The Subterranean Crustacean Fauna of Castleguard Cave, Columbia Icefields, Alberta, Canada, and its Zoogeographic Significance^∗

Abstract

A biological survey of Castleguard Cave has shown that the inner cave is inhabited by two species of aquatic crustaceans, the asellid isopod Salmasellus steganothrix and the crangonyctid amphipod Stygobromus canadensis, both of which are blind and unpigmented. The isopod is abundant throughout the portions of the system containing sediment-rich pools and was found in areas of the cave which lie beneath the Columbia Icefields. The amphipod, which is unique to Castleguard Cave, was found only in one series of pools about 2 km from the entrance.

The occurrence of these aquatic species so far inside an area fully glacierized during the Wisconsinan and even at present partially under a permanent icefield suggests that they may be remnants of very old preglacial distributions. Since it is known that the cave has remained intact and internally ice free for more than 720,000 yr, it is hypothesized that it has served as a subglacial refugium for these organisms.