PRELIMINARY EXAMINATION OF LAKE BIOLOGICAL RESPONSE TO CLIMATE CHANGE AND ANTHROPOGENIC DISTURBANCES, FOURTH LAKE OF THE FULTON CHAIN, ADIRONDACK MOUNTAINS, NORTHERN NEW YORK

Fourth Lake is one in a series of nine interconnected lakes located at 43N, 74W in the Adirondack Park. Mud-water interface cores were recovered in 2003 from the lake that spanned the past ~330 years and have previously been reported to display variations in grain size, magnetic susceptibility, charcoal, and carbonate content (Kanfoush 2005; 2006). Similarity of the patterns of variability with North American pollen-inferred temperature and precipitation and other climate records led to speculation that the lake sediment variations were a response in part to the North Atlantic Oscillation, the Atlantic Multidecadal Oscillation, and solar variability. However, development at Fourth Lake—like other areas in the Adirondack Park—is concentrated along the lakeshore. Consequently, this interpretation is confounded by high potential for anthropogenic disturbance to also influence lake sediment characteristics at this site.

Total diatoms were counted to determine if the lake has undergone changes in biological productivity over the past three centuries. A minimum of 400 valves were counted at 400x magnification. Preliminary results indicate total diatom concentration more than doubled from the base of the core dated at 1666 to the core top. Increased diatom productivity is supported by a more than 50% increase in organic carbon over the same interval. Such changes could be caused by either warming or increased nutrient input. However quantification of individual taxa such Cyclotella and Asterionella, which exhibit a similar response to warming (through reduced ice-cover duration and/or enhanced thermal stratification) but differing responses to nutrient loading, will be completed to ascertain relative contribution of the two potential drivers to temporal changes in the lake biology and sediment characteristics. Such information will aid policy makers in maintaining the health of the lake in the face of anticipated increases in both development pressure and climate change.