Molt and growth of an estuarine crab, Chasmagnathus granulatus (Brachyura: Varunidae), in Mar Chiquita coastal lagoon, Argentina

LUPPI TOMÁS; SPIVAK EDUARDO; BAS CLAUDIA; ANGER KLAUS

JOURNAL OF APPLIED ICHTHYOLOGY-ZEITSCHRIFT FUR ANGEWANDTE ICHTHYOLOGIE

Blackwell

Lugar: Berlin; Año: 2004 vol. 20 p. 333 - 344

0175-8659

Summary Juvenile and adult growth of Chasmagnathus granulatus was studied in the laboratory in terms of molt increment in size (MI) and the intermolt period (IP), comparing data obtained from short-term (STE) and long-term (LTE) laboratory experiments. Crabs in a pre-molt condition were collected for STE, including the entire size range of the species. Larger crabs remained in the laboratory no more than 14 days; the average time to molt was 5.8 ± 3.1 days. We registered the molt of 94 females, 64 males and 34 undifferentiated juveniles and calculated their MI. Moreover, 24 males and four females were reared in the laboratory over 3 years (LTE). Hiatt diagrams did not show sex-specific differences between juveniles of both sexes, but revealed differences between juveniles and adults in each sex as well as between adults of both sexes. The MI decreased gradually with size; this pattern was described with a quadratic model. The IP increased exponentially with size. The presence of regenerating limbs diminished the MI. The abdomen of females reached its final shape and maximum relative width at functional maturity. Growth curves for both sexes were calculated using the von Bertalanffy model, but this model yielded an underestimation of the actual maximum size of this crab.Chasmagnathus granulatus was studied in the laboratory in terms of molt increment in size (MI) and the intermolt period (IP), comparing data obtained from short-term (STE) and long-term (LTE) laboratory experiments. Crabs in a pre-molt condition were collected for STE, including the entire size range of the species. Larger crabs remained in the laboratory no more than 14 days; the average time to molt was 5.8 ± 3.1 days. We registered the molt of 94 females, 64 males and 34 undifferentiated juveniles and calculated their MI. Moreover, 24 males and four females were reared in the laboratory over 3 years (LTE). Hiatt diagrams did not show sex-specific differences between juveniles of both sexes, but revealed differences between juveniles and adults in each sex as well as between adults of both sexes. The MI decreased gradually with size; this pattern was described with a quadratic model. The IP increased exponentially with size. The presence of regenerating limbs diminished the MI. The abdomen of females reached its final shape and maximum relative width at functional maturity. Growth curves for both sexes were calculated using the von Bertalanffy model, but this model yielded an underestimation of the actual maximum size of this crab.