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The Effects of Dramatic Climate Change on Marine Planktonic Microbes: A History Lesson
Reference
Cermeņo, P. 2011. Marine planktonic microbes survived climatic instabilities in the past. Proceedings of the Royal Society B 279: 474-479.

Background
To emphasize the significance of the little critters, the author begins his paper on marine planktonic microbes by stating that "micro-organisms dominate terrestrial, aquatic and aerial ecosystems and largely rule our planet's life by playing pivotal roles in global biogeochemical cycles," citing the writings of Staley and Fuhrman (2002) and Falkowski et al. (2008), while declaring that as a result of these facts, "life on earth is microbe dependent."

What was done
Cermeņo used records of climatic variability and microfossil data covering the past 65 million years, which were obtained from the world's oceans, to "explore the linkage between the rate of climate change and the probability of extinction, origination and net diversification of marine planktonic diatoms and calcareous nannoplankton," analyzing the evolutionary dynamics of the two phytoplankton groups throughout the 65-million-year period of study and comparing the results with the climate change record.

What was learned
The Spanish researcher says his findings demonstrate that "the probability of extinction of microbial plankton species did not increase during periods of enhanced climatic instability over the past 65 million years." In fact, he says that this results show that "exceptional climatic contingencies, such as those occurring across the Late Palaeocene-Eocene and the Eocene-Oligocene boundary transitions, caused substantial morphological diversification."

What it means
In summing up his findings and their significance to the concerns of our day, Cermeņo concludes his analysis by stating that "to the extent that contemporaneous trends in climate change have analogies with the climates of the geological period analyzed here, my results suggest that these microbial plankton groups will persist in the future ocean, perhaps even expanding their ranges of morphological diversity."

These findings are obviously extremely good news, particularly in light of the fact, as Cermeņo states, that "life on earth is microbe dependent."

References
Falkowski, P.G., Fenchel, T. and DeLong, E.F. 2008. The microbial engines that drive Earth's biogeochemical cycles. Science 320: 1034-1039.

Staley, J.T. and Fuhrman, J.A. 2002. Microbial diversity. In: Mooney, H. and Canadell, J.G. (Eds.). Encyclopedia of Global Environmental Change. Wiley & Sons, Chichester, United Kingdom, pp. 421-425.

Reviewed 23 May 2012