You Poured it
Where?
A Case Study in
Invasive Species
Nancy Boury
Iowa State University
Please get into groups of 3-4
students
Take 5 minutes to review your notes
on the case and the NY Times article
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What is the problem?
3
What is the problem?
• Alex is helping Jim move.
• Jim has an old, well-established saltwater aquarium
that he is tearing down for the move.
• While Jim is upstairs helping to pack his fish, Alex
starts draining the tank.
• Jim comes down and catches Alex in the act of
dipping a bucket in the tank and finds out that Alex
had planned to dump the water into a nearby storm
drain.
• Jim stops him “just in time” (or so he thinks).
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CQ#1: Jim was horrified that Alex planned to
dump the water down a storm drain because:
A. This tank had a serious fungal contamination
problem.
B. The water would enter the potable
(drinkable) water system unchanged.
C. The tank contains algae known to be
invasive.
D. The chemicals present in tank would damage
the local plant life.
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CQ#2: In your opinion, which single trait of the
Aquarium-Mediterranean strain of Caulerpa
taxifolia makes it particularly well desirable for
use in public and private saltwater aquariums?
A. Resistance to temperature
fluctuations.
B. Bright coloration.
C. Rapid reproductive rate.
D. Resistance to herbivores (it
produces toxins).
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What are some of the traits that
make Caulerpa particularly invasive?
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Aquarium-Mediterranean strain
Caulerpa taxifolia traits
• Grown in saltwater aquariums:
– How is that different from “in the wild”?
• Produces a toxin:
– What impact would this have on aquatic herbivores?
• Reproduces asexually:
– Why is this significant?
• Smallest “reproductive unit”
is a 3-5 mm fragment
– How can it spread?
Image Credit Greig Peters, Regional Water Quality Control Board, Bugwood.org
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CQ#3: An advantage of asexual reproduction
over sexual reproduction is that asexually
reproducing species generally have a ___:
A. Higher mutational frequency from parental to F1
generations.
B. Greater genetic diversity within the population.
C. Higher rate of reproduction than sexually
reproducing species.
D. Greater photosynthetic capacity.
E. Greater resistance to fungal and viral pathogens.
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Caulerpa taxifolia’s history of invasion
• Caulerpa taxifolia – Used in aquariums – discovered in 1984.
• In the late 80’s and 90’s, it expanded into the Mediterranean.
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CQ#4: The Aquarium-Mediterranean strain of
Caulerpa taxifolia is particularly invasive because:
A. It was artificially selected to possess traits favorable
to aquarium life.
B. Each outbreak of Caulerpa taxifolia is the result of
human activity.
C. It has natural predators that would normally control
its spread. Those predators are becoming
endangered species.
D. It also reproduces sexually, giving more diversity to
the population of this particular strain of Caulerpa
taxifolia.
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Why is the invasion of Caulerpa
taxifolia a problem?
Take a minute to discuss this with
your group
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CQ#5: In terms of local ecosystems, why is the
invasion of the Mediterranean strain of
Caulerpa taxifolia a problem?
A. The toxins it makes will accumulate in the top
predators due to bioamplification.
B. It is a poor food source, and herbivores will lose
their native food supply.
C. It is a clonal species, and clones are inherently
dangerous to any ecosystem.
D. It doesn’t photosynthesize, so won’t fix carbon
dioxide. Carbon dioxide levels will rise and
contribute to global warming.
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Other reasons this invasion is
detrimental?
• Replaces rich, diverse communities with a
monoculture.
• May outcompete endangered species.
• Caulerpa is a poor member of the first trophic
level because it is toxic.
• Invasions lead to alterations in the species
richness and abundance of life in the
community.
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CQ#6: A coastal lagoon reports a small (2″
square) area of Mediterranean-strain Caulerpa
taxifolia. From the list below, what is the most
likely source of this vegetation?
A. Nearby farmers producing nitrate-rich runoff.
B. Ozone depletion leading to an increase in mutation
rate.
C. Greenhouse gases changing the potential ecological
niche for the seaweed.
D. Poorly treated urban waste entering the water
supply.
E. Misuse of antibiotics to treat viral infections.
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CQ#7: Could Alex’s dumping the water from an
aquarium transfer Caulerpa to local waterways?
A. Yes, if the local
waterways are saltwater.
B. No, not even if local
waterways are saltwater.
Rachel Woodfield, Merkel & Associates, Inc., Bugwood.org
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Jim Cleans the Tank
What steps does he take?
Why?
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CQ#8: If you were Alex, would you report the
Caulerpa dumping incident to the local U.S.
Fish and Wildlife Service?
A. Yes
B. No
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Alex’s Assertion:
“It can’t happen here.”
In your group, please review the
2002 Science article about
Caulerpa taxifolia.
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Rachel Woodfield, Merkel & Associates, Inc., Bugwood.org
“California Tries to Rub out the
Monster of the Lagoon.”
By J. Withgott
Science Vol 295 March (2002)
pp. 2201-2202.
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In 2000, the Mediterranean strain of
Caulerpa taxifolia was identified in
California.
What can southern California do
about this invasive algae?
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CQ9: When Rachel Woodfield started eliminating Caulerpa
taxifolia in California, the algae occupied approximately
10,000 m2 in Huntington Harbor and 200 m2 in Agua
Hedionda Lagoon. From the graph below, predict how
much of Huntington Harbor would be covered with the
algae after two years if it was left alone.
A.
B.
C.
D.
E.
1 m2
40 m2
10,000 m2
40,000 m2
120,000 m2
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CQ#10: You are in charge of an anti-Caulerpa program in
a coastal region, what would you do FIRST to control a
small patch of the “killer seaweed” found at the bottom
of a local fishing harbor?
A.
Educate the local populace about the dangers of
Caulerpa taxifolia to the ecosystem.
B. Ban the sale and transport of Caulerpa taxifolia in the
state you live in.
C. Treat all affected areas with a bleach solution and
remove the dead flora and fauna.
D. Introduce sea slugs to the affected areas. The sea slugs
will eat the seaweed.
E. Develop safe, non-invasive alternatives to Caulerpa for
saltwater aquarium enthusiasts to use.
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What did California do?
Nova News Minute
http://www.pbs.org/wgbh/nova/minutes/i_3008.html
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The Plan Part I: Remove the Algae
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The Plan Part II: Educate the
Populace
• This is what the Southern California Caulerpa
Action Team (SCCAT) did:
– Surveys found that 52% of southern California
aquarium retailers sold Caulerpa, 95% sold “live
rock.”
– Legislation was passed that banned sale, transport
or ownership of Caulerpa.
– Educational brochures were developed.
– Collecting samples was banned.
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CQ#11: Do you think this plan was successful?
A. Yes
B. No
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Here’s what happened:
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CQ#12: If you were Alex, would you report the
incident to the local U.S Fish and Wildlife
Service?
A. Yes
B. No
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What did it take to eradicate Caulerpa
taxifolia in California?
• $7 million
• 6 years
• Early, multi-disciplinary approach
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Cost of invasive species to the U.S.
economy
• $137 billion spent each year for ALL invasive
species.
• Homeowners spend $500 million/year.
• $100 million spent to control aquatic weeds
that clog waterways.
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For Further Reading…
Killer Algae by
Alexandre Meinesz and
Daniel Simberloff,
University of Chicago
Press, 1999.
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