Associate Professor Michael Ellwood Ellwood

BSc (Hons), PhD
Senior Fellow/Associate Professor
ANU College of Science
T: 02 61258322

Areas of expertise

  • Biological Oceanography 040501
  • Chemical Oceanography 040502
  • Analytical Chemistry 0301
  • Oceanography 0405

Researcher's projects

1) Microscopic plankton form the base of the marine food-chain and account for more than half of global primary production, and hence moderates our climate through the ocean's ability to drawdown carbon dioxide. In this project, the sources and bio-availability of the key micro-nutrient, iron, and its influence on plankton productivity in the surface ocean will be investigated by making state-of-the-art iron isotope measurements on plankton and waters samples collected from the Tasman Sea region. The knowledge generated in this project will help elucidate future impacts and feedbacks desertification of continental Australian and ocean stratification have on the supply and cycling of iron in the marine realm.

 

2) This research will reconstruct the distribution of nutrients in the Southern Ocean using the isotope and trace element composition of fossil marine skeletons of  siliceous and carbonate organisms. Understanding the distributions of key nutrients such as phosphate, nitrate and silicate in the surface and deep ocean is essential to understand the mechanisms by which marine algae influenced the drawdown of  atmospheric carbon dioxide during the past. These links between nutrients, productivity and carbon dioxide are critical to understanding future climate change and its connection to increases in atmospheric carbon dioxide concentration associated with fossil fuel burning.

Available student projects

The Southern Ocean is of global importance as it plays a key role in regulating atmospheric carbon dioxide (CO2). However, phytoplankton growth in Southern Ocean waters is sub-optimal as a result of chronic iron limitation, thus their ability to draw down CO2 during photosynthesis is limited. As iron availability critically underpins the structure, functioning and productivity of marine ecosystems a pressing challenge is to quantify the complex interplay between physical iron supply, its chemical and photochemical transformations, and the biological uptake and recycling of iron in the ocean. In this project, the sources and bio-availability of iron and its influence on plankton productivity in Southern Ocean waters will be investogated. To trace these changes iron isotope ratios as a diagnostic tool to fingerprint the biogeochemical cycle of iron in Southern Ocean waters.

The aims of this project are to develop a mechanistic understanding of:

  • the cycling of iron in Southern Ocean surface waters and the modes by which iron is recycled between phytoplankton and bacteria
  • how phytoplankton, zooplankton and bacteria acquire iron via reductive processes
  • how iron bioavailability manifests through to the cellular uptake of other biologically important elements (e.g. zinc and silicon) by phytoplankton
  • how a changing Southern Ocean will influence iron demand and assimilation by phytoplankton and what will be the consequent effects on iron biogeochemistry.

To do this will involve:

  1. culturing Southern Ocean phytoplankton under a matrix of iron and environmental conditions to determine nutrient and trace metal uptake kinetics and cellular content;
  2. undertaking ship-board manipulation experiments involving the resident Southern Ocean

Publications

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Updated:  12 November 2019 / Responsible Officer:  Director (Research Services Division) / Page Contact:  Researchers