marine productivity_mest 2013
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Marine Product iv i ty
By Dr. Nita Rukminasari
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Outlined Lectured
Productivity vs biomass
Food chain
Food web and trophic dynamic
Transfer energy between trophic level
Ocean food web
Primary productivity
Regional productivity Measuring primary productivity
Geographic variation of productivity
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Product iv i ty vs biomass
Biomass the mass of living material
present at any time, expressed as gramsper unit area or volume
Productivity is the rateof production ofliving material per unit time per unit area
or volume
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Product iv i ty
Primary productivity - productivity due to
Photosynthesis
Secondary productivity - productivity due t
consumers of primary producers
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Food Chain
Food chain - linear sequence showing
which organisms consume which otherorganisms, making a series oftrophic lev
Food web - more complex diagram showifeeding relationships among organisms, n
restricted to a linear hierarchy
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Food Chain Abstract ion
Adult
herring
Phytoplankton
Barnaclelarvae
Mollusk
larvae Smallcopepods
euphausid tunicate
cladocerans
amphipodsand eel
Young herring
arrowworm
Larger
copepod
Phytoplankton
Copepod
Herring
Food chain Food Web
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The word
trophic
refers tonutrition. Trophic dynamics is the study of the nutritional
interconnections among organisms within an ecosystem.
Trophic level is the position of an organism within the trophicdynamics.
Autotrophs form the first trophic level.
Herbivores are the second trophic level.
Carnivores occupy the third and higher trophic levels.
Decomposers form the terminal level.
A food chain is the succession of organisms within an
ecosystem based upon trophic dynamics. (Who is eaten by
whom.)
Food Webs and Trophic Dynamics
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Trans fer Between Troph ic
LevelsTransfer from one trophic level to the
next is not complete:
1. Some material not eaten
2. Not all eaten is converted with 100%
efficiency
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Trans fer Between Troph ic
Levels2Budget for ingested food (use energy units
I = E + R + G
I amount ingested
E amount egestedR amount respired
G growth (partitioned between somatic
growth and reproduction)
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Trans fer Between Troph ic
Levels3Incomplete transfer up a food chain:
Measure by food chain efficiency:
E = amount extracted from a trophic level
amount of energy supplied to that leveOften in range of as little as 10%
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Trans fer Between Troph ic
Levels4Use food chain efficiency to calculate
energy available to highest trophic level:
P = BEn
B = primary productionP= production at highest level
E= food chain efficiency
N= number of links between trophic levels
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Trans fer Between Troph ic
Levels4Use food chain efficiency to calculate
energy available to highest trophic level:
P = BEn
Let E = .1, B = 1, n = 2,3,4If n = 2, P = ?
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Trans fer Between Troph ic
Levels4Use food chain efficiency to calculate
energy available to highest trophic level:
P = BEn
Let E = .1, B = 1, n = 2,3,4If n = 2, P = ?
P = 1 x (0.1)2 = 1 x 0.01 = 0.01
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Trans fer Between Troph ic
Levels4Use food chain efficiency to calculate
energy available to highest trophic level:
P = BEn
Let E = .1, B = 1, n = 2,3,4If n = 3, P = ?
P = 1 x (0.1)3 = 1 x 0.1 x 0.1 x 0.1 = 0.001
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Trans fer Between Troph ic
Levels5Use food chain efficiency to calculate
energy available to highest trophic level:
P = BEn
With 5 trophic levels, a change ofEfrom0.1 to 0.2 magnifies Pby a factor of 16
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Ocean ic Food Webs
Food webs in the oceans vary
systematically in food chain efficiency,
number of trophic levels, primary
production
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Ocean ic Food Webs
Food
Chain
Type
Primary
Productivit
y
gCm-2y-1
Trophic
Levels
Food
Chain
Efficiency
Potential
Fish
Production
mgCm-2y-1
Oceanic 50 5 10 0.5
Shelf 100 3 15 340
Upwelling 300 1.2 20 36,000
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Ocean ic Food Webs
Food
Chain
Type
Primary
Productivit
y
gCm-2y-1
Trophic
Levels
Food
Chain
Efficiency
Potential
Fish
Production
mgCm-2y-1
Oceanic 50 5 10 0.5
Shelf 100 3 15 340
Upwelling 300 1.2 20 36,000
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Ocean ic Food Webs
Food
Chain
Type
Primary
Productivit
y
gCm-2y-1
Trophic
Levels
Food
Chain
Efficiency
Potential
Fish
Production
mgCm-2y-1
Oceanic 50 5 10 0.5
Shelf 100 3 15 340
Upwelling 300 1.2 20 36,000
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Ocean ic Food Webs
Food
Chain
Type
Primary
Productivit
y
gCm-2y-1
Trophic
Levels
Food
Chain
Efficiency
Potential
Fish
Production
mgCm-2y-1
Oceanic 50 5 10 0.5
Shelf 100 3 15 340
Upwelling 300 1.2 20 36,000
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Ocean ic Food Webs
Note: Great potential of upwelling areas
due to combination of high primary production,
higher food chain efficiency, lower numberof trophic levels
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Ocean ic Food Webs
Stable, low nutrient Turbulent, hi h nutrient
Few trophic
levels
Many
trophic
levels
Open ocean,gyre centers
Shelf,upwelling
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Primary productivity
