Hotwater physa (Physella wrighti) COSEWIC assessment and upate status report: chapter 8

Limiting Factors and Threats

The limiting factors for P. wrighti are its putative requirement for warm water and its need to access the water/air interface for respiration. The small population size and very limited geographic distribution make this species extremely vulnerable to disturbances due to anthropogenic activities.

An estimated 40,000 bathers use the hotsprings annually, and monitoring of the pools and stream is limited. Although soaps and shampoos are prohibited and signs ask bathers to shower before entering the hotsprings, the introduction of soaps, shampoos, sunblock or insect repellents is still possible. Large or cumulative quantities of such substances might accumulate and interfere with respiration or other life processes. As part of regular maintenance, Alpha Pool is cleaned weekly (A. Hansen, pers. comm., 2008). It seems likely that bathing and pool cleaning activities could crush or remove snails and eggs, since snails have been observed on the steps in lower Alpha Pool. Trampling may also be a threat, as some park visitors explore the margin of Alpha Stream.

The introduction of exotic animals or plants into the hotsprings could pose a threat to P. wrighti. Recently there have been two known introductions of turtles into the hotsprings (Hansen, pers. comm.; Elliott, pers. comm., cited in Heron 2007). These animals were found and removed. However, there is potential for highly devastating ecological effects from the introduction of a species that is an aggressive predator or competitor. For example, the extinction of the Banff longnose dace (Rhinichthys cataractae smithi) was the result of the introduction of a mosquito fish (Gambusia affinis) into Banff Hotsprings (COSEWIC 2006).

A change in the flow of water could threaten this species. Many years before the presence of P. wrighti was known, the natural flow of water from Alpha Pool to Alpha Stream was changed by the building of the dam.Routine maintenance and repair of the dam and weir are conducted to maintain the integrity of Alpha Pool and Stream, and maintains Hotwater Physa habitat. A catastrophic dam failure could cause a flood that could dislodge snails or disturb habitat. Decreased water flow, or diversion, during maintenance could also expose snails to drying, lethal air temperature, or alteredwater temperature as the hot and the cold water sources would not be pre-mixed.

Drilling associated with oil and gas exploration into the fracture zone where heated water from the recharge zone travels to the spring is identified as a potentially serious threat (Heron 2007). While not considered imminent because there is no exploration occurring in this area currently, northern B.C. is undergoing significant exploration, and the status of this threat could change in the future. The recharge zone is believed to be north of the springs, outside of the park boundary. Heated water enters through the subterranean fracture, although the exact pathway is unknown. The pathway is believed to reach an approximate maximum depth of 3.4 km below earth surface and maximum temperature of 120°C (Gilles Wendling, pers. comm.). Drilling into the fracture could redirect flows and dry out the springs.

Page details

Date modified: