The impact of oceanic microbial communities on marine biogeochemistry now and in the future

Interdisciplinary research on the diversity and function of microorganisms will be conducted in diverse marine water column environments in the Atlantic Ocean, ranging from the Bedford Basin, a nutrient-rich marine embayment, to nutrient-poor oceanic waters. Marine microorganisms have a large impact on the cycling of elements such as carbon, nitrogen, phosphorus and iron in the ocean. In particular the nitrogen cycle is mediated at every step by microorganisms. The research will focus on the cycling of nitrogen in the ocean, more particularly on the importance of N2 fixation. The availability of iron plays an important role in the biological transformation of nitrogen because many mediating enzymes require iron as a co-factor. Iron is a limiting nutrient in large areas of the ocean, leading to the accumulation of high dissolved inorganic nutrients in surface waters. It is important to understand how microorganisms have adapted to cope with low iron and this will be a second focus of the research. The communities of marine microorganisms in each environment studied will be characterized at the genomic and transcriptomic levels using pure cultures and natural assemblages of microorganisms. The research will yield a baseline of the functional genetic diversity of the communities of microorganisms in the Atlantic Ocean. This will provide a framework to understand how marine microorganisms influence ocean productivity and climate change through feedback processes between the surface of the ocean and the lower atmosphere. Ocean productivity is at the basis of fish production, and management of fish stocks requires understanding the factors controlling nutrient cycles and phytoplankton growth. The results will be important to assess and predict how the marine microorganisms will respond and evolve in the future ocean.