Ecological Role of the Banff Springs Snail

To better understand the ecological role of the Banff Springs Snail in thermal spring ecosystems, a simple model was constructed. The primary ecological role of the snail is as a grazer, where it eats the microbial community. The microbial community is composed of bacteria and algae that grow on the various substrates within the thermal spring pools and outflow streams. These substrates include sticks, rocks, leaves, other vegetation, and the concrete-lined pool edges. The snails also have been observed to eat material floating on the water’s surface. The snails may also inadvertently eat other, smaller microscopic animals in the springs. In turn, the snails process their food and their excretion is most likely used by other organisms, including the microbial community and community of other micro and macro-organisms in the springs.

A simple model of the ecological role of the Banff Springs Snail.

The snails can die a number of ways.

Birds most likely eat the snails. It has been shown by scientists that waterfowl, such as ducks, actively seek out snails, especially in the spring, to gain the calcium from the snail shells for their own egg production. The earliest returning robins are commonly observed near the thermal springs in Banff. Garter snakes, which have been observed to be active at the Cave and Basin even during the winter, could prey on Banff Spring Snails as could the introduced Mosquito Fish (
Gambusia affinis). However there appears to be little overlap between the snail and the Mosquito Fish as the fish require higher levels of dissolved oxygen, typically found where snail numbers are lower. Competition may be occurring between the snails and Soldier Fly larvae as both eat the microbial community. Typically, Soldier Fly larvae are at their maximum size in the spring, just as the microbial community begins to be affected by seasonal changes in the water chemistry of the springs and snail populations are declining.

Snails can also die from old age or when their habitat becomes altered naturally. A herd of elk walking through the thermal spring outflow stream can alter the stream’s course, stranding some snails but potentially creating new habitat for others.

One of the causes of snail death is also one of the easiest to control – the death of snails caused by humans through direct mortality or damage or destruction of the snail’s habitat or its food sources.

Next Page - What are the Threats to the Banff Springs Snail?