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Project Progress

During this period John Marshall’s group has been examining and developing models of the oxygen cycle in the past and present oceans. In an earlier publication from this project, they demonstrated how it is difficult to achieve a widespread, sustained anoxia in models of the Late Permian Ocean. This has resulted in a dialog with a group at Pennsylvania State University on the representation of the oxygen cycle in ocean models. Marshall’s group has used a model of the modern ocean circulation and biogeochemistry to explore the implications of the simplified parameterizations that are under scrutiny. They find that allowing negative oxygen concentrations is misleading, though it might be interpreted as “total oxidant”, since it leads to very large and erroneous regions of anoxia in modern ocean simulations. A manuscript is in preparation concerning these results.

More detailed representations of oceanic nutrient and oxygen cycles are necessary and we have continued to develop such representations in the context of an atmosphere-ocean box model (Follows, in collaboration with Paul Falkowski at Rutgers).

Team member Douglas Erwin continued his research on the Permo-Triassic extinction. Planned field work in South China to acquire samples for a blind test of the suggested impact at the Permo-Triassic boundary was delayed by the outbreak of SARS, but is now scheduled for October 2003. Also a detailed database of species level fossil occurrences of Permian and Triassic gastropods is nearing completion for a planned analysis of extinction and recovery patterns. Erwin also continues to develop models of post-extinction biotic recovery and has nearly completed a book on the extinction for the general public (expected Sept. 2003).