SS4.02 The Role of Microbiology in Trace Metal and Organic Contaminant Cycling in Aquatic Systems
Date: Wednesday, June 12, 2002
Location: Poster Session - VCC
 
SmutkaTM, University of Minnesota, St Paul, USA, smut0005@umn.edu
 
IDENTIFICATION OF TRACE NUTRIENT CONSTRAINTS ON BACTERIAL ABUNDANCE IN LAKE SUPERIOR
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The role of trace metals, particularly iron, as factors limiting phytoplankton growth in certain marine systems now seems well established. However, the potential of trace metals constraining bacteria, and especially freshwater bacteria, has not been as fully explored. I report here the results of two sets of metal-clean bioassay experiments designed to examine the role of iron and zinc on bacterial abundance throughout Lake Superior. The first experiments were conducted from water collected from 4 stations in the western arm of the lake between early June and late September, 2000, and consisted of nutrient amendments of C, Fe, Zn, and P. The second set of experiments was conducted from water collected from 2 stations near the middle of the lake in late May and late July, 2001, with light vs. dark treatments, and additions of P and a desferroxamine chelator. Counts conducted using epiflorescent microscopy indicate that P is the primary limiting nutrient, with strong secondary effects of Fe and Zn after the relief of P limitation.