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 Water hyacinth has been described as “the world’s worst aquatic
weed,” lovely in the garden, but a nuisance in the river, according
to Andy Casper, director of the Illinois River Biological Station of
the Illinois Natural History Survey (INHS), Prairie Research
Institute, University of Illinois. At this time of year, the plant
can be spread easily.
“Water hyacinth is the aquatic version of kudzu,” Casper said. “It
grows faster than any other plant competing with it, quickly taking
over a pond or river-bed.”
As the plant spreads out over a water surface, it blocks the sun, so
native plants can’t survive. Fish that once hid amongst the
underwater plants to hunt for their prey and young fish that hide
from predators experience a changed habitat.
Additionally, in the fall as the water hyacinth dies, it sinks to
the river bottom, decomposes, taking the oxygen out of the water in
the process. Too little oxygen can lead to large fish kills in the
winter when oxygen is naturally in short supply.
 Deliberately dumping water hyacinth plants in the waterways will
cause the plant to spread, as well as composting plants too close to
a river, stream, or drainage ditch. Backyard flooding can also cause
the invasive plant to spread into nearby surface water areas.
In one case in which plants spread, an individual composted water
hyacinth plants on a pile at the edge of a yard located close to the
river. The result was a big pile of water hyacinth down river,
Casper said.
“All it takes is one good growing season, and the plants take over,”
he said.
In a survey of the entire Illinois River from Hennepin, IL to
Joliet, IL by airplane and boat, INHS staff discovered 15 individual
water hyacinth beds in the river. In addition, fish surveys also
showed that whole water hyacinth seeds were present in the digestive
tracts of carp, indicating a threat of dispersal of the seeds to
other areas. Seeds were present in 27 percent of the digestive
tracts of the common carp examined, regardless of their proximity to
water hyacinth beds.
For proper disposal of water hyacinth, place plants in a plastic
garbage bag and throw them away. Keep all plant parts away from
waterbodies because the seeds are tiny and can be missed by the
naked eye.
Water hyacinth is an economically important plant for the water
gardening industry. For this reason, the sale of water hyacinth has
not yet been prohibited by the State of Illinois, as the debate
continues on whether it survives a cold winter, according to Pat
Charlebois, INHS aquatic ecologist. Many states, and the City of
Chicago have prohibited the sale of this plant.
 Water hyacinth is just one of many invasive aquatic plants that
should not be discarded in waterways. Hydrilla, a formerly common
aquarium plant, is another plant that carries a financial toll when
it spreads uncontrolled. Plants such as these clog waterways,
impeding boat navigation. With government cleanup, millions of
dollars may be spent, and recreational areas may be closed, reducing
recreation-based incomes. [to top of second
column] |
“Hydrilla is such an aggressive plant and spreads so quickly that it can take
years to completely remove it in lakes and rivers,” Charlebois said. “Because of
this, the State of Illinois has an early detection and rapid response plan in
place in case hydrilla shows up in an area.”
Charlebois and colleague Greg Hitzroth, INHS outreach specialist, are seeking to
change the behavior of people who purchase and use plants for outdoor water
gardens and indoor aquariums, encouraging them to dispose of all aquatic plants
in sealed plastic bags in the trash. Consumers can find a list of Illinois’
invasive plants at
http://www .takeaim.org/files/8914/4225/6456/IL_consumer_2-28-146.pdf.
The State of Illinois regulates some plants, but others, which are not
regulated, can be just as much of a nuisance.
Consumers often look to retailers for advice on which plants to purchase and how
to care for and dispose of them.
“We partner with retailers, educating them not only on which species should not
be sold, but also giving them alternatives,” Hitzroth said. “We have had success
with this effort because most retailers want to do the right thing.”
There’s a loophole in these efforts, though. “A huge market for aquatic plants
is offered for sale online, which can be difficult to regulate,” Charlebois
said. “This is a sticky wicket because retailers in another state may not know
which plants cannot be sold or shipped to customers in Illinois.”
Charlebois and Hitzroth have been working with wholesalers, retailers,
scientists, hobbyists, consumers, and others and attending hobbyists’ tradeshows
to create outreach material that aims to prevent the spread of aquatic invaders
in trade. They also worked on a statewide campaign about invasive species. Part
of that effort is the Release Zero campaign, which aims to provide suggested
alternatives to release plants based on published guidelines for teachers and
water garden hobbyists from the Aquatic Nuisance Species Task Force (ANSTF).
More information about aquatic invaders in the market place (AIM) can be found
at TakeAIM.org. Alternatives to the release of aquatics in trade can be found at
ReleaseZero.org.
[Lisa A. Sheppard]
About the Prairie Research Institute:
The Prairie Research Institute (PRI) at the University of Illinois
at Urbana-Champaign comprises the Illinois Natural History Survey,
Illinois State Archaeological Survey, Illinois State Geological
Survey, Illinois State Water Survey, and Illinois Sustainable
Technology Center. PRI provides objective natural and cultural
resource expertise, data, research, service, and solutions for
decision making, the stewardship of Illinois’ resources, and the
public good.
www.prairie.illinois.edu
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