USGS Scientist Receives Best Student Poster Award at GSA 2008 Meeting
Paul Knorr, a graduate student in the Student Career Experience Program (SCEP) and geologist with the U.S. Geological Survey (USGS), received Best Student Poster Award from the Geological Society of America (GSA) on October 6, 2008. The Sedimentary Geology Division of GSA presented the award. Knorr's poster, "Effects of Increased pCO2 on Aragonite Crystal Morphology in Halimeda spp.," was coauthored by his USGS supervisor and co-advisor Lisa Robbins and University of South Florida advisor Peter Harries. This research highlighted some of Knorr's dissertation work on a species of the calcifying green alga Halimeda—an important producer of carbonate sediment in tropical, shallow-water, carbonate settings—and the alga's reaction to differing levels of CO2.
With higher levels of atmospheric CO2 being absorbed by the world oceans, there have been decreases in the pH and calcium-carbonate-saturation state of seawater. Understanding how organisms will respond to decreasing pH in seawater is a major research aspect for understanding global change. The main goal of the experiment was to determine how the alga Halimeda responds to lower pH levels associated with rising CO2. It is believed that continued decreases in pH will affect the rate and biogeochemical processes of calcification and carbonate-sediment production. (For example, see "Coral-Reef Builders Vulnerable to Ocean Acidification" in Sound Waves, March 2008.)
Using an automatic CO2-injector system, Knorr was able to regulate the amount of CO2 in an aquarium containing two species of Halimeda. The AquaController 3 controller/monitor (AC3) was programmed to keep the pH level at 7.5. Once sizeable specimens had been grown, the aragonite crystals within the algae were analyzed under a scanning electron microscope (SEM).
As presented in the award-winning poster, Knorr observed that the Halimeda opuntia grown in pH 7.5 water showed crystal growth about 55 percent smaller than normal, and Halimeda tuna showed crystals 19 percent smaller than those in the same species grown at pH 8.1, the current global average pH of ocean water. These data confirm the original hypothesis that lower pH levels will alter the carbonate production in these organisms. This research was initiated because of crystal trends seen in archived samples. Different species of Halimeda from the 1960s to the present also show trends of decreased crystal widths and increased abundance, as reported by Robbins, Knorr, and Pamela Hallock (University of South Florida) in a paper titled "Response of Halimeda to Ocean Acidification: Field and Laboratory Evidence," which will be published in the journal Biogeosciences Discussions.
Currently a doctoral student, Knorr followed an unusual path to the field of geology. While living in Munich, he took a geology class at the University of Maryland, Munich Campus, which included several field trips to both the Bavarian Kalkalpen (Northern Limestone Alps) and to Plitvice, Yugoslavia (now Croatia) that spurred his initial interest. He admits that, never having met a geologist, he didn't think geology was a practical choice for a career. Instead, he pursued a life in the U.S. Army.
Knorr, who grew up as an Army brat, spent 4 years as an infantry machine gunner and radio operator. During his first 2-year post as a paratrooper with the 82nd Airborne Division, he parachuted into Panama for Operation Just Cause. After another 18 months near the South Korean Demilitarized Zone, he left the Army to finish a degree in geology at the University of Florida. After college, Knorr, who was commissioned through ROTC, continued a career in the military and was stationed as an Army Lieutenant with the U.S. Army Corps of Engineers in Fort Lewis, Washington. There he applied the cartographic and topographic knowledge he had learned in his geology studies and at a Defense Mapping Agency (now the National Geospatial-Intelligence Agency) officer's course, but still believed his interests in geology were simply a side hobby.
After spending another 3 years in combat engineer units working with explosives and mines, Knorr decided that geology could be a more practical, happy, and perhaps safer career choice. He worked as a hydrogeologist for an environmental consultant for several years before attending the University of South Florida, where he received a Master's degree in geology. He is now working with Robbins and Harries on a doctoral dissertation focused on ocean acidification.
Knorr's general interest lies in understanding global change and how the Earth has responded to changes over geologic time. Specifically, he is interested in contributing to understanding ocean acidification, realizing that this phenomenon may have immediate and near-term effects on environmental change and the Florida ecosystem as a whole.
So what's next in Knorr's investigation of pH and CO2 levels? In an interview at the lab where the research was conducted, Knorr stated that the next steps would include looking at the effects of lower pH levels on different types of carbonate-producing organisms and sediments—specifically benthic foraminifera—and measuring how both are affected by ocean acidification.
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USGS Scientist Receives Best Student Poster Award