CFP Ecosystem Restoration 3 — Questions and Answers
Question 1: Passive restoration relies on which fundamental ecological process to recover degraded fish habitat?
- Mechanical grading of the streambed
- Natural recovery following stressor removal (Correct answer)
- Stocking of non-native predators
- Chemical treatment of invasive macrophytes
Correct answer: Natural recovery following stressor removal
Passive restoration removes the disturbance and allows natural succession and self-organization to rebuild ecosystem structure.
Question 2: In lake restoration, hypolimnetic oxygenation is used primarily to:
- Increase surface water temperature
- Restore dissolved oxygen in deep water and reduce internal phosphorus loading (Correct answer)
- Prevent thermocline development
- Stimulate algal bloom formation
Correct answer: Restore dissolved oxygen in deep water and reduce internal phosphorus loading
Hypolimnetic oxygenation replenishes oxygen in deep anoxic layers, suppressing phosphorus release from sediments.
Question 3: Which invasive species removal technique is most appropriate for eradicating brook trout from a high-elevation lake to restore native cutthroat trout?
- Electrofishing removal only
- Piscicide application (rotenone or antimycin A) followed by native restocking (Correct answer)
- Introducing northern pike as a biocontrol agent
- Drawdown during summer to desiccate all fish
Correct answer: Piscicide application (rotenone or antimycin A) followed by native restocking
Piscicide application reliably eliminates non-native trout, and native cutthroat restocking restores the original species assemblage.
Question 4: Channel incision in an urban stream most directly degrades fish habitat by:
- Increasing hyporheic flow and groundwater exchange
- Lowering the water table and disconnecting the floodplain (Correct answer)
- Raising baseflow temperatures
- Promoting pool formation
Correct answer: Lowering the water table and disconnecting the floodplain
Channel incision lowers the bed elevation, disconnecting floodplains and reducing groundwater exchange that moderates temperature and baseflow.
Question 5: The concept of 'river continuum' is important to restoration planning because it highlights:
- The need to restore isolated reaches without regard to upstream conditions
- How biological communities change predictably from headwaters to lowland reaches (Correct answer)
- The dominance of autochthonous production in headwater streams
- That riparian inputs are unimportant in mid-order streams
Correct answer: How biological communities change predictably from headwaters to lowland reaches
The River Continuum Concept describes longitudinal shifts in energy sources and biological communities, informing reach-appropriate restoration strategies.
Question 6: Which action would most likely reduce summer thermal stress for coldwater fish species in a degraded stream?
- Removing beaver dams
- Planting native riparian tree species to increase canopy shade (Correct answer)
- Replacing cobble substrate with fine gravel
- Installing gabion baskets in the active channel
Correct answer: Planting native riparian tree species to increase canopy shade
Riparian canopy shade reduces direct solar radiation, lowering summer water temperatures for thermally sensitive species like trout.
Question 7: A restored wetland's function as a fish nursery habitat depends most critically on:
- Permanent deep-water zones exceeding 3 meters
- Seasonal hydrologic connectivity with adjacent stream or river channels (Correct answer)
- Low emergent vegetation density
- Absence of waterfowl species
Correct answer: Seasonal hydrologic connectivity with adjacent stream or river channels
Seasonal hydrologic connectivity allows fish to access wetland nursery areas during high water and return to the main channel as waters recede.
CFP Ecosystem Restoration 3
Passive restoration relies on which fundamental ecological process to recover degraded fish habitat?