Banff Springs snail
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| Banff Springs snail | ||||||||||||||
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| Physella johnsoni (Clench, 1926) |
In April 1997, the Banff Springs snail, Physella johnsoni, a small air-breathing freshwater snail in the family Physidae, became the first living mollusc to be placed on Canada's national list of species at risk. It was classified as endangered by COSEWIC.
This species of aquatic pulmonate gastropod mollusc is very unusual because it is adapted to life in an environment which is too harsh for most animals to survive in. The snails live in thermal springs where the water is low in oxygen and has a lot of hydrogen sulfide. The largest snails are only about one centimetre long, and like all of the Physidae, the shells are sinistral or left-handed.
Historically the snail was found in nine thermal springs in Banff National Park; however, since the 1920s, it can be found in only five of these locations, and unfortunately most of these five locations are high visitor use areas. Destruction and disturbance of the snail's habitat continue to threaten its survival; human actions such as illegal swimming, vandalism, garbage and coins thrown into the springs, all seriously disturb the springs' delicate ecosystems.
Parks Canada is trying to protect the species through education, law enforcement, and scientific research. In 1996 Parks Canada started a research and recovery program for the snail in an effort to protect it. The goals of the program are to maintain self-sustaining populations of the snail, re-establish populations at all historic locations, and hopefully to downlist the species' status.
The snail population fluctuates seasonally. During times when the numbers are critically low, the snail is most vulnerable to human disturbances or natural disasters (like the spring temporarily drying up). While scientists don't know exactly why the population fluctuates so much, it is probably due to changes in water temperature and chemistry or changes to the bacteria and algae. It is estimated that the population varies between 1,500 and 15,000 snails. At its lowest points, the entire population of snails can fit in an ice cream cone, and at its highest, in a one litre milk carton.
Every four weeks researchers and volunteers count the snails and analyze the water chemistry. There is also a captive breeding program being performed, and if it is successful, the snails will be introduced back to the four additional springs where the species was historically present. Eggs are currently hatching in captivity; the time from laying to hatching is four to eight days.
The snails' diet consists of Periphyton.
