Temperature Increase — An Uncertain Stimulant of Algal Growth and Primary Production in Fresh Waters

Abstract

Temperature profoundly influences the occurrence and organic production of algae in inland waters. Correlations deduced from seasonality of species are limited by numerous interactions. The kinetics of growth and photosynthesis are more unequivocal, although light and nutrient conditions affect rate-response to temperature, with reduced sensitivity at low irradiance. Specific growth rates, species-characteristic, have rarely been measured systematically with numerous common species and short intervals over an extended range of temperature.Different bases of quantitative analysis are cited; they include cardinal points, neo-Blackman behaviour, and the van't Hoff (Q10), Arrhenius (degrees K) and Bğlehrádek (with ‘biological zero’) formulations. Temperature-limits of specific growth rate are widely found, and variable with species, outside the 10–20 °C range. Low-temperature stenothermy is apparently uncommon, and high temperature (35 °C) species and strains are known. Maximum rates fall below an upper limiting envelope. In nature, species are only rarely most abundant at their optima for specific growth rate. Differences of temperature have indirect effects on algal distribution in a stratified water-column. Geographical distributions partly relate to temperature, although experimental elucidation is rare; there is indirect influence through ice-cover and altitude. Some prediction of rate-limitation is possible, both with latitude and globally.