A researcher at the University of California at Davis proposes to collect living planktonic foraminifera and culture collected individuals using procedures established during prior funding periods. Once the foraminifera has calcified its shell under controlled conditions, the shells and culture water sample will be collected for geochemical analysis. These shells and water samples will be used to complete on-going geochemical experiments, conduct calibration experiments with new proxies (e.g., Li/Ca, Zn/Ca, 7Li, U/Ca), study the mechanisms of planktonic foraminifera calcification and shell geochemical variability that occurs during shell calcification and explore new geochemical relationships (i.e., the impact of different seawater Mg and Ca concentrations on shell geochemistry) and proxies using living planktonic foraminifera. The information gathered from this research will calibrate new and existing geochemical proxies with a level of confidence that cannot be obtained on planktonic species when using alternative approaches, such as sediment trap or core-top studies. This work will provide an unparalleled opportunity to gain insight into the processes of biomineralization and geochemical variation at the microscale, and provide a data set that can be used to understand the impact of changing seawater chemistry on foraminifera shell geochemistry. This will allow researchers to better interpret data from the fossil record.
As regards broader impacts, this study will ensure that a group of graduate students and post-docs from various institutions be trained by the PI and other experts in the field on the procedures for collecting and culturing these planktonic organisms, thereby ensuring that these techniques are passed on to the next generation of scientists. Undergraduate students will be involved in the field component of this research.
Planktonic foraminifera are a group of single celled marine organisms that live in the shallow depths of the ocean. These tiny organisms make a calcium carbonate shell and when they complete their 2-4 week long lifecycle, the shells sink to the the bottom of the ocean and become part of the fossil record. Millions of years of accumulation have left a rich fossil record for study. Locked within the microchemistry of these tiny (<1 mm) shells is a record of environmental conditions that existed when the organism was alive. The NSF has funded the planktonic foraminifera culturing project to calibrate the affect of different environmental and biological parameters on foraminifera shell geochemistry. Scuba divers collect living foraminifera by hand from oceanic surface waters and grow them in the laboratory under very controlled conditions. Experiments determine the relationship between changing environmental conditions such as temperature, salinity, pH, light levels or nutrients and the microchemical constituents of the shell, such as the stable isotopes of carbon, oxygen and boron, or elemental impurities such as Mg, U, Zn, Sr, Ba. We also explore the fundamental processes of biomineralization (how organisms make their shells) and symbiosis (the relationship between symbiotic dinoflagellates and host foraminifera). The results of this long-term project provides the geochemical calibrations needed to interpret the environmental information locked within million year old fossil foraminifera shells from deep sea sediment cores. Equipped with these laboratory derived calibrations, scientists can unravel the mechanisms of natural climate and ocean circulation change throughout Earth history. The images included with this summary are micrographs of living foraminifera from the culture project. The reader is encouraged to watch our documentary videos on the foraminifera culturing project: www.youtube.com/watch?v=xfZ_9UWcAB8 and www.youtube.com/watch?v=6MakjP6MkdE
