Fear of sharks helps preserve balance in the world's oceans

Jun 04, 2013 by Lilyvania Mikulski

(Phys.org) —A prey's fear of a shark is critical to protecting ocean biodiversity, according to researchers at Florida International University. Without this fear, a cascading effect within the ecosystem could destabilize the world's oceans.

provide habitats for other fish and marine life—many of which people rely on. When predators, such as , rove in areas near seagrasses, including turtles and often navigate away from these areas. This prevents the seagrasses from being devoured to the point of elimination.

"Predators can have major impacts without having to eat anything, because animals will change their behavior to avoid becoming a meal," said Mike Heithaus, researcher and executive director of the School of Environment, Arts and Society at FIU. "If there are no predators to fear, these grazers will take advantage."

The findings were published today in the Journal of Animal Ecology.

Heithaus, Derek Burkholder and James Fourqurean all of FIU, along with researchers from the University of Washington in Seattle and Simon Fraser University in Canada, amassed more than 15 years of studies of predators and prey combined with experimental work within the seagrass beds of Shark Bay, Australia. This is the first study to examine the viability of seagrasses where herbivore, shark and seagrass populations are intact. Heithaus recently co-authored another study that suggests as many as 100 million sharks are caught every year, far exceeding their reproductive rate.

"There just aren't many places where sharks are still around in big numbers," Heithaus said. "The most important thing to take away is that large sharks are critical for the health of ecosystems. If we lose the sharks, we could lose seagrasses that are habitats for fish that fishermen want to catch. It's a cascading effect that has far-reaching implications."

The researchers insist that protecting these top predator populations must be a priority.

"We really need to start looking beyond just protecting what's left," Heithaus said. "We need to start talking about rebuilding these populations."

Explore further: Stanford researchers rethink 'natural' habitat for wildlife

More information: onlinelibrary.wiley.com/doi/10.1111/1365-2656.12097/abstract

add to favorites email to friend print save as pdf

Related Stories

Tiny grazers play key role in marine ecosystem health

Apr 02, 2013

Tiny sea creatures no bigger than a thumbtack are being credited for playing a key role in helping provide healthy habitats for many kinds of seafood, according to a new study by the Virginia Institute of ...

White shark diets vary with age and among individuals

Sep 28, 2012

White sharks, the largest predatory sharks in the ocean, are thought of as apex predators that feed primarily on seals and sea lions. But a new study by researchers at the University of California, Santa ...

Recommended for you

Plants with dormant seeds give rise to more species

Apr 18, 2014

Seeds that sprout as soon as they're planted may be good news for a garden. But wild plants need to be more careful. In the wild, a plant whose seeds sprouted at the first warm spell or rainy day would risk disaster. More ...

Scientists tether lionfish to Cayman reefs

Apr 18, 2014

Research done by U.S. scientists in the Cayman Islands suggests that native predators can be trained to gobble up invasive lionfish that colonize regional reefs and voraciously prey on juvenile marine creatures.

User comments : 0

More news stories

Researchers successfully clone adult human stem cells

(Phys.org) —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...

Airbnb rental site raises $450 mn

Online lodging listings website Airbnb inked a $450 million funding deal with investors led by TPG, a source close to the matter said Friday.

Health care site flagged in Heartbleed review

People with accounts on the enrollment website for President Barack Obama's signature health care law are being told to change their passwords following an administration-wide review of the government's vulnerability to the ...