Ecology B.Species Interactions 1.Intraspecific competition Ex – Competition for algae by sea...
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![Page 1: Ecology B.Species Interactions 1.Intraspecific competition Ex – Competition for algae by sea urchins Ex – Competition for shells by hermit crabs 2.Interspecies.](https://reader036.fdocuments.us/reader036/viewer/2022062421/56649d975503460f94a80dfe/html5/thumbnails/1.jpg)
EcologyB. Species Interactions
1. Intraspecific competition• Ex – Competition for algae by sea urchins
• Ex – Competition for shells by hermit crabs
2. Interspecies competition
![Page 2: Ecology B.Species Interactions 1.Intraspecific competition Ex – Competition for algae by sea urchins Ex – Competition for shells by hermit crabs 2.Interspecies.](https://reader036.fdocuments.us/reader036/viewer/2022062421/56649d975503460f94a80dfe/html5/thumbnails/2.jpg)
EcologyB. Species Interactions
2. Interspecific competition – Competitive exclusion
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EcologyB. Species Interactions
3. Predation• Natural selection favors increased predation efficiency• Predators can control prey populations (Top-down)
• Reduce competition/competitive exclusion• Prey can control predator populations (Bottom-up)
• Prey = food• Some prey have evolved defense mechanisms
• Ex – Spines in plankton• Ex – Poisonous chemicals in algae and mollusks
• Some defenses are inducible• Ex – Barnacles grow upright when predatory snails absent and horizontally when snails present• Ex – Algae produce more bad-tasting chemicals after being damaged
• Coevolution – Evolutionary “arms race”
![Page 4: Ecology B.Species Interactions 1.Intraspecific competition Ex – Competition for algae by sea urchins Ex – Competition for shells by hermit crabs 2.Interspecies.](https://reader036.fdocuments.us/reader036/viewer/2022062421/56649d975503460f94a80dfe/html5/thumbnails/4.jpg)
EcologyB. Species Interactions
3. Predation• Natural selection favors increased predation efficiency
• Predators can control prey populations (Top-down)
• Reduce competition/competitive exclusion
• Prey can control predator populations (Bottom-up)
• Prey = food
![Page 5: Ecology B.Species Interactions 1.Intraspecific competition Ex – Competition for algae by sea urchins Ex – Competition for shells by hermit crabs 2.Interspecies.](https://reader036.fdocuments.us/reader036/viewer/2022062421/56649d975503460f94a80dfe/html5/thumbnails/5.jpg)
EcologyB. Species Interactions
3. Predation• Some prey have evolved defense mechanisms
• Ex – Spines in plankton
• Ex – Poisonous chemicals in algae and mollusks
• Some defenses are inducible
• Ex – Barnacles grow upright when predatory snails absent and horizontally when snails present
• Ex – Algae produce more bad-tasting chemicals after being damaged
• Coevolution – Evolutionary “arms race”
![Page 6: Ecology B.Species Interactions 1.Intraspecific competition Ex – Competition for algae by sea urchins Ex – Competition for shells by hermit crabs 2.Interspecies.](https://reader036.fdocuments.us/reader036/viewer/2022062421/56649d975503460f94a80dfe/html5/thumbnails/6.jpg)
EcologyB. Species Interactions
4. Symbiosis• Relationship between host and symbiont
a. Commensalism• One partner benefits, other unaffected• Ex – Barnacles living on whale
b. Parasitism• One partner benefits at expense of other• Common in marine environment• Ex – Tapeworm in whale
c. Mutualism• Both partners benefit• Ex – Cleaner wrasses and shrimps on coral reefs• Ex – Anemonefishes and anemones
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EcologyC. Trophic Structures
• Energy and matter flow through ecosystems can be described through trophic relationships
• Relationships between producers and consumers = food chain
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EcologyC. Trophic Structures
• Food chains are often simplistic – alternative is a food web
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EcologyC. Trophic Structures
• Food chains are often simplistic – alternative is a food web
![Page 10: Ecology B.Species Interactions 1.Intraspecific competition Ex – Competition for algae by sea urchins Ex – Competition for shells by hermit crabs 2.Interspecies.](https://reader036.fdocuments.us/reader036/viewer/2022062421/56649d975503460f94a80dfe/html5/thumbnails/10.jpg)
EcologyC. Trophic Structures
• Energy transfer between trophic levels not 100% efficient• Matter consumed by metabolism
