Microbial heterotrophy in reducing habitats

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Microorganisms play a vital role in marine ecosystems by recycling organic matter and nutrients through their decomposition activity. We know in a general way that communities of marine microbes adapt to changes in their environment by adjusting their metabolic pathways (functional response) or by changing their species composition (structural response). This research program will examine the relative importance of these two types of response, under different types of environmental forcing, in the extreme habitats found at deep-sea hydrothermal vents and in an anoxic fjord. We will compare these response mechanisms by enzyme and genetic fingerprinting of microbial samples collected from contrasting vent habitats, and from different points in the cycle of anoxia and re-oxygenation of the deep waters of the fjord. This research will have applications for understanding microbial community dynamics in coastal waters subject to nutrient loading stress from sewage and aquaculture.  Oxygen consumption and hydrogen sulphide production by seafloor microbial communities can profoundly affect habitat suitability for fish and invertebrates.