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Pillaging marine life could mean changing ecosystems

Marine scientist Dr Elizabeth Madin by Robert Button

Marine scientist Dr Elizabeth

UTS research into human impacts on the health and well being of marine ecosystems has been boosted with the arrival of scientist Dr Elizabeth Madin from University of California Santa Barbara (UCSB).

Dr Madin has been influential in raising awareness of the dramatic alteration of coral reef ecosystems in the Pacific Ocean due to commercial fishing, which reduces the number of reef predators and affects the behaviour of their prey.

In a pair of studies recently published in two leading US ecology journals, Dr Madin and colleagues from UCSB and Sydney's Macquarie University reported that when hunted by large predators, such as sharks and snapper, small fish hide and move around less. When predator numbers are seriously reduced, their prey move greater distances, take more risks, and change feeding behaviours. These behavioural responses in prey species also drive significant changes in the balance of ecosystems.

Dr Madin and her colleagues studied coral reefs of the central Pacific Ocean's Line Islands, a small equatorial archipelago thousands of miles from the nearest landmass. Predators had been heavily fished near some islands and never fished near others. Dr Madin said they were able to see first-hand how fishing had decimated populations of sharks and other predators.

Carcharhinus melanopterus

Carcharhinus melanopterus

"By removing predators and changing the grazing behaviour of small fish, there were dramatic changes in the seaweed patterns on coral reefs, giving the reefs a new look," Dr Madin said.

"Seaweed is important because lush areas of seaweed inhibit the settling and growth of coral – the critically important engineers of the reef. By changing where seaweed grows, fishing may be limiting where coral can grow."

Previously with UCSB's Department of Ecology, Evolution & Marine Biology, and having earlier completed two Fulbright Fellowships in Australia, Dr Madin is now a US National Science Foundation International Postdoctoral Fellow with the UTS Faculty of Science.

She said Australia offered the perfect environmental gradient, from tropical through to temperate, to conduct research into the impact of fishing on a variety of marine ecosystems. "It is important that we understand how the impacts of fishing can cascade to affect whole ecosystems, not just on coral reefs but also a much wider range of potentially vulnerable marine ecosystems," Dr Madin said.

"The work I will be doing with UTS for the next few years will build on what we have learned to date from studying coral reefs. I am particularly interested in understanding why we can see strong cascading effects from predator loss in some ecosystem types, but less so in others.

Acanthurus_nigricans

Acanthurus nigricans

"A better understanding of how fishing impacts a diversity of marine ecosystems is vital for fisheries around the world to sustainably manage dwindling fish stocks, as well as to understand how we can best protect and conserve marine environments - for example, through marine reserves. This is particularly true for Australia, where our marine ecosystems and associated fisheries span the full range of tropical to temperate."

UTS Professor of Marine Ecology David Booth said Dr Madin's work would be an important addition to the wide range of research UTS is conducting to understand human impact on marine ecology.

"Liz's research effort will help provide the science behind future policy on how best to adapt our sustainable use of the marine environment in the face of climate change and the loss of key species," Professor Booth said.

Dr Madin's co-authors of the papers published in the US include Professor Robert Warner, Professor Steven Gaines, Dean of the Bren School of Environmental Science & Management and Macquarie University's Dr Joshua Madin.

Further Information: Robert Button, UTS Media Office, +61 2 9514 1734

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