1

People and ecosystems

Understanding of the links between coral reef ecosystems, the goods and services they provide to people, and the wellbeing of human societies.

2

Ecosystem dynamics: past, present and future

Examining the multi-scale dynamics of reefs, from population dynamics to macroevolution

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Responding to a changing world

Advancing the fundamental understanding of the key processes underpinning reef resilience.

Coral Bleaching

Coral Bleaching

Coral Reef Studies

ARC Centre of Excellence for Coral Reef Studies
James Cook University Townsville
Queensland 4811 Australia

Phone: 61 7 4781 4000
Email: info@coralcoe.org.au

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Private: Reef sharks prefer bite-size meals

23
Feb 2016

Sharks have a reputation for having voracious appetites, but a new study shows that most coral reef sharks eat prey that are smaller than a cheeseburger.

Lead author, Dr Ashley Frisch said that after pumping a shark’s stomach to identify the contents of its last meal, the most common thing to find was in fact, nothing. Researchers from James Cook University’s ARC Centre of Excellence for Coral Reef Studies examined stomach contents of reef sharks and conducted chemical analyses of shark body tissue to find out what they had been eating.

“We were surprised to find a broad range of small prey items such as fish, molluscs, sea snakes, crabs and more often than not, nothing at all”.

“These results suggest that reef sharks eat small meals infrequently and opportunistically,” Dr Frisch said.

To understand what the sharks were eating over longer periods, the researchers analysed shark body tissue.

“Although black-tip, white-tip and grey reef sharks have long been thought of as top predators, we found that the chemical structure of the sharks’ body tissue actually matched closely with that of large reef fishes such as groupers, snappers and emperors,” Dr Frisch said.

“This result tells us that reef sharks and large fishes have a similar diet, but they don’t eat each other. So rather than eating big fish, reef sharks are eating like big fish.”

Understanding ‘who eats who’ on coral reefs is important in helping scientists better predict how changes in one population impact another.

Co-author of the study, Dr. Justin Rizzari, said the new research changes how scientists think about food webs on coral reefs and acts as a reminder that large, conspicuous predators are not always at the top of the food chain.

“We now know that reef sharks are an important link in the food chain, but they are not the last link in the food chain. In most cases, the top predators are tiger sharks, hammerhead sharks, or people,” Dr Rizzari said.

“Coral reef ecosystems are very complex. The more we look, the more we realise that each and every species plays an important role. Sharks are no exception. They help to keep coral reefs healthy and should be managed wisely.”

With coral reefs around the world in decline and humans killing an estimated 100 million sharks every year, understanding the exact role sharks play in coral reef ecosystems is more urgent now than ever.

The article entitled “Reassessing the trophic role of reef sharks as apex predators on coral reefs” was recently published by the journal Coral Reefs.

Paper:
Ashley J. Frisch, Matthew Ireland, Justin R. Rizzari, Oona M. Lönnstedt, Katalin A. Magnenat, Christopher E. Mirbach, Jean-Paul A. Hobbs (2016) Reassessing the trophic role of reef sharks as apex predators on coral reefs. Coral Reefs.

Images:
http://bit.ly/1TrS9sj
(Images must carry credits and captions as listed in Dropbox folder)

Contacts:
Dr Ashley Frisch (preferred)
Tel: +61 7 4780 4661
Email:  ashley.frisch@jcu.edu.au

Justin R. Rizzari
Tel: +61 4 5055 1087
Email: justin.rizzari@my.jcu.edu.au

Reef sharks, like this black-tip shark, typically eat small fishes, molluscs and crustaceans. Black-tip sharks, in turn, are eaten by larger sharks such as tiger and hammerhead sharks. Photo by Simon Gingins.
Reef sharks, like this black-tip shark, typically eat small fishes, molluscs and crustaceans. Black-tip sharks, in turn, are eaten by larger sharks such as tiger and hammerhead sharks. Photo by Simon Gingins.

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Coral Reef Studies

ARC Centre of Excellence for Coral Reef Studies
James Cook University Townsville
Queensland 4811 Australia

Phone: 61 7 4781 4000
Email: info@coralcoe.org.au