MULTIPLE OVIPOSITIONS FROM SINGLE MATINGS IN THE MUD CRAB RHITHROPANOPEUS HARRISII

Ovigerous Rhithropanopeus harrisii were collected from the Neuse River estuary, North Carolina, at the beginning of the breeding season (April), and were individually maintained in the laboratory to determine the ability of the females to produce multiple egg masses and viable offspring from a single mating. Females were able to oviposit as many as four times without repeated matings. All egg masses were fertilized. The frequency with which crabs oviposited (20-31%) was not dependent upon the number of previous ovipositions, but the number of crabs that would spawn again diminished with each oviposition. Regardless of the number of times the crabs had previously spawned, there was no significant difference in the time required to spawn another egg mass, nor in the viability of larvae hatched from these egg masses. Fifteen to 19 days were required for crabs to spawn, incubate, and hatch a clutch of larvae. Hatching success and size declined after the first hatch because of the inadequate cementation of eggs to the pleopods in the laboratory. Crabs did not spawn following ecdysis. Females capable of multiple spawnings from a single mating permit both spatial and temporal dispersal of zoeae, thus decreasing the variance in the number of surviving offspring in the next generation. Multiple spawnings may also assure continued reproduction under stressful or hazardous conditions, when mating activity may be reduced.