Factors Affecting the Relation Between Phosphorus and Chlorophyll a in Midwestern Reservoirs

Publisher Website
Google Scholar
Abstract
The mean chlorophyll a [C] (mg/m3) yield per unit of total P (mg/m3) (P-C relation) in 96 Midwest reservoirs and the variance about this yield was similar to relations for natural lakes reported in the literature. The remaining error term for this relation could not be reduced by adding variables for N, zooplankton abundance or hydrologic flushing rate. In reservoirs with ratios of total N to total P of less than 10, N accounted for the same amount of variance in chlorophyll a as did P. Using partial regression path analysis, it was found that when the concentration of P was held constant, increasing the concentration of inorganic suspended solids (mg/l) significantly decreased chlorophyll a. The following multivariate equation was developed to account for the effect of inorganic solids on the P-C relation: .**GRAPHIC**. This equation accounted for 7% more variance than the univariate equation and the 95% predictive confidence interval, at an average P concentration, was reduced by 10%. This equation should be useful for predicting chlorophyll a in lakes with inorganic turbidities. When Secchi transparency data were regressed on both chlorophyll a and inorganic suspended solids, they accounted for 42% more variance in transparency than did chlorophyll a.
Keywords