quiz 3

Q: What was the main question of the coho salmon study?

A: Do certain ecosystems/habitats better support salmon recovery and growth?

Q: What were the two most important habitat characteristics emphasized in the lecture?

A: Productive and diverse habitats.

Q: What is meant by a “productive” ecosystem?

A: An ecosystem with high food availability and high biological production.

Q: Why are estuaries and lagoons important habitats?

A: They are highly productive and provide abundant food/resources for fish.

Q: What are examples of physical habitat variables for salmon?

A: Stream structure, dissolved oxygen, pool depth, velocity, temperature, riparian vegetation, and instream flow.

Q: What does IFIM stand for?

A: Instream Flow Incremental Methodology.

Q: What does IFIM mainly focus on?

A: Physical habitat conditions like flow depth and velocity.

Q: What criticism was made about traditional habitat management?

A: It focuses too much on physical habitat and ignores food webs/prey availability.

Q: According to Wipfli and Baxter (2011), why do management programs often fail?

A: They don’t consider food webs and processes regulating food abundance for fish.

Q: Why is food especially important in warmer water?

A: Fish metabolism speeds up in warm water, so they need more food/energy.

Q: What happens to fish metabolism as temperature increases?

A: Metabolism increases and fish require more energy to survive and grow.

Q: Why can warm water become stressful for fish?

A: High metabolism increases energy demands and physiological stress.

Q: What is metabolic compensation?

A: Fish compensating for higher temperatures by consuming more food/energy.

Q: How could food availability buffer climate change effects?

A: More food may help fish survive warmer temperatures by supporting higher metabolic demands.

Q: Why are spring-fed systems productive?

A: They have stable flow, nutrients, prey availability, and productive food webs.

Q: Why can salmon grow well in warm spring-fed systems?

A: Food availability is high enough to support their faster metabolism.

Q: Why are most streams oligotrophic?

A: They naturally have low nutrient and food availability.

Q: What does oligotrophic mean?

A: Low nutrients and low productivity/food availability.

Q: What combination produced the highest growth rates?

A: Moderate-warm temperatures with high prey availability.

Q: What happened to fish growth in cold, low-food habitats?

A: Growth rates were much slower.

Q: What was one of the major conclusions of the study?

A: Food availability may be more important than temperature alone.

Q: What is the bioenergetics equation?

A: Growth = Inputs − Outputs.

Q: In the bioenergetics equation, what does “input” mainly mean?

A: Food consumption.

Q: What do “outputs” represent in bioenergetics?

A: Energy lost through metabolism, waste, and activity.

Q: Why was prey availability called the “forgotten half” of the equation?

A: Studies often focus on temperature instead of food availability.

Q: Which river type had higher invertebrate prey density?

A: Spring-fed rivers.

Q: Why do spring-fed systems support more prey?

A: Stable flows and nutrients support productive food webs.

Q: Why does prey density matter for salmon growth?

A: More prey provides more energy for growth and metabolism.

Q: How does this study change the way we think about temperature limits for salmon?

A: Warm temperatures may be less harmful if food availability is high enough.

A: Warm temperatures may be less harmful if food availability is high enough.

A: Temperature alone doesn’t explain growth—food webs and productivity matter too.

Q: What was the main “take-home message” from the lecture?

Food webs are extremely important and productive/diverse habitats are critical for salmon recovery.

Q: Why are productive habitats important under climate change?

A: They may allow fish to metabolically compensate for warming temperatures.

Q: What is a floodplain?

A: An area periodically flooded by lateral flow during high discharge events.

Q: Why are floodplains important ecosystems?

A: They support high biodiversity and high food availability.

Q: Why do floodplains have high productivity?

A: They have warmer water, longer water residence time, shallow depths, and lots of nutrients/light.

Q: What are autotrophic pathways?

A: Food production through photosynthesis (plants/algae).

Q: What are heterotrophic pathways?

A: Food webs based on consuming organic matter/detritus.

Q: Why are floodplains important for fish?

A: They provide spawning, rearing, feeding, and growth habitat.

Q: What fish species were highlighted as floodplain-associated fishes?

A: Splittail, Chinook salmon, Delta smelt, Sacramento perch, white sturgeon, and blackfish.

Q: What is the portfolio effect?

A: Diversity within a species buffers populations against environmental variability.

Q: What kinds of diversity contribute to the portfolio effect?

A: Phenotypic diversity and life history diversity.

Q: Why is the portfolio effect called a “portfolio”?

A: Like financial investments, diversity spreads risk so one bad event doesn’t wipe everything out.

Q: How does life history diversity increase resilience?

A: Different strategies respond differently to disturbances, so some individuals survive changing conditions.

Q: What is life history diversity?

A: Variation in traits like migration timing, spawning timing, growth, or habitat use within a species.

Q: Why is life history diversity important for salmon?

A: It stabilizes populations and helps them survive environmental change.

vQ: What happens when populations become homogenized?

A: They lose adaptability and become more vulnerable to change/extinction.

Q: How do dams affect fish populations?

A: They block habitat, reduce diversity, and fragment populations.

Q: How do levees affect floodplains?

A: They disconnect rivers from floodplains and eliminate important habitat.

Q: What is lateral connectivity?

A: The connection between rivers and floodplains during flooding.

Q: Why is lateral connectivity important?

A: It allows movement of nutrients, carbon, organisms, and energy between river and floodplain systems.

Q: What does channelization do to rivers?

