Influence of Free CO₂ on Q₁₀ for Chlorella Vulgaris

The effect of temperature on microbial growth rates is frequently expressed in terms of Q₁₀ values in which Q₁₀ equals rate at (T + 10)°C divided by rate at T°C. Considerable data exist suggesting that for algal growth described by the Monod equation, the maximum growth rate varies with temperature. To clarify the relationship between the limiting nutrient concentration and the temperature effect, the specific growth rate of the alga Chlorella vulgaris was determined at three temperatures over a range of free CO₂ levels with all other nutrients being provided in excess amounts and light being held constant. The resulting data using a modified Arrhenius equation to describe algal growth as a function of temperature under carbon limiting conditions were evaluated. The Q₁₀ values frequently found in laboratory determinations may be inapplicable under field conditions with natural waters. For biological modeling in natural waters, an equation is presented to describe the influence of the temperature on organism growth rates.