Population structure and reproductive biology of Uca rapax (Decapoda: Ocypodidae) in a tropical coastal lagoon, southeast Brazil

Abstract

A population of the fiddler crab Uca rapax (Smith, 1870) found in Itaipu Lagoon, southeast Brazil, was sampled monthly from July 2006 to June 2007 in order to study population and reproductive features. The sex ratio of the population was statistically different from the expected (1:1) in almost every month, with a predominance of males. The reproductive cycle and the recruitment of juveniles were continuous, with two peaks. The fecundity ranged from 1.110 to 13.189 eggs (4.984 ± 2.493.8), not differing statistically among seasons. In contrast, the relative fecundity (F') and the reproductive intensity index (RII) were highest in the summer. Female size at the onset of sexual maturity was estimated as 6.1 mm and egg diameter ranged from 0.20 to 0.28 mm. The anthropogenic impact on the environment of Itaipu Lagoon probably had adverse effects on the local U. rapax population, as inferred by its low fecundity rates, early maturation age and biased sex ratio

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

“…Most tropical species either reproduce continuously throughout the year, or have a longer breeding season than species at high latitudes (Emmerson, 1994). Continuous reproductive activity, as observed in S. rectum, occurs in other species of mangrove crabs along the Brazilian coast (Leme & Negreiros-Fransozo, 1998;Cobo & Fransozo, 2000;Hirose & Negreiros-Fransozo, 2008;Costa & Soares-Gomes, 2009;Gregati & NegreirosFransozo, 2009). …”

Temperature influences the reproduction of fiddler crabs at the southern edge of their distribution

“…Fiddler crabs usually inhabit tropical and subtropical estuaries (Crane 1975). In such areas, these crabs usually exhibit continuous reproduction, probably due to the constancy of environmental conditions and resource availability throughout the year (Colpo & Negreiros-Fransozo 2004;Litulo 2005;Benetti et al 2007;Costa & Soares-Gomes 2009;Martins & Masunari 2013a). However, some fiddler crabs have extended their distribution and are able to inhabit temperate estuaries, but the conspicuous seasonality in these areas seems to shorten their reproductive period (Wolfrath 1992;Rodr ıguez et al 1997;Yamaguchi 2004;Hartnoll 2006;C esar et al 2007;Boa & Guerra-Garcia 2015).…”

Sampling technique affects the population structure assessments of fiddler crab Minuca vocator (Herbst, 1804) (Ocypodidae: Gelasiminae)

“…In tropical and subtropical mangroves, fiddler crabs usually exhibit continuous reproduction, probably due to the constancy of environmental conditions and resource availability throughout the year (Colpo and Negreiros-Fransozo, 2004;Litulo, 2005;Benetti et al, 2007;Costa and Soares-Gomes, 2009;Martins and Masunari, 2013). The data on ovigerous frequency obtained by CPUE corroborated the continuous breeding hypothesis in Itapanhau and Itamambuca.…”