Continuous reproduction and episodic recruitment in nine shrimp species inhabiting a tropical seagrass meadow

Abstract

Breeding and recruitment patterns were analysed and compared in a group of nine caridean shrimp species from seagrass meadows in a tropical locale, Puerto Rico. Embryo production took place throughout the year in populations of all species. No multispecies pattern in breeding intensity was detected. Most females sampled that carried embryos near hatching also had an ovary filled with vitellogenic oocytes ready for a new spawning. Laboratory observations on females incubating embryos confirm that they spawn again after incubated embryos hatch and the female undergoes a posthatching molt. Median period of embryo incubation ranged from 5–10 days in females of eight species maintained in the laboratory. Reproduction thus appears to be continuous in these tropical shrimps, with females producing successive broods at short intervals after they reach maturity. Increases and decreases in the smaller size classes of species size-frequency distributions suggest that recruitment intensity was variable throughout the year of sampling. Most importantly, the monthly highs and lows of recruitment strength were concordant among species with no apparent seasonal pattern. Given that larval production was continuous, the episodic recruitment pattern observed indicates that similar environmental (mortality) factors acted simultaneously on either the planktonic larvae or newly recruited juveniles of all species.