• Energy released as heat
• Matter released as waste
• Transfer efficiency ~ 10% (5-20%)
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EcologyC. Trophic Structures
• Energy transfer can be illustrated as pyramid of energy• Higher levels contain progressively less energy
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EcologyC. Trophic Structures
• Energy transfer can be illustrated as pyramid of energy• Higher levels contain progressively less energy
![Page 13: Ecology B.Species Interactions 1.Intraspecific competition Ex – Competition for algae by sea urchins Ex – Competition for shells by hermit crabs 2.Interspecies.](https://reader036.fdocuments.us/reader036/viewer/2022062421/56649d975503460f94a80dfe/html5/thumbnails/13.jpg)
EcologyC. Trophic Structures
• Decomposers – break down waste products
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Marine ResourcesA. Fisheries
• Seafood is ~1% of all food eaten worldwide
• Seafood especially important in poor coastal nations with low protein availability
• World seafood catch stabilized by late 1980s
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Marine ResourcesA. Fisheries
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Marine ResourcesA. Fisheries
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Marine ResourcesA. Fisheries
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Marine ResourcesA. Fisheries
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Marine ResourcesA. Fisheries
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Marine ResourcesA. Fisheries
1. Clupeoid fishes• Herrings, sardines, anchovies, menhadens, shads• Feed on plankton (use gill rakers)• Form large schools over continental shelves and in upwelling zones
• Caught with purse seines• Industrial fisheries
- Fish meal (protein supplement in animal feed)
- Fish oil (margarine, cosmetics, paint)
- Fish flour (protein supplement for humans)
- Fertilizers
- Pet food
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Marine ResourcesA. Fisheries
1. Clupeoid fishes
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Marine ResourcesA. Fisheries
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Marine ResourcesA. Fisheries
2. Cods and related fishes• Cods, pollock, haddock, hakes, whiting
• Demersal and benthopelagic cold-water fishes
• Caught with bottom trawls
• Grand Banks (Newfoundland), Georges Bank (New England) and North Sea supported extensive cod fisheries until 1992, 1994, and 2001, respectively
• Cod populations crashed; catches plummeted
• Ex – North Sea catch
• 1971 – 277,000 tonnes
• 2001 – 59,000 tonnes
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Marine ResourcesA. Fisheries
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Marine ResourcesA. Fisheries
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Marine ResourcesA. Fisheries
3. Tunas• Skipjack, yellowfin, albacore, bigeye, bluefin
• Primarily eaten in affluent countries
• Can be very expensive (up to $40,000 for a choice bluefin in Tokyo)
• Highly migratory species
• Caught with purse seines, longlines, gill nets, rod and reel
• Often associate with floating objects, dolphin schools
• Juveniles caught in purse seines may be finished in net pens (aquaculture)
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Marine ResourcesA. Fisheries
3. Tunas
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Marine ResourcesA. Fisheries
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Marine ResourcesA. Fisheries
4. Other species• Flatfishes, rockfishes, mackerels, salmon
• Mostly coastal
• Threatened by coastal pollution, damming of rivers (salmon), overfishing
• Flatfishes and rockfishes harvested extensively in US
• Salmon farmed heavily in Canada, Chile
• Non-finfish
• Squid, octopus
• Clams, oysters, scallops
• Crabs, lobsters
• Sea urchin, sea cucumber
• Barnacles, jellyfish
• Sea turtles, seals, whales
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Marine ResourcesA. Fisheries
5. Fishery Yields
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Marine ResourcesA. Fisheries
5. Fishery Yields
• Overfishing leads to1) Stock depletion
2) Reduced catch rate
3) Capture of smaller individuals
4) Unsustainable harvest
• Biological – Can’t reproduce fast enough
• Economic – Can’t catch enough to make a profit
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Marine ResourcesA. Fisheries
5. Fishery Yields