Understanding disease in marine seaweeds: from molecular mechanisms to ecological consequences

In the last ten years the effects of disease on natural marine communities have become increasingly apparent, with organisms as diverse as seagrasses, seals and corals suffering from major disease-related die-offs. Human impacts via pollution or climate change are thought to have played a major role in the impact of these diseases. Recent evidence indicates that a bacterial disease causes “bleaching” of the red seaweed Delisea pulchra.  Seaweeds are the “trees” of temperate rocky reefs, creating the biological habitat in which many other marine organisms flourish.  In the same way that the potential loss of coral reefs from climate change would have dramatic, system-wide effects in tropical waters, the loss of kelp from temperate shores would be devastating to the functioning and biodiversity of these systems.

As part of the Integrated Marine Observing System (IMOS), we are combining cutting-edge robotics technology with field ecology and molecular microbiology to gain insights into the distribution and condition of kelp communities around Australia in order to understand how they are responding to environmental change. We are also investigating broadly the interplay between bacterial virulence and environmental factors, such as temperature, light and nutrients, and natural bacterial inhibitors to understand the epidemiology and impact of disease on the ecology of kelps and other seaweeds. Here we are using genomic and gene expression analysis together with site-directed mutagenesis to identify and characterise potential virulence mechanisms in model macroalgal disease systems. We also perform environmental surveys to assessing prevalence of pathogens and determine how the natural microbial community shifts under disease conditions. For more information contact Prof. Peter SteinbergDr Suhelen Egan, Prof. Torsten ThomasDr Alex Campbell or Dr Ezequiel Marzinelli.

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