Altered pH and reduced calcium levels drive near extirpation of native crayfish, Cambarus bartonii, in Algonquin Park, Ontario, Canada

AbstractMultiple natural and anthropogenic stressors pose a serious threat to the health and diversity of biological communities. A growing body of research suggests that one consequence of these stressors has been a regional-scale loss of crayfish populations across south-central Ontario. The mechanisms contributing to the imperilment of crayfish probably include historical acidification and metal contamination, shoreline development and habitat loss, increased water temperature, declining [Ca] in lake water, and invasion by nonnative species (i.e., Smallmouth Bass and the rusty crayfish). Long-term monitoring data of crayfish populations in Algonquin Provincial Park (Ontario) have documented marked declines in Cambarus bartonii abundance despite the relatively isolated nature of the study lakes. Furthermore, monitoring data indicate that the onset of this decline may predate the monitoring record, thereby creating a need for the use of paleolimnological techniques to infer past conditions. We used a mul...