Risk Assessment for Invasive Species

Transcription

1 Risk Assessment for Invasive Species Reuben Keller, David Lodge Center for Aquatic Conservation University of Notre Dame Science Serving Society

2 Some Terminology Risk Analysis = Risk Assessment + Risk Management Risk Assessment is the process of determining what might happen e.g.,predicting ecological, economic, human health impacts of invasive species Risk Management is the process of deciding what to do about the risk, and doing it e.g., establish prohibited and allowed lists for plant imports Science Serving Society

3 Overview 1. Why would we want to assess risk? Aquatic Species in trade in the Great Lakes Region 2. Requirements of risk assessment 3. Three approaches to risk assessment Literature Review Quantitative Questions Statistical 4. Economic benefits from risk assessment Science Serving Society

4 Incoming Species to the Great Lakes Region Taxa Trade Pet Nursery Food Bait Bio. Supp. Total Plants Fish Mollusca Crustacea Amphibia Insecta 1 1 Annelida 2 2 Keller & Lodge 2007 BioScience

5 Benefits from Risk Assessment Programs for proactive risk assessment can reduce ecological impacts by preventing the arrival of invasive species Risk Assessment can have large economic benefits Net present value ($AUbillions) Policy time horizon 100 years 50 years 25 years 10 years Accuracy of screening tool (%) Keller, Lodge & Finnoff (2007) PNAS

6 2) Requirements of Risk Assessment 1. Accurately discriminate between high and low risk species (few grey species) 2. Be based on scientific evidence 3. Provide consistent results, regardless of the person conducting the assessment 4. Provide results quickly 5. Be well documented 6. Be proactive

7 Overview 1. Why would we want to assess risk? Aquatic Species in trade in the Great Lakes Region 2. Requirements of risk assessment 3. Three approaches to risk assessment Literature Review Quantitative Questions Statistical 4. Economic benefits from risk assessment

8 Literature Review Risk Assessment Gather information deemed appropriate and sufficient Assess risk of species to designated geographic region Example 1 Mandrak & Cudmore (2005) risk assessment for Asian carp species in Canada -Extensive biological synopsis -Previous invasions -Specific ecological and economic risks -Geography of risk -Overall project took 6-12months

9 Literature Review Risk Assessment Example 2: APHIS Risk Assessment Asks five broad questions about the risk posed by plant species Based largely on expert opinion and an unspecified amount of data gathering Response to each question is negligible, low, medium or high risk Responses combined to an overall ranking of negligible, low, medium or high risk

10 Literature Review - Pros & Cons Pros Allows RA to include any data or information deemed relevant by the assessor Cons Accuracy will depend strongly on user Likely to get different results from different users (individual bias) When should a user stop collecting data (i.e. potentially very costly)? Overall result may not be very informative

11 Quantitative Questions Risk Assessment Example: Australian Plants WRA Australian government has mandated since 1997 that all new plant species proposed for introduction to Australia be assessed and placed onto black or white lists Tested successfully around the world 49 questions, not all of which need to be answered Response to each question gets a score (usually +/-1) Sum scores for result, leads to a black, white or grey listing

12 Australian Plants WRA Category 1: Domestication/Cultivation 1.01 Is the species highly domesticated? Category 2: Climate and Distribution 2.01 Species suited to Australian climates? Category 3: Weed Elsewhere 3.01 Naturalized beyond native range? Category 4: Undesirable traits 4.06 Host for recognized pests and pathogens Category 5: Plant type 5.01 Aquatic? Category 6: Reproduction 6.02 Reproduces viable seed Category 7: Dispersal mechanisms 7.02 Propagules dispersed intentionally by people

13 Quantitative Questions: Pros and Cons Pros Consistent results Australian WRA is internationally accepted Out of the box functionality Clearly defined stopping point in search for data (usually takes 1-2 days/species) Accuracy shown to be good in a number of regions (Australia, New Zealand, Hawaii, Florida) Easy to document Cons May not identify new impacts

14 Statistical Risk Assessment Gather data for test species Use statistical tools to find patterns in data that are most strongly related to invasion For future species, full data does not need to be collected

15 Example 1: Fish in the Great Lakes Relative 2 yrs <66.5 >66.5 Number taxa in diet Minimum temperature o C <4.5 >4.5 <5.5 >5.5 Number taxa in diet SUCCESS Relative 1 yr (%) FAIL <1.5 >1.5 <26.5 >26.5 SUCCESS FAIL FAIL SUCCESS Kolar & Lodge 2002 Science

16 Example 2: Mollusks in the Great Lakes Dreissena polymorpha Pisidium henslowanum Corbicula fluminea Potamopyrgus antipodarum Bithynia tentaculata

17 Example 2: Mollusks in the Great Lakes Corbicula fluminea Dreissena polymorpha Potamopyrgus antipodarum Pisidium henslowanum Bithynia tentaculata Probability Invasive Log 10 (Annual Fecundity) Keller et al., 2007 Conservation Biology

18 Example 2: Mollusks in the Great Lakes Corbicula fluminea Dreissena polymorpha Pisidium henslowanum Probability Invasive % Probability Log 10 (Annual Fecundity) Potamopyrgus antipodarum Bithynia tentaculata Keller et al., 2007 Conservation Biology

19 Statistical Risk Assessment: Pros & Cons Pros Consistent results Clearly defined stopping point in search for data, rapid Should have high accuracy Easy to document Designed specifically for aquatic plants in Indiana Cons Requires time (=$) to put together Although accurate, may not look intuitive

20 Summary of Risk Assessment Tools Literature Review Potential to be highly accurate, but requires oversight Consistency may be low Cost may be very high Quantitative Questions Shown to be very accurate High consistency Cost is relatively low (1-2 days/species) Statistical Shown to be very accurate High consistency Lowest cost to use because few data are required Higher expertise (and potentially cost) required to assemble

21 Requirements of Risk Assessment 1. Accurately discriminate between high and low risk species (few grey species) 2. Be based on scientific evidence 3. Provide consistent results, regardless of the person conducting the assessment 4. Provide results quickly 5. Be well documented 6. Be proactive

22 The Best Approach?? All risk assessment approaches can perform well All approaches require experts, data collection, $$ Best approach would include sharing of risk assessment technology and data among assessors Regional cooperation would reduce everyone s costs, make expertise more available, and allow for regional coordination of listed species Science Serving Society