The Oceanic Carbon Cycle: Biological Pump

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The Oceanic Carbon CycleBiological Pump

• Primary producers who are they?
• How does the pump work transport to the bottom
• Open ocean ecosystems

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high diversityDEEP SEA
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Deep-Sea diverse life forms

• Deep-sea thought to be without life (azoic)
  until 19th century deep-sea exploration
  expeditions
• Erebus and Terror, 1839-1843, James Ross
  Clark
• Lightning and Porcupine, 1868-1869, Wyville
  Thompson
• Challenger, 1872-1876, Wyville Thompson, J. W.
  Murray (ForaminiferaH .B. Brady, 1884)

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SURFACE OCEAN PRIMARY PRODUCTIVITY
Satellite data (CZCS, SeaWIFS)
High productivity input of nutrients (N, P) from
land Seasonality
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Oceanic spring bloom (high-mid latitudes)

• Winter light limitation (insolation, storms mix
  phytoplankton below photic zone)
• Nutrients not (fully) used accumulate
• Spring more light, warming causes
  stratification, keeps plankton within photic zone
• Bloom (until nutrients used up, zooplankton eats
  phytoplankton)

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EUKARYOTES(multicellular)FungiAnimaliaPlantae
PROTISTS EUKARYOTES (unicellular)
LIFE ON EARTH
PROKARYOTES

• Molecular phylogenies
• Protein sequences
• Small subunit RNA

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Oceanic primary producers

• Prokaryotes (unicellular, simple cell, asexual
  reproduction 0.6 mm) - cyanobacteria
  Prochlorococcus, Synechococcus) up to 2/3 of
  primary productivity in the oceans
• Eukaryotes (complex cell - nucleus - sexual and
  asexual reproduction tens of mm)
• Bacillariophyceae - Opaline Silica skeleton
  Diatoms
• Haptophyceaea
• Calcium-carbonate skeleton Calcareous
  Nannoplankton
• No skeleton Phaeocystis
• Dinophyceae - organic -walled cysts
  Dinoflagellates

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CALCAREOUS NANNOPLANKTON
COCCOLITHOPHORES

• Polysaccharide gels (transparent exopolymer
  particles)

(Haptophyte Algae) Diameter 20-30 mm
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Planktonic foraminifer
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Prymnesiophytes (Haptophytes) -Phaeocystis

• Polysaccharide gels (transparent exopolymer
  particles)

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Transparent Exopolymer Particles

• Phaeocystis blooms at high latitudes (survive in
  sea ice)
• 10 of annual global marine primary productivity
• Much of this in form of gels - major part of
  dissolved organic carbon in oceans
• Secrete dimethylsulfide - add sulfur to atmosphere

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Diatoms

• Today up to 20-40 net primary production, 50
  organic carbon exported

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Diatoms

• Rapid delivery of diatoms to sea floor in frontal
  zones (Kemp et al., 2006)
• giant diatoms in mats e.g., Fragilariopsis,
  Thalassiothrix, Rhizosolenia

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Dinoflagellates

• Dinophyceae

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Dinoflagellates harmful algal blooms (HABs)
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Type of primary producers/productivity of oceans

• Open ocean, low productivity (central gyres)
  prokaryotes, some dinoflagellates
• Open ocean, higher productivity calcareous
  nannoplankton
• Open ocean, highest productivity diatoms,
  Phaeocystis
• Coastal ocean, high productivity
  dinoflagellates, Phaeocystis

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Oceanic primary productivity different dominant
producers - fertility
ANNUAL
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Deep-sea environment cold, dark,high pressure,
very little food.
Food supplied by surface productivity, miles up
biological pump
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How much food reaches the bottom?Not very much
(lt1 to few of PP)

• e.g., Martin et al., 1987 north-east Pacific
  stations
• F1.53(z/100)-0.858
• zdepth

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Oceanic food chain
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Food from surface to bottombiological pumphow
does it work?

• Marine snow (4 mm particle, dead and dying
  phytoplankton, zooplankton exoskeletons, fecal
  matter)
• 102-103 m/day

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Organic matter from surface to bottombiological
pump

• Ballasted by
• silica (diatoms)
• carbonate (foraminifera, nannoplankton)
• terrigenous dust
• In fecal pellets
• Stuck together by polysaccharides (Phaeocystis,
  diatoms, cyanobacteria, calcareous nannoplankton)
• In giant balls of mucus - larvacean houses
• Carrion falls (dead whales)
• Lateral transport (refractory organic matter)
• Discrepancy between food requirements of faunas
  and supply in sediment traps faunas need more
  than what is delivered

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Larvacean houses (tunicates)2-3 feet diameter

• Tunicates are Chordates (related to us
  vertebrates - lancelet fish)

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• We do not understand transport of organic matter
  to the sea floor in the present ocean, nor
  importance of prokaryotic productivity
• We can not predict the effects of global warming
  and increased nutrients on carbon cycle in the
  oceans

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Oceanic primary productivity - how limited?
Transport to sea floor - how limited? Can we
manipulate (carbon sequestration)?
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In some regions N and P are NOT limiting

• "high-nutrient, low-chlorophyll (HNLC) regions,
  e.g. equatorial Pacific
• Not enough iron (Fe)

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