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Oil spills can be cleaned up, but biological spills can last forever!

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:



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.

Cost to U.S. economy

  • Billions annually.
  • 79 animal and plant species, 1906 to 1991: $79 billion.
  • 15 recent introductions could cost the U.S. $134 billion by 2050.
  • Sea lamprey control costs (U.S. and Canada): >$12 million/year
  • Present worth of decreased economic value of sport and commercial fisheries in the U.S. Great Lakes attributable to a fully developed ruffe population: $119 million.
  • Annual zebra mussel control/adaptation costs incurred by major raw water users in the Great Lakes : $30 million/year




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This site was last updated on 11/05/2004