Light absorption and size scaling of light-limited metabolism in marine diatoms

Finkel, Zoe Vanessa

Limnol. Oceanogr., 46(1), 2001, 86-94 | DOI: 10.4319/lo.2001.46.1.0086

ABSTRACT: Previous studies have found that the size-scaling exponent of metabolic rates in unicellular algae often deviates from the exponent of -1/4 usually found for heterotrophs. This study confirms a significant linear relationship between log cell volume (mm3) and log intrinsic growth rate (h-1), carbon-normalized photosynthetic capacity and performance (h-1), and carbon-normalized respiratory rate (h-1) for eight marine centric diatoms under nutrient-saturated, light-limited conditions. The intrinsic growth rate and carbon-normalized respiratory rate have size-scaling exponents not significantly different from -1/4, whereas the carbon-specific photosynthetic rates deviate from -1/4. The size dependence of the optical absorption cross section (m2 mg chlorophyll a-1) due to the package effect provides a mechanistic model that explains the anomalous size scaling of the anabolic rates of unicellular phytoplankton.

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