SEA 



SCIENCE 



Floyd Follow-up 



The Lingering Effects 



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, spring turns into summer, 

 North Carolina Sea Grant researchers have a 

 watchful eye on coastal waters — and they 

 will have some high-tech eyes as well. 



Efforts to determine lingering effects of 

 unprecedented flooding last fall will be 

 bolstered by monitors on state ferries, 

 remote imagery from the SeaWifs satellite 

 of the National Oceanic and Atmospheric 

 Administration (NOAA), and permanent 

 monitoring stations along the Neuse River 

 and estuary. 



And there may be one silver lining in 

 2000 to the devastating hurricane season of 

 1999: Outbreaks of toxic Pfiesteria are 

 usually low after major storms. 



'1 am hoping we will have a quiet 

 year," says Jo Ann Burkholder, an aquatic 

 botanist at North Carolina State University 

 and expert on Pfiesteria. 



The flooding that accompanied 

 Hurricane Floyd had identifiable short-term 

 effects on coastal waters: an increased load 

 of nutrients and decreased levels of oxygen 

 and salt in estuaries. 



While the fast-moving Cape Fear 

 system may have recovered fairly quickly, 

 the turnover is much slower in the Pamlico 

 Sound, a major nursery area that is still 

 showing signs of stress. 



"We are finding much smaller 

 yearlings. Fish that should have been 6- to 8- 

 inches by spring were still only 4-inches 

 long. Clearly, their reduced growth is linked 

 to the stressed environment," Larry 

 Crowder, a marine biologist at the Duke 

 University Marine Lab, says of sampling in 

 the Pamlico. 



Crowder and others will continue to 



By Katie M o s her 



monitor various species as they advance 

 through the life cycle this year. He expects 

 to see other signs of prolonged stress on fish 

 that were trapped in the sound when Hoyd's 

 freshwater plume arrived. 



Such data would support laboratory 

 findings of NC State zoologist James Rice, 

 graduate student Regan McNatt and Edward 

 Noga of the NC State College of Veterinary 

 Medicine. The team studies the impact of 

 low levels of oxygen — known as hypoxia 

 — on the feeding, growth 

 and immunity of juvenile 

 estuarine-dependent fish. 



They found that fish 

 exposed to low-oxygen rates 

 for prolonged periods had 

 reduced growth rates and 

 weakened immune systems. 



"Although it is well- 

 documented that acute 

 hypoxia can lead to fish kills, 

 few studies have measured 

 the direct effects of sublethal 

 hypoxia on fish," says Rice. 



"Increased vulnerability 

 to disease may lead to 

 greater mortality, and 

 decreased growth can also 

 reduce production by fish 

 populations." In particular, the study found 

 that natural antibacterial activity decreases 

 as dissolved oxygen levels decrease. 



SIGNALS AND CYCLES 



Why did some commercial fishers 

 report record landings in the fall, while 

 others qualify for disaster assistance because 

 of limited catches? 



Some researchers and state officials 

 suggest that heavy rains from Hurricane 

 Dennis — which lingered on North 

 Carolina's coast for two weeks — may have 

 dumped enough fresh water into the 

 Pamlico and upper estuaries to signal more 

 mature sea life to leave the sound. Some 

 fishers were well-positioned for the 

 bounteous catch. Changes in traditional 

 fishing grounds could continue. 



Thus researchers also are following the 



fate of the larval fish that are transported 

 from the open sea into the sound's nurseries 

 in March and April. 



Will the low salinity levels hinder the 

 larval fish, including croaker, flounder and 

 pin fish that support North Carolina's 

 lucrative fisheries? 



Or, Crowder asks, "Could larval fish 

 actually benefit from the additional nutrient 



24 EARLY SUMMER 2000 



