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| Water chestnut |
Water Chestnut Control: Start Early and Continue
by New York Sea Grant Launch Steward Nick Spera
Aquatic invasive species (AIS) in local watersheds and ecosystems are negatively impacting native plants, animals, and habitat. An invasive species is defined by the federal Executive Order No. 13112, which establishes a National Invasives Species Council, as a species that is non-native to the ecosystem of interest and whose introduction causes or is likely to cause economic or environment harm or harm to human health.
Locally, European water chestnut (WC), scientifically known as Trapa Natans, is an AIS causing problems in Oneida Lake, the Salmon and Oswego Rivers, and some embayments of Lake Ontario.
Originating from Europe, Asia and Africa, WC has made its way to North America over the years and nows grows, and often thrives, in freshwater habitats such as nutrient-rich lakes and slow moving or stagnant rivers.
Without control efforts, WC plants form dense floating mats that severely limit light and oxygen availability for native species. WC easily outcompetes native species by overcrowding to dominate waterways and increase the potential for fish die-off. Large colonies of WC also negatively affect boating, fishing, swimming and other aquatic recreation.
With such a quickly-reproducing
species, control methods can be quite difficult. If not kept in check, WC will
flourish and thrive until it clogs one area and begins to spread to surrounding
waterways.
How do we manage something
that has the ability to spread so rapidly? The answer is through concern,
persistence, and dedication. With the help of environmental professionals, communities
and volunteers come together to raise public awareness of AIS and take on the
challenge of AIS management.
Management and control methods
vary depending on the location, level of invasiveness, AIS population size, and
local conditions, such as the size of the water body and surrounding ecosystem.
Oswego County Soil and
Water Conservation District Manager John DeHollander says the goal of treatment
depends on the site characteristics and density of the WC population.
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| Water chestnut hand pull volunteer with baskets of WC removed from lake environment; photo: NYSG/Nick Spera |
Hand pulls are done with
groups of volunteers, with the goal of removing as much of the WC as possible.
Still, some plants can be left behind.
Therefore, it is more reasonable to maintain control over a smaller
infested area to prevent the WC from spreading further.
When conditions of a WC infestation
are not conducive for a hand pull, other alternatives such as mechanical and/or
chemical treatment may be considered.
Mechanical harvesting
machines cut and collect the aquatic plants, removing them from the water by a
conveyor belt system. The plant matter is then stored in the harvester until the
AIS can be removed and disposed away from water. This method works well on
large communities of WC that have spread beyond control for mechanical
harvesting.
"Speaking from
years of experience with mechanical harvesting at the same site (Ox Creek) annually
for four years, then skipping the fifth year, we saw the water chestnut move
right back in, making it look like the site had never been treated,” DeHollander
says.
Eradication is very rare,
but may be possible if the WC population is small; however, it would be
necessary to continue treatment efforts for several years.
Suppression and
containment are more reasonable goals for AIS treatment, particularly for
larger AIS populations in isolated ecosystems.
With WC being such a
rapidly spreading plant, it is sometimes necessary to control the spread of
this AIS using chemical treatment. This sort of “shock” method is used to stop
the growth and spread of the AIS so it hopefully becomes possible to regain
control of the spread. It is important for local efforts to identify WC
invasion early, so control efforts can be made early to prevent having to chemically
treat the invasive spread and risk damaging other species in the surrounding
ecosystem.
To learn more about
organizing a local resource, please reference the "Steps and Procedures to
Help Organize an Invasive Plant Removal and Disposal" online at under Fact Sheets at www.nyseagrant.org/ccdstewards.
New
York Sea Grant is working with the Oswego County Soil & Water Conservation
District (OCSWCD) and St. Lawrence-Eastern Lake Ontario Partnership for
Regional Invasive Species Management (SLELO PRISM) to help stop the spread of
aquatic invasive species. Volunteers are needed to help control WC where the
Salmon River meets Lake Ontario. A pull will be held Saturday, July 13, 8:30am-12:00pm,
at Pine
Grove State Boat Launch, 7101 State Route 3 at Port Ontario. Volunteers need to
bring their own personal floatation device and boat (kayak or canoe works
well).
For more information on protecting native habitats against
invasive threats, contact New York Sea Grant at 315-312-3042, SGOswego@cornell.edu.
To learn more about how boaters can help slow the spread of AIS, visit the NYSG Launch Steward Program Blog.
To learn more about how boaters can help slow the spread of AIS, visit the NYSG Launch Steward Program Blog.
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