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Job opportunity

Job opportunity. Falkowski lab seeks aquarist/ undergraduate assistant for the coral lab! If interested, contact Frank Natale: fnatale@marine.rutgers.edu. Review Competition for nutrients Light Critical and Compensation Depths Seasonal cycle and spatial variation

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Job opportunity

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  1. Job opportunity Falkowski lab seeks aquarist/ undergraduate assistant for the coral lab! If interested, contact Frank Natale: fnatale@marine.rutgers.edu

  2. Review • Competition for nutrients • Light • Critical and Compensation Depths • Seasonal cycle and spatial variation • Food web and microbial loop • Eutrophic vs. Oligotrophic food webs • Biological pump

  3. Competition for nutrients μmax1 = μmax2 Ks1<Ks2 Sp. 1 wins except at very high nutrients μmax2 > μmax1 Equal Ks Sp. 2 wins, but not by much at low nutrients μmax2 > μmax1 Ks1<Ks2 At low N, Sp. 1 wins At high N, Sp. 2 wins Species 1 Species 2 Specific Growth Rate μ Max growth rate (a constant) Half-saturation constant (a constant) Nutrient Concentration N

  4. Irradiance depth • Light attenuates with depth. • Longer wavelengths have greater absorption by particles and attenuate more with depth. • Too much light damages cells and reduces photosynthesis (photoinhibition).

  5. Compensation & Critical Depth

  6. Definitions • Autotrophs get their carbon and energy from inorganic sources. Phytoplankton are autotrophs because they get their carbon from CO2 and energy from light. • Heterotrophs get their carbon and energy from pre-formed organic matter. Zooplankton are heterotrophs because they get carbon and energy by eating phytoplankton.

  7. Some marine heterotrophs (Zooplankton) Copepods are the most numerous multicellular marine animals! Protists - single cells Size range: 1 to 1000 μm Life span: days to ~week Crustaceans Size range: 0.01 to 10 cm Life span: weeks to years Gelatinous animals Size range: mm to m Life span: months to ~year ciliates dinoflagellates krill copepods jellyfish salps

  8. Seasonal evolution of mixed layer

  9. Annual cycle in N. Atlantic Phytoplankton biomass Zooplankton biomass Spring bloom Fall mini- bloom Nutrients LightTemperature Mixing Mixing Stratified Relative increase

  10. Draw seasonal cycle of temperate and light profiles with critical depth here

  11. Primary production and its seasonal cycle vary greatly in space Chl a from SeaWIFS satellite

  12. Mixed layer is deeper in Atlantic than in Pacific Atlantic Ocean Depth (m) South pole Equator North Pole Pacific Ocean Depth (m) South pole Equator North Pole Temperature

  13. Nutrient limitation varies among oceans • Mixed layer is deeper in Atlantic than in Pacific • Remineralized nutrients accumulate in deep water, transported by ocean conveyer belt

  14. Atlantic vs. Pacific spring bloom Phytoplankton biomass Zooplankton biomass Winter: Deep mixed layer, Production shuts down Spring: Phytoplankton bloom Zooplankton - slow to catch up Winter: Shallower mixed layer, Continuous low production Spring: Phytoplankton bloom Zooplankton - right there to eat the bloom!

  15. Spring in the Arctic is darker & colder than winter at mid-latitudes [Also Irradiance] 90oN = N. Pole 60oN ~Anchorage,AK 30oN ~N. Florida 0oN = Equator

  16. Seasonal cycle varies with latitude Nutrients Light [Nutrient] Latitude Light Winter Spring Summer Autumn Winter Lalli & Parsons

  17. Annual cycles in other regions Phytoplankton biomass Zooplankton biomass Try this on your own: Draw the vertical profiles of temperature and light and the critical depth for each region as we did in class for the North Atlantic.

  18. Biological Pump Photosynthesis respiration Chisholm, 2000

  19. What’s in a liter of seawater? 1 Liter of seawater contains: • 1-10 trillion viruses • 1-10 billion bacteria • ~0.5-1 million phytoplankton • ~1,000 zooplankton • ~1-10 small fish or jellyfish • Maybe some shark, sea lion, otter, or whale poop This basking shark can filter 25 million L seawater per day! *The bigger you are, the fewer you are

  20. Assume a trophic transfer efficiency of 10% Biomass 10 100 1000 Efficiency 0.1 0.1 fish zooplankton phytoplankton Trophic transfer efficiency = fraction of biomass consumed that is converted into new biomass of the consumer

  21. Traditional view of simple food web:Small things are eaten by (~10x) bigger things Heterotrophs Autotrophs Size (μm)

  22. Have to add heterotrophic bacteria, heterotrophic protists, autotrophic microbes Heterotrophs Autotrophs Size (μm)

  23. Bacteria absorb organic molecules leaked by microbes and phytoplankton. This creates a microbial “loop.” Heterotrophs Autotrophs Size (μm) Dissolved organic matter

  24. Zoom in on Biological Pump Photosynthesis respiration Chisholm, 2000

  25. Phytoplankton are eaten by zooplankton

  26. Plankton size structure is important Diatoms, dinoflagellates Coccolithophores, cyanobacteria

  27. Importance of microbial loop depends on environmental conditions. Microbial loop

  28. Definitions • Eutrophic environments have high nutrient concentrations and high productivity. Coastal upwelling regions and estuaries are Eutrophic. • Oligotrophic environments have low nutrients and low productivity. Subtropical gyres (open ocean) are Oligotrophic. • It takes a lot of mixing or a big nutrient influx to make an environment eutrophic. Stratified systems eventually must become oligotrophic.

  29. Eutrophic -coastal -estuaries -upwelling Oligotrophic -open ocean -central gyres Transparent L. Tahoe Diatom bloom in Barents Sea

  30. In eutrophic systems, large phytoplankton (diatoms) dominate and more biomass goes directly to large plankton and fish. Temp. Depth Dcr Microbial loop is less important

  31. Temp. Depth In oligotrophic systems, small phytoplankton (e.g. cyanobacteria) dominate and biomass goes through more levels of plankton to get to fish. Dcr Microbial loop is key

  32. Oligotrophic Eutrophic Open Ocean Tuna Carniv. Fish Carniv. Plankton Herbiv. Plankton Phytoplankton 5 Levels 10% Efficiency Coastal Ocean Carniv. Fish Carniv. Plankton Herbiv. Plankton Phytoplankton 4 Levels 15% Efficiency Upwelling Zone Anchovies Phytoplankton 2 Levels 20% Efficiency

  33. =109 metric tons C per year =109 metric tons fish per year Open ocean Coastal ocean Upwelling zones 5 Trophic levels 10% Efficiency 4 Trophic levels 15% Efficiency 2 Trophic levels 20% Efficiency

  34. How does food-web structure affect the export of carbon to deep ocean?

  35. How does organic matter get to the bottom of the ocean ? • Dead cells and fecal pellets (plankton poop) sink. Big ones sink faster. • Dissolved organic matter, pieces of gelatinous animals etc. stick together and form bigger “marine snow” that sinks. Organic debris is collectively known as Detritus.

  36. Bigger plankton sink faster. They also have bigger, faster-sinking fecal pellets. Large plankton and their fecal pellets Marine snow Small plankton and their fecal pellets

  37. In eutrophic conditions, there are more, larger particles that sink into deep ocean. Temp. Depth Dcr Large fecal pellets Large Marine snow

  38. Temp. Depth In oligotrophic conditions, there are fewer, smaller particles that sink more slowly into deep ocean. Dcr small fecal pellets

  39. Eutrophic vs. Oligotrophic summary

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