Nature Notes: Long Island’s Ponds
We are in the midst of a deep drought. Yes, we had almost three inches of rain locally two Sundays ago, but a drive by Chatfield’s Hole on Two Holes of Water Road showed that it hardly made a difference. The pond level was so low, that there were two ponds, a largish one to the north, a small one to the south. The small one had a tiny island in its center covered with the northern shrub of the heath family, leatherleaf.
We have two kinds of freshwater ponds on the South Fork, ponds fed by groundwater and those filled by precipitation. The former are called water table ponds, they represent the top of the freshwater, or upper glacial, aquifer. The latter are vernal ponds, “vernal” after the Latin word “vernalis” for the season spring. They are so named because they tend to be filled in the spring, after winter’s snow and ice melts, and subsequent March and April rains.
Vernal ponds rarely have fish in them, while all natural groundwater ponds do. Fort Pond in Montauk is fed by runoff from precipitation and the underlying groundwater, principally by that running in from under Hither Hills and, to a lesser degree, by the freshwater aquifer around the Montauk Downs golf course. Groundwater ponds almost never dry up. Indeed, even after the current prolonged drought, Fort Pond is still close to its record high level achieved after the eight inches of rain that fell in March 2010, which raised the top of the aquifer several feet throughout the entire South Fork. Until it was permanently opened to Block Island Sound during the 1920s by Carl Fisher’s developers, Lake Montauk — at over 800 acres in surface area — was the largest groundwater pond on Long Island by far.
A third type of pond on Long Island is the coastal pond, such as Sagaponack Pond in Southampton Town, Georgica Pond in East Hampton Town, and Oyster Pond in Montauk. They are groundwater ponds that receive periodic inundation of tidal water from adjacent seas. Consequently, they tend to be brackish and populated by species that can tolerate a bit of saltwater from time to time.
During this ongoing drought several vernal ponds such as Daniel’s Hole pond near East Hampton Airport in Wainscott dried up completely. It was dry from November through mid-April. Only after the rains of April 22 did the pond bed receive enough water to invite the neighborhood’s spring peepers to emerge from their winter quarters. When I went by on April 24 they were singing up a storm and in full breeding frenzy. Even so, unless it ains a lot in the next few weeks all of their frenetic reproductive efforts will be to no avail.
Vernal ponds generally occupy topographical depressions, some of which are known as kettle holes, formed by melting blocks of ice left by the glacier as it melted away and retreated to the north 12,000 years ago. Scoy Pond in East Hampton’s Grace Estate is one of them. Short’s Pond on the north side of Scuttlehole Road in Bridgehampton is another, while Big Fresh Pond in Southampton’s North Sea, more a groundwater pond than a vernal one, is a third.
Chains of separated groundwater ponds situated along a roughly north-south line are found between Sag Harbor and Sagaponack, north Bridgehampton and south Bridgehampton.
The hamlet of Montauk has the most freshwater ponds and wetlands of any South Fork community. But only two are natural groundwater ponds, Fresh Pond, or Hidden Pond, in Hither Hills and Fort Pond. Yet the hamlet has loads of vernal ponds, largely because its “knob-and-kettle” topography offers a great number of depressions and its clayey soils are relatively impervious to water.
If it weren’t for Montauk’s vernal ponds, there would probably be no blue-spotted salamanders on Long Island. They breed in temporary ponds such as those in Culloden and the Sanctuary. If they were left to breed in ponds with fish and snapping turtles they would never make it, as fish are voracious predators of salamander tadpoles. Montauk’s vernal ponds also support several distinct breeding populations of the eastern newt. The vernal ponds of East Hampton’s Northwest, such as those on the Grace Estate and Camp Regis, are a godsend for the spotted salamanders in the spring, and marbled salamanders, which uniquely breed in the fall. Late summer and early fall rains are not as likely as spring rains, but apparently there are enough of them to keep the marbled salamander going.
Vernal ponds and their edges also support a great variety of freshwater wetland plants, most of which are not found on the edges of groundwater ponds. They very often have three different types of flora — aquatic plants that root in the pond bed or float on top, such as duckweed, permanent wetland plants such as red maple and tupelo trees, rushes, and sedges, and three episodic plants that only show up when the waters recede, exposing a wide, damp, muddy shelf where they can thrive.
Such is the situation these days at Chatfield’s Hole in Northwest. Rare members of the sedge family and white lance-leaved violets are becoming dominant. After sufficient rains and the filling of the pond to its pre-drought level, these plants will be submerged and become dormant and will remain quietly in the soils underwater for several years, until the next drought comes along.
Lastly, there is a variation of the vernal pond, which one might call the “very vernal pond,” as it’s more like a puddle than a pond. They pop up here and there throughout the South Fork and elsewhere on Long Island after an unusually heavy rainfall, in late May, June, July, or August. These very vernal ponds only last for a few weeks, but just long enough for the eastern spadefoot toads to dig out of the ground with a lot of grunting and groaning to find one in which to spawn.
The spadefoot is one of the few amphibians in North America specifically adapted to take advantage of such opportunities. On the other hand, Australia’s outback, which is largely arid, has several different amphibians that remain underground, sometimes for several years, until one of these rain events comes along. Then all hell breaks loose. Several frogs and toads new to science have been discovered in this way.