92 
Bruce L. Yeager 
METHODS 
Except for two collections from tributary reservoirs and one from 
Wilson Reservoir, medusae were taken in a 0.5-m-square beam net 
towed obliquely through vertically integrated strata at approximately 
1.0 m/s for 10 minutes (Graser 1977, Tuberville 1979). The method was 
used as a standard ichthyoplankton sampling procedure throughout the 
Tennessee River Valley. 
Samples were preserved in 10% formalin. In the laboratory, speci- 
mens of C. sowerbyi were sorted from the ichthyoplankton samples and 
transferred to 5% formalin buffered to ph 7.0. Specimens were donated 
to the Department of Zoology at the University of Tennessee. 
RESULTS AND DISCUSSION 
Incidental collections of medusae of freshwater jellyfish in ichthyo- 
plankton samples taken between 1978 and 1985 in the vicinity of Ten- 
nessee Valley Authority power projects yielded numerous additional 
records in Mississippi, Alabama, and Tennessee, and expanded the 
range of collections in the Tennessee River system (Table 1). Collection 
localities for medusae reflect efforts directed to specific sampling sites 
and do not necessarily define habitat for C. sowerbyi within the Tennes- 
see River system. 
Craspedacusta sowerbyi was present in seven mainstream impound- 
ments of the Tennessee River and in at least two tributary impound- 
ments, Norris and Douglas reservoirs. Historical records (Table 2) and 
those reported here (Fig. 1) extend over 394 miles of the Tennessee 
River, between river miles 136 and 530, and include all mainstream 
impoundments except Fort Loudon Reservoir, which has not been 
sampled with the types of gear likely to capture medusae. Collections 
from tributary rivers (exclusive of the Cumberland River localities) 
extend the records to include 673 river miles from the most downstream 
site on the Tennessee River to the most upstream sites on the French 
Broad and Clinch rivers. 
Craspedacusta sowerbyi is probably an exotic species introduced 
from the Orient (Kramp 1950) where it occurs in a system of standing 
and running waters along 1500 miles of the Yangtze River basin in 
China. First found in the United States in 1908, the medusae have been 
reported here only sporadically. Hydroids are associated with lotic, or 
running water, habitats (Hutchinson 1967), whereas medusae are most 
often found in lentic or standing waters, particularly artificially con- 
structed impoundments (Lytle 1960). The system of alternating riverine 
habitats and impoundments available in the Tennessee River system is 
conducive to the establishment or formation of both the hydroid and 
medusoid stages. 
