SS4.05 Tribute to Thomas Frost
Date: Monday, June 10, 2002
Time: 3:00:00 PM
Location: Sidney
 
SandersonB, Northwest Fisheries Science Center, Seattle, USA, Beth.Sanderson@noaa.gov
 
INTER- AND INTRA-ANNUAL VARIABILITY IN LIGHT TRANSMISSION IN NORTHERN WISCONSIN LAKES OF DIFFERING TROPHIC STATUS
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I considered the extent to which chlorophyll and/or DOC could explain inter- and intra-annual fluctuations in light transmission in a set of oligotrophic, mesotrophic, and dystrophic lakes over an 11-year period. First, I quantify variation in light transmission as measured by Secchi depth and attenuation coefficient. Secchi depth was highly variable in oligotrophic lakes, but varied little in dystrophic lakes. In contrast, attenuation coefficients were markedly consistent in oligotrophic lakes, yet highly variable in dystrophic lakes. Patterns in the variability of two potential driving variables, algal biomass and dissolved organic carbon, were distinct among lake types. Among years, chlorophyll fluctuated in all lakes, whereas DOC was steady in oligotrophic lakes but varied in dystrophic lakes. In oligotrophic lakes, the correlation between Secchi depth and chlorophyll was consistently tight, indicating algal biomass drives much of the variation in light transmission. In contrast, changes in DOC were correlated with light transmission in only one lake. Combined, these results identify how long and short term variations in light transmission are related to dynamics in algal biomass and DOC in a range of lakes. SS 4-05 Tribute to Thomas Frost ORAL SANDERSON, B.L.