If you’ve ever been in the coastal South, you may understand the importance of oysters, but have you ever really listened to them?

The bivalves are not only a favorite food served at almost every restaurant lining the Atlantic for the salty satisfaction of tourists and locals alike, but they are also important to the sound’s natural filtration system — a single oyster can filter up to 50 gallons of water every day. Oysters are also used in living shorelines as a barrier that diffuses wave energy and protects shorelines from erosion. And scientists listening to underwater recordings are discovering that oysters that colonize cultch reefs may also do a lot more.

In a study summarized in a recent post at North Carolina Sea Grant’s Hook, Line & Science blog, researchers from North Carolina State University explored how fish use cultch reefs, or reefs created by depositing shell and other material in shellfish waters, as habitat. Over a span of two years following restoration, they used underwater sound recordings and traditional methods of netting and trapping fish to measure the diversity and frequency of life in the oyster reef. Their findings showed many diverse species of fish and other aquatic wildlife use oyster reefs as habitat and that underwater recordings are useful in determining which species are present.

It’s not necessarily a groundbreaking concept that fish are hanging out around oyster reefs, but the kind of acoustic recording the researchers used helped them refine previous estimates of fish populations around cultch reefs, because trap-and-net techniques only provided a narrow glimpse of the species living around them.

Other researchers have listened to oyster reefs, before. In a 2013 survey, then-doctoral candidate Ashlee Lillis of N.C. State worked with adviser David Eggleston to discover that free-floating larval oysters relied on sounds emanating from oyster reefs to determine where to land. These baby bivalves prefer to attach to other oysters or similar hard substrate, and the sounds that oyster reefs produce act as a beacon of safe harbor.

“…an ocean reef has very loud, distinct sounds associated with it,” Lillis said in an article published in 2013 on N.C. State’s news site. “Even though oysters don’t have ears and hear like we do, they might be able to sense the vibration from the sounds of the reef.”

An oyster reef’s soundscape is often dominated by fish such as red drum, croaker and perch. The study showed that not only are there more fish than previously estimated, there’s more biodiversity as well, including high numbers of native species. That’s a potential economic boost for the fishing industry.

Seth Theuerkauf, aquaculture scientist at The Nature Conservancy, said there’s an important balance when it comes to reef fishing.

“Recreational fishing generally does not negatively impact oyster reefs, as it is non-destructive and typically does not impact oysters or the reef structure/habitat,” Theuerkauf said in an email response. “The benefits of enhanced activity draw attention to those reefs and increase their importance to the public.

“… it’s far easier to have support for conservation of existing reefs and restoration of new ones if the general public is able to benefit from their presence in a no- or low-impact way.”

Joel Fodrie, assistant professor at the University of North Carolina Institute of Marine Sciences in Morehead City, said the way fish are always on the move makes it hard to pin down whether reefs produce more fish or simply attract them.

“An individual fish may only use a habitat once in its life, and it might have been very valuable for it, but then it’ll move on,” Fodrie said. “Maybe it’ll come back, and maybe not. We still don’t quite know the answer.”

Matt Kenworthy, a recently graduated doctoral student who worked with Fodrie on a study of fish and cultch reef interactions in the New River estuary, agreed. “These constructed cultch reefs that were designated for oyster enhancement are not necessarily more attractive to the transient species,” he said.

Kenworthy noted that even if reefs just attract, or aggregate, fish, they also provide a permanent home for smaller organisms, too.

“Data might say the more structure you have, you do get more bivalves, you get more worms, you get more crabs and shrimp,” he said. “The things that are more tightly associated with fish structure, you do see more of. Critters seem to be attracted to structure.”

But while oyster restoration sites are being developed, natural oyster reefs are declining. Fodrie said North Carolina had lost 90 to 95% of its oyster reefs, but the number of natural sites still existing far outweigh the number of planted sites.

“What does that mean for fish?” Fodrie asked. “If we’re in a world where we only have 10% of those reefs, do we only have 10% of those species?”

Answering that question may not get any easier, especially with ongoing damage to oyster reefs from certain commercial harvesting practices and the ever-constant movement of fish.

“Oyster harvesting can certainly impact the reef structure, which can have negative impacts on the ability of that area or reef to provide habitat,” Theuerkauf said. “During harvest, if there is not adjacent reef habitat that is not harvested, then yes, there are likely to be substantial negative habitat impacts to fish and invertebrate species.”

Kenworthy said it’s possible to avoid long-term damage to the reef, but it depends on how much reef structure is degraded through the harvesting process. “In the short term there’s going to be a negative effect. The question is: Can that habitat regenerate, or have we removed enough of that hard substrate that new baby oysters cannot then go settle on?”

But providing a structure for fish to shelter in, even if only for an hour before moving on to their next underwater oasis, is a step in the right direction for increased biodiversity — and increased oyster production.

“You have a top-down influence of fish reducing the number of oyster predators or causing oyster predators to not be as active,” Fodrie said.

But the symbiotic relationship isn’t universal.

