DALE, J. M., B. FREEDMAN, and J . KEREKES. 1985. Acidity and associated water chemistry of amphibian habitats in Nova Scotia. Can. J . Zool. 63: 97-105. One hundred and fifty-nine field sites consisting of ditches, bogs, marshes, ponds, and lakes in south and central Nova Scotia were surveyed for the presence of the adults, eggs, or larvae of I 1 amphibian species. Water samples were analyzed for pH, alkalinity, color, conductivity, Na, K, Mg, Ca, SO4, and CI. Discriminant function analysis revealed that none of these variables predicted a species' presence. Two three-species groups were found to be significantly associated among themselves, but mutually exclusive of each other. The two groups were ( i ) Amby.sroma mrrc-ulrrtum, Hyla curucifer, and Rnnrr sy1vatic.a and ( i i ) Rana c.lamitan.s, Rana c-aresbeiana, and Rona pa1u.stri.s. Runa sj~lvrrtic-rr and A . moc~ulorum were observed breeding successfully in an acidic bog (mean pH 4. I). R~n a c*lnmitan.s adults and larvae were located in the field at pHs as low as 3.5 and 3.9, respectively. Field transplant studies, using eggs of A . mcrc~ulrrtum and R . .sylvotic-a (at pH 5.7 and 4.1) and Bufo americ-anus (at pH 6.3 and 4. I), revealed that R . .sylvatic-a was least sensitive to acidity. There is considerable variation in acid tolerance among the various species of Nova Scotia amphibians. Nevertheless, successful breeding by some species is occurring at very low pHs. DALE, J . M., B. FREEDMAN et J. KEREKES. 1985. Acidity and associated water chemistry of amphibian habitats in Nova Scotia. Can. J . Zool. 63: 97-105. Cent cinquante-neuf sites du Sud et du centre de la ~ouvelle-~cosse, fossks. tourbii-res. markcages, ktangs et lacs, ont ktk Cchantillonnks dans le but de faire I'inventaire de onze especes d'amphibiens, adultes, oeufs ou larves. L'analyse des kchantillons d'eau recueillis en meme temps a permis de determiner le pH, I'alcalinite, la couleur, la conductivitk et les concentrations de Na, K, Mg, Ca. SO4 et CI. Une analyse discriminante a rkvklk qu'aucun de ces parametres ne permet de prkdire la presence d'une espece. Deux groupes d'especes associkes significativement entre elles s'excluent mutuellement. Ce sont, d'une part, Ambystoma mac~ulatum, Hyla c-rucifer, Rona sylvtrric.n, et, d'autre part, R . c*lamirnn.s, R . c~nte,sheicrncl et R . pcr1u.srri.s. Rana .sylvarica et A . mac~ulntum se sont reproduites avec succes dans une tourbiere (pH moyen = 4,l). Des adultes et des larves de R . c.1amiran.s ont ktk rencontrks a des pH tres bas, 3.5 et 3,9 respectivement. Des experiences de transfert en nature, notamment d'oeufs d'A. mac~ulatum et de R . sylvotir-a (a des pH de 5.7 et 4, I ) et de Bufo americnnu.~ (a des pH de 6,3 et 4, I ) ont rkvklk que R. .sylvcrric~a est I'espece la moins sensible a IIaciditk. I I existe une variation considerable de tolkrance a I'aciditk chez les diverses especes d'amphibiens de la Nouvelle-Ecosse. Nkanmoins, certaines especes rkussissent a se reproduire a des pH particulierement bas.[Traduit par le journal] in laboratory ...