Scientists Prepare for the Next Era of Gulf of Maine Time Series

Scientists Prepare for the Next Era of Gulf of Maine Time Series

For over 20 years, Bigelow Laboratory's Gulf of Maine North Atlantic Time Series has been an essential tool for capturing vital information on the Gulf and validating satellite-based measurements of ocean color with on-the-water observations. For the last several years, though, the pandemic and funding changes have put the future of GNATS - and the valuable dataset it provides - in question. Until now.

Senior Research Scientist Catherine Mitchell was recently awarded funding from NASA to restart regular GNATS research cruises, beginning next year. The updated program will take advantage of Bigelow Laboratory's new research vessel, the R/V Bowditch, which was acquired in 2022 to enhance this kind of local research.

In August, the team took out the Bowditch for their first "shakedown" cruise, setting the stage for an exciting few years of research into the optical properties and biological communities of the dynamic and rapidly changing Gulf of Maine.

"Things have been so much harder to plan in recent years, but with the Bowditch, we're going to have the flexibility again we need to run this program," Mitchell said. "What we found on the test run is that we have some work to do to streamline our system, but it's an exciting opportunity to incorporate new equipment to advance the program as a whole."

GNATS was started in 1998 by Senior Research Scientist Barney Balch. Several times a year, a team of scientists led by Balch traversed an established transect across the Gulf aboard various "ships of opportunity," including the commercial ferry from Portland, Maine, to Yarmouth, Nova Scotia. Funded by NASA primarily to validate and calibrate satellite data, the team collected lots of information, such as nutrient and carbon concentrations, optical properties like ocean color, and details on the biological communities at the base of the food web.

When the ferry stopped running in 2018, the team had to adapt, piecing together funding for sporadic cruises as part of larger research projects. The new NASA grant Mitchell secured will allow the team to return to normalcy, with funding for eight cruises a year through 2027. Most will take place between the spring and fall to maximize daylight hours and good conditions, but they plan to be on the water year-round.

Sunny weather - which is never a guarantee on the Maine Coast - is essential for GNATS cruises so that the team's measurements can be effectively compared with satellite data. The R/V Bowditch will provide the flexibility needed to adapt to the forecast, and Mitchell said that Bigelow Laboratory's access to its own, in-house research vessel was key to the success of the revamped funding proposal.

Of course, the shift from the commercial ferry and larger vessels in the intervening years to the 48-foot Bowditch, requires some adjustments, but it also has advantages.

"We don't have to load up our mobile laboratory and drive to some far away port anymore," Mitchell said. "Now we can literally just drive down the hill to our dock. It makes it much easier to quickly jump on the boat and go when the conditions are right."

The new set up is also inspiring them to rethink some of the science in a way that could benefit the program in the long run, from increasing the number of samples they collect to recoding the software used to operate on-board instruments.

They're also making several tweaks that, Mitchell says, which will make GNATS more "PACE friendly," referring to NASA's latest ocean color satellite, which launched this year and provides an unprecedented level of information on the global ocean. Mitchell plans to shift the sampling strategy slightly to focus on measurements tied explicitly to the exciting avenues of science PACE enables and to take advantage of the latest in advanced optical equipment. For example, a new sensor will allow them to break down the total of how much light is absorbed by seawater into individual measurements for absorption by phytoplankton, inorganic material, and organic material.

Despite the changes, though, GNATS continues to be driven by many of the same questions that inspired Balch to start the program. As if to reflect that continuity, Bruce Bower and Jelena Godrijan, two researchers previously involved with the program under Balch's leadership, came back specifically to help out on the shakedown cruise.

And most importantly, GNATS will continue to be an invaluable tool for asking broad questions about the dynamic past, present, and future of the Gulf.

"One of the things I'm excited about is getting more collaborators involved in the program," Mitchell said. "If we can create opportunities for other scientists to take advantage of the fact that we're already out there measuring these things, that would do wonders to advance the science of the Gulf of Maine."

Photo 1: The R/V Bowditch, docked at Bigelow Laboratory, is being adapting for use as part of the GNATS program to monitor changing conditions and validate satellite data in the Gulf of Maine. The instrument on the front is the radiometer the team uses to measure ocean color.

Photo 2: Senior Research Associate Dave Drapeau prepares the Bowditch before a shakedown cruise in August to test new instruments and protocols before beginning official data collection for GNATS in 2025.

Photo 3: The research team managing GNATS now includes Research Associate Sunny Pinkham (left) and Research Technician Brynn Presler-Marshall (right). On the shakedown cruise in August, the team was joined by former Bigelow Laboratory staff who were previously involved the program including Bruce Bowler (center).

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