Grant: Discovery Grants Program - Individual

Marine phytoplankton are unicellular, microscopic photosynthetic organisms found throughout the upper 100 m of the world's oceans. In aggregate they are responsible for about half of the total of all photosynthesis on Earth and provide the resources for the entire marine food web. Photosynthesis converts inorganic carbon to organic carbon and since some of the organic carbon sinks into the deep ocean, phytoplankton play an active role in removing CO2 from the atmosphere. Micro- and mesozooplankton are the primary organisms which mediate both trophic transfer and export of photosynthetic carbon to the deep sea. Many conditions in the oceans will change over the next century including temperature, surface wind speeds, the depth of the mixed layer, and the distribution of nutrient resources required by phytoplankton to grow. Thus changes in the productivity of plankton are expected with consequences for the marine food web and the biogeochemical cycling of carbon. Current knowledge of plankton physiology and ecology is insufficient to make credible projections of the anticipated changes.*I will use spatial and temporal surveys of plankton presence and abundance, together with environmental data such as temperature, salinity, the availability of resources, and mixing of the surface ocean to produce models describing the conditions favourable to each of dozens of phytoplankton and zooplankton species. These models can be used to both characterize the habitats favourable to each species and to project when and where each species will be found. These models can be used in several ways: (1) to fill in gaps in our very sparse sampling of the contemporary ocean and develop more detailed maps of plankton biogeography and seasonality, (2) to make projections of changes in the biogeography of plankton in the future ocean, guided by models of future ocean conditions, and (3) to study the extent these species distribution models are constant or are likely to change over time, for ecologically important phytoplankton and zooplankton species.*The work in this project will increase our knowledge of the base of the marine food web, help develop detailed hypotheses for changes in phytoplankton and zooplankton distributions over the coming century, and will guide developers of complex 3d ocean models as they improve the representation of plankton in these models.*