TITLE:     Mesoscale effects of ozone depletion on Antarctic phytoplankton
           primary production

AUTHORS:   NP Boucher, BB Prezelin and RC Smith

MEETING:   American Society of Limnology & Oceanography (ASLO) 1995 Meeting

PLACE:     University of Nevada, Reno

DATE:      11-15 June 1995


ABSTRACT:  Predictions of UV-dependent primary production rates in
natural phytoplankton communities require knowledge of an in situ
biological weighting function (Boucher and Prezelin, 1994).  The
approach is straightforward, providing certain other in situ
parameters are available on time and space scales of natural
variability.  First, knowledge of primary production in the absence of
UV stress must be known.  In our case, we used data collected over a
wide area (200 x 140 km2) west of the Antarctic Peninsula during the
November 1991 Long-Term Ecological Research (LTER) expedition.
Primary production was determined with high horizontal and vertical
resolution and on time scales less than one day from measurements of
phytoplankton P-I characteristics and incident photosynthetically
available radiation.  Next, knowledge of the UV fluence rate on time
and space scales matching primary production is required.  With the
increase of UV monitoring networks, such information is becoming
increasingly available.  In our case, we determined the incident UV
radiation from the combined knowledge of modeled clear sky radiation
and cloud coverage estimates.  We will present the horizontal and
vertical distribution of phytoplankton primary production, biomass and
major taxonomic markers over the LTER grid.  Using the inhibition
spectral model, we will then show the mesoscale losses of primary
production due to ambient UVR as well as enhanced levels of UV-B
radiation resulting from the 1991 seasonal ozone hole and discuss the
factors affecting their magnitude.