Dr Oscar Branson

Research Fellow
Researcher - Biogeochemistry
 +61 2 6125 9965

Profile

Qualifications

PhD, MSc, BSc Hons

Biography

Education

  • 2014 PhD Earth Sciences, University of Cambridge
  • 2010 MSc Oceanography, National Oceanography Centre, Southampton
  • 2009 BSc (Hons) Biology, University of Bristol

Employment History

  • Sept 2016 -                  Research Fellow, ANU
  • July 2014 - July 2016   Postdoctoral Researcher, UC Davis

Student Projects

The Biogeochemistry Group is always on the lookout for students. The few projects below are examples of specific projects we've got going on at the moment. If you're interested in doing something different, please get in touch!

Honours/MSc Projects

How to make a shell: vaterite stability and transformation in biominerals.

Foraminifera are a globally important group of marine calcifying organisms, whose shells provide one of our best geochemical archives of past climate. We recently found that they form their calcite shells via the metastable intermediate vaterite . This has major implications for understanding the formation and dissolution of foraminiferal tests and their geochemistry. This project consists of three parts, and would be expected to take 6-9 months: (1) collecting living foraminifera at sea and growing them in the lab, (2) working out how best to preserve metastable phases in the shells after the foraminifer dies, and then (3) characterising shell mineralogy and transformation with Infrared Spectroscopy and X-Ray Diffraction at the Australian Synchrotron in Melbourne.

Students with experience of chemistry/crystallography preferred.

Supervisors: Oscar Branson, Steve Eggins

PhD Projects

Tracking Reef Calcification: how much, where and who's calcifying/dissolving?

For a coral reef to exist, net CaCO3 deposition must be greater than its removal by physical erosion and chemical dissolution. Corals reefs don’t grow continuously. Huge changes in the rates of respiration, photosynthesis, calcification and CaCO3 dissolution occur on day-night and seasonal cycles, all of which need to be accounted for. To predict how coral reefs will fare in a high-CO2 world, we need to understand the specifics of this diurnal cycle, who the key calcifiers are, and how vulnerable they are to ocean acidification. The complexity of reef ecosystems makes this difficult. This project will separate the contribution of different components of the reef community, understand the dynamics behind net reef calcification, and investigate how these dynamics will change in response to ocean acidification.

The project will require field work at One Tree Island research station. It will involve making high-precision measurements of pH and Alkalinity, collecting water samples and making ultrahigh-precision [Mg] and [Ca] measurements, and performing dome isolation experiments to isolate the contributions of specific communities on the reef. The pH and Alkalinity data will be used to determine net photosynthesis/respiration/calcification/dissolution fluxes, and the [Mg] and [Ca] data will allow the student to identify which specific organisms are responsible for the calcification/dissolution signal. Together, these data provide a unique approach to quantifying the most important contributions to calcification and dissolution in natural reef environments. Once we’ve identified the key calcifying groups, we can test their response to ocean acidification, and work out where the ‘weak links’ are in the reef ecosystem.

Applicants should have a strong background in Marine Biogeochemistry and/or Aqueous Chemistry. Relevant lab/field experience would also be a plus.

Supervisors: Steve Eggins, Michael Ellwood, Oscar Branson

Research

Research interests

My research focuses on developing and applying novel, complementary techniques from material science and geochemistry to advance our fundamental understanding of the formation and dissolution of biominerals, the controls on their trace element composition, and their role in the oceanic biogeochemical response to past and future climate changes. Recent examples of this include using Atom Probe Tomography (APT) measure the atom-scale chemistry of biological templating structures embedded within carbonate biominerals, and using Synchrotron X-Ray Microscopes to measure the distribution and chemical state of boron and magnesium in the calcium carbonate shells of foraminifera. These experiments advance our fundamental understanding of bio-mineral interactions in biomineralisation, and probe the mechanisms behind two important palaeoceanographic proxies: the Mg/Ca palaeothermometer, and the B-based carbon system proxies.

My current research focuses on the biomineralisation of marine calcifying organisms, with specific interests in:

  1. Biological and mineralogical influences on the 'recording' of palaeoceanographic proxies.
  2. The role of organic components in controlling intra-skeletal chemical heterogeneity.
  3. The geochemical impacts of metastable precursor phases during biomineralisation.
  4. The sensitivity of marine calcifiers to climate change.

This involves laboratory-based mineral precipitation experiments, LA-ICP-MS and solution ICP-MS chemical measurements, Nano-SIMS and Atom Probe Tomography chemical mapping, synchrotron-based X-ray spectroscopy, diffraction and imaging techniques, and extensive field work and culturing of foraminifera, coraline algae and coral specimens.

Publications

Updated:  22 February 2018/Responsible Officer:  RSES Webmaster/Page Contact:  RSES Webmaster