4 Million Fish Die in Pamlico River
On August 6, 2008 the largest fish kill on the Pamlico River in over a decade occurred between the Whichards Beach area and Broad Creek. Over 3.9 million fish, primarily juvenile menhaden were found floating within the channel and along the north side of the river.
Preliminary lab results from the State Division of Water Quality revealed an unnaturally high number of a toxic dinoflagellate called Karlodinium. This plant-like dinoflagellate releases a toxin, called Karlotoxin that damages the gills of fish, and can basically cause them to suffocate. Since the kill consisted of mainly juvenile menhaden, which are filter feeders, the death is more likely associated with the toxin. Low oxygen levels would have produced a kill with multiple species of fish, not just menhaden. Conditions appeared to have been ideal for the karlodinium organisms to bloom and out compete other species of algae. Karlodinium was also associated with a subsequent fish kill of close to 1000 menhaden on August 15 along the Washington Park waterfront.
Also in the water at the time of the kill was a bloom of blue-green algae, also known to be toxic at times. There is no indication that the toxin from Karlodinium is a human health concern. In North Carolina’s coastal waters, blooms of Karlodinium are rare.
Both species found at the fish kill are "nutrient-loving" - they thrive in nutrient over-enriched waters. The Karlodinium has caused only a few fish kills in North Carolina waters; it appears to be more active in the Chesapeake Bay. The last known fish kill by Karlodinium was in the Neuse River in 2006. That bloom was partly associated with high nutrient availability.
Research in the Chesapeake Bay has found a link between harmful algae blooms, that include Karlodinium, and mortality and lower spawning rates of oysters.
In 1989 the North Carolina General Assembly declared the Tar-Pamlico River to be Nutrient Sensitive. In simple terms, an excessive amount of nutrients, specifically nitrogen and phosphorus are entering our waterways reeking havoc on the natural balance of the river system. While nitrogen and phosphorus are natural elements normally found in aquatic ecosystems, human impacts to the land, air and water cause an imbalance that can lead to toxic algae blooms and ultimately fish kills. For example, nitrogen in the form of ammonia emitted to the atmosphere in large amounts from North Carolina’s more than 2000 industrial hog operations totaling 10 million animals will fall back to the land and water, typically within 100 miles of the source.
Human induced stressors, such as nutrient pollution, plays a significant role in the frequency and amounts of fish kills as well as the presence of lesions on fish. This summer season has seen a rise of fish kills in both the Pamlico and Neuse River estuaries. It is clear that the bloom of Karlodinium would not have been possible in the absence of high nutrient availability. Over enrichment of a waterbody by nutrients, also called eutrophication, leads to hypoxic conditions (i.e. little to no oxygen). The latest fish kills are a symptom of a much larger problem.
The state of North Carolina and the entire nation has the tools available to combat nutrient pollution. The steps completed to date along the Pamlico River aid in the battle to live sustainably with nature. However, the results we see in our estuarine waters indicate that much more needs to be done. Aggressively controlling polluted stormwater runoff; maintaining natural, tree lined buffers along all waterways; reducing sediment and nutrient loss from agricultural lands; eliminating hog lagoons and sprayfields and replacing with superior waste management technology are all critical elements that will aid in the restoration of a healthy Pamlico River. This in turn will enable us to maintain the level of economic stability we desire in eastern North Carolina, an economy that is strongly related to our coastal waters. The Pamlico-Tar River Foundation will continue to advocate for innovative change that enables us to move forward without harming the next generations’ opportunities to enjoy the river and utilize its many bounties.
Media Coverage of the Fish Kill
WITN-TV (8/25/08) WITN-TV (8/7/08)
Washington Daily News, Thursday Aug. 7, 2008 issue (no web link available)