University of New South Wales - BEES Home

SUPERVISOR: PROFESSOR PETER STEINBERG

Co-supervisors: Dr Alistair Poore and Professor Staffan Kjelleberg

EDUCATION

PhD in ecology
University of New South Wales (2006 - present)

B.Sc (Hons) in marine ecology (first class honours)
University of New South Wales (2002)

DOCTORAL RESEARCH

Climate change and emerging disease: bleaching and bacterial infection of a marine macroalga

Recently, the importance of disease as a factor in structuring natural populations and communities has been an increasing focus in ecology. Such diseases often affect important habitat-forming organisms such as corals, seagrasses and macroalgae, and can be mediated by environmental variables including temperature and ultra-violet radiation. Delisea pulchra is a chemically defended red alga that occurs commonly in southern Australia. D. pulchra defends itself from herbivores and bacterial colonisation by producing secondary metabolites called furanones. We have observed a 'bleaching' phenomenon in natural populations of this alga, where affected individuals lose pigment on localised areas of their thalli. Bleaching is more prevalent during summer, when water temperatures are elevated and furanone levels often lowest. Bleached individuals have significantly reduced furanone levels in their tissues, compared to healthy co-occurring individuals and support significantly different surface-associated microbial communities.

Analogous to some instances of coral bleaching, we hypothesized that bleaching in Delisea pulchra is due to a bacterial pathogen. The bacterium Ruegeria strain R11 has been identified on DGGE banding patterns from bleached individuals but not those from healthy individuals. We isolated and cultured this bacterium from D. pulchra, and inoculated D. pulchra individuals in the laboratory. At higher temperatures, the bacterium became virulent and, when plant furanone production was also experimentally inhibited, the bacteria invaded the thallus leading to algal bleaching. We are also investigating whether herbivores facilitate disease infection or transmission. In preliminary field experiments, bleaching was induced in plants that were damaged with a scalpel to simulate herbivory and inoculated with Ruegeria sp. R11.

PREVIOUS RESEARCH

The effects of herbivorous amphipods on macroalgae
Molecular structure and antifouling function of synthesised furanones against common fouling organisms

BROAD RESEARCH INTERESTS

Ecology and evolution of interactions between hosts, pathogens and herbivores
Climate change, multiple stressors and emerging marine disease
Climate change and marine conservation
Co-evolution of plant-herbivore and host-pathogen systems
Ecology and evolution of marine macro/micro-biotic interactions
Marine chemical ecology

COLLABORATIONS (by project)

Susceptibility of diseased and UVR-damaged plants to herbivory and predation (ongoing). Collaborators: Dr Adriana Verges (ECU); Dr Tilmann Harder (UNSW)
Differences in susceptibility to bleaching disease in Delisea pulchra due to genetic variation between individuals and populations (ongoing). Collaborators: Dr Melinda Coleman (UNSW)
The effects of sewage outfalls on survival, reproductive potential, metal contamination and surface associated microbial community of the macroalga Phyllospora comosa (ongoing). Collaborators: Dr Melinda Coleman (UNSW); Dr David Roberts (UNSW); Dr Brendan Kelaher (UTS)

SEE ALSO

Centre for Marine Biofouling
Ecology and Evolution Research Centre

CONTACT DETAILS

Tel: +61 2 9385 2080
Email: alex.campbell@student.unsw.edu.au