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Daniel Dean Gray

Institution:University of Bremen
Room:MARUM II, room 1050
Phone:+49 421 218 - 65956
E-mail:[Bitte aktivieren Sie Javascript]
Other webpage(s):Dan's MARUM web page
Daniel Gray

PhD project:

Aerobic degradation of organic-walled dinoflagellate cysts

Organic matter (OM) derived from terrestrial and marine environments serve as key proxies for past climate and
environmental variability. Estimating OM stability and preservation in the geological record is thus an important step in quantifying the accuracy of climate reconstructions.

However, many of the climate proxies we use to estimate climate variability undergo significant chemical and
physical alteration as they settle onto the seafloor, and are incorporated into sediments. For example, high bottom water oxygen concentrations/exposure has been implicated in “enhanced” degradation/alteration of marine organic matter.

In my phD project, I will use the fossils of marine plankton; specifically dinoflagellate cysts to assess how varying oxygen exposure controls degradation in marine sediments. It has been shown, that dinoflagellate cysts have a species specific response to oxygen exposure - this means that the preferential concentration or loss of certain species tells us something about how fast or slowly degradation is taking place overall.

I will try to quantitatively estimate the degradation potential of a wide range of dinoflagellate species, through a series of experiments. These experiments look to track how dinoflagellate species assemblages change with varying exposure conditions, i.e. time (d -1 to yr -1 ), ambient oxygen concentration, and bacterial microhabitat. Using drilled sediment cores from the Mediterranean, I will then apply this insight and track historical changes in bottom water oxygen exposure, based on cyst assemblage composition.

Thesis committee:

PD. Dr Karin ZonneveldUniversity of Bremen
Dr Gerard VersteeghUniversity of Bremen
Dr Kara BogusUniversity of Texas A&M