Somewhere in the annual reports of most lake associations and river coalitions you’ll find something about vegetation that shouldn’t be in local waters.
The word is invasives. They can be a real nuisance. Take water chestnuts -- a nonnative plant that creates mats on the surface of waters to the effect of crowding out native plants, depriving fish of oxygen and spoiling canoe rides.
Water chestnuts aren’t the only invaders of local waters, as the sign to the right, near the water in Brattleboro, Vermont, makes clear.
But they’re worth a study if only to show how such invasions happen. Water chestnuts, native to Europe and Africa, where parasites keep them in check, got to North America in the 1870s. Among other things, they were introduced to the botanical gardens at Harvard, and then they got planted in some local ponds, exotic things that they were. Then, as happens, escape! They’re a common scourge now.
I was introduced to invasives during the course of researching “Water Connections.” Among other things, I found myself reading “The Ecology of Invasions by Animals and Plants,” by the British zoologist Charles S. Elton, first published in 1958. The book is absorbing. It tells sobering stories about how plant and animal invasions are wrought by humans -- sometimes intentionally and sometimes not.
Equally interesting is what humans are doing in response.
And two years later Vermont’s Act 67 became law; the Vermont Aquatic Invasive Species Transport Law sets forth a wide range of steps that boat-owners must take to assure that they aren’t carrying invasives from one body of water to another.
So, there have been some success stories in the fight against aquatic invasives. Those stories are rare, but let’s take heart. Heightened attention to the problem is helping make a difference, meaning: we need not be victims of our own carelessness about what gets into local waters.