How does rising atmospheric CO2 affect marine organisms?

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Palaeoclimate Histories May Need Some Adjustments
Reference
Darling, K.F., Wade, C.M., Stewart, I.A., Kroon, D., Dingle, R. and Leigh Brown, A.J.  2000.  Molecular evidence for genetic mixing of Arctic and Antarctic subpolar populations of planktonic foraminifers.  Nature 405, 43-47.

What was done
The authors examined the genetic variation in the small subunit ribosomal RNA gene of three morphospecies of planktonic foraminifera from Arctic and Antarctic subpolar waters.

What was learned
It was discovered that foraminiferal morphospecies can consist of a complex of genetic types.  Indeed, the authors found that each "species," as these entities have previously been denominated, was composed of three to five distinct genetic varieties that could possibly be classified as individual species themselves.

What it means
The morphological, chemical and stable-isotope differences associated with the calcitic shells of the three morphospecies studied by the authors are used extensively by palaeoceanographers for purposes of climate reconstruction, based on the assumption that each morphospecies represents a genetically continuous species with a single environmental/habitat preference.  However, as they now warn us, "if this is not the case - as indicated by this study and others - stable-isotope and geochemical analyses of planktonic foraminiferal shells, and census-based transfer-function techniques derived from such pooled data, must include significant noise, if not error."  Hence, as more is learned about the diversity of these biotic climate indicators, certain palaeoclimatic histories may have to be revised.


Reviewed 15 July 2000