From The Boston Globe:
EARLIER THIS MONTH, a troop of volunteers in Newton piled into canoes and went to war in the name of the Charles River. They wore gloves to protect themselves from their enemy: a thorny aquatic plant called the European water chestnut, believed to have invaded the Charles a century ago after escaping from the Harvard botanical garden. The plant spread swiftly, growing so thick in some areas that it overwhelmed the waterway entirely. For the past four years, the Charles River Watershed Association has led the effort to get rid of the pest, recruiting concerned citizens to pull the unwanted plants out by their roots and collect them in plastic laundry baskets.
The European water chestnut is considered an invasive species, one of the 1,500 or so plants and animals across the United States that have ended up settling in places where they don’t belong because of human activity. It’s a dubious distinction – one that most of us associate with evil carp overpowering local fish populations in the Mississippi River Basin, stubborn zebra mussels clogging pipes and killing birds in the Great Lakes, and the Asian longhorned beetle wiping out trees here in Massachusetts. Controlling the spread of such creatures has been a priority among ecologists and conservationists since roughly the 1980s. In that time, projects like the one on the Charles have proliferated around the world, forming a movement to patrol the natural environment and protect its fragile native ecosystems from intruders. The reasons to fight invasive species may be economic, or conservationist, or just practical, but underneath all these efforts is a potent and galvanizing idea: that if we work hard enough to keep foreign species from infiltrating habitats where they might do harm, we can help nature heal from the damage we humans have done to it as a civilization.