Monitoring the Small and Slimy - Protected Areas Should Be Monitoring Native and Non-native Slugs (Mollusca: Gastropoda)

Although slugs (Mollusca: Gastropoda) are known to be important generalist herbivores, fungivores, and detrivores in a variety of ecosystems, little is known about their abundance and diversity in protected areas. Likewise, the presence of non-native slug species and their impacts on invaded ecosystems have also not been well documented. In this study, the abundance and diversity of native and non-native slugs was investigated in a sensitive protected area comprised of a recently burned black spruce (Picea mariana) - lichen (Cladonia) woodland in Terra Nova National Park, Newfoundland, Canada. To estimate the diversity and abundance of slugs, pitfall traps were established in areas of high-burn intensity, including sites within and at the edge of the burn, low-burn intensity, and a non-burned reference. Of the nine slug taxa known from Newfoundland, five were captured within burned sites; of those five taxa, only one, Deroceras laeve, is native. Almost 90% of captures were of non-native taxa; dominant slug taxa were the introduced Anion subfuscus aggregate (agg.) and A. hortensis agg. The majority of captures occurred at the edge of the burn, and least in the high-intensity open sites. Given that non-native species can dominate the slug fauna in naturally disturbed areas, it is recommended that monitoring for these non-native invasive species and their impact on native vegetation be implemented within protected areas. The invasive nature of non-native slugs and their pivotal role in in uencing biodiversity and plant regeneration suggests that these invertebrates are key elements within a monitoring framework of protected areas.