--> --> Ecological Evidence of Holocene Flooding and Eutrophication in Texas Bays

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Ecological Evidence of Holocene Flooding and Eutrophication in Texas Bays


High rainfall events in the Southern US can cause lasting damage on local infrastructure and communities. Diatom blooms often occur in coastal systems that drain major rivers due to fertilizer runoff and increased nutrient supply, which can in turn have impacts on ecological communities and the fishing industry. While recent observations address these relationships, natural flooding frequency and hydrological and biological impacts are poorly understood. Our preliminary research targets the Holocene record of diatom blooms in Galveston and Corpus Christi bays, which drain major metropolitan centers of Texas. Sediment cores spanning the Mid and Late Holocene from these bays are sampled for diatom abundance and assemblage and studied in conjunction with published grain size and radiocarbon ages. Trace elemental composition is used to approximate onset and expansion of industrialization in the region. Palynofossils are used to help estimate runoff and interpret climate and environment. Studies of cores collected from Lake Macatawa, Michigan in the 1970's highlight the viability of using diatom frustrules from core to reconstruct flooding histories, given their environmental sensitivity and high preservation potential in Holocene sediment. Studying the long-term frequency and severity of flooding and associated eutrophication events will ultimately help illuminate the impacts of climate and land use change on coastal environments. Furthermore, our study of phytoplankton blooms in recent sediment with good control may help our understanding of restricted, high nutrient marine environments of the past, where blooms and oligotrophy are associated with hydrocarbon generation.