An energy balance for algal populations in light-limiting conditions

Summary

Growth of Scenedesmus protuberans was studied in light-limited continuous cultures, with a diurnal light-dark cycle of 16 and 8 hours respectively at 20 °C.

All incident light energy was absorbed when the cultures were in steady state. Both cultures receiving 30,000 and 13,000 J day⁻¹1⁻¹ were used. Production was measured, from daily outputs of the cultures, as biovolume, with a Coulter Counter, as dry weight and as heat of combustion, with a Phillipson Microbomb Calorimeter. An energy balance was derived, considering the light energy to be used for growth and maintenance of the algae. Maintenance energy was extrapolated from production data at various growth rates. It was found that the maintenance rate constant, in the given conditions, was 0.20 day⁻¹.