Looking for life in Arctic mud

Editor's note: This is the seventh in a series Dispatches from the Arctic on the August science cruise by NOAA and partner scientists aboard the Coast Guard icebreaker Healy. Today's post is from Janet Hsiao, NOAA John Knauss Sea Grant fellow, and Meredith LaValley of the Interagency Arctic Research Policy Committee.

Seven often wet and muddy researchers can be found bundled in their orange full-body suits sifting through mud on the back deck of the Healy. They are investigating areas considered biological “hotspots” – or areas of high productivity – in the Pacific Arctic Sector, as part of a program called the Distributed Biological Observatory or DBO. The DBO grew from an international recognition that collecting standard samples by the many ships passing through the Bering Strait region could help map ecosystems in transition. On board the Healy this August, scientists are adding information to a decade’s worth of documenting how life in the sediment of the Arctic is changing as waters warm.

If you pull up a chunk of mud from the Bering or Chukchi seafloors, you will likely find an assortment of creatures such as clams, brittle stars, and worms that are sometimes as long as your forearm. These critters that live on the seafloor are fundamental to the food-web of the Bering and Chukchi Seas. Sea ducks, gray whales, walrus, and many fish rely directly them as a primary food source. In the last three to five years the organisms collected in mud samples have pointed to a changing Arctic ecosystem. The changes are likely the result of the dramatic decrease in the extent of sea ice in the Pacific Arctic region and a waterfall of effects that ice loss has on the Arctic. Seasonally warming bottom water temperatures, changes in prey or food concentration, and a northward migration of certain species are some of the changes DBO scientists have observed. “Things are happening, and they are happening fast,” said Dr. Jackie Grebmeier, one of the lead scientists for the DBO project. “Because the DBO is in place we are able to track them.”

Sampling the seafloor

Scientists lower a heavy instrument called the Van Veen Grab Sampler to the ocean floor to collect mud and sealife. The mud is then hauled up to be washed, sorted, and preserved for analysis of species. Credit: Devin Powell

Until this year, a particular species of cockle clam was consistently observed in one of the more southern biological hotspots. “Where we were pulling up twenty in previous years, this year we pulled up one,” said Christina Goethel, a doctoral student at the University of Maryland.  Scientists are not yet certain of what caused this change but it is not surprising that as the warmer waters move northward, the seafloor marine life that typically thrives in cooler waters recedes and sometimes dies. The changing ecosystem affects other organisms higher in the food chain, like walruses that eat the cockles, which eventually affects local Alaska communities that depend on subsistence foods harvested from the ocean.

Grebmeier with her colleague and husband, Dr. Lee Cooper, have conducted more than 30 years of research to ensure regular sampling of the seafloor marine life community of the Arctic. They were instrumental in establishing the DBO, which is now an international scientific program, and continue to contribute to its ever growing database of information. Recently, Cooper and Grebmeier have begun incorporating video camera technology to supplement mud sampling and are exploring ways to get help from citizen scientists to analyze the footage captured of the Arctic seafloor.  

To view a video of the Arctic seafloor ecosystem taken in 2017: https://www.youtube.com/watch?v=QGvJm1VjGrk&t=51s

For more information on the Arctic video documentation efforts by citizen scientists, please contact Dr. Lee Cooper at cooper@umces.edu