Wild blue mussels were once a common sight at low tide in rocky crevices along Casco Bay. But the population seems to have disappeared in over at least the past decade.
Now scientists are enlisting the public to help them locate clutches of mussels surviving in deeper water.
Aaron Whitman with the Gulf of Maine Research Institute said predators such as invasive green crabs, a warming ocean and other factors may have pushed mussels to find shelter in the deeper subtidal zone.
"People have seen mussels disappearing from the intertidal zone, that doesn’t necessarily mean they are completely gone," Whitman said.
Blue mussels used to cover more than two-thirds of the intertidal zone in the Gulf of Maine, but are down to less than 15% of their historic habitat, according to a 2016 study published by researchers at the University of California, Irvine.
The Gulf of Maine Research Institute wants to map out what beds of mussels are still out there, but harder to see.
The organization is asking volunteers to go out at upcoming extreme low tides and photograph any mussel beds they find. Documenting where they haven't found any mussels is also important, Whitman said.
"If there's no mussels there that's also very good information so that we're not wasting our time going over and mapping out an area that doesn't have any mussels," he said.
Community members can upload photos and add notes to the institute's online hub. The data will be used to guide more thorough surveys using sonar and a remotely operated vehicle to locate and measure mussel beds.
While the small bivalves are often overlooked, they are a key indicator of a healthy ecosystem, Whitman said. As filter feeders, mussels help keep water clean, provide an important food source and create habitat for other fish, he added.
"That's the hard part, they are not a big charismatic species. So they might not get as much attention and love from the public, that doesn't mean they're not important," Whitman said.
Upcoming extreme low tides are on Jan. 10, 11, 12, and 13, then on Jan. 28 and 29.
To participate volunteers can visit the institute's ecosystem investigation network.
