HR: 14:55h
AN: C53A-05    [Abstracts]
TI: Land-sea Coupling in a Changing Arctic: Implications of Increasing River Discharge for Biogeochemical Cycling Over the Eurasian Shelf
AU: * McClelland, J W
EM: jmcclelland@mbl.edu
AF: Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02543 United States
AU: Macdonald, R W
EM: MacdonaldRob@pac.dfo-mpo.gc.ca
AF: Institute of Ocean Sciences, P.O. Box 6000, Sidney, BC V8L4B2 Canada
AU: Holmes, R M
EM: rholmes@mbl.edu
AF: Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02543 United States
AU: Peterson, B J
EM: peterson@mbl.edu
AF: Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02543 United States
AB: While feedbacks between increasing arctic river discharge and global ocean circulation have been highlighted over the past few years, the potential influence of increasing river discharge on biogeochemical cycling in the Arctic Ocean has been given less attention. In this presentation we will evaluate changes in water and nutrient fluxes from major rivers to the Barents, Kara, and Laptev seas from the 1930s to present. Long-term changes in water and nutrient fluxes to these seas are relatively small in comparison to average annual fluxes. However, the changes have not been evenly distributed throughout the year, and account for much larger proportions of average fluxes during some months. In particular, flow regulation from dams on the Ob, Yenisey, and Lena rivers has greatly increased winter discharge. The combined influence of increased winter discharge on stratification, nutrient supply, and spring production in shelf waters will be discussed. Increased stratification is expected to decrease total production. At the same time, the proportion of production supported by river-born nutrients is expected to increase. Nitrate and silicate dynamics will be given particular emphasis. Silicate concentrations are much higher than nitrate concentrations in the Eurasian arctic rivers (and both are relatively low in ocean waters feeding the Eurasian shelf). Thus, changes in silicate supply accompanying increased river discharge have a greater potential than do changes in nitrate supply to influence production in shelf waters. Higher silicate to nitrate ratios would support a shift in the producer assemblage in favor of diatoms.
DE: 4805 Biogeochemical cycles (1615)
DE: 4845 Nutrients and nutrient cycling
DE: 1655 Water cycles (1836)
DE: 1600 GLOBAL CHANGE (New category)
DE: 1615 Biogeochemical processes (4805)
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting