Uso do espaço por Hypselartemon contusulus (Férussac, 1827) (Gastropoda, Streptaxidae) da Trilha da Parnaioca, Ilha Grande, Rio de Janeiro, Brasil

• Autor(a) principal: Viana, Tiago Abreu
• Data de Publicação: 2011
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/5801
• topic: Mollusca; Land snails; Ecology; Displacement; Predation activity; Gastrópode - Grande, Ilha (RJ); Streptaxidae - Grande, Ilha (RJ); Mollusca; Gastrópodes terrestres; Ecologia; Deslocamento; Atividade de predação; CNPQ::CIENCIAS BIOLOGICAS::ECOLOGIA

Spatial behavior of individuals is a key component to understanding and clarify migration and dispersion potential of species. Many factors affect locomotory activity of land mollusks, like temperature, light, humidity, period of the year, shell size, sex, reproductive strategy, age, co-specific density and food quantity. The mark-recapture method is used to study displacement of land snails. Land snails lend themselves to this kind of study because of their small size, easy handling, easy capture and small displacement distances and, consequently, small home ranges. These organisms serve as model to study spatial ecology and dispersion. Studies on population, concerning spatial behavior and distribution, population density and home range are rare for land snails and even rariest in natural tropical areas. Our study object is Hypselartemon contusulus (Férussac, 1827), a carnivorous land snail, family Streptaxidae, very common in leaf litter, in plane parts of secondary forest in the Trail of the Parnaioca, Ilha Grande, Rio de Janeiro. The species is endemic to Rio de Janeiro state. His size is 7.2 mm height, in maximum, showing six to seven whorls. In this work, we studied the environment variables temperature, soil temperature, air humidity, luminosity, leaf litter depth, shell size, co-specific density and prey density, connecting these ecologic data to the displacement observed to H. contusulus. The research hypothesis is that these variables affect its displacement. The work was carried out in Ilha Grande, south of the state of Rio de Janeiro, in the Angra dos Reis municipality. The animals were captured and marked with an individual code painted in the shell with orthographic liquid corrector and nankeen ink. The displacement distances, in cm, were recorded measuring the distances between subsequent markers. The results indicate that the used method is effective to mark individually H. contusulus in intermediate-term studies (until nine months). We suggest the use of this mark method to studies about land threatened land snailst, like some species of the families Bulimulidae, Megalobulimidae, Streptaxidae and Strophocheilidae. Hypselartemon contusulus does not maintain a minimum distance from its neighbours. The species is active during all the day and all year, showing locomotory activity and predation. Animals were not found sheltered under rock or dead wood. Sites of activity in opposition of sites of resting were not observed. Beckianum beckianum (Pfeiffer, 1846) was the preferential prey. Population density varied from 0.57 to 1.2 individuals/m2 between sampling episodes. The species move, in media, 26.57 ± 17.07 cm/24h, in the Trail of the Parnaioca, Ilha Grande. Home range of H. contusulus is small and does not exceed 0.48 m2, in three days and 3.64 m2 in 79 days. Displacement varied during the year, but this variation is not affected by the ecological variables. This is a plastic behavior in H. contusulus and, probably, controlled by endogenous factors.