PRELIMINARY LATE QUATERNARY OSTRACODE STRATIGRAPHY AND PALEOECOLOGY FROM MONO LAKE (EASTERN SIERRA NEVADA)

In this contribution, we present a preliminary ostracode stratigraphy from Mono Lake (California). As a long-lived endorheic lake on the eastern side of the Sierra Nevada range, Mono Lake contains a proxy-rich sedimentary archive of hydroclimate and ecological change for a region of great importance to California’s water supply. Our ostracode record was developed from a relatively long sediment core collected in 2015 from Mono Lake’s western embayment in water ~18 m deep. The core chronology, which spans ~16.9-4.2 cal ka BP, was established using radiocarbon and correlation to well-dated tephras. Ostracodes are relatively well-preserved and abundant in the Late Pleistocene sediments, whereas taphonomic damage and faunal abundance decline after ~ 11.0 cal ka BP, perhaps driven by lower lake-level elevation and variable limnological conditions crossing the Pleistocene-Holocene transition. Preliminary analysis indicates the presence of adults and juveniles from seven different ostracode species: Limnocythere staplini, Limnocythere ceriotuberosa, Limnocythere sappaensis, Candona patzcuaro, Fabaeformiscandona caudata, Potamocypris sp., and Eucypris meadensis. The most common species in the record is L. ceriotuberosa, and as such will be the target of future shell chemistry (stable isotopes, trace elements). Ostracodes from the Family Candonidae are largely restricted to Pleistocene-aged sediments, possibly due to colder water temperatures and a deeper sub-littoral zone when lake-level elevations were higher. Changes to Mono Lake’s ostracode assemblages through time highlight the sensitivity of the lake and its benthos to hydroclimatic and environmental changes.