Hiriart, V. P. University of Waterloo, vphiriar@scimail.uwaterloo.ca
Smith, R. P. University of Waterloo, rsmith@scimail.uwaterloo.ca
Greenberg, B. University of Waterloo, greenber@scimail.uwaterloo.ca
Charlton, M. National Water Research Institute, murray.charlton@cciw.ca

 
LAKE ERIE AND THE POTENTIAL CONSEQUENCES OF ENHANCED LEVELS OF ULTRAVIOLET RADIATION FOR PHYTOPLANKTON PRODUCTION
 
RECENT OBSERVATIONS OF DECREASING CONCENTRATIONS OF STRATOSPHERIC OZONE IN NORTHERN MID-LATITUDES HAVE HEIGHTENED CONCERNS ABOUT THE POTENTIAL IMPACTS OF ELEVATED ULTRAVIOLET RADIATION (UVR) ON TEMPERATE FRESHWATER ECOSYSTEMS. IN THIS STUDY, THE IMPACT OF UVR ON PHYTOPLANKTON PRIMARY PRODUCTION WAS INVESTIGATED IN LAKE ERIE IN 1997 AND 1998. CARBON INCORPORATION RATES WERE MEASURED IN LAKE WATER SAMPLES EXPOSED TO A VARIETY OF SPECTRAL RADIATION TREATMENTS FOR VARYING PERIODS OF TIME. THE KINETICS OF PHOTOINHIBITION WERE INVESTIGATED AND BIOLOGICAL WEIGHTING FUNCTIONS (BWF), WHICH QUANTIFY BIOLOGICAL EFFECTS OF UVR AS A FUNCTION OF WAVELENGTH, WERE DERIVED. THE INHIBITION OF PHOTOSYNTHESIS WAS NON-LINEARLY DEPENDENT ON WEIGHTED CUMULATIVE RADIATION EXPOSURE, RATHER THAN INSTANTANEOUS IRRADIANCE, SUGGESTING THAT REPAIR PROCESSES WERE SLOW COMPARED TO DAMAGE PROCESSES. THE BWF DERIVED IN THIS STUDY WILL BE COMPARED BETWEEN DATES TO ASSESS THE TEMPORAL VARIABILITY IN SENSITIVITY TO UVR, AND COMPARISONS WILL BE MADE BETWEEN THE FRESHWATER BWF FROM THIS STUDY AND PREVIOUSLY PUBLISHED BWF FOR MARINE PHYTOPLANKTON. BWF ARE PRACTICAL FORECASTING TOOLS AND WILL BE APPLIED HERE TO MODEL THE POTENTIAL IMPACTS OF OZONE DEPLETION AND ENHANCED WATER CLARITY ON WATER COLUMN PRIMARY PRODUCTION.
 
Day: Wednesday, Feb. 3
Time: 11:00 - 11:15am
Location: Sweeney Center
 
Code: CS65WE1100S