Recent Changes in the Freshwater Molluscan Fauna 
of the Greenfield Lake Basin, 
North Carolina 
William F. Adams 
Environmental Resources Branch 
United States Army Corps of Engineers 
P.O. Box 1890, Wilmington, North Carolina 28402 
ABSTRACT . — The molluscan fauna of the Greenfield Lake basin has 
undergone significant changes in recent years. In surveys conducted 
from January 1984 through October 1987, 16 species of mollusks were 
found in the basin. Twelve of those species were recorded from the 
basin for the first time; 15 species previously recorded in the basin 
were not found. The most noticeable change was the almost total 
elimination of the Unionidae. Changes in the molluscan fauna of the 
Greenfield Lake basin have probably been caused by a combination of 
factors and events. Those agents of change are still at work today and 
undoubtedly keep the molluscan population of the lake from ever 
establishing any type of equilibrium. Partial winter drawdowns are 
believed to be the most damaging aspect of the water management 
presently undertaken in the watershed. Pollution from non-point 
sources has probably also played a role in changing the fauna. 
Mollusks in Greenfield Lake, in Wilmington, New Hanover Co., 
N.C., were frequently sampled by malacologists during the early part of 
the twentieth century. Records of those collections are scattered in the 
literature, but a comprehensive survey of the fauna has never been 
undertaken. 
Because of its prominence in the literature of freshwater malacology 
on the south Atlantic slope, any changes in the molluscan fauna of 
Greenfield Lake are of general interest. Because of the available data on 
prior species occurrence, a comprehensive survey was undertaken to 
assess what changes have taken place in the composition of the lake’s 
molluscan fauna. 
Many of the taxa cited in this paper are in need of systematic 
revision. Resolving taxonomic problems was not a purpose of this 
study, but the subject has to be addressed because of the abundance of 
synonyms for some species and the revisions that have taken place since 
the time of the first Greenfield Lake records. A synonymy section has 
therefore been included to deal with this problem to the level necessary 
Brimleyana 16:103-117, July 1990 
103 
