Gulf of Maine Study Completes 20th Year, 200th Trip

In the late 1970s, Bigelow Laboratory for Ocean Sciences founder Charles Yentsch collected oceanographic data by sampling from the MV Marine Evangeline, a ferry that ran between Nova Scotia and Maine. At the time, Barney Balch was a 16-year-old high school student working for the young laboratory, soaking up ideas about oceanography and his future career.

Today, Balch is a senior research scientist at Bigelow Laboratory, and the founder of the Gulf of Maine North Atlantic Time Series, which has run continuously since 1998. Often referred to by its acronym, GNATS has two main goals. By sampling the same locations in the Gulf over many years, Balch seeks to understand how the Gulf of Maine is changing. At the same time, he collects data used by NASA to calibrate and validate its ocean color satellites.

“The germ of the idea was planted when I was in high school,” Balch said. “I realized that the complexity of the environment was something I couldn’t truly appreciate until I got out there in a boat and went back and forth across the Gulf of Maine collecting data for decades.”

GNATS celebrated its 20th anniversary this September and completed its 200th trip from Portland, Maine, to Yarmouth, Nova Scotia. During the last 20 years, Balch has utilized the ferries that travel across the Gulf to collect data in the most cost-effective way possible. Inspired by Yentsch, GNATS has collected data from four ferries, four research vessels, and even a lobster boat captained by Collin Yentsch, Charles Yentsch’s son.

“This project wouldn’t be possible without a dedicated team here at Bigelow, the ship operators, and NASA,” Balch said. “On the boat, things have to operate like clockwork. I liken it to being a short order hamburger cook in Times Square at noon.”

Though their mission has remained constant, much has changed in the last 20 years. The primary ship Balch’s team samples from today, Bay Ferry’s The CAT, makes the trip across the Gulf about twice as fast as the Scotia Prince, the first ferry they used. The evolution of technology over the last two decades also completely transformed their computer systems, and oceanographic instrumentation has moved from analog to digital.

There has, however, been one important constant: the core team has remained unchanged. Research Associates Dave Drapeau and Bruce Bowler have worked alongside Balch for the last 20 years to keep the ambitious sampling schedule of GNATS moving like clockwork. All three of them have spent about six months of their lives in the waters between Portland and Yarmouth.

“We work really well together, and we know each other’s strengths and weaknesses,” Bowler said. “It’s pretty unique these days to find a team that’s been working together for so long.”

Back in 1997, Balch, Drapeau, and Bowler tackled the first big hurdle of GNATS together: how to transform a ferry into a research vessel. The answer came through innovation, and they built a mobile laboratory inside a shipping container. When the team heads out to sea today, the journey looks much the same as it did in the late 1990s. Once they confirm the forecast is clear enough for their optical measurements, they buy their tickets, drive their mobile laboratory to Portland and onto the ferry, and then set to work.

“The van still looks similar to when we started, even though everything inside works very differently,” said Drapeau. “There is one original pump left, which is older than all of us.”

The team averages 10 trips per year. All three of them have gone on about 140 trips apiece, accompanied by numerous technicians and postdoctoral researchers over the years. They’ve worked with three different ferry companies, become friends with crewmembers, discussed research with hundreds of passengers – and even explored their theatrical sides.

“After our equipment was set up for trips on the Scotia Prince, we’d go watch the floor show before going to bed, this kind of Broadway revue,” Drapeau said. “By the end of the year, we knew all the words, and probably could have gotten up and danced the whole routine.”

Today, the faster speed of the ferry means that they barely have time to sit down or drink a cup of coffee while they’re sampling. Their instrumentation measures over three hundred different variables continuously, and the team must maintain a rapid pace to collect samples and troubleshoot any problems that arise.

Now, they can also collect data without being at sea themselves. In 2008, the team added two autonomous gliders to the GNATS sampling program. Named Henry and Grampus, the gliders are programmed to cross the Gulf in a series of dives, gathering data from points deeper in the water than the team can reach from a speeding ferry.

Together, these methods create a vast dataset that has allowed Balch to draw conclusions about how the Gulf of Maine’s temperature, salinity, and more have changed over the last two decades. He has extended it even further by incorporating measurements collected by Yentsch and even Henry Bigelow, who collected ocean color measurements as far back as 1912. By adding historical data, the resulting dataset has enabled Balch to analyze trends over the last century.

“It has been incredibly rewarding to build this time series,” Balch said. “Our entire view of the Gulf of Maine has changed because of GNATS.”