Using Q10:: Can growth rates increase linearly with temperature?

For autotrophic and heterotrophic protists, we reviewed growth rate versus temperature data (92 cases, 74 species, 36 studies), using non-linear curve-fitting methods to determine whether relationships were linear. Of the 92 cases, 67 contained sufficient data for analysis; 61 did not significantly differ from a linear response (mean slope: 0.064 +/- 0.005 d(-1)degreesC(-1)). Of the 25 cases that were not statistically analysed, 18 appeared linear. The mean slope of the 79 data sets considered to be linear was 0.07 +/- 0.005 (d(-1) degreesC(-1)). We suggest that growth rate usually responds linearly to temperature, the use of Q(10) may be inappropriate, and a Q(10) of 2 may arise due to this linear relationship and inappropriate experimental design.