How to collect a parasite: researching a covert eco-system

Written by: Christine Robertson, Corporate Communication Officer

If you have ever been snorkelling or diving on the Great Barrier Reef, you would be astounded by the wondrous beauty of the intricate eco-system that happens under the sea.

This reef eco-system comprises corals and an abundance of marine life, but delve down another layer and there is a covert eco-system happening right before your very eyes – it’s just you cannot see it.

It is this hidden eco-system that Dr Robert Adlard, Head Marine Environments and Senior Curator – Parasites is fascinated with.

Throughout his career, Dr Adlard has discovered more than 130 new species of parasites – but how does one go about discovering these hidden species?

Heading under water with a team of scientists, the process is quite a lengthy one, particularly when you are working with tiny marine life such as small fish.

While bigger fish can be caught by traditional methods, capturing a small fish requires a little bit of creativity.

Dr Adlard anaesthetising small fish
Dr Robert Adlard anaesthetising small fish in the reef.


Spears are used to catch larger fish.
Spears are used to catch larger fish.

Dr Adlard and his team take bottles of the natural anaesthetic clove-oil (you may have used it for tooth-ache when you were kids…) and essentially ‘knock out’ the fish underwater to take back to the lab to euthanise humanely.

From there, the real work begins in searching for the parasitic life within. The team will dissect, investigate muscles, brain tissue and other areas of the fish to try to identify tiny spores, which under magnification can appear like little flowers.

Material is then preserved for further DNA extraction and investigation. Once that is complete analysis begins against other known species and estimates on the host range and distribution are calculated.

Even if a new species is identified, the work does not stop there – drill down and Dr Adlard needs to find out other details such as how transmission occurs between fish, what is the commercial significance if any of these parasites and what are the effects on the fish.

Dr Robert Adlard and his team collecting specimens off Lizard Island on the Great Barrier Reef.
Dr Robert Adlard and his team collecting specimens off Lizard Island on the Great Barrier Reef.

It’s a lengthy cycle that sees projects extend for years, sometimes more than a decade. Parasites cost the economy billions of dollars each year, yet they don’t automatically spring to the top of mind when you think of dangerous species. Yet by definition, a parasite is an organism that lives on or in an organism of another species known as the host, from the body of which it obtains nutrient. So there is always a cost to the host. And we are faced with parasites within our day to day lives, without maybe even thinking about it.

With around 100,000 parasite specimens in our Collection, the Queensland Museum has the fifth largest collection of parasites in the world.

Dr Robert Adlard and his team ready to take their specimens back to the lab for further research.