Dr. David L. Dettman, Visiting Professor

Greetings! I am David Dettman, a Research Scientist in the Geosciences Department of the University of Arizona. I will be visiting for one year as a Guest Professor in the Center, until the end of July 2004.

My primary research area has been oxygen stable isotopes in ancient fresh-water systems. Using shells and other carbonates in non-marine settings I have worked on paleo-climate, seasonality, and paleo-elevation studies. My work in modern estuarine settings led to a study of paleo-salinities in the Gulf of California prior to major human modification of the Colorado River flow through Dam construction. I am currently working on a project that will quantify Colorado River flow amounts over the last 1000 years.

One of the research projects I would like to pursue while here at the Center is a study of salinity variation through time in Lakes Shinji and Nakaumi. Using dated materials from cores housed at the Center, I will look at the stable isotope chemistry of organic matter and carbonates to get a broad picture of salinity variation during most of the Holocene. An interesting addition to this study will be seasonal stable isotope data from the sub-division of growth bands in shells from the cores. This may give us information about the changes in the seasonal patterns of rainfall in this region.

I have recently become interested in the use of stable isotope chemistry in ecology and am involved in three studies of animal ecology in the Gulf of California. One examines the environmental requirements of the nearly extinct bivalve, Mulinia coloradoensis. The other two examine the importance of the Colorado River in the life-history of a porpoise endemic to this region, Phocena sinus, and of an endangered fish species, Totoaba macdonaldi.

I look forward to learning more about the use of stable isotopes in ecology while working with ecologists here at the Center.