Modern Environments and Calibration Studies

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Map of core sites for WHOI benthic foraminiferal field calibrations.


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Multicorer is gently lowered into the sediment to collect undisturbed sediment from the sediment-water interface. The chemistry of foramininera sampled live in multi-core tops are calibrated against the modern overlying bottom water chemistry (Patrick Rowe, WHOI).


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A filled multicorer tube. Each multicorer has eight tubes. Several core-tops will be used for calibration to modern environments. Other multi-cores will be archived for the reconstruction of recent climate change, including climate during and since the Little Ice Age. (Photo: James Saenz, WHOI)


Calibration studies of benthic foraminiferal shell composition


The isotopic and elemental composition of the calcium carbonate shells of fossil benthic foraminifera are widely used to estimate deep-ocean chemistry and temperature at the time of calcification, but these estimates are only as good as our understanding of the controls on foraminiferal shell chemistry. Global field calibrations, based on core-top specimens collected along environmental gradients, form the foundation of most benthic foraminiferal paleoenvironmental proxies. To complement ongoing field studies, we are developing laboratory culturing methods to isolate and manipulate individual environmental factors that influence benthic foraminiferal shell composition.

People working on benthic foraminiferal calibrations at WHOI:




Calibration studies of living corals in their natural environment

Behind many coral-based paleoclimate records is an extensive calibration study designed to establish the relationship between skeletal composition and known (recorded) environmental variables such as temperature and salinity. Often, temperature loggers are attached to the living coral colony so that we know exactly what temperatures the coral experienced over a certain period of growth. In addition, we use Alizarin Red S, a pink CaCO3 stain, to place visible markers within the skeleton. Later, when the coral is sampled, the location of those stainlines tell us about rate and seasonality of skeletal growth.  Our current field sites include Bermuda and St Croix, USVI. We are also working on corals from the Great Barrier Reef, Mocambique and Sodwana Bay (southern Indian Ocean), Barbados, Bahamas, Tahiti, North Carolina and Woods Hole, Massachusetts!

People working on coral calibration studies at WHOI:

Anne Cohen

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Brain coral with three stainlines introduced
to the living colony over a period of one year.
(Anne Cohen)




 

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Last updated February 3, 2009
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