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Articles

Photosynthesis and Photorespiration in Algae ¹

^a Department of Biology, Queen's University, Kingston, Ontario K7L 3N6

The CO₂ exchange of several species of fresh water and marine algae was measured in the laboratory to determine whether photorespiration occurs in these organisms. The algae were positioned as thin layers on filter paper and the CO₂ exchange determined in an open gas exchange system. In either 21 or 1% O₂ there was little difference between ¹⁴CO₂ and ¹²CO₂ uptake. Apparent photosynthesis was the same in 2, 21, or 50% O₂. The compensation points of all algae were less than 10 µl 1^–1. CO₂ or ¹⁴CO₂ evolution into CO₂-free air in the light was always less than the corresponding evolution in darkness. These observations are inconsistent with the proposal that photorespiration exists in these algae.

³ Present address: Department of Zoology, Ohio State University, Columbus, Ohio.

¹ Supported in part by the National Research Council of Canada and Environment Canada, Fisheries and Marine Service.