Document: ROB-3-41-17

Testate amoebae as wetland paleoenvironmental indicators: A modern study of testate amoeba assemblages in Lake Superior coastal wetlands.

BOOTH, R.K.*, S.J.SCHOLL and S.T.JACKSON

University of Wyoming, Laramie, WY 82071-3165, USA 1

Abstract:
Testate amoebae are common inhabitants of lacustrine and wetland habitats. Fossil tests can be identified to species and recovered from sediments in quantities sufficiently large to permit estimation of relative abundances. The objectives of this study were to assess the potential of testate amoeba assemblages as paleoenvironmental indicators in Lake Superior wetlands and to determine whether morphological variation in four common taxa (Arcella spp., Assulina spp., Centropyxis cassis-type, and Nebela tincta-parvula-collaris group) has potential paleoecological applications. Study localities included ridge-swale wetland systems adjacent to Grand Traverse Bay and Tahquamenon Bay in the Upper Peninsula of Michigan. Testate amoeba assemblages from over 50 microsites at each locality were compared with percent moisture, depth to water table, pH, porosity, and plant species data. Morphometric analysis (e.g., test length, aperture diameter) was conducted on 25 individuals from at least 10 microsites for each of the four selected taxa. Gradient analysis techniques indicate that testate amoeba assemblages are controlled primarily by substrate moisture, consistent with results from other regions. Several species were found to be highly sensitive hydrological indicators (e.g., Nebela carinata, Lesquereusia modesta, Hyalosphenia subflava). Little relationship was found between microenvironmental parameters and morphological variation except for the Nebela tincta-parvula-collaris group where test size was significantly correlated with pH (r2=0.86). Results of this study indicate that wetland testate amoeba assemblages are potentially sensitive paleohydrological proxies, particularly in Sphagnum-dominated wetlands. Morphometric analysis of the Nebela tincta-parvula-collaris group may also have application in the long-term reconstruction of wetland pH.

Keywords: paleoecology, paleohydrology, testate amoebae

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This abstract is being presented at: 10:30 AM in session:
PALEOECOLOGY