Science at the Shine Dome 2010

Early-career researcher awards

Thursday, 6 May 2010

2010 Dorothy Hill Award

Dr Nicole Webster
Australian Institute of Marine Science

Nicole Webster obtained a PhD from James Cook University in 2001; her thesis investigated the microbial ecology of a Great Barrier Reef sponge, focusing on the stability of the symbiotic associations over different latitudinal and stress gradients. Her postdoctoral research between 2001 and 2005 was conducted at the University of Canterbury and Gateway Antarctica and focused on utilising microbial communities as sensitive indicators for human-induced stress in the Antarctic marine environment. This project was multifaceted and included aspects of symbiosis research, biofilm analysis, invertebrate recruitment and assessing heavy metal/hydrocarbon contamination of the environment. For the past five years Nicole has been employed at the Australian Institute of Marine Science where her research has focused on the impact of environmental stress using sponge microbial symbiosis as a sensitive marine model.

Marine microbes and symbiosis – sentinels for marine ecosystem health

Although out of sight, microorganisms constitute the vast majority of marine biomass. Microbes are ideal indicators for alerting us to stress in the marine system as they respond very rapidly to small changes in environmental conditions. They also have a wide range of critical functions in the marine environment – from carbon cycling to reef recruitment processes, disease, and symbiotic associations. Most marine invertebrates, from worms to corals, rely on microbial symbionts living within their tissues. Marine sponges, for instance play host to extraordinarily dense and diverse microbial communities. We have revealed that a single sponge species can host up to 3000 bacterial genera, comprising up to 40 per cent of sponge volume. These microbes contribute to essential aspects of sponge biology, including carbon and nitrogen nutrition and chemical defence.

Our recent research has explored the use of stable sponge-microbial partnerships as sensitive indicators for sub-lethal stress in the reef ecosystem. We have found dramatic shifts in sponge-microbial associations at elevated seawater temperature between 31ºC and 32ºC, identical to temperatures known to cause coral bleaching. Under these conditions the symbiotic partnerships in sponges also break down and the microbial communities become dominated by pathogens found associated with coral disease. This research reveals the sensitivity of diverse microbial communities within sponges to a changing climate and the need to broaden our assessment of reef vulnerability to include a wide range of key microbial communities.