ELT Collaborative Research: Perturbation of the Marine Food Web and Extinction During the Oceanic Anoxic Event at the Cenomanian/Turonian Boundary

ELT Collaborative Research: Perturbation of the Marine Food Web and

Extinction during the Oceanic Anoxic Event at the Cenomanian/Turonian

Boundary

by

Timothy Bralower, Penn State University, EAR-1338316

Bradley Sageman, Northwestern University, EAR-1338312

R. Mark Leckie, Univ. Massachusetts, Amherst, EAR-1338317

Julio Sepulveda, MIT, EAR-1338318

ABSTRACT

The expansion of oxygen-deficient waters, known as hypoxia, is occurring seasonally in places such as the Gulf of Mexico as a result of warming and pollution. Hypoxia can affect all marine organisms through the loss of habitat, changes in predator-prey dynamics, and availability of nutrients for primary production. Ocean acidification resulting from the input of anthropogenic CO2 is already impacting the ability of many organisms to grow shells. The geological record contains a series of natural experiments that allow us to address the biological response of the biota to ocean acidification and widespread oxygen deficiency.

The Cenomanian-Turonian boundary (94 million years ago in the middle of the Cretaceous Period), a time interval marked by mass extinction, was also characterized by global oxygen deficiency and likely ocean acidification. Thus, the Cenomanian-Turonian boundary is an excellent ancient model for the impact of anthropogenic activities on marine ecosystems. A superb opportunity exits to explore the impact of oxygen deficiency and ocean acidification during the Cenomanian-Turonian boundary in rock outcrops from the western and southern margins of the US Western Interior Seaway. In Utah, rocks contain original ammonite aragonite as well as remains of large marine reptiles. In Texas, British Petroleum has made available a unique core and exclusive access to outcrop sections. Back-hoeing of rock outcrops will unearth pristine fossil shells suitable for reconstruction of ancient environmental conditions using geological proxies, and coring will provide rocks that can be studied to determine changes that took place over centuries. The insight gained from the CTB can be applied to other intervals of biotic upheaval in Earth history and will help improve projections of the impacts of human activities, including hypoxia and ocean acidification, on modern ecosystems.