Searching for tiny clues to changing seas

Editor's note: This is the second in a series of Dispatches from the Arctic from the August science cruise by NOAA and partner scientists aboard the Coast Guard icebreaker Healy. Today's post is from Chrissy Hayes, a Knauss Fellow at NOAA’s Office of International Affairs, working with NOAA Alaska Fisheries Science Center team surveying zooplankton.

By Chrissy Hayes

The U.S. Coast Guard crew gently guides a pair of ultra-fine meshed nets, to the deck of the Healy, where they land with a slight thud. It’s almost 1 a.m. as NOAA researchers and Coast Guard technicians work together to retrieve the contents of the “bongo” nets, named for their twin circular openings that resemble bongo drums, now resting on the deck of the 420-foot Coast Guard cutter  in the Chukchi Sea. They’re collecting some of the tiniest denizens of these rich waters - zooplankton - as part of an annual mission to monitor the health of the ecosystem.

Science operations on the Healy happen around the clock while  the massive vessel glides effortlessly through the Arctic waters as the team conducts biological sampling for  the Distributed Biological Observatory (DBO)-Northern Chukchi Integrated Study (NCIS) Research Cruise. This annual cruise is an impressive scientific feat, bringing together multiple disciplines to study changes along important biological hotspots in the northern Bering and Chukchi seas.

U.S. Coast Guard crew members guide bongo nets out of the water for the zooplankton net tows aboard the cutter Healy. Photo Credit: Chrissy Hayes/NOAA.

Researchers from the NOAA Ecosystems and Fisheries Oceanography Coordinated Investigations (EcoFOCI) program, a joint program of NOAA's Pacific Marine Environonmental Lab and the Alaska Fisheries Science Center, are aboard the Healy to measure and quantify the communities of tiny zooplankton. At first glance, these zooplankton look indiscernible from the algae and jellyfish surrounding them, but a closer look reveals they are actually small invertebrates, such as Arctic krill and copepods.

These zooplankton are the building blocks of the Arctic food web, explains EcoFOCI Program Lead Janet Duffy-Anderson, of NOAA's Alaska Fisheries Science Center, adding that the abundance and structure of their communities is thought to be rapidly changing as conditions in the Arctic also change. NOAA scientists recently documented record-low winter sea ice extents in the Bering Sea region which, coupled with later freezing dates in the Chukchi Sea, might have profound impacts on the quantity and distribution of these organisms throughout the Arctic, Duffy-Anderson said. EcoFOCI is up in the Chukchi Sea to evaluate a relatively pristine, ice-dominated ecosystem, characterizing changes in environment as they occur.

Janet Duffy-Anderson,NOAA EcoFOCI Program Lead, and Knauss Fellow Chrissy Hayes rinse bongo nets for processing. Photo Credit: Lindsey Leigh Graham/NOAA

The availability of copious amounts of zooplankton rich in fatty lipids are vital for the healthy ecosystems found in the Arctic. Here in these cold waters, lipid-rich plankton are dependent on winter sea ice. Researchers have documented a decrease in some of the copepods and krill species, at the same time that winter sea ice extents in the Arctic remain at an all-time low. Typically, these high-fat individuals will feed on large-celled algae that accumulate under the ice in winter and fall out every spring when the ice melts, but what happens when there is less winter ice? If sea ice does not extend far enough, the abundance of ice-associated zooplankton will suffer. If these communities decline, species that feed on them, such as fish, seabirds, and large marine mammals, will have to expend more energy, sometimes foraging for longer and at higher energy costs for the same meal.

Below deck, the researchers evaluate the size and quantity of zooplankton in the latest trawl along the DBO-NCIS route in an attempt to answer some of these questions. Meanwhile, the midnight crew washes off the bongo nets with seawater hoses, preparing samples and getting ready to send the nets back into the Chukchi Sea.

Some time around midnight in the Chukchi Sea. Science operations on the Healy happen around the clock, thanks to the dedication of the Coast Guard Crew and scientists aboard. Photo Credit: Chrissy Hayes/NOAA

Each August, US Coast Guard Cutter Healy conducts a research cruise for the Distributed Biological Observatory, which is supported by NOAA’s Arctic Research Program. During the month-long cruise, U.S. scientists take a wide range of physical, chemical, and biological observations and measurements from eight designated hot spots in the Pacific Arctic Region. For more on the Distributed Biological Observatory, please see a special edition of the journal Deep Sea Research.