|CS36 Ultraviolet Radiation|
|Date: Friday, June 14, 2002|
|Time: 9:15:00 AM|
|Huggins, K, , Universite du Quebec a Trois-Rivieres, Trois-Rivieres, Canada, Kim_Huggins@uqtr.ca|
|Frenette, J, J, Universite du Quebec a Trois-Rivieres, Trois-Rivieres, Canada, Jean-Jacques_Frenette@uqtr.ca|
|Arts, M, T, National Water Research Institute, Burlington, Canada, Michael.Arts@EC.GC.CA|
|NUTRITIONAL QUALITY OF BIOFILMS IN LAKE SAINT-PIERRE AS A FUNCTION OF THE UNDERWATER LIGHT CLIMATE|
|Biofilm communities were sampled in two water masses situated in a fluvial lake located within the Saint-Lawrence River. One of the two water masses was characterized as having a lower concentration of chromophoric dissolved organic matter (CDOM) resulting in deeper UVR penetration. We designed specialized incubation devices for growing biofilms on artificial substrates in such highly hydrodynamic fluvial systems. The incubation devices allowed us to grow biofilms at fixed depths (despite seasonally changing water levels) and were resistant to currents and waves. The biofilms were allowed to develop in the two water masses under different light regimes: with UVR, no UVR, no UVB, or 90%, 70%, or 50% transmission of ambient solar radiation.
We will compare the nutritional quality (lipid content and stoichiometry) of biofilms growing in these two water masses in relation to the artificially manipulated UV and light fields (PAR). Enhanced UV-B as a result of ozone depletion is an issue of increasing concern. Our new incubation device will allows us to evaluate the effects of UV radiation on the nutritional quality and physiological competencies of riverine biofilms.