RELATION OF ALGAL BIOVOLUME TO CHLOROPHYLL-A IN SELECTED LAKES AND WETLANDS IN THE NORTH CENTRAL UNITED-STATES

Algal chlorophyll a is commonly used as a surrogate for algal biomass. Data from three lakes in western Nebraska, five wetlands in north-central North Dakota, and two lakes in north-central Minnesota represented a range in algal biovolume of over four orders of magnitude and a range in chlorophyll a from less than 1 to 380 mg . m(-3). Analysis of these data revealed that there was a linear relation, log(10) algal biovolume = 5.99 + 0.09 chlorophyll a (r(2) = 0.72), for cases in which median values of chlorophyll a for open-water periods were less than 20 mg . m(-3). There was no linear relation in cases in which median chlorophyll a concentrations were larger than 20 mg . m(-3) for open-water periods, an occurrence found only in shallow prairies lakes and wetlands for years in which light penetration was the least.