Three marine phytoplankton species (Skeletonema costatum, Olisthodiscus luteus andGonyaulax tamarensis) were grown in batch cultures at 15°C and a 14:10 L:D cycle at irradiance levels ranging from 5 to 450 μEinst m-2 s-1. At each irradiance, during exponential growth, concurrent measurements were made of cell division, carbon-specific growth rate, photosynthetic performance (both O2 and POC production), dark respiration, and cellular composition in terms of C, N and chlorophyll a. The results indicate that the three species were similar with respect to chemical composition, C:N (atomic) = 6.9 ± 0.4, photo-synthetic quotient, 1.43 ± 0.09, and photosynthetic efficiency, 2.3 ±0.1 × 10-3 μmol O2 (μg Chl a)-1 h-1 (μEinst m-2 s-1)-1. Differences in maximum growth rate varied as the -0.24 power of cell carbon. Differences in growth efficiency, were best explained by a power function of Chl a:C at μ = 0. Compensation intensities, ranged from 1.1 μEinst m-2 s-1 for S. costatum to 35 forG. tamarensis and were found to be a linear function of the maintenance respiration rate. The results indicate that interspecific differences in the μ-I relationship can be adequately explained in terms of just three parameters: cell carbon at maximum growth rate, the C:Chl a ratio (at the limit as growth approaches zero) and the respiration rate at zero growth rate. A light-limited algal growth model based on these results gave an excellent fit to the experimental μ-I curves and explained 97% of the observed interspecific variability.
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Aquatic Science