50 
Joshua Laerm, et al. 
from 0 to 1, with 0 indicating no species in common and 1 indicating all 
species in common. The river systems compared were the Suwannee 
River (from Fargo, Georgia to its junction with the Alapaha River); the 
Alapaha River (a Suwannee River tributary); the Withlacoochee River (a 
Suwannee River tributary); the St. Mary’s River, and the Satilla River. 
The values ranged from a minimum of .84 for the Withlacoochee to a 
maximum of .90 for the St. Mary’s. The Alapaha, Suwannee, and Satilla 
were intermediate, with resemblance values of .86, .86, and .88, respec- 
tively. These differences are due entirely to absence from the swamp of 
minnows, which otherwise are widely distributed in adjacent drainages. 
Their absence appears to be due to substantially lower pH values in the 
swamp. 
Swamp pH ranges from 3.1 to 4.2; pH values for surrounding 
streams (where minnows occur) range from 4.8 to 6.9. In a study of 
Carolina bay lakes in North Carolina, Frey (1951) noted that in two lakes 
with a pH of 4.3 there were no minnows, while lakes with higher pH 
values (up to 5.9) had some minnows present. These were Notropis 
chrysoleucas, N. chalybaeus, and N. petersoni — three of the species that 
occur near the Okefenokee Swamp. Comparing minnow distributions 
with pH shows that appearance of minnows in the St. Mary’s River coin- 
cides with a pH of 4.8 or higher. The pH values for surrounding streams 
are even higher. Although detailed pH data for these streams are not 
available (especially for the Suwannee River section) the general pattern 
suggests that increasing acidity might limit, or at least influence, minnow 
distributions. This possibility deserves more critical attention. 
Habitat Distribution of the Fishes 
The 36 species of fish occurring in the swamp are distributed in a 
heterogeneous series of aquatic habitats that can be broadly classified as 
lake, aquatic prairie, and stream. 
Lakes are open bodies of water of .25 ha or larger with depths of .5 
m or more. The bottom is generally unconsolidated peat, which may have 
a depth of .3 m to greater than 1 m; some lakes, however, have hard sand 
bottoms. The margins are heavily vegetated with rooted and floating 
aquatic plants as well as submergent vegetation. The topography around 
the lakes grades into aquatic prairie (when the water levels are not low) 
composed of a variety of rooted aquatic macrophytes, floating vegeta- 
tion, sedges, and small shrubs. Water depth may range from several cm 
to over 1 m. Current in these two areas varies from none in the lakes to 
noticeable in the prairies. Streams generally have noticeable to moderate 
current, consolidated banks, and sandy bottoms. Some aquatic vegeta- 
tion and backwater areas are at the water margins. 
The streams are located primarily in the northwest part of the 
swamp and on some of the islands. The prongs of the Suwannee River 
and the Suwannee Canal also provide stream habitat. Elements of the 
prairie habitat, i.e. heavily vegetated areas, can be found bordering lakes 
