Bigelow Scientists Study High Arctic Food Web

Much of the fish caught in the United States comes from Alaska’s Chukchi and Bering Seas. Though crucial food sources, these ecosystems are poorly understood - and rapidly changing as sea ice retreats in response to climate change. During the summer of 2017, Senior Research Scientist Michael Lomas and Postdoctoral Scientist Steven Baer each took part in an oceanographic cruise to the Arctic designed to study the Chukchi Sea ecosystem from “end-to-end” – from the chemical composition of seawater to ecosystem impacts by humans, and everything in between.

“This is actually one of the first studies that will really help reveal the structure of this Arctic marine ecosystem,” Lomas said. “Rather than just picking one part of the ecosystem and trying to understand how it’s changing, we're measuring all the various elements of the system in order to learn how they are connected and affecting each other.”

Funded by the North Pacific Research Board, this comprehensive study is called the Arctic Integrated Ecosystem Research Program, and seeks to establish baseline information about the Northern Bering and Chukchi Seas. Understanding the processes driving the ecosystem, and how reductions in sea ice impact them, will help commercial fisheries and coastal Alaskan communities adjust as the climate continues to change.

Key to any fishery’s health is the structure and condition of the supporting ecosystem, particularly prey species. After their first field season in 2017, Lomas and his colleagues observed that the size of large plankton, like copepods, is likely much more significant than the total amount of plankton.

“Based on observations in the Bering Sea, it’s likely that we will also see these kinds of size changes among phytoplankton in the Chukchi Sea as well,” Lomas said. “These changes at the base of the food web have dramatic impacts on fisheries recruitment.”

The energy held by smaller copepods, which are important in the Bering and Chukchi Seas, doesn’t reach the fish as efficiently as energy in large copepods.

The Chukchi Sea study is also assessing range migration in Arctic fish populations, like Pacific cod, Arctic cod, and Saffron cod. These species may be moving north as those waters become more habitable, which could result in expansion of some species’ habitats.

Species higher in the food web are already being affected. Walruses are moving farther from shore as the sea ice extent shrinks, and hunters from the Arctic communities that rely on them must now travel further across open water. The lack of sea ice is also increasing seaside erosion, undercutting villages and washing away infrastructure. Even before the mechanisms of climate change are fully understood, Alaskans are being forced to change their hunting strategies and even the locations of communities.

“It is important to understand and measure what is actually changing, and not rely on preconceived notions,” Lomas said. “The Arctic is a vital and sensitive ecosystem that has far-reaching effects on the entire planet.”