BOGUE BANKS — Decades of beach nourishment have significantly altered the habitat, numbers and distribution of large and small animals on Bogue Banks, but it’s too soon to determine whether the long-term impacts will be positive, negative or neutral.
That’s the conclusion of a study by scientists from around the region, according to interviews and a paper published by MDPI based on the 2020 study. MDPI, or Multidisciplinary Digital Publishing Institute, is based in Switzerland and describes itself as “a publisher of peer-reviewed, open access journals.”
“There are basically two habitats on the (Bogue Banks) beaches now,” said lead author Dr. Steve Fegley of the University of North Carolina at Chapel Hill Institute of Marine Sciences in Morehead City.
One is the fine “sugary” sand you see on the top of the beach, but there are multiple layers of coarse, less-penetrable shelly “hash” under the surface, the researcher and associate professor added in an interview.
The conclusion of the paper, titled “Nourished, Exposed Beaches Exhibit Altered Sediment Structure and Meiofaunal Communities,” states that, “We do not argue whether changes in meiofaunal assemblages in exposed beaches are good or bad regarding beach ecosystem function.
“However, we do assert, due to a persistent alteration of beach sediment composition, that there is evidence that faunal changes have occurred which could alter beach function.”
The results are based on samples scientists and students collected with shovels and syringes and compared to previous samples reported in other studies, according to the paper.
Meiofauna are tiny benthic invertebrates that live in marine and freshwater environments. Benthic organisms include clams, worms, flatworms, oysters, shrimp-like crustaceans and mussels. Worms are meiofauna, while larger organisms, such as shore birds, fish, coquina clams and ghost crabs, are megafauna and higher up in the food chain.
The other principal investigator in the study, Dr. Julian Smith, a biology professor and researcher at Wofford University in South Carolina, said in an interview he was surprised by the results.
“I went into it thinking we might find the same impact on meiofauna as on megafauna, such as shore birds, fish, ghost crabs and coquina clams,” said Dr. Smith, whose area of expertise is meiofauna, especially worms. “There are places where we don’t find coquina clams and ghost crabs.”
While there were differences in the number and distribution of the worms and other small organisms, there was plenty of diversity and less fluctuation in number and diversity than found in a 2017 study on Bear Island, a barrier island in Hammocks Beach State Park, across Bogue Inlet from Emerald Isle. Bear Island has had only one small-scale nourishment.
“We don’t know what this all means for the food web,” Dr. Smith said, “but it was definitely better than we thought it would be. There appears to be much less damage to meiofauna species than megafauna.”
He said, however, there are questions about the long-term implications of Bogue Banks beach nourishment, which began in earnest in the late 1990s on a small scale and increased in scope to the present. Just in the last year, close to 6 million cubic yards of material dredged from the ocean off Atlantic Beach have been placed on the beaches.
Dr. Fegley said he, too, was surprised by the study results.
“We expected to find something comparable to (the impacts) on surf fish and shore birds,” which he said have declined in number during the nourishment period, according to other studies.
The bottom line is that although the beaches along Bogue Banks are different than they were before large-scale nourishment, “we don’t necessarily know if it’s worse,” he said.
Neither scientist criticized nourishment directly and both said when it comes to economics for the area and its tourism-based economy, there’s really no other choice unless you want to harden the shoreline – which illegal in North Carolina – or let the barrier island slowly disappear, the normal trend as the offshore islands under natural processes.
The researchers also said those in charge of nourishment have in recent years done a much better job finding and depositing beach-quality sand than in the past, lessening the habitat changes on the strand.
Dr. Fegley noted, however, that as time goes on, nourishment is going to get more and more expensive, and like Dr. Smith, he said much is still unknown about long-term impacts on organisms.
“It could be bad, it could be good and it could be neutral,” he said.
The paper puts in this way: “Unfortunately, changes to the physical environment of the beach, arising from anthropogenic activities and responses to shoreline erosion, may be altering beach meiofaunal communities in ways that affect beach processes, before we fully understand those processes.”
Other researchers involved in the study and paper came from Duke University in Durham and Barton College in Wilson.
Contact Brad Rich at 252-864-1532; email email@example.com; or follow on Twitter @brichccnt.