Katherina Petrou's Homepage

From the ice to the open ocean: Threats to phytoplankton productivity in Antarctica from a changing climate


Katherina Petrou Current Appointment: PhD Student Contact: Aquatic Photosynthesis Group Department of Environmental Sciences University of Technology, Sydney PO Box 123 Broadway NSW 2000 Australia Office: Building 4, Level 5, Room 66 (City Campus) Phone: 9514 8345 Fax: 9514 4079 Email: Katherina.L.Petrou@student.uts.edu.au Project Summary: Ephemeral sea-ice is a defining structural feature of Polar ecosystems and due to its high albedo (reflectivity) plays an essential role in the global energy balance. Antarctica is considered one of the most vulnerable ecosystems in the world with regard to global warming impacts and is commonly regarded as a sentinel for climate change. Predicted environmental changes that will impact most on the Antarctic marine ecosystem include increases in sea surface temperatures, altered ocean chemistry through increased CO₂ and modified ocean circulation patterns (Knox 1994). Antarctic microalgae live and function in one of the most severe and inhospitable environments on the planet. Sub-zero temperatures and limited light availability, makes life for aquatic microalgae extremely challenging. While sea-ice algae are able to cope with strong temperature, salinity and light gradients and are well-adapted to survive extreme conditions and environmental variability (experienced both spatially and temporally), understanding the physiological constraints of these organisms will enhance our knowledge as to how far climate change will challenge their physiological limits. My project examines the processes of light acclimation and photoprotection of Antarctic microalgae under various physical and chemical stresses that may result from climate change, comparing photokinetic responses of microalgae from the sea-ice, meltwater and open ocean regions. Specifically, it is aimed at understanding the impacts of increased atmospheric CO₂ concentrations (and subsequent ocean acidification) on the health and productivity of microalgae from the Antarctic marine ecosystem under different nutrient and light regimes. My project will contribute valuable data about Antarctic and Southern Ocean microalgal productivity and the photophysiology that these microalgae employ as part of their adaptive strategy to changing climate. It will provide a better understanding of the magnitude and susceptibility of the Antarctic marine ecosystem from the threats of climate change and as a result, provide information about the possible impacts that the altered functioning of the Antarctic marine ecosystem may have on the global energy balance, thermohaline circulation and biogeochemical cycling. In addition, it will contribute information about changes to phytoplankton species abundance, distribution and community composition that may occur as a result of climate change. This has the potential to impact the entire trophic web and commercial fisheries. Furthermore, the findings obtained from this study will lead to improved predictive capabilities regarding the response of phytoplankton to global climate change and will allow the development and validation of photosynthesis models as well as increased understanding of cellular carbon fluxes of the marine environment. The principle instruments that will be used during my project will be Pulse Amplitude Modulated (PAM) fluorometers and a dual-modulation fluorometer (Photon System Instruments), as well as a Membrane-inlet Mass-spectrometer (MIMS) system and oxygen micro-optodes. Supervisors: Assoc. Prof. Peter Ralph (UTS) Dr. Martina Doblin (UTS) Dr. Christel Hassler (CSIRO, Hobart) Scholarships & Awards: 2006 *Australian Post Graduate Award* – supporting my current PhD project at UTS *Dean’s Merit List Award (UTS)* - for Academic Excellence 2005 *Dean’s Merit List Award (UTS)* – for Academic Excellence 2002 *Dean’s Merit List Award (UTS)* – for Academic Excellence Media Releases/interviews: University of Technology, Sydney – Undergraduate Guide, 2008. Radio Interview - 18 December 2007 2SER Conference Presentations: Petrou, K. Shelly, K. Hassler, C. Schoemann, V. Doblin, M. Ralph, P (2007). Ocean productivity in a changing world ~ Iron-limitation of Southern Ocean Phytoplankton and implications for Antarctic meltwater productivity. Australian Marine Science Association, Melbourne, Australia. Publications: Petrou K, Doblin M, Smith R, Ralph P, Shelly K, Beardall J. (In Press). Interacting energy pathways during a Nutrient-Induced Fluorescence Transient (NIFT) in phosphorus-limited Dunaliella tertiolecta. Journal of Phycology. Teaching: Tutor for Contemporary Environmental Issues (2007) Collaborative Work: *Cellular ATP concentrations in P-limited Dunaliella tertiolecta* during a NIFT response Dr. Ross Lilley (Research Associate UTS, formerly Wollongong University) Investigations into the NIFT mechanism Prof. John Beardall & Dr. Kirsten Shelley (Monash University) Impacts of high light under Iron-limitation on Southern Ocean phytoplankton Dr. Veronique Schoemann (Université Libre de Bruxelles) & Dr. Christel Hassler (CSIRO, Hobart) Impacts of CO₂ on phytoplankton communities from the Southern Ocean** Dr. Simon Wright et al. (Australian Antarctic Division)* Contract Work: 2007 Eraring Power & HLA Consultants “Thermal stress in the seagrass Zostera capricorni.”