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

Salise Brandt Martins,Setuko Masunari

doi:10.1590/s0104-64972013000200003

Abstract

A study on the temporal distribution, sex ratio, reproductive period, recruitment of juveniles and size composition of individuals of the fiddler crab Uca (Leptuca) uruguayensis was carried out in a population living in the Garças River mangrove, Guaratuba Bay, Paraná State, Brazil. Eight square samples of 0.25 m² (0.50 m side) were obtained on a monthly basis, from April/2011 to March/2012. The crabs were collected through the excavation of burrows and their carapace width (CW) was measured. Air and water temperatures varied from 19.0 to 29.5ºC and 17.0 to 27.0ºC, respectively, the salinity from 7 to 23 and the soil temperature from 19.0 to 29.2ºC. A total of 1,099 fiddler crabs were collected, being 529 males, 520 females (of these, 9 ovigerous) and 50 sexually undifferentiated individuals. The average density of the population ranged from 12 (June/11) to 71 ind.m-² (May/11), but its annual fluctuation was not correlated to abiotic variables. The sex ratio was 1:1 all year round and in all CW classes. Although in low abundance, ovigerous females were recorded in six months and juvenile crabs were present all year round, indicating a continuous reproduction and recruitment of the species. The CW of males ranged from 2.33 to 8.33 mm and that of females, from 2.52 to 7.79 mm: these data showed that this population is composed of smallest individuals among those studied

Highlights

Uca (Leptuca) uruguayensis Nobili, 1901 is one of the ten species of fiddler crabs recorded in Brazil (Bezerra, 2012)
Many aspects have been investigated on the populations of U. (L.) uruguayensis from c Published by Brazilian Crustacean Society, Ribeirão Preto, Brazil - December 2013 different localities: abundance, distribution, population structure, fertility, life history, reproductive period, sex ratio and sexual maturity (Branco, 1991; Spivak et al, 1991; Oshiro et al, 1998; César et al, 2005, 2007; Costa et al, 2006; Bedê et al, 2008; Hirose et al, 2012)
This paper aims to describe the temporal oscillation of density and population structure of U. (L.) uruguayensis during a period of twelve months, in the Garças River mangrove, Guaratuba Bay, Paraná State, Brazil

Summary

Introduction

Uca (Leptuca) uruguayensis Nobili, 1901 is one of the ten species of fiddler crabs recorded in Brazil (Bezerra, 2012). It is distributed in Western Atlantic, from Rio de Janeiro (Brazil) to the mouth of the Quequén River in the province of Buenos Aires (Argentina) (Boschi, 2000). (L.) uruguayensis from c Published by Brazilian Crustacean Society, Ribeirão Preto, Brazil - December 2013 different localities: abundance, distribution, population structure, fertility, life history, reproductive period, sex ratio and sexual maturity (Branco, 1991; Spivak et al, 1991; Oshiro et al, 1998; César et al, 2005, 2007; Costa et al, 2006; Bedê et al, 2008; Hirose et al, 2012). The population from Paraná State is still poorly known: only Masunari (2006) described the spatial distribution and abundance of this fiddler crab along a salinity gradient within the Guaratuba Bay, and Martins and Masunari (2013), the relative growth of a population living in the mangrove of the Garças River, within the mentioned bay.

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