Publication Date



Open access

Embargo Period


Degree Type


Degree Name

Doctor of Philosophy (PHD)


Marine Geology and Geophysics (Marine)

Date of Defense


First Committee Member

Peter K. Swart

Second Committee Member

Mark A. Altabet

Third Committee Member

Ali Pourmand

Fourth Committee Member

Gregor P. Eberli

Fifth Committee Member

Andrew C. Baker

Sixth Committee Member

Chris Langdon


This work addresses the threats of nitrogen loading to coral reefs and encompasses many unanswered questions on the topic of dissolved inorganic (DIN) utilization by Scleractinian corals and their endosymbiotic algae. Experimental efforts were made to understand the conditions under which NO3- or NH4+ leads to declines in calcification and identify other physiological changes in the coral-algal symbiosis which may accompany such growth declines. The synergistic influences of NH4+ and CO2 were investigated in order to gain insight on the potential influences of elevated DIN on corals in a high CO2 world. The study of NO3- and NH4+ uptake and impacts on corals hosting two different endosymbiont clades of Symbiodinium was carried out to predict how nutrient enrichments may influence corals which host more thermally tolerant symbiont communities. Finally, in light of the importance of managing nitrogen loading to reefs, the validity of the use of d15N in coral tissue as a nutrient source indicator was investigated through direct measurements of the 15N fractionation associated with NO3- and NH4+ uptake.


coral; symbiosis; nitrogen; stable isotope; fractionation; calcification