Potential Impacts of Ocean Acidification on Coral Reef

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Potential Impacts of Ocean Acidification on Coral
Reef and Calcifying Organisms?ICRI , April, 24,
Tokyo
Yoshimi Suzuki Beatriz Casareto
Shizuoka University,JCRS
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Ocean acidification

• The ongoing decrease in the pH of the oceans has
  been caused by their uptake of anthropogenic CO2
  from the atmosphere
• Over the past 200 years, the pH of surface sea
  water has decreased by 0.1 units (equivalent to
  a 30 increase in the concentrations of H ions)
  
• Increase pCO2, reduces the carbonate ion
  concentration and thus reduce calcium carbonate
  saturation of the seawater
• These processes are affecting the life and
  structure of marine ecosystems and the regulation
  of C cycling.

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Recent research reports

• UNEP WCMC on cold water coral reefs mentions
  atmospheric CO2 as a potential impacts (2004)
• A brief overview report (Hauganhj, 2004)
• was presented to OSPAR
• IOC/SCOR Symposium (May, 2004)
• Royal Society Report (June, 2005)
• US Workshop on impacts on coral reefs
• and other marine calcifiers (April,
  2005)
• 6) First IGBP-SCOR workshop
• Ocean acidification-modern observation
  and past
• experiences (Spt. 2006)
• 7) Second workshop for synthesis (May, 2007,
  France)

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• 1.Ocean acidification is a predictable
  consequence of increased atmospheric CO2.
• 2. Ocean acidification depends on the chemistry
• of CO2.
• 3.Ocean chemistry is changing at least 100 times
• more rapidly than it has changed in the 100,
  000 yrs. preceding our industrial era.
• 4. Ocean acidification could be expected to have
  major negative Impacts on corals and other marine
  organisms that build calcium carbonate shells and
  skeletons.
• 5. Research is needed to better understand the
  vulnerabilities, resilience, and adaptability of
  marine organisms and ecosystems.

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CO2 effects on marine organisms and ecosystems
physiological background and affected
processes Question complete lack of field
observations, scenarios of CO2 effects on
marine ecosystems developed based on laboratory,
mesocosms and model. We have a large gaps in
knowledge, there is considerable demand for
research In this area to reach exact predictabilit
y. Dissolution and changes of photosynthesis
under the lowered pH values are due to the
ability to adapt to Increasing CO2
concentrations on time scales Key processes
are foodweb and adaptation
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Calcification vs dissolution
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pH
Ambient pCO2 400ppm
High pCO2 1000ppm
After 8days, pH was back to more than 8 under
the incubation experiments (organisms cocolith)
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Without grayzer
With grayzer
Chl-a
Cell of Cocolith
Chl-a and biomaas of cocolith Increased under
the high CO2 Concentrations (1000ppmCO2)
Biomass of Cocolith
We expect that abundance of zooxanthellae
increases With increase of CO2 concentration. Is
it right ?
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Gross primary production increased to 40 Gross
calcification increased to 40 More dissolution
CO2
CO2
1.0
1.7
100.8
71.1
157.7
38.0
??
??
GPP
GPP
49.6
29.2
Orgaqnic
Orghanic
7.4
24.1
35.3
4.1
Coral
??
GC
??
GC
28.2
16.7
CaCO3
CaCO3
-2
-1
mmol C m
d
Carbon balance at 450ppmCO2
Carbon balance at 650ppm CO2
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• Ecosystem and organic matter cycling in
  Coral Reef

CO2 increase
Nutrients
Virus
Bacteria
Protozoa

Microzooplanton
phytoplankton
Large zoopllankton

Nitrogen fixation
Fish /Shell
Coral
Bentos
cyanobacteria
Zooxanthelloae

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• Forcing factors
• As pCO2 Is increasing , other environmental
  variables
• will also changes. increased temperature,
  changes
• in availability of nutrients (due to changes in
  redox
• conditions, ocean mixing, patterns of
  precipitation,
• dust inputs, and increased stratification).
• Ecological aspects
• Effects on community structure and
  composition
• Effects on genetic diversity, species
  diversity, and the
• diversity of functional groups
• Will they be able to adapt to the evolve
  quickly enough
• to change now occuring ?
• Can adaptation occur under a continually
  and rapidly
• changing environment verus one that
  eventually
• stabilizes?

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• 2. Key biogeochemical processes
• Primary production Will increasing pCO2
  in
• the surface ocean fertilize phytoplankton
  ?
• For high tropic levels ? C/N/P ratio
  ?
• Remineralization ?
• Nitrogen fixation ?
• DOM transfromations (aggregation,
• solubilization, biological turnover ?)
• Calcification ? Dissolution?
• Role of bacteria and grazer ?

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• 3. Approches on reseaqrch
• Laboratory experiments
• Mesocosm experiments
• Short-term perturbation experiments ?
• Model developments

4. Action plan of ICRI Advanced monitoring
system ( pH, Chl-a, bacteria, nutrients)
Increase of primary producers
(zooxanthellae, cyanobacteria, algae, gravel
etc.) Fertilization of nutrients
(NPSi) Avoiding human pollution
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Subjects in discussion

• 1.How do we get an evidence of impact to
  
• coral reef ?
• Understanding of impacts on coral, sea grass,
  zooxanthellae, fish, benthos, other animals--
• 2. What monitoring is required ?
• Physical, chemical, biological,
  geological,--
• 3. Do we need a new method for conservation
• of coral and coral reef ?
• 4 How to educate an importance of ocean
• acidification ?