Research on the Half Shell

By Jessica Riviere

Oysters, the mighty mollusks that season holiday dressing, draw 30,000 visitors to a fall festival in Brunswick County and flavor coastal life in North Carolina, could use some help these days. Fishing pressure, worsening water quality and disease have reduced oyster populations on the east coast to the lowest levels in 100 years.

NC State researchers and partners will lend a hand with a project to revitalize oyster beds along the Pamlico Sound and create jobs in an industry that has suffered during the recent economic downturn.

“We’re proud to be part of something that can have long-term benefits for both the marine life and those who make a living from it,” says lead investigator Dr. David Eggleston, director of NC State’s Center for Marine Sciences and Technology (CMAST) and professor of marine, earth and atmospheric sciences.

The National Oceanic and Atmospheric Association (NOAA) has given the N.C. Coastal Federation a $5 million stimulus grant to build two large oyster sanctuaries along the Pamlico Sound. The oyster reefs, which will be created with 54,000 tons of stone, will cover over 46 acres.

As designated oyster sanctuaries, the reefs will not be harvested, but they will benefit both commercial and recreational fishermen as nurseries for oysters and valuable fish species. Computer modeling studies have shown that these oyster reefs produce larvae that travel to other parts of Pamlico Sound where they will mature and can eventually be harvested.

About $300,000 will go to NC State, NC Sea Grant and the University of North Carolina at Wilmington for monitoring the project.

Scientists will measure four ecological aspects of  large-scale oyster restoration: density, size and frequency of oysters in existing and newly created habitat; settlement of oyster larvae on oyster shells over time to indicate whether populations are increasing, abundance, size and diversity of other species that use oyster reefs as habitat, such as fish and crabs; and any positive changes to recreational fishing opportunities and catch-per-unit effort.

Using a variety of gear and personnel, from professional scuba divers to high school volunteers, Eggleston and his team will measure the project’s impact. The scuba divers will retrieve clumps of oysters from the seafloor for counting and measuring, then the divers will replace the clumps.

Students located throughout the Pamlico Sound region will retrieve “shell-strings” hanging from docks and take water quality measurements. Each of three shell-strings will be replaced weekly with a fresh set, and those that have been sampling the water will be examined in the laboratory at NC State, enabling the team to identify and count newly settled oysters.

“This gives us a relative measure of oyster settlement in space and time, and we can examine annual settlement as a function of the amount of oyster reef restoration to see if there is a relationship,” Eggleston says.

Gill nets, fish traps, minnow traps and crab traps will be used to assess other species that may inhabit oyster reefs and that will likely respond positively to this habitat restoration effort. Changes in recreational fishing opportunities and catch-per-unit-effort will be assessed using a combination of creel surveys of fishermen at boat ramps, aerial surveys of the number of boats and anglers at oyster restoration sites, and follow-up phone interviews with recreational anglers.

Computer models will simulate currents and oyster larval dispersal in Pamlico Sound to estimate the larval connectivity of the different sanctuaries, and mathematical population models will tie together all the data from modeling, the field and the laboratory, to estimate the  impact of this large-scale restoration effort on the overall oyster population in Pamlico Sound.

The science team will consist of about eight people and create 140 jobs over an 18-month period, many of them in industries hard-hit by the economic downturn. Commercial fishermen, quarry workers, tug boat and barge operators, and fisheries technicians are among those who will be employed during the project.