18 
Charles K. Biernbaum 
a southern species, having been reported from Georgia and Florida west 
to Louisiana and southern Arkansas (Williams 1970, 1972; Fleming 
1972). Caecidotea forbesi is widespread east of the Mississippi River, 
with the exception of the Gulf coastal region (Williams 1970, 1972; 
Fleming 1972). Williams (1970) has previously reported the occurrence 
of C. forbesi in Anderson County, S.C. It is interesting that there 
appear to be correlations between the geographical distribution of C. 
laticaudata and A. forbesi and their respective seasonal occurrences at 
the refuge (Table 2). The northerly occurring C. forbesi is most common 
during cool seasons (March-May), whereas the southern species, C. 
laticaudata , is most common in summer. Lirceus lineatus was originally 
described by Say (1818) from Berkeley County, S.C. It is widespread 
east of the Mississippi River from the Great Lakes through the Gulf 
coastal region (Hubricht and Mackin 1949, Williams 1972). The oniscoid 
Armadillidium vulgare is cosmopolitan. Kelley (1978) reported A. 
vulgare from Aiken and Charleston counties, S.C. Porcellionides floria 
has been recently described by Garthwaite and Sassaman (1985) from 
the southern and western United States, Mexico, and the Bahamas. Its 
presence at the refuge constitutes its northernmost documented occur- 
rence in the eastern part of the country. Miktoniscus halophilus ranges 
from Massachusetts to Georgia (Schultz 1975, 1976), but it has not been 
previously reported from South Carolina. 
Amphipods 
Three amphipod species were collected in the refuge. Two species 
(Hyalella azteca and Crangonyx richmondensis richmondensis ) were 
common, whereas one species (C. serratus) was rare. Crangonyx serratus 
was collected only in winter in one unit, Dingle Pond (Table 4). No 
brooding females of this species were encountered. Fox (1978) reported 
all three species from the state. 
The most widespread and abundant amphipod was H. azteca , 
which reached high densities in practically all types of aquatic habitats. 
Although common throughout the year, examination of its degree of 
dispersion throughout the refuge (Table 5) and its abundance where it 
was found (Table 6) indicates that populations in many habitats were 
reduced during two periods. The first was a notable reduction in winter. 
The second was in mid-to-late summer, when two important environ- 
mental changes were evident. One was progressive drying out of many 
habitats that were flooded during the spring peak in abundance of the 
species. Another change in some locations having very dense growths of 
aquatic vegetation was apparent deterioration in water quality, as 
evidenced by abundant flocculent material in the water, the formation 
of an organic film on the surface, and occasionally the odor of hydrogen 
