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to live Life as a Polar Oceanographer you need..
To be a scientist...
Get a ship...
find some ice...
form a team.
and love life
polar bears in the Arctic
penguins in Antarctica
Barbara Prézelin, UCSB 2002
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Understanding Predicting the UVR Ecology of
Phytoplankon Consequences for Marine Primary
Production Advances Challenges Barbara
Prézelin, UCSB 2002 Fact Primary production by
phytoplankton is of major importance to marine
ecosystem dynamics, and to global climate via the
drawdown of atmospheric CO2. Understanding
phytoplankton photoecology is central to
understanding food chain dynamics, biogeochemical
cycling, community structuring and other large
scale physical/biological/chemical ocean
processes.
Arctic food web
Barbara Prézelin, UCSB 2002
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Fact Largely for practical reasons, estimates
of primary production are based on estimates of
carbon fixation rates due to PAR only
P 0.66125 PBopt x Chl(0) x DIRR x Zeu x Eo /
(Eo 4.1)
PPmax tanh I/IK
Fact Photoinhibition by UVR alters PAR-based
measurements of P-I curves, lowering radiation
utilization efficiencies and increasing
sensitivity to photoinhibition by PAR
Fact Photoinhibition by high intensity PAR is
observed in some P-I curves and can be treated as
a loss term.
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Fact Ultraviolet radiation (UVR, 100-400 nm)
is only a small part of the solar spectrum but it
is the most energetic non-ionizing radiation
reaching the earth and penetrating the ocean
surface.
100-280 nm UVC 280-320 nm UVB 320-400 nm
UVA
only gt295 nm sunlight reaches the earths
surface
Barbara Prézelin, UCSB 2002
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Examples of underwater UV light fields in
different water masses in the Santa Barbara
Channel
295--320 nm UVB 320-400 nm UVA
Experimental drifters
Progression from UVBUVAPAR to UVA PAR to PAR
only with depth because intensity of UVB, UVA,
PAR decreases with depth but at different rates.

• What explaination(s) could account the difference
  between the 2 graphs?
• If same site, measured on different days ?
• If sites were side by side and measurements made
  on the same day?

Barbara Prézelin, UCSB 2002
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Fact Ultraviolet radiation (UVR, 100-400 nm) is
only a small part of the solar spectrum but it is
the most energetic non-ionizing radiation
reaching the earth and penetrating the ocean
surface.
Absorption spectra for phytoplankton pigments,
proteins and DNA..
At what depth in the light field graphs would
these bio-markers be safe from UVR?
100-280 nm UVC 280-320 nm UVB 320-400 nm
UVA
only gt295 nm sunlight reaches the earths
surface
Barbara Prézelin, UCSB 2002
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Fact In phytoplankton, UVR effects are numerous
diverse. The major targets for UV-B damage are
DNA integrity, PS II functionality, the
photoprotective processes being induced by UVA
radiation.
Photoprotective carotenoids

• targets for UV-B damage
• DNA damage or destruction
• Photosystem II destruction
• RUBISCO pool level or specific activity?
• Disruption of UVA-Induction of MAAs (sun
  screens)
• Disruption of UVA- Induction of photoprotective
  carotenes
• Disruption of ATP synthesis
• Disruption of cell membrane structural
  integrity
• Respiration and metabolic changes
• Cell behavior and morphology ?

Barbara Prézelin, UCSB 2002
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• Facts
• UV-B radiation impacts the vitality of many
  organisms within
  aquatic food webs.
• UV-B photochemistry plays an important role in
  DOC dynamics and trace gas releases from the ocean

Where do your research interests lie within the
aquatic food web?
W. Vincent
Barbara Prézelin, UCSB 2002
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• Serious Complication
• Inhibition by UVR reaching and penetrating the
  oceans is exacerbated by recent and ongoing
  depletion of stratospheric ozone, which causes
  commensurate increases in surface UV-B.

