Hotwater physa (Physella wrighti) COSEWIC assessment and upate status report: chapter 1

Assessment Summary

Assessment Summary – April 2008

Common name: Hotwater Physa

Scientific name: Physella Wrighti

Status: Endangered

Reason for designation: This small snail is an endemic species living only within the hotsprings complex located in Liard River Hotsprings Provincial Park in British Columbia. The population is small, numbering fewer than 10,000 individuals and occupies an extremely restricted habitat around the margins of two pools and an outlet stream. Population size is believed to fluctuate by at least an order of magnitude in this short-lived snail (~1 year lifespan). The species is a habitat specialist requiring geothermally regulated water and substrates near the water/air interface in areas of no current. The hotsprings complex has been in use by humans for over 200 years. The species has survived structural modification and maintenance of the pools, the introduction of foreign substances such as soaps and shampoos, and trampling. However, a single event such as abrupt changes in water flow, chemical contamination or introduction of exotic species, could significantly affect persistence of this snail.

Occurrence: British Columbia

Status history: Designated Endangered in April 1998. Status re-examined and confirmed in May 2000 and April 2008. Last assessment based on an update status report.

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