Reproductive biology of the ghost crab, Ocypode rotundata Miers, 1882 (Decapoda, Ocypodidae) at Qeshm Island, Persian Gulf

Abstract

Abstract This study aimed to investigate some key aspects of the reproductive strategy of Ocypode rotundata Miers, 1882 from southwest beaches of Qeshm Island, Persian Gulf, Iran, by providing information regarding its sex ratio, sexual maturity, spawning period and fecundity. Samples were taken monthly, from February 2015 to January 2016. Size at the onset of morphometric maturity was estimated at 38.57 mm carapace width. The overall sex ratio (males/females) was observed as 1.13 : 1.00. On monthly based analyses, the sex ratio showed no significant differences, although a significant deviation was observed toward males in the larger size classes. According to the gonadosomatic index (GSI), gonad maturity and occurrence of ovigerous females, the main breeding season occurs from March to October, with a remarkable peak in June. Fecundity ranged from 24 152 to 10 5287 eggs per individual, with a mean value of 52 389 ± 25 660. The ratio between fecundity and carapace width varied from 632 to 2044 eggs/mm (mean: 1198 ± 472 eggs/mm) and fecundity relative to total mass varied from 771 to 1965 eggs/g (mean: 1336.66 ± 425.43 eggs/g). The reproductive output ranged from 1.04 to 3.78 (mean: 2.35 ± 0.90). The shape of the egg was spherical and it included 6 stages of growth, ranging from fully filled with yolk to fully occupied by the embryo. We concluded that reproduction in O. rotundata is seasonal, and that spawning occurs in an appropriate period to ensure maximum survival of the offspring. The fecundity of O. rotundata is higher than that of other species of Brachyura, with GSI variations being related to temperature. Overall, the results of this study provide relevant information for the reproduction in general and the breeding seasons of O. rotundata, whicht can be useful for conservation and management policies aimed at preserving the biodiversity of ghost crabs along the Persian Gulf’s sandy shores.