Download Alien Species

Invasive Species
Photo by Kara Goodwin
Changing Hudson Project
Institute of Ecosystem Studies
Definitions
• Alien: Non-native, outside its native range
– Exotic, introduced, weedy, non-indigenous
– Not normally part of ecosystem
– Established, self-sustaining population
• 10% rule
– 10% survive
– 10% become invasive
• Human activities involved
• What is an invasive species? –one that is
aggressive and threatens local biodiversity.
Changing Hudson Project
Institute of Ecosystem Studies
Why Should you be Concerned?
• 50,000 introductions to U.S.
• Cost
– $137 billion/ year in damages and pest control
costs (Pimentel, 2000)
• Impacts to native species
– Threats to 49% of all endangered and
threatened species
– Blamed for 68% of fish extinctions in U.S.
Changing Hudson Project
Institute of Ecosystem Studies
Why are Invasive Species a
Problem?
• No natural enemies
– Predators
– Competitors
– Parasites and diseases
• Populations increase rapidly
• Out compete native species for resources
Changing Hudson Project
Institute of Ecosystem Studies
Mile-a-minute
• Grows up to 6 inches per
day
• Native to Asia, brought
over by mistake in
ornamental plants in the
1930s
• Takes over open spaces,
grows over existing
vegetation
• Spikes on the vines make
it difficult to remove
Changing Hudson Project
Institute of Ecosystem Studies
Kudzu
• “the vine that ate the
South”
• Introduced from Japan in
1800s to control soil
erosion on farms
• Now entering NY
• Spreads by runners and
seeds
– 60 feet a year, 1 foot/day
– 6 inch taproot
• Smothers native species
Changing Hudson Project
Institute of Ecosystem Studies
Islands
• Islands often suffer damage-why?
-small geographic areas, lack of genetic
variability: native species
-islands tend to have fewer overall species
-rate of introduction is often higher
Changing Hudson Project
Institute of Ecosystem Studies
Galapagos Islands: Introduced Goats, Pigs,
Raspberry bushes, Rats…
Changing Hudson Project
Institute of Ecosystem Studies
Brown Tree Snake In Guam
• Native to South Pacific
• Probably stowaway in
ship cargo, 1950
• Eats small vertebrates
and bird eggs (9 of 11
native forest-dwelling bird
species extirpated; 5
extinct)
• 40 snakes/acre
• Local extinctions
• Power outages
Source: www.birdlife.org
Changing Hudson Project
Institute of Ecosystem Studies
Mongooses on Hawaii
• Native to South Asia and
Africa
• Introduced as a
biological control for rats
and snake in sugar
cane, late 1800s
• Mongooses diurnal, rats
nocturnal
• Feed on native wildlife,
decimating endemic
birds
Changing Hudson Project
Institute of Ecosystem Studies
Zebra Mussels, Dreissena
polymorpha
• Native to SE Europe
and W Asia
• Live in fresh and
brackish water
• 1985, ballast water
from European ship,
Lake St. Clair, near
Detroit
• Spread through Great
Lakes and Erie Canal
Changing Hudson Project
Institute of Ecosystem Studies
Changing Hudson Project
Institute of Ecosystem Studies
Zebra Mussels, Dreissena
polymorpha
• Life history
– Warm water, external
fertilization
– Larvae, veligers
– Settle on hard
surfaces
– Mature at one year
– Live 6 - 7 years
– Filter feeders, plankton
– Eaten by some fish,
some ducks, crayfish
and crabs
Changing Hudson Project
Institute of Ecosystem Studies
www.usgs.gov
http://www.dgif.state.va.us/zebramussels/
www.zeestop.com
Changing Hudson Project
Institute of Ecosystem Studies
A map showing the distribution of zebra mussels and quagga mussels, another
invasive. (USGS, 2007. Zebra Mussel Information: U.S. Distribution Maps,
http://nas.er.usgs.gov/zebra.mussel/).
Changing Hudson Project
Institute of Ecosystem Studies
The dotted line
shows the arrival of
the zebra mussels in
the Hudson.
Based only on this
data, what can you
say about the effects
of the invasive
mollusk on the
Hudson river?
Changing Hudson Project
Institute of Ecosystem Studies
Zebra Mussels, Dreissena
polymorpha
• Effects of the Mussels:
–
–
–
–
–
Less phytoplankton and zooplankton
Plankton-feeders declined, including fish
Water clarity and nutrient increases
Uses lots of oxygen, less fish
Economic
• Water intakes, boat hulls
• Toxic antifouling compounds
• Costs $1000,000 – 1,000,000/yr
Changing Hudson Project
Institute of Ecosystem Studies
Changing Hudson Project
Institute of Ecosystem Studies
redbreast sunfish YOY
soluble P
transparency
littoral benthos
250
200
150
100
50
0
-50
-100
dissolved oxygen
American shad (YOY)
deepwater benthos
macrozooplankton
native bivalves
microzooplankton
phytoplankton
Change associated with
zebra mussel invasion
Ecological Effects
INCREASE
DECREASE
Characteristics of Successful
Invasives
•
•
•
•
•
High reproductive rate
Long lived
Good dispersal
Adapt well to new place
Few predators
Changing Hudson Project
Institute of Ecosystem Studies
Controlling Invasive Species
• Often not possible, significant costs
• National Invasive Species Act of 1996
– For the Hudson River and Great Lakes only
– Ballast water must be treated, retained, or released in
ocean
-Inspection of goods at
customs
-Global shipping is a
problem
Changing Hudson Project
Institute of Ecosystem Studies
Ways to Eradicate
•
•
•
•
Biological Control
Chemical Control
Mechanical Control
Prevention
Changing Hudson Project
Institute of Ecosystem Studies