Dr Alexandra Campbell
Research Associate
Field of Research: 
Marine ecology, environmental change, disease, species interactions
Contact details:
+61 2 9385 8723

Room 501H
Biological Sciences Building (D26)
UNSW, Kensington 2052

Research & Current Projects 

Research Interests

My research focuses on interactions between habitat-forming organisms in marine ecosystems and the things that eat, grow on or infect them. I’m particularly interested in how changing environmental conditions alter these interactions and what ecological and biological consequences such alterations have at individual, community and ecosystem scales. A recent focus of my research has been climate-mediated diseases, which are increasing with frequency and severity in diverse habitats globally. Although I’m interested in marine habitat formers generally (including corals and seagrasses), most of my research to date has involved seaweeds. These marine macrophytes form underwater forests and are the basis of coastal, temperate marine ecosystems, supporting other organisms from the ‘bottom-up’ by providing food and shelter. Seaweeds are showing evidence of global decline and this could have potential far-reaching ecological and socio-economic implications. Through my research, I aim to address this problem by trying to both understand and describe the mechanistic causes of declines and develop solutions for their prevention and amelioration.


Current Projects


Marine organisms live in a ‘microbial soup’ – in persistent contact and interaction with microorganisms, which are abundant on, within and surrounding their tissues. Environmental changes can interfere with the intimate and often fundamental interactions between microorganisms and their ‘hosts’, often with dramatic consequences. Indeed, as global climates change, the incidence and severity of microbial diseases affecting natural populations of diverse marine organisms also appear to be rising. One hypothesis for this apparent change is that increasingly stressful conditions lead to more susceptible hosts, whilst simultaneously enhancing pathogen abundance and virulence. The ecological impacts of diseases are likely to be more severe when they affect habitat-forming organisms such as corals and seaweeds, as any impacts could cascade throughout entire communities. I am broadly interested in how rising ocean temperatures and other local stressors affect disease dynamics in marine habitat-formers and the ecosystems they support. My main collaborators on this project are Professor Peter Steinberg, Dr Ezequiel Marzinelli, Adriana Verges and Torsten Thomas.


Anthropogenic degradation of natural habitats is a major cause of loss of biodiversity and ecosystem function. Programs aimed at restoring habitat forming species mostly target terrestrial ecosystems, but loss of marine habitat forming species such as corals in the tropics and seaweeds (macroalgae) in temperate waters is now a global issue. Restoration efforts of marine habitat formers are in their infancy, particularly for seaweeds; thus understanding the ecological processes that allow for their successful reestablishment and that of associated biodiversity is crucial for management and conservation.

'Crayweed' (Phyllospora comosa) is a key habitat-forming macroalga on rocky reefs in NSW that provides habitat and food to commercial species and supports biodiversity. Crayweed disappeared from the Sydney coast during the last 40 years, probably related to heavy sewage outfall discharges during 1970’s - 80’s and despite significant improvements in water-quality, crayweed has not re-established. By conducting transplant experiments, colleagues (Dr Ezequiel Marzinelli, Dr Adriana Verges and Professor Peter Steinberg) and I have shown that at small scales, crayweed can survive and successfully reproduce on reefs from which it has been missing for decades.


Dramatic, system wide changes in ecosystems are known as phase shifts, which typically result in less diverse or less productive communities. In coastal marine systems, there are two well known phase shifts; the shift from coral to seaweed dominated systems in the tropics, and from kelps to urchin barrens in temperate areas. This work has investigated a third, novel phase shift in coastal marine communities brought about by the intrusion of tropical herbivorous fishes into temperate kelp forests and has been led by Dr Adriana Vergès at UNSW. At this stage, we have focused on a temperate-tropical transition zone in eastern Australia (also a global warming ‘hot-spot’) and conducted surveys of kelp communities and herbivore populations on various environmental gradients. Additionally, we have conducted feeding experiments to assess the impact of tropical herbivorous fish and urchins on temperate kelp beds. Although work is ongoing, our initial results suggests that tropical herbivores are likely to have an important impact on temperate algal forests as they follow their thermal envelopes poleward and potentially, to greater depths.


