Holocene environmental change at Laguna Saladilla, coastal north Hispaniola
Abstract We inferred environmental changes over the middle to late Holocene in coastal north Hispaniola using pollen, microscopic charcoal, mollusk shells, and diatoms in an 8.5-m sediment core from Laguna Saladilla, Dominican Republic (19°39′ N, 71°42′ W; ~ 2 m above sea level). Changes in Rhizophora (red mangrove) pollen percentages and in mollusk and diatom assemblages indicate major changes in salinity and water depth related to relative sea level rise and possible shifts in precipitation. Rhizophora percentages were highest at 7650 cal yr BP, when mollusk shells indicate the lake was connected to the Atlantic Ocean. Laguna Saladilla became progressively brackish ca. 3500 cal yr BP, and transitioned ca. 2500 cal yr BP to its current freshwater condition. High percentages of Amaranthaceae pollen and increased charcoal concentrations over the last ca. 2500 years signal dry climate and increased fires in coastal north Hispaniola. Geomorphological changes over time at Laguna Saladilla partially mask evidence of climate change in the proxies examined, and the record is equivocal before 2500 cal yr BP. Evidence for drier conditions since 2500 cal yr BP is consistent with late-Holocene shifts in the mean position of the Intertropical Convergence Zone (ITCZ) that have been identified on the Caribbean side of Hispaniola. We interpret the record as indicating that ITCZ migratory dynamics may also have affected precipitation on the Atlantic edge of the Greater Antilles.