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The influence of temperature on sex determination has been reported previously on many crustaceans. The interpretability of temperature capability to regulate the steroidogenic pathway, which in turn governs the offspring sex of mud crab, still remains unclear. Thus, the aim was to determine the effects of temperature on sex percentage and steroidal pathway in purple mud crab, Scylla tranquebarica. In sex percentage analysis, the eggs (28°C and 30°C), larvae (28°C, 30°C and 32°C) and juveniles (26°C, 28°C, 30°C) were exposed to different temperatures. The results revealed that exposure to a higher temperature during larvae (32°C) and juvenile (30°C) stages probably initiated the maleness (58.7%) and femaleness (60.8%) mechanism respectively. In steroid hormone analysis, the eggs (26°C, 28°C, 30°C and 32°C), larvae (29°C, 30°C, 31°C and 32°C) and juveniles (26°C, 28°C, 30°C and 32°C) were exposed to different temperatures. The steroidal assay corroborated the results of the sex percentages, which found higher dihydrotestosterone (172.4 pg/g) and testosterone (580.2 pg/g) levels when the larvae were incubated at a higher temperature (32°C) while higher estrone (136.9 pg/g) and estradiol (540.7 pg/g) levels when the juveniles were reared at high temperature (30°C). In brief, the temperature plays a significant role to redirect the mud crab sex during the larval and juvenile stages. [ABSTRACT FROM AUTHOR]

Interest in the production of crustacean aquaculture has focussed primarily on mud crab species; however, mud crab production still relies on wild‐caught juveniles due to the low production of viable seeds of mud crab. Thus, the aim of this study was to enhance mass propagation of purple mud crab seed by studying the relation of temperature on growth performance of the early life stage of purple mud crab. Several data such as survival, incubation duration and morphometric measurements were evaluated after temperature was exposed on the egg, larval and crablet stages. For the egg stage, high hatching success (78.95% and 75.00%) was noted within a limited temperature range (28°C and 30°C respectively). Also, significant increment of final egg diameter (0.33 ± 0.05 mm) after the berried crab incubated at 30℃. For larval stage, the highest survival rate was found when the larvae were reared at 30℃ and 31°C with 68.79 ± 2.69 and 66.98 ± 2.63% respectively. The largest morphometric measurements for megalopa (CW: 2.80 ± 0.15 mm) and C1 (CW: 2.86 ± 0.12 mm) were observed at 31℃. The yielded total juvenile at the end of the larval experiment indicated the highest production was obtained for temperature 31°C (1,095 ± 47.3 individuals) followed by 30°C (1,002 ± 84.7 individuals). For the crablet stage, the crablets were able to survive in a wide range of temperatures (26°C–32°C) with >95% survival; however, the temperature 26℃–29°C indicated larger morphometric measurements (CW: 6.24–6.39 mm). In brief, the optimal temperature for egg, larval and crablet stages was recommended within 28℃–30℃, 30℃–31℃ and 26℃–29℃ respectively. [ABSTRACT FROM AUTHOR]

Keywords: egg; juvenile; larva; mud crab; temperature EN egg juvenile larva mud crab temperature 707 713 7 01/07/22 20220201 NES 220201 INTRODUCTION A series of morphological variations started in early juvenile as an adaptability process to ensure the capability of mating and reproducing during adulthood (Parvizi et al., 2017). If sexual dimorphism occurred, the line between male and female is widening with the course of juvenile growth gl Copulatory organs, chelae, and abdomen can be used to differentiate between male and female juveniles. The traits of large chela in male crabs are considered to be evolved due to intra-sexual selection, in which the male crabs fight aggressively to access the female crabs (Yoshino et al., 2011). Most findings of brachyuran crabs applied the abdominal width as secondary characters to define the sexual maturity of female crabs (Waiho et al., 2016a; 2016b). [Extracted from the article]