Although there are clear, global patterns of decline on coral reefs, there is considerable debate about what will happen to reefs in the future. The most pessimistic predictions point towards the complete loss of functional reefs within a few decades, while others predict that reefs will change in terms of community structure but not disappear. Correctly predicting the future of coral reefs requires long-term studies of reefs under a range of environmental conditions, however there are still relatively few long-term studies of coral reefs and the majority of these come from either the Caribbean or the Great Barrier Reef.

This work has been done in collaboration with Dr James Guest and colleagues at Nanyang Technical University in Singapore, David Feary at UTS and Adriana Verges and Peter Steinberg at UNSW and has involved the examination of a long-term (27 years) study of the benthic community structure on coral reefs at two depths around Singapore, an equatorial, urbanized and heavily impacted place at the southern tip of peninsular Malaysia. In addition we assessed the contemporary role of herbivory on these reefs using both direct and indirect assay techniques. Remarkably, coral cover and diversity have varied very little at the shallow sites since the mid 1980s. While coral cover at the deeper site has declined significantly there was no marked increase in cover of fleshy seaweeds, which is in opposition to many well-accepted models of coral-algal interactions on coral reefs.


In the Media

Alex recently participated in Randwick Council’s ‘Coastal Activities’ program: Coastal activity program 2013

Alex was a panellist at a recent Ultimo Science Week event:

Alex recently published an article in ‘Australian Quarterly’:

Alex was a panellist at the recent ‘SIMS at 7’ event ‘Women in Marine Science’:

Alex was a panellist at the recent ‘Northside Forum’, ‘Plenty of fish in the Sea?’:


See also

Alex's Google Scholar Profile

Alex's LinkedIn Profile

Alex's Research Gate Profile



Research Students 


Tamsin Peters (PhD candidate; co-supervised with Professor Peter Steinberg and Dr Melinda Coleman) – Environmental stress and disease in the habitat-forming fucoid Phyllospora comosa.

Galaxy Qiu (PhD candidate; co-supervised with Professor Peter Steinberg, Assoc. Prof. Torsten Thomas and Dr Tim Lachnit) – Disease, microbial pathogens and genes: molecular interactions among kelp, bacteria and viruses under different environmental conditions.

Mat Skye (Honours candidate; co-supervised with Dr Adriana Verges and Dr Ezequiel Marzinelli) – Kelp declines in a tropical-temperate transition zone and the role of herbivory



Martin Leong (Honours 1 graduate 2012) – Marine invertebrate communities and the restoration of missing underwater forests in Sydney

Tamsin Peters (Honours 1 graduate 2010) – Phyllospora comosa: distribution and disease

Melissa Vargas (Honours graduate 2010) – Pollution and disease: microbial communities associated with a declining fucoid and the influence of outfalls

Shaun Nielsen (Honours 1 graduate, 2008) – Nutrients, chemical defences and bleaching in a chemically defended seaweed



MSCI0501  The Marine Environment (Course Convenor)

BIOS2031  Biology of Invertebrates (Lecturer)

BIOS3091  Marine and Aquatic Ecology (Lecturer)



Campbell, A. H., Vergés, A. & Steinberg, P. D. (2013) Demographic consequences of disease in a habitat-forming seaweed and impacts on interactions between natural enemies. Ecology, (in press).  Impact factor 4.78.

Campbell, A. H., Marzinelli, E. M.*, Vergés, A., Coleman, M. A. and Steinberg, P. D. (2013) Towards restoration of missing underwater forests. PLoS ONE (in review). *denotes joint first authorship. Impact factor 3.74.

Marzinelli, E. M., Campbell, A. H.* Vergés, A., Coleman, M. A., Kelaher, B. P. & Steinberg, P. D. (2013) Restoring seaweeds: does the declining fucoid Phyllospora comosa support different biodiversity than other habitats?. Journal of Applied Phycology (accepted). *denotes joint first authorship. Impact factor 2.33

Campbell, A. H., Vergés, A., Harder, T. & Steinberg, P. D. (2012) Causes and ecological consequences of a climate-mediated disease. In: Lunney and Hutchings (Eds) ‘Wildlife and climate change: toward robust conservation strategies for Australian fauna’. Royal Zoological Society of New South Wales, Mosman, NSW, Australia. National press coverage.

