Estructura de la población del cangrejo rojo de manglar, Goniopsis cruentata (Decapoda: Grapsidae) bajo diferentes impactos de pesca: Implicaciones para la gestión de los recursos.

Abstract

Abstract:The red mangrove crab, Goniopsis cruentata, influences the recruitment and composition of plant species in the mangrove ecosystem and it is an important fishery resource. Nevertheless, no current management and conservation plans are available for this species for the Brazilian coast. This investigation evaluated the population structure and reproductive biology in populations of G. cruentata under contrasting fishery pressures. The sampling program was carried out in two mangroves, Vaza-Barris and Sergipe River, from January through December 2011. Crabs from both mangroves were randomly collected by a professional fisherman during daytime low tide periods, using a fishing rod baited with pieces of a locally abundant gastropod, Pugilina morio, during 20min/area (catch per unit effort). Monthly measurements of air, sediment surface layer and water temperatures were obtained with a digital thermometer and salinity with an optical refractometer. Both crab populations were compared concerning their abundance, body size, sex ratio, size at onset of sexual maturity and fecundity (FI). Abiotic factors (air, water and mud temperature; and salinity) showed no significant differences between sampling localities. A total of 4 370 crabs were sampled, 2 829 from the Sergipe River and 1 541 from the Vaza-Barris River. The abundance and body size of crabs were compared between mangroves, and statistically significant differences were found. The sex ratio for both populations differed from the expected 1:1 ratio, and a significant deviation in favor of juvenile males was obtained, while adults showed a bias toward females. The estimated size at onset of sexual maturity for both sexes was similar in both populations. However, the populations differed significantly in the number and volume of eggs: a higher FI was obtained in females from the Sergipe River, while a higher egg volume was observed in females from the Vaza-Barris River mangrove. These results indicated a tendency to decrease the body size, the abundance of crabs and the reproductive potential of the species, with higher fishing intensities, reinforcing the need to develop a management plan as well as to establish conservation units for G. cruentata in the Northeastern Brazilian coast. Habitat loss in conjunction with long-term overfishing can have irreversible consequences, which can impact not only the populations of commercially exploited crabs, but the dynamics of virtually the entire mangrove ecosystem. Rev. Biol. Trop. 63 (2): 443-457. Epub 2015 June 01.

The Relationship between Population Density and Body Size of the Giant Mountain Crab Indochinamon bhumibol (Naiyanetr, 2001), an Endangered Species of Freshwater Crab from Northeastern Thailand (Potamoidea: Potamidae)

“…Crab density was estimated in each sampling site as the number of individuals that were captured per area (total sampling plots) [19]. The sex ratio of the adult stage was estimated each month as the quotient of the number of males and the total number of individuals in the sample [20].…”

“…Diversity 2022, 14, x FOR PEER REVIEW 3 of 18 The abundance of I. bhumibol was compared between the two study sites (PL and PR) using a normalization and an independent sample t-test. One-way ANOVA was used to compare (1) body size parameters (carapace width, carapace length and weight) of all crabs and of both sexes between the 12 sampling sites and (2) population size and population density between the 12 sampling sites and seasons at the p = 0.05 level [20]. The relationship between population density and body size was investigated by correlation and linear regression analysis.…”

Ficha de Goniopsis cruentata

“…Um ponto importante é que as populações do Brasil compartilham fluxo gênico e, portanto, são passíveis de repovoamento (Buranelli & Mantelatto, 2019). No entanto, resultados obtidos por Hirose et al (2015), indicam que a alta intensidade da pesca pode estar afetando alguns parâmetros populacionais, reforçando a necessidade de desenvolver um plano de gestão e a criação de unidades de conservação por G. cruentata na costa nordeste do Brasil.…”

Population structure and fecundity of <i>Upogebia omissa</i> (Decapoda: Gebiidea: Upogebiidae) in an estuarine region in Sergipe, northeastern Brazil

“…The sampling program was conducted between July and November 2017, in a region called Croa do Goré (11°05'47''S -37°09'30''W), located approximately 5 km from the mouth of the Vaza-Barris estuary, one of the main estuarine system in Sergipe State, northeastern Brazil ( Figure 1A). This estuary extends for approximately 20 km along the coast and its mangrove forest is composed mainly by specimens of the genera Rizophora, Laguncularia and Avicennia (Carvalho & Fontes 2007;Hirose et al 2015). The burrows inhabited by mud shrimps were scattered along the substrate up to the intertidal zone, in a fringe mangrove forest ( Figure In each sampling, a transect of approximately 20 m was outlined parallel to the fringe mangrove forest.…”