40 
Charles R. Blem and Leann B. Blem 
had egg masses or larvae in them during the breeding season. However, 
two ponds with pH’s less than 4.5 produced larvae, and one of these, a 
large temporary pond in Chesterfield County, had more than 300 egg 
masses in it during each of the five breeding seasons from 1982 through 
1986. 
Mortality of controls was highly variable among egg masses in the 
laboratory, but in general was relatively low for water with such low pH 
values (Table 2; see Pough 1976, Pough and Wilson 1977). Control 
results for 1984 did not differ significantly (t = 1.6; p < 0.05) from those 
of 1985, and neither of these groups was different from spring-water 
tests (t = 1.3 and 0.4, respectively; p < 0.05). Mortality in control groups 
occurred during early embryonic stages, that is, stages 1 through 9 
(Rugh 1962). The only abnormalities noted were deformities of the 
posterior trunk of hatched larvae and there were relatively few of these 
(see Pough 1976). 
Very small amounts of sulfuric or nitric acid decreased the pH of 
test waters severely, indicating that water from these temporary ponds is 
poorly buffered. Furthermore, even small decreases in pH resulted in 
nearly total mortality of eggs/ larvae (Table 2). Mortality appeared to be 
caused mainly by severe shrinkage of the total egg mass, as