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Artigo publicado – Biologia populacional do Caranguejo-uçá


Durante os dois últimos anos de graduação, realizei pesquisa científica no Rio Joanes, Bahia, que rendeu essa publicação na Revista Nauplius.

Entitulado: Population biology of the ‘uçá’-crab, Ucides cordatus(Linnaeus, 1763)(Brachyura: Ucididae), in mangroves of the Joanes River, Bahia State,Brazil

Biologia populacional de Ucides cordatus (Linnaeus, 1763)(Brachyura: Ucididae), em manguezal do Rio Joanes, Bahia, Brasil.

Acessível também através deste link -> Article Moraes et al 2015 – Population Biology of the Uçá- crab


This study evaluated the population structure, relative growth and morphological maturity size in
Ucides cordatus in the Joanes River, Bahia State (Brazil).Crabs were sampled in a fragmented and human-altered mangrove ecosystem in a Brazilian Environmental Protected Area (EPA). A total of 431 crabs were sampled (265 males and166 females) between September 2011 and August 2012. The following measurements were taken using precision callipers: carapace width (CW) and length (CL), the lengthof the propodus of the major cheliped (PL, males only), and the width of the 5th somite of the abdomen (AW, females only). Specimens were also weighed to a precision of 0.5 g
on a scale to obtain the total wet weight (WW). The relative growth of this species was
studied by using biometric relationships to estimate the morphological maturity size in
both sexes (PLxCW in males and AWxCW in females). The overall sex ratio was 1.6:1, with
a predominance of males (p< 0.05). The population structure of ‘uçá’-crabs was composed
of two normal curves (juveniles and adults) in both sexes. A relative growth analysis using
the CLxCW relationship revealed a negative allometric growth in adult males whereas
adult females exhibited an isometric growth, with an inverse pattern occurring in juveniles.
In males, the PLxCW relationship indicated a change in allometric growth at 39.4 mm
CW (isometric growth in juveniles changing to positive allometry growth in adults). In
females, the AWxCW relationship indicates that morphological maturity occurs at a delay
(44.5 mm CW) and that growth changes between phases (positive allometry to isometry).
Isometric growth was found using the WWxCW relationship, also regardless of sex. A
literature review combined with results previously published about this species in northeast
Brazilian region suggests that U. cordatushad a seasonal reproduction during six months
(from December to May), with a fattening season in the following six months (June to
November). Joanes River is an environmental protected area, but had a high anthropic
pressure by closed condos and marinas. Despite the high anthropic pressure on this EPA,
the population structure and reproduction of U. cordatus did not appear to be affected.

Este trabalho avaliou a estrutura populacional, crescimento relativo e tamanho da maturidade morfológica em Ucides cordatus.

Para melhor visualização da espécie estudada neste estudo, veja a foto abaixo.


Palavras-chave: Biologia populacional; Ucides cordatus; manguezal impactado; crescimento relativo; APA Rio Joanes; Bahia; Brasil

Words-keys: population biology, mangrove land crab, impacted mangrove, growth relative, River Joanes.

Growth alometric – Crab (crescimento alométrico – caranguejo)

In decapods three types of allometry  exist:

(i) positive allometry or progressive geometric growth, in which the dependent variable grows fast with respect to body size, (ii) isometric or arithmetic growth, and (iii) negative allometry or retrogressive geometric growth, in which the dependent variable grows slower than body size. Chelipeds are the best example of crustacean allometric growth. In males of the crab Arenaeus caribrarius (Pinheiro and Fransozo 1993), crayfish Orconectes virilis, and blue clawed (BC) males of Macrobrachium rosenbergii (Kuris et al 1987), chela growth shows positive allometry (Aiken and Waddy 1992), while it is isometric in juveniles and females (Pinheiro and Fransozo,1993).

In heterochelous decapods chelipeds are further differentiated into major (crusher) and minor (cutter) based on morphologically and functionally different dentition paterns (Levinton et al 1995). The large and robust chela with molariform teeth, known as the crusher, can yield more force than the minor, which has many cutting teeth and spiniform setae (figure 1) (Mariappan and Balasundaram 1997). Major and minor chelae possess differential operating forces measured as ideal mechanical advantage 1979). In male Uca and Alpheus , the major chela is used for aggressive and courtship displays, while the other is used for capture and manipulation of prey and grooming (Hazlett 1962; Nolan and Salmon 1970; Crane 1975). Many crustaceans have spatulate chelae which are used to scrap algae from rocks (McLaughlin 1982). The atyishrimps use brush and spiny setae on chelipeds to scrap up debris (Fryer 1960). In Macrobrachium australe thminor chela endowed with abundant bristles serves as sort of net to catch prey while the major chela is used tpick up prey. Such a differential function among chelpeds is also observed in Homarus spp. (Davis 1987Chela size is also related to feeding habits. For instance detritivorous crabs have small slender claws (Seed an Hughes 1995) while carnivorous counterparts like Ocypode spp. possess enlarged chelae to facilitate predation In Macrobrachium nobilii, the robust second pair is use for prey capture and the slender first pair functions t deliver the food to the mouth (P Mariappan and Balasundaram, unpublished data).

fonte: J. Biosci.  |  vol. 25  |  No. 3  |  September 2000