Bolander’s quillwort (Isoetes bolanderi) COSEWIC assessment and status report: chapter 10

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Limiting Factors and Threats

There is little available information on Isoetes bolanderi survival requirements. It is clear, however, that water quality degradation, particularly increased nutrients, increased water temperature, and excessive competition from associated aquatic plants has caused dramatic losses in plant vitality and population size in other species of aquatic quillworts, both in Europe and North America (Voge 1997, Britton and Brunton 1989).

The cause of the apparent extirpation of the Carthew Lakes population is unknown, and no impacts are apparent at the site. This is best regarded as a stochastic event to which small populations are vulnerable. The single remaining population of Isoetes bolanderi in Canada is also vulnerable to extirpation by a single catastrophic event.

Physical impacts, likely from recreational use, on the Summit Lakes population are the greatest immediate threat to Isoetes bolanderi in Canada. The lakeside location of the main recreational trail at Summit Lake may result in bank erosion, which has occurred along Summit Lake, leading to localized degradation of the shore and adjacent shallow-water sites (Brunton 1994). Some evidence of recreational wading was also evident. These impacts are highly localized and insignificant at present but could become significant were they to increase through greater recreational activity.

Another possibility is impacts from using Summit Lake as a water source for fire management. Fire pump or helicopter bucketing operations could physically disturb the plants and a fuel spill could affect the entire population of this small lake. Parks Canada has taken measures to minimize these disturbances.

Collection of plants by professional and amateur botanists is the only conceivable intentional human consumption of Isoetes bolanderi in Canada. This has occurred at an insignificant scale to date and is regulated by the Parks Canada research/collecting permit process. Isoetes are not cultivated for any but research purposes (Wherry 1972, Lellinger 1985) and are not recognized as having medicinal or herbal value (Erichsen-Brown 1979).

The most severe potential threat to the long-term viability of the Summit Lake population would be introduction of a toxic material (e.g. petrochemical, herbicide, fertilizer) which would either affect the population directly or encourage growth of competing aquatic species. One such event could extirpate this species from Canada.