Grant: Discovery Grants Program - Ship Time

Coastal aquatic environments, such as the St. Lawrence Estuary (SLE) in Eastern Canada, are productive ecosystems that support diverse biological communities, including commercially important marine life. In many respects, these ecosystems are sustained by the activity of microorganisms. For example, microbes are involved in the production and transformation of organic matter (OM), which influences global carbon (C) and nitrogen (N) cycles and controls the flow of energy and nutrients through marine ecosystems. Presently, the chemistry of the oceans is changing at a global scale due to human activity, which can lead to ocean acidification and hypoxia both globally and locally in the SLE. Understanding the factors controlling theses processes in relation to the C and N cycles requires a characterization of the structure and function of different bacterial communities thriving throughout the water column and the sediments. Here, we seek financial support to build upon several years of foundational research with an overall objective of expanding our time series work on the linkages between microbial community dynamics and C and N transformations in the SLE. We will combine novel sampling techniques, with functional genomics, microbiological, as well as organic and inorganic geochemical methods to better constrain the links between bacterial diversity/dynamics, OM cycling and oxygen concentrations along the fresh-salt water transition in SLE. We will collect samples for taxonomic and genomic studies. Moreover, we are building on our previous work by including an experimental functional genomics component, where we will manipulate the C and nutrient availability and track microbial responses in order to further characterize the microbial groups and metabolic pathways that underlie C and N cycling in the estuary. Our sampling effort is modest but critical as it will allow collecting live material to look at present-day dynamics of bacterial diversity, activity and dynamics. This information is pivotal to our understanding of bacterial dynamics along the salinity and oxygen gradients, and on how bacteria are affected by and affect OM chemical composition, reactivity and recycling in coastal systems.