Transcript Invasive Species

Announcements
Oct. 4, 2006
Key on course web site (link on lectures page)
click on “Test 1 (key)” after Sept. 20
You can pick up error sheets after class today.
Invasive Species II
Lecture Objectives:
1. Be introduced to biological invasions
2. Know several examples of invasive
species
3. Learn what you can do to stop the
spread of invasive species
BBC
5 October, 2004
Deadly ladybird' sighted in UK
A ladybird which has already caused havoc to native insects
in America has been spotted near a pub in Essex. Harmonia
axyridis posed a "deadly threat" to butterflies, lacewings and
many other ladybirds. The ladybird is an Asian species
which was introduced into North America 25 years ago to
fight aphids. It has since spread to Europe and last month
was discovered in the gardens of the White Lion pub in
Sible Hedingham. It is critical to monitor this ladybird now,
before it gets out of control and starts to annihilate our own
British ladybirds. H. axyridis is still sold in North America as
a pest control. "It is now the commonest ladybird in North
America.
www1.ncdc.noaa.gov/pub/data/images/ great-lakes-ice-avhrr.gi
Laurentian Great Lakes
Mills et al. 1993
Over 140 exotic species
Many fish species
were (and continue to
be) released
intentionally
Erie
Many other exotics have entered the lake
accidentally:
Canals
Escape from captivity
Ballast water
Bait buckets, live wells and gear
Sea Lamprey
(Petromyzon marinus)
Invaded the Great Lakes after the opening of
the Welland Canal
Devastated native fish stocks, especially lake trout
Other fish (>25 species)
Alewife (1873)
(Alosa pseudoharengus)
Canals
Coho salmon (1933)
(Oncorhynchus kisutch)
Deliberate release
Round goby (1990)
(Neogobius melanostomus)
Ballast water
Chinook salmon (1873)
(Oncorhynchuys tshawytscha)
Deliberate release
Exotic Crustaceans (>6 species)
Bythotrephes cederstromi (1984)
Ballast water
Cercopagis pengoi (1998)
Ballast water
Exotic mollusks (> 14 species)
Asiatic clam (1980)
(Corbicula fluminea)
Aquarium release
Quagga mussel (1990s)
(Dreissena bugensis)
Ballast water
ZEBRA MUSSEL — Dreissena polymorpha
Found in 1988 in Lake St. Clair (Lake between Huron and
Erie, just off of Detroit, MI).
Up to 70,000 individuals per m2
Likely came to North
America in ballast water
One of the most expensive exotic species
Will biofoul and restrict the flow of water through
intake pipes (drinking, cooling, processing and
irrigating water)
Also attaches to boat hulls, docks, locks, breakwaters
and navigation aids, increasing maintenance costs
and impeding waterborne transport.
Characteristics of zebra mussels:
Can attach to hard
surfaces
They have a free-living
planktonic larval stage—
veliger
Females can produce 40,000
veligers
These are typical characteristic of marine species
Veligers are easily transported in bait buckets and
livewells and anywhere else water collects
Adults can attach to hulls and survive outside of
water for several days.
Cover most
hard surfaces
Negative effects
on native clams
Zebra mussels cover
them and prevent them
from feeding and
moving
Plants (> 59 species)
Eurasian Watermilfoil (1881)
Myriophyllum spicatum
Purple Loosestrife (early
1800s)
Lythrum salicaria
How to prevent the spread of aquatic nuisance species?
Never dump bait buckets!!
Before leaving site, inspect gear, boats and
trailers for exotics
Empty all water before leaving site
Rinse your boat and equipment with high pressure
hot water, especially if moored for more than a day
Let equipment dry for several days (does not work
for species with resting eggs)
Lake Victoria
zmax = 100m
More than 30 million
people depend on the lake
for survival
Lake Victoria Cichlids
Over 300 endemic species
described from Lake Victoria
Haplochromis obliquidens
Rock scraper
Crab eater
Plant scraper
Snail crusher
Parasite picker
Egg snatcher
Rock-reef low-foraging
zooplanktivore
Scale eater
The traditional fishery
was dominated by
hundreds of native
species.
But the
introduction of gill
nets and other
gear by the British
in the early 1900s
resulted in overfishing
In the 1950s, several new species were introduced to
Lake Victoria to compensate for the declining stock of
native species
Oreochromis niloticus
Nile tilapia
eats zooplankton
Lates niloticus
Nile perch
eats fish
One major life-history difference between the
native and exotics:
All cichlids provide parental
care
Many cichlids brood a
relatively small number (5 to
100) of large eggs
The exotics have much higher birthrates and no
parental care
Before 1980, Haplocromines contributed about 80% of
the biomass and Nile perch less than 2%
Figure from Kaufman 1992
Most rapid
vertebrate
mass
extinction in
recent history
What had been a fishery of > 400 species now was
dominated by three:
80% Nile perch
20% Nile tilapia and omena
As the native fish species declined, Nile perch shifted
to feeding on the native shrimp Cardina nilotica
Other problems with Nile
perch:
Destroys gear
Cannot be sun-dried
Can be smoked, but smoking
required wood
Favors large-scale fishing
operations, which results in
malnutrition, unemployment and
poverty
What kind of ants are “pests”
• Both native and introduced
species can become problematic
– Leaf cutting ants, “sugar ants”,
fire ants
• Most damaging species are
introduced
• Biggest problems may occur
on islands that have no native
ant species.
Why worry about introduced ants?
• Agricultural
– Some direct damage to crops
– Tend and protect aphids
– Disrupt biological control programs
• Urban pests
– Mostly nuisance but can spread bacteria (in
hospitals)
• Ecological pests - ecosystem level effects
The red imported fire ant
Why worry about introduced ants?
• Ecological pests - ecosystem level effects
Phrynosoma coronatum
Declining throughout its range.
A “sit and wait” ant specialist.
Argentine ants disrupt ant-mediated seed dispersal.
Dendromecon rigida - tree poppy (Papaveraceae)
How do we control invasive species?
• In urban and agricultural areas pesticide use
still common
• Natural enemies - Biological Control
• Manage the landscape to minimize disturbance
– Turn off the water; landscape with native
plants
Results of pesticide use
• Killed native competitors
• May select for resistance
• Health risks for people
Biological Control:
The use of one species to control another.
Usually a specialist predator or parasite of an
invasive species.
Needs to be species specific or could cause even
worse problems.
Phorid flies
Bacteria
Priorities for future research:
Comparisons of native & introduced populations
(determining native range)
More experimental, large-scale & long-term studies
Better estimates of density & biomass
Prevention & control
Prevention
•
•
•
•
•
•
Education is key
Research is still needed - generalities?
Monitoring programs - early detection
Prevent establishment - quarantine
Increased communication among agencies
Increase regulations
What can you do to stop the
spread of exotics?
http://www.invasivespecies.gov/
Points to know, Oct. 2-4
•
•
•
•
Name two reasons we should be concerned about exotic,
invasive species. How are they often introduced?
Why are some exotic species so successful? Why are
certain ecosystems more vulnerable to exotic species?
Be able to recognize the exotic species from these
lectures by name. Additionally, know the Lake Victoria
and Laurentian Great Lakes stories in detail.
Know how individual people can help prevent the spread
of invasive species.