Wetland Restoration and Invasive Species: Apple snail (Pomacea insularum) Feeding on Native and Invasive Aquatic Plants

Abstract

Abstract The apple snail Pomacea insularum is an aquatic invasive gastropod native to South America that has the potential to cause harm to aquatic ecosystems, wetland restoration, and agriculture. To predict the potential impact of this snail on aquatic ecosystems, we tested the feeding rate of P. insularum, under laboratory nonchoice experiments, for 3 species of invasive macrophytes and 13 species of native aquatic plants that are important for wetland restoration and health. High levels of consumption were recorded for four native species (Ceratophyllum demersum, Hymenocallis liriosme, Ruppia maritima, and Sagittaria lancifolia) and three invasive species (Colocasia esculenta, Alternanthera philoxeroides, and Eichhornia crassipes). In contrast, less than 10% of the biomass of Spartina alterniflora, Scirpus californicus, Thalia dealbata, and Typha latifolia was consumed by P. insularum over the test period. The palatability of macrophytes was negatively correlated with dry matter content, making our results generalizable to all regions where this invader may be present. Based on our results, wetland restoration in areas invaded by P. insularum should focus on emergent structural species with low palatability. Apple snails should not be considered as agents of biocontrol for invasive plants; although apple snails fed on invasive plants at a high rate, their consumption of many native species was even greater.