Grantee Research Project Results
UM SEER: Determining the Role of Microbial Community Structure and Function in Establishing the Health of Multicomponent-Metal Contaminated River Benthic Systems
EPA Grant Number: R827457E02Title: UM SEER: Determining the Role of Microbial Community Structure and Function in Establishing the Health of Multicomponent-Metal Contaminated River Benthic Systems
Investigators: Holben, William E. , Gannon, James , Moore, Johnnie
Institution: University of Montana
EPA Project Officer: Chung, Serena
Project Period: July 1, 1999 through June 30, 2002
Project Amount: $140,000
RFA: EPSCoR (Experimental Program to Stimulate Competitive Research) (1998) RFA Text | Recipients Lists
Research Category: EPSCoR (The Experimental Program to Stimulate Competitive Research)
Objective:
The proposed research focuses on the impact of metal contamination on the structure and function of microbial communities in riverine systems. We will test four hypotheses regarding effects of heavy metals on water and watersheds contaminated with metals from past mining operations:
- I) Initial exposure to metals inhibits or kills sensitive organisms leaving
tolerant populations as dominant, resulting in an initial net decrease in diversity.
II) Gradual changes occur in the microbial community over time as the resident community becomes more tolerant of metal contamination.
III) Decreased apparent toxicity from metal contamination occurs with prolonged exposure.
IV) These bacterial community changes have fundamental implications for determining the ecological health of watersheds because of the primary role bacteria play in a host of biogeochemical processes and their position at the base of the ecosystem trophic structure.
We will determine bacterial community response to metals contamination in terms of impacts on microbial community diversity, structure and function and assess the utility of monitoring bacterial community health as an indicator of overall ecosystem effects.
Approach:
The proposed studies, which compare impacted and unimpacted microbial communities in similar environmental settings, should provide important baseline information as to what constitutes a "normal" microbial community in riverine systems and how metals contamination affects microbial community diversity, structure and function. We have selected three test sites within a watershed severely impacted by multicomponent metal contamination representing high and moderate metals concentrations. Each site is matched with a reference site having the same hydrology, channel morphology, geology and climate. At each site, the water column and river substrate environments will be characterized geochemically in conjunction with detailed microbial community analyses. In situ experiments include biomass, lipid and activity analyses using incubation, extraction and radiolabel methods. Molecular methods will be used to establish microbial community structure using DNA isolated directly from environmental samples. Each analysis will be applied to natural and artificial substrates over a range of metal concentrations to determine the response of the bacterial community to a spectrum of multicomponent metals contamination.
Expected Results:
This project will provide important information regarding the use of microbial community structure and function as a fundamental indicator of ecosystem health by which we can assess trophic level changes in riverine systems. The rationale is that, as primary producers and consumers, microbes can serve as early indicators of perturbation in the ecosystem before effects are manifested at higher trophic levels. We will characterize bacterial community structure (molecular phylogeny analysis total community DNA fractionation), function (autotrophic and heterotrophic activities), and tolerance to heavy metals (lipid-based stress assessments, comparative community structure analysis, metal tolerance surveys) using modern physiological and molecular methods. Primary products of this research will be improved risk assessment of metal contamination in rivers and watersheds and monitoring responses to different management practices at a fundamental ecosystem level based on bacterial community indicator.
Supplemental Keywords:
ecological effects, bacteria, heavy metal, DNA, restoration, indicators, Northwest United States, Montana., RFA, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Waste, Water, ECOSYSTEMS, Hazardous, Ecological Indicators, Chemical Engineering, Ecosystem Protection, Environmental Chemistry, Ecosystem/Assessment/Indicators, Contaminated Sediments, exploratory research environmental biology, Monitoring/Modeling, Hazardous Waste, Ecological Monitoring, Ecological Effects - Environmental Exposure & Risk, Biochemistry, heavy metals, aquatic biota , bioremediation of soils, contaminated sediment, microbial degradation, biodiversity, ecosystem assessment, aquatic ecology, hazardous waste treatment, redox, ecological assessment, contaminated groundwater, ecosystem indicators, biodegradation, bioremediation, groundwater, biochemical indicators, environmental stress indicators, heavy metal contaminationProgress and Final Reports:
The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.