Baier, C. T. University of Washington, Joint Institute for Study of the Atmosphere and Ocean, cbaier@afsc.noaa.gov
Napp, J. T. NOAA/NMFS/AFSC, jnapp@afsc.noaa.gov

 
DISTRIBUTION, REPRODUCTION, AND DEVELOPMENT OF CALANUS MARSHALLAE IN THE SOUTHEASTERN BERING SEA DURING THREE YEARS OF CONTRASTING OCEANOGRAPHIC CONDITIONS
 
Calanus marshallae dominates the mesozooplankton biomass of the southeastern Bering Sea Middle Shelf Domain. Naupliar and copepodid stages of this copepod are preferred prey for young walleye pollock, an important food species for higher trophic levels, including humans. Therefore, environmentally-induced changes in the magnitude and timing of production by C. marshallae may strongly affect the Bering Sea Shelf ecosystem and its commercial fisheries. We compare the springtime abundance, gonadal maturity, and stage distribution of C. marshallae copepodites during 3 consecutive years of varying southern sea ice extent. Maximal, average, and minimal ice cover occurred in 1995, 1997, and 1996, respectively. In 1997, anomalous weather caused major biophysical perturbations over the Shelf. In situ egg production rates at temperatures from -1 to +5 degrees C ranged from 8-31 eggs female-1 day-1, with mean clutch sizes of 22-47 eggs. These results were combined with gonadal maturity and female abundance data to estimate total daily egg production. Our results suggest that initiation of egg production by C. marshallae is not strongly dependent on the Spring phytoplankton bloom, but may be fueled by omnivory, lipid stores, or both.
 
Day: Wednesday, Feb. 3
Time: 02:45 - 03:00pm
Location: Hilton of Santa Fe
 
Code: CS66WE0245H