lecture #15 week #13 - fullcoll.edu
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Lecture #15 Week #13
A.K. Morris, Ph.D.
Chapter 13
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Primary productivityWhat is it?Who does it?What’s it good for?
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Trees….SunlightLeaves
Large organic structuresConstant energy sourceMillions of solar panels
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Sun provides ENERGY for lifeAll organisms need ENERGY & are composed of CARBONDifferent ways of getting ENERGY & CARBON
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Carbon and Energy SourcesPhotoautotrophs do “photosynthesis”Energy source = sunlightCarbon source = CO2(or a derivative)
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Contrast with “Heterotrophs”Consumers: get E & C from other organismsC source = autotrophs/ each otherE source = autotrophs/ each other
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Lecture #15 Week #13
A.K. Morris, Ph.D.
Who is a photoautotroph? Plants and macroalgaeMany protists (unicellular algae)Some bacteria
Eelgrass
Giant kelp (brown alga)
Coccolithophorids
Ciliate
Cyanobacteria
Cyanobacteria 7
361 million square kilometersLots of area for microscopic solar panelsPhytoplankton (photoautotrophic plankton)
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© J. Molemaker 2005, UCLA
PhytoplanktonMicroscopic algal and bacterial cellsPlankton size classification:Microplankton – diatoms & dinoflagellates(20‐200 μm) “big”
Nanoplankton – diatoms & coccolithophorids(2‐20 μm) “small”
Picoplankton – cyanobacteria(0.2‐2 μm) “tiny”
Gonyaulax sp.
Noctiluca sp.
20 µm
Thalassiosira sp.Emiliana huxleyiProchlorococcus sp. 9
History of Plankton StudiesA story of politics, treachery, and occupational backstabbing!
Your book cites Victor Hensen asthe “father of modern biologicaloceanography”History is always written by thewinners
Victor Hensen (1835-1924) 10
Ernst HaeckelOne of the top natural scientists… ever!Coined the term “Ecology”Huge Darwin supporterStarted studying marine life in 1856(15 years before Hensen)“Kunstformen der Natur”, 1899‐1904(Art Forms of Nature)A multi‐volume epic work.
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Lecture #15 Week #13
A.K. Morris, Ph.D.
The Kiel Commission
North Seas Fisheries unpredictableHired Victor Hensen as theirchief researcherProfessor of Physiology – studied human food energetics5 research cruises from 1871–1891
Victor Hensen (1835-1924)
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Victor HensenHensen determined the ocean was homogeneous with low abundance.Patches would be “discarded” as contaminatedPoor, rudimentary statistics
1893 – Haeckel wrote a scathing review of Hensen’s work
“Dumkoff! Ihregesamte arbeit sehr
schrecklich!”
Hmm…
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Haeckel, E., 1893, U.S. Comm. Fish. And Fisheries.Raskoff, K.A. et al., 2003, Biol. Bull. 204: 68-80.
Hensen Haeckel
15Harris, R.P., et al., 2000, ICES Zooplankton Methodology Manual, Academic Press, San Diego, CA.
Hensen
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Pre‐1920sPlankton under‐represented in food webs.Primary productivity under‐reported
1927 – new experimental design – Light‐and‐dark bottle method
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Primary Production Studies Mature
1920’s – Connection between PP and light availability1930’s – Phyto conc. estimated indirectly by correlation with elementsRedfield Ratio – C106:N16:P1
Alfred Redfield 18
Lecture #15 Week #13
A.K. Morris, Ph.D.
Recall Limiting NutrientsThe item that limits growth or reproductionNOT necessarily the item in least supply(car analogy: gas and oil)
Distribution of nutrients oftendetermines distr. of organisms
This means PP estimated byconc. of essential nutrients
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14C to estimate PP
Method used by the intrepid oceanographer Sean Chamberlin –did his Ph.D. work waaaaay back in the 1980’s
Fluorescence intensity is proportional to chlorophyll conc.
Fig. 13.420
MODIS SatellitesMODerate Resolution Imaging SpectroradiometerPhytoplankton mostly have Chlorophyll aChl a fluoresces at a known frequency
Terra (EOS AM‐1) launched by NASA 12/18/99
Aqua (EOS PM‐1) launched 5/4/02
VIDEO
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Photosynthetically Available Radiation
Phytoplankton biomass from MODIS sensor
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Phytoplankton biomass from MODIS sensor
Chlorophyll a
24So what does this mean? Why is productivity different from light availability???
Lecture #15 Week #13
A.K. Morris, Ph.D.
CTDsTypically equipped with fluorometers today
Fluorometerby Wetlabs®
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Fig. 13.7
Fine‐scaledetermination
Virtually all photosynthesizersuse Chl a
Absorbs light that penetrates deepestChl b common in cyanobacteriaChl c common in diatoms and coccolithophoridsDinoflagellates have other accessory pigments
Further IDs require high‐pressureliquid chromatography
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How does photosynthesis work?
2 Steps:1. Light‐dependent rxns:
Convert light E to chem E (ATP)
2. Light‐independent rxns: Use ATP to build sugar
It’s waaay morecomplex than this…
27Sugars!
Photosynthesis‐“lite” (simplified)Photosynthesis
E‐storing pathway Requires CO2 & H2OReleases O2
Aerobic RespirationE‐releasing pathwayRequires O2
Releases CO2 & H2O
CO2 + H2O + light (CH2O) + H2O + O2(Sugar)
Photosynthesis –
CO2 + H2O + energy (CH2O) + H2O + O2Respiration –
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But note the following…
Photosynthesizers need energy… even when it’s dark.When it’s dark, phytoplankton do respiration!
Summer = more daylight in N. Hemisphere, so greater net PPWinter = less daylight in N.H., so less net PP
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Nutrient Cycling
Replenishing raw materials“Sloppy feeding” and fecal pellets by zooplankton
Fecal pellets sink faster.Vertical migration redistributes C deeper
Euphausiid (krill)
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Lecture #15 Week #13
A.K. Morris, Ph.D.
Vertical migration:Where is most of the food?Where can predators best see?Largest migration on the planet happens every day
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(cont…)Vertical migration: during day, live at depth (200m) and at night swim to surface to feedAdvantage:
Avoid predationSlow metabolism / save E. in cooler water
Disadvantage:Cannot feedMigrating uses E.Slow metabolism / cannot develop
Positive Outcome:Transports carbon deep
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Vertical MigratorsZooplankton:
Herbivores (and some carnivores)One of the most numerous organisms on Earth
Copepod
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Vertical Distribution Challenges
Compensation depth vs. Critical depth
Fig. 13.13
Photosynthesis Respiration
(Gain)
(Loss)
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Vertical Distribution Challenges
Compensation depth vs. Critical depth
Fig. 13.13
Photosynthesis Respiration
(Gain)
(Loss)
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Vertical Distribution Challenges
Compensation depth vs. Critical depth
Fig. 13.13
Photosynthesis Respiration
(Gain)
(Loss)
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Lecture #15 Week #13
A.K. Morris, Ph.D.
Seasonal Primary Productivity
Limits: light, nutrients.These things vary seasonally
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Seasonal Primary ProductivityWinter: best nutrientsSummer: best lightSpring: best compromise!
Baltic Sea late spring phytoplankton bloomAqua/MODIS true-color image, June 7, 200538
CaliforniaUpwellingSeasonal upwellingbrings nutrient richbottom waters into the photic zone.Leaves a temperature signatureChlorophyll conc. images mirror temp.
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SurfaceChlorophyll a
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Notice the DistributionTemperate zonesUpwelling zones
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