In early June, I found myself unexpectedly traipsing through the Scarborough Marsh — the largest contiguous salt marsh in the state — with a backpack full of fish. Our mission was to think like blue crabs as we scouted habitable locations to deploy traps.

Few associate blue crabs with Maine — they’re far more common in the estuarine waters of the Chesapeake Bay, and a popular crustacean for mid-Atlantic summer feasts. But in recent years, likely spurred by the rapidly warming waters in the Gulf of Maine, there have been increased reports of blue crab sightings in Maine waters.

As an education and communications intern for the Scarborough Land Trust this summer, I was surprised to discover that one of my responsibilities was to support a blue crab monitoring project. The project, funded in part by the Sage Foundation and led by Steven Jury, a professor at St. Joseph’s College of Maine, aims to map the presence of blue crabs in the Scarborough Marsh.

As we made our way through the marsh, we periodically tested the water temperature and salinity until we identified blue crab-worthy trap sites. Jury would then tie a sailor’s knot, place a stake through the loop in the trap rope and mark each herring-filled trap with an orange flag. The traps became a site of anticipation as we pulled them from the muck each week wondering what we might find.

In recent years, after blue crabs began making surprise appearances in lobster traps, researchers became interested in better understanding where these crabs were being spotted.

To gather location data, Jessie Batchelder, fisheries project manager for the environmental nonprofit Manomet, developed a GIS crowdsourcing map that allowed beachgoers, fishermen and boaters to report blue crab sightings. As the community site caught on, reports of blue crabs became more frequent, especially in marshy habitats known to have abundant food supplies.

Laura Crane, a research associate for the Wells National Estuarine Research Reserve, has been monitoring the influx of blue crabs while studying how they interact with their environment. “I’m interested in understanding the impacts blue crabs will have on local Gulf of Maine ecosystems, including both native and invasive species,” she said.

Crane is particularly focused on how they might affect other crustacean populations. Blue crabs are known to be ferocious consumers that have the potential to prey on juvenile lobsters, invasive green crabs and even smaller blue crabs.

While some are concerned about the potential impacts of blue crabs on the lobster fishery, Jury noted that their preferred habitats do not fully overlap. “Lobsters, while found in estuaries, are not truly estuary-dependent like blue crabs,” he said.

Meanwhile, others are excited to learn about blue crabs’ appetite for invasive green crabs, although blue crab numbers are currently too small to have a significant impact. “If blue crab populations grow, it would be interesting to see if there are any shifts in green crab populations in areas where blue crabs are more prevalent,” said Crane.

With over 3,000 acres of protected marshland, Scarborough Marsh provides excellent opportunities for these types of research and education efforts.

Land trusts play a vital role in preserving our biodiverse open space from being developed, granting us opportunities to challenge our curiosity and better understand the world around us. Without efforts to conserve and steward these important salt marsh ecosystems, studying ecological changes like the emerging presence of blue crabs would be much harder.

Since June, we have deployed six crab traps throughout the Scarborough Marsh. Every Wednesday, we check and rebait the traps, which has become one of my favorite activities. Romping into the marsh in tall rain boots has granted me more intimate access into this diverse habitat, and I’ve enjoyed spotting red-winged blackbirds, egrets and even a coyote. As someone with no prior experience in marine biology field work, I would never have dreamed that I’d one day be documenting the coordinates of crab traps in a fishy notebook.

The blue crab monitoring projects led by Jury, Crane, Batchelder and others along the coast will aid in gaining a better understanding of where blue crabs reside in Maine and how their populations are changing over time. It will also help determine how they might interact with other ecologically and commercially important species in Maine.

“Nature Connects” is a monthly column showcasing conservation stories from people and organizations across Maine. To learn more or suggest story ideas, email [email protected].