Tropical and subtropical fish are showing up in greater numbers off the North Carolina coast, thanks in part to the dozens of artificial reefs the state created to lure more scuba divers, Duke University researchers say.
“This pattern may continue or even accelerate in coming years, given predictions of warming oceans under climate change,” concluded the study released May 6 by the Duke University Marine Laboratory and NOAA’s Centers for Coastal Ocean Science.
Avery Paxton, a visiting scholar at the laboratory, says data collected over two years revealed the reef networks have become “underwater corridors the fish use to reach the habitats they need to survive,” according to the university.
Among the tropical species found on the reefs were blue chromis, purple reef fish and bluehead wrasse, officials said.
“The artificial reefs created by these structures may be acting as stepping stones for fish that are moving northward and living at the edge of their geographic range, or beyond it, in search of suitable habitat,” Paxton said in a news release.
“Globally, there is broad evidence that many tropical fish species are shifting their ranges poleward and to deeper waters in response to changing ocean conditions, and what we see on these reefs seems to fit that pattern,” Paxton said.
What surprised the researchers the most is that tropical fish preferred man-made reefs to “natural rocky reefs,” according to a statement from J. Christopher Taylor, co-author of the study and a research ecologist at NOAA’s National Centers for Coastal Ocean Science.
That may have something to do with the artificial reefs providing the fish with “more nooks and crannies where they can evade predators,” Taylor said in a release.
North Carolina’s artificial reef system has become an international destination for divers, according to VisitNC.com. The N.C. Division of Marine Fishers has created nearly 70 of the reefs, using 27 derelict boats, old box cars and environmentally safe construction material. Some of the reefs are as far as 38 miles off shore, the state says.
Jordan Byrum, the state’s artificial reef coordinator, told the Charlotte Observer he was “pleasantly surprised” by Duke’s conclusions.
“We have some documented cases of tropical species on our reefs in the warmer months, but nothing more than some photos and anecdotal observations,” Byrum told the Observer. “North Carolina is rich with opportunities to dive wrecks and observe sharks. ... Publicity about some other interesting species on North Carolina’s reefs may prove to be a new focus for dives.”
Duke University researchers say they collected data on fish species at “30 artificial and natural reefs off the N.C. between 2013 and 2015,” according to a release. The data “confirmed that the number and diversity of tropical and subtropical fish on deep artificial reefs was far greater than on nearby natural reefs,” said the report.
More research is needed to determine why the tropical fish prefer the man-made reefs, the report said.