Reproductive biology of Palaemon gravieri (Decapoda: Caridea: Palaemonidae)

Breeding and recruitment patterns were described and analyzed in a population of Palaemon gravieri inhabiting wann-temperate waters of southern Korea. Breeding period was seasonal, beginning in March, peaking (89% ovigerous females) in May, and then ending by August. Females with embryos near hatching had ovaries filled with vitellogenic oocytes ready for new spawning, indicating successive spawning. Laboratory observations on females incubating embryos confirmed that they spawn again after incubated embryos hatch; the female then underwent a post-hatching molt and then never had further ovarian development and spawning, indicating that the female has just two broods per year. Breeding period was constrained by temperature, and release of larvae coincided with, a plankton bloom in the sampling area. Females reached sexual maturity and produced a brood in their first year, overwintered, and produced a brood again the following summer. Reproductive output (effort) of the female was rather high. No significant relationship was found between female size and embryo size. Embryo volume was relatively small, indicative of small amount of energy allocation to each embryo. Embryo loss during incubation was not high. Recruitment of juveniles was closely linked to the breeding period, beginning in July and ending in September. Reproductive life history traits for P. gravieri seem to be closer to stochastic (bet-hedging) models in which adults live in stable environments but in which juvenile (= larval) mortality is variable.