Hobart

Seminar Abstract

Tuesday 31 March 2009, 11.30am (Tas time)
CSIRO Auditorium, Hobart

Jorijntje Henderiks
Department of Geology and Geochemistry
Stockholm University
Sweden

Coccolithophore Evolution and Adaptation to Climate Change

Rising ocean temperatures and lowering of ocean pH may disrupt marine productivity and calcification by coccolithophores, a prominent group of unicellular marine algae, affecting natural biosphere-climate feedbacks. A better understanding of both the mechanisms and the rates of climatic adaptation by coccolithophores is critical for predicting future impacts of climate change. I will discuss how contrasts in the physiology and biogeography of modern coccolithophores could relate to different climatic adaptation strategies of their Cenozoic ancestors. On short time scales, experimental results highlight species-specific sensitivities to changing ocean carbonate chemistry, which is consistent with differences in cell size of the investigated taxa and likely related to intracellular pH control. On geological time-scales, coccolithophores appear to have adapted to a long-term decrease in atmospheric carbon dioxide pCO₂ and cooling ocean temperatures by decreasing their coccolith and cell size. A macroevolutionary size decrease within the Reticulofenestra lineage (the ancestry of today’s most prolific bloomer Emiliania huxleyi) appears to primarily reflect a physiological adaptation to CO₂ limitation. In contrast, macroevolutionary size variability within the Coccolithus lineage (the ancestry of Coccolithus pelagicus and C. braarudii), while influenced by long-term trends in ocean temperature, is not affected by changes in CO₂. Improved understanding of such heterogeneity within ecosystem functional groups, including taxon-specific climatic adaptation strategies, will be of fundamental importance to the assessment of future climate change impact and mitigation.

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Location:
CSIRO = Marine Laboratories Auditorium, Castray Esplanade, Hobart

For further information, or to schedule a seminar, contact:
To schedule a seminar, contact:
Clothilde Langlais, (Oceanographic seminars) CSIRO Marine and Atmospheric Research (03) 6232 5399
Natalie Kelly, (Biology/Modelling seminars) CSIRO Marine and Atmospheric Research 0438 452 483
Jillian Enraght-Moony, (seminar administrator) CSIRO Marine and Atmospheric Research (03) 6232 5320
Communications Manager, Antarctic Climate and Ecosystems CRC (03) 6226 2265
Margaret Hazelwood, Institute of Antarctic and Southern Ocean Studies (IASOS) University of Tasmania (03) 6226 2971

Last updated 21/07/09