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3114790 
Journal Article 
Altered pH and reduced calcium levels drive near extirpation of native crayfish, Cambarus bartonii, in Algonquin Park, Ontario, Canada 
Hadley, KR; Paterson, AM; Reid, RA; Rusak, JA; Somers, KM; Ingram, R; Smol, JP 
2015 
Yes 
Freshwater Science
ISSN: 2161-9549
EISSN: 2161-9565 
34 
3 
918-932 
English 
WOS:000359667700009 
Multiple 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 multiple proxy approach (i.e., diatoms and cladocerans) to reconstruct key environmental variables (e.g., pH) and long-term changes in lake chemistry (e.g., [Ca]) as they pertain to crayfish population loss. We found that interactions between pH and [Ca] have led to the decline in crayfish abundance and to the continued lack of recovery of these populations. Furthermore, lake-water [Ca] in all 4 Algonquin Park lakes are now <2.0 mg/L, the lowest hypothesized requirement for freshwater crayfish (2–10 mg/L), suggesting that short-term recovery of crayfish populations is unlikely, despite pH recovery. 
acidification; Algonquin Park; calcium decline; Cambarus bartonii; diatoms; multiple stressors; paleolimnology; zooplankton 
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• ISA NOxSOxPM Ecology (2020- Final Project Page)
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          Appendix 8