Parí­¢metros populacionais e distribuição de Arenaeus cribrarius (Crustacea, Portunoidea), no litoral sudeste brasileiro

Abstract

To test the hypothesis of differential occupation of depths by demographic groups of A. cribrarius, their population structure, spatial-temporal distribution and sex ratio were studied, taking environmental factors into consideration. The animals were collected monthly during one year in Ubatuba, southeastern coast of Brazil, at nine different depths. There was no deviation from the pattern 1:1 sex ratio, and also no significant difference in size between the sexes. Reproductive activity was continuous, but more intense in the summer. It was possible to verify that there is differential occupation of space by demographic groups of A. cribrarius. Juveniles occupy shallower regions, which probably provide them with protection of predation. Adult males are more often collected in regions near these juveniles, probably in order to maximize the chances of finding primiparous females. Finally, adult females were more associated to deeper regions, where larval dispersal is facilitated by the influence of the movement of water mass.

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

“…Despite all these studies with A. spinimanus, nothing is known about the spatiotemporal distribution of its demographic groups. A differential spatio-temporal distribution for demographic groups has been reported for other swimming crabs such as Callinectes ornatus Ordway 1863 (Andrade et al, 2014), Callinectes danae Smith 1869 (Barreto et al, 2006 andAntunes et al, 2015) and Arenaeus cribrarius (Lamarck 1818) (Silva et al, 2018). In view of that, we believe that A. spinimanus also shows this pattern.…”

Assessing the factors driving the changes in the spatio‐temporal distribution of Hepatus pudibundus (Decapoda, Brachyura) over a 20‐year interval in a region under the influence of El Niño (ENSO)

“…(2014) and Silva et al. (2018), respectively. This station was characterized by a high proportion of silt + clay and high organic matter content, especially in the P2.…”

“…The recruitment period may have changed simply because it is strongly related to the reproductive period. Nonetheless, recruitment in winter could also be a strategy to decrease food competition with other crustaceans that inhabit Ubatuba Bay and are normally more abundant in spring and summer, such as the swimming crabs C. ornatus (Andrade et al., 2014) and A. cribrarius (Silva et al., 2018); the hermit crab Dardanus insignis (Saussure 1858) (Frameschi et al., 2015); and the majoid crab Leurocyclus tuberculosus (H. Milne Edwards & Lucas, 1834) (Bernardes et al., 2016). Thus, by avoiding confrontations with other species, the recruitment of H. pudibundus can be more effective and juveniles can develop faster.…”

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

“…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).…”

“…Temperature, salinity, sediment texture, occurrence of water masses, food availability and even the specific physiological needs of each life cycle phase can also modulate the ontogenetic distribution of brachyurans (Andrade et al ., 2015; Silva et al ., 2018; Theuerkauff et al ., 2018; Bernardo et al ., 2020). In this sense, we tested the hypothesis that there is differential occupation between the demographic groups of L .…”