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-cen tral North Dakota, and two lakes in north-central Minnesota represente d a range in algal biovolume of over four orders of magnitude and a ra nge in chlorophyll a from less than 1 to 380 mg . m(-3). Analysis of t hese data revealed that there was a linear relation, log(10) algal bio volume = 5.99 + 0.09 chlorophyll a (r(2) = 0.72), for cases in which m edian 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 chl orophyll a concentrations were larger than 20 mg . m(-3) for open-wate r periods, an occurrence found only in shallow prairies lakes and wetl ands for years in which light penetration was the least.