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In 2004 to 2006, in the Okanagan Valley, British Columbia, Canada, we measured pesticides, water chemistry, and hatching success of Great Basin spadefoot (Spea intermontana), Pacific treefrog (Pseudacris regilla), Western toad (Bufo boreas), and Columbia spotted frog (Rana luteiventris). Predator-proof cages containing Gosner Stage 4 eggs were placed in ponds in nonagricultural reference sites in conventionally sprayed and organic orchards. Seventeen pesticides were detected in ponds in sprayed orchards but occurred at low concentrations (ng/L) except for diazinon (1,410 ng/L). Chloride, sulfate, conductivity, nitrate, and phosphorus showed significant differences among sites. Spadefoot mean hatching success ranged from 0 to 92% among sprayed orchards, whereas the range was 48 to 98.6% among organic orchards and 51 to 95.5% among reference sites. Mean hatching success for Pacific treefrog was 22.1 to 76.1% among sprayed orchards, whereas the range was 83.4 to 97.1% among reference sites. Although sample sizes were small and replication was low, we found that trends in hatching success of eggs of Western toad and Columbia spotted frogs were consistent with the other species. Variables that correlated negatively with amphibian hatching success included 12 pesticides and seven water chemistry parameters. However, stepwise regression found that, in 2005, atrazine accounted for 79% of the variation in spadefoot hatching success and, in 2006, atrazine, total nitrate, and chlorpyrifos accounted for 80%. For Pacific treefrog there were no significant correlations with pesticide concentrations; rather, hatching success correlated with water chemistry parameters. The present study also emphasizes the variability in species sensitivity and importance of incorporating water chemistry into the interpretation of water quality for amphibians.

To determine temporal and geographic variations of environmentally persistent pollutants, the concentrations of several contaminants were measured in snapping turtle eggs in 1999 and 2000. Contaminants included polychlorinated biphenyls (PCBs), non- ortho PCBs, polychlorinated dibenzodioxins and furans, organochlorine pesticides, and total mercury. Egg collection sites within the St. Lawrence Area of Concern (AOC) and the Territory of Akwesasne included Turtle Creek, Snye Marsh, and Raquette River. Additional contaminated sites were Gray's Creek (within the St. Lawrence AOC boundary), Coote's Paradise (Hamilton Harbour AOC), and the Territory of Walpole Island (St. Clair AOC). Reference sites were Lake Sasajewun, Algonquin Provincial Park in central Ontario, and in close proximity to the St. Lawrence Area AOC, Hoasic Creek and Cooper Marsh. Eggs from clutches collected from Akwesasne contained the highest concentrations of contaminants. Mean total PCB concentrations for Akwesasne clutches ranged from 1,900 to 61,000 ng/g wet weight (w.w.), which was 360 to 3,100 times higher than the mean concentrations at the reference sites. The high levels of contaminants in eggs, from sites within Akwesasne, were consistent with trends reported in the past and reflect the influence of the proximity of heavy industry. Current contaminant concentrations in clutches from Coote's Paradise are comparable with those recorded in 1989 and 1990 but are 200 to 800 times lower than concentrations reported in 1984 and 1988. Eggs from Lake Sasajewun contained relatively low contaminant levels, which is consistent with atmospheric deposition. Our results support that snapping turtles are good indicators of temporal and geographic contaminant trends.

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