Late Holocene Paleosalinity, Groundwater Discharge, and Regional Climate Change at Celestun Estuary, Yucatan Peninsula, Mexico

Multiple studies have attempted to reconstruct Quaternary climate variability in Meso-America and the Caribbean region conditions may drive climate on a global scale and by the realization that the region is well-placed to track past shifts in the average position of the Intertropical Convergence Zone (ITCZ), which is a major control on precipitation and drought occurrence in tropical and sub-tropical areas of the world. With this in mind, we seek to develop a new record of late Holocene paleosalinity, freshwater input and environmental change at Celestun Estuary, on the northwestern coast of the Yucatan Peninsula. Our paleosalinity reconstruction is based on the oxygen isotope (d18O) composition of tests of the benthic foraminifer Ammonia beccarii separated from sediment cores collected at several sites in the estuary, while we infer other environmental changes based on foraminiferal assemblages and the carbon and nitrogen abundance and isotope compositions (d13C, d15N) of sedimentary organic matter from these cores. The groundwater that dominates freshwater input into Celestun is recharged over a large area of the northern Yucatan, suggesting that a record of paleosalinity and groundwater discharge at Celestun will integrate a regional climate signal. We will present modern correlations between salinity and δ18O of both the water column and core-top benthic foraminifera from sites along a head-to-mouth transect as a means of tracer calibration, as well as down-core results from longer cores (1.5 - 3 m) collected in the upper, middle, and lower estuary.