{"id":6830,"date":"2000-06-01T13:17:00","date_gmt":"2000-06-01T17:17:00","guid":{"rendered":"https:\/\/ncseagrant.ncsu.edu\/coastwatch\/?page_id=6830"},"modified":"2024-06-24T19:14:36","modified_gmt":"2024-06-24T23:14:36","slug":"sea-science-floyd-follow-up-the-lingering-effects","status":"publish","type":"post","link":"https:\/\/ncseagrant.ncsu.edu\/coastwatch\/sea-science-floyd-follow-up-the-lingering-effects\/","title":{"rendered":"SEA SCIENCE: Floyd Follow-up: The Lingering Effects"},"content":{"rendered":"\n\n\n\n\n
As spring turns into summer, North Carolina Sea Grant researchers have a watchful eye on coastal waters \u2014 and they will have some high-tech eyes as well.<\/p>\n\n\n\n
Efforts to determine lingering effects of unprecedented flooding last fall will be bolstered by monitors on state ferries, remote imagery from the Sea Wifs satellite of the National Oceanic and Atmospheric Administration (NOAA), and permanent monitoring stations along the Neuse River and estuary.<\/p>\n\n\n\n
And there may be one silver lining in 2000 to the devastating hurricane season of 1999: Outbreaks of toxic Pfiesteria<\/em> are usually low after major storms.<\/p>\n\n\n\n “I am hoping we will have a quiet year,” says JoAnn Burkholder, an aquatic botanist at North Carolina State University and expert on Pfiesteria<\/em>.<\/p>\n\n\n\n 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.<\/p>\n\n\n\n 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.<\/p>\n\n\n\n “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.<\/p>\n\n\n\n Crowder and others will continue to 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 Floyd’s freshwater plume arrived.<\/p>\n\n\n\n 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 \u2014 known as hypoxia \u2014 on the feeding, growth and immunity of juvenile estuarine-dependent fish.<\/p>\n\n\n\n They found that fish exposed to low-oxygen rates for prolonged periods had reduced growth rates and weakened immune systems.<\/p>\n\n\n\n “Although it is well\u00ad-documented that acute hypoxia can lead to fish kills, few studies have measured the direct effects of sublethal hypoxia on fish,” says Rice.<\/p>\n\n\n\n “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.<\/p>\n\n\n\n Why did some commercial fishers report record landings in the fall, while others qualify for disaster assistance because of limited catches?<\/p>\n\n\n\n Some researchers and state officials suggest that heavy rains from Hurricane Dennis \u2014 which lingered on North Carolina’s coast for two weeks \u2014 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.<\/p>\n\n\n\n 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.<\/p>\n\n\n\n Will the low salinity levels hinder the larval fish, including croaker, flounder and pin fish that support North Carolina’s lucrative fisheries?<\/p>\n\n\n\n Or, Crowder asks, “Could larval fish actually benefit from the additional nutrient levels that remain on the bottom of the sound and estuaries?”<\/p>\n\n\n\n Additionally, upriver habitat is still recovering from the triple dose of storm upheaval. If sea grasses \u2014 habitat for gag grouper \u2014 do not make a comeback, this year’s class of fish could be affected.<\/p>\n\n\n\n The jury still is out on overall effects to North Carolina fisheries, researchers and state officials agree. Mother Nature’s final answer will depend on the prevailing weather in spring and early summer.<\/p>\n\n\n\n Warm sunny days could feed algal blooms with more light. Organic materials and fungi will use oxygen to decompose. A wet, warm spring and summer could add more fresh water and nutrients.<\/p>\n\n\n\n What is the best case scenario? A dry and windy spring could evaporate fresh water trapped in the Pamlico and promote its recovery, Crowder says.<\/p>\n\n\n\n The researchers find themselves in new territory as they evaluate the cumulative effects of Hurricanes Dennis, Floyd and Irene, which hit the North Carolina coast within a four-week span in late summer and early fall. Scientists have limited data from 1954-1955 \u2014 when four hurricanes hit North Carolina in a 12-month period \u2014 to help predict how the fisheries will recover.<\/p>\n\n\n\n “This is an opportunity to do groundbreaking research that will help predict, but more importantly help guide management policies of how to manage our resources at a time of greater levels of disturbance,” Crowder says.<\/p>\n\n\n\n A small armada of scientists will continue studying the hurricane effects up and down the coastline. The interdisciplinary effort \u2014 including several Sea Grant\u00ad-funded studies \u2014 began with a rapid response.<\/p>\n\n\n\n “We virtually commandeered the Duke and UNC research vessels,” Hans Paerl, a Sea Grant researcher at the University of North Carolina’s Institute for Marine Sciences, recalls the days after Floyd hit.<\/p>\n\n\n\nSIGNALS AND CYCLES<\/strong><\/h2>\n\n\n\n
THE PAMLICO PUZZLE<\/strong><\/h2>\n\n\n\n