Crescimento somático do caranguejo-uçá Ucides cordatus (Crustacea, Brachyura, Ocypodidae) em laboratório

Abstract

ABSTRACT. Somatic growth of the mangrove crab Ucides cordatus (Crustacea, Brachyura, Ocypodidae) in laboratory. In crustaceans, size increase occurs only immediately after molting when the animal is in the soft-shelled condition. The growth of Ucides cordatus (Linnaeus, 1763) was observed in laboratory, through its occurrence of molt, percentual increment of size and intermolt period. The study was realized from October/2000 to March/2002 and a total of 91 crabs (15 males, 33 females and 43 juveniles) were sampled in Itacuruçá -Coroa Grande mangrove, State of Rio de Janeiro, Brazil. The animals were maintained in two types of containers: adult crabs were kept in containers of 1000 l capacity, during eighteen months; while the juveniles were kept in plastic containers of 20 l capacity during eight months. The crabs were maintained in flowing seawater and fed on frozen leaves of Rhizophora mangle (L.) (Rhizophoraceae) and Laguncularia racemosa (Gaertn.) (Combretaceae), twice a week. The carapace width ranged from 50.1 to 70.0 mm in males, 40.2 to 80.0 mm to females and 1.1 to 40.1 mm to juveniles. The survival rate of the specimens studied was of 46.7% for males, 39.4% for females after eighteen months and 67.4% for juveniles after eight months. The males and females molted up to three times during the experiment, while the juveniles molted up twice. Molts occurred between August and April, showing more frequency during spring and summer. The increment of carapace width decreased with size, with mean was 2.21 ± 1.39% for males, 1.28 ± 0.84% for females and 2.89 ± 2.13% for juveniles. The relationship between the percentual increment and the carapace width can be expressed by the equation IM = -0.0707LC + 4.645 (r 2 = 0.40). The intermolt period was 191 ± 140 days for males, 216 ± 76.2 days for females and 54 ± 1.41 days for juveniles. The percentual increment of size was statistically significant (p<0,05) when compared males and females, and adults and juveniles.KEYWORDS. Somatic growth, crab, molting, increment, intermolt period.RESUMO. Em crustáceos, o aumento de tamanho ocorre imediatamente após a muda, quando o animal está com a carapaça mole. O crescimento de Ucides cordatus (Linnaeus, 1763) foi observado em laboratório, através da ocorrência de muda, incremento de muda e período de intermuda. O estudo foi realizado durante os meses de outubro/2000 a março/2002 e um total de 91 caranguejos (15 machos, 33 fêmeas e 43 juvenis) foi coletado no manguezal de Itacuruçá -Coroa Grande, Estado do Rio de Janeiro, Brasil. Os animais foram mantidos em dois tipos de tanques: os caranguejos adultos foram mantidos em tanques de 1000 l, durante 18 meses, enquanto os juvenis foram mantidos em tanques plásticos de 20 l de capacidade durante oito meses. Os animais foram mantidos em sistema aberto de circulação de água do mar e alimentados duas vezes por semana com folhas de Rhizophora mangle (L.) (Rhizophoraceae) e Laguncularia racemosa (Gaertn.) (Combretaceae). A largura da carapaça variou entre 50,1 a 70,0 mm nos machos, 40,2...

Does the upwelling phenomenon influence the population dynamics and management of the seabob shrimp Xiphopenaeus kroyeri (Heller, 1862) (Crustacea, Penaeidae)?

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