Primary productivity is the amount of
carbon (organic matter) produced by
organisms Mostly through photosynthesis
Energy source = solar radiation
Also includes chemosynthesis Energy source = chemical reactions
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Photosynthetic productivity
Figure 13-1
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Oceanic photosynthetic
productivity Controlling factors affecting
photosynthetic productivity:
Availability of nutrients Nitrates
Phosphates
Iron
Amount of sunlight Varies daily and seasonally
Sunlight strong enough to supportphotosynthesis occurs only to a depth of 100meters (euphotic zone)
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Locations of maximum
photosynthetic productivity Margins of the oceans
Abundant supply of nutrients from land
Water shallow enough for light to penetrateall the way to the sea floor
Upwelling areas
Currents hoist cool, nutrient-rich deepwater to the sunlit surface
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Coastal upwelling
Figure 13-3
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The electromagnetic spectrum
and light penetration inseawater
Figure 13-4
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Water color and life in the
ocean Ocean color is influenced by:
The amount of turbidity from runoff
The amount of photosynthetic pigment, whichcorresponds to the amount of productivity
Yellow-green = highly productive water
Found in coastal and upwelling areas(eutrophic)
Clear indigo blue = low productivity water
Found in the tropics and open ocean(oligotrophic)
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Satellite view of world
productivity
Figure 13-6
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Photosynthetic marine
organisms: Plants Seed-bearing
plants
Eelgrass
(Zostera)
Surf grass
(Phyllospadix)
Figure 13-7
Surf grass
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Photosynthetic marine
organisms: Macroscopic algae Brown algae
Sargassum (top left)
Macrocystis (topright)
Green algae
Codium (bottom left)
Red algae
Lithothamnion
(bottom right)Figure 13-8
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Photosynthetic marine
organisms: Microscopic algae Microscopic algae include:
Golden algae Diatoms (silica test resembles a pillbox)
Coccolithophores (calcite plates form a sphericaltest)
Dinoflagellates
Produce a test made of keratin
Posses a whip-like flagella
Bioluminescence
Exist in great abundance, creating red tides
(harmful algae blooms)
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Dinoflagellates and red tides
Figure 13C
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Regional productivity
Photosynthetic productivity varies dueto:
Amount of sunlight
Availability of nutrients Thermocline (a layer of rapidly changing
temperature) limits nutrient supply
Examine three open ocean regions:
1. Polar oceans (>60 latitude)
2. Tropical oceans (
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Productivity in polar oceans
Sunlight peaks in
summer
Nutrients available
nearly year-round
(only weak
seasonalthermocline
develops)
Productivity:
Peaks in spring
Figure 13-10a
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Productivity in tropical oceans
Sunlight strongyear-round
Nutrients limitedby strong,permanentthermocline
Productivity: Steady, low rate
Limited bynutrients
Exceptions:
Figure 13-11
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Productivity in temperate
oceans Sunlight varies
seasonally
Nutrientslimited bythermocline
Productivity:
Spring bloomlimited bynutrients
Fall bloom
limited bysunlight Figure 13-12
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Productivity in tropical,
temperate, and polar oceans
Figure 13-13
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Measu r ing Primary
Product iv i ty
Gross primary productivity - total carbon fix
during photosynthesis
Net primary productivity - total carbon fixed
during photosynthesis minus that part whicis respired.
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Measu ring Primary
Product iv i ty2
Net Primary productivity most interesting:
gives that part of the production available tohigher trophic levels
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Measu ring Primary
Product iv i ty3Oxygen technique -
Principle - relies upon fact that
oxygen is released during photosynthesis
CO2 + 2H2O ---> (CH2O)n + H2O + O2
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Measu ring Primary
Product iv i ty4Oxygen technique 2 - there is an addition frphotosynthesis and a subtraction from
respiration
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Measu ring Primary
Product iv i ty5Oxygen technique 3 -
Measurement of oxygen:
Winkler technique - chemical titration of
Oxygen
Polarographic oxygen electrode -
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Measu ring Primary
Product iv i ty6Oxygen technique 4 -
Light-Dark bottle technique:
Light bottle gives oxygen from photosynth
minus oxygen consumed in respiration
Dark bottle gives oxygen consumed from
Respiration
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Measu ring Primary
Product iv i ty7Oxygen technique 5 -
Light-Dark bottle technique:
Start light and dark bottles with water sample,
a short amount of time
At end of experiment: oxygen in light minus th
dark bottle gives you gross photosynthesis
Measuring Primary Production:
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Measuring Primary Production:
light/dark bottle technique
Take water samples at different depths.
Place one subsample in a transparent (light)
bottle, another in an opaque (dark) bottle.
Resubmerge bottles to original depth. Retrieve after a similar, specified time
(hours)
Measure oxygen, in both Dark bottle: respiratory oxygen consumption
(should be same in both bottles).
