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MAR 349 > Food Webs and Fisheries > Flashcards

Food Webs and Fisheries Flashcards

(56 cards)

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1
Q

What makes up the base of the food chain?

A

Autotrophs

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2
Q

What are chemoautotrophs?

A

Produce energy using chemical sources (ex: N-fixing bacteria)

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3
Q

What are photoautotrophs?

A

Produce energy using light (ex: phytoplankton)

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4
Q

What is the 1/10 prey to predator size framework?

A

A predator is typically 10x the size of its prey

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5
Q

How does the 1/10 prey to predator framework effect food web/chain efficiency?

A
  • In ecosystems where the primary producers are smaller (ex: open ocean) more trophic transfers are needed to reach apex predators
  • In ecosystems where the primary producers are larger (ex: upwelling areas) there are fewer trophic transfers needed to reach apex predators
    This is because only __% of energy is transferred between trophic levels
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6
Q

What happens to abundance and biomass as trophic levels increase in a food pyramid?

A

Abundance and biomass decrease

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7
Q

What determines the total number of trophic levels in an energy pyramid?

A

Ecological efficiency

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8
Q

What is ecological efficiency?

A

The amount of energy available to be passed to the next trophic level/the amount of energy received from the trophic level below

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9
Q

What is the 10% rule

A

10% of ecological efficiency is passed between trophic levels

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10
Q

What are some drivers of the 10% rule?

A

Trophic level 1:
- Amount of phytoplankton
Trophic level 2:
- Amount grazed by herbivores (loss by excretion)
- Amount assimilated (loss by respiration)
- Amount available for growth (loss by non-trophic growth)
- Amount of herbivores
Trophic 3:
- Amount of carnivores

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11
Q

What is growth efficiency?

A

The portion of consumed biomass converted to new biomass rather than lost to other processes such as respiration or excretion

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12
Q

What is production?

A

The generation of biomass

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13
Q

What is food web/chain efficiency?

A

The ratio between the production of the highest trophic level to basal production (lowest trophic level)

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14
Q

How do food web/chain efficiencies vary?

A
  • By ecosystem (ex: upwelling vs. coastal vs. open ocean)
  • By food web/chain length (longer the food chain = less efficient)
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15
Q

What are some factors that affects food web/chain efficiency?

A
  • Microbial recycling: will affect how much productivity moves up the food chain vs. how much gets trapped in the microbial food web
  • Decomposition
  • Bacterial lysis and leakage of DOM
  • Cannibalism: slows transfer of energy up the food chain by keeping production within intermediate trophic levels
  • Immigration or emigration
  • Burial of sinking particles: removes primary productivity from moving up the food chain
  • The size of primary produces: larger = shorter food chain = more efficient
  • Predator prey dynamics: search time, handling time etc.
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16
Q

Describe a high productivity food chain?

A
  • High nutrients
  • Large phytoplankton
  • Fewer links
  • More productive
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17
Q

Describe a low productivity food chain?

A
  • Low nutrients
  • Small phytoplankton
  • More links
  • Less productive
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18
Q

What is fishery production?

A

The amount of harvestable biomass in a specific area

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19
Q

What will increase fishery production? A higher or lower starting level of primary production?

A
  • A higher starting level
  • This means a larger base to support more biomass at the top of the food web
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20
Q

What ecosystems have the highest and lowest fishery production and why?

A
  • Highest fishery production: upwelling ecosystems because of high primary productivity, high transfer efficiency, short food chains
  • Lowest fishery production: open ocean because of low primary productivity, low ecological efficiency, long food chains
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21
Q

Will the following scenarios increase or decrease fisheries production and why?

  1. The primary producers decrease in size
  2. The number of trophic transfers increases
  3. Nutrient availability increases
  4. Ecological efficiency decreases
  5. Immigration increases
  6. Cannibalism increases
  7. Another secondary consumer not linked to the top trophic level is introduced
A
  1. Decrease: according to the 1/10 framework there will need to be more trophic transfers necessary to reach apex predators
  2. Decrease: according to the 10% rule less ecological efficiency is being passed to each trophic level
  3. Increase: allows for larger phytoplankton to grow potentially decreasing the number of trophic transfers necessary to reach apex predators
  4. Decrease: this will decrease the amount of available energy that can be transferred to the next trophic level
  5. Increase: you are brining in outside production
  6. Decrease: ecological efficiency is slowed down by keeping production in intermediate trophic levels
  7. Decrease: increases number of trophic transfers necessary to reach apex predators
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22
Q

What are fisheries?

A

An area where fish are caught for commercial or recreational purposes (this includes rules that govern what you are doing)

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23
Q

How are fisheries managed?

Study These Flashcards
A
  1. Area of water
  2. Species/type of fish
  3. People involved
  4. Gear involved/method of fishing
  5. Class of boats
  6. Purpose of activities
24
Q

What is a population?

