44 
Charles R. Blem and Leann B. Blem 
composition, depending upon the local soil composition and the nature 
of the decomposing organic material in the water. For example, in our 
study area, soil maps indicate a mosaic of soils that vary in acidity and 
aluminum content (Hodges 1978). The local vegetation around breeding 
ponds may be pines, hardwood forest, or old field. The acidity of 
breeding pools may be increased by pine needles and/or oak leaves 
through humic acids produced because of poor rates of decomposition, 
but the products of other plants may not be so acidic (Smith 1986). The 
interactions between pH, organic matter, and aluminum may be complex, 
but in general it appears that high concentrations of organic compounds 
may decrease available aluminum ions by binding with them (Pott et al. 
1985). 
In summary, the results of the present study indicate that we should 
be cautious in attributing tolerance of acidity to populations of spotted 
salamanders breeding in ponds of low pH. Even so, it appears that A. 
maculatum in parts of Virginia has a dismal future because the slightest 
increases in acidity may cause its extirpation. 
ACKNOWLEDGMENTS . — We are indebted to the Department of 
Biology, Virginia Commonwealth University, and particularly Martha 
D. Berliner, for partial support of this study. We are grateful to Carolyn 
Conway for the loan of equipment, to Fred Hawkridge for valuable 
advice about water chemistry, and to Ralph Mendenhall for sharing 
measurements of soil aluminum with us. Mark Zimmerman and members 
of the 1984 physiological ecology class at Virginia Commonwealth 
University helped make some measurements. 
LITERATURE CITED 
Clark, K. L., and R. J. Hall. 1985. Effects of elevated hydrogen ion and 
aluminum concentrations on the survival of amphibian embryos and larvae. 
Can. J. Zool. 63:116-123. 
Cook, R. P. 1983. Effects of acid precipitation on embryonic mortality of 
Ambystoma salamanders in the Connecticut Valley of Massachusetts. Biol. 
Conser. 27:77-88. 
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. 
Dunson, W. A., and J. Connell. 1982. Specific inhibition of hatching in 
amphibian embryos by low pH. J. Herp. 16:314-316. 
Freda, J., and W. A. Dunson. 1984. Sodium balance of amphibian larvae 
exposed to low environmental pH. Physiol. Zool. 57:435-443. 
Freda, J., and W. A. Dunson. 1985. The influence of external cation 
concentration on the hatching of amphibian embryos in water of low pH. 
Can. J. Zool. 63:2649-2656. 
