Eutrophication in the Albemarle-Pamlico Sound System: Symptoms and Causes

Water quality in the Albemarle-Pamlico Sound system, one of the largest estuaries in the U.S., may be threatened by blue-green algal blooms, a symptom of eutrophication, Blooms have developed during some recent years in two of the Sounds´ tributary rivers, the Chowan and the Neuse, While there is general agreement that excess nitrogen (N) and phosphorus (P) nutrients lead to such blooms, the available evidence is not clear-cut as to 1) whether or not N and P in the affected rivers is higher than in other nearby unaffected tributaries, or 2) whether or not nutrients in the rivers have increased substantially over the past two decades. Current N and P loading rates from the tributary basins do not appear to be abnormally high. Recent research has shown that although nutrients in these rivers are sufficient for blooms to develop every summer, they do not, probably because year-to-year variations in river flow also play an important role in bloom formation.