Predicting primary productivity in Westhampton Lake, Richmond, Virginia.

Several predictive photosynthetic models were tested using light, temperature, nutrient, chlorophyll, and primary productivity data collected from Westhampton Lake, Richmond, Virginia from February-September, 1972. A simple linear model, the Kendall rank correlation coefficient, was used to relate photosynthesis to individual meteorological, physical, chemical, and biological factors. iii Of the parameters measured, only the daily maximum photosynthetic efficiency ((P/chl) max ) was significantly correlated with photosynthesis. Five multiple factor (non-linear) models were tested. In the best fitting model, primary productivity was a function of the maximum observed ratio of photosynthesis/chlorophyll concentration, light intensity, temperature, nutrient concentrations, and chlorophyll concentration. The Pearson (r) correlation coefficient between predicted and observed values of photosynthesis for this model was .58, indicating that only 34% of the variability between predicted and observed values was accounted for by the model