Reproductive aspects of prawn Desmocaris trispinosa (Aurivillius, 1898) from a periurban stream of Abidjan (Banco stream, Côte d'Ivoire)

Abstract

Abstract Aim Characterize habitats and determine the reproductive parameters of the prawn Desmocaris trispinosa (Aurivillius, 1898) from Banco stream, a periurban stream of Abidjan (Côte d'Ivoire, West Africa). Methods Sampling was conducted monthly, from July 2020 to June 2021 at four stations. Environmental characteristics were measured before prawn sampling. The sampling was made with a dipnet during five-minute active fishing conducted by a single operator at each station. Results According to environmental variables, sampling stations were divided into three groups: almost undamaged (B4), slightly disturbed (B1) and disturbed (B2 and B3). In total, 467 specimens of D. trispinosa were captured in which 127 males, 275 females and 65 juveniles. Overall, the sex ratio (1:2.1) was in favour of females. Considering stations, the sex ratio was also in favour of females. But, only in the almost undamaged station (B4), the difference was significant (χ2 = 70.20; P<0.001). At this station, a variation of sex-ratio was observed in two seasons. In total, 116 ovigerous females were analysed on all stations. Fecundity varies from 5 to 16 oocytes with an average of 11.03 ± 2.18. First maturity size was estimated at 4.82 mm carapace length for the combined data. Females from the station free from human activities (B4) reached sexual maturity (4.23 mm) before those of the other stations (4.97 in B1 and 5.70 mm in B2). D. trispinosa from Banco stream reproduces continuously year-round with two peaks in the rainy season. The oocyte volume was negatively influenced by temperature and positively by dissolved oxygen. Conclusions D. trispinosa reproduces year-round in undisturbed stations and reaches sexual maturity faster at these stations compared to disturbed stations. The sex ratio was in favour of females. Consequently, this species would be naturally polygamous.