HR: 08:25h
AN: U31A-02    [Abstracts]
TI: Fragile Reefs of the Eastern Pacific: Does low Cementation Provide a Model for Reefs in a High CO₂ World?
AU: * Manzello, D
EM: dmanzello@rsmas.miami.edu
AF: Rosenstiel School of Marine and Atmospheric Science, Univ. of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149, United States
AU: Kleypas, J
EM: kleypas@ucar.edu
AF: National Center for Atmospheric Research, PO Box 3000, Boulder, CO 80307-3000, United States
AU: Eakin, M
EM: mark.eakin@noaa.gov
AF: NOAA Coral Reef Watch, 1335 East West Highway, Silver Spring, MD 20910-3226, United States
AU: Budd, D
EM: budd@spot.colorado.edu
AF: Univ. of Colorado-Boulder, 2200 Colorado Avenue, Boulder, CO 80309-0399, United States
AB: Around the world, reefs will experience high pCO₂, low pH, low carbonate concentrations, and low aragonite saturation state as atmospheric CO₂ rises. Ocean carbon chemistry measurements show that eastern Pacific waters already exist at high pCO₂ and low carbonate concentrations due to natural upwelling in the region. Because of the upwelling, this region may serve as a model for coral reef development under enhanced atmospheric CO₂ and oceanic pCO₂; that is, low coral growth, low secondary cementation, and high physical, chemical, and biological erosion. Reefs in the eastern Pacific Ocean are characterized by low biological diversity and relatively small size. Both past coring and recent analysis reveal that, while many reefs in the eastern Pacific are several thousand years old, they are fragile and lack significant cementation, even in the innermost, oldest structures. They are also extremely porous with high water throughflow. Without secondary cementation, branching coral frameworks are held together only by organically produced calcium carbonate (e.g. coralline algae), sponges, and other reef infauna, and contain a high proportion of loose sediments. The result is reef frameworks that are more susceptible to destruction from mechanical or biological erosion. The poorly cemented nature of eastern Pacific reefs is thus hypothesized to have been a factor in the severe bioerosion that occurred on these reefs after past bleaching events (1982-3, 1997-8). We will present data that indicate low rates of cementation and high rates of erosion on eastern Pacific coral reefs and will compare current carbonate chemistry in the eastern Pacific to model predictions of what reefs around the globe may experience in coming decades.
DE: 0428 Carbon cycling (4806)
DE: 0439 Ecosystems, structure and dynamics (4815)
DE: 0460 Marine systems (4800)
DE: 1615 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 4805, 4912)
SC: Union [U]
MN: 2007 Joint Assembly