Invasive Species

Canada's Royal Botanical Gardens sit near the western end of Lake Ontario, just a short drive from the U.S. border. When the weather is warm, visitors come to see acres of gardens with roses, lilacs and other collections in bloom.

In the winter, it’s much quieter. But scientists stay busy, protecting wetlands from destructive carp. And they're using an unusual weapon: Christmas trees.

Invasive plants and animals are an expensive problem in the United States -- federal agencies spent more than $104 million last year to control them.

But a recent study on invasive garlic mustard shows that it might sometimes be better to leave invasive species alone.

There’s some bad news in the Great Lakes and it’s all about the sea lamprey, an eel-like creature that literally sucks the life out of fish. They do a lot of damage and now they’re on the rise in some lakes.

That trend has stumped scientists.