Fishing for answers 



Where land and sea meet 



In eastern Hyde County, some of 

 the state's most productive land lies 

 adjacent to some of its most produc- 

 tive coastal water. But the distinction 

 between the two is vague; much of the 

 land is barely above sea level. 



Farmers have found that these 

 drained wetlands yield bountiful 

 crops — if they can control the water. 

 Ditches drain the fields, and canals 

 carry the runoff to creeks that empty 

 their waters into Pamlico and 

 Albemarle sounds. 



Experts tell us more than 2 million 

 acres in coastal North Carolina are be- 

 ing drained. And the water from those 

 fields ultimately reaches the estuaries 

 that serve as nursery grounds for over 

 90 percent of the state's commercially 

 important fish and shellfish. 



Scientists, resource managers and 

 fishermen are worried that the 

 freshwater influx may be affecting the 

 makeup of the estuaries and in turn af- 

 fecting fisheries production. 



In 1981, the Governor's Coastal 

 Water Management Task Force was 

 formed to make recommendations for 

 improved water management. Re- 

 cently, the N.C. General Assembly ac- 

 ted on those recommendations, ap- 

 propriating money for a study to 

 measure the impact of land drainage 

 on estuaries. Researchers will use 

 Broad Creek in Hyde County as a 

 demonstration site. 



UNC Sea Grant Director B.J. 

 Copeland, coordinator of the project, 

 says the goal is to demonstrate the 

 relationship between an estuarine nur- 

 sery and water management. 



Sea Grant researchers John Miller, 

 Margery Overton and John Fisher will 

 participate in the project. In an earlier 

 Sea Grant project, Miller studied the 

 effects of salinity changes on juvenile 

 fish and shellfish, using Rose Bay as 

 his laboratory. A heavy rainstorm 

 meant a drop in the bay's salinity. 

 Then, he waited for Mother Nature to 

 perform experiments for him. When 

 she did, he analyzed the effects. 



But Miller says the Broad Creek site 

 offers researchers a chance to do more 



than just study the effects of a heavy 

 rainstorm on estuarine organisms. 

 They'll be able to "create" their own 

 rainstorms. 



The flow of runoff into Broad Creek 

 is controlled by a pumping station on 

 the 5th Avenue Canal. (The canals are 

 so numerous that they've been given 

 the names of avenues and streets.) 

 With the help of landowners, re- 

 searchers will manipulate the amount 

 of water entering the nearby estuary. 

 Scientists will use one branch of the 

 creek as a control while they perform 

 experiments on the other branch. 



"This project presents an oppor- 

 tunity to get answers much more ef- 

 ficiently," says Miller. "We'll be able 

 to discharge significant amounts of 

 fresh water into an estuarine area. And 

 hopefully we'll be able to see the im- 

 pact on the biology of systems and how 

 fast they recover." 



Miller has some theories about what 

 he may find at the Broad Creek site. In 

 his research on Rose Bay, he found 



that up to a certain point, a salinity 

 reduction did not produce much 

 change. But further decreases in the 

 salinity resulted in what Miller refers 

 to as "thresholds." 



At the first threshold, the estuary 

 undergoes a temporary change in the 

 distribution of fish and shellfish. At 

 the second threshold, the change may 

 be great enough to force baby fish into 

 areas of higher salinity where they 

 would be vulnerable to predation. 



At the third threshold, the fish pop- 

 ulation could experience permanent 

 reduction, says Miller. The change in 

 salinity might be great enough to cause 

 the death of the fish's food supply or of 

 the fish themselves. 



Miller will be testing the waters of 

 Broad Creek to find out if his theories 

 hold true. He says his strategy will be 

 to determine what those thresholds 

 are. He may begin by reducing the 

 salinity by 50 percent in one day. Or, 

 perhaps he will reduce the salinity by 

 Continued on next page 



Photo from USDA Agricultural Stabilization and Conservation Service 



Fields, ditches and canals near Broad Creek (see arrow) 



