HR: 08:45h
AN: OS11B-04    [Abstracts]
TI: Does the Columbia River Plume Influence Copepod and Euphausiid Biomass and Growth Rates in Continental Shelf Waters off Washington and Oregon?
AU: * Peterson, W T
EM: bill.peterson@noaa.gov
AF: NOAA-Fisheries, Hatfield Marine Science Center 2030 S. Marine Science Drive, Newport, OR 97365
AU: Feinberg, L
EM: leah.feinberg@noaa.gov
AF: Cooperative Institute for Marine Resource Studies, Hatfield Marine Science Center 2030 S. Marine Science Drive , Newport, OR 97365
AU: Shaw, T
EM: tracy.shaw@noaa.gov
AF: Cooperative Institute for Marine Resource Studies, Hatfield Marine Science Center 2030 S. Marine Science Drive , Newport, OR 97365
AB: We have been making hydrographic measurements and sampling the zooplankton and juvenile salmonids along a grid of stations off Washington (WA) and Oregon (OR) in June and September from 1998 to present. We have found that upwelling is weaker off WA state as compared to OR, but that chlorophyll concentration is on average three times higher than off WA than OR. Given the higher biomass of phytoplankton, are zooplankton biomass and production rates higher off WA? With funding from the National Science Foundation (the RISE program) we have been evaluating this question through measurement of copepod and euphausiid biomass, egg production and molting rates. We have not found a consistent difference in copepod biomass off WA as compared to OR, but have found that the concentration of euphausiid eggs is nearly an order of magnitude higher off WA than OR. From one cruise in June 2003, we did not find a significant difference in copepod {\it(Calanus marshallae)} egg production rates between stations off WA as compared to OR, probably because phytoplankton concentrations were very high in both regions thus did not limit copepod growth. We found a significant correlation between copepod egg production and water depth, regardless of latitude with egg production rates highest inshore and lowest offshore. Thus although there were large differences in chl-a between WA and OR, the onshore-offshore differences are more important in controlling egg production rates than alongshore differences.
DE: 4815 Ecosystems, structure and dynamics
DE: 4855 Plankton
DE: 4279 Upwelling and convergences
DE: 4516 Eastern boundary currents
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting