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Appl Environ Microbiol. 1984 April; 47(4): 685-692
Copyright © 1984, American Society for Microbiology. All Rights Reserved.

Microbial Biomass and Utilization of Dissolved Organic Matter in the Okefenokee Swamp Ecosystem

Institute of Ecology and Department of Microbiology, University of Georgia, Athens, Georgia 30602

ABSTRACT

The Okefenokee Swamp exhibited levels of microbial biomass and aerobic glucose uptake comparable to those of other organically rich, detritus-based aquatic ecosystems. In contrast to other peat-accumulating systems, this acidic (pH 3.7), low-nutrient environment does not show diminished water column or surface sediment microbial biomass or heterotrophic activity. The total particular ATP varied between 0.03 and 6.6 µg liter^–1 (mean, 1.6 µg liter^–1) in water and between 1 and 28 µg g (dry weight)^–1 (mean, 10.0 µg g [dry weight]^–1 in sediments. The turnover times for dissolved D-glucose were 1.26 to 701.25 h (mean, 110.25 h) in aerobic waters and 2.4 to 72 min (mean, 10.2 min) in aerobic surface sediments. Water column bacterial secondary production, measured as the incorporation of [³H]thymidine into cold-trichloroacetic acid-insoluble material, ranged from 0.06 to 1.67 nmol liter^–1 day^–1 (mean, 0.45 nmol liter^–1 day^–1). The kinetics of D-glucose uptake by water column microflora are multiphasic and suggest the presence of a diverse microbial population capable of using labile substrates at nanomolar concentrations and at substantial rates. The presence of a large and active aerobic microbial community in the Okefenokee Swamp is indicative of an important role for microbes in swamp geochemistry and strongly suggests the existence of a detritus-based food web.

^* Corresponding author.

Okefenokee Ecosystem Publication no. 49.