Simpson, E. University of Alaska Fairbanks, psimpson@ims.uaf.edu
McRoy, C. University of Alaska Fairbanks, ffcpm@aurora.uaf.edu

 
MODEL EVIDENCE OF A BERING SEA IRON CURTAIN
 
The iron curtain hypothesis states that a transition region of increased production exists between iron replete region near shore and iron limited regions offshore. This hypothesis postulates that such an iron limited region exists. Iron limitation has not been specifically measured in the Bering Sea as yet, but the iron curtain hypothesis has been invoked to explain the persistent high chlorophyll zone at the Bering Sea slope. Phytoplankton growth and nutrient utilization during the onset of the spring bloom in the eastern Bering Sea are estimated using a 1D biological model. The semi-analytical model is similar to a model capable of realistically simulating chlorophyll, nutrient and zooplankton concentrations over the Bering Sea shelf and Prince William Sound. Light and winds are as experienced during a cruise of the Bering Sea basin/slope region during the first two weeks of April 1997. Fresh water is added to the surface layer to reproduce the ice melt observed during the cruise which has been postulated as the likely cause of the early spring bloom that year. The model is initially run as it would be over the shelf and in Prince William Sound, assuming an abundance of dissolved iron and no micrograzers. The model produced chlorophyll concentrations and macronutrient depletion greater than observed over the basin while reproducing the values observed over the outer shelf. The model can reproduce values observed over the basin by incorporating either iron limitation or micrograzers over the basin. Both mechanisms may be at work in the Bering Sea.
 
Day: Friday, Feb. 5
Time: 09:45 - 10:00am
Location: Sweeney Center
 
Code: CS55FR0945S