Research examines how fish make their own sunscreens

A University of Queensland researcher is examining how coral reef fish obtain their own sunscreens.

Dr Lexa Grutter, from the School of Life Sciences, is using advanced technology, including a newly developed underwater hyperspectral UV-sensitive camera system, to visualise the UV damage on cleaner-fish.

These controversial fish known as Labroides dimidiatus are well known to biologists and tourists on the Great Barrier Reef. They peck at the bodies of other fish to remove parasites.

“This study is significant because sunscreen compounds in fishes were only recently discovered in the mucus of coral reef fishes and appear to protect fish from UV damage,” Dr Grutter said.

Dr Grutter has received $70,000 as one of 10 recipients of the 2004 UQ Foundation Research Excellence Awards for early career researchers, valued in total at $655,000.

The annual awards, now in their sixth year, recognise outstanding performance and leadership potential, and this year form part of the third annual UQ Research Week from September 22–26.

Every day, corals and fishes in the shallow waters of the Great barrier Reef are exposed to more than thirty times the ultra-violet radiation levels needed to cause human sunburn.

To cope with this intense radiation, many coral reef organisms sequester sunscreen compounds including mycosporine-like amino acids (MAAs).

Dr Grutter said because fishes, like animals, could not synthesise MMA’s they must obtain them from their diet.

“Because cleaner-fish eat a variety of food, including known sources of MAAs, we can investigate how the different parts of their diet contribute to their MAAs,” she said.

However, she said little was known about the source of these compounds.

“We recently found that cleaner-fish have a ‘super’ sunscreen in their mucus as it absorbs a broader range of UV and more UV than the mucus of other fishes,” she said.

“The source of these sunscreens is unknown but could come from the fish mucus they ingest.”

The cleaner-fish system has been extensively studied by Dr Grutter with her research producing the first ever results to support the idea that interactions between cleaner-fish and their clients are mutually beneficial.

More recently she discovered that cleaner-fish use a peculiar yet effective conflict resolution technique, swimming in an oscillating fashion, known as “tactile dancing”.

In fish cleaning interactions, cleaner-fish eat parasites from other fish, often entering the client’s mouth without being cheated and eaten.

Through her observations Dr Grutter was able to show that tactile dancing may function as a pre-conflict management strategy, varying according to client hunger level and enabling cleaner-fish to avoid conflict with potentially dangerous clients.

Dr Grutter joined UQ in 1996. She held an Australian Research Council (ARC) Postdoctoral Fellowship from 19997 to 1999 and currently holds and ARC Australian Research Fellowship. In 2005 she will take up a senior lectureship within UQ’s School of Life Sciences.

Media: For more information contact Dr Grutter (telephone 07 3365 7386, email: a.grutter@uq.edu.au) or Chris Saxby at UQ Communications (telephone 07 3365 2479, email: c.saxby@uq.edu.au). Videos and still photos are available at www.uq.edu.au/news/researchweek