Primary productivity Carbon and Energy Sources

Lecture #15
Week #13
Primary productivity
y What is it?
y Who does it?
Chapter 13
y What’s it good for?
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y Sun provides ENERGY for life
y All organisms need ENERGY & are composed of CARBON
y Different ways of getting ENERGY & CARBON
y Trees….
y Large organic structures
y Sunlight
y Leaves
y Constant energy source
y Millions of solar panels
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Contrast with “Heterotrophs”
Carbon and Energy Sources
y Consumers: get E & C from other organisms
y Photoautotrophs do “photosynthesis”
y Energy source = sunlight
y C source = autotrophs/ each other
y E source = autotrophs/ each other
y Carbon source = CO2
(or a derivative)
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A.K. Morris, Ph.D.
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Lecture #15
Week #13
© J. Molemaker 2005, UCLA
Who is a photoautotroph? y Plants and macroalgae
y Many protists (unicellular algae)
y Some bacteria
Coccolithophorids
Cyanobacteria
Eelgrass
y 361 million square kilometers
y Lots of area for microscopic solar panels
y Phytoplankton (photoautotrophic plankton)
Ciliate
Cyanobacteria
Giant kelp (brown alga)
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20 µm
Phytoplankton
History of Plankton Studies
y Microscopic algal and bacterial cells
y Plankton size classification:
y A story of politics, treachery, and occupational backstabbing!
Gonyaulax sp.
y Microplankton – diatoms & dinoflagellates
(20‐200 μm) “big”
y Your book cites Victor Hensen as
the “father of modern biological
oceanography”
y Nanoplankton – diatoms & coccolithophorids
(2‐20 μm) “small”
Noctiluca sp.
y Picoplankton – cyanobacteria
(0.2‐2 μm) “tiny”
Prochlorococcus sp.
y History is always written by the
winners
Emiliana huxleyi
Thalassiosira sp.
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Victor Hensen (1835-1924)
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Ernst Haeckel
y One of the top natural scientists… ever!
y Coined the term “Ecology”
y Huge Darwin supporter
y Started studying marine life in 1856
(15 years before Hensen)
y “Kunstformen der Natur”, 1899‐1904
(Art Forms of Nature)
A multi‐volume epic work.
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A.K. Morris, Ph.D.
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Lecture #15
Week #13
Victor Hensen
The Kiel Commission
y Hensen determined the ocean was homogeneous with low abundance.
y North Seas Fisheries unpredictable
y Hired Victor Hensen as their
chief researcher
Hmm…
Victor Hensen (1835-1924)
y Professor of Physiology – studied human food energetics
y Patches would be “discarded” as contaminated
y Poor, rudimentary statistics
“Dumkoff! Ihre
gesamte arbeit sehr
schrecklich!”
y 5 research cruises from 1871–1891
y 1893 – Haeckel wrote a scathing review of Hensen’s work
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Hensen
Haeckel, E., 1893, U.S. Comm. Fish. And Fisheries.
Raskoff, K.A. et al., 2003, Biol. Bull. 204: 68-80.
Haeckel
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Hensen
Harris, R.P., et al., 2000, ICES Zooplankton Methodology Manual, Academic Press, San Diego, CA.
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Pre‐1920s
Primary Production Studies Mature
y Plankton under‐represented in food webs.
y 1920’s – Connection between PP and light availability
y 1930’s – Phyto conc. estimated indirectly by correlation with elements
y Primary productivity under‐
reported
y Redfield Ratio – C106:N16:P1
y 1927 – new experimental design – Light‐and‐dark bottle method
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A.K. Morris, Ph.D.
Alfred Redfield
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Lecture #15
Week #13
Recall Limiting Nutrients
14C to estimate PP
y The item that limits growth or reproduction
y Method used by the intrepid oceanographer Sean Chamberlin –
did his Ph.D. work waaaaay back in the 1980’s
y NOT necessarily the item in least supply
(car analogy: gas and oil)
y Distribution of nutrients often
determines distr. of organisms
y This means PP estimated by
conc. of essential nutrients
y Fluorescence intensity is proportional to chlorophyll conc.
