TABLE 2.
Results of multiple regression analysis identifying the strongest (lowest predicted residual error sum of squares and highest adjusted R2) physicochemical or biological predictors for microcystins or geosmin over the study period (2013 to 2014)a
| DV | Model | y int | nvars | N | n | Adj. R2 | PRESS | Data |
|---|---|---|---|---|---|---|---|---|
| Microcystin | MC1/2 ∼ mcyE1/2 · 0.0007 | 0.27 | 1 | 10 | 18 | 0.84 | 0.13 | qPCR |
| Microcystin | MC1/3 ∼ pH1/3 · 4.2 + Cond−1 · 0.92 + PO4 · 4.3 + TP · 1.7 | −17.0 | 4 | 40 | 26 | 0.82 | 0.78 | Sonde + lab |
| Microcystin | MC1/3 ∼ Temp1/3 · −0.53 + Turb · 0.02 + DO · 0.07 + sin · −0.38 + cos · −0.87 | 0.90 | 4 | 40 | 36 | 0.47 | 1.7 | Sonde |
| Geosmin | log10(GEO) ∼ log10(geoA) · 0.76 | −1.79 | 1 | 10 | 31 | 0.71 | 10.9 | qPCR |
| Geosmin | GEO−1 ∼ DO · −0.11 + DP−1 · −0.01 + TP−1 · 0.04 + sin · 0.47 + cos · 0.29 | 1.20 | 4 | 40 | 28 | 0.51 | 1.2 | Sonde + lab |
| Geosmin | GEO−1 ∼ Temp · −0.04 + pH−1 · 10.6 + Cond−1 · 605.6 + sin · 0.10 + cos · −0.63 | −1.08 | 4 | 40 | 41 | 0.63 | 1.1 | Sonde |
DV, dependent variable; y int, y intercept; nvars, number of independent variables; N, minimum number of observations required (37); n, number of observations analyzed; PRESS, predicted residual sum of squares; Adj. R2, adjusted R2; Cond, specific conductance (microsiemens per meter); DO, dissolved oxygen (milligrams per liter); DP, dissolved phosphorus (milligrams per liter); geoA, qPCR result (geoA gene copies per milliliter); GEO, geosmin (nanograms per liter); MC, microcystin; mcyE, qPCR result (mcyE gene copies per milliliter); PO4, orthophosphate (milligrams per liter); Temp, temperature (degrees Centigrade); TP, total phosphorus (milligrams per liter); Turb, turbidity (formazin nephelometric units [FNU]).