Distribution patterns of the crab Ucides cordatus (Brachyura, Ucididae) at different spatial scales in subtropical mangroves of Paranaguá Bay (southern Brazil)

Abstract

Heterogeneity in the distribution of organisms occurs at a range of spatial scales, which may vary from few centimeters to hundreds of kilometers. The exclusion of small-scale variability from routine sampling designs may confound comparisons at larger scales and lead to inconsistent interpretation of data. Despite its ecological and social-economic importance, little is known about the spatial structure of the mangrove crab Ucides cordatus in the southwest Atlantic. Previous studies have commonly compared densities at relatively broad scales, relying on alleged distribution patterns (e.g., mangroves of distinct composition and structure). We have assessed variability patterns of U. cordatus in mangroves of Paranaguá Bay at four levels of spatial hierarchy (10 s km, km, 10 s m and m) using a nested ANOVA and variance components measures. The potential role of sediment parameters, pneumatophore density, and organic matter content in regulating observed patterns was assessed by multiple regression models. Densities of total and non-commercial size crabs varied mostly at 10 s m to km scales. Densities of commercial size crabs diVered at the scales of 10 s m and 10 s km. Variance components indicated that small-scale variation was the most important, contributing up to 70% of the crab density variability. Multiple regression models could not explain the observed variations. Processes driving diVerences in crab abundance were not related to the measured variables. Small-scale patchy distribution has direct implications to current management practices of U. cordatus. Future studies should consider processes operating at smaller scales, which are responsible for a complex mosaic of patches within previously described patterns.

Population status and fishery potential of the mangrove crab,Ucides cordatus(Linnaeus, 1763) in North-eastern Brazil

“…Macintosh, 1988;Warren, 1990;Skov et al, 2002;Salgado Kent & McGuinness, 2006), including U. cordatus (e.g. Alcantra-Filho, 1978;Alves & Nishida, 2003;Alves et al, 2005;Hattori, 2006;Schmidt et al, 2008a;Wunderlich et al, 2008, Piou et al, 2009Sandrini-Neto & Lana, 2011). Advantages of this methodology include: speed and consequent increase in sample size; conducting non-destructive sampling, which is important when work involves endangered species; and the possibility of obtaining measures of all individuals within sampling units (Schmidt et al, 2008a).…”

“…Considering that each burrow of U. cordatus is inhabited by a single crab (Costa, 1979;Alves et al, 2005), the number of burrows within the quadrats in each mangrove site was used to estimate the crab density (number of burrow m 22 ), and the diameter of the burrow entrance was used as a proxy crab size (e.g. Alcantara-Filho, 1978;Alves & Nishida, 2004;Alves et al, 2005;Hattori, 2006;Schmidt et al, 2008a;Wunderlich et al, 2008;Piou et al, 2009;Sandrini-Neto & Lana, 2011;Pinheiro & Almeida, 2015). The data of crab burrow size was classified in eight size classes of 10 mm, from 20-30 to 90-100 mm; and histograms of the class size-frequency distribution were produced.…”

“…Since 2000 a great number of studies have been executed, revealing aspects about the population status and ecology of this crab (e.g. Schories et al , 2003; Alves & Nishida 2004; Glaser & Diele, 2004; Diele et al , 2005; Pinheiro et al , 2005; Hattori, 2006; Nordhaus et al , 2006; Schmidt et al , 2008a, b; Wunderlich et al , 2008; Piou et al , 2009; Conti & Nalesso, 2010; Diele & Koch, 2010; Góes et al , 2010; Sandrini-Neto & Lana, 2011; Leite et al , 2012; Christofoletti et al , 2013; Amaral et al , 2014) and providing better conditions to develop an effective management strategy of this fishery resource (Diele et al , 2005; Duarte et al , 2014). The large size of Ucides cordatus suggests that this species has a high vulnerability to exploitation as it is generally correlated with slow growth, high age at maturity, long-lived (>10 years), low reproductive output and low natural mortality (Jennings et al , 1998; Pauly, 1998; Pinheiro et al , 2005; Diele & Koch, 2010).…”

Mangrove habitat partitioning by Ucides cordatus (Ucididae): effects of the degree of tidal flooding and tree-species composition during its life cycle

“…According to Icely and Jones (1978), Piou et al (2009), andSandrini-Neto andLana (2011), the spatial distribution and population structure of mangrove crabs can change as a function of one or more parameters, especially the species composition of the mangroves (Schories et al 2003;Koch et al 2005;Nordhaus and Wolff 2007), degree of flooding (Whitehouse et al 2001;Reinsel 2004), and texture and organic matter content of the sediment (Frusher et al 1994), leading to habitat partitioning (Caravello and Cameron 1987) and a possible change in the sex ratio. The sex ratio may also be influenced by different exploitation rates (Campbell 1992;Diele et al 2005), growth and mortality levels (Wenner 1972;Emmerson 1994;Johnson 2003), predation (Iribarne and Martinez 1999;Jaroensutasinee and Jaroensutasinee 2004), or salinity (Jury et al 1994).…”

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.

“…Nevertheless, considering that this study used the same field procedure for both mangroves, we can infer that the mean crab abundance found in the Vaza-Barris River 15 20 25 30 35 40 45 50 55 15 20 25 30 35 40 45 50 55 15 20 25 30 35 40 45 50 55 15 20 25 30 35 40 45 50 55 15 20 25 30 35 40 45 50 55 20 25 30 35 40 mangrove is lower than in the Sergipe River mangrove. These differences can be attributed to environmental factors that are intrinsic to a particular mangrove forest or crab population, such as primary productivity, pneumatophore density, or patterns of larval recruitment (Piou, Berger, & Feller, 2009;Sandrini-Neto, & Lana, 2012), but might also be a consequence of (Castiglioni, & Coelho, 2011). Therefore a large number of individuals of G. cruentata are usually required to produce a small amount of meat; according to Carriço et al (unpublished data), 120-150 adult crabs are needed to produce one kg of "catado".…”