Population dynamics of Megalobulimus paranaguensis (Gastropoda: Pulmonata) in the southeast coast of Brazil

Marcel S Miranda,José H Fontenelle

doi:10.1590/s1984-46702015000600005

Abstract

ABSTRACT. The population dynamics of Megalobulimus paranaguensis (Pilsbry & Ihering, 1900), a large and long-lived land gastropod from Brazil's Southeast (Atlantic Forest) was studied between 2006 and 2009, at an urban park in the city of Santos, state of Sao Paulo. The study included biometry, weighing, and marking and recapture of adult individuals. The variables obtained from specimens were correlated with the environmental variables of the study period. The survival rate of the adult snail population was 96.7%. Recruitment showed several peaks during the year, and was concentrated between April and August, except in 2009, when there was only one peak in August. Specimen abundance progressively increased from 2006 on, with a trend towards relative stability during that period. The condition factor remained relatively stable as well, decreasing from December to February. The potential evapotranspiration and precipitation influenced the number of captures, and the mean temperature influenced the condition factor. Megalobulimus paranaguensis goes through a period of dormancy in the tropical summer, which is between November and February, but remains active in the winter. The survival rate of M. paranaguensis was high, and may be the result of having its annual cycle synchronized with the tropical climate of the Atlantic forest.

Highlights

Megalobulimus Miller, 1878, which includes species popularly known as aruá-do-mato, is a group of Neotropical giant snails of Megalobuliminae
Only mean temperature, potential evapotranspiration and precipitation are shown, since they were the only variables that influenced the number of captures and condition factor (Figs. 6-8)
Our data show that the population of M. paranaguensis is highly resistant and has a high survival rate

Summary

Introduction

Megalobulimus Miller, 1878, which includes species popularly known as aruá-do-mato, is a group of Neotropical giant snails of Megalobuliminae. Megalobulimus spp. populations tend to occur in low densities (ESTON et al 2006) and, like other native species of terrestrial mollusks, they have low reproductive potential, spawning only two to five eggs per batch (SOBREIRA & MOLINA 2002). They are herbivorous, go through a dormancy period, and bury themselves in the rainforest soil or leaf litter during the day (BEQUAERT 1948). The aim of this study was to analyze the population dynamics of M. paranaguensis from Santos during four years (2006-2009)

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Conclusion