CES Ecological Risk Assessment & Biodiversity 2 — Questions and Answers
Question 1: In ERA, which endpoint type directly measures effects on individual organisms rather than populations or ecosystems?
- Assessment endpoint
- Measurement endpoint (Correct answer)
- Ecological endpoint
- Stressor endpoint
Correct answer: Measurement endpoint
Measurement endpoints are quantifiable ecological characteristics used to evaluate exposures and effects, measured at the individual organism level.
Question 2: The Simpson's Diversity Index (D) is calculated as D = 1 - Σ(n/N)². A value of D closer to 1 indicates:
- Low diversity with one dominant species
- High diversity with many equally abundant species (Correct answer)
- An unstable community in flux
- A monoculture ecosystem
Correct answer: High diversity with many equally abundant species
Simpson's Index approaches 1 as diversity increases, reflecting more species with more equal abundances.
Question 3: Which U.S. EPA guidance document provides the primary framework for conducting ecological risk assessments?
- CERCLA NCP Section 300.430
- EPA/630/R-95/002F (Guidelines for ERA) (Correct answer)
- 40 CFR Part 136
- EPA/540/1-89/002
Correct answer: EPA/630/R-95/002F (Guidelines for ERA)
EPA's 1998 Guidelines for Ecological Risk Assessment (EPA/630/R-95/002F) is the primary framework document for ERA in the U.S.
Question 4: A species exhibits a Type III survivorship curve. This means mortality is:
- Constant throughout life
- Highest among juveniles with survivors living long lives (Correct answer)
- Highest among older individuals
- Randomly distributed across age classes
Correct answer: Highest among juveniles with survivors living long lives
Type III survivorship curves show high early mortality (juveniles) but low mortality rates for survivors, typical of many fish, insects, and plants.
Question 5: In population viability analysis (PVA), the minimum viable population (MVP) is defined as the population size needed to ensure:
- Zero extinction probability for all time
- A 95% probability of persistence for 100 years (Correct answer)
- Sufficient genetic diversity for evolution
- Carrying capacity to be reached within one generation
Correct answer: A 95% probability of persistence for 100 years
MVP typically represents the minimum population size with a 95% chance of persistence for 100 years, accounting for demographic and environmental stochasticity.
Question 6: Which of the following best describes 'functional redundancy' in an ecosystem?
- Multiple species performing the same ecological role (Correct answer)
- Excess nutrient cycling capacity in soil microbial communities
- The duplication of food web linkages
- Resilience provided by physical habitat heterogeneity
Correct answer: Multiple species performing the same ecological role
Functional redundancy occurs when multiple species perform the same ecological function, providing insurance against species loss.
Question 7: The NOEC (No Observed Effect Concentration) in aquatic toxicity testing has been criticized primarily because:
- It is too conservative and overestimates risk
- It is statistically dependent on sample size and test variability (Correct answer)
- It cannot be determined for chronic exposures
- Regulatory agencies do not accept it as valid
Correct answer: It is statistically dependent on sample size and test variability
NOEC is the highest tested concentration showing no statistically significant effect, making it sensitive to statistical power and experimental design rather than biology.
CES Ecological Risk Assessment & Biodiversity 2
In ERA, which endpoint type directly measures effects on individual organisms rather than populations or ecosystems?