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🌿 topic 4 ESS > 4.3 aquatic food production systems > Flashcards

4.3 aquatic food production systems Flashcards

1
Q

marine ecosystems

A
  • oceans
  • estuaries
  • mangroves
  • coral reefs
  • salt-marshes
  • 70% of earths surface
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2
Q

marine trophic levels
primary producers

A
  • base of the food web
  • microscopic phytoplankton, seaweed
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3
Q

marine trophic levels
primary consumers

A
  • zooplankton
  • small floating animals that graze on phytoplankton
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4
Q

marine trophic levels
secondary consumers

A
  • small predators, some fish
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5
Q

marine trophic levels
tertiary consumers

A
  • top predators, large fish
  • marine mammals
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6
Q

coastal waters and shallow seas tend to be more productive because

A
  • nutrients that precipitate out a resuspended by wind and currents in shallow water
  • river input brings in more nutrients
  • sunlight can penetrate down to the sea floor, driving photosynthesis
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7
Q

freshwater trophic levels
primary producers

A
  • phytoplankton
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8
Q

freshwater trophic levels
primary consumers

A
  • zooplankton
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9
Q

freshwater trophic levels
secondary consumers

A
  • fish
  • birds
  • ducks
  • drogs
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10
Q

freshwater trophic levels
tertiary consumers

A
  • large fish and birds
  • mammals
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11
Q

factors contributing to the increasing demand for fish

A
  • human population growth
  • promotion of health benefits consuming fish, protein, nutrients, essential fatty acids
  • better standards of living
  • imports
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12
Q

seal hunting

A
  • traditional cultures, only 3% of total seals hunted globally each year

controversial
- concerns over species becoming threatened
- inhumane methods of killing
- most meat wasted
- incorrectly blamed for the collapse of newfoundland cod
- ice melting threatening seals habitat

government
- quotas
- open and close hunting season
- limited boats and catches per day
- banning babies and certain species
- not enforces well

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13
Q

energy efficiency of aquatic food systems

A
  • less efficient than terrestrial food systems
  • less light, absorbed or reflected by water
  • humans eat high up the food chain, greater energy loss
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14
Q

growth in capture fisheries

A
  • population, popularity
  • more fishing fleets
  • able to fish further from the shore and stay out longer
  • sonar, radar, satelite technology
  • process, preserve and freeze out at sea
  • changing fishing gear
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15
Q

use of nets
trawler nets

A
  • dragging funnel shaped net across the seabed
  • damages seabed
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16
Q

use of nets
drift nets

A
  • hung vertically in water
  • bycatch, turtles, sharks, dolphins
  • banned in many places
17
Q

marine capture fisheries not continuing to expand?

A
  • consequence of overfishing and habitat degradation
18
Q

maximum sustainable yield (MSY)

A
  • max harvest that can be obtained annually without impacting the standing stock and it’s ability to replenish itself
  • hard to calculate, can still lead to over-exploitation
19
Q

reasons for overfishing
property rights

A
  • nobody owns the fish, swim through large areas across national boundaries
  • don’t want to spend money conserving for other countries to harvest
20
Q

reasons for overfishing
zero sum game

A
  • need to convince people to sacrifice short term gain to benefit the future
  • fish less, others fish more, conservation loose out
21
Q

managing fish stocks
use of quotas

A
  • estimate MSY, politicians set total allowable catches (TACs)
  • bycatch discarded as waste, penalties
22
Q

managing fish stocks
reduction in fishing effort

A
  • reducing number of boats, boat size, fishing gear used, limits on minimum fish size, fishing times
23
Q

managing fish stocks
use of exclusion zones and marine protected areas

A
  • fishing banned in certain areas
  • legislation enforced
24
Q

newfoundland cod fishing case study

A
  • tragedy of commons
  • largest cod stocks
  • 1950s technology development
  • 1990s, loss of fish stocks, still low numbers 30 years later
  • unemployment
25
Q

iceland cod case study

A
  • slight decline, government took action to prevent similar to newfoundland
  • protecting territorial waters
  • restrictions on fishing gear and fleet sizes
  • strict quotas
  • banning disposal of bycatch
  • diversification of target species
  • use of exclusion zones
  • high level of enforcement
26
Q

aquaculture
open based system

A
  • most popular
  • farming within a natural aquatic ecosystem, sea, lake
  • little control over environmental factors
27
Q

aquaculture
semi closed system

A
  • abstraction of water from sea or lakes to use within tanks or ponds on land
  • greater control over environmental conditions
  • more expensive
28
Q

environmental impacts of aquaculture
increase in organic sediments

A
  • waste, uneaten fish food, feces, medicines
  • precipitates to below the cage and can accumulate
  • can cause anoxic conditions, reducing biodiversity
  • movement, sufficient aeration of water
29
Q

environmental impacts of aquaculture
increase in available nutrients

A
  • soluble nutrients released from uneaten fish food and feces, increase dissolved nutrient levels in the water
  • increase primary production, algal bloom, harm fish
30
Q

environmental impacts of aquaculture
use of medicines and hormones

A
  • contaminate the water and impact other aquatic life
31
Q

environmental impacts of aquaculture
use of antifouling agents

A
  • used to prevent growth of algae and other organisms on the cage
  • toxic to mollusks, decrease biodiversity
32
Q

environmental impacts of aquaculture
spread of disease

A
  • heavily stocked, disease spreads from one fish to another
  • potentially outside of cages
33
Q

environmental impacts of aquaculture
escaped fish

A
  • threaten wild stocks, competing, transmit disease
  • may have advantage for survival over wildfish, decrease biodiversity
34
Q

environmental impacts of aquaculture
attracted predators

A
  • predators can become caught in the net

-underwater acoustics to deter predators

35
Q

managing environmental impacts of aquaculture

A
  • reducing waste of uneaten food, not overfeeding
  • effective application of medicine
  • regular removal of dead fish
  • moving the cages to prevent build up of organic sediments
  • sufficient movement and water exchange, disperse blooms, waste/nutrient build up
  • aerate the water
36
Q

environmental impacts of aquaculture
loss of habitats

A
  • clear land for aquaculture
  • mangrove forests, reduce natural storm protection
  • space taken up other animals can’t use
37
Q

thailand shrimp aquaculture case study

A
  • 2/3 mangrove forests destroyed
  • all problems with aquaculture happening
  • international pressure to reduce environmental degradation
  • legislation, better controls

🌿 topic 4 ESS (4 decks)

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