PARENT SESSION
Oral Session # 82: Aquatic Ecology: Freshwater.
Presiding: A Soja
Thursday, August 7. 1:30 PM to 5:00 PM, SITCC Meeting Room 200.

Response of stream bacterial populations in biofilms to inorganic nutrients and dissolved organic matter.

Olapade, Ola^*,1, Leff, Laura^*,1, ¹ Kent State University, Kent, OH

ABSTRACT- The response patterns of bacterial taxa in stream biofilms developed on ceramic clay pots amended with dissolved organic matter (DOM) and inorganic nutrients were examined. We determined the abundance of different taxa, including Domain Bacteria, Cytophaga-Flavobacteria, and alpha, beta, and gamma Proteobacteria. Additionally, population sizes of bacterial species commonly found in stream biofilms (i.e. Pseudomonas putida, Acinetobacter calcoaceticus and Burkholderia cepacia) were examined. Clay pots amended with algal exudates, leaf leachate, glucose, phosphate, nitrate or a combination of phosphate and nitrate were placed in the Mahoning River during the summer and fall of 2002. After 3 weeks, samples were collected and preserved for fluorescent in situ hybridization (FISH), a technique used for the enumeration of different taxa. The responses among the three bacterial species were not significantly different to the presence of DOM and nutrients in both seasons. Among the three proteobacteria taxa, beta proteobacteria predominated, accounting for more than 40% of proteobacteria in all treatments, including controls. The results from the study reflect the need for a seasonal examination of community composition, in order to accurately represent the dynamics of response of bacterial populations to environmental variables, such as DOM and inorganic nutrients, in aquatic ecosystems.

Key words: biofilms, nutrients, bacteria, stream