Dept. Biological Sciences, Macquarie University , Sydney , NSW 2109.

Phone: (02) 9850 9686

Fax: (02) 9850 8245

dbutt@bio.mq.edu.au

 

The project I am involved in is working to identify some of the factors that affect immune activity in Sydney rock oysters, leaving them susceptible to infection from the protozoan, Marteilia sydneyi , the causative agent of QX disease. QX disease has most recently devastated oyster stocks in the Hawkesbury River , north of Sydney , and threatens to spread to other estuaries.

Work to date has indicated that increased stress on oyster populations from various environmental sources, such as salinity, pollutants and even starvation, can affect the immune competency of oysters. This in turn makes oysters more susceptible to opportunistic QX infection. Some of the immunological parameters that I have monitored include lysosome activity, general antimicrobial activity, total protein levels and phenoloxidase activity of oyster haemolymph.

The project also involves continuing research into potential markers for disease resistance in selectively bred oyster lines. DPI fisheries have been involved in breeding oysters naturally selected for QX disease resistance for a number of years and it is now important to assess genetically the specific factors involved in this resistance. This will aid both our understanding of the process of disease resistance in these animals, as well as improving future selection of disease resistant breeding lines.

I am also going to extend my research on the impact of environmental stressors to determine if they have a similar effect on another marine invertebrate, the Blacklip abalone, Haliotus rubra . This species has recently been afflicted by major outbreaks of the parasite, Perkinsus olseni , which is threatening to destroy populations in NSW waters. It will be interesting to assess whether immune inhibition, associated with environmental stress may have had a hand in the increased prevalence of this disease.