TITLE:     Modeling of Light-Saturated Photosyntheis in Antarctic Coastal
           Waters
AUTHOR:    HM Dierssen, RC Smith and M Vernet
DATE:      12-16 Feb 1996
PLACE:     1996 Ocean Sciences Meeting, San Diego, California
 Eos, Transactions, American Geophysical Union, Vol. 76, No.3, January 16, 199
 ASLO Feb96

ABSTRACT:  
The Southern Ocean is a high latitude ecosystem with pronounced
seasonal variability in incoming solar radiation.  Extensive 
cloud cover provides further variability and reduces surface radiation 
by about 40-50% annually.  Consequently, it has been thought that 
light availability may limit productivity in the Southern Ocean.  
Using measurements of photosynthetically available radiation (PAR) 
collected over the course of five years at Palmer Station, we present 
evidence that antarctic phytoplankton are generally not limited by 
light and are operating primarily under conditions of light saturation 
during the growth season (November to March).  Both photosynthesis-
irradiance (PI) parameters collected historically in the waters off the 
Antarctic Peninsula and recently by the Palmer Long-Term Ecological 
Research (LTER) program are used in the analysis.  The implications 
of light-saturation are evaluated in terms of the temporal variability 
in the light utilization index, $\Psi$, and its use in estimating 
integrated rates of primary production.  We conclude with an analysis 
of how bio-optical production models may be refined to account for 
light-saturated production.