HR: 1340h
AN: PP13B-1289    [Abstracts]
TI: Abrupt climate change and collapse of deep-sea ecosystems during the last 20,000 years
AU: * Yasuhara, M
EM: moriakiyasuhara@gmail.com
AF: U.S. Geological Survey, 926A National Center 12201 Sunrise Valley Drive, Reston, VA 20192, United States
AU: Cronin, T M
EM: tcronin@usgs.gov
AF: U.S. Geological Survey, 926A National Center 12201 Sunrise Valley Drive, Reston, VA 20192, United States
AU: deMenocal, P B
EM: peter@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9W, Palisades, NY 10964, United States
AU: Okahashi, H
EM: hyasuhara@usgs.gov
AF: U.S. Geological Survey, 926A National Center 12201 Sunrise Valley Drive, Reston, VA 20192, United States
AU: Linsley, B K
EM: blinsley@albany.edu
AF: Department of Earth and Atmospheric Sciences, University at Albany-State University of New York, DEAS ES351 1400 Washington Avenue, Albany, NY 12222, United States
AB: We investigated high-resolution deep-sea sediment core records of benthic ostracodes during periods of rapid climate and oceanographic change of the last 20,000 years in the Ocean Drilling Program Hole 1055B, western subtropical North Atlantic (32° 47.041'N, 76°17.179'W; 1798 m water depth). Age control was established with radiocarbon and oxygen isotope. Results show that deep-sea benthic community collapses occur with faunal turnover of up to 50 % during all major climatically-driven oceanographic changes. The Shannon-Wiener species diversity index falls from 3 to as low as 1.6 at minimum during these events. Major disruptions of benthic communities occurred during Heinrich Event 1 (16.8 ka), the Intra-Allerød Cold Period (13.1 ka), the Younger Dryas (YD: 12.9-11.5 ka), and several Holocene Bond events. The largest collapse is identified as an abrupt two- step decrease of the North Atlantic Deep Water assemblage and species diversity that occurred at 13.1 and 12.2 ka and is associated with the YD. This collapse of deep-water assemblage and species diversity did not fully recover until ~8 ka. Reduced deep-water formation at intermediate depths (<2000 m) during the deglaciation may have caused the collapse. Similar deep-water slowdowns may also have caused benthic community collapses during Holocene climatic oscillations. These results indicate that deep-sea ecosystems are not immune to the effects of rapid climate changes occurring over centuries or less.
DE: 0410 Biodiversity
DE: 0439 Ecosystems, structure and dynamics (4815)
DE: 4900 PALEOCEANOGRAPHY (0473, 3344)
DE: 4901 Abrupt/rapid climate change (1605)
DE: 4944 Micropaleontology (0459, 3030)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting