Using Chlorophyll Fluorescence to Determine the Fate of Photons Absorbed by Phytoplankton in the World's Oceans

• Published in: Annual review of marine science Vol. 14; no. 1; pp. 213 - 238
• Main Authors: Gorbunov, Maxim Y, Falkowski, Paul G
• Format: Journal Article
• Language: English
• Published: United States Annual Reviews 03-01-2022; Annual Reviews, Inc
• Subjects: Chlorophyll; Chlorophylls; Climate change; Energy budget; Energy conversion; Energy conversion efficiency; Fluorescence; fluorescence lifetime; Instruments; Measuring instruments; Nutrient cycles; Oceans; Oceans and Seas; Photochemistry; Photons; Photosynthesis; Phytoplankton; Solar energy; variable fluorescence; fluorescence lifetime; variable fluorescence; photosynthesis
• ISSN: 1941-1405; 1941-0611
• DOI: 10.1146/annurev-marine-032621-122346

Approximately 45% of the photosynthetically fixed carbon on Earth occurs in the oceans in phytoplankton, which account for less than 1% of the world's photosynthetic biomass. This amazing empirical observation implies a very high photosynthetic energy conversion efficiency, but how efficiently is the solar energy actually used? The photon energy budget of photosynthesis can be divided into three terms: the quantum yields of photochemistry, fluorescence, and heat. Measuring two of these three processes closes the energy budget. The development of ultrasensitive, seagoing chlorophyll variable fluorescence and picosecond fluorescence lifetime instruments has allowed independent closure on the first two terms. With this closure, we can understand how phytoplankton respond to nutrient supplies on timescales of hours to months and, over longer timescales, to changes in climate.