A: Simplifies channels and reduces habitat diversity.

Q: What do hatcheries contribute to homogenization?

A: Reduced genetic and life history diversity.

Q: What is the Flood Pulse Concept?

A: Periodic flooding connects rivers and floodplains, driving productivity and biodiversity.

Q: What happens during a flood pulse?

A: Nutrients, carbon, and organisms move between river and floodplain habitats.

Q: How does flooding affect productivity?

A: It increases primary and secondary production.

Q: What are resource subsidies?

A: Nutrients/food transferred from floodplains back into the main river.

Q: Why do fish grow faster on floodplains than rivers?

A: Floodplains have warmer water and more food availability.

Q: Why is faster fish growth important?

A: Larger fish survive better and are more resilient.

Q: What percentage of native California fishes are extinct or declining?

A: About 83%.

Q: What percentage of salmonids may be extirpated by 2100?

A: About 74%.

Q: What does “extirpated” mean?

A: Locally extinct from a region.

Q: What is reconciliation ecology?

A: Modifying human-dominated landscapes to support biodiversity.

Q: How can rice fields act like floodplains?

A: Flooded rice fields can mimic floodplain habitat for salmon and other species.

Q: How do restored floodplains strengthen the portfolio effect?

A: They support more life history diversity and habitat diversity.

Q: What is the connection between floodplains and the portfolio effect?

A: Floodplains create diverse habitats that support many life history strategies, increasing resilience.

Q: What is the major ecological problem in California rivers today?

A: Habitat loss and homogenization caused by dams, levees, hatcheries, and agriculture.

Q: How do floodplains support biodiversity?

A: They increase habitat complexity, food availability, and spawning/rearing habitat.

Q: What happens when floodplains are disconnected from rivers?

A: Reduced biodiversity, lower resilience, and loss of life history diversity.

Q: Why are salmon considered vulnerable when floodplain habitat is lost?

A: Loss of habitat reduces diversity and weakens the portfolio effect.

Q: Why are aquatic insects often used to measure biodiversity?

A: They are numerous, diverse, have quick life cycles, and are good experimental units.

Q: What is species richness?

A: The number of different species in an ecosystem.

Q: What is resilience in ecology?

A: The ability of a system to recover after a disturbance.

Q: What is disturbance?

: A discrete event that disrupts ecosystem/community structure and changes resources, substrate, or the physical environment.

Q: What makes an event a disturbance instead of normal variation?

A: It falls outside the system’s predictable/acceptable range (ex: >2 SD above the mean).

Q: What are examples of stream disturbances?

A: Floods, droughts, wildfire, disease outbreaks, substrate movement, and high flow events.

vQ: What happens to biodiversity right after a high-flow event?

A: Biodiversity decreases because only resistant organisms survive.

Q: What does a high-flow event do to the stream system physically?

A: It “sweeps” or cleans the system, moving debris and nutrients through it.

Q: Why can biodiversity become high later after a disturbance?

A: Competition is temporarily reduced, allowing many species to recolonize.

Q: Why are disturbances sometimes called an “ecological reset”?

A: They remove dominant organisms and reset competition/community structure.

Q: What does the equilibrium model say controls diversity?

A: Biotic interactions (especially competition) control community structure, with little environmental influence.

vQ: What does the dynamic equilibrium model say?

A: Diversity is controlled by a balance between competitors and colonizers, mediated by disturbance.

Q: What is the intermediate disturbance hypothesis (IDH)?

A: Diversity is highest at intermediate levels of disturbance because both colonizers and competitors can coexist.

Q: Why does very low disturbance reduce diversity?

A: Strong competitors dominate and exclude other species.

Q: Why does very high disturbance reduce diversity?

A: Only fast colonizers or disturbance-tolerant species survive.

Q: At intermediate disturbance, who wins?

vA: Neither group fully wins—colonizers and competitors coexist, producing highest diversity.

Q: What are characteristics of colonizers?

A: Short life cycles, rapid development, many offspring, reproduce quickly.

Q: What are characteristics of competitors?

A: Long life cycles, competitively dominant, long-lived.

Q: Which organisms dominate in highly disturbed runoff streams?

Colonizers

Q: Which organisms dominate in stable spring-fed streams?

Competitors

Q: Why can competitors dominate in stable systems?

A: Predictable conditions allow long-term competition and resource control.

Q: Why do colonizers dominate disturbed systems?

A: They reproduce quickly and recover fast after disturbance.

Q: Why is predictability important for adaptation?

A: Organisms can only evolve adaptations if disturbances occur in somewhat predictable ways.

Q: What three choices do organisms have regarding disturbance?

A: Avoid, adapt, or exploit the disturbance.

Q: What factors shape adaptations to natural flow regimes?

A: Frequency, magnitude, and predictability of disturbances.

Q: What is the “cost-benefit ratio” of adaptations?

A: Adaptations are maintained only if their survival benefits outweigh their costs.

Q: What does a spring-fed river hydrograph look like?

A: Stable discharge with little variation over time.

Q: What type of diversity model best fits spring-fed rivers?

A: Equilibrium model.

Q: What does a runoff river hydrograph look like?

A: Highly variable discharge with large peaks after rain/snowmelt.

Q: What type of diversity model best fits runoff rivers?

A: Dynamic equilibrium/intermediate disturbance model.

Q: On an intermediate disturbance graph, what happens at LOW disturbance?

A: Competitors dominate; diversity is lower.