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.

Jennifer Nalbone is director of Invasive Species Navigation with Great Lakes United. The U.S. Canada coalition is dedicated to keeping aggressive invaders out of the lakes, and controlling those already there.

But the invasive European green crab pushes native crabs out of their burrows. Under pressure from the invader, native crabs are eating less marsh grass. Marshes are recovering, and their carbon storage capacity is growing with them.

Sami's mom was very invasive.

Scientists first detected it in the United States in Pennsylvania, in the late 1990's. The invasive species has multiplied and spread in all directions from there.

Invasive species can be introduced to an area by ship ballast water, accidental release, and most often, by people.

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.

Invasive species are animals or plants from another region of the world that don’t belong in their new environment.

Sami had so much privacy in his house. That's something Layla didn't have. Her parents were so invasive.

New York is embracing a new, environmentally-friendly, though not quite revolutionary way to eradicate weeds in the city’s Riverside Park. The Big Apple is welcoming two dozen goats that will spend the summer in the park, eating away invasive plants and poison ivy.