Carbonate platforms, coral reef frameworks, and modern shallow reef environments such as lagoons, reef flats and coral sand cays and carbonate sand islands and beaches, that are formed from neritic carbonate sediments, don’t only play a central role in the global carbon cycle, but they also provide a myriad of ecosystem services, such as habitats for marine life, fishing, tourism, and human habitation (Hoegh-Guldberg 2007; Storlazzi et al. 2018). Sediments represent the storage of detrital carbonate material (eroded from the solid reef) and the skeletal remains of other benthic producers that have accumulated over thousands of years (Smith et al., 2009). These sediments can comprise a very large proportion of the calcium carbonate in carbonate ecosystems, representing up to 95% of the aerial benthic coverage in some coral reefs ecosystems (Gattuso et al. 1998), and a large proportion the sediment produced is transported off of the source reef ecosystem to local shelf environments (Ryan et al. 2001). However, for coral reef structures, and other carbonate ecosystems, to be in a state of net accumulation and vertical growth, the net production of carbonate (and external sediment supply) must exceed its loss through physical erosion and dissolution (Eyre et al., 2014). For this state of positive accretion to occur, net ecosystem calcification (NEC), or the chemical measure of the net production of carbonate material of an ecosystem, must be positive. As such, understanding the factors controlling net ecosystem calcification and associated carbonate sediment dissolution is important for understanding the future of coral reef ecosystems (Eyre et al. 2018).
This Australian Research Council Discovery project will look at the of role of advection, anthropogenic organic matter enrichment, ocean acidification and warming on net ecosystem calcification and carbonate sediment dissolution across the Great Barrier Reef, Australia. We are currently seeking two PhD students for 1) field measurements of carbonate sediment dissolution, and 2) experimental studies of carbonate sediment dissolution. Both PhD students will be based at Southern Cross University in Australia and will work as part of a multidisciplinary team of post-graduate, post-doctoral and senior biogeochemists from Southern Cross University, Georgia Southern University (USA) and Max Planck Institute (Germany).
PhD Project 1. Field measurements of carbonate sediment dissolution
This project will quantify lagoonal and shallow shelf carbonate sediment dissolution rates across an aragonite saturation gradient in the Great Barrier Reef at current and future ocean acidification conditions. This project will use a combination of different techniques such as advective benthic chambers and electronic field equipment
PhD Project 2. Experimental studies of carbonate sediment dissolution
The project will use flumes and mesocosm to (i) establish functional relationships between flow, light, temperature, carbonate chemistry, organic matter loading carbonate mineralogy and carbonate sediment dissolution and (ii) thresholds for when sediments change from net precipitating/calcifying to net dissolving.
Selection criteria: Applicants for both projects must have an Honours (1st, 2A class) or Master’s degree, undertaken in English, in a related field such as biogeochemistry, environmental chemistry, or closely related. The project will involve extended periods of intensive field work in remote areas, laboratory work and data analysis. Experience working from boats and island research stations, scientific diver qualifications (or be willing to obtain before the position commences), experience using automated electronic field instrumentation (e.g. SeapHOx), experience undertaking high precision DIC and alkalinity analysis, experience with flumes and mesocosms (PhD 2), and experience with the analysis of large data sets using R, Matlab or Python, will be viewed favourably.
The candidates will be based in the Centre for Coastal Biogeochemistry (https://twitter.com/biogeochemSCU, https://www.scu.edu.au/centre-for-coastal-biogeochemistry/) at Southern Cross University (Australia). The Centre for Coastal Biogeochemistry has a world-class research group including a number of post-graduate, post-doctoral and senior researchers working in similar areas, providing an outstanding environment for intellectual stimulation and opportunities for exchange of ideas. The Centre has world-class infrastructure including access to an extensive stable isotope facility with full technical support, a membrane inlet mass spectrometer (MIMS), well equipped inorganic and organic chemistry laboratories, and a range of field equipment including benthic chambers, data sondes, and Picarro Cavity Ring-down Spectrometers (see http://scu.edu.au/coastal-biogeochemistry). Southern Cross University received the highest rank of 5.0 (well above world standard) in geochemistry in all the national research excellence assessments.
Scholarships provide a tax-free annual stipend of $29,863 for 3 years and 3 months, and tuition fees will be exempt. Interested applicants should send a CV and short (< 1 page) statement highlighting (1) which project they are interested in (2) their research background and interests, and addressing each of the selection criteria above, to Prof Bradley Eyre (firstname.lastname@example.org). Only short-listed applicants will be notified. Closing date for applications is April 9, 2023. Preferred starting date is mid to late 2023 (negotiable).
Southern Cross University is based in Lismore, northern NSW, Australia (near Byron Bay). The region is a great place to live with a perfect sub-tropical climate (not too hot, not too cold), some the best beaches and surfing in the world, plus great fishing, scuba diving and wilderness areas.