Rate at which energy is stored in organic matter


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Rate at which energy is stored in organic matter

  • Rate at which energy is stored in organic matter

    • Photosynthesis using solar radiation
      • 99.9% of marine life relies directly or indirectly on photosynthesis for food
    • Chemosynthesis using chemical reactions


Chemical reaction that stores solar energy in organic molecules

  • Chemical reaction that stores solar energy in organic molecules



Gross primary production

  • Gross primary production

    • Total amount of organic carbon produced by photosynthesis per unit time in certain area
  • Net primary production

    • Gross primary production minus cellular respiration (growth, reproduction)
    • NPP = GPP – Respiration
  • New production

    • Nutrients added to local ecosystem (e.g., upwelling)
  • Regenerated production



Capture plankton

  • Capture plankton

    • Plankton nets
  • Ocean color

    • Chlorophyll colors seawater
    • SeaWiFs on satellite


Nutrients

  • Nutrients

    • Nitrate, phosphorous, iron, silica
    • Most from river runoff
    • Productivity high along continental margins
  • Solar radiation

    • Uppermost surface seawater and shallow seafloor
    • Euphotic zone surface to about 100 m (330 ft)




Visible light of the electromagnetic spectrum

  • Visible light of the electromagnetic spectrum

  • Blue wavelengths penetrate deepest

  • Longer wavelengths (red, orange) absorbed first



Color of ocean ranges from deep blue to yellow-green

  • Color of ocean ranges from deep blue to yellow-green

  • Factors

    • Water depth
    • Turbidity from runoff
    • Photosynthetic pigment (chlorophyll)
      • Eutrophic
      • Oligotrophic


SeaStar satellite/SeaWiFS view of ocean chlorophyll and land vegetation (productivity)

  • SeaStar satellite/SeaWiFS view of ocean chlorophyll and land vegetation (productivity)



Anthophyta

  • Anthophyta

    • Seed-bearing plants
  • Macroscopic (large) algae

  • Microscopic (small) algae

  • Photosynthetic bacteria



Only in shallow coastal waters

  • Only in shallow coastal waters

  • Primarily seagrasses &

  • Mangroves



Brown algae

  • Brown algae



Green algae

  • Green algae



Red algae

  • Red algae

    • Most abundant and most widespread of “seaweeds”
    • Varied colors


Produce food for 99% of marine animals

  • Produce food for 99% of marine animals

  • Most planktonic

  • Golden algae

    • Diatoms (tests of silica)
      • Most abundant single-celled algae – 5600+ spp.
      • Silicate skeletons – pillbox or rod-shaped  ooze
      • Some w/ sticky threads, spines  slows sinking


Coccolithophores (plates of ate)

    • Coccolithophores (plates of ate)
      • Flagellated
      • calcium carbon plates  possibly sunshades
      • Coccolithid ooze  fossilized in white cliffs of Dover


Dinoflagellates

  • Dinoflagellates

    • Mostly autotrophic; some heterotrophic or both
    • Flagella in grooves for locomotion
    • Many bioluminescent
    • Often toxic
      • Red tides (algal blooms)  fish kills (increase nutrients, runoff)




Dinoflagellates

  • Dinoflagellates

    • Pfiesteria in temperate coastal waters
    • Ciguatera (from) Gambierdiscus toxicus in tropical fishes
    • Paralytic, diarhetic, amnesic shellfish poisoning




Extremely small

  • Extremely small

  • May be responsible for half of total photosynthetic biomass in oceans



Varies from very low to very high depending on

  • Varies from very low to very high depending on

    • Distribution of nutrients
    • Seasonal changes in solar radiation
  • About 90% of surface biomass decomposed in surface ocean

  • About 10% sinks to deeper ocean

    • Only 1% organic matter not decomposed in deep ocean  reaches bottom
    • Biological pump (CO2 and nutrients to sea floor sediments)




Seasonal variation with temperature/light/nutrients

  • Seasonal variation with temperature/light/nutrients

    • Winter:
      • High winter winds  mixing of sediments/plankton
      • Low light & few phytoplankton  nutrients increase
    • Spring:
      • Phytoplankton blooms with more light, nutrients
      • Bloom continues until…
        • Nutrients run out
        • Herbivores eat enough phytoplankton
    • Summer: often low production due to lack of nutrients
    • Fall: Often 2O bloom, as winds bring up nutrients






