Associate Professor Helen Bostock Lyman

Associate Professor in Oceanography

School of Earth and Environmental Sciences
Faculty of Science
h.bostock@uq.edu.au
+61 7 336 56082

Overview

The focus of my research is on the oceanography and paleoceanography. I use stable isotopes (oxygen, carbon, boron), geochemical tracers, sedimentology and microfossils to understand the present and past changes in ocean chemistry to reconstruct ocean circulation (changes in ocean currents and fronts) and its relationship to global climate. I am particularly interested in understanding past changes in the Great Barrier Reef, and at the other extreme past changes in processe at the Antarctic Margin. I am also interested in mapping marine sediment distribution, sediment transport processes, marine geomorphology, and multidisciplinary topics such as ocean acidification (the uptake of CO2 by the oceans) and climate change in the oceans (marine heat waves, sea level rise), and paleoseismicity (using sedimentary records to reconstruct the history of past earthquakes). My research has focussed on the southwest Pacific (Coral Sea, Tasman Sea and South Pacific) and Southern Ocean. I have participated in a number of research voyages, including several as lead or co-lead.

Helen Bostock joined the University of Queensland in July 2019 from the National Institute of Water and Atmospheric Research in New Zealand (2006-2019). Prior to this she worked as a researcher in the Coastal CRC at Geoscience Australia in Canberra (2004-2006).

Research Interests

  • Past changes in the Southern Ocean
    I am interested in past changes in ocean circulation in the Southern Ocean over glacial/interglacial timescales (1000s-100,000s years). I use proxy evidence from sedimentary characteristics, microfossil assemblages, stable isotopes (carbon, oxygen, nitrogen and boron), elemental variations from a latitudinal transect of marine sediment cores from the subtropical waters of the southwest Pacific to the continental margin of Antarctica. I try to reconstruct changes in temperature, biological productivity, changes in water masses, ocean currents and fronts, sea ice, ice sheet retreat, and how all these different processes are linked to global climate.
  • Geological history of the Great Barrier Reef
    I am interested in the initiation and development of the Great Barrier Reef using proxies (sedimentology, microfossil assemblages, stable isotopes, geochemistry) from marine sediment cores offshore. The aim is to understand the timing of the reef development, but also to understand the broader regional ocean circulation of the Coral Sea over glacial/interglacial timescales (1000s-100,000s-1,000,000 years).
  • The carbon cycle in the ocean and ocean acidification
    I look at the geochemistry of the water column, primarily the carbonate chemistry and carbon isotopes, to understand changes in the ocean carbon cycle over recent decades due to the uptake of anthropogenic CO2 from the atmosphere. This results in a decline in the pH in the ocean, a process known as ocean acidification. I also work with collaborators using Boron isotopes of microfossils in marine sediment cores to understand how pH and carbonate concentrations have changed over glacial/interglacial timescales.
  • Sedimentary processes in the ocean
    I look at the distribution of sediment in the marine environment from coastal to the deep ocean. The sediment type is dependent on the local source from nearby rivers, as well as biological productivity (e.g. shells and skeletons) and authigenic sediment (geochemically precipitated out of the seawater). Sediment is redistributed by gravity and ocean currents. The distribution of sediment in the marine environment is important to determine marine benthic (seafloor) habitats. The recurrence of gravity transported sediment (called turbidites or debrites) along tectonically active continental margins has been used to study the frequency of large earthquakes.

Research Impacts

The work undertaken as part of the Coastal CRC (https://ozcoasts.org.au/) looked at several different coastal enviroments around Australia to understand the impact of recent sediment and contaminants on the local ecosystems, such as the Great Barrier Reef.

I have developed datasets of the carbonate chemistry and sediment maps of the southwest Pacific, which have been widely used by marine ecologists to understand the habitats of marine organisms that live on the seafloor. These datasets have been used to identify the potential distribution of deep marine vulnerable marine ecosystems in the South Pacific. I have also been involved in a New Zealand project CARIM (Coastal Acidification: Rates, Impacts and Mitigation) to determine the variability of pH and carbonate chemistry of the coastal regions. These projects have Maori and regional government stakeholders that will be using this information to develop future strategic management plans.

I am also currently involved in a large project to understand recurrence of large earthquakes on the Hikurangi Subduction Margin, east coast of the New Zealand north island. This project is using a suite of cores from across the margin to look at the frequency of sedimentary gravity flows (turbidites), to determine the occurrence of earthquakes along this margin to develop hazard models for the east coast of the North Island communities and New Zealand government.

Qualifications

  • Doctor of Philosophy, Australian National University

Publications

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Publications

Journal Article