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NOAA Ship Oscar Dyson alongside an ice chunk in the Bering Sea to collect ice samples.
Credit: CO Carl Rhodes
This spring, scientists aboard the annual NOAA EcoFOCI Mooring Cruise, collected nine sea ice samples to assess the sea-ice algae community in the Bering Sea. The PMEL Ocean Molecular Ecology (OME) group will extract and sequence these samples, alongside open water environmental DNA samples, to examine the differences between ice algae communities and open water communities. This work will enhance our understanding of the role ice algae play in the ecosystem after the winter sea ice melts.
As part of the ongoing collaboration between OME and Ecosystem and Fisheries Oceanography Coordinated Investigations (EcoFOCI), Han Weinrich joined the annual mooring cruise on the NOAA Ship Oscar Dyson. The cruise departed from Kodiak, Alaska, and traveled through the Aleutian Islands into the Bering Sea, continuing north toward the edge of the seasonal Arctic sea ice. Each spring, the winter's sea-ice sheet melts and broken floes remain into the spring season, creating a dynamic, nutrient-rich environment that contributes to this biologically diverse ecosystem. The melting sea ice conditions offer scientists a valuable opportunity to study how this melting sea ice interacts with the surrounding ocean. During the cruise, the team sought out the ice edge and collected samples from three ice floes. In addition, at more than 70 sites, water column samples were collected using a CTD Niskin array for nutrients and other oceanographic parameters. This includes the collection of 180+ open ocean water samples filtered for eDNA.
Ice algae are microscopic algae that develop both inside the small water pockets of frozen sea ice and grow along the bottom of the ice. These communities, often dominated by diatoms, serve as primary producers and play a critical role at the base of the food web, supporting everything from invertebrates to marine mammals. While melting ice releases algae into the surrounding water and can be captured through standard eDNA sampling efforts, sampling the ice directly provides a detailed sampling of the ice algae communities. The presence of sea ice in the region provided the team with the unique opportunity to complete this work. To collect these ice samples, the NOAA Ship Oscar Dyson carefully navigated alongside small ice chunks. Using long poles, the science team and deck crew broke off chunks of the ice, secured them in a net, and brought them on board. The team then worked diligently to sample each chunk before setting the ice aside to melt so eDNA filtering could occur. The team gained considerable knowledge while troubleshooting this methodology, including the fact that some larger samples take over 25+ hours to melt!
In total, nine melted ice samples from three ice floes were successfully collected. These melted ice samples will allow us to discover more about Bering Sea ice algae diversity and the impact these communities have on the marine food web.
