European green crab have been eating their way up the coast, feeding on clams, oysters, mussels, small fish — but perhaps most alarming is their tendency to destroy ecologically vital eel grass in the process.
Eel grass serves as a nursery for more many important commercial marine species, as well as for a number of species at risk. Without the eel grass, these lush estuaries become underwater deserts and that can have a huge impact on species that rely on it.
Eel grass meadows are also important for filtering and trapping sediment, improving water quality and helping sustain migratory waterfowl, according to the NCC.
The conservancy hopes the survey of more than 445 hectares of the Pugwash River Estuary will give conservationists a better idea of the amount and the health of eel grass beds in the area.
Craig Smith, program manager for the Nature Conservancy of Canada, said the project is designed to help track how eel grass is surviving against an "increasing and significant threat."
"Eel-grass meadows are one of the most productive ecosystems in the world," said Smith.
"Their slippery, grass like leaves provide numerous benefits to coastal environments and we are creating a baseline dataset of eel-grass in the estuary to help detect future changes."
Alien green crab, which likely originated in the Mediterranean, were first introduced to New Jersey in 1817. By the 1950s, green crab had found their way north to waters off southern Nova Scotia.
In recent years, they have rapidly expanded their range around Cape Breton, north to Prince Edward Island the Magdalen Islands of Quebec and into even colder waters around Newfoundland.