Corals as recorders of ocean pH: is the boron isotope proxy influenced by seawater temperature and coral physiology?

Verena Schoepf
The Ohio State University, School of Earth Sciences Columbus, Ohio, USA
[email protected]

Reconstruction of paleoclimate is crucial in predicting the occurrence of petroleum source beds because the two most important factors associated with their occurrence, high organic productivity and preservation, are directly related to paleoclimate. The nutrient-rich, low-pH seawater of upwelling regions provide ideal settings for the deposition of petroleum source beds. As the boron isotopic ratio (δ¹¹B) of coral skeletons is a promising recorder of ocean pH in tropical coastal areas, this proxy can potentially be used to reconstruct and identify settings favorable to the deposition of petroleum source beds.

Although the boron isotope proxy has shown promising results in recording ocean pH, the influence of temperature and coral biology on skeletal δ¹¹B remains largely unknown, which is of great concern for reconstruction of paleoclimate. The goal of this research is to conduct controlled, replicated experiments where 2 coral species with different morphologies will be subjected to 2 temperature and 2 pH levels, while simultaneously monitoring their physiology. I will test the hypothesis that coral skeletal δ¹¹B is controlled by seawater pH, but not by either temperature or so-called vital effects. This will enable me to assess if coral δ¹¹B faithfully records ocean pH, thus potentially encouraging the wider use of this pH proxy and fostering our understanding of paleoclimate.

AAPG Search and Discovery Article #90157©2012 AAPG Foundation 2012 Grants-in-Aid Projects