英语时差：海洋最需

Don: Today, on A Moment of Science, the Ocean's Most Wanted. Sure, they might seem innocent and downright lovely in your aquarium, but released into the wild, your plants and fish can knock aquatic ecosystems right out of balance. Today's invasive species: the water hyacinth.

Ya?l: Don, aren't you being a little melodramatic?

D: Not at all. Native to the Amazon basin, but considered an ornamental aquarium plant, the water hyacinth was introduced to Florida in 1884. By the mid-1950s, water hyacinths were clogging Florida's water ways and interfering with navigation, not to mention displacing the native species. Clean up took millions of dollars, and they're still spreading on every continent except Antarctica.

Y: Hmm! that is a sad story.

D: And here's the thing. Guess how many of the species on the International Union for the Conservation of Nature's list of the one-hundred worst invasive sp