INTRASPECIFIC VARIATION OF ALKENONE BIOSYNTHESIS IN GEPHYROCAPSA OCEANICA
Hanno Kinkel(1), Christine Klaas(2) & Ian Probert(3)
1 Netherlands Institute for Sea Research, Den Burg, Texel, The Netherlands
2 Geological Institute, Swiss Federal Institute of Technology, Zürich, Switzerland
3 Laboratoire de Biologie et Biotechnologie Marines, Universite de Caen, France
We analyzed the long-chain alkenone composition in six different strains of the coccolithophorid Gephyrocapsa oceanica from different regions of the world ocean. This study was carried out to test wether the temperaure calibrations based on core top sediments and cultures of Emiliania huxleyi can be applied to other alkenone producing coccolithophores, that dominate the fossil assemblages in sediments older than the last glacial period and therefore are considered as the main contributors to the alkenone saturation index ().
Previous studies and calibrations of G. oceanica showed significant differences in the index, mainly at temperatures below 20C, and were attributed to the limited occurrence of G. oceanica to tropical water masses. The investigated strains were isolated from such different places as the warm oligotrophic Gulf Stream, the cold nutrient rich North East Atlantic, and the Mediterranean. Their growth rate clearly reflect intraspecific variability, whereas alkenone biosynthesis does not. There is still considerable deviation from the generally accepted temperature realtionship, albeit it is smaller than previously reported. Furthermore we tested the influence of different growth phases on alkenone biosynthesis, and conclude that they may have no influence on the ratios at all.
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