The fossil record of freshwater dinoflagellates and green algae in paleoenvironmental studies

***单片“花粉片”中的非花粉孢粉形态（NPP）提供了整个湖泊生态系统和周围流域的信息。尽管它们普遍存在，即使是在缺乏矿化微化石的沉积物中，但花粉分析者通常会忽略或提及藻类的形态。我和我的学生将结合生理/湖泊学和孢粉学/古湖泊学的方法，通过研究：******1)与H Gu（厦门）合作，利用萌发研究和rDNA测序，对藻类的孢粉形态进行分类。这些发现将应用于与不同同事合作的淡水藻类进化研究以及我们的古湖泊学研究。******2)环境对藻类形态的控制，将湖床组合与测量的环境变量联系起来。该研究的一个关键方面是将校准数据集从安大略省西北部实验湖区的30个湖泊扩展到北美东部的其他地区；这将调查气候和地质对孢粉记录的意义，目的是发展区域转移函数，以便定量重建水质。与伦斯勒理工学院（Rensselaer Polytechnic， RPI）的合作者进行了多代理调查，并将进行湖底研究，以评估纽约乔治湖的变异性。******3)在不同的大小、深度、地质、水文、人类对湖泊和流域的影响等方面，比较一年中不同时间的湖床样品、沉积物陷阱和浮游生物拖带组合，从而使孢粉记录相对于生理记录产生偏差。博士生A Krueger继续进行季节性采样（包括最近在大型中营养型湖泊乔治湖的连续监测点部署的陷阱）将使我们能够将湖床沉积物与多年来的浮游植物生产力和测量的湖泊参数联系起来。与研究浮游动物和其他浮游植物群的研究人员合作，将有助于深入了解捕食和竞争对藻类种群的“自上而下”影响。*** ***这些发现随后将应用于下岩芯和露头研究，以重建与温暖（末次间冰期）和干燥（8.2 k事件）气候以及人类影响相关的湖泊变化。这将使我们能够评估预计的气候变化和人口增长对大湖地区水质和水量的影响。提高对NPP空间分布和地层学的理解也将应用于研究富有机质湖泊的异常沉积事件，使我们能够评估NPP作为突发性自然灾害指标的使用。这将在古地震学和古风暴学研究中有潜在的应用。********

***Non-pollen palynomorphs (NPP) in a single “pollen slide” provide information about the entire lake ecosystem and surrounding watershed. Despite their common presence, even in sediments that lack mineralized microfossils, algal palynomorphs are typically ignored or mentioned in passing by pollen analysts. My students and I will combine phycological/ limnological and palynological/ paleolimnological approaches to promote their use as paleolimnological proxies by studying: ******1) the taxonomy of algal palynomorphs, using germination studies and rDNA sequencing, in collaboration with H Gu (Xiamen). These findings will be applied to studies of the evolution of freshwater algae in collaboration with various colleagues aw well as to our paleolimnological studies.******2) the environmental control on algal palynomorphs, relating lakebed assemblages to measured environmental variables. A key aspect of the proposed research is to expand the calibration dataset beyond the 30 lakes in the Experimental Lakes Area of NW Ontario to other parts of eastern North America; this will investigate the significance of climate and geology on the palynological record, with the aim of developing regional transfer functions to allow quantitative reconstruction of water quality. Intrabasinal studies will also be conducted to assess variability across Lake George NY, in a multiproxy investigation with collaborators from Rensselaer Polytechnic (RPI).******3) the taphonomic factors that skew the palynological record relative to the phycological record, comparing lakebed samples with sediment trap and plankton tow assemblages at different times of year in lakes that vary in size, depth, geology, hydrology, human impact on the lake and watershed, etc. Continued seasonal sampling by PhD student A Krueger (including traps recently deployed at continuous-monitoring sites in the large, oligo-mesotrophic Lake George) will allow us to relate lakebed sediments to phytoplankton productivity over multiple years and to measured limnological parameters. Collaboration with researchers studying zooplankton and other phytoplankton groups will provide insights into the “top-down” effects of predation and competition on algal populations.*** ***These findings will then be applied to downcore and outcrop studies to reconstruct limnological changes associated with both warmer (last interglacial) and drier (8.2 k event) climates and with human impact. This will allow us to assess the impact of projected climate change and population growth on water quality and quantity in the Great Lakes region. Improved understanding of the spatial distribution of NPP and taphonomy will also be applied to studying unusual sedimentation events in organic-rich lakes, allowing us to assess the use of NPP as proxies of sudden-impact natural hazards. This will have potential applications for paleoseismological and paleotempestological studies.********