Corals, Climate, and Sea Level Changes Guest Scientist: Lida Teneva

1. Corals, Climate, and Sea Level Changes Guest Scientist: Lida Teneva Earth2Class Workshops originally presented 9 Feb 2008

2. For most people, coral reefs are ecosystems teeming with exotic lifeforms Brightly-colored fish, sharks, moray eels, and waving seaweeds are the more obvious members of a reef community Underlying all are the many species of corals http://barbiemail.googlepages.com/home Coral reefs should have as much diversity as tropical rainforests.

3. Colonial animals in the Phylum Cnidaria (Coelenterata) Radially symmetric Sac-like polyps Stinging tentacles Often nocturnal What are corals? http://oceanworld.tamu.edu/students/coral/coral1.htm

4. What is a coral reef? • Reefs are formed by thousands of hard coral colonies growing adjacent to each other • Composed mainly of calcareous secretions from the coral, coraline algae, and sand; • Only occur in waters where the minimum average monthly temperature is 18 degrees C or higher • There are cold water corals, but not reefs

5. What do corals need? • Sufficient light for zooxantheallae • Appropriate water temperatures and salinity • Suitable currents to bring nutrients and remove wastes • Adequate dissolved O2 • Viable range for CO2 and other factors influencing seawater pH

6. Formation of reefs plays an important role in the Carbon Cycle http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/CarbonCycle.html

7. So, of particular concern are effects of ocean acidification • Carbon dioxide from the atmosphere dissolves in the ocean, and makes it acid. • This is inevitable with high carbon dioxide, no fancy models are involved. • The oceans are already 30% more acid that before fossil fuel burning started • Acidification will kill corals, and probably make many other species (like squid) extinct • The overall effects are unknown - there has been no period like this in the last 2 Million years http://www.geos.ed.ac.uk/ccs/Technical/Ocean/

8. But pollution, overfishing, overuse, and climate change threaten reefs worldwide. Human have already destroyed an estimated 10% of the world’s reefs through direct and indirect activities. For more about this:http://oceanworld.tamu.edu/students/coral/coral5.htm http://oceanworld.tamu.edu/students/coral/images/reef_peril_2.jpg

9. IYOR: International Year of the Reef http://www.iyor.org/

10. Threats to Coral Reefs • How come they are in danger? • So what are the different things we are doing to damage coral reefs? • How are corals affected by climate change? • What other things are damaging coral reefs?

11. Coral Reef Bleaching Natural and anthropogenic changes in a reef environment may lead to “bleaching,” a condition that occurs when photosynthetic zooxantheallae die. There has been significant increase in such events during the past two decades. http://www.reeffutures.org/topics/bleach.cfm

12. http://www.marinebiology.org/coralbleaching.htm

13. Monitoring Coral Reefs Direct observations by divers and boats Satellite observations • http://barbiemail.googlepages.com/monitoring

14. Changes in Sea Level One of the most significant potential impacts of climate change is sea level rise that may cause inundation of coastal areas and islands, shoreline erosion, and destruction of important ecosystems such as wetlands and mangroves. As global temperatures increase, sea level rise already underway is expected to accelerate due to a thermal expansion of upper layers of the ocean and melting of glaciers. http://www.climate.org/topics/sealevel/index.shtm l

15. LDEO Research into how Corals Serve as Recorders for Climate and Sea Level Change LDEO scientists have studied “drowned” coral reefs in Barbados and nearby Caribbean islands. Changes in sea level that occur too fast for coral growth to adjust “drown” reefs. These can be located and cored to develop a “curve” recording sea level changes. Radioisotopes are used to “date” the patterns. http://radiocarbon.ldeo.columbia.edu/research/sealevel.htm

16. More about Corals and Paleoclimatology • Collecting coral cores • Corals and the threat of global climate change • Corals and Tropical Pacific climate variability: The El Niño-Southern Oscillation (ENSO) http://www.ncdc.noaa.gov/paleo/outreach/coral/coralintro.html

17. Example of a Coral Core This is a segment of a coral core obtained from Urvina Bay, Galápagos. The black lines represent annual bands, while the blue and red lines subdivide the year into quarters. http://www.ncdc.noaa.gov/paleo/outreach/coral/corepic.html

18. After our break, Lida Teneva will explain much more about the research she and colleagues have conducted into these problems, and later lead a tour through some of the Lamont lab facilities devoted to finding answers to these questions.