Somatic growth in juveniles of the estuarine crab Chasmagnathus granulata Dana 1851 (Brachyura, Grapsidae), under laboratory conditions

Abstract

Male and female juvenile crabs of the species Chasmagnathus granulata were collected in Samborombón Bay (Argentina), on October 1994 and February 1995; these dates correspond to the beginning and end of the reproductive period of the species, respectively. No differences in the initial size (measured as carapace width, CW) existed between both clutches. Each clutch of juveniles was observed during a 1-year period, recording the percentage of molted crabs, intermolt period and percentual increment of size after each molting. At the end of the observation period, males and females from the October clutch reached the size of sexual maturity, while crabs of the remaining clutch did not. This difference was due to the higher increment in size of the October crabs at the third and fourth molts, compared to the February ones. Such difference seems to be related to an increase in reproductive effort during the breeding season, once the sexual maturity was attained.

Secondary production of Chasmagnathus granulatus (Crustacea; Decapoda) in a Ramsar Site from Argentina

“…Once sexual maturity is achieved, C. granulatus showed differential somatic growth between sexes, the females growing less than the males, as also noted by Rodríguez (1998) andD'Incao et al, (1993). It should be remembered that brachyurans females reach smaller sizes than males, because of the energy investment in reproduction and oviposition, instead of in growth.…”

“…Studies carried out in the growth of C. granulatus in Lagoa dos Patos (Brazil) estimated longevity from 1.7 to 2.03 years for males and females, respectively (D´Incao et al, 1993). However, López and Rodríguez (1998) concluded that this species, studied in Samborombón Bay, needed a minimum of two and a maximum of three years to reach sexual maturity from the larval stages. Luppi et al, op.…”

“…This lack of crabs on the surface could be due to the low temperatures and frosts registered during The reproductive season of C. granulatus comprises spring and summer months (September to March and even extending to April). Each female can spawn up to three or four times during the reproductive period, and thus females can produce more than one cohort during the same reproductive period (López and Rodríguez, 1998). Nevertheless, it is necessary to highlight the presence of recruits during the whole period of study.…”

Population structure of the South American Estuarine crab, Chasmagnathus granulatus (Brachyura: Varunidae) near the southern limit of its geographical distribution: comparison with northern populations

“…Dense populations of these crabs are associated with mudflats and saltmarshes in estuaries, bays and coastal lagoons of varying salinity, temperature and tidal patterns (Spivak, 1997). The structure of C. granulatus populations, its life-history, reproduction, feeding and ecological role have been studied in numerous locations characterized by low or fluctuating salinity, such as Lagoa dos Patos, southern Brazil (D'Incao et al, 1992;Ruffino et al, 1994), Samborombo´n Bay, Argentina (Botto & Irigoyen, 1979;Lo´pez & Rodrı´guez, 1998), Mar Chiquita Lagoon, Argentina Spivak et al, 1994;Spivak et al, 1996;Iribarne et al, 1997;Luppi et al, 1997Luppi et al, , 2002aItuarte et al, 2004) and Bahı´a Blanca, Argentina (Cervellini et al, 2000). In Mar Chiquita Lagoon, the reproduction of C. granulatus takes place from October to March, with several egg clutches produced during each season.…”

Organochlorine pesticides (OCs) and polychlorinated biphenyls (PCBs) in sediments and crabs (Chasmagnathus granulata, Dana, 1851) from mangroves of Guanabara Bay, Rio de Janeiro State, Brazil

“…granulata is omnivorous and detritivorous, feeding from sediment (D'Incao et al, 1990) and are perfectly adapted to aquatic or terrestrial habitats. Breeding period take place from October to February in Argentina (López & Rodriguez, 1998), but in the studied area ovigerous females were seen during all the year. Giménez & Torres (2002), point out that the first zoeal stage hatches in estuarine waters.…”