Conservation Status of Freshwater Gastropods of Canada and the United States

Abstract

This is the first American Fisheries Society conservation assessment of freshwater gastropods (snails) from Canada and the United States by the Gastropod Subcommittee (Endangered Species Committee). This review covers 703 species representing 16 families and 93 genera, of which 67 species are considered extinct, or possibly extinct, 278 are endangered, 102 are threatened, 73 are vulnerable, 157 are currently stable, and 26 species have uncertain taxonomic status. Of the entire fauna, 74% of gastropods are imperiled (vulnerable, threatened, endangered) or extinct, which exceeds imperilment levels in fishes (39%) and crayfishes (48%) but is similar to that of mussels (72%). Comparison of modern to background extinction rates reveals that gastropods have the highest modern extinction rate yet observed, 9,539 times greater than background rates. Gastropods are highly susceptible to habitat loss and degradation, particularly narrow endemics restricted to a single spring or short stream reaches. Compilation of this review was hampered by a paucity of current distributional information and taxonomic uncertainties. Although research on several fronts including basic biology, physiology, conservation strategies, life history, and ecology are needed, systematics and curation of museum collections and databases coupled with comprehensive status surveys (geographic limits, threat identification) are priorities.

Genetic structuring in the Pyramid Elimia, Elimia potosiensis (Gastropoda, Pleuroceridae), with implications for pleurocerid conservation

“…Nearly 80% of all pleurocerids are imperiled (Johnson et al 2013), and most species designations still rely on shell morphology. The genetic species and population structure of most pleurocerid taxa remains unknown.…”

“…Only 22% of all freshwater snail species are stable in a conservation context, and recent extinctions support these rankings (Sada and Vinyard 2002, Hershler et al 2007, Johnson et al 2013. Thirty-three pleurocerid species are extinct, and of all federally endangered and threatened species, 55% of the listed snails are freshwater species including eight pleurocerids (Johnson et al 2013). Only six recognized species occur west of the Mississippi River (NatureServe 2017), with three of them occurring in the Interior Highlands.…”

“…As a result of the geological processes that formed it, the Interior Highlands has a distinct fauna with high instances of endemism and drainage patterns that have dictated diversity (Mayden 1985, Mayden 1988, Matthews and Robison 1998, Austin et al 2004, Bonett and Chippindale 2004. The Interior Highlands also served as a refugium for many species during pe-With nearly 170 recognized species (Johnson et al 2013), the family Pleuroceridae is the second largest group of freshwater snails in North America behind only the Hydrobiidae. As part of the 700 snail species in North America, pleurocerids are increasingly imperiled by river regulation, habitat loss, poor water quality, reduced water quantity, and invasive species (Johnson et al 2013).…”

“…The Interior Highlands also served as a refugium for many species during pe-With nearly 170 recognized species (Johnson et al 2013), the family Pleuroceridae is the second largest group of freshwater snails in North America behind only the Hydrobiidae. As part of the 700 snail species in North America, pleurocerids are increasingly imperiled by river regulation, habitat loss, poor water quality, reduced water quantity, and invasive species (Johnson et al 2013). Only 22% of all freshwater snail species are stable in a conservation context, and recent extinctions support these rankings (Sada and Vinyard 2002, Hershler et al 2007, Johnson et al 2013.…”

“…As part of the 700 snail species in North America, pleurocerids are increasingly imperiled by river regulation, habitat loss, poor water quality, reduced water quantity, and invasive species (Johnson et al 2013). Only 22% of all freshwater snail species are stable in a conservation context, and recent extinctions support these rankings (Sada and Vinyard 2002, Hershler et al 2007, Johnson et al 2013. Thirty-three pleurocerid species are extinct, and of all federally endangered and threatened species, 55% of the listed snails are freshwater species including eight pleurocerids (Johnson et al 2013).…”