OCCURRENCE, REPRODUCTION, AND POPULATION GENETICS OF THE ESTUARINE MUD CRAB, RHITHROPANOPEUS HARRISII (GOULD) (DECAPODA, PANOPIDAE) IN TEXAS FRESHWATER RESERVOIRS

The mud crab, Rhithropanopeus harrisii has been found in 10 freshwater impoundments in Texas. Breeding populations were confirmed in eight of these reservoirs by the presence of gravid females, juvenile crabs, and zoeae in the plankton. Salinities varied from a low of 0.5 at Tradinghouse Creek Reservoir to a high of 3.0 at Lake Colorado City. A salinity of 0.5 is considerably below that reported previously for larval survival. Crabs were induced to breed in the lab at a salinity of 1.9 and hatching occurred at salinities as low as 0.5. DNA sequencing of the mitochondrial cytochrome c oxidase I (COI) gene for four reservoir populations revealed the presence of genetic structure and differences in levels of genetic diversity between reservoirs. Potential mechanisms of introduction are addressed.