A unique group studies drainage impacts on estuaries 



Estuaries: They are the nursery 

 grounds and habitats of many valuable 

 fish. They are the coastal mixing bowls 

 of fresh and salt water. Wrong 

 amounts of fresh water from upstream, 

 and the balance is upset. And that may 

 be the biggest problem facing the es- 

 tuaries today. According to Connell 

 Purvis, director of the state's Division 

 of Marine Fisheries, a balanced 

 salinity is especially critical in the 

 primary nursery areas. "Add too much 

 fresh water too often," he says, "and 

 fish are either killed off or driven 

 away. There is a direct relationship be- 

 tween salinity changes and the produc- 

 tion of commercially important 

 species." 



Maintaining a stable rate of salinity, 

 however, is not an easy task, For 

 openers, there is very little research 

 which quantifies salinity changes and 

 the damaging effects that occur from 

 accelerated freshwater runoff. There 

 are data which indicate that the fre- 

 quency and quantity of fresh water are 

 important factors, and that the 



Photo by Ralph Mills 



greatest salinity changes occur in the 

 upper reaches of the estuaries, the 

 shallow creeks and bays. It is also 

 known that organisms are not as abun- 

 dant in areas receiving direct drainage. 

 They are either killed during a peak 

 runoff period, after a rainstorm, or 

 they move to other, often less produc- 

 tive sites. 



Agricultural and industrial develop- 

 ments on the Coastal Plains use 

 ditches and canals to drain land, often 

 directly into the estuaries. While this 

 isn't the only method of drainage, it 

 has been effective and cost-efficient in 

 the past. After a rain, the suddenly in- 

 creased flow of water from such 

 drainage systems can damage es- 

 tuarine life. 



There may be alternative methods 

 for drainage. If so, then we need to 

 determine their effects on salinity and 

 estuarine production, and devise ways 

 for land users to work in harmony with 

 the estuaries. This year, Sea Grant is 

 funding a project that will study these 

 ways and seek the best solution for the 



salinity problem. B. J. Copeland, 

 director of Sea Grant, says, "If we are 

 going to solve this drainage problem as 

 it relates to estuarine productivity, we 

 are going to have to develop in- 

 novative ways to deal with drainage. 

 There needs to be a balance of fresh 

 and salt water to maintain the produc- 

 tivity of those animals we are in- 

 terested in eating. The quality of the 

 product is definitely related to the 

 stability of the estuarine system." 



To cover the broad spectrum of the 

 issue, a team of researchers represent- 

 ing several disciplines is involved. 

 Each researcher will focus his work on 

 Rose Bay, which is considered one of 

 the most productive areas for fishery 

 products in the Pamlico Sound system. 

 In addition, there are already baseline 

 data available on Rose Bay, and this 

 area is also being affected by existing 

 drainage canals. The following re- 

 searchers are on this project: 

 — Providing information on current 

 agricultural practices are two North 

 Carolina State University (NCSU) re- 

 searchers: Wayne Skaggs from the 

 Department of Biological and Agri- 

 cultural Engineering and Wendell 

 Gilliam from Soil Science. Jimmy 

 Gregory of NCSU's Department of 

 Forestry will be adding data on 

 forestry practices. In previous work on 

 the Coastal Plains, Skaggs developed a 

 numerical model which simulates cer- 

 tain drainage methods combined with 

 long-term weather data. This model 

 will be tailored to the Rose Bay area to 

 determine what effect drainage alter- 

 natives have upon fluctuations of 

 freshwater runoff. 



— Len Pietrafesa of NCSU's Marine, 

 Earth and Atmospheric Sciences 

 Department is developing a physical 

 model of Rose Bay. By monitoring the 

 area before, during and after storms, 

 he is going to define the physical func- 

 tions which determine salinity changes 

 during runoff and create his model 

 with this data. 



— A biological model of the area is be- 

 ing developed by John Miller and Jim 

 Reed of the Zoology Department of 

 NCSU. Miller and Reed are studying 

 the effects of salinity changes on the 

 production of juvenile shrimp, spot 

 and croaker. Rose Bay provides the 

 nursery grounds for these commer- 

 cially important species. Field experi- 



Wayne Skaggs checks equipment which records water table fluctuations 



