Branchiopod and Malacostracan Crustaceans 
9 
Fig. 1. Map showing sampling areas, Santee National Wildlife Refuge, S.C. 
The four units of the refuge are managed primarily for waterfowl. 
Consequently, extensive complexes of water impoundments with 
connecting ditches have been constructed on these sites. These impound- 
ments vary in size, but a majority are 1 to 2 ha in size and quite shallow, 
with most being virtually covered in summer with such rooted vegetation 
as lilies or lotus. Other aquatic habitats occurring in the refuge are small 
borrow pits and shallow swamps, some bordering the lake and others 
found as isolated forest depressions. 
There are significant seasonal variations in the amount of water 
present in these aquatic habitats. The water level in Lake Marion is 
reduced prior to spring in anticipation of increased runoff farther up the 
Santee basin. As a result of such runoff, coupled with increased local 
rainfall, water levels in the refuge are high in the spring, except for some 
isolated habitats when spring rainfall is minimal. Usually, spring water 
levels become so high that substantial areas of forest are also flooded, at 
times up to 0.5 m in depth. Water levels then drop during summer and 
fall, frequently resulting in the total drying-out of some impoundments, 
ditches, and swamps. 
At any one time, temperatures of aquatic habitats at the refuge are 
highly variable because of differences in water depth and degree of 
shading. The highest water temperature recorded during the study was 
