Smith, Christopher Instructional Assistant Professor

My graduate research primarily revolved around using microscopic organisms called foraminifera as environmental indicators, using both microfossils and extant groups in the present day. Foraminifera are extraordinarily sensitive to environmental changes, which makes them a potentially valuable tool in a wide array of research avenues.

Under Dr. Susan Goldstein at the University of Georgia, my doctoral project involved the effect of heavy metals such as arsenic, cadmium, copper, nickel, and zinc on foraminifera. Because foraminifera are so sensitive to environmental shifts in everything from temperature to salinity to pH, it can be historically hard to ascertain the specific effects of heavy metals and other pollutants on foraminifera. Specifically, it is not known if there is a major difference in how these elements affect foraminifera. In addition, it is unclear whether different clades of foraminifera respond to heavy metal influence in the same fashion. The goal of this study was to enhance the utility of foraminifera as bioindicators by seeking answers to these questions so that potential bioindicator species might be confirmed. To do this, I used a technique pioneered by Dr. Goldstein and Dr. Elisabeth Alve that involves the harvesting of propagules. Propagules are juvenile foraminifera present in aquatic sediment. By sieving out everything except the smallest possible fraction, the propagules can be isolated and placed in conditions of the researcher's choosing. Sediment samples were taken from two different coastal sites: Sapelo Island, Georgia, and Little Duck Key, Florida. Using the propagule method, assemblages of foraminifera were grown in the laboratory from propagules in the sediment samples, with exposure to selected individual heavy metals. The metals had an overall negative effect on the population dynamics and shell chemistry of foraminifera. Zinc in particular seems to cause shell deformities in certain species at elevated concentrations. This research also used laser ablation ICP-MS to explore possible incorporation of the metals into the foraminiferal shell itself. Using facilities at Oregon State University, LA-ICP-MS revealed that the vast majority of foraminifera incorporated the surrounding heavy metals in the water into their tests. The amount of metal incorporated seemed to depend on the species and metal involved, revealing possible vital effects at work governing biochemical reactions between the foraminifera and the elements in the seawater. This doctoral project resulted in three professional papers, all three of which are published, with two in the Journal of Foraminiferal Research and one in Marine Micropaleontology.