Doctoral Dissertation Research: Multi-Proxy Paleoecological Records from the Shark River Estuary: Wetland Evolution in the Light of Paleohurricane Activity and Sea-Level Changes

这项博士论文研究项目将研究沿海湿地群落对过去海平面波动和反复发生的飓风袭击的长期反应，以揭示佛罗里达州西南部大沼泽地红树林的全新世历史。该地区目前尚无距今5000年前的孢粉记录。这位博士生将通过整合包括孢粉学、X射线荧光和点火损失分析在内的各种古生态方法来帮助填补这一空白，以产生过去7500年来第一个花粉记录和古飓风代理记录，并揭示沿海大沼泽地最古老的沉积史。对14-碳、137-铯和210-铅的放射性同位素分析将用于从鲨鱼河滩沿岸和附近收集的沉积物样本的年代测定。对之前在鲨鱼河口收集的沉积物岩心的分析发现，飓风威尔玛具有独特的地层特征。威尔玛是一种强烈的飓风，于2005年直接袭击了研究地区。这一风暴沉积物将被用作现代模拟，用于识别其他核心的其他飓风事件。对这些岩心的分析以及由此产生的植被年表应该有助于揭示红树林对过去海平面上升和飓风干扰的反应。大沼泽地的沿海红树林是一种重要的自然资源。通过将孢粉学和古温学相结合，这项研究的结果将揭示红树林生态系统对几个世纪到几千年的时间尺度上的多种极端事件的反应。这样一个数据库涉及管理和恢复大沼泽地沿海生态系统的两个关键问题：海平面迅速上升和极端飓风扰动。孢粉学结果将为海岸保护和恢复的管理规划提供指导方针和背景知识。该项目还应有助于确定南佛罗里达州灾难性飓风的频率，这对该地区的风险评估和灾害管理至关重要。作为博士论文研究改进奖，该项目将为有前途的学生建立独立的研究生涯提供支持。

This doctoral dissertation research project will examine the long-term response of coastal wetland communities to past sea-level fluctuations and recurrent hurricane strikes to reveal the Holocene history of mangrove forests in the Everglades of southwestern Florida. No palynological record older than 5,000 years before the present currently exists for this region. The doctoral student will help fill this gap by integrating various paleoecological methods including palynological, x-ray fluorescence, and loss-on-ignition analyses to produce the first pollen record and paleo-hurricane proxy record over the past 7,500 years and reveal the oldest depositional history of the coastal Everglades. Radioactive isotope analyses of 14-carbon, 137-cesium, and 210-lead will be used to date sediment samples collected from locations along and near the Shark River Slough. Analyses of a sediment core previously collected at the mouth of the Shark River Slough had identified a distinctive stratigraphic signature for Hurricane Wilma, an intense hurricane that directly struck the study area in 2005. This storm deposit will be used as a modern analog for identifying other hurricane events in other cores. Analyses of these cores and the resulting vegetation chronologies that will be produced should help reveal the response of mangrove forests to past sea-level rise and hurricane disturbance.Coastal mangrove forests in the Everglades are an important natural resource. By coupling palynology with paleotempestology, the results of this study will shed light on the response of the mangrove ecosystem to multiple extreme events over timescales of centuries to millennia. Such a database addresses two key issues in the management and restoration of the Everglades coastal ecosystems: rapid sea-level rise and extreme hurricane disturbances. The palynological results will provide guidelines and background knowledge for management planning for coastal protection and restoration. This project also should help identify the frequency of catastrophic hurricanes in South Florida, which is information vital for risk assessment and disaster management in the region. As a Doctoral Dissertation Research Improvement award, this project will provide support to enable a promising student to establish an independent research career.