Reproductive Plasticity in the Speckled CrabArenaeus cribrarius(Decapoda, Brachyura, Portunidae) Associated with a Population Decline

Reproductive and population traits of the swimming crab Achelous spinimanus (Crustacea: Decapoda) in an upwelling region in southeastern Brazil

“…In contrast to many other portunoid species, where females mature earlier than males (see Mantelatto and Fransozo, 1999a;Marochi et al, 2013), carapace width showed no sexual dimorphism. Other portunid crabs also show a similar maturation size between sexes, with males maturing earlier than females, including A. cribrarius (see Andrade et al, 2015b), Portunus sanguinolentus (Herbst, 1783) (Rasheed and Mustaquim, 2010) and Achelous spinicarpus Stimpson, 1871 (Pardal-Souza andPinheiro, 2013). Assuming that the mortality rate tends to be higher among adults, and that the sooner an animal reaches sexual maturity the sooner it can produce descendants (Haefner, 1990), the elimination of a molt cycle must be another adaptive strategy of A. spinimanus.…”

“…Andrade et al (2014) reported that the adult females of Callinectes ornatus (Ordway, 1863) migrate to areas farther from the coast to disperse their larvae, and few males with developed gonads follow them, remaining near the coast in order to ensure mating with primiparous females. For Arenaeus cribrarius (Lamarck, 1818), Andrade et al (2015b) observed that the population adjusted to new environmental conditions by changing from continuous reproduction to seasonal reproduction, which assured a better food supply for the Figure 5. Adjustment of the logistic equation indicating the maximum carapace width (MCW) for males and females of the swimming crab Achelous spinimanus, in which 50% of the crabs are mature according to the analyses of gonadal development.…”

“…Assuming that the mortality rate tends to be higher among adults, and that the sooner an animal reaches sexual maturity the sooner it can produce descendants (Haefner, 1990), the elimination of a molt cycle must be another adaptive strategy of A. spinimanus. Andrade et al (2015b) noted that estimates of the size at which gonad sexual maturity is reached, especially in the case of edible species, are among the most important sources of information for understanding the biology and conservation requirements of a population. These authors also noted that reproductive activity may be related not only to seasonal variations of temperature or other environmental factors, but also to adaptive synchrony between the most intense periods of larval release and greater food availability.…”

“…These authors also noted that reproductive activity may be related not only to seasonal variations of temperature or other environmental factors, but also to adaptive synchrony between the most intense periods of larval release and greater food availability. Thus, the strategy in which females reach maturity at larger sizes may be ideal for maximizing their reproductive success, guaranteeing that more larvae will survive (Andrade et al, 2015b).…”

Population structure of the swimming crab Achelous spinicarpus (Crustacea, Portunoidea) in São Paulo northern coast, Brazil

“…However, the absence of difference between the mean males and females sizes reveals that, for A. spinicarpus, size cannot be considered as an indication of sexual dimorphism. Such pattern is not common for Brachyura, since size difference has already been related in Southeastern Brazilian coast (Bertini et al, 2010b;Almeida et al, 2013;Silva et al, 2014;Andrade et al, 2015c). However, a different pattern was also observed by Ogawa and D'Incao (2010) for A. spinicarpus, who collected samples from 10 to 100 m in depth and described females with mean sizes larger than males.…”