A) Total Arctic O3 during spring for last 30 yrs
B) Total Antarctic O3 during austral spring for
last 50 yrs
1979-1989
C) For every 1.0 decline in O3 there is a
1.1 increase in UV-B radiation reaching the
Ocean surface and a 1.3 increase in DNA
damaging radiation
Barbara Prézelin, UCSB 2002
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Estimates of increase in sunburning UVR between
1979 to mid 1990s due to increases in
ozone-dependent UVB radiation reaching the earth
surface.
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This outdoor design can simulate spectral
properties of in situ surface but not
subsurface light fields
Red tide dinoflagellates
Barbara Prézelin, UCSB 2002
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Fact A good deal of new knowledge can be
derived from simple UVR experiments and where the
spectral irradiances are not known. For
instance, consider the following experiment that
measured carbon fixation rates and chlorophyll
biomass in replicate samples screened with
different spectral UVR cutoff filters.
What might also be learned by repeating this
experiment at a different time, length of
incubation, location, with grazers, with cDOM
additon, etc?
Barbara Prézelin, UCSB 2002
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Oceanographic procedure for UVR experiments with
natural phytoplankton communities
Barbara Prézelin, UCSB 2002
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Fact There is overwhelming evidence that UVR (
295-400 nm in nature) inhibits production
photoregulates phytoplankton production
community ecology, with implied but unkown
consequences for ecosystem dynamics in polar,
temperate tropical seas.
IUVB IUVA EUVA REFERENCE __________
__________________________________________________
_____________ ANTARCTIC PHYTOPLANKTON
under the ozone hole Pelagic 5 -60
0-60 0-15 Smith et al. 1992 cf. Prézelin
et al. 1994a,b Under ice
5-40 10-40 0-8 cf. Prézelin et al.
1996 Ryan Beaglehole 1994 Mc Minn et
al. 1999 Littoral 3-80
3-17 1-20 Evens et al. 1994
diatoms ARCTIC / SUBARCTIC
PHYTOPLANKTON Pelagic gt20 Helbling et
al. 1996 lt--30-70--gt EilertseHol
m-Hansen 2000 TEMPERATE/SUB-TROPICAL (Prézelin
et al., in prep) site 1
6-21 0-18 0-16 winter site
2 16-22 1-11 0-6 winter site 1
8-24 0-10 9-21 June site 2
6-25 1-21 0-21 June site 1
0-13 0-16 0-28 Aug-Sept site 2
0-31 2-33 0-55 Aug-Sept site 1
0-22 0-16 2-35 Dec site 2
0-6 0-12 0-7 Dec
Barbara Prézelin, UCSB 2002
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Comparison between O3-dependent UVB Inhibition of
in situ Primary Production for coastal waters of
California and the west Antarctic Peninsula
Total UVB exposure
Prezelin et al. in prep.
Barbara Prézelin, UCSB 2002
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Ad
Antarctica the ice-dominated continent surrounded
by the Southern Ocean
Barbara Prézelin, UCSB 2002
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Fact Arctic O3 climatology, hence UV-B
climatology, are very different from the
Antarctic. Results of UV studies from one
polar region may not apply entirely to the
other the same is true of different locations
within each polar region.
Antarctica
Losses occur within a strong polar vortex which
breaks down as temperature rises and the O3 poor
air is released to mix with global air masses.
Arctic
It now appears that O3-poor air masses are
imported to the arctic from lower latitudes. In
very cold years when stratospheric clouds are
observed, or when particles are injected into the
stratosphere (eg by volcanoes), major O3
depletion will also occur inside the Arctic
circle.
Hint Knowing about the O3 /UV-B changes
occurring over your study site allows you to ask
better questions, design better experiments,
and put the results in a larger perspective.
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Oceanographic procedure for UVR experiments with
natural phytoplankton communities
Barbara Prézelin, UCSB 2002
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Icecolors 90 at low irradiances, UVA has a
very small enhancement effect on Antarctic
PP Above a threshold , the net effect of UVA
exposure is inhibition of PP UVA inhibition is
largely dose dependent, reaching gt60 in the
Phaeocystis-dominated waters of the
Bellinghausen Sea in 1992
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Icecolors 90 UVB inhibition figure
See Smith et al. 1992.. Reading assignment
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Fact A working descriptive model of components
photoregulatory processes underlying UVR
effects on Antarctic phytoplankton growth and
photosynthesis was first presented in 1992.
Since then, the working model, with minor
modification, has been shown to generally
applicable to subtropical and temperate latitude
phytoplankton as well.
Updated from Prezelin et al. 1994
Barbara Prézelin, UCSB 2002
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Understanding Predicting the UVR Ecology of
Phytoplankon Consequences for Marine Primary
Production Advances Challenges Newly
Recognized Fact Studies of in situ primary
production are internally consistent to the
extent that UVR inhibitory effects are largest
for shortest wavelengths (UV-B, 280-315nm), while
longer wavelengths (UV-A, 315-400nm) can
simultaneously inhibit and enhance gross primary
production. UV-A gt380nm is rarely inhibiting
while UV-A enhancement has been detected down to
325nm.. Slow to be Realized Fact Laboratory
studies generally confirm the inhibitory nature
of UVR, but their applicability to in situ
conditions is unclear. New and Largely
Unpublished Results Indicate A high variability
in the UVR spectral sensitivities of
phytoplankton biology has been demonstrated
recently in different phytoplankton assemblages
within the same geographical regions and/or
hydrographic regimes Temperate latitude
phytoplankton can be as or more sensitive to UV-B
inhibition than their counterparts under the
influence of the Antarctic O3 hole. A high
variability in the spectral boundaries and
balance between UV-A enhancement and inhibition
of primary production. .
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Variability in UVR effects at 1 site can be
sorted if one considers
Net UVR effects on Production are comprised of 3
mechanistic components UVA Enhancement of
PP-PAR UVA Inhibition of PP-MAX UVB Inhibition of
PP-MAX
Net UVR effects
UVA Enhancement


