Don Reuter (919) 715-4112
November 16, 1999
Testing Shows Improvement in Pamlico Sound Dissolved Oxygen Levels
RALEIGH - North Carolina scientists have confirmed that oxygen levels in the Pamlico Sound and the Neuse River have rebounded out of stressful conditions resulting from floodwaters associated with Hurricane Floyd.
Floodwaters can contribute to hypoxic (low dissolved oxygen and salt levels) conditions in these areas where fresh, brackish and saltwater meet. Hypoxia can lead to stressful conditions for aquatic species and even kill fish when severe. Reports from Hans Paerl, University of North Carolina-Institute of Marine Science, and Larry Crowder, Duke Marine Laboratory, show that the winds generated by Hurricane Irene apparently maintained a long and hard enough northeaster to remix the low oxygen waters in the sound. Also, water temperatures have dropped since the storms, which is having positive effects on dissolved oxygen levels. Both the Division of Marine Fisheries and the Division of Water Quality (DWQ) have conducted monitoring in the sound and have seen similar improvements. Sampling by the Neuse River Rapid Response Team indicates the same mixing of the Neuse.
Salinity levels still remain depressed in portions of the Pamlico Sound and scientists predict that algae blooms could occur as a result of excessive nutrient loading by Hurricane Floyd if hot, still conditions develop next summer. Larry Ausley, water quality supervisor in DWQ's Environmental Sciences Branch, said the areas may experience similar blooms during the winter.
"We sometimes see winter blooms in the estuaries," Ausley said. 'It wouldn't surprise me if these blooms were more intense this winter because of the additional nutrients in the estuaries."
"The combined effect of nutrient-stimulated algae growth, continued freshwater runoff and increasing temperatures next spring and summer may reintroduce low oxygen conditions to the Sound's bottom waters, underscoring the need for a long-term intensive water quality monitoring and fisheries habitat assessment program for this valuable ecosystem," Paerl said.
DWQ continues to monitor water quality conditions in flood-affected areas, checking for dissolved oxygen levels, salinity and other parameters. The latest data is available on the division's Hurricane Floyd web site at http://esb.ehnr.state.nc.us/Floyd.htm.
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