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'Snapshot' of Barnstable Harbor's seafloor lays groundwork for climate resilience

Map of Barnstable Harbor showing sampling stations 1-31.
Center for Coastal Studies
Map of Barnstable Harbor showing sampling stations 1-31.

Scientists studying Barnstable Harbor have taken a “snapshot in time” of the seafloor to study how it is changing.

Mark Borelli, a coastal geologist at Center for Coastal Studies who oversaw project, said it’s not entirely clear how experts will use the findings of the mapping project in the future, but that’s the point.

“Once you have a dataset, you can start asking questions that you might not have even thought of asking before,” he said.

What is clear, he said, is that experts will be able to measure the impacts of future storms, pollution, sea level rise, and other impacts of climate change in the harbor, using this baseline.

“Doing this kind of work gets us away from the anecdotal. ‘I remember what this place was like when I was a kid. It's really changed. Or it's all the same.’ This gets us away from that,” he said. “It's very quantitative, it's very rigorous.”  

The project began in the spring of 2018, when the Center for Coastal Studies started taking high-resolution acoustic imagery of the seafloor and collecting sediment and tiny invertebrates at 31 unique stations across the harbor and its outer flats.

From there, the team began the arduous process of counting and identifying organisms in the samples under a microscope.

“I think it's 89 different species and ... 40,267 [individuals], to be exact,” said Agnes Mittermayr, a marine ecologist who served as the the lead author of the Barnstable Harbor report. That included worms and shellfish. 

“And I’m not talking oysters of quahogs,” she added. “I’m talking tiny, tiny, 2-3 millimeter amethyst gem clams.” 

The mapping effort also revealed debris, salt marsh erosion on the southern shore of Sandy Neck and other places, and two invasive species, the common periwinkle and a species of the skeleton shrimp.

Compared to earlier studies, scientists found an increase in species that were traditionally found in the south. It seems they’ve moved north seeking cooler waters, a common impact of climate change.

“There wasn't anything like, ‘Oh my God, the world is falling apart in our harbor,’ or anything like that,” said Avery Revere, former president of the Friends of Barnstable Harbor, who launched the effort to study the area. “It was more, ‘We just know what's there today.’”

The hope, Revere said, is to revisit the monitoring stations every 5 to 10 years and begin to study salt marsh changes more deeply.

This spring, Friends of Barnstable Harbor plans to move up the food chain to study how many commercially and recreationally important species like mussels, striped bass, and silversides are in the area.

Eve Zuckoff covers the environment and human impacts of climate change for CAI.