Activity, substrate selection, and effect of a simulated Amazon flood regime on the behaviour of the apple snail, Pomacea bridgesii

Abstract

This study investigated the behaviour of Pomacea bridgesii, describing the daily activity, substrate selection and the influence of the flood regime in the Amazon, the species’ native habitat. The present study described the daily activity and substrate selection, and evaluated the activity adaptations of the gastropods in a simulated flood-pulse regime. Gastropods were collected in Amazonas, Brazil, in June 2013. Assessments of the daily behaviour, substrate selection, and flood-pulse simulation were made in experimental water tanks. The snails were observed hourly for 48h, and their behaviour recorded on an ethogram. The snails were more active during the night, when up to 80% of them moved about. In general, during both day and night, the gastropods used the pebble substrate most often. Comparing the day periods, a significant proportion of the individuals that were using the pebbles moved to other substrates (t=5; d.f.=2; P=0.03). The interaction of the behaviour of P. bridgesii with the simulated flood-pulse regime showed a statistical difference between the dry period and the period of maximum water level. The water regime of the Amazon floodplain directly influenced the activity of P. bridgesii, with responses including self-burying and activity interruption, with the operculum closed to minimise water loss.