Reproductive traits of two crangonid shrimps, Crangon hakodatei and Metacrangon sinensis (Crustacea, Decapoda) in the Geoje Island, South Korea

Abstract

Fecundity of two crangonid shrimps, Crangon hakodatei and Metacrangon sinensis, were examined. Despite their essential ecological role, two crangonid shrimps’ fecundity is barely known. Various parameters were used to define fecundity; number of eggs, reproductive output, egg dry weight and egg size. As fecundity is considered as one of the fundamental elements to understand species reproductive strategies, comparisons were made afterwards. Ovigerous females of Crangon hakodatei (7.15-17.84 mm CL) carried 738 to 10,238 eggs per brood, whereas Metacrangon sinensis females (3.69-7.45 mm CL) carried 8 to 38 eggs per brood. The number of eggs varied according to the body size in both early and late stages of egg development. The reproductive output (RO) of C. hakodatei was 0.16 in average, based on dry weights in early eggs, whereas M. sinensis had average value of 0.14. Brood mortality, which is a common phenomenon in crustaceans, was independent of female size and estimated to be a 38.43%. However, it was observed that brood loss did not occur during the incubation period in M. sinensis; perhaps due to small sample size. Mean egg volume and length significantly increased from non-eyed to eyed egg stages in both species. On the other hand, mean dry weight of eggs decreased as it alters from non-eyed to eyed stage. As reflected by the different egg numbers and size, their reproductive strategies are obviously opposed. Examining these two shrimps’ fecundity would ultimately expand our understandings of the diversity of reproductive strategies found in the family Crangonidae.