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VARIABILITY IN DIATOM AND CHRYSOPHYTE ASSEMBLAGES AND INFERRED PH: PALEOLIMNOLOGICAL STUDIES OF BIG MOOSE LAKE, NEW YORK, USA
Citation:
Charles, D., S. Dixit, B. Cumming, AND J. Smol. VARIABILITY IN DIATOM AND CHRYSOPHYTE ASSEMBLAGES AND INFERRED PH: PALEOLIMNOLOGICAL STUDIES OF BIG MOOSE LAKE, NEW YORK, USA. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-93/499.
Description:
The authors measured variability in the composition of diatom and chrysophyte assemblages, and the pH inferred from these assemblages, in sediment samples from Big Moose Lake, in the Adirondack Mountains of New York. eplicate samples were analyzed from (1) a single sediment. core interval, (2) 12 different intervals from each of 3 separate cores, and (3) 10 widely spaced surface sediment samples (O to 1.0 cm). he variability associated with sample preparation (sub-sampling, processing, and counting) was relatively small compared to between-core and within-lake variability. he relative abundances of the dominant diatom taxa varied to a greater extent than those of the chrysophyte scale assemblages. tandard deviations of pH inferences for multiple counts from the same sediment interval from diatom, chrysophyte, and diatom plus chrysophyte inference equations were 0.04 (n=8), 0.06 (n=32), and 0.06 (n=8) of a pH unit, respectively. tratigraphic analysis of diatoms and chrysophytes from three widely spaced pelagic sediment cor6s provided a similar record of lake acidification trends. verage standard deviation of pH inferences from diatom, chrysophyte, and diatom plus chrysophyte inference equations for eight sediment intervals rep3zesenting similar time periods but in different cores were 0.10, 0.20, and 0.09 pH unit, respectively. he data support the assumption that a single sediment core can provide an accurate representation of historical change in a lake. he major sources of diatom variability in the surface sediments (i.e., top 1.0 cm) were (1) differences in diatom assemblage contributions from benthic and littoral sources, and (2) the rapid change in assemblage composition with sediment depth, which is characteristic of recently acidified lakes.