Transcript Chapter 12: Predation, Risk Assessment and Management of

Chapter 12: Predation, Risk
Assessment and Management of
Species Invasions
By Nicole Cardona and Ruth Singer
Explanation vs. Prediction
Explanation:
Statements about what has already occurred
Prediction:
Statements about the likelihood that events will occur
Is it more important to generate predictions or explanations?
Should we place more emphasis on what we think will occur,
or should we concentrate on the past to help us predict the
future?
Risk Assessment:
Government Protocols
WRA (Weed Risk Assessment)
• evaluate risk of importing plant species through 49
questions answered with yes or no
• questions based on “weedy” attributes from 3 areas
• biogeography- distribution, climate, domestication, and
previous establishment success
• undesirable attributes- toxicity, unpalatable, and ability
to establish within native plant communities
• biology/ecology- attributes that would allow a plant to
reproduce, spread, and persist
Risk Assessment:
Quantitative Tools
• Rejmanek & Richardson (1996)- pine species in N. Hemisphere
• 12 with known instances of invasion, 12 non-invaders
• used DFA- Discriminant Function Analysis to determine
which 10 life history characteristics had the biggest influence
on the categorization
• 3 most important characteristics:
• mean seed mass
• minimum juvenile period
• interval between large seed crops
Does it surprise you that these are the 3 most important
characteristics? Why do you think height was not as important?
Risk Assessment:
Quantitative Tools
• Ricciardi & Rasmussen (1998)- aquatic invaders,
Great Lakes
• 3 step “low-cost screening profile”
1) Identify potential donor regions
2) Select potential invader with biological criteria
3) Narrow down list using prior invasion success
The authors said that Ricciardi & Rasmussen’s method
involved using list traits that had been previously put
together to narrow down the potential invaders.
Do you think using previous lists takes away from the
effectiveness of the program?
Risk Assessment:
Stage-specific approaches
• Marchetti et al. (2004)• Documented presence/absence of every non-native fish
inhabiting each watershed across CA
• Found 8 species-level characteristics for all fishes, determined
which characteristics were important to each stage of invasion
• Species establishment- all 8 equally important
• Spread- physiological tolerance and prop pressure
• Intergration/impact- prior invasion success & prop
pressure
Does it surprise you that prior invasion success was only important
at the integration/impact stage? Why do you think propagule
pressure remained important for the last 2 stages?
Is this data conclusive?
Why do you think there is
so much variation in the
data for some of the
categories and not others?
Ecological niche modeling
Peterson and Vieglais (2001)
• utilized complex informatics algorithm to quantify a
species’ ecological niche based on its native range
• used the niche’s biophysical properties (elevation, rainfall,
temperature) to project that model onto other, possibly
suitable landscapes
• lots of time needed to gather data and make models, lack
of native species occurrence data
How can you explain the
discrepancy between the
predicted location and
where the Himalayan
bushclover was actually
found in the US?
What do you think about the
success of this model?
Prevention of Accidental
Introduction
•Ballast Water Exchange (BWE)
• Mid-ocean exchange of ballast water
• Based on the idea that coastal aquatics could not
survive if release in the middle of the ocean, vice versa
• Turns out ballast organism diversity increases after BWE
• Alternative treatments to ballast water
• intensive filtration, thermal treatment, biocide
treatment, ultraviolet light control, nitrogen gas
Prevention of
Purposeful Introductions
• top-down regulation will not work as well
• need to educate people in the provider industries
Removal and Management
• Early detection
• best to look at previous performances after introduction
in previous places
• ideally have a cross-agency database to help with this
•Eradication
• manual removal, trapping, chemicals
•concept of brute force
•Control
• Herbicides, manual removal, grazing regimes
• Bio-control
In the process of early detection, it is often researchers
who are discovering non-native in a new area.
Is it the scientist’s responsibility to alert the proper
authorities? Or is publishing a paper with their findings
all they have to do?
What are the ethical boundaries when it
comes to eradication?
How do you balance the cost against the benefits
of sufficient control/eradication? Is there a point in
management when its just too expensive?
With the current economy, it is likely that less money will
be available for invasive species control and prevention.
Do you think this economy will increase the number of
invasive species?
Guilty until proven innocent?
or
Innocent until proven guilty?