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The Invasive
Species Working Group (ISWG) is
composed of 13 representatives from
9 Florida state agencies and 1 Florida
university. Their objective is to develop
a statewide strategic plan for managing
and preventing invasive species in Florida.
The ISWG defines an
invasive species as a non-indigenous
species that has the ability to establish
self-sustaining, expanding, free-living
populations, and may cause economic
and/or environmental harm as measured
by risk assessment(s) accepted by the
ISWG.
Similarly, the
National Invasive Species Information
Center (NISIC) defines an invasive
species as
1) nonnative to the ecosystem under
consideration and
2) whose introduction causes or is likely
to cause economic or environmental harm
or harm to human health.
The NISIC states that
invasive species can be plants, animals,
and other organisms (such as microbes),
and that human actions are the primary
means of invasive species introductions.
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Cuban treefrog
photo by Kevin Enge/FWC |
A nonnative species could become
invasive soon after becoming established, like
the Cuban tree frog. It was introduced a century
ago through packing materials, and has invaded
Florida's natural areas, preying on our native
tree frogs. Cuban tree frogs rapidly spread
in south Florida and were common throughout
most of the state by the 1970's.
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Iguana photo by
Kevin Enge/FWC
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On the other hand, it might
take years for the right factors to fall into
place to allow a species to expand its range
and cause ecological problems. For example,
green iguanas have resided in Florida since
the 1960's, but their population has increased
greatly since Hurricane Andrew. Although
green iguanas have not had ecological impacts,
this Central and South American lizard causes
significant economic damage to landscape plants,
primarily in Miami-Dade and Broward Counties.
On Florida's west coast, black spinytail iguanas
have reached such abundance that many residents
view them as a nuisance, and the town of Boca
Grande has considered hiring trappers to remove
them.
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Nutria photo
by US Fish and Wildlife Service
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Some invasive animals do not
cause problems in all areas. The nutria, a large
rodent from South America, lives in warm, marshy
areas. It is abundant in the lowlands of Louisiana
and Mississippi, but Florida populations have
not been very successful even though Florida
has similar habitats to other Gulf Coast states.
