My research investigates the relationship between changing ocean chemistry and the evolution of calcifying marine organisms. I am interested in all forms of biogenically-produced CaCO3, from coral aragonite to coccolithophorid calcite. Ongoing projects include investigating how long-term fluctuations in the Mg/Ca ratio of seawater influenced the form of CaCO3 (low-Mg calcite, high-Mg calcite, or aragonite) predominantly secreted by calcifying organisms throughout the geologic past. I am currently collaborating with Anne Cohen and Dan McCorkle to investigate how predicted elevations in atmospheric CO2 will influence calcifying organisms’ ability to build shells and skeletons in the future.
My approach constitutes a new field of research: Experimental Paleobiology. By subjecting modern organisms to predicted-future or inferred-ancient conditions, I am able to estimate how organisms respond to changes in the composition of seawater.These experiments identify the selective forces that will influence, or have influenced, the evolution of calcifying marine organisms in the near future or throughout the deep geologic past.My experimental approach is augmented through direct comparison with fossil organisms that actually formed shells and skeletons under the conditions that the experiments are seeking to replicate.
I employ multiple tools in the characterization of the morphology, chemistry, and mineralogy of biocalcified structures, including electron microscopy, atomic force microscopy, x-ray diffraction, element and isotope mass spectrometry, Raman spectroscopy, energy/wave dispersive spectroscopy, and ion microprobe. Recent advances in these technologies have shed new light on the microscale responses of organisms to changing seawater chemistry.While these changes occur primarily over small spatial scales, their evolutionary and ecological implications are proving large.