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Recovery Strategy and Action Plan for the Banff Springs Snail (Physella johnsoni) in Canada (Proposed)


Executive Summary

This document contains a Recovery Strategy and an Action Plan for the Banff Springs Snail (P. johnsoni).

The Banff Springs Snail is a globally rare snail with a highly specialized habitat and restricted distribution. It has been recorded from eleven thermal springs in BNP, was extirpated from six springs, and has now been re-established into two springs. Snail populations fluctuate seasonally by up to two orders of magnitude, making population trends difficult to ascertain. While the species does not appear to be in danger of extinction, some populations appear to be at greater risk of extirpation than others.

The Banff Springs Snail has a restricted distribution within each spring and outflow stream that is correlated with higher water temperatures, lower pH and dissolved oxygen, and higher hydrogen sulphide levels. Water flow and the presence of particular microbial species may be required by the snail, which grazes on microbial mats within the springs. It is most likely the dominant grazer in the thermal springs, contributes excrement nutrients, and likely provides a minor food source for some birds and snakes.

There are several threats to the Banff Springs Snail. Many thermal springs in BNP are highly modified and regulated, and are subject to impacts by visitors. The stoppage, redirection, and reduction of thermal water flows can have a significant impact on snail populations. Soaking and swimming, trampling, and limb-dipping (the dipping of feet or hands) have been recorded at all sites. Natural threats include a susceptibility to stochastic events (unpredictable large disturbances), large population fluctuations, and genetic inbreeding. A Research and Recovery Program has been in place within BNP since 1996, resulting in many improvements and reductions in threats.

The recovery of the Banff Springs Snail is considered technically and biologically feasible. The goal of the recovery strategy is to restore and maintain self-sustaining populations of the Banff Springs Snail within the species' historic range. The recovery objectives are to:

  • Protect populations and habitats by mitigating human and natural threats
  • Restore self-sustaining snail populations and habitat within historic range, where and when possible, and
  • Increase knowledge and understanding of snail ecology, thermal spring ecosystems and threats to them.

Specific actions, timelines, responsibilities, and performance measures are established in an Action Plan included in the document. Critical habitat has been identified for the Banff Springs Snail. A Strategic Environmental Assessment was completed and a summary is included.

The entire habitat of the Banff Springs Snail is found within BNP which is managed by the PCA under the CNPA. Four of the seven snail populations inhabit the highly regulated environment of the culturally significant C&BNHS. While recovery is administered by one jurisdiction, the juxtaposition of the snail's thermal spring habitat within BNP and the C&BNHS requires that recovery can only be achieved if both Ecological and Commemorative Integrity are fully integrated.