HR: 16:00h
AN: PP44A-01    [Abstracts]
TI: Holocene and late Pleistocene Biological processes of the Northwest Pacific Ocean
AU: * Hays, J D
EM: jimhays@ldeo.columbia.edu
AF: Lamont Doherty Earth Obs., Columbia University, Palisiades, NY 10964 United States
AB: The vigor of biological processes at different levels in the late glacial high latitude ocean can be estimated through measuring accumulation rates of deep- and shallow-living radiolarians. Holocene accumulation rates of shallow-living (<200m) radiolarians, measured in two northwest Pacific cores, exceed by two orders of magnitude those of deep-living (>200m) radiolarians. In late glacial time deep- and shallow-living radiolarians accumulate at nearly equal rates. This is due to a drastic reduction of shallow-living and some increase of deep-living species accumulation rate compared with their Holocene rates. Accumulation rates of total opaline silica (mostly diatoms) are higher (10%) in the Holocene than late glacial. These data suggest that northwest Pacific radiolarian consumption of near surface organic matter was reduced and deep-water consumption increased in glacial compared with Holocene time. This would have produced an increase in the efficiency of the biological pump to the degree that radiolarian production is representative of that of other protozoans. Like the late glacial northwest Pacific the neighboring modern Sea of Okhotsk produces high accumulation rates of deep- compared with shallow-living radiolarians and may be a modern analogue of glacial biological processes in the northwest Pacific. Today, unutilized phosphate and nitrate exist in the surface waters of the Bering Sea, northwest Pacific and Antarctic Oceans, however, these nutrients are fully utilized in the modern Sea of Okhotsk. There is therefore evidence of a stronger biological pump in the glacial northwest Pacific and the possibility that this stronger pump and the full utilization of nutrients contributed to the glacial draw down of atmospheric CO2.
DE: 3030 Micropaleontology (0459, 4944)
DE: 4944 Micropaleontology (0459, 3030)
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005