Abundance and arboreal tendencies of slugs in forested wetlands of southwestern Nova Scotia, Canada

Résumé

Non-native slugs, such as Arion, are becoming a concern for land managers in Nova Scotia, Canada, particularly in forested wetlands. They appear to have a highly diverse diet and may pose a particular risk to native slug species and to rare or at-risk lichens. We provide novel information on the distribution, abundance, arboreal tendencies, and seasonality of slugs in forested wetlands across southwestern Nova Scotia. We collected a total of 402 slugs representing seven species including two native species, Pale Mantleslug (Pallifera dorsalis) and Meadow Slug (Deroceras laeve), and five non-native Arion taxa. The three most abundantly caught taxa were Northern Dusky Arion (Arion fuscus), D. laeve, and Western Dusky Slug (Arion subfuscus). Arion fuscus and D. laeve were collected on the forest floor and on lichen-bearing trees, while A. subfuscus was collected only on the ground. All three taxa showed differences in collectability between July and September and low arboreal tendencies. We highlight that further studies are needed to better understand the biology and ecology of this largely neglected invertebrate group that seems to be dominated by non-native Arion species in the study region. Such information is crucial for conservationists and forest managers untangling the question of how non-native slugs affect native slug taxa and other groups including at-risk lichens.