It’s Dark Dark: Castleguard Cave Designated a Key Biodiversity Area
by Greg Horne
New signage in Castleguard Cave’s Subway Passage. Photo: Colin Magee
The Wildlife Conservation Society Canada (WCS) is implementing a plan to research, nominate, and assist with the designation of Key Biodiversity Areas (KBAs) across Canada. Their mission reads as follows:
Key Biodiversity Areas…are the most important places in the world for species and their habitats. Faced with a global environmental crisis we need to focus our collective efforts on conserving the places that matter most. The KBA Programme supports the identification, mapping, monitoring and conservation of KBAs to help safeguard the most critical sites for nature on our planet – from rainforests to reefs, mountains to marshes, deserts to grasslands and to the deepest parts of the oceans. KBA designation provides a means of highlighting the importance of an area, but does not provide any protections in and of itself. But highlighting these areas should spur federal and provincial and Indigenous governments and companies to take steps to protect the values that have led to their designation as KBAs. The KBA process is also an important tool for identifying areas with high ecological value that are vital for sustaining biodiversity. This can, for example, help us shift the focus of our protected areas planning in Canada away from areas with low or limited biodiversity to more productive and ecologically important areas that will contribute more to protecting biodiversity across larger landscapes[1].
Left: The Subway Passage of Castleguard Cave. Photo: Kathleen Graham
On January 30, 2023, a joint media release was made by Parks Canada and WCS after months of evaluation and discussion: “A tiny natural treasure had been found,” read the release, “buried deep beneath a mountain[2].” The story was picked up by CBC afternoon radio in Edmonton and Calgary, and a reporter asked me something like how dark the cave is. I explained the cave is about twenty-one kilometres long, light penetrates maybe 200 metres maximum, so most of the cave – like ninety-nine per cent of it – is dark dark.
The story was covered by the Royal Canadian Geographic Society[3]. Other online content was posted by BBC Canada, Gripped Magazine, and CTV Calgary. Earlier in December, the WCS showed a short video at the 2022 UN Biodiversity Conference, COP15, in Montréal.
The only Canadian cave nomination for KBA status so far has been Castleguard, the longest in Canada. At least one other cave in British Columbia was considered but rejected because of the risk that the nomination/designation of that cave, without any management protection, might lead to new or increased impacts to its resources. In the case of Castleguard Cave, it is situated in Banff National Park, and secured by a locked gate. The designation is not believed to change visitation impacts.
Above: Searching for invertebrates. Photo: Colin Magee
WCS states that “[S]ites can be designated under one of five criteria: threatened biodiversity; geographically restricted biodiversity; ecological integrity; biological processes; and irreplaceability.” The primary trigger species for the KBA is Stygobromus canadensis, a cave obligate aquatic amphipod only found so far in three locales in the cave. Discovered in 1977 during a major McMaster University expedition lead by Derek Ford, this species of invertebrate, and a much more widely distributed (in Castleguard Cave) aquatic isopod Salmasellus steganothrix, were collected for taxonomic identification. International amphipod expert John Holsinger (Virginia, USA) determined the amphipod was a unique new species, and to this day it has only been found in Castleguard Cave.
Below: Amphipod Stygobromus canadensis inside Castleguard Cave. Photo: Greg Horne
Initially, Stygobromus canadensis was found only in shallow pools near the end of the iconic Subway passage, about two kilometres from the entrance. More recently, in this twenty-first century, two additional sites in Castleguard for the species have been found, in a stream near Camp 1 and a still pool enroute to Boon’s Sump. The other secondary trigger species for the KBA, Salmasellus steganothrix, is found at a minimum of six sites in the cave: Ice Crawls (side wall inlet), The Pools, Boon’s Sump, Subway, near Camp 1, Second Fissure near F7 junction. Undoubtedly, with more dedicated searching, additional sites will be discovered.
Besides the two previous described species, two additional aquatic invertebrates have been found in the cave: a worm (Rhynchelmis saxosa), identified by S.V. Fend, collected by the author in Castleguard and Wood Buffalo caves), and a planarian flatworm species. As well, a tiny terrestrial mite (Robustocheles occulta) in the back of the cave.
Isopod Salmasellus soteganothrix inside Castleguard Cave. Photo: Greg Horne
Based on radioactive isotope dating of speleothems (formations like stalagmites), the current human traversable passages in the cave are a minimum of 700,000 years old. This is a very old landscape for Canada, most of Canada’s present landscape is ten or twenty thousand years old after being revealed from under melting continental glacial ice. Some of Castleguard’s invertebrate species were likely carrying on with their daily business of survival during the past continental-wide glaciation periods, the cave serving as a subglacial refugium for some species of preglacial fauna.
Very little is known about the life cycle of Stygobromus canadensis and Salmasellus steganothrix in the context of Castleguard. What exactly is their food source, how long do they live, what is their reproductive cycle? These and more questions are reasons to continue studying and monitoring them. The fact that a blind unpigmented critter, barely the size of a grain of rice, can capture our attention, even briefly, shows efforts to better understand caves and all the things they contain are worth it.
Greg Horne is a member of the Alberta Speleological Society. He has visited Castleguard Cave more than 20 times over the last 27 years. He is conducting research about the present flood hydrology and ice formation of the cave and its possible connection to climate change.
References
1 For more information about the Wildlife Conservation Society, see https://www.wcscanada.org/KBA.aspx
2 See https://www.wcscanada.org/Latest-News/ID/18625/A-tiny-natural-treasure-buried-deep-beneath-a-mountain.aspx. Note: The labelled invertebrate photo is incorrect, it shows another Castleguard species, Salmasellus steganothrix.
3 https://canadiangeographic.ca/articles/castleguard-cave-recognized-as-a-globally-significant-key-biodiversity-area/