TESTATE AMOEBAE AND OTHER MICROFOSSILS OF LAKE GEORGE, NY: UNDERSTANDING THE MODERN ANALOG

Testate amoebae continue to grow as useful paleoecological indicators, particularly as proxies for pollution, eutrophication (Roe et al., 2010; Patterson et al., 2012), low oxygen (Asioli et al., 1996), alkalinity, and pH levels (Escobar et al., 2008). They have been documented as predominantly useful in stressed environments including lakes impacted by mines (Kihlman, 2012) and oil sands (Neville et al., 2011). Other records indicate application for biostratigraphic and climate studies (McCarthy et al., 1995), as well as correlation with various vegetation zones (Neville et al., 2010). Clearly, these single-celled, polyphyletic organisms with fossilizable tests are a valuable asset in paleo-reconstructions.

Because species occur in a wide range of environments and have been linked to a variety of ecological parameters, interpretations sometimes conflict. For example, Arcellasp. is documented as a taxon that prefers clean waters (Burdiková et al., 2012) yet also dominates stressed environments such as lakes with high levels of heavy metal contamination or brackish conditions (Patterson and Kumar, 2000). Thus, studying modern assemblages of this emerging proxy strengthens interpretations of the paleo fauna.

Lake George, NY is a unique lake in the Adirondack Park because it has a long-term (30 yr) water quality record, measured by RPI’s Darrin Freshwater Institute. The lake is oligotrophic, but recent measurements indicate trends toward eutrophication and a decline in other water quality parameters, offering a unique opportunity to link testate amoebae to known constraints throughout the lakebed in a relatively healthy environment compared to the majority of previous testate amoebae studies. In our study, assemblages are analyzed from ~35 widely distributed surface sediment samples and compared to water quality measurements. Diatom, pollen, and non-pollen palynomorphs are analyzed for cross-verification of testate amoebae interpretations. Our work is a pioneer assessment of these taxa from the modern lakebed and illustrates geographic variability from anthropogenic influence. These data will later be applied to down-core assemblages to reconstruct the water quality history of Lake George. The establishment of these assemblage chronologies will contribute to remediation goals and monitoring.