Phytoplankton Ecology

As the base of the marine food web, phytoplankton is comprised of a great variety of living, planktonic, unicellular algae in the ocean. In high-latitude environments, particularly in the Southern Ocean, the Arctic Ocean, and areas in their vicinity, phytoplankton is responsible for providing food to animals and bacteria in the form of newly synthesized organic carbon. Different from plankton at lower latitudes where bacteria and dissolved organic carbon dominate, most of the organic carbon in surface waters of polar oceans during the growth season is in particulate form, and dominated by phytoplankton biomass.

Ecology of polar phytoplankton includes a diverse line of topics including:

  • description of species within plankton assemblages or community diversity
  • determination of biological processes of phytoplankton production and loss rates to understand their contribution to the carbon cycle
  • temporal and spatial variability of a particular species or total biomass and their relationship to environmental forces
  • experimentation with radiation or nutrients to interpret phytoplankton distribution in relationship to water masses or stratification from surface to deeper waters

Research within these topics contributes to our ability to predict phytoplankton responses to light quality and quantity, or other environmental parameters which ultimately relates phytoplankton abundance and composition to the carbon available to benthic communities. Studies particular to polar phytoplankton include growth at low temperature and adaptation to low or no light in the winter, exchange of algae between sea ice and surface waters and determination of communities associated with the sea ice edge or free-floating icebergs. Many of these topics will be investigated in the FjordEco project.

Dr. Maria Vernet leads the phytoplankton ecology team from Scripps Institution of Oceanography. This team is investigating the productivity of Andvord Bay with a focus on how the physical and chemical dynamics in this ecosystem affect the phytoplankton community, overall productivity and how this translates into flux to the benthos.

Glaciomarine fjords along the West Antarctic Peninsula are different from other productive Antarctic shelf locations (e.g. Marguerite Bay, Arthur Harbor) in that the fjords, like Andvord Bay, contain shallow sills which isolate deep inner basins from the outer shelf. This feature can not only augment the flow within the fjord but interaction of flow with the sill can locally enhance phytoplankton biomass. It is expected these interactions affect nutrient concentrations in both space and time and is likely a major driver behind seasonal autumn blooms observed within the fjords. Further, as the phytoplankton community is dominated by large diatoms, the flux of nutrient-rich material to the benthos varies as a function of the seasonal productivity. Preliminary results suggest that these fjords harbor high productivity throughout the year possibly supporting an abundant and diverse community of fauna.

To fully understand these dynamics, the phytoplankton ecology team will be collecting nutrient concentration data from Conductivity Temperature Depth (CTD) profilers, autonomous gliders, collect sea-ice algae, use physical oceanographic data collected by moorings and towed instruments, and conduct at-sea productivity experiments.

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