| The objective of this study was to investigate changes at Anderson Pond in Middle Tennessee, using fossil diatom assemblages and to compare changes in the diatom assemblages to known changes in aquatic and local terrestrial vegetation in the context of late Quaternary climate change.;The fossil diatom assemblages indicate the presence of five diatom zones during the late Quaternary. The late-Pleistocene interval between 19,000 and 12,750 BP is dominated by the genus Fragilaria, characteristic of alkaline, high clarity water, with depths up to 6 meters. Between 12,500 BP and 10,000 BP, a new diatom assemblage establishes that is pH-indifferent, shallow-water epiphytic and epipelic, and dominated by the genera Eunotia, Pinnularia, and Stauroneis. The early to middle Holocene diatom assemblages from 9750 BP through 2250 BP are dominated by the acidophilous, epiphytic genera Eunotia and Gomphonema, indicating shallow-water levels with acidic water. From 2000 BP through 250 BP the diatom assemblages are dominated by the planktonic genus Aulacoseira, indicating expansion of shallow, open water pools with continued acidic pH levels and a decrease in water transparency. Modern sediment samples are dominated by the epiphytic genera Gomphonema, Eunotia, and Navicula indicating even shallower water levels and an increase in water pH to neutral conditions.;The disappearance of the Fragilaria-dominated assemblage between 12,750 BP and 12,500 BP coincides with a major change in upland forests from boreal jack pine and spruce to temperate oaks. The following three thousand years represent a period of cumulative changes in aquatic plant communities, associated with the expansion of a mosaic wet meadow grassland and swamp thicket. Eunotia reached dominance by 9750 BP and remained dominant until 2250 BP. The early Holocene rise in Eunotia is linked to the availability of an epiphytic substrate caused by early Holocene infilling of the basin and expansion of dense alder thickets. The rapid increase in Aulacoseira between 2250 BP and 2000 BP corresponds with a modest rise in water table and the expansion of open pools. The recent disappearance of Aulacoseira and the increase in Gomphonema, Eunotia, and Navicula resulted from human activity leading to increased sediment influx into the basin. |
