Dinoflagellate cysts and other NPP as paleolimnological proxies

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Many microscopic fossils survive harsh acid treatments that dissolve mineral sediments; these acid-resistant microfossils (palynomorphs) include the well-known pollen record of sediments that reflects the vegetation in the surrounding region as well as a wide variety of non-pollen palynomorphs (NPP) that include algae, fungi, animal, plant, and even bacterial remains. Because these have a variety of habitats and lifestyles (terrestrial/ aquatic; photosynthesizers/consumers/decomposers, bottom-dwellers/ swimmers and floaters), NPPs in a single sample provide a wealth of information about the entire lake ecosystem and its surrounding watershed. Unfortunately, relatively little is known about these microfossils and how their assemblages relate to the biological communities that produce them. The cysts of dinoflagellates will receive particular attention because we (at Brock) have exceptional expertise in this field. The relationship between the lake plankton and the resistant fossil dinocyst record is especially complicated; they often bear little resemblance to the cellulosic motile thecae. Combining a biological approach involving germination studies and DNA analysis with a micropaleontological (palynological) approach, this study will aid our understanding of the dinoflagellate life cycle and cyst-theca relationships. The NPP record of several dozen lakes from mid-latitudes in eastern North America will be compared with a) the flora and fauna in each lake and its watershed; b) physico-chemical conditions (e.g., temperature, pH, dissolved oxygen, nutrient levels, heavy metal concentrations) in the water column and on the lakebed, and c) other (non-acid-resistant) microfossils in the lakebed sediments. The aim is to illustrate the potential of this taxonomically and ecologically varied group in studies of water quality, particularly in assessing human impact on lake ecosystems, and ultimately to generate equations to quantitatively reconstruct the various environmental parameters that influence palynomorph distribution. Statistical analysis will determine the preferences and tolerances of each species that can then be used to reconstruct long-term changes related to natural factors (e.g., drought) and human activity (e.g., agriculture). Sediment cores also will be collected from a variety of lakes (large/small, urban/ remote, well-mixed/ stratified, well-buffered/ sensitive to acidification) with relatively well-known histories (based on historic records and other paleolimnological indicators), and the modern calibration dataset from surface samples will allow long-term environmental change to be reconstructed. The increase in abundance of ragweed and other weeds allows the identification of human impact, providing added chronological control to identify human-induced changes in water quality, augmenting radiometric ages.