DISTRIBUTION AND HABITAT USE BY DWARF CRAYFISHES (DECAPODA, CAMBARIDAE, CAMBARELLUS)

We examined distribution and habitat use by the dwarf crayfishes Camba rellus diminutus and C. shufeldtii in seven coastal drainages along th e Mississippi Gulf coast. Cambarellus shufeldtii occupied a wider coas tal geographic range than C. diminutus, with the latter species being restricted to eastern drainages. Cambarellus shufeldtii occurred in si tes that were less acidic and had lower relative abundance of emergent aquatic vegetation and more variable relative abundance of submerged aquatic vegatation than sites typically used by C. diminutus, The two species were not syntopic in any collections, although they co-occurre d in two of the drainages sampled. Both crayfishes were collected more frequently from oxbow side-ponds than from adjacent channel habitats. Oxbow side-ponds are characterized as less turbid than channels, warm , slow-moving, heavily vegetated, and having a bottom substratum cover ed with litter compared to adjacent channel habitats. Further, oxbow s ide-ponds were characterized by structurally complex submerged aquatic vegetation such as Myriophyllum aquaticum and Elodea canadensis, whic h may provide enhanced protection from predators. Dwarf crayfish body size coupled with macrophyte complexity and coverage may explain their disproportionate use of oxbow side-ponds compared to channel habitats . Oxbow side-ponds appear to be important habitats for dwarf crayfish in the coastal drainages in the northern Gulf of Mexico.