We inferred late Pleistocene and early Holocene (24-10 ka BP) environmental conditions in and around Lago Petén Itzá,Guatemala from ostracode remains in the lake sediments. Multivariate statistics were run on autecological information for 29 extant ostracode species collected in 63 aquatic ecosystems on the Yucatán Peninsula along a steep, increasing NW-S precipitation gradient and across a large altitudinal range. Conductivity and water depth are the most important factors that shape ostracode communities. Transfer functions were developed and applied to fossil ostracode assemblages in a ~76-m sediment core (PI-6, ~85 ka) taken in 71 m of water from Lago Petén Itzá, to infer past shifts in conductivity and water level. Results suggest climate was cold and wet during the Last Glacial Maximum (LGM). Alternating dry and wet conditions characterized the deglacial. Early Holocene climate was warmer and wetter. The LGM was characterized by low ostracode species richness (4 spp.) and abundance (<940 valves g-1), dominance of benthic over nektobenthic taxa, abundant Physocypria globula, conductivity as low as 190 μS cm-1, and clay-rich sediments with relatively high total organic carbon and low C/N ratios (<14), suggesting relatively deeper water at the core site associated with abundant precipitation. Greatest water depth at the core site during the LGM occurred late in the period and was ~50 m. The deglacial was characterized by drier conditions, higher ostracode species richness (6 spp.) and abundances up to 18,115 valves g-1, dominance of nektobenthic species, and presence of shallow-water and littoral-zone indicators such as Heterocypris punctata and Strandesia intrepida, conductivity up to 550 μS cm-1, C/N ratios as high as 37, and gypsum deposition. Lowest inferred lake depth at the core site during the deglacial was ~20 m. The early Holocene was characterized by high numbers of ostracode remains, up to 25,500 valves g-1, and the presence of L. opesta and P. globula. Cytheridella ilosvayi was absent from late Pleistocene sediments, suggesting it colonized northern Central America during the Holocene.
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Acknowledgments We thank all those who facilitated fieldwork in Mexico, Belize and Guatemala. Special thanks to: Andreas Müller and other participants in the Petén Itzá Scientific Drilling Project, Aaron Lewis (University of Belize), the Forestry and Fisheries Departments (Belize), Margarita Palmieri, Margaret Dix, Roberto Moreno, Eleonor de Tott (Universidad del Valle de Guatemala), Rodrigo Morales, Franklin Herrera (CONAP, Guatemala), Ismael Ordóñez (AMSCLAE, Guatemala), Julio Morales Cancino (AMPI, Guatemala), Roderico Pineda, Mario Buch (Trifinio, Guatemala), Gerald Islebe (ECOSUR-Chetumal, México), Secretaría de Relaciones Exteriores (SRE, México), Comisión Nacional de Acuacultura y Pesca (CONAPESCA, México), Alberto de Jesús Navarrete (ECOSUR-Chetumal, México), the National Lacustrine Core Repository (LacCore, University ofMinnesota), Julia Lorenschat, Rita Bugja, Rita Löhr, Benjamin Gilfedder, Yvonne Hermanns, Harald Biester (Institut für Umweltgeologie, Braunschweig), Dietmar Keyser (Zoologisches Institut und Zoologisches Museum, Hamburg), Steffen Mischke (Freie Universität Berlin), Douglas Schnurrenberger, Dustin Grzesik, David Klassen, Luciana Mitsue, José Harders, Carmen Herold, Bessie Oliva, Alma Quilo, Gabriela Alfaro, Jacobo Blijdenstein, Melisa Orozco, Silja Ramirez, Luis Toruño, Mario Cruz, Javier Pérez y Pérez, and Carolina Alvarado de Pérez. The Deutsche Forschungs-gemeinschaft (DFG, grant Schw 671/3) and the Technische Universität Braunschweig provided financial support.
Copyright 2011 Elsevier B.V., All rights reserved.
- Environmental change
- Lago Petén Itzá
- Late Pleistocene
- Non-marine ostracodes
- Training set
- Transfer function
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