TITLE:     Photoacclimation in a coastal phytoplankton bloom and impact on the
           radiation utilization efficiency for carbon fixation
PAGE:      American Society of Limnology & Oceanography (ASLO)
	   1995 Meeting
AUTHOR:    Oscar Schofield, Mark A Moline, Barbara B Prezelin
DATE:      11-15 June 1995
PLACE:     University of Nevada, Reno

Note: See also Lter Contribution #42

ABSTRACT: The temporal dynamics of coastal Antarctic phytoplankton were
documented for a three month period as part of the Palmer Long Term Ecological
Research Project (PAL-LTER).  During the 1991-1992 summer season the mixed
layer depth shallowed, thus allowing the confined phytoplankton communities to
photoacclimate to the relatively stable in situ light levels.  Low light
photoadaptation within the subsequent diatom bloom was characterized by
increases in photosynthetic quantum yields and phytoplankton absorption
coefficients.  These photoadaptive changes occurred on the time scale of one
week and corresponded to high community growth rates (ca 1.4 div day-1) which,
in turn, resulted in high algal biomass (29.3 mg chlorophyll a m-3).
Increasing biomass levels shallowed the depth of the 1% light level from 60 m
prior to the bloom to 10 m during the bloom and coincided with a ten-fold
increase in the radiation utilization efficiency (e) of phytoplankton.  The
large and rapid changes in e illustrate the significant impact phytoplankton
can have on optical properties of coastal Antarctic waters with consequences
for the bio-optical modeling of in situ primary productivity.