Microbial Community Diversity, Structural and Functional Responses to Multi-Component Metal Contamination of River Benthic SystemsEPA Grant Number: R829400E02
Title: Microbial Community Diversity, Structural and Functional Responses to Multi-Component Metal Contamination of River Benthic Systems
Investigators: Holben, William E. , Gannon, James , Moore, Johnnie , Rillig, Matthias
Current Investigators: Gammons, Christopher H. , Hobbs, David , Moore, Johnnie , Nimick, David
Institution: University of Montana
Current Institution: University of Montana , United States Geological Survey [USGS]
EPA Project Officer: Chung, Serena
Project Period: September 24, 2001 through September 23, 2003 (Extended to September 22, 2004)
Project Amount: $280,000
RFA: EPSCoR (Experimental Program to Stimulate Competitive Research) (2000) RFA Text | Recipients Lists
Research Category: EPSCoR (The Experimental Program to Stimulate Competitive Research)
The research will develop detailed information about the composition, physiological activities, and chemical environment of microbial communities in river sediments contaminated with mine wastes. Experiments are designed to test 5 hypotheses: 1) initial exposure to metals inhibits or kills sensitive organisms, leaves tolerant populations as dominant, and produces an initial net decrease in diversity; 2) gradual changes in microbial community structure and function occur as the resident community becomes more tolerant of metals contamination; 3) decreased apparent toxicity from metal contamination occurs with prolonged exposure as a result of increased tolerance; 4) bacterial community changes can be indicative of the ecological health of watersheds because of the primary role bacteria play in biogeochemical processes and their basal position in ecosystem trophic structure; and 5) microbial communities respond to perturbation through changes in abundance of specific populations, or through altered patterns of physiological/metabolic activity.
The effects of metal contamination on microbial community diversity, structure, and function will be analyzed using geochemical and molecular techniques in a study whose features include: 1) combined field and mesocosm experiments to separate natural variation effects from metal effects; 2) assessment of the fungal component of microbial communities; and 3) assessment of the utility of monitoring bacterial communities as indicators of ecosystem health. Field-based research compares microbial communities in sites with varied levels of metals contamination using metals-impacted test-sites within the Clark Fork watershed in western Montana and similar unimpacted reference sites. Sediments at each site will be geochemically characterized seasonally in conjunction with detailed microbial community analyses. In situ experiments include biomass, lipid, activity analyses, and molecular biology methods to determine microbial community structure and function.
The overarching goal is to determine the effects of multi-component metal contamination on the structure and function of microbial communities in riverine sediments and to apply this knowledge to the development of strategies to accurately gauge injury to natural resources and monitor the effectiveness of remediation efforts. The connection between microbial stress and ecosystem productivity means that monitoring microbial community structure and function can provide important information on overall ecosystem health and underpin important ecological management decisions. This research will produce improved risk assessment of metals contamination in rivers and also facilitate better monitoring tools for different management or remediation practices at a fundamental ecosystem level based on bacterial community indicators.