Biodiversity wanes in New York

Throttling invasive species by TJ Sinnott

Bulwark for the Great Lakes and Hudson River by P Gerrity

Stopping ballast water "stowaways" by D Pughiuc

Biological pollutants in the Great Lakes by EL Mills, KT Holeck

Water quality signatures and the zebra mussel invasion by DA Matthews, SW Effler

Zebra mussel population dynamics: Implications for water quality modeling by CL Lange, DR Opdyke, JC Powers

Bad seeds: an introduction to invasive plants by AD Halpern, CA Boesse, AE Altor

You can help stop the plant invasion

President's message by D Ellis

Executive director's message by P Cerro-Reehil

People and places

NYWEA calendar

Sponsors at 73d Annual Meeting

Spring 2001 — Vol. 31, No. 1


You can help stop the plant invasion


Individuals throughout New York State can promote biodiversity and hinder the dissemination of nuisance plants by preventing their spread. And, by identifying the invasives, New Yorkers can also assist NYSDEC in limiting their distribution.


The best way to deal with nuisance aquatic species is to prevent their introduction. Although species can be transported by natural processes like wind and water movement, humans have been the primary agent in the damaging spread of many exotic plants and animals. Preventative measures that everyone should follow are:

— Remove all plant fragments from all water activity equipment especially boats, trailers, and hitches before leaving.
— Drain all bait buckets, bilge water, and live wells before leaving. Don't transport water from one area to another, even if you're moving to another section of the same water body.
— Don't discard any aquarium plants or animals into any natural waters.


You may come across invasives such as Eurasian milfoil, water chestnut, curly leaf pondweed, fanwort, and hydrilla, stream. They are most likely to be found near boat launch sites, inlets and outlets, areas of eroded soils, and shoreline construction sites. If you find a suspected plant:

  1. Collect a sample of the entire plant (including flowers, roots and all leaves).
  2. Place it between two sheets of newspaper.
  3. Place the newspaper between two pieces of cardboard.
  4. Mail the specimen with the a completed sample form to the NYSDEC Lake Services Section, 50 Wolf Road, Albany, NY 12233.

Once your specimen is identified, the Lake Services Section will provide more information about the plant and any appropriate control strategies and techniques.

Specific plants

Map updated February 2001

Eurasian watermilfoil (species name Myriophyllum spicatum) Description: Native to Europe and Asia, this submersed plant has reddish-brown to purple stems with olive green leaves in whorls (rings) of 3-6. The leaves are usually more than 1 cm apart on the stem and have 6-16 dissected segments on each side causing them to look like weather-beaten feathers. The ends of the leaves appear to have been "clipped" and shoots near the water surface are often reddish. This perennial roots in the bottom mud and can grow to lengths of 20 ft.
Habitat and distribution: Eurasian milfoil grows in fresh to brackish (slightly salty) waters and can be found in water up to 30 ft deep. Currently, it is found through the U.S., Europe, and Asia. In recent years, the presence of this exotic species has been confirmed in most counties in New York State, including 113 lakes. Since reproduction occurs by seed or fragmentation, it can by easily transported by people particularly by boats and trailers.
Importance: As with all other aquatic plants, Eurasian milfoil offers some benefits. It shelters aquatic insects, presents hiding and spawning areas for amphibians and fish, and provides some food for waterfowl. However, these short-term benefits lead to long-term problems. Thick growth affects fish and native plant growth, interfere with navigation and fishing, and causes an unattractive appearance on the water surface.

Map updated February 2001

Water chestnut (species name Trapa natans) Description: Also native to Europe and Asia, it was introduced to Collins Lake, NY in 1884 for its ornamental appearance. The attractive water chestnut is an emersed (floating) annual which can grow up to 16 ft long. It has two types of leaves: lower, submersed leaves which are feather-like and floating leaves which are triangular and toothed. The leaf stalks of the floating leaves commonly form rosettes and flowers of four white petals bloom normally in July. The water chestnut generates highly productive, thorny seeds that can ultimately grow to yield 300 new seeds within a year. Reproduction occurs by these seeds but is also possible by fragmentation of the rosettes.
Habitat and distribution: Preferring habitats with organic, muddy bottoms, the water chestnut has spread through the lakes, ponds, canals, and sluggish rivers of the Northeastern states and is continuing to expand its range. It can commonly be found in the Hudson and Mohawk River systems and has been verified to exist in more than a dozen New York counties.
Importance: The nut is edible by humans but is not a common food source for wildlife. In fact, it generally out-competes other submersed vegetation which waterfowl prefer thus endangering feeding and wintering grounds for many ducks. By providing shelter for aquatic insects and young fish, it does have some benefits. By creating large mats in the summer and fall, water chestnut hinders boating, prevents fishing, and once again alters the natural ecosystem.