Study These Flashcards
A

All individuals of a single species living in the same area at the same time (biological unit)

25
What is a stock?
A management unit grouped by genetic relationship, geographic distribution, and/or movement patterns *A single population can be broken into multiple stocks*
26
Describe fish life history
- Eggs - Larvae - Juvenile - Maturing adults - Spawning adults (can occur multiple times)
27
What is diadromy?
Migration between fresh water and salt water
28
What is catadromy?
Fish that live in freshwater and migrate to saltwater to spawn
29
What is anadromy?
Fish that live in saltwater and migrate to freshwater to spawn
30
What determines sex changes in fish?
Temperature
31
What is dioecious?
Separate male and female individuals *Will NOT undergo sex change*
32
What is hermaphroditic?
Possess both male and female reproductive organs
33
What is simultaneous?
Both sexes at the same time
34
What is sequential?
First one sex then the other
35
What is protogynous?
Going from female to male
36
What is protandrous?
Going from male to female
37
What are the benefits of sex changes in fish
Increased fecundity and fitness
38
How is population growth affected?
By inputs and outputs (ex: birth rates, death rates, immigration, emmigration)
39
What is the tragedy of the commons?
Commons (a shared resource) will inevitably be degraded as individuals exploit the resources to maximize immediate individual benefit
40
What is the maximum sustainable yield?
The highest level of catch that can be maintained over time
41
What is the Magnuson-Stevens Act?
Primary law governing fisheries in federal waters: - Prevents overfishing - Rebuilds overfished stocks - Ensures safe and sustainable seafood - Establishes a country's EEZ
42
What are the national standards for the MSA?
1. Optimum yield: should operate at max yield 2. Scientific information: should be managed with scientific info. 3. Management units: stocks not populations 4. Allocations: no discrimination against residents of different states 5. Efficiency: environmentally better is not > efficiency 6. Variations and contingencies: account for math being wrong 7. Costs and benefits: minimize costs/unnecessary duplication 8. Communities: historical and cultural importance must be taken into account 9. Bycatch: should be minimized NOT eliminated 10: Safety of life at sea: decisions must be made to ensure fishermen's lives are not at danger
43
What is the annual catch limit framework?
Sets annual harvest limits for fisheries to prevent overfishing and ensure sustainability: - Annual target catch (ATC): you want to be here - Annual catch limit (ACL): you are allowed to go up to here BUT will trigger accountability measures - Acceptable biological catch (ABC): addresses scientific uncertainty and councils risk policy - Overfishing limit (OFL): maximum amount of catch without overfishing (MSY)
44
Describe stock overfishing vs. fleet overfishing
- Stock overfishing: the depletion of a specific fish stock - Fleet overfishing: the depletion of multiple stocks due to multiple fishing vessels
45
Describe a science-management framework
- Data collection - Stock assessment - Review and advise - Management decisions
46
Where can data come from and what are the issues with collecting data from these sources?
Fishery dependent sources: commercial and recreational fishers - Issue: are they lying, is the gear standardized, are fish developing avoidance Fishery independent sources: scientists and government agencies - Issues: high cost, small changes in gear make data unreliable
47
Describe the process of obtaining a stock assessment
Inputs: - Catch: total removals due to fishing overtime - Abundance: changes in stock overtime - Biology: life history info. Stock Assessment Model Outputs: - Stock status: overfishing or overfished? - Forecast
48
What is the difference between overfishing and overfished?
- Overfishing: the process of catching too many fish - Overfished: the result of overfishing (stock biomass is depleted) *For overfished, fishing mortality is the primary cause*
49
What are ways that stock status can be classified?
- Unknown: no accepted assessment to estimate stock status - Depleted: stock biomass falls below threshold - Overfished - Overfishing *For depleted, it is unclear whether fishing mortality is the primary cause*
50
What are some stock assessment types?
- Benchmark stock assessment: full analysis and review of stock (new info.) - Stock assessment update: update current stock status - Research stock assessment: develop or revise data - Operational stock assessment: determine/update current stock status - Stock monitoring updates: develop new catch advice *The last 3 are used by NOAA*
51
Describe fishing down a food web
- Large species (ex: sharks, whales, k-selected species) get depleted first BUT... they have lower MSY - Then you fish everything remaining (smaller fish) - Results in + feedback loop
52
What is aquaculture?
The cultivation of aquatic organisms in controlled aquatic environments for any commercial, recreational, or public purpose *Aquaculture is needed to keep up with the rising demand for seafood*
53
Describe intensive vs. extensive aquaculture
- Intensive: highly human managed - Extensive: not managed by humans relies on natural ecosystems
54
Describe monocultures vs. polycultures
- Monoculture: one type of organism - Polyculture: different types of organisms grown together
55
What are some problems with aquaculture?
- Introduction of chemicals: endocrine effects, affect biodiversity etc. - Nutrient loading: eutrophication, toxicity etc. - Biological interactions: interbreeding, competition, parasite and disease transfer etc.
56
What is wrong with aquaculture efficiency?
- 1/2 metric ton of wild caught fish is = to 1 ton of farmed fish

MAR 349 (6 decks)

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