Microbial biodiversity-ecosystem function relationships in marine reducing habitats

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Over the past 2 decades, marine ecology has seen a shift in focus from documenting biodiversity to wanting to understand the importance of biodiversity to the services that marine ecosystems contribute to human society and to our planetary support system. Ecologists assign functional traits or 'ecosystem job descriptions' to species and groups of species that define their role in ecosystems, from photosynthesis, nutrient cycling and predation to the production of fish stocks. On the other hand ecologists who study marine microorganisms have been comparatively slower to make this change in perspective. In part, this is because new, high throughput gene sequencing methods are providing marine microbiologists with information at a level that surpasses the development of meaningful ecological interpretation. This research program will focus on marine reducing habitats, where changes in dissolved oxygen cause shifts in microbial composition and metabolism. These gradients of environment change provide opportunities to directly observe relationships between microbial diversity, and the metabolic processes that microbes contribute to ecosystem function. Over the past several years my laboratory has developed or implemented a number of analytical tools that will be brought to bear on this question. A PhD student will study how seasonal changes in dissolved oxygen levels influence microbial community diversity, and the diversity of a particular group that causes nitrogen loss from marine ecosystems, in Saanich Inlet, a fjord on southern Vancouver Island. Two other students (PhD an MSc) will examine how marine microbes colonize habitats formed by other organisms. This ecological facilitation' creates hot spots for the concentration of microbial growth and chemical transformations that are important to ecosystem function. A 3rd PhD student will study the ecosystem role of protists, single-celled animals, at deep-sea hot springs. Our understanding of protists in these unique ecosystems is very limited. We thus begin with fundamental questions about where protist species are found at vents, the existence of a vent-specialized group of protists, and questions about how habitat conditions determine protist diversity and distribution in different hydrothermal habitats. This survey work will use gene sequence information to assess protist diversity in different vent habitats and identify key players. This basic taxonomic information will be used to construct functional portraits of vent protist communities, based on current knowledge and a new online database. It is easier to count species than to determine what they do in ecosystems, even for microbes. A postdoctoral fellow will join the project in the final year to synthesize data from all projects, and evaluate what biodiversity information can tell us about how marine microbes contribute to ecosystem services.