Ciclo reprodutivo do caranguejo violinista Uca rapax (Smith) (Crustacea, Brachyura, Ocypodidae) habitante de um estuário degradado em Paraty, Rio de Janeiro, Brasil
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Data
2006-06-01
Autores
Castiglioni, Daniela da S.
Negreiros-Fransozo, Maria L. [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Brasileira de Zoologia
Resumo
Este trabalho descreve o ciclo reprodutivo de Uca rapax (Smith, 1870) baseado em observações do seu desenvolvimento gonadal e ciclo de muda em uma área de manguezal degradado em Paraty, Estado do Rio de Janeiro. Os caranguejos foram capturados por duas pessoas mensalmente (julho/2001 a junho/2002) durante 15 minutos por meio da técnica de esforço de captura em período de maré baixa. No laboratório, os caranguejos foram mensurados quanto à largura da carapaça (LC); sendo o sexo, a condição ovígera e o estágio gonadal anotados. Os estágios de desenvolvimento gonadal foram determinados por meio da observação macroscópica das gônadas e os estágios de muda através da observação do grau de enrijecimento do tegumento. Os caranguejos que apresentavam gônadas imaturas e rudimentares foram considerados imaturos enquanto os demais estágios gonadais, maduros. Obteve-se um total de 1558 espécimes, sendo 801 machos e 757 fêmeas (16 fêmeas ovígeras). As fêmeas ovígeras representaram apenas 3% da população, talvez pelo fato destas fêmeas permanecerem em suas tocas. Apesar de terem sido encontrados caranguejos com gônadas maduras ao longo de todo o ano, o período de maior atividade reprodutiva em U. rapax ocorre nos meses mais quentes do ano (primavera-verão). A freqüência de caranguejos em atividade de muda ao longo do período de estudo foi baixa (12,8%) em relação aos caranguejos em intermuda. Provavelmente, U. rapax permaneça entocada nesse período crítico, que é a troca do exoesqueleto. Apesar de U.rapax ocorrer em um manguezal completamente degradado, o seu ciclo reprodutivo não foi afetado, quando comparado com de áreas não degradadas estudadas anteriormente. Tal fato pode ser sustentado pela presença de caranguejos potencialmente maduros ao longo do ano todo na área de estudo.
This present work describes the reproductive cycle of Uca rapax (Smith, 1870) based on observations of their gonadal development and molt cycles in a degraded mangrove area in Paraty, State of Rio de Janeiro. Two collectors captured the crabs monthly (from July 2001 to June 2002) during 15 minutes by procedure of capture per unit effort in low tide periods. Crabs were sexed, measured (carapace width - CW; 0.01 mm precision) and females were checked for eggs. Crab' stages of gonad development of both sexes were determined by direct and macroscopic observation and molt stage was estimated by the hardness of the tegument. A total of 1,558 specimens were collected, being 801 males and 757 females (16 ovigerous females). Ovigerous females accounted only about 3% of the population, perhaps because females usually remain underground in closed burrows during the incubation, which can not be seen easily in the field. Crabs with mature gonads were found year-round, but most reproduction in U. rapax occurred during the warmer months of the year (spring-summer). The frequency of crabs in molt activity was lower (12.8%) than intermolt crabs. Probably, U. rapax burrowed in this critic period that is the change of exoskeleton, minimizing the risks imposed by the occurrence of a soft skeleton. Despite of U. rapax be occurring in a properly degraded mangrove, its reproductive cycle seems to be not affected by the habitat condition, when it is compared with areas of the mangroves no impacted by human action. This fact is supported by the presence of potentially mature crabs year-round at the study area.
This present work describes the reproductive cycle of Uca rapax (Smith, 1870) based on observations of their gonadal development and molt cycles in a degraded mangrove area in Paraty, State of Rio de Janeiro. Two collectors captured the crabs monthly (from July 2001 to June 2002) during 15 minutes by procedure of capture per unit effort in low tide periods. Crabs were sexed, measured (carapace width - CW; 0.01 mm precision) and females were checked for eggs. Crab' stages of gonad development of both sexes were determined by direct and macroscopic observation and molt stage was estimated by the hardness of the tegument. A total of 1,558 specimens were collected, being 801 males and 757 females (16 ovigerous females). Ovigerous females accounted only about 3% of the population, perhaps because females usually remain underground in closed burrows during the incubation, which can not be seen easily in the field. Crabs with mature gonads were found year-round, but most reproduction in U. rapax occurred during the warmer months of the year (spring-summer). The frequency of crabs in molt activity was lower (12.8%) than intermolt crabs. Probably, U. rapax burrowed in this critic period that is the change of exoskeleton, minimizing the risks imposed by the occurrence of a soft skeleton. Despite of U. rapax be occurring in a properly degraded mangrove, its reproductive cycle seems to be not affected by the habitat condition, when it is compared with areas of the mangroves no impacted by human action. This fact is supported by the presence of potentially mature crabs year-round at the study area.
Descrição
Palavras-chave
Ciclo de muda, desenvolvimento gonadal, estuário, Estuary, gonadal development, molt cycle
Como citar
Revista Brasileira de Zoologia. Sociedade Brasileira de Zoologia, v. 23, n. 2, p. 331-339, 2006.