Longitudinal patterns of dissolved organic carbon concentration and suspended bacterial density along a blackwater river |
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Authors: | Francesc Sabater Judy L Meyer Rick T Edwards |
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Institution: | (1) Institute of Ecology and Zoology Department, University of Georgia, Athens, GA 30602, USA;(2) Present address: Department D'Ecologia, Universitat de Barcelona, Avgda. Diagonal 645, 08028 Barcelona, Spain;(3) Present address: Centre for Stream Ecology, Monash University, 900 Dandenong Rd., Caulfield East, Victoria, Australia, 3145 |
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Abstract: | Dissolved organic carbon (DOC) is the dominant form of carbon in transport in blackwater rivers, and bacteria are the major
biological agents of its utilization. This study describes longitudinal patterns in DOC concentration and relates them to
suspended bacterial populations in the channel. Concentrations of total DOC, three molecular weight fractions, and bacterial
numbers were determined at 12 sites along the Ogeechee River in 1985–1986 and 1989 during periods of low and high discharge.
Suspended bacterial populations were compared with DOC concentrations to determine if differences in bacterial abundance were
related to longitudinal patterns of DOC concentration. Three distinct longitudinal patterns were observed: (1) The longitudinal
pattern followed by both total and intermediate molecular weight DOC concentrations was a linear function of the geographic
distance along the river. (2) During low flow conditions, there was a high degree of correspondence between patterns of bacterial
numbers and low MW DOC (< 1000 apparent MW). (3) During periods of high discharge, the proportion of high (> 10,000) and intermediate
(1000–10,000) MW fractions increased, and there was no longer a clear relationship between bacterial cells and low MW DOC. |
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Keywords: | blackwater rivers DOC molecular weight fractions floodplains humic rivers longitudinal changes suspended bacterial cells |
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