Tropical salt marsh succession as sea-level indicator during Heinrich events |
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| Authors: | Catalina González Lydie M Dupont |
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| Institution: | 1. Department of Palynology and Climate Dynamics, Albrecht-von-Haller-Institute for Plant Sciences, University of Göttingen, Untere Karspüle 2, 37073 Göttingen, Germany;2. Faculty of Oceanography, Federal University of Pará, Rua Augusto Corrêa, no 1, Guama, 66075-110 Belém, PA, Brazil;1. Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT 06511, USA;2. Leopold-Franzens-Universität Innsbruck, Institut für Geologie, Innrain 52, 6020 Innsbruck, Austria;1. Palynology & Paleoecology Lab, Botanic Institute of Barcelona (IBB-CSIC-ICUB), Pg. del Migdia s/n, 08038 Barcelona, Spain;2. Dep. of Environment, Earth & Ecosystems, Research Centre for Physical and Environmental Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK;1. State Key Laboratory of Marine Geology, Tongji University, 1239 Siping Road, Shanghai 200092, China;2. School of Life Sciences and Technology, Tongji University, 1239 Siping Road, Shanghai 200092, China;3. South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, China;4. State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China |
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| Abstract: | Centennial–millennial dynamics of tropical salt marsh vegetation are documented in the pollen record from marine core MD03-2622, Cariaco Basin, Venezuela, which spans the glacial period between 63 and 29 ka. Five rapid and abrupt expansions of salt marsh vegetation are linked with North Atlantic Heinrich events (HEs). Within each event, a recurrent pattern – starting with species of Chenopodiaceae, followed by grasses, and subsequently by Cyperaceae species – suggests a successional process that is determined by the close relationship between sea-level and community dynamics. The salt tolerant Chenopodiaceae, at the base of each sequence, indicate hypersaline intertidal environments, which were most likely promoted by extremely dry atmospheric conditions. Rapid sea-level rise characterizes the onset of HE stadials, causing erosion of marsh sediments, and continued recruitment of pioneer species (Chenopodiaceae), which are the only ones capable of tolerating the rapid rate of disturbance. Once, as sea-level drops or as rise decelerates, marsh plants are able to trap and stabilize sediments, favouring the establishment of more competitive species (graminoids). The increment of marsh height as a result of autochthonous sediment accumulation reduces the extent of hypersaline environments, and allows the establishment of mesohaline species. These results add to the scarce knowledge on tropical salt marsh ecosystems, and provide independent paleoclimatic evidence on sea-level changes occurring simultaneously with Antarctica climate variations. |
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