Water Chestnut (Trapa natans)

(Click on the photo for a larger image.)

Readers may be unaware of this suffocating invasive, but Water Chestnut is quickly taking over selected ponds and lakes in Morris County as well as many locations in the northeastern United States.

This is not the same Water Chestnut used in Asian-style cuisine. This is a plant, that if gone unchecked, could become the aquatic equivalent of Kudzu. Read on.

Here is a brief history of the plant in New England, quoted from the Invasive Plant Atlas of New England web site:

“Sometime before 1879, Trapa natans was intentionally planted by a gardener at the Cambridge botanical garden in Fresh Pond, Cambridge, MA. This gardener reported planting it in other ponds as well. It was also distributed up to Concord, MA, where it was planted in a pond near the Sudbury River. By 1899, it was extremely invasive in the pond and the river, and needed to be pulled out. There is an 1859 record from Concord, MA, but notes on the specimen and from the New England Botanical Club indicate that this date is in error, and that it was actually from 1879. By 1920, Trapa natans had reached western Massachusetts. Since then, it has spread into Lake Champlain in Vermont, the Nashua River in New Hampshire (1998) and most recently the Connecticut River in Connecticut in 1999. Any area that is downstream of these incursion sites is threatened.”

It has spread into New York, New Jersey, Delaware and elsewhere. As the above photo from Speedwell Lake shows, Trapa natans becomes a thick mat, blanketing the surface of an entire body of water, sucking the oxygen and nutrients from the water and suffocating any other vegetation in its domain. The mats it creates severely limits light penetrating the water creating a negative effect for the health of the aquatic ecosystem.

Speedwell Lake in Morristown is a dammed section of the Whippany River. It has historical significance as well. Alfred Vail ran an ironworks here in the 19th century. It was at his homestead, part of what is now Speedwell Village, that Vail and Samuel Morse first demonstrated the electric telegraph.

Of course, since Speedwell Lake is part of the Whippany River, seed pods from this invasive can travel downstream. The Whippany River merges with the Rockaway River in Parsippany, soon connecting with the Passaic River, etc.

Most of Speedwell Lake is now covered with Water Chestnut. As far as this observer can remember, this has occurred in the past five years or less.

Lake Musconetcong has been fighting this invasive plant with hand-pulling events and special dredging machines. Lake Hopatcong has alerted the populace to be aware of this invader. Both of these locations are lake communities with many watchful eyes and dedicated volunteers working to rid their waters of Water Chestnut.

What about the hidden ponds and out-of-the way lakes? Melanie Lane Wetlands, a productive waterfowl, shorebird, heron and egret spot, but known to only a few people, is currently obliterated with Water Chestnut as well as being walled in by a state highway on one side and an office complex including a professional soccer team’s practice facility, on the other. Coincidence or not, it is an offshoot of the Whippany River downstream from Speedwell Lake in Morristown.

The photo below shows the current state of what was once referred to as Melanie Lane Pond. Most of the Water Chestnut coverage has occurred in the past two to three years illustrating how quickly this plant can dominate a body of water.

The larger lake at the Lincoln Park Gravel Pits is undergoing the same calamity. Only local residents and fishermen, a small hunt club and a very few birders know of this location. It is private property and doubtful the owner knows of, or has any interest in, managing the Water Chestnut invasion.

How do birds fare with the green mat? Some do quite well based on recent observations. Last summer, the Little Blue Herons and Green Herons of Lincoln Park and Melanie Lane feasted on the frogs and other creatures that use the Water Chestnut mat for their own purpose.

Wood Ducks seem to feel comfortable with Water Chestnut especially when the young ducklings use the vast mat for cover. Double-crested Cormorants will feed anywhere.

One species that seems to be a constant at the Morris County Water Chestnut locations is the Cedar Waxwing as they have taken a considerable liking to the floating mats. Each location that this observer has visited has had up to 15 Cedar Waxwings catching insects off of the leaves. Red-winged Blackbirds, Swallow spp. and other species typical to a swamp/marsh habitat are utilizing the source.

And, of course, certain mammals enjoy the endless aquatic salad bar, as well. Three other deer nearby were also enjoying the invasive repast when the following photo was shot. What is not illustrated by these photographs is the cumulative negative effect this plant has on the entire ecosystem.

Advertising animal adjustments to a new habitat does not intend to minimize the Water Chestnut issue. It is becoming a larger problem year-by-year and needs to be monitored and mitigated.

Report sightings of Water Chestnut to the following Rutgers contact:

Rutgers Cooperative Extension of Morris County

Here is a quick guide to the invasion, written by the NJ Water Chestnut Task Force in 2010:

Water Chestnut: An Emerging Aquatic Invasive Species in New Jersey

Here is another sobering thought. The U.S. Fish and Wildlife’s Conservation in a Changing Climate states that southern plants may soon migrate north. Kudzu cannot tolerate winter frosts. But if those northeastern winters change for the warmer, even by a few degrees… (If the reader is unfamiliar with Kudzu in the southeastern United States, perform an Internet search to get a taste of the devastation a single plant species can cause).

View local eBird checklists in the mocosocoBirds region via eBird’s Region Explorer. Use the following links:

The eBird Hotspot Primer is here and can also be accessed via the Hotspot menu item on the mocosocoBirds.com website.

@mocosocoBirds at Twitter is another communications stream. Instant field reports and links of interest are tweeted throughout the day. The latest tweets appear on the sidebar of this page. One can follow mocosocoBirds at Twitter or link to @mocosocoBirds.

Finis