| Aquatic Nuisance Species are more
than just a nuisance. They can affect the natural resources of an
area in many ways, some subtle, some all too obvious. Once
introduced they can become established and extremely difficult (and
expensive) to control or
eradicate. US Fish and Wildlife Services has estimated the costs
of invasive species at over $100 billion!
Florida is uniquely susceptible to ANS because of its sub-tropical
climate and has fewer native species to compete with newcomers.
All too many newly introduced exotics thrive in Florida's vast expanses
of water. Since most exotics are from the tropical areas of the
world, they can adapt quickly with the added bonus of leaving their
natural predators many miles behind. Without freezes, or natural
enemies to control them, the aquarium pet or plant that gets discarded
today could become established tomorrow, eating or infecting its way
through the food web, altering the existing natural systems is ways that
may not be evident for years, but can eventually costing millions
of dollars to control, while causing other economic hardships such as
clogging intake pipes, choking waterways, or out competing or infecting
native commercial or sport species.
According to the USGS
Summary Report on ANS, Florida has had 122 species of fish
introduced into its waters, with 53 becoming established. Over half of these introductions
are due to the release or escape of aquarium fishes. Examples include a number of cichlid,
such as the oscar, Jack Dempsey, jewelfish, convict cichlid, Midas
cichlid, and spotted tilapia; and livebearers, such as swordtails,
platies and mollies, and armored catfishes.
Crustaceans and mollusks also bask in the warm Florida waters,
hitchhiking rides from ballast water, or crawling out of bait
buckets. While their release may have been unintentional they
continue to arrive, establishing themselves displacing natives,
biofouling, bringing parasites that can affect human health.
Plants love Florida, as its name implies: Ponce de Leon named it Pascua
Florida (feast of the flowers). USGS Nonindigenous
Aquatic Plant Distribution Information lists 60 aquatic
species. The list would be much larger but it deals with strictly
aquatic vegetation, not plants that occupy the shoreline.
A
joint project of Sea Grant and other offices of the University of
Connecticut, University of Florida, University of Minnesota, University
of Illinois, North Carolina State University and Purdue University
lists the following as the most invasive aquatic and wetland plants
which are affecting, or could affect, the United States:
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Some impacts of Aquatic
Nuisance Species
- If exotic fish survive and reproduce, they are difficult, if not
impossible to control or eradicate.
- They may cause changes in the existing aquatic community through
competition with native species or predation on them, as well as
through overcrowding or aggressive behavior.
- They may infect native fish with exotic parasites or diseases.
- An exotic may also affect the genetics of native species by
hybridizing with them.
- Sole species may pose a physical or public health threat, such as
piranhas and freshwater stingrays.
- Nonindigenous species have been recorded from nearly every aquatic
system in the United States.
- In just five years, from 1988-1993, the zebra mussel spread to
waters of 20 states. Currently they have been detected in 190 lakes
that have no connection to the Great Lakes or to inland waterways.
- Introduced through the aquarium trade to seven states, the snail, Melanoides
tuberculata, has been found carrying parasites fatal to native
fish species in Texas.
- One of the nation's top problem aquatic weeds, hydrilla, currently
infests 179 drainages in 16 states.
- More than 500 fish species have been introduced in the U.S.,
one-third are foreign, the remaining are native species transported
outside of their natural range.
Nonindigenous
species are major, but generally unrecognized, stressor of
ecosystems.
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