“Some of the fish, like black drum, like to eat oysters, so they’re eating the things that eat oysters and they’re eating oysters too,” Fodrie added.

Learn More

• Division of Marine Fisheries cultch planting sites

NAGS HEAD – The staff at Jockey’s Ridge State Park has a vision.

The taxidermy pelican will be standing tall on a lofty perch, overlooking the scene beneath as visitors old and new crowd the park’s visitor center. They will be welcomed to the updated center with plenty of natural light, seating and a welcome desk perfectly placed to receive guests without being obtrusive. The open floor plan will allow for different sections of the center to flow together, so the lobby, exhibit hall and auditorium feel less discrete and more integrated with each other.

Alongside these architectural changes, the exhibit hall will be completely gutted, and new exhibits with a focus on the different ecosystems found in the state park will be installed, allowing visitors to “walk through” the park and its environmental factors before ever setting foot in the dune’s sand.

As Superintendent Joy Greenwood recently explained the changes and the future appearance, sharing blueprints and leading an exhibit hall tour to point out where and how things will change, her vision of an improved visitor experience became clearer.

The planned updates stem from the Connect NC bond referendum, which was approved by state taxpayers in 2016 and grants $75 million to improvement projects on 45 state parks. The referendum distributed the money based on need, and Jockey’s Ridge came away with $751,000 to bring new life to the visitor’s center, which hasn’t seen a substantial update since 2001.

Jockey’s Ridge brought in EVOKE Studio Architecture of Durham and Design Dimensions Inc. of Raleigh for the design process. A construction firm has yet to be selected.

The exhibit updates will mainly focus on educating visitors about the different ecosystems found within the park. The design encourages visitors to flow from dune exhibits to the maritime forest display and then on to the estuarine exhibit. The smoother transition between displays, where previously there were about 11 different exhibits with choppy information about the different aspects of the park’s historical and natural roots, will remain true to the same general concepts, said interpretive designer Tim Rayworth.

Rayworth is heading the project from his home base in Raleigh.

“The new exhibits present a completely different way of looking at Jockey’s Ridge: zooming out to view it as part of the long spit of sand which makes up the Outer Banks, and then zooming in to the level of individual creatures making homes in this ever-changing landscape,” Rayworth said via email. “In some ways the exhibits will be more comprehensive, and in others they will be more focused.”

The center’s nocturnal exhibit and taxidermy will stay because those current elements are among the biggest draws. Greenwood said she wants visitors of all ages, backgrounds and learning levels to be able to understand the ecosystems at work within the park.

“We try to write (the exhibits) on an eighth-grade level,” she said.

Rayworth also stressed the importance of reaching a wide audience. “Most of the million-plus people that come to Jockey’s Ridge spend a week on the Outer Banks and then return to their homes, usually hundreds of miles away,” he said. “I think the exhibits will give them a way to better understand what this place is all about. For local people, we are creating spaces that celebrate their familiar surroundings and heritage.”

Architecturally speaking, the mission is to create a welcoming, open space.

“Typically, museums feel this need to have a dark ceiling and closed-off rooms,” Greenwood said. She admitted that Jockey’s Ridge falls into this category, with a confusing layout and a distinct separation between the lobby, the auditorium and the exhibit hall.

The visitor center updates include installing large windows and glass doors, as well as a wide bench for patrons. Natural light and colors are to feature prominently in the modern design, and the lobby, exhibit hall and auditorium will blend together to improve flow.

“We’re going to take down a wall,” Greenwood said. “It will feel less like a dark hole. We’re really going to open it up.”

Not only will the visitors’ section of the center be revamped, but park staff will also get extra room to breathe. A 22-foot extension of the building will create a room for staff meetings and allow each employee their own space, instead of sharing cubicles as they do now.

Excitement over the updates, however, has been dampened by a possible delay.

Current flood maps show the building’s in an area at risk for flooding, and the entire structure would need to be raised about 6 to 8 inches, which would suck most of the funding dry. But not so with new, pending flood maps.

The issue is the new maps’ release was postponed to February, meaning the project would be on hold until then, unless the park can get county approval to proceed. The delay would make it likely that the visitor center would be closed for much of next summer.

Rayworth, however, remained optimistic.

“Opportunities and inconveniences for visitors and staff come up unexpectedly but regularly,” Rayworth said. “Making the most of them is the trick.”

All of this comes during a hectic time for the staff. Work was recently finished a restoration project in which sand was removed from the southeast section to the northwest part of the park to offset the dunes’ migration driven by prevailing northerly winds. The sand was used to renourish the soundside beach. No sand was removed from the park and no sand was brought in.

Also, Jason Brown, lead interpretation and education ranger at the park, recently accepted a position with the North Carolina Coastal Reserve and National Estuarine Research Reserve. Brown’s departure stretches the staff thinner in their daily duties, while they’re still brainstorming, writing and designing new exhibits. Despite any setbacks, the staff remains hopeful and excited for the changes to come.

“We’re excited for the face-lift,” Greenwood said. “It’s a long time overdue.”

Learn More

• Jockey’s Ridge State Park