Distribution and habitat use by dwarf crayfishes (Decapoda: Cambaridae:Cambarellus)

Abstract

We examined distribution and habitat use by the dwarf crayfishesCambarellus diminutus andC. shufeldtii in seven coastal drainages along the Mississippi Gulf coast.Cambarellus shufeldtii occupied a wider coastal geographic range thanC. diminutus, with the latter species being restricted to eastern drainages.Cambarellus shufeldtii occurred in sites 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 byC. diminutus. The two species were not syntopic in any collections, although they co-occurred 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 covered with litter compared to adjacent channel habitats. Further, oxbow side-ponds were characterized by structurally complex submerged aquatic vegetation such asMyriophyllum aquaticum andElodea canadensis, which 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.