Waterwheels: Endangered or Invasive?
Waterwheels are small, rootless, aquatic plants that are also carnivorous- kind of like an underwater Venus Flytrap. In much of their native habitat, which is quickly disappearing, they are very much endangered. But here in the US, where they were introduced from Japan in the 1970s, they are invasives that pose a serious threat to native aquatic animals and plants.
This poses a real conundrum for scientists.
“It was never native here, it’s exotic,” said Steve Young, chief botanist of the New York Natural Heritage Program, a branch of state government that promotes conservation. “And it’s acting like an invasive.”
It’s concerning when a nonnative plant immediately thrives, he added, even when, as in the waterwheel’s case, there’s no direct evidence yet of it crowding out native species or posing other economic, ecological or health risks.
But some botanists who don’t want the carnivorous plant to disappear see the Northeast’s waterwheels as a glimmer of hope for the species’ global survival — or at least a buffer against its extinction.
Once waterwheel is entrenched, management options are limited. While it can be hand-collected, just one or two individuals can seed an entire population. The alternative is an herbicide that kills every plant in the area.
With few practical options for limiting the waterwheel's spread, experts have suggested the plant should remain monitored, but mostly left alone.
What should not happen again, according to Eric Lamont of the Long Island Botanical Society, are campaigns to introduce plants into environments where they did not evolve — however well intentioned.
“You don’t want to just willy-nilly introduce it to areas,” he said. “This is not the way to try to save a species.”