Population biology of the burrowing crab Neohelice granulata, (Crustacea: Decapoda: Varunidae) from a tropical mangrove in Brazil

Abstract

ABSTRACT. The population biology of the burrowing crab Neohelice granulata (Dana, 1851) from a mangrove in Jabaquara Beach, Paraty, state of Rio de Janeiro, Brazil (23º13'04"S and 44º42'47"W), was studied with respect to the following traits: size-frequency distribution, recruitment, reproductive period, fecundity, and sex ratio. Specimens were sampled monthly from April, 2003 to March, 2004, at the river margins during low tide periods. Size, sex, presence of eggs, and stage of the female gonad were recorded. Ovigerous females had their eggs removed and counted. The reproductive period was continuous and the highest frequency of ovigerous females was recorded in the fall and winter. Mature gonads were found throughout the year and recruitment was continuous but more intense during the summer. The fecundity of N. granulata (30028.3 ± 10861.2 eggs) was high in comparison to studies in other localities. In general, the proportion of males was similar to that of females (1:0.92); however, males were predominant in the fall (1:0.77) and winter (1:0.75). All the information available so far on the reproduction of N. granulata involves populations from subtropical salt marshes; therefore, comparative studies including other habitats, such as mangrove forests, are needed to further understand the environmental influences on the population and reproductive biology of semiterrestrial crabs.

Biología poblacional del cangrejo de manglar <i>Ucides cordatus</i> (Decapoda: Ucididae) en un estuario tropical semiárido

“…According to these authors, in U. cordatus the dominance of individuals of intermediate and larger sizes is common in populations with greater longevity. This pattern has also been described in other crab species (Leme, 2002;Gregati & Negreiros-Fransozo, 2009;Hartnoll et al, 2009).…”

“…This distribution pattern has been observed for other crab species (Thurman, 1985;Díaz & Conde, 1989;Spivak et al, 1991;Cobo, 2005;Litulo, 2005;Castiglioni et al, 2006;Gregati & Negreiros-Fransozo, 2009;, as well as for U. cordatus (Diele et al, 2005). A unimodal distribution suggests a stable population with constant mortality and recruitment rates (Litulo, 2005).…”

“…Population parameters of brachyuran crabs have been investigated by analyzing the distribution of individuals in size class, sex ratio, range in size at sexual maturity, reproductive cycle, fecundity, and juvenile recruitment (Thurman, 1985;Díaz & Conde, 1989;Flores & Negreiros-Fransozo, 1999;Conde et al, 2000;Cobo, 2005;Litulo, 2005;Benetti et al, 2007;Bezerra & Mathews-Cascon, 2007;Kassuga et al, 2008;Gregati & Negreiros-Fransozo, 2009;Hartnoll et al, 2009;Araújo et al, 2012).…”

“…After birth, many factors can affect this relationship, such as mortality rates, longevity and growth, predation, migration, utilization of different habitats by two sexes (Wenner, 1972;Hartnoll et al, 2009), and processes related to reproductive events (Gregati & Negreiros-Fransozo, 2009). …”

Population dynamics ofSesarma rectum(Crustacea: Brachyura: Grapsidae) in the Ariquindá River mangrove, north-east of Brazil

“…The population structure of mangrove crabs has been analysed mainly with regard to the distribution of individuals by size-classes, comparing the body size of males and females, age distribution, proportion of males and females, recruitment and the reproductive period (Díaz & Conde, 1989; Castiglioni et al , 2006; Nicolau & Oshiro, 2007; Silva et al , 2007; Hirose & Negreiros-Fransozo, 2008; Costa & Soares-Gomes, 2009; Gregati & Negreiros-Fransozo, 2009). This information about populations adds to the knowledge of the ecological stability of species in a given habitat, and leads to greater understanding of their biology.…”