Building up a better picture of jellyfish parasites



Hydromedusa.
Image: Gary Cranitch.

 

Thursday 19 February 2009
 
A TRIP to Lizard Island one year ago helped Jo Browne narrow the focus of her PhD studies.
 
This time around she's hoping to expand her knowledge in her chosen field.
 
Jo is doing her PhD on the parasites of gelatinous zooplankton in Eastern Australia, through Griffith University, Australian Rivers Institute (Coast and Estuaries) and Museum Victoria.
 
Last year she decided to focus on the parasites, which have not been studied in any detail on jellyfish.
 
Jo said she hoped her work might fit into the larger base of knowledge about parasites, known as digeneans, in fish.
 
"Jellyfish are just one part of the life cycle of the digeneans," she said.
 
They start on a mollusc, can move to a jellyfish as they grow, and then mature in fish.
 
A number of studies on fish parasites have been completed, but the role that jellyfish play in their development is still relatively untested.
 
With jellyfish numbers dramatically increasing worldwide, Jo's work could soon become very important.


Digenean under a microscope.
Image: Jo Browne

 

With that in mind, she is working on establishing two specific things:
  • A basic idea of how many species of parasites there are; and
  • Getting enough genetic material to match parasites in jellyfish to their adult forms in fish.
Last year Jo found the digeneans on cassiopea, the upside down jellyfish, while this year she has seen them on comb jellies (ctenophores) and jellyfish known as hydromedusas.
 
Given that a recent study estimated there were about 20,000 parasite species on the Southern Great Barrier Reef (in just 1,000 fish species), Jo has a lot of work ahead of her.
 
"Where fish are being removed, jellyfish are taking over their place," she said.
 
"My work could be an important factor in understanding what's happening."