Sediment ingestion in the invasive apple snail Pomacea canaliculata

Abstract

Sediment represents both a habitat and a trophic resource for many aquatic organisms, commonly known as deposit feeders. One of the most important freshwater invaders around the world is the polyphagous and opportunistic apple snail Pomacea canaliculata, in which deposit feeding has not been reported. Our aims were to study the frequency of sediment ingestion at different seasons in four watercourses within its natural range and to evaluate, under laboratory conditions, the relevance of this trophic resource for growth and survival of hatchlings and juveniles. Sediment ingestion showed very high (80–100%) and similar frequencies in snails from different waterbodies and at different seasons. This trophic behaviour was also recorded in laboratory experiments which allowed hatchlings to survive longer and to grow faster and in the case of juveniles to maintain their live weights with a high level of activity. Sediment ingestion by P. canaliculata juveniles also reduces organic matter content in the sediment. Sediment ingestion represents an alternative feeding behaviour for this apple snail whose relevance increases when other trophic resources are absent or scarce. This may help young individuals to survive and populations to persist during food shortages, increasing the chances of invasion. The reduction by P. canaliculata of the organic matter content in the sediments could alter the biogeochemical processes occurring in them and enhances the role of this apple snail as an ecosystem engineer in aquatic environments.