IMPACTS OF MERCURY ON TESTATE AMOEBAE (ARCELLINIDA) OF CAYUGA LAKE, NY

Cayuga Lake is the second largest in the central New York State Finger Lakes region with a maximum depth of 132 meters (Oglesby, 1978). Two lakebed cores were taken from the same mid-lake location in 2013 and 2014, comprising 75 cm of the vertical sediment record, and correlated using % carbonate and THg. Testate amoebae were identified to strain after Kumar and Dalby (1998). Assemblages were assessed downcore and compared to the stratigraphy of total Hg. Mercury concentrations reach over 180 ppb downcore at 40 – 50 cm and correspond with high relative abundances of Difflugia oblonga “tenuis”, D. oblonga “oblonga”, D. protaeiformis “claviformis”, Centropyxis constricta “constricta”, C. constricta “aerophila” and C. aculeata “discoides.” These findings are supported by those of Peterson et al. (1996), reflecting the same assemblage composition as those found associated with mine tailings from Peterson and Crosswise Lakes in Cobalt, Ontario. Cucurbitella tricuspis, a species associated with the green algae Spyrogyra sp., is extremely abundant in pre-Hg peak sediments (comprising ~90% of the assemblage) and decreases at peak Hg. Difflugid abundances appear to reflect trophic status of the lake with the highest proportion of difflugids corresponding to the lake’s most eutrophic period from ~1950s – 1980s.