Relationships between bacterial productivity and organic carbon at a soil-stream interface

William V. Sobczak, Lars O. Hedin, Michael J. Klug

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


Microbial communities at soil-stream interfaces may be particularly important in regulating amounts and forms of nutrients that leave upland soils and enter stream ecosystems. While microbial communities are thought to be responsible for key nutrient transformations within near-stream sediments, there is relatively little mechanistic information on factors that control microbial activities in these areas. In this study, we examine the roles of dissolved organic carbon (DOC) vs. particulate organic carbon (POC) as potential controls on rates of bacterial productivity (measured as incorporation of [3H]thymidine into bacterial DNA) and amounts of bacterial biomass (measured as fatty acid yield) in sediments along a transect perpendicular to a soil-stream interface. We hypothesized that spatial patterns in bacterial productivity would vary in response to strong and persistent patterns in pore-water concentrations of DOC that were observed along a soil-stream transect throughout a 2-year period. Our results did not support the existence of such a link between pore-water DOC and bacterial productivity. In contrast, we found bacterial productivity and biomass were related to small-scale spatial variations in sediment POC on 3 of 4 sample dates. While our results indicate that total bacterial productivity in near-stream sediments is not consistently linked to spatial variations in pore-water DOC, it is likely that DOC and POC are not mutually exclusive and the relative contribution of DOC and POC to sedimentary microbes varies temporally and spatially in different riparian habitats.

Original languageEnglish (US)
Pages (from-to)45-53
Number of pages9
Issue number1-3
StatePublished - 1998
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Aquatic Science


  • Bacterial productivity
  • Dissolved organic carbon (DOC)
  • FAME yield
  • Particulate organic carbon (POC)
  • Riparian zone
  • Stream sediments


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