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NC - Artificial Reefs Take on a Towering Presence as Havens for Marine Predators

Acting like high-rise timeshares in the sea, shipwrecks and other artificial reefs can support dense populations of sharks, mackerels, barracudas, jacks and other large migratory marine predators essential to ocean health, according to a new study at 30 sites along the North Carolina coast.

Predator densities were up to five times larger at the 14 artificial reefs surveyed in the study than at the 16 nearby natural reefs that also were surveyed

Shipwrecks, especially those that rose between four and 10 meters up into the water column, were by far the fishes' favorite. At some sites, they supported predator densities up to 11 times larger than natural reefs or low-profile artificial reefs made of concrete.

"These finding tell us two important things. One is that artificial reefs can support large predators, potentially supplementing natural reefs if the design and placement of the artificial reefs are strategic," said Avery Paxton, research associate with the National Oceanic and Atmospheric Administration's National Centers for Coastal Ocean Science (NCCOS) in Beaufort, N.C., who led the study.

"The second thing it tells us is that when it comes to designing artificial reefs, there may be such a thing as a height advantage. We observed more fast-moving predators that live and hunt in the water column at the taller reefs in our study," she said.

Climate change, pollution, development and other stresses have accelerated the decline of natural reef ecosystems across much of the world's oceans in recent years, forcing large predators who formerly fed in the water column around the reefs to venture outside their normal migratory routes and native ranges in search of suitable alternatives.

Because these predators help maintain healthy and sustainable populations of species lower in the food web, providing suitable habitat for them as expediently as possible is critical, said Brian Silliman, Rachel Carson Distinguished Professor of Marine Conservation Biology at Duke University's Nicholas School of the Environment, who collaborated on the study.

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