Carrion consumption and its importance in a freshwater trophic generalist: the invasive apple snail Pomacea canaliculata

Abstract

Trophic flexibility is a relevant trait in the potential for organisms to establish widely,maintain high abundances, and spread post-invasion. Pomacea canaliculata is an apple snail that feeds primarily on aquatic macrophytes, although it also consumes other trophic resources that likely play an important role in its persistence and contribute to its impacts in invaded wetlands. We studied the ingestion rates P. canaliculata on carrion and its subsequent effects on growth, and we performed field and laboratory experiments to study the mechanism of carrion detection. We observed P. canaliculata snails of all sizes feeding on carrion. The specific ingestion rates of carrion decreased with snail size and were twenty times lower than when feeding only on lettuce. The growth rates of snails feeding only on carrion were 15-30% higher than those of fasting snails and 30% of those snails feeding on lettuce or lettuce and carrion. We found no evidence of distant chemoreception of carrion. The importance of carrion for P. canaliculata is mostly as an alternative resource when its preferred food is absent, and not a complementary resource that could enhance growth. Nevertheless, the ability of P. canaliculata to profit from carrion may help to explain its potential to establish widely and to have impacts on aquatic vegetation.