Effects of biosynthesis and physiology on relative abundances and isotopic compositions of alkenones

TitleEffects of biosynthesis and physiology on relative abundances and isotopic compositions of alkenones
Publication TypeJournal Article
Year of Publication2001
AuthorsGonzalez, EL, Riebesell, U, Hayes, JM, Laws, EA
JournalGeochemistry Geophysics Geosystems
IssueWorking Group Report, Workshop on Alkenone-Based Paleoceanographic Indicators, 2000GC000052
Paginationart. no.-2000GC000052
Date PublishedJan 29
ISBN Number1525-2027
Keywordsalgae, alkenones, anhydrase, biogeochemical processes, biosynthesis, calcification, carbon-13, emiliania-huxleyi prymnesiophyceae, fractionation, Haptophytes, inorganic carbon utilization, instruments and techniques, isoprenoid biosynthesis, marine diatom, paleoceanography, photosynthesis, physiology, phytoplankton, sea surface temperature

The number of double bonds in long-chain, unsaturated ketones (alkenones) produced by some members of the Haptophyceae is correlated with the ambient temperature at the time of synthesis. For these same organisms the depletion of carbon-13 in biosynthetic products relative to dissolved inorganic carbon is related directly to the specific growth rate and inversely to the concentration of dissolved carbon dioxide. This report summarizes issues relating to the physiology, metabolism, and biochemistry of alkenone producers and how they affect the abundances and isotopic compositions of alkenones. These considerations show that an understanding of cellular responses to parameters governing uptake of inorganic carbon (C-i), isotopic fractionation, growth under diverse nutrient conditions, and genetic variability, both in the field and in culture, is necessary for developing a conceptual understanding of the biological significance of the epsilonp and U-37(K') indices. Emiliana huxleyi is the best known alkenone producer and can serve as a model organism for these studies. This report identifies knowledge gaps and appropriate objectives for both field- and laboratory-based research.