Total UVA Exposure
Total UVR Exposure
UVA Inhibition
UVB Inhibition

Total UVB Exposure
Total UVA Exposure
Note bubble color refers to treatment day
bubble size proportional to exposure time
Solid colors 5m samples stripes9m and 18m
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Comparison between O3-dependent UVB Inhibition of
in situ Primary Production for coastal waters of
California and the west Antarctic Peninsula
Total UVB exposure
Prezelin et al. in prep.
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Light, bwf, and biological effectiveness
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Generalized scheme for assessment and
prediction of risk arising from UV radiation
effects on biological processes S. Madronich, NCAR
Barbara Prézelin, UCSB 2002
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Fact The first determinations of BWFs for UVR
inhibition of marine primary production under
natural solar radiation was made for spring
Antarctic diatoms under the influence of the O3
hole (Boucher Prezelin 1996a).
Since then, we have developed an IDL-based BWF
Atchitect code which allows for different
fitting functions, averaging of several
estimates of a single BWF, flexibility in
setting parameters for Monte Carlo error
estimates routinely numbering in the 100,000,
etc. (see web site for details). All of this
effort is required if we are to discern the
differences that may be reflected in BWF shape
and magnitude due to any number of variables.
Barbara Prézelin, UCSB 2002
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Boucher and Prézelin, 1996a
A) Comparison of and B) difference between clear
sky UV spectral irradiances at Palmer Station,
Antarctica, at solar noon on Nov 14, as they vary
when stratospheric O3 is 350, 200 100 DU.
courtesy TUV, Madronich 1993 C) Comparison
of BWFs describing the UV sensitivity of (a)
the Hill reaction in chloroplasts Jones Kok,
1966, (b) oxygen evolution in a leaf Caldwell
et al., 1986, (c) a diatom and (d) a
dinoflagellate carbon fixation rates in
laboratory cultures Cullen et al., 1992, (e)
DNA damage in anchovy eggs and larvae Hunter et
al., 1979, (f) the naked DNA damage Setlow
1974, and (g) carbon fixation in an in
situdiatom-dominated community under the
influence of the springtime Antarctic ozone
hole Boucher Prézelin, 1996a.
Barbara Prézelin, UCSB 2002
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A road map to modeling of UVR-corrected primary
production
1
Palmer Station
2
3
5
4
Barbara Prézelin, UCSB 2002
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Unrecognized Uncertainties UVR effects
are not currently represented in conceptual,
in situ mechanistic satellite-dependent
models of regional global ocean primary
production. UVR effects are not represented in
biogeochemical, ecological system ocean
models. The resulting uncertainties are of
unknown importance.
Boucher and Prezelin, 1996b
Barbara Prézelin, UCSB 2002
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BWFs for UV Inhibition of Primary Production For
Antarctic Diatoms under Ozone Hole Incubated
for Different Intervals of a Day September
16, 1993
Barbara Prézelin, UCSB 2002
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Fact The spectral sensitivities of a single
phytoplankton community to UVR inhibition of
carbon fixation can change. Here, BWF samples
were collected every 2 hrs over the course of one
day.

• Sensitivities to UV-B inhibition increased by
  several orders of magnitude from dawn to early
  afternoon and only partly recovered by dusk.
• Sensitivities to UV-A inhibition were about at
  the same between dawn and early afternoon,
  falling in intensity and wavelength by the end of
  the day

Barbara Prézelin, UCSB 2002
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Fact UV-A radiation can, by different
mechanisms, enhance and inhibit rates of primary
production and the net effect is measured in the
BWF. For instance, below is a comparison of BWFs
determined every few hours over one day for
freshly collected in situ Antarcctic diatoms.
Barbara Prézelin, UCSB 2002
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The near future.. UV corrected production models
from space Scheme from Prezelin and Madronich,
unpubl.
Barbara Prézelin, UCSB 2002