Award 1829093, “Collaborative Research: Deglacial and Holocene Environmental Change in California's Headwaters: Insights from High-Resolution Sedimentary Records from Mono Lake” sought to investigate the major controls on hydroclimate in the Sierra Nevada region of California at the Pleistocene-Holocene transition, train students, and conduct outreach to stakeholders working in the region. Snowmelt from the Sierra Nevada is crucial for California’s water supply, which provides a pillar of the state’s economy and the health and well-being of its vast population. Two long sediment cores were extracted from Mono Lake, one of America’s oldest and most iconic lake basins, which sits in a tectonic depression (the Mono Basin) on the eastern side of the Sierra Nevada.  Core sediments were investigated using multiple biological proxies, high-resolution geochemical sampling (scanning μXRF) and novel thin section analysis, to constrain patterns and processes of deposition with sufficient detail to support interpretations of environmental change. The project developed highly detailed stratigraphic and geochronological information for both cores, using radiocarbon applied to plant macrofossils, charcoal, and pollen purified by flow cytometry, and via development of the tephra chronology database for this region.  Together, the cores span the last ~16,000 years, and record both shallow and deep-water information on past climate and ecosystem dynamics; these data provide a rare opportunity for comparison with well-dated paleoshorelines that form rings around the extant lake.  The deepwater core was a focal point for paleolimnological and paleoecological study; pollen, spores, charcoal, diatoms, and ostracod microfossils were successfully separated from the sediments, identified to the species level using microscopy, and enumerated using statistical tools.  These data illustrate how both the terrestrial and aquatic ecosystems shifted in response to changes in temperature and precipitation in the Late Quaternary, and provided evidence for a connection between climate variability at high latitude (e.g., the North Atlantic) and ecosystem changes in the Mono Basin.  Ongoing research on ostracod shell geochemistry, bulk sediment chemistry, and biomarkers show promise for refining our understanding of paleohydrology and quantifying temperature and precipitation changes.  The project has supported two doctoral students, one M.S. student, and several undergraduate researchers. Further, project personnel have built a lasting connection with the non-profit Mono Lake Committee that is working to protect and restore the Mono Lake ecosystem.  Project sediment cores are preserved at the Continental Scientific Drilling Facility and will serve as a publicly accessible archive of environmental information that can be leveraged in future research.       

Last Modified: 11/06/2023
Modified by: Michael Mcglue