Comparação da estrutura populacional das espécies de Uca (Crustacea: Decapoda: Ocypodidae) no Manguezal de Itacuruçá, Rio de Janeiro, Brasil

Abstract

Este trabalho foi realizado no Manguezal de Itacuruçá, na Baía de Sepetiba com o objetivo de analisar a estrutura populacional das espécies de Uca Leach, 1814. Foram realizadas coletas de junho/2005 a maio/2006, durante as marés baixas. Os caranguejos foram capturados manualmente por duas pessoas e durante 15 minutos. Um total de 2580 animais foi coletado, sendo 1465 machos e 1115 fêmeas. Com relação ao tamanho dos indivíduos, observou-se que os animais do Manguezal de Itacuruçá, de maneira geral, apresentam tamanhos menores que os encontrados em outros manguezais do Brasil. Contudo, os machos atingiram tamanhos maiores do que as fêmeas. A distribuição de freqüência em todas as classes de tamanho foi unimodal para a maioria das espécies, com exceção de U. thayeri Rathbun, 1900 e U. vocator (Herbst, 1804), as quais não apresentaram um padrão definido. Os machos foram mais abundantes em todas as classes de maiores tamanhos. A razão sexual diferiu significativamente da proporção 1:1, estando deslocada para uma maior freqüência de machos, com exceção de U. thayeri e U. victoriana von Hagen, 1987, as quais tiveram predominância de fêmeas.

Temporal distribution in the abundance of the fiddler crab Uca (Leptuca) uruguayensis Nobili, 1901 (Decapoda: Ocypodidae) from Garças River mangrove, Guaratuba Bay, southern Brazil

“…The unimodal distribution of CW classes for both sexes in the present study was different from the population of Rio de Janeiro State coast where a bimodal distribution for females was recorded (modal CW classes in 5.0 to 6.0 mm and in 7.0 to 8.0 mm) (Bedê et al, 2008). These authors explained this exceptional feature as a consequence of the small number of female samples (n = 24).…”

“…The sex ratio found in this study (1:1) is in accordance with César et al (2005) with the population from Samborombón Bay, Argentina, but different from that found by Bedê et al (2008) in the mangrove of Itacuruçá, Brazil (1:0.42) and from Mar Chiquita, Argentina (1:1.68) (Spivak et al, 1991).…”

“…On the other hand, males can grow continuously attaining larger size for courtship purposes (Warner, 1967;Adiyodi and Adiyodi, 1970;Wenner, 1972;Christy and Salmon, 1984;Díaz and Conde, 1989;Henmi and Kaneto, 1989). This observation was also reported by Bedê et al (2008) in the population of U. (L.) uruguayensis from Rio de Janeiro State coast.…”

“…The population of the Guaratuba Bay is composed of the smallest individuals (males 2.33 to 8.33 mm, non-ovigerous females 2.52 to 7.79 mm and ovigerous females 5.05 to 6.95 mm). The population from Itacuruçá mangrove, Rio de Janeiro, measured 4.57 to 12.00 mm (males) and 5.00 to 10.86 mm (females) (Bedê et al, 2008), from Indaiá River mangrove, São Paulo, measured from 4.18 to 11.60 mm (males) and 3.90 to 9.80 mm (females) (Hirose et al, 2012), and from Argentina, maximum CW values measured were 14.47 mm (males) and 13.43 mm (females) (Spivak et al, 1991) and 14.10 mm (males) and 12.00 mm (females) (Hirose et al, 2012). Differences in food availability seem to be the main cause for this strong CW discrepancy among populations from different localities (Colpo and NegreirosFransozo, 2004).…”

Population biology and morphometric sexual maturity of the fiddler crab Uca (Uca) maracoani (Latreille, 1802) (Crustacea: Decapoda: Ocypodidae) in a semiarid tropical estuary of northeastern Brazil

“…However, it is possible to find populations of crustaceans with significant deviations from the expected proportion of 1:1, which can be caused by differences in birth rates or mortality rates between the sexes (Johnsson, 2003) and/or the sampling rates (Montague, 1980). Historically, some Uca populations have been recorded with significant deviations from the fisheries proportion (Wolf et al, 1975;Frith & Brunenmeister, 1980;Colby & Fonseca, 1984;Spivak et al, 1991;Emmerson, 1994;Litulo, 2005a;Bedê et al 2008). In the present study, the sex ratio was skewed towards males, in a proportion of 3.5:1 (Table 3).…”