SEA 



SCIENCE 



once it's been damaged, he explains. In the 

 case of oyster reef restoration, his FRG-funded 

 study shows it's worth the effort. 



• OYSTER REEF RESTORATION 



The preferred substrate for reef restoration 

 is oyster shell, most of which comes from the 

 shucking industry, Marshall says. Shells from 

 other bivalve mollusks, like clams or scallops, 

 also can be used. Another alternative is marl — 

 fossilized sedimentary rock that contains a 

 substantial amount of calcium carbonate, a 

 main ingredient in oyster shells. 



Marshall describes two methods used to 

 rebuild oyster reefs. In shallow, tidal estuaries 

 in the southern coastal region where the moon 

 affects tides, reef material is sprayed off the 

 decks of boats into areas marked off with 

 pilings. 



In deeper, subtidal estuaries of the 

 northern areas where tides are wind-driven, the 

 material is dumped into piles with a front-end 

 loader into areas marked off by buoys. Since 

 the water is deeper, the reef materials can be 

 mounded to taller elevations providing a 

 habitat above areas that suffer from low 

 dissolved-oxygen levels. 



Grabowski's study — along with those of 

 Charles "Pete" Peterson and Hunter Lenihan of 

 UNC-CH — is providing important data, 

 according to Marshall, and can help determine 

 the best sites for restoring reefs. 



• BUILDING REEFS 



Grabowski restored reefs in Middle 

 Marsh, Carteret County, in three types of areas 

 where oyster reefs tend to form naturally. 

 These areas, or landscapes, are edges of salt 

 marshes isolated from sea grass habitat, areas 

 between salt marshes and sea grass beds, and 

 mudflats away from vegetation. 



Shells and the use of shallow-draft barges 

 for Grabowski's study were provided by DMF, 

 with Marshall and Jeff French, also of the 

 division, collaborating. "Though oyster reefs 

 have only recently received recognition as a 

 habitat to protect rather than a single-species 

 resource to exploit, DMF has remained 

 committed to assisting reef research and has 

 been instrumental to the successful design and 



completion of several 

 important restoration 

 projects over the last 1 5 

 years," Grabowski points 

 out. 



Also essential to the 

 study was the fishing 

 expertise of several 

 members of the 

 Saltwater Light Tackle 

 Fishing Club. Grabowski 

 notes that the club "has a 

 real commitment to 

 seeing habitat restored in 

 order to enhance 

 fisheries." 



Shortly after constructing the reefs in 

 1997, sampling began with fish traps, minnow 

 pots, crab pots, gill nets and hook-and-line. 

 Reefs and control areas — similar landscapes 

 without reefs — were sampled to determine the 

 benefits of restored reefs. 



Grabowski's study shows that the oyster 

 is hardly "secret, self-contained and solitary," 

 as Charles Dickens described it. 



Grabowski puts it scientifically. "A wide 

 diversity of mobile animals utilized restored 

 oyster reefs as juveniles or adults during the 

 day and night throughout the year." It could be 

 said that, for many aquatic animals, their world 

 is an oyster reef. Or, perhaps, build it, and they 

 will come. 



• THE BIO-DIVIDENDS 



What makes an oyster reef a hub of 

 aquatic life is partly protection, but, just as 

 likely, the oyster's place in the food chain. Tiny 

 creatures such as boring sponges and various 

 worms feed on oysters. And where small 

 animals gather, larger ones will come. 



The study found white urchins, sea stars, 

 right and lightening whelks, banded tulips, 

 moon snails, grass shrimp, mud crabs and 

 spider crabs in higher abundances on reefs than 

 in controls. 



Fish found to frequent the reefs include 

 our state saltwater fish, the red drum, along 

 with flounder, speckled trout, gag grouper, 

 snapper, blue fish, spottail pinfish, pigfish, 

 toadfish and sheepshead. 



•W% ... 



Juvenile fish were found around all the 

 oyster reefs, Grabowski says, "whether in 

 between sea grass and salt marshes, on the 

 fringes of salt marshes away from sea grass 

 habitat, or on mud flats isolated from 

 vegetation." 



In control areas without reefs, only in 

 sea grass landscapes — areas with aquatic 

 vegetation that is submerged even at low tide 

 — were juveniles found in significant 

 numbers. It seems that reefs function similarly 

 to sea grass beds, Grabowski says, but "since 

 oyster reefs are the only hard substrate in a 

 predominantly soft-sediment environment 

 they provide more stable habitats for juvenile 

 fish and enhance fish production within the 

 estuary." 



For a state investing in oyster reef 

 restoration, biology merges with economics. 

 Studies of stomach contents of fish suggest 

 "that oyster reefs are important foraging 

 grounds for many economically valuable 

 fish," Grabowski concludes. 



But the positive influences on the 

 estuarine environment may be incalculable 

 because so many factors go into the oyster reef 

 equation. "The ecosystem services provided 

 by mud reefs as habitat for juvenile fish, as 

 water purifiers and as habitat stabilizers are not 

 reflected in the economic analysis," 

 Grabowski adds. 



If it's not rocket science, it's not 

 Accounting 101, either. Ultimately, 

 Grabowski asks, "How do you put a price tag 

 on biodiversity?" □ 



COASTWATCH 25 



