Modulating factors of the abundance and distribution of Achelous spinimanus (Latreille, 1819) (Decapoda, Portunoidea), a fishery resource, in Southeastern Brazil

Abstract

This is the first study to examine how different environmental factors may influence the distribution of swimming crab Achelous spinimanus across geographically distant and distinct habitats. We analyzed the influence of bottom water temperature and salinity, sediment texture and organic matter content on the spatiotemporal distribution of A. spinimanus. The crabs were collected from January 1998 until December 1999 by trawling with a shrimp fishing boat outfitted with double-rig nets. The sampling took place in Ubatumirim (UBM), Ubatuba (UBA) and Mar Virado (MV) bays, located in the northern coast of São Paulo State (Brazil). These three bays were chosen as they differed in many physiographic features. We captured 1,911 crabs (UBM = 351; UBA = 1,509; MV = 51), and there were significant differences in abundance between bays and between stations. The distribution of A. spinimanus was primarily associated with sediment features: abundance was higher in stations with sandy sediments classified as gravel, very coarse sand, and intermediate sand. Portunoidea usually burrow in the sediment for protection against predators and to facilitate the capture of fast prey. In addition, the station with the highest abundance of A. spinimanus was also naturally protected from fishing activities, and composed of heterogeneous sediment, in terms of grain size. Hence, the combination of a favorable sediment heterogeneity and protection from fishery activities seemed to be effective modulators of the abundance and distribution of A. spinimanus in these bays.

Unveiling the dynamics of the spider crab Libinia ferreirae, through reproductive and population characteristics on the south-eastern coast of Brazil

“…Sexual dimorphism with larger males than females seems to be a common pattern for crustaceans, including brachyurans and crayfishes (Miazaki et al ., 2019; Sousa et al ., 2019; Bernardo et al ., 2020; Hamasaki et al ., 2020). According to Hartnoll (1969), males are larger because they tend to protect pre- and post-moulting females with the copulatory embrace, representing an adaptation to ensure reproductive success.…”

“…The identification of juvenile specimens based on the abdominal condition (sealed or not) has been widely used for Portunoidea (e.g. Taissoun, 1969; Williams, 1974; Silva et al ., 2017; Sousa et al ., 2019) and is useful for the representatives of the superfamily Majoidea. Four demographic groups were used in the analyses: juvenile males and females (J), adult males (AM), non-ovigerous adult females (AF) and ovigerous females (OF).…”

“…The population dynamics of crustaceans can be addressed through several aspects, e.g. frequency distribution of individuals in size classes, reproductive period, recruitment, differential distribution of demographic groups and sex ratio (Garcia & Mantelatto, 2001; Chan & Williams, 2004; Andrade et al ., 2014, 2017; Silva et al ., 2018; Bernardes et al ., 2019; Sousa et al ., 2019).…”

Environmental factors modulating the bathymetric distribution of the demographic groups of Achelous spinimanus (Crustacea)

“…Achelous spinimanus has already been studied by other researchers. For instance, in the Ubatuba region (SP) Santos et al (1994Santos et al ( , 2000, Lima et al (2014) and Sousa et al (2018) studied its ecological distribution, and Santos and Negreiros-Fransozo (1999) its reproductive cycle. Branco and Lunardon-Branco (2002) reported its trophic ecology in Armação do Itapocoroy, Penha (SC).…”

Reproductive biology of the swimming crab Achelous spinimanus (Decapoda, Portunoidea): a potential fishing resource

“…Exploitation of the meat and byproducts of A. spinimanus for economic uses is increasing in Brazil, as also in other countries since 1999 (FAO-Globefish, 2007). The size and taste of this swimming crab makes it suitable for human consumption (Santos et al, 1995;Branco et al, 2002;Sousa et al, 2018).…”