Levin: Childs Pond
Childs Pond, a small, deep, kettle hole lake in East Thetford, is the beneficiary of a block of ice that separated thousands of years ago from the retreating glacier.Like a prehistoric icehouse, the block sat buried in a depression insulated by outwash sediment, slowly melting. Eventually, the hole filled with water to become Childs Pond - close enough to throw a baseball into the Connecticut River, but in terms of hydrology, proximity is irrelevant.
The pond and the river are not on speaking terms – they don’t communicate.
A typical kettle hole, Childs Pond is replenished by groundwater and surface runoff, and by occasional seepage from nearby Conant Swamp. It has no outlet to the Connecticut River, no direct route for fish to reach it.
Mud-grubbing bullheads, whose gummy eggs stick to the feathers and legs of wading birds and waterfowl, are the only native fish in Childs Pond.
And because bullheads mostly avoid open water, from an ecological perspective for the past ten thousand years, Childs Pond has functioned as an inherently fishless lake, which has been pivotal to the evolution of its unique food web.
Mark McPeek, a biologist at Dartmouth College, says that the absence of predatory fish in Childs Pond favored a singular suite of invertebrates, where dragonfly nymphs were top predators. Here aquatic nymphs grew larger, faster and more animated than similar species from nearby Post Pond, which supports hungry, visually oriented fish.
In Childs Pond, whenever a damselfly nymph encounters a dragonfly nymph it bolts, dragonfly in hot pursuit.
Conversely, nymphs from Post Pond freeze whenever danger approaches. In other words, over deep time the presence or absence of fish shaped the behavior of aquatic invertebrates, which is why Childs Pond became a masterpiece of aquatic evolution.
To add fish would be like colorizing an Ansel Adams photograph or cleaning up Jackson Pollack’s drips.
But that’s what happened, when unbeknownst to McPeek or Vermont Fish and Wildlife, someone dumped a bucket of bass in Childs Pond - largemouth bass: voracious, relentless, invasive.
What was once an aquatic gem has been ecologically changed, degraded, it’s originality gone forever.