SEA 



SCIENCE 



TOP: Students from the UNC Institute 

 of Marine Sciences had buckets of shells 

 ready for the reef restoration project. 



BOTTOM: Oyster reefs provide a grand 

 underwater Imbitatfor a variety of 

 marine species, including juvenile fish. 



FAR RIGHT: Oyster shells create a 

 craggy shoreline. 



The state 

 invests around 

 $700,000 each 

 year restoring 

 ever-diminishing 

 oyster reefs. But 

 the total annual 

 oyster harvest is 

 not much more 

 than that — about 

 $800,000 to 

 $900,000 — and 

 most does not 

 come from 

 restored reefs, 

 according to Mike Marshall, fisheries biologist 

 for the N.C. Division of Marine Fisheries 

 (DMF). The math can make oyster reef 

 restoration appear less than profitable. 



But Grabowski had a hunch that 

 investments in oyster reef restoration pay back 

 more than is readily apparent on a balance 

 sheet. With funding from the N.C. Fishery 

 Resource Grant Program (FRG), he got a 

 chance to test his oyster market theory. 



It starts with the common American or 

 eastern oyster — Crassostrea virginica to 

 scientists. A study in craggy gray asymmetry, 

 it's not what could be called pretty. It's not 

 picky, either. Oysters stick to almost any solid 

 surface in the estuary — along shorelines, 

 clinging to pilings or glued to almost any 

 accumulated detritus. Throw in a concrete 

 block; grow a small oyster garden. 



Oysters can withstand days of inhospi- 

 table conditions just by clamming up. They 

 tolerate a wide range of temperatures, salinity 

 and oxygen levels. En masse, they form 

 fortresses of razor edges standing at attention. 



Yet, despite its resilience and penchant for 

 proliferation, the oyster is in trouble. The nearly 

 2 million bushel harvest in North Carolina at 

 the turn of the 20th century had dropped to 

 about 300,000 bushels by the 1920s and 1930s. 



And the state's oyster harvests continue to 

 decrease each year — from 95,000 pounds in 

 1997 to 54,000 in 1998 and 39,000 in 1999. 



"It is reported that (oyster reefs) were so 

 extensive they were obstacles to navigation" in 

 the Neuse River, Grabowski adds. Today, 



oyster rocks are hardly grand enough to be 

 thought of as reefs. 



Reefs are formed when millions of tiny 

 oyster larvae are released from parent oysters 

 and drift to suitable solid surfaces where they 

 attach and grow. They have a particular 

 affinity for the shells of other oysters. Under 

 the right circumstances, the result is genera- 

 tion upon generation forming huge aggrega- 

 tions that, like the more photogenic coral 

 reefs, can support a busy array of other life 

 forms. 



It may not be our appetite for oysters so 

 much as our means for appeasing it that began 

 the downfall of the grand oyster reefs. The use 

 of mechanical dredges for harvesting oysters 

 around the turn of the century probably 

 caused the earliest and most profound losses, 

 Grabowski says. Dredges "hammered oyster 

 reefs," he says, "and removed the foundation 

 upon which oysters had setded previously." 



Paradoxically, one reason for the 

 continuing decline, is water quality deteriora- 

 tion — a problem oyster reefs could 

 potentially help to alleviate. 



Most scientists believe bivalves such as 

 oysters contribute to good water quality 

 because of their filtering ability, Marshall 

 says. There are no quantitative data on the 

 benefit to the estuary, he adds. But if oysters 

 help purify water, then the larger the reef, the 

 more significant the benefit is likely to be. 



In addition to effects on water quality, 

 oyster reefs help stabilize salt marshes, 

 "providing refuge, food and nursery grounds 

 to a diverse assemblage of animals," 

 Grabowski reports. 



But restoring oyster reefs is a little like 

 replanting a rain forest. It's difficult to rebuild 

 an ecosystem, especially if the conditions 

 under which the original system developed 

 have changed or no longer exist. 



"It can be difficult for extremely 

 impaired systems to recover on their own — 

 restoration may be the only viable option for 

 returning the integrity of these impaired 

 systems," Grabowski says. 



"Often ecologists talk about 'stable 

 states' in the applied sciences," Grabowski 

 says. It's difficult to shift the system back 



24 SPRING 2001 



