Key Processes in the Holocene Evolution of Tropical Coasts - Evaluating the Role of Hurricanes and Tsunamis

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Being a coral island situated in the semi-arid tropics, Bonaire (Netherlands Antilles) is excellently suited as bio- and geoarchive for studying the record of extreme events. Alt such signatures stored in ramparts, rubble ridges, boulder fields, etc. are well datable by 14C-AMS and ESR with high precision. Moreover, Bonaire's lagoonal systems and near shore lakes contain continuous sedimentary records since approx. 6000 yrs BP. The project aims to identify the driving forces responsible for the Holocene evolution of Bonaire's tropical limestone coast and its ecosystems. The impact of sudden and high-magnitude extreme events (hurricanes and tsunamis) is compared to steady, continuous and low-magnitude (non-extreme) forming processes. To achieve this goal the Holocene history for both process types is deciphered by the analysis of sediment cores in near shore geoarchives and the study of coarse deposits onshore. The geochronological framework is built by ESR and Radiocarbon dating. The response of the coastal ecosystems (coral reefs, mangroves) to extreme events in terms of adaptation/regeneration, phase shifts or extinction is a vital component of the project. Near shore bio-geoarchives store marine and terrestrial records. Their interrelationship will be studied with a multi-proxy approach. Overall, we aim to establish the island of Bonaire as a prototype region for tropical coasts where extreme events act as key processes in the coastal evolution.