and wildlife of the Arctic. The vast expanse of sea ice reflects the sun and keeps the region cooler, but warming temperatures are melting the ice over time, and then surface begins to absorb energy rather than reflect it, causing, in turn, more warming. Changes in the amount of sea ice can also disrupt normal ocean circulation.

According to the EPA, September 2012 had the lowest sea ice extent on record, 49 percent below the 1979–2000 average for that month. Over the last 30 years sea ice has declined by nearly 700,000 square miles, and multi-year ice has declined from more than 30 percent 1980s to seven percent in 2013.

Teaching kids about the environment

Educating youth about environmental changes is an important goal of the Healy mission. On board the ship, elementary school teacher Jan Arrigo profiled the research team and answered question from school children following Healy’s journey online. How fast does the Healy move? How big are walrus tusks? And does the sun ever set in the Arctic? All great questions posed by curious minds.

On its way back to port in Seattle, the Healy also made a stop in Juneau, Alaska, where it opened its doors for public tours. Among others, 100 grade-school children from Juneau-Douglas High School piled onto the ship to learn more about ice breaking and Healy’s scientific mission.

The evidence mounts

In all, Healy scientists spent four months in the Arctic measuring water and ice for nutrients, salinity, density, temperature and light penetration. From their data they hope to get a clearer understanding of sea ice, melt ponds, and blooms, as well as oceanographic pathways by which nutrient-rich winter water from the Bering Strait spreads across the Chukchi shelf.

Meanwhile, a newly published study from Canada’s Laval University shows that over the past 15 years once-unusual autumn blooms are also becoming more frequent in the Arctic, impacting fish and marine mammals at the top of the food chain as well as delicate ecosystems at the bottom of the sea. The conclusions are based on examination of satellite imagery and data collected by NASA.

“The occurrence of these fall blooms is possible due to both delayed sea-ice freeze-up and increased exposure of the sea surface to wind stress,” says Mathieu Ardyna, the study’s lead author.

Main image courtesy of NASA Goddard Space Flight Center on Flickr (CC BY 2.0)

Nancy Pardo contributed to this story.

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