NOAA researchers study sea ice retreat, link to harmful algal blooms

By Colin A. Warren
Last week a team of National Oceanic and Atmospheric Administration researchers arrived in Nome to launch the third year of a study that seeks to study sea ice retreat and chart phytoplankton in the northern Bering Sea. The Arctic Airborne Investigations and Research mission, AIR for short, aims to collect data that – among other research objectives - will be used to help predict harmful algal blooms, HABs for short.

The mission was led by Dr. Jiaxu Zhang and Dr. Calvin Mordy, and Dr. Mike Steele acted as the science collaborator. They soared in a highly modified DeHavilland DHC-6 300 aircraft, colloquially known as a “Twin-Otter”, which contained new technology of a hyperspectral camera, an abundance of meteorological instruments, and even a special tube for deploying cutting-edge research buoys. The Twin-Otter was painted with the slogan “Low, Slow, & Good To Go”.
The Arctic AIR team included two pilots and a mechanic with stops in Nome and Kotzebue, continuing the mission coasting above the ocean to collect data throughout the region. The team was supported behind the scenes by University of Washington’s oceanographer Dr. Jim Thomson and computer engineer, Phillip Bush, amongst others.

Originally, Dr. Zhang’s research in the area was focused on physical conditions only, such as ocean currents and temperatures. In the last two years they’ve pivoted to focus more on biology, specifically phytoplankton and algae blooms. This is in part because, during July to September 2022, the largest harmful algal bloom event ever recorded in the nation took place here, in the Bering Strait region. The size, persistence and toxicity level of that 2022 event was a serious public health and food security concern for coastal communities that rely heavily on marine subsistence foods.

The pivot to focus more on biology occurred thanks to the work of environmental planner Emma Pate of Norton Sound Health Corporation’s Office of Environmental Health and Gay Sheffield of UAF and Alaska Sea Grant, both in Nome.
NSHC and Alaska Sea Grant has supported the Arctic AIR mission to create better HAB monitoring tools.

To understand how sea ice retreat relates to phytoplankton growth, Dr. Zhang explained to the Nugget: “In a warming climate, sea ice melts earlier in the year, which can trigger earlier blooms of phytoplankton if there is enough light. These blooms are comminated by large diatoms, a type of algae that supports many marine animals. However, if the ice melts too early or if there is no ice, these important blooms might not occur at all, weakening the overall productivity of the ecosystem. Another concern with the early retreat of sea ice is that it may increase the likelihood of a strong summer bloom, including harmful algal bloom species.”
A shift in phytoplankton blooms could also change conditions to favor smaller zooplankton that would attract more marine species that live in the open water, as opposed to the bottom-dwellers that are currently most dominant.

How the research works
The hyperspectral camera that has been fitted to the Twin Otter offers a deeper understanding of phytoplankton growth by the camera’s ability to capture images across a wide range of spectrums. Different algae are different colors, and the range of the camera helps identify the plethora of different types.
The hyperspectral camera on the plane is working in conjunction with the PACE satellite recently launched by NASA that was outfitted with a technologically similar, albeit much larger, hyperspectral camera. When the satellite’s camera is obscured by clouds, which is often the case in later summer in western Alaska, the images from the plane are meant to fill in the gaps. Although the Artic AIR team finished this spring’s mission, they’ll be back in the fall for more data collection.

The other main part of the mission’s data equation is collected with the micro-swift buoys designed by Dr. Steele and Dr. Thomson. Once parachuted into the ocean, these small buoys measure the amplitude and period of waves, the surface temperature of the ocean, and its salinity. They are trying to determine which basic dynamics and thermodynamics cause the sea ice to melt. The melt is largely caused by warmth in the atmosphere and the ocean and the winds blowing the ice around. These data will help determine which of the factors are more at play. The buoys are even outfitted with satellite phones so the researchers can see the data in real-time and available on a website hosted by the team to share all their ocean data with the public.  

The Arctic AIR team hopes to “ground-truth,” or confirm, the data they collect by air with water samples taken from the area. This is done by research vessels, like the Norseman II, which is currently out at sea, or local seawater samples taken by Pate and Sheffield. In 2021 they collected surface samples and “net-tow” samples from the Nome area to determine the feasibility of a regional sampling program. Then, in 2022, as a result of the unprecedented HAB event, planning was accelerated out of concern for marine wildlife and potential harm to human health. Pate and Sheffield traveled to several regional villages to teach and promote sampling from offshore through citizen science opportunities. They target three harmful algal species for monitoring: Alexandrium catenella, pseudo-nitzschia, and dinophysis. This is all part of an effort to establish an early-warning system for subsistence harvesters who rely heavily on the marine food web.
Dr. Steele is working to improve his research buoys. He’s currently working with the Department of Energy to improve the batteries and ways to charge them. His team also recently received a grant from the National Science Foundation to develop bio-plastic made from algae. “I’d love my buoy to be deployed, and when it reaches the end of its lifetime, a whale comes along and just eats it and says, yum,” he said.

Consensus is that not enough is being done. It can often take weeks or months for toxicity results to return when Pate sends them out to a NOAA lab in South Carolina, to confirm species and elevated counts. Sheffield also must send her seawater samples to the East coast, in Massachusetts for toxin testing. Pate and Dr. Zhang expressed to the Nugget that they would like to see full lab testing capabilities set up here in Nome to better serve the region.

Dr. Zhang said that she would also like to see the Arctic AIR team come to the area three times a year; currently they only come twice. They only have funding for this year’s research and will have to work to secure the continuation of their project.
This echoes the sentiment of a NOAA paper co-authored by Sheffield last month titled “Transformative Ecological and Human Impacts from Diminished Sea Ice in the Northern Bering Sea.” The paper cited a glaring gap in monitoring, surveillance and public service for federally managed marine resources that remote communities rely on heavily for economic and subsistence purposes during a time of rapid change in the Bering Sea ecosystem.

Pate told the Nugget that she would like to see the lab testing include all types of marine animals, as opposed to other similar operations in the state which focus mainly on shellfish. This is due to the wide variety of subsistence animals harvested by locals here.


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