How freshwater in big doses threatens fisheries 



The problem: freshwater drainage into saline 

 estuaries 



Coastal lowlands, once thought to be wastelands of 

 soggy mire, are being cleared and drained at an increas- 

 ing rate. Farmers have learned that drained wetlands can 

 be among North Carolina's most productive agricultural 

 acreage. 



The water drained from these wetlands usually ends 

 up in the estuaries, and can affect nursery areas for most 

 of the state's commercial and recreational fishes. 



Scientists, resource managers, fishermen and others 

 are worried the freshwater influx is affecting the makeup 

 of the estuaries (salinity levels, turbidity and nutrient 

 levels) and in turn affecting fisheries production. 



The research: studies to measure the volume of 

 freshwater influx, changes in salinity and the ef- 

 fects on fishes 



Three new UNC Sea Grant projects will study land 

 drainage, focusing the efforts of scientists from different 

 fields to provide the missing links in the land drainage- 

 estuarine knowledge available. 



Wendell Gilliam and Wayne Skaggs will be examining 

 the rate of freshwater influx into the estuaries. They will 

 measure the rate and volume of freshwater flow from 

 drainage ditches into the estuaries over a variety of 

 conditions — soil type, rainfall, canal construction. The 

 team will also be looking at different ways for farmers to 

 drain land while minimizing the effects of drainage on the 

 estuaries. 



Len Pietrafesa will be using Gilliam and Skaggs' 

 findings to study the effects of drainage on salinity pat- 

 terns in the estuary. In turn, John Miller and Jim Reed 

 will be examining the effects of salinity changes on the 

 production of juvenile fishes and shrimp in the estuary. 



(Watch for more on the land-drainage problem in 

 future issues of Coastwatch) 



Drainage canal under construction 



The researchers: 



J. Wendell Gilliam, Department of Soil Science, North 

 Carolina State University 



R. Wayne Skaggs, Department of Agricultural Engineer- 

 ing, North Carolina State University 



Len Pietrafesa, Department of Marine, Earth and At- 

 mospheric Sciences, North Carolina State University 



John Miller, Department of Zoology, North Carolina 

 State University 



Jim Reed, Department of Zoology, North Carolina State 

 University 



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