Population structure, recruitment, and mortality of the freshwater crab Dilocarcinus pagei Stimpson, 1861 (Brachyura, Trichodactylidae) in Southeastern Brazil

Abstract

Freshwater crabs of the family Trichodactylidae are widely distributed in major river basins of the South American continent. The population structure of one species, Dilocarcinus pagei, was analyzed in an artificial reservoir in Southeastern Brazil, recording data on the sex ratio, recruitment, and mortality. A total of 1339 crabs were collected and included 804 males and 535 females (3 ovigerous and 4 with hatchlings); the sex ratio was 1:0.61 (males: females). Two modes of male and female carapace width (CW) were recorded, with means of 14.4 mm (n = 407) and 38.9 mm (n = 394) for males and 17.9 mm CW (n = 269) and 39.2 mm (n = 267) for females. The mean size of males (CW = 26.6 ± 13.8 mm) was significantly larger than that of females (CW = 28.5 ± 12.8 mm). The data indicated that recruitment occurs in summer (January–March), with the reproductive period in spring (October–December), periods with the highest rainfall and temperature values in the region. Reproduction leads to the death of the parents, influencing the sex ratio, which oscillates mainly during the reproductive period.

Keywords:

• crustacea
• reproduction
• juvenile recruitment
• ecology

Acknowledgments

The authors would like to thank to their colleagues at the UNIRP Zoology Department for their help during fieldwork. We thank Dr Janet W. Reid (JWR Associates) for editing the English text and anonymous reviewers for their valuable comments that improved the manuscript. All experiments conducted in this study complied with the current applicable state and federal laws in Brazil.

Disclosure statement

No potential conflict of interest was reported by the authors.