HR: 15:45h
AN: OS52J-06    [PDF]
TI: Past and Present Distribution of Deep-Sea Corals from N Atlantic Seamounts
AU: * Adkins, J F
EM: jess@gps.caltech.edu
AF: Caltech, MS100-23 1200 E. Californai Blvd., Pasadena, CA 91125 United States
AU: Robinson, L
EM: laurar@gps.caltech.edu
AF: Caltech, MS100-23 1200 E. Californai Blvd., Pasadena, CA 91125 United States
AU: Wang, S L
EM: jslw@gps.caltech.edu
AF: Caltech, MS100-23 1200 E. Californai Blvd., Pasadena, CA 91125 United States
AB: Questions of biodiversity in deep-sea corals through geological time have been limited by large numbers of well-dated sample sets. We draw on a recent submersible collection of $>$ 3,000 fossil D. cristagalli, 10s of kgs of Solenosmillia sp. and numerous Enallopsamia rostrata and Caryophilia sp. samples from North Atlantic seamounts (Muir, Manning and Gregg) to make a series of observations on the recruitment, growth history and distribution of these corals over the last glacial cycle. The sample set spans a depth range of 1,150-2,500m, and latitudes of 33\deg45' to 38\deg58'. The abundance of fossil D. cristagalli rapidly decreases at 2,400-2,500m, and was absent down to our deepest dives at 2850 meters, suggesting that at no time were conditions well suited to coral growth at these depths. U series dating of individual corals will enable us to answer key questions on the timing of changing coral populations. For example, both D. cristagalli and Solenosmillia sp. are prevalent in the fossil record, but living samples are extremely scarce, particularly on the most southerly Muir Seamount. Two alternative hypotheses may explain this observation. First, living corals have always been scarce and the large accumulation is the result of a gradual build up of dead coral material over long time periods. Second, these corals were more abundant at some point in the past but subsequent environmental change induced a rapid decline in the population. By contrast, E rostrata is the most abundant living species but is under represented by fossil samples. Histograms of coral ages will allow us to begin to unravel the population history of the New England Seamounts. At the individual level, fossil D. cristagalli were often found to have recruited onto other carbonate skeletons, particularly large branching gorgonians. The U-series age distribution of these recruitment patterns will constrain how much palaeoclimate time a particular patch can represent.
DE: 1620 Climate dynamics (3309)
DE: 4267 Paleoceanography
DE: 4808 Chemical tracers
DE: 4815 Ecosystems, structure and dynamics
SC: Ocean Sciences [OS]
MN: 2004 Ocean Sciences Meeting