2. EXOTIC SPECIES
• also known as alien species, invasive
species, non-indigenous species, and
bioinvaders, are species of plants or
animals that are growing in a nonnative
environment.
3. CONTENTS:
• ECONOMIC IMPACT
• ENVIRONMENTAL IMPACT
• HOW DO THEY GET HERE?
• EXTENT OF THE PROBLEM
• WELL KNOWN INVADERS
• WHERE DO WE GO FROM HERE?
4. ENVIRONMENTAL IMPACT
• Research has shown that more than 40
percent of species on the U.S.
Department of the Interior's lists of
endangered or threatened species are
at risk primarily because of
nonindigenous species.
5. • Invading species can cause complex
changes within the structure and
function of their new ecosystem. Their
presence can lead to the restructuring
of established food webs, the
importation of new diseases to the new
surroundings, and competition with
indigenous organisms for space and
food.
6. • Other ecological changes may occur
when the invading organisms reproduce
with native species, possibly altering
the gene pool. This may lead to
hybridization and homogeneity, which
reduces biodiversity, the primary
element associated with an ecosystem's
ability to adapt to natural or human-
induced changes.
7. ECONOMIC IMPACT
• Ninety-eight percent of the food grown
in the United States come from
nonnative species of wheat, barley, rice,
cattle, and poultry.
• The nonnative honeybee is essential in
growing plant crops, as well as
generally benefiting flower pollination.
8. • The economic damage caused by rats is
huge. Rats alone do more than $19
billion of damage per year. Damage
caused by alien insects cost $20 billion.
Altogether, the more than 30,000
nonnative species in the United States
cost the country $123 billion a year in
economic losses.
9. How Do They Get Here?
• Introductions of nonnative species can
be planned, incidental, accidental, or
unintentional. They can also be caused
by a natural disaster. Scientists have
made several attempts to identify the
possible pathways of introduction, with
varied success.
10. • The most common method of
introduction into marine environments
is through the ballast water of shipping
vessels. A cargo ship floats high in the
water and is very unstable when it is
empty. To stabilize the ship, the crew
fills the ballast tanks with water. When
the tanks are filled, marine organisms
are pumped in along with the water.
11. • Then, when the ballast water is
discharged at the next port of call,
exotic species can be introduced.
Scientists estimate that as many as
3,000 alien species per day are
transported around the world in the
ballast water of ships.
12. Extent Of The Problem
• Every state in the United States and
nearly all communities have been
affected by bioinvaders. However, two
states have been especially hard hit—
Hawaii and Florida—and for similar
reasons. Both states are geographically
isolated and both have a semitropical-
to-tropical climate.
13. Hawaii
• Hawaii has been geographically isolated
from the rest of the world for millions of
years. Because of this isolation, Hawaii
originally had thousands of species that
existed nowhere else on Earth. But it
has suffered the highest rate of
extinctions of any area of the United
States and one of the highest rates
anywhere in the world.
14. • The tropical climate of Hawaii allows
invasive plants and animals to thrive.
Nonnative plants and animals frequently
displace native species. Predation by
nonnative rats, feral cats, dogs, and
mongooses has led to the extinction of
many species of birds. Habitat
destruction by feral pigs has altered
landscapes.
15. • To compound the problem, nonnative
species are usually more aggressive at
colonizing disturbed ground left behind
by the feral pigs.
16. Florida
• Like Hawaii, Florida has a subtropical-
to-tropical climate that allows many
plants and animals to thrive. The state
is protected by ocean on three sides.
On the fourth side, it is geographically
isolated from the states further north by
differences in climate.
17. • Because of this isolation, Florida is
considered to have been somewhat
species-poor, with many niches
available for invasive species to
colonize.
18. • Florida now lays claim to 63 percent of
the nonindigenous bird species, 25
percent of nonindigenous plants, 25
percent of land mammal species, and
the largest number of established
nonindigenous amphibian and reptilian
species in the United States.
19. • Overall, approximately 42 percent of
Florida's reptiles, 23 percent of its
mammals, 22 percent of its amphibians,
16 percent of its fishes, 15 percent of
its flora, and 5 percent of its birds are
naturalized nonindigenous species.
20. Philippines
• Invasive alien species like the water
hyacinth, which is native to tropical and
subtropical South America, are
considered a major driver of biodiversity
loss, as they tend to compete and
displace native species and cause
ecological imbalance.
21. • Unlike kangkong or water spinach, a
nutritious vegetable Filipinos eat, water
hyacinth is not edible and causes
adverse impact on people and the
environment. Aside from this, it can
cause flooding and affects the mobility
of people traveling via boats, including
those fishers whose livelihood is
severely affected.
23. African Clawed Frog
• The African Clawed frog was widely
used in human pregnancy testing in the
1940s and 1950s, and as a result was
shipped all over the world. The frog is
native to southern Africa, but is now
found around the world in suitable
habitats, probably due to accidental or
deliberate releases.
25. Mediterranean Gecko
• This small gecko is a native of the
Mediterranean, and apparently first
arrived in the United States on cargo
ships unloading in New Orleans. Some
areas may also have been colonized by
escaped pets. The lizard is primarily
nocturnal, preferring rocky walls near
bright lights. It is found all along the
Gulf Coast of the United States and as
far west as Arizona.
27. Zebra Mussel
• Zebra Mussels originated in
the Balkans, Poland, and areas within
the former Soviet Union. The species
was introduced into the Great Lakes in
the ballast water of ships in 1988. It
has been spread by barge traffic into all
the major East Coast rivers of the
United States that are connected
through canals to the Great Lakes.
29. Giant Toad
• The native range of the giant toad
extends from southern Texas, through
Mexico and Central America,
to Brazil in South America. This marine
toad is widespread, occurring outside its
natural range in places such
as Australia, Fiji, Guam,
Hawaii, Japan, New Guinea,
the Philippines, the Solomon Islands,
31. Where do we go from here?
• Many scientists think that the spread of
exotic species is one of the most
serious, yet largely unrecognized,
threats to our environment. Nonnative
animal species cause enormous
economic each year to crops,
waterways, and natural environments.
32. • Safeguarding our natural heritage from
alien and exotic species involves
stopping additional introductions, the
early detection and quick eradication of
pests, integrated systems for the
control and management of existing
pests, and the restoration of native
species and ecosystems.
