Study of Arctic algae ‘puts a microscope up to climate change’

As summer sea ice retreats and eventually disappears in the Arctic waters off Alaska, scientists studying phytoplankton predict changes in the species of algae present in the ocean water column, according to a paper featured as the cover article of Geophysical Research Letters in August.

“We’re putting a microscope up to climate change,” says Karen Frey, a co-author of the paper and an associate professor in Clark University’s Graduate School of Geography. “From a scientific perspective, any measurements we make are incredibly useful to get a sense of how not just the algae, but everything that relies on that algae in the food chain — all the way up to large mammals such as polar bears, whales, and walruses — may be impacted,” she says.

The researchers discovered that the warming climate and declining sea ice are contributing to changes in phytoplankton, or microscopic algae, favoring smaller species that offer less carbon and may be less nutritious for sea life. “It’s a cascading effect, a domino effect, in the food chain,” Frey says.

Half of all photosynthesis on the planet happens in the world’s oceans, she notes, and this includes the microscopic algae living in the Arctic Ocean. Marine plants thus play a significant role in the photosynthesis that generates oxygen and other byproducts for life on Earth. Phytoplankton and other marine plants utilize atmospheric carbon dioxide during photosynthesis; the byproducts of that process become nutrient-rich organic matter for animals farther up the food chain.

Frey and Aimee Neeley, a biological oceanographer at NASA’s Goddard Space Flight Center and now a doctoral candidate at the University of Maryland Center for Environmental Science, used data gathered in summer 2011 aboard the U.S. Coast Guard cutter Healy in the northern Chukchi and western Beaufort seas. The data were collected using a special microscope — called an imaging flowcytobot — and were subsequently used to model how different species of phytoplankton respond to sea ice, sea surface temperature, nutrients, salinity, and light.

Their research mission — and another in 2010 — was part of a multi-year, NASA-funded project called ICESCAPE (Impacts of Climate change on the Eco-Systems and Chemistry of the Arctic Pacific Environment).

Since then, Frey and Neeley have been assessing this enormous cache of data. Their paper, titled “Unraveling Phytoplankton Community Dynamics in the Northern Chukchi Sea under Sea‐Ice‐Covered and Sea‐Ice‐Free Conditions,” was published in August with Neeley’s dissertation adviser, Lora Harris, an associate professor in the University of Maryland Center for Environmental Science‘s Chesapeake Biological Laboratory.

“This study is novel in that it’s not just taking a broad-brush perspective, and saying that there’s going to be more phytoplankton or less phytoplankton with climate change,” Frey explains. “It’s drilling down and looking at the species of phytoplankton individually, and how those individual species may be impacted by environmental factors, and asking how might the presence of those species change with a warming climate and declining sea ice?”

Their research offers “one more piece in the puzzle” to help humans prepare for, and adapt to, significant changes on the Earth, brought on by climate change, she points out.

“There are predictions right now that perhaps by the year 2040, there will be no more perennial sea ice, there will be no ice at the North Pole in the summertime,” Frey says. Perennial ice is formed when summer (seasonal) ice doesn’t melt, and instead accumulates through a summer season, forming a thicker, more persistent sea ice pack.

“That’s not our kids or our grandkids, the way we used to talk about climate change; that’s us,” she adds.

Over the past eight years, Frey has made several research trips to the Arctic, most recently this past summer conducting research aboard a Canadian Coast Guard icebreaker, the Sir Wilfrid Laurier. In recognition of her expertise, the National Academy of Sciences appointed her to serve on the Marine Working Group of the International Arctic Science Committee (IASC), beginning in 2017. The IASC is a non-governmental, international scientific organization that encourages and facilitates collaboration on Arctic research.

In a 2012 Science article, Frey and her colleagues reported that climate change had led to an increase in the number of “melt ponds,” where sea ice has melted, in the Chukchi Sea. The melt ponds act as “sky lights” that transmit light, promoting huge, pea-soup-like algae blooms beneath the pack ice. A 2017 Science Advances article citing Frey’s research noted that such algae blooms are occurring even more frequently.

Throughout her career, Frey has received grants totaling more than $13 million. Most recently, her research has been funded as part of a four-year grant from the NASA Interdisciplinary Research in Earth Science Program; a five-year grant from the U.S. Office of Naval Research’s Arctic and Global Prediction Program; and a six-year grant from the National Science Foundation Office of Polar Programs’ Arctic Observing Network.