Difference in oxygen conc between bottles:
Oxygen technique - effect of depth
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Oxygen technique effect of depth
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Measuring Primary Production Cont.
Problem: if zooplankton present, they will
consume oxygen, even in dark bottle (they arenot primary producers).
Other method: inject water samples with
radioactively-labeled bicarbonate (has C14
). After incubation period, filter phytoplankton
onto filter and measure radioactivity.
Method is very sensitive, measures CO2
takenup; problem: because it is so sensitive, therecan be a high margin of error.
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Measuring Primary Productivity-Cont.
Radiocarbon technique
Principle: carbon is taken up by cells During
photosynthesis, so if you label that carbon you
can trace it as it is incorporated into cells duringphotosynthesis.
Method: add bicarbonate to solution With
phytoplankton that is labeled with 14C
Incubate phytoplankton in the radiocarbon SolutionThen filter phytoplankton and count radiocarbon
Taken up by phytoplankton, using a scintillation
counter
Radiocarbon technique Cont
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Radiocarbon technique Cont.
Calculation:
1. Know the amount of bicarbonate that was in
container2. Know the amount of radiolabeled bicarbonate you
added and the amount that was taken up by
Phytoplankton allows calculation of amount ofbicarbonate taken up in photosynthesis
Correction:14C is taken up more slowly than much more common
stable isotope 12C. Therefore, need to multiplyresults by 1.05 to get amount in photosynthesis
What you get with this measure: Carbon
incorporation into phytoplankton (net
photosynthesis)
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Compare Oxygen technique
with radiocarbon Oxygen technique - used where primaryproduction is high in estuaries, shelf
Radiocarbon technique - useful where primary
production is low such as open ocean
Oxygen technique tends to give higher
estimates of primary production, perhaps
because cells are leaking sugars duringphotosynthesis, resulting in loss of
radiocarbon when cells are filtered and
counted
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Other Methods: Chl a
Chlorophyll a measurements.
Chl a concentration only roughly approximates
primary productivity.
Better used as an indicator of standing crop (i.e., you
are measuring a population, not an activity, not allthe population is involved in the activity).
If your population doesnt change, does that mean no
primary production is occurring? Nope
Balanced turnover rate: rate at which new
production replaces that lost to grazing, settling, etc.
(typically rapid: daily doubling).
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Satellite Approaches:
Satellites can use photometers specific
to
wavelength to measure
chlorophyll,Seawater temperature
Need ground truthing to get relationship
Between chlorophyll concentration and
primary production; varies with region
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sun
Satellite
ColorscannerIrradiance
Radiance
Phytoplankton
Ship based vs Satellite Sampling
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Ship-based vs. Satellite Sampling
Obviously, you miss a lot between widely-
based sampling stations.
Scientists resorted to averaging between
stations and periods: oops!
A lot was missed or lost. Problem solved by remote satellite sensing
using a coastal zone color scanner
(black/white converted to color, color represents level of phytoplankton standing
crops).
Calibrated via ship-based measurements.
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Geographic Variat ion o f
Product iv i ty1. Continental shelf and open-ocean upwelli
Areas are most productive
2. Convergences and fronts often are sitesrise of nutrient rich deep waters (e.g., shallo
water seaward of slope
3. Central ocean, gyre centers are nutrient plow primary production
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South
Pacific
North
Pacific
North
Atlantic
South
Atlantic
Antarctic
IndianOcean
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Satellite image of world productivity, from SeaWiFS satellite
Major Factors Affecting Primary
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Major Factors Affecting Primary
Productivity
Depends on both abiotic and biotic factors/
conditions.
Phytoplankton standing crop would increase
exponentially if nothing was limited.
Populations regulated by tolerance to
limiting factors.
Major ones: light, nutrient availability,
grazing by consumers.
Each major group responds differently to a
different set of conditions.
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2011 Pearson
Education, Inc.
Factors Affecting Primary
Productivity
Solar radiation
Uppermost surface seawater and shallow
seafloor Compensation depth net photosynthesis
becomes zero
Euphotic zonefrom surface to about
100 meters (330 feet)
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2011 Pearson
Education, Inc.
Light Transmission in Ocean
Water Visible light of the electromagnetic
spectrum
Blue wavelengths penetrate deepest Longer wavelengths (red, orange)
absorbed first
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2011 Pearson
Education, Inc.
Transmission of Light in
Seawater
Color in the Ocean
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2011 Pearson
Education, Inc.
Color in the Ocean
Color of oceanranges from deepblue to yellow-green
Factors
Turbidity from runoff Photosynthetic
pigment (chlorophyll) Eutrophic
Oligotrophic
Secchi Disk measureswater transparency
Upwelling and Nutrient Supply
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2011 Pearson
Education, Inc.
Upwelling and Nutrient Supply
Cooler, deeper
seawater is nutrient-rich.
Areas of coastal
upwelling are sitesof high productivity.
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2011 Pearson
Education, Inc.
Upwelling and Nutrient Supply
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Thank you
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