Ocean Acidification: The Other CO 2 Problem

1. Ocean Acidification:The Other CO2 Problem Dr. Scott C. Doney Oceanographer and Biochemist • A.G. Huntsman Award for Excellence in Marine Science • American Association for the Advancement of Science (AAAS) Fellow • American Geophysical Union Fellow • National Science Foundation Graduate Fellowship

2. Let’s start with the basics… What is Ocean Acidification? • The current process that is occurring due to the anthropogenic addition of carbon dioxide in seawater that causes a reduction in ocean pH and shifts in carbonate speciation

3. Seawater is naturally BASIC at about ~8.1 on the pH scale

4. Important figures to keep in mind • AVERAGE Seawater pH has dropped about o.1 units (8.21 to 8.10) since pre-Industrial times. • This seemingly small change translates into a 30% increasein acidity. • The oceans absorb about 30%-40% of atmospheric CO2. • Air-sea gas exchange equilibrates surface water CO2 to atmospheric levels with a timescale of approximately one year Video http://sos.noaa.gov/videos/pH.mov

6. Why is increased ocean acidity a problem? video.html

7. Calcium Carbonate: The Building Block of the Oceans • Increases in CO2causes a decrease CACO3 saturation states • Calcium Carbonate is very important to marine calcifying organisms(Plankton, coral, coccaliths), and is essential to the formation of shells. CACO3 Aragonite Calcite

9. What is Ω? • Omega is the Saturation State of a mineral, or the tendency for a mineral to either form or dissolve. • Saturation states are higher in warm, shallow tropical water and lower in deep, cold, high latitude regions. • Ωvalues greater than one mean that a mineral is likely to form • Ω values less than 1 mean that a mineral will dissolve

10. http://sos.noaa.gov/videos/saturation.mov

12. Various Effects on Marine Organisms • In calcifying organisms such as coral, an increase in acidification will cause a decrease in calcification and growth, and in some cases even dissolution (existing corals may dissolve) • Aragonite Saturation Horizon line will become more shallow, putting deep-sea coral at risk • Other calcareous organisms are believed to be at similar risks, but more research outside of coral is still needed • In several photosynthetic organisms such as phytoplankton, photosynthetic rates were unchanged by acidity • Other photosynthetic organisms such as some diatom species exhibited increased rates of photosynthesis. • Some sea grass the forms habitats for fish thrived in waters with greater concentrations of dissolved carbon dioxide.

13. Effects on Coral Reefs Before Increased Acidity After Corrosion

14. Potential Organism Adaptation Evidence of sudden coral appearance after widespread benthic extinction 14 mya, suggesting coral survived but without protective skeletons One species of coccaliths exhibited an increase in size under higher CO2 concentrations. Growth rates, however, were reduced.

16. Future Projections? • Not a great time to be a fish • Overwhelming acidification rates • Tune into Karen for more scary numbers

17. My Opinion.. • Article was well written. Covers what is known about acidity as well as shortcomings in research to date. • Negative effects of increased acidification have been established and accepted. • It is urgent that scientists now focus research possible adaptations strategies of marine organisms

18. Finally! A Summary! • Anthropogenic increases in CO2 are increasing acidity in the oceans. • This acidity is harmful to the creation of aragonite, a calcium carbonate mineral, which puts calcifying organisms at risk. • There are some cases of adaptation in marine organisms to these corrosive environments. • Further research is needed to investigate effects on other organisms such as photosynthetic organisms. • Food-chain processes put humans at risk if habitats and primary producers decrease.