An investigation of the bacterial community structure as a potential metric for environmental risk assessment

Bacterial communities are attractive indicators of environmental impact because they live in molecularly intimate association with their habitat and can respond rapidly to change. There are though, still substantial difficulties describing bacterial communities, and relating the data collected to ecological factors. In soils for example, there is a lack of association between bacterial divefOity and soil function. .. There is within microbiology a fascination with the rare species present in many habitats. However, most ecosystem activity will reside with the dominant species performing that class of activity. So, for example, most carbon turnover will be carried out by the dominant heterotrophs. Modern molecular methods provide data capable of describing the dominant bacterial populations in environmental samples. As a consequence of widespread use of these methods, there is no shortage of molecular data, but there is a shortage of concepts to adequately understand and exploit these data. In this thesis, a multi-disciplinary approach, combining classical ecology, and molecular microbial community analysis, was used to show for the first time that bacterial community responses to perturbation can be used as a metric for ecological risk assessment. I ,. demonstrated in this thesis that microbial communities in perturbed and control environments were fundamentally different at the level of community structure. This simple property of bacterial communities, combined with a simple and robust statistical measure provides clear criteria for determining an adverse effect. Thus bacteria may potentially be exploited as surrogates for higher organisms, by regulators seeking a generally applicable assessment of anthropogenic impact. Rank abundance analysis may also provide a measure of recovery as the effects of perturbation are ameliorated over time. This may be of particular relevance at sites where remedial treatment is being carried out since it is the microbial communities that are responsible for degrading pollutants in the environment and are thus key determinants of ecosystem health in contaminated environments.EThOS - Electronic Theses Online ServiceGBUnited Kingdo