Diel patterns of photosynthate biosynthesis by phytoplankton in permanently ice-covered Antarctic lakes under continuous sunlight

• Published in: Journal of Plankton Research
• Main Authors: Priscu, J.C., Priscu, L.R., Howard-Williams, C., Vincent, W.F.
• Format: Text
• Language: English
• Published: Oxford University Press 1988
• Subjects: Articles; Antarctic; Vanda; Fryxell; Lake Fryxell; Lake Vanda; Antarc*
• Online Access: http://plankt.oxfordjournals.org/cgi/content/short/10/3/333; https://doi.org/10.1093/plankt/10.3.333

Diel patterns of photosynthate biosynthesis by Antarctic freshwater phytoplankton growing under the variable but continuous sunlight of summer were found to be similar in many respects to those reported from other aquatic environments where light/dark periods alternate. Lipid synthesis by freshwater phytoplankton in Lakes Vanda and Fryxell predominated during periods when solar radiation and photosynthesis were most intense; the inverse was generally true of the protein and polysaccharide fractions. The major photosynthetic end-products in both lakes were protein and polysaccharide, which together accounted for 60–81% of the total cellular carbon incorporation. Less than 4% of the carbon was incorporated into lipid in Lake Vanda; >12% appeared in the lipid fraction in Lake Fryxell. The Lake Fryxell populations showed evidence of photoinhibition of complete photosynthesis during ‘midday’ when irradiance was most intense. I k values, computed from the photosynthesis irradiance relationships in Lake Fryxell, corroborate other studies suggesting that the phytoplankton populations in permanently ice-capped Antarctic lakes are among the most shade-adapted yet reported.