TITLE:    Primary Productivity of the Southern Ocean and 
          the Palmer Long Term Ecological Research Area

AUTHOR:   Raymond C. Smith, Karen S. Baker, M.L. Byers & S.E. Stammerjohn

MEETING:  Carbon Fluxes and Dynamic Processes in the Southern Ocean:
	  Present and Past

DATES:    28-31 August 1995

PLACE:    Brest, France


ABSTRACT: A major objective of the Palmer Long Term Ecological Research
(Palmer LTER) project is to obtain a comprehensive understanding of the 
interactions of the interannual variabilty in sea ice concentrations with 
the various components of the Antarctic marine ecosystem.  Phytoplankton
production plays a key role in this so-called high nutrient low 
chlorophyll environment and factors that regulate this production 
include those that control cell growth (light, temperature, and 
nutrients) and those that control the accumulation rate of cells and 
hence population growth (water column stability, grazing, and sinking).
Sea ice mediates several of these factors and frequently conditions 
the water column for a spring bloom which is characterized by a pulse 
of production restricted in both time and space.  This study models the 
spatial and temporal variability of primary production within the Palmer 
LTER area, the area west of the Antarctic Peninsula, and discusses this 
production in the context of historical data for the Southern Ocean.
    Primary production for the Southern Ocean and the Palmer LTER area 
have been computed using both light-pigment production models (Bidigare 
et al., 1987; Morel & Berthon, 1989) and an ice edge production model 
(Smith & Nelson, 1986).  Chlorophyll concentrations, total 
Photosynthetically Available Radiation (PAR), and sea ice concentrations 
were derived from satellite data.  Chlorophyll, PAR, sea ice and 
hydrodynamic conditions have also been determined from shipboard and 
Palmer station observations during the LTER program.  Results of the
sea ice model show some evidence of a persistent 6 to 8 year cycle, 
where consecutive high ice years for the Palmer LTER area (1979-82, 
1986-87 and 1991-92) alternate with low ice years (1983-85, 1988-90, 
and 1993-94). Model results are compared, sensitivity studies evaluated, 
and productivity of the LTER region is discussed in terms of its space 
time distribution, seasonal and interannual variability, possible 
controlling processes, and overall contribution to the marine ecology 
of the Southern Ocean.