Poore, A. G. B., Campbell, A. H., Coleman, R. A., Edgar, G. J., Jormalainen, V., Reynolds, P. L., Sotka, E, E., Stachowicz, J. J., Taylor, R. B., Vanderklift, M. A. & Duffy, E. J. (2012). Global patterns in the impact of marine herbivores on benthic primary producers. Ecology Letters 15(8), 912-922. Impact factor 17.6; ISI Journal Citation Reports Ranking 2011: 1/134 (Ecology); Cited 12 times; International press coverage

Harder, T., Campbell, A. H., Egan, S. and Steinberg, P. D. (2012). Chemical mediation of ternary interactions between marine holobionts and their environment as exemplified by the red alga Delisea pulchra. Journal of Chemical Ecology 38(5), 442- 450. Impact factor 2.66; Cited 4 times.

Wernberg, T., Smale, D. A., Vergès, A., Campbell, A. H., Russel, B. D., Coleman, M. A., Ling, S. D., Steinberg, P. D., Johnson, C. R., Kendrick, G. A. & Connell, S. D. (2012). Macroalgae and temperate rocky reefs. In: Poloczanska, Hobday and Richardson (Eds) Report Card of Marine Climate Change in Australia, detailed scientific assessment, NCCARF publication, p1-23.

Campbell, A. H., Nielsen, S., Harder, T., Kjelleberg, S. & Steinberg, P. D. (2011) Climate change and disease: bleaching in a chemically defended seaweed Global Change Biology, 17(9): 2958-2970. Impact factor 6.9 ISI Journal Citation Reports Ranking 2011: 1/37 (Biodiversity Conservation); Cited 17 times; International press coverage.

Steinberg, P. D., Rice, S. A., Campbell, A. H., McDougal, D. & Harder, T. (2011). Interfaces between bacterial and eukaryotic “neuroecology” Integrative and Comparative Biology, 51(5), 794-806. Impact factor 2.45. ISI Journal Citation Report Ranking 2011: 15/146 (Zoology); Cited 3 times.

Wernberg, T., Russell, B. D., Moore, P. J, Ling, S. D., Smale, D. A., Campbell, A. H., Coleman, M. A., Steinberg, P. D., Kendrick, G. A., Connell, S. D. (2011). Impacts of climate change in a global hotspot for temperate marine biodiversity and ocean warming Journal of Experimental Marine Biology and Ecology 400(1-2): 7-16. Impact factor 2.4; Invited review; most downloaded paper from JEMBE since publication and now an ‘ISI highly cited paper in Plant & Animal Science’; Cited 40 times; National Press coverage.

Case, R. J., Longford, S., Campbell, A. H., Low, A., Tujula, N., Steinberg, P. D. & Kjelleberg, S. (2011) Temperature induced bacterial virulence and bleaching disease in a chemically-defended marine macroalga Environmental Microbiology 13(2): 529- 537. Impact factor 5.84. ISI Journal Citation Report Ranking 2011: 14/114 (Microbiology); Cited 19 times; Cover article.

Poore, A. G. B., Campbell, A. H., and Steinberg, P. D. (2009) Natural densities of mesograzers fail to limit growth of macroalgae or their epiphytes in a temperate algal bed Journal of Ecology 97: 164-175. Impact factor 5.04; ISI Journal Citation Ranking Report 2011: 17/134 (Ecology). Article recommended for F1000; Cited 17 times.

Wernberg, T., Campbell, A. H., Coleman, M. A., Connell, S. D., Kendrick, G. A., Moore, P. J., Russell, B. D., Smale, D. A., Steinberg, P. D. (2009) Marine Climate Change in Australia, Impacts and Adaptation Report Card (2009): Macroalgae and temperate rocky reefs. NCCARF publication. Featured widely in the media + nominated for a prestigious Eureka Award.