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Fig. 13.4
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MODIS Satellites
y MODerate Resolution Imaging Spectroradiometer
y Phytoplankton mostly have Chlorophyll a
y Chl a fluoresces at a known frequency
Terra (EOS AM‐1) launched by NASA 12/18/99
VIDEO
Aqua (EOS PM‐1) launched 5/4/02
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Phytoplankton biomass from MODIS sensor
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Phytoplankton biomass from MODIS sensor
Photosynthetically Available Radiation
Chlorophyll a
So what does this mean? Why is productivity different from light availability???
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A.K. Morris, Ph.D.
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Lecture #15
Week #13
Fig. 13.7
Fine‐scale
determination
CTDs
y Typically equipped with fluorometers today
Fluorometer
by Wetlabs®
y Virtually all photosynthesizers
use Chl a
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Absorbs light that penetrates deepest
y Chl b common in cyanobacteria
y Chl c common in diatoms and coccolithophorids
y Dinoflagellates have other accessory pigments
y Further IDs require high‐pressure
liquid chromatography
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Photosynthesis‐“lite” (simplified)
How does photosynthesis work?
Photosynthesis
2 Steps:
1.
Light‐dependent rxns: Convert light E to chem E (ATP)
y E‐releasing pathway
y Requires CO2 & H2O
y Releases O2
y Requires O2
y Releases CO2 & H2O
Photosynthesis –
2.
Aerobic Respiration
y E‐storing pathway CO2 + H2O + light Æ (CH2O) + H2O + O2
(Sugar)
Light‐independent rxns: Respiration –
Use ATP to build sugar
CO2 + H2O + energy Å (CH2O) + H2O + O2
It’s waaay more
complex than this…
Sugars!
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But note the following…
Nutrient Cycling
y Photosynthesizers need energy… even when it’s dark.
y When it’s dark, phytoplankton do respiration!
y Replenishing raw materials
y “Sloppy feeding” and fecal pellets by zooplankton
y Summer = more daylight in N. Hemisphere, so greater net PP
y Winter = less daylight in N.H., so less net PP
Euphausiid (krill)
y Fecal pellets sink faster.
y Vertical migration redistributes C deeper
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A.K. Morris, Ph.D.
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Lecture #15
Week #13
(cont…)
Vertical migration:
y Vertical migration: during day, live at depth (200m) and at night swim to surface to feed
y Where is most of the food?
y Where can predators best see?
y Advantage:
y Avoid predation
y Slow metabolism / save E. in cooler water
y Disadvantage:
y Cannot feed
y Migrating uses E.
y Slow metabolism / cannot develop
y Positive Outcome:
y Largest migration on the planet happens every day
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Transports carbon deep
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Vertical Migrators
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Vertical Distribution Challenges
y Zooplankton:
y Herbivores (and some carnivores)
y Compensation depth vs. Critical depth
y One of the most numerous Fig. 13.13
(Gain)
organisms on Earth
Photosynthesis
Respiration
Copepod
(Loss)
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Vertical Distribution Challenges
Vertical Distribution Challenges
y Compensation depth vs. Critical depth
Photosynthesis
y Compensation depth vs. Critical depth
Fig. 13.13
(Gain)
Fig. 13.13
(Gain)
Photosynthesis
Respiration
(Loss)
Respiration
(Loss)
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Lecture #15
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Seasonal Primary Productivity
Seasonal Primary Productivity
y Limits: light, nutrients.
y Winter: best nutrients
y These things vary seasonally
y Summer: best light
y Spring: best compromise!
Baltic Sea late spring phytoplankton bloom
Aqua/MODIS true-color image, June 38
7, 2005
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Surface
Chlorophyll a
California
Upwelling
y Seasonal upwelling
brings nutrient rich
bottom waters into the photic zone.
y Leaves a temperature signature
y Chlorophyll conc. images mirror temp.
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Notice the Distribution
y Temperate zones
y Upwelling zones
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Lecture #15
Week #13
Fig. 13.16
Iron Enrichment
y Fe recognized as a limiting nutrient by John Martin.
•Cold water
•High nutrients
•Reduced wave action (depth‐related)
•Areas for attachment
y Primary source mainly through wind dispersal
y High‐nutrient,
low‐chl (HNLC)
•Sunlight
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