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Recovery Strategy for the Northern Riffleshell, Snuffbox, Round Pigtoe, Mudpuppy Mussel and Rayed Bean in Canada (Final)

8. Habitat – Snuffbox

Habitat Identification

The Snuffbox is typically found in riffle areas or shoals (runs) in small- to medium-sized rivers and streams (van der Schalie 1938, Dennis 1984). Its substrate preference has been described as anything from sandy to (Clarke 1981) to gravel, cobble and boulder (Buchanan 1980). It has been reported at depths of 0.5-2.5 m (Buchanan 1980; Baker 1928), and is found in areas with swift currents. Buchanan (1980) measured bottom velocities of 0.36-0.51 m/sec at collection sites in the Meramac River basin, Missouri. Many of the historical records for this species in Canada come from Lake Erie where it probably inhabited the wave-washed shoals. The Snuffbox is usually found entirely buried in the substrate (Buchanan 1980), or with only the posterior slope exposed to view (Ortmann 1919).

Habitats where the Snuffbox was found alive in the Sydenham River in 1998-1999 were consistent with those described above, i.e., shallow riffle/run areas with coarse substrates in a medium-sized river.

Currently Occupied Habitat

Methods for delineating currently occupied habitat for the Snuffbox follow the methods described for the Northern Riffleshell.

Geospatial Description

Currently occupied habitat for the Snuffbox can be defined as a 50 km reach of the East Sydenham River as well as two smaller portions of the Ausable River near Nairn and downstream in the vicinity of the Arkona Gorge (Figure 18).

Functional Description

Within the area defined under Currently Occupied Habitat only areas meeting the characteristics described below are deemed to represent habitat in need of conservation:

  • permanently wetted and
  • of a stream order greater than 2 (riverine population only) and
  • well-oxygenated riffles or runs (riverine populations only)
  • sand (< 2mm) or gravel (2 – 60mm) dominated substrate
  • steady to moderate flows (riverine populations only)
  • nearshore areas with firm sand or gravel substrate (Great Lakes populations).

Historically Occupied Habitat

The historically occupied habitat for the Snuffbox consists of the lower 60 km of the Thames River, the lower Grand River, Niagara River, Detroit River and the nearshore areas within Lake Erie and lake St. Clair (Figure 6).

Figure 18. Currently occupied habitat of the Snuffbox in the Sydenham and Ausable rivers.
Figure 18: Currently occupied habitat of the Snuffbox in the Sydenham and Ausable rivers.