Map updated February 2001

Curlyleaf pondweed (species name Potamogeton crispus) Description: This exotic submersed perennial has reddish-green leaves which appear distinctly wavy along the margin. They are finely toothed, oblong, and normally 8 cm long and 1 cm wide. Generally, its flattened, reddish-brown stems grows from 1 to 3 ft long. It can reproduce by seed but the main method of new growth is from winter buds called turions. With its growth cycle beginning underneath the ice, Curly leaf pondweed is one of the first nuisance aquatic plants to appear in the spring.
Habitat and distribution: Originally introduced from Europe to the Northeastern United States, it is now found in lakes, ponds, and streams throughout North America. It has been confirmed to exist in 21 New York counties and is continuing to spread.
Importance: Although it offers some food for waterfowl and the common benefits associated with aquatic plants, curlyleaf pondweed has the potential of dominating freshwaters in the spring and continuing to cause problems throughout the summer and fall. By dying off in early summer, the dead plants drop to the bottom and begin to decay. This process consumes precious oxygen from the water leaving less available to other organisms like fish. If there is an abundant amount of decomposing plants present and too much oxygen is removed from the water, fish kills are possible. Likewise, the decaying matter adds nutrients to the ecosystem providing "food" for algal blooms later in the season.

Fanwort (species name Cabomba carolina)
Description: Introduced to the wild as a discarded aquarium plant, fanwort has a slender stem with a gelatinous slime and fan-like leaves. It is a submersed herb with two types of leaves. The submersed green leaves are opposite or whorled and look like the general shape of a fan. The few floating leaves are alternate, linear, and 1-2 cm long. Small whitish flowers with a pink tinge bloom in fall and reproduction can occur by seed and fragmentation.
Habitat and distribution: Fanwort is frequently found in acid lakes, ponds, and quiet streams. Normally found in water 3 to 10 ft deep, it can grow up to 20 ft long surviving in water 30 ft deep. It is most abundant in the Southeastern U.S., but it has been found in shallow lakes on Long Island and acidic lakes in the Catskills. Recently, fanwort has been identified in Saratoga County creating concern for its spread into the upstate region.
Importance: Fanwort appears to be less aggressive than other nuisances aquatic plants. Based on occurrences reported in New York lakes, the presence of fanwort has not had any major effect on water-related activities. However, in other states it has been known to clog drainage canals and freshwater streams preventing water flow and recreational activities. It does offer habitat and shelter for aquatic organisms and provides some food for waterfowl.

Hydrilla (Hydrilla verticillatum):
Description: Originating from Africa and introduced as an aquarium plant, this highly tolerant submersed plant has long branching stems which fragment and create large floating mats. The green leaves are usually in whorls of 3 to 5 and are sharply toothed with red veins. They are harsh in texture with spines on the underside of the middle vein. With numerous ways of reproducing, hydrilla, can survive drought and cold winters—an advantage over native aquatic plants.
Habitat and distribution: Found mostly in the South, hydrilla can be found in rivers, streams, lakes, and ponds with varying water quality conditions. It can tolerate water that is clear to turbid (murky), slightly acidic to alkaline, shallow to deep, fresh to brackish. Hydrilla requires only low light to survive, therefore growing at greater depths and darker waters than native plants.
Importance: Currently hydrilla is not considered a nuisance species in New York but it has interfered with fisheries, water flow, and boating in other areas of the world. Since it is most commonly spread by fragments attached to boating equipment, it has the potential of easily invading New York waters.
Information furnished by Scott A. Kishbaugh, PE, Environmental Engineer II, Lake Services Section, NYSDEC. Phone 518-457-0734.
Source: NYSDEC Lake Services Section, “Common nuisance aquatic plants in New York State,” August 1997. Maps updated February 2001.


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