TOP: Posey places a cage on the 

 muddy sand flat. 



BOTTOM: A research team member 

 records data. 



alongside veteran fisher Henry Daniels. 



In recent years, there has been no 

 shortage of opinions about the environmen- 

 tal impacts of inshore trawling. 



Some say trawling is good for 

 productivity of inshore waters, "cultivating' 

 the bottom sediments and stimulating 



growth of the tiny 

 creatures that live there. 

 Others say trawling is bad 

 for these waters, unsettling 

 the communities and 

 disrupting their biomass or 

 weight and volume and 

 ability to reproduce. 



The study is impor- 

 tant because the bottom 

 areas affected by trawling 

 are a prime habitat for soft- 

 bottom organisms that are 

 important food for larger 

 fish, shrimp and crabs. 



The research targeted three types of 

 organisms. Benthic microalage are 

 important plant producers, especially for 

 small bottom-dwelling animals. Meiofauna 

 live in-between sand grains and are small 

 enough to be prey for shrimp and small 

 bottom-feeding fishes. Macrobenthos include 

 worms, amphipods and clams and are a food 

 source for larger fishes, shrimp and crabs. 



"We found no significant effects of 

 experimental trawling on soft bottom 

 organisms," says Posey. "However, there 

 were some differences between trawled and 

 untrawled areas. The differences vary 

 between areas, between years, and among 

 different types of organisms. More work is 

 needed to determine which, if any, of these 

 differences are actually due to the chronic 

 effects of trawling." 



Oyster Filters 



Through Sea Grant support, Posey and 

 Alphin also are studying how the genetic 

 selection of the American oyster or 

 Crassostrea virginica may influence water 

 quality. 



Healthy oysters serve as a natural 

 water-filtration system by cleansing 

 estuaries of suspended material, consuming 

 excess algae and promoting growth of 

 vegetation. 



As more people move to coastal areas, 

 water-quality problems are expected to 

 increase. 



"The development of oyster popula- 

 tions that are tolerant to low water-quality 

 parameters, especially turbidity and 



increased nutrients, is important," says 

 Posey. "The establishment of populations of 

 tolerant oysters would help to create a 

 source of larvae to replenish dwindling 

 stocks, enhancing fishery habitats and 

 possibly affecting the water quality through 

 filtering." 



To develop a tolerant strain of native 

 oysters, Alphin, Posey, and Sea Grant 

 researcher Ami Wilbur are examining 

 natural adult populations in two different 

 water-quality environments. 



"Results obtained will be a first step in 

 determining possible selection among oyster 

 populations," he says. 



Posey also is investigating the value of 

 oyster reefs as a fishery habitat. 



"Because currently employed harvest- 

 ing practices for oysters are destructive to 

 the entire reef, evaluating the use of reefs is 

 important for properly managing, protecting 

 and restoring these habitats and associated 

 fisheries," he says 



It has been well documented that reefs 

 are critical habitats for oysters, Posey says. 

 "However, we have not determined if oyster 

 reefs qualify as essential fish habitat for 

 other important species," he adds. "We 

 currently are looking at how reefs are used 

 by fish, crabs and shrimp under a variety of 

 conditions." 



Both North Carolina and Virginia have 

 efforts underway to restore oyster reefs for 

 their habitat value. However, these restora- 

 tion efforts require a firm understanding of 

 factors that influence the quality of oyster 

 reefs as habitat, such as the vertical relief of 

 a reef, the size of oysters, or closeness to 

 other habitat types, says Posey. 



As Posey looks into the Cape Fear 

 River, he says that all his projects are 

 interrelated. 



"All our projects are centered on the 

 food web," he says. "We need to develop a 

 better understanding of food- web dynamics 

 in estuarine systems. Many nearshore 

 estuaries are important habitats for shrimp, 

 blue crabs and oysters." El 



To find out more about Posey's 

 research, log onto: www.uncwil.edu/cmsr/ 

 benthic. 



COASTWATCH 45 



