Predicting epilimnetic phosphorus concentrations using an improved diatom-based transfer function and its application to lake eutrophication management

A diatom transfer function based on data from 152 lakes in northwest Europe is derived using the technique of weighted-averaging partial least squares (WAPLS) and applied to Lake Sobygard, a shallow, hypertrophic Danish lake, to infer past changes in epilimnetic total phosphorus (TP) concentrations since the 1930s. The results show that the two-component WAPLS model has low prediction errors (RMSEP = 0.21 log(10) TP units) and is applicable to lakes distributed throughout northwest Europe, covering a TP range 10-1000 mu g TP L(-1). The example shows how the method can provide an estimate of baseline conditions and rates of enrichment, allowing managers to set realistic targets for lake restoration.