The invasive European green crab is tearing down ecosystems in Newfoundland and building them up on Cape Cod.

House cats are often invasive predators that damage the ecosystems they are introduced into.

Holding a sign that read, “Sharks are friends, not food,” Yurasits emphasized that issues about ocean health “is more than just plastic.” “It’s overfishing, climate change, invasive species and habitat loss,” he said.

The invasive reed Phragmites has been steadily overtaking a marsh scientists are studying.

Invasive species can lead to the extinction of native plants and animals, destroy biodiversity, and permanently alter habitats.

Around the world, invasive species are a major threat to many coastal ecosystems and the benefits they provide, from food to clean water. Attitudes among scientists are evolving, however, as more research demonstrates that they occasionally carry a hidden upside.

That's been devastating for fish that spend their juvenile days among the seagrass. Where the invasive crabs have moved in, the total weight of fish is down tenfold.

Thanks to modern medical methods, today someone can be operated on with minimally invasive processes.

Some 1,500 kilometers (930 miles) to the south, the same invasive crab — the European green crab — is helping New England marshes rebuild.

Invasive species can harm both the natural resources in an ecosystem as well as threaten human use of these resources.