Columbia Pebblesnail – State Wildlife Action Plan

Species is large with subglobular to trochoid shell having strong subsutural angulation or keel on body whorl; penis of medium size, sickle-shaped. In addition to body whorl shape, the frequently incomplete parietal lip, pigmented salivary glands, and position of seminal receptacle entirely lateral to albumen gland are unique to F. fuscus. This species is further distinguished by the relatively large size, channeled suture, and reddish-black color, not only of the periostracum but also of portions of the shell, excluding the aperture.

Overview

Species Common Name Columbia Pebblesnail
Species Scientific Name Fluminicola fuscus
Federal Listing Status Species of Concern

Ecoregions

Blue Mountains

Located in NE Oregon, the Blue Mountains ecoregion is the largest ecoregion in the state. It provides a diverse complex of mountain ranges, valleys, and plateaus that extend beyond Oregon into the states of Idaho and Washington.

Columbia Plateau

The Columbia Plateau ecoregion was shaped by cataclysmic floods and large deposits of wind-borne silt and sand earlier in its geological history. It is dominated by a rolling landscape of arid lowlands dissected by several important rivers, and extends from the eastern slopes of the Cascades Mountains, south and east from the Columbia River to the Blue Mountains.

East Cascades

The East Cascade ecoregion extends from the Cascade Mountains' summit east to the warmer, drier high desert and down the length of the state. This ecoregion varies dramatically from its cool, moist border with the West Cascades ecoregion to its dry eastern border, where it meets sagebrush desert landscapes.

Northern Basin and Range

The Northern Basin and Range ecoregion covers the very large southeastern portion of the state, from Burns south to the Nevada border and from the Christmas Valley east to Idaho. It is largely a high elevation desert-like area dominated by sagebrush communities and habitats.

West Cascades

The West Cascades ecoregion extends from east of the Cascade Mountains summit to the foothills of the Willamette, Umpqua, and Rogue Valleys, and spans the entire length of the state of Oregon. It is largely dominated by conifer forests, moving into alpine parklands and dwarf shrubs at higher elevations.

Willamette Valley

The Willamette Valley ecoregion is bounded on the west by the Coast Range and on the east by the Cascade Range. This long mostly level alluvial plain has some scattered areas of low basalt, and contrasts with productive farmland and large urban areas. It has the fastest-growing human population in the state resulting in challenges due to land-use changes.

Special needs

Columbia pebblesnails are found in small to large rivers, in swift current, on stable gravel to boulder substrate, and under rocks and vegetation. It is common at the edges of rapids or immediately downstream from whitewater areas, and becomes much less common or absent in major rapids. This species has narrow habitat tolerances and requires cold, unpolluted, fast-flowing, well oxygenated water in moderately large perennial streams with stable gravel to boulder substrate.

Limiting factors

Impaired water quality, habitat degradation and loss, and increasing fragmentation and isolation of the few remaining populations are the main threats to F. fuscus. Suitable habitat is threatened by impoundments, water diversions, increased siltation from grazing and agriculture (e.g., orchards), and increased industrial pollution (e.g., mining and pulp mill effluents). Competition from invasive snails may also threaten this species.

Data gaps

Collect life history information. Obtain current population size and trend data. Assess distribution and determine range. Evaluate population genetics.

Conservation actions

Monitor existing populations and survey suitable habitat for new populations. Protect remaining habitat. Manage sites to maintain water quantity and quality, native plant communities, and original streambed substrates

Key reference or plan

Blackburn, M., S. Foltz Jordan, and N. Duncan. 2020. Interagency Special Status/Sensitive Species Program (ISSSSP) Species Fact Sheet: Fluminicola fuscus. USDA Forest Service Region 6 and USDI Bureau of Land Management Oregon State Office. 27pp.