Winter darkness

  • Winter darkness

  • Summer sunlight

  • Phytoplankton (diatoms) bloom

  • Zooplankton (mainly small crustaceans) productivity follows

  • Example

  • Arctic Ocean



Availability of sunlight and

  • Availability of sunlight and

  • High nutrients due to upwelling of North Atlantic Deep Water

    • No thermocline
    • No barrier to vertical mixing
  • Blue whales migrate to feed on maximum zooplankton productivity





Permanent thermocline is barrier to vertical mixing

  • Permanent thermocline is barrier to vertical mixing

  • Low rate primary productivity (lack of nutrients) above thermocline



High primary productivity in areas of…

  • High primary productivity in areas of…

    • Equatorial upwelling
    • Coastal upwelling
    • Coral reefs
      • Symbiotic algae
      • Recycle nutrients within the ecosystem






Ecosystem includes living organisms (biotic community) and environment (abiotic factors)

  • Ecosystem includes living organisms (biotic community) and environment (abiotic factors)

  • Solar energy converted to chemical energy by producers (mainly photosynthesis)



Consumers eat other organisms

  • Consumers eat other organisms

    • Herbivores
    • Carnivores
    • Omnivores
    • Bacteriovores
  • Decomposers breaking down dead organisms or waste products





Nutrients cycled from one chemical form to another

  • Nutrients cycled from one chemical form to another

  • Biogeochemical cycling

    • Example, nutrients fixed by producers
    • Passed onto consumers
    • Some nutrients released to seawater through decomposers
    • Nutrients can be recycled through upwelling




Suspension feeding or filter feeding

  • Suspension feeding or filter feeding

  • Deposit feeding

    • Take in detritus and sediment and extract usable organic matter
  • Carnivorous feeding

    • Organisms capture and eat other animals




Feeding stage is trophic level

  • Feeding stage is trophic level

  • Chemical energy is transferred from producers to consumers

  • On average, about 10% of energy is transferred to next trophic level





Primary producer

  • Primary producer

  • Herbivore

  • One or more carnivores







Both number of individuals and total biomass (weight) decrease at successive trophic levels

  • Both number of individuals and total biomass (weight) decrease at successive trophic levels

  • Organisms increase in size



Organisms associate in beneficial relationship

  • Organisms associate in beneficial relationship

    • Commensalism
      • One benefits without harm to other
    • Mutualism
    • Parasitism
      • One benefits and may harm the other




Taking more fish than is sustainable over long periods

  • Taking more fish than is sustainable over long periods

  • Remaining fish younger, smaller

  • About 30% of fish stocks depleted or overfished

  • About 47% fished at biological limit



Aquaculture becoming a more significant component of world fisheries

  • Aquaculture becoming a more significant component of world fisheries







Bycatch - Non-commercial species (or juveniles of commercial species) taken incidentally by commercial fishers

  • Bycatch - Non-commercial species (or juveniles of commercial species) taken incidentally by commercial fishers

  • Bycatch may be 25% or 800% of commercial fish

    • Birds, turtles, dolphins, sharks


Technology to help reduce bycatch

  • Technology to help reduce bycatch

    • Dolphin-safe tuna
    • TEDs – turtle exclusion devices
  • Driftnets or gill nets banned in 1989

    • Gill nets banned in Florida by constitutional amendment in 1994


Regulate fishing

  • Regulate fishing

    • Closings – Cod fisheries of New England
    • Seasons
    • Size limits
      • Minimum size limits –protects juveniles, less effective
      • Min/max size (slot) limits – preserves juvs and larger adults (contribute most reproductive effort)


Conflicting interests

  • Conflicting interests

    • Conservation vs. economic – “tragedy of the commons”
    • Self-sustaining marine ecosystems
    • Human employment
    • International waters
    • Enforcement difficult


Governments subsidize fishing

  • Governments subsidize fishing

    • Many large fishing vessels – often purchased with economic stimulus loans
    • 1995 world fishing fleet spent $124 billion to catch $70 billion worth of fish




Northwest Atlantic Fisheries such as Grand Banks and Georges Bank

  • Northwest Atlantic Fisheries such as Grand Banks and Georges Bank

  • Canada and U.S. restrict fishing and enforce bans

  • Some fish stocks in North Atlantic rebounding

  • Other fish stocks still in decline (e.g., cod)



Consumer choices in seafood

  • Consumer choices in seafood

  • Consume and purchase seafood from healthy, thriving fisheries

    • Examples, farmed seafood, Alaska salmon
  • Avoid overfished or depleted seafood

    • Examples, bluefin tuna, shark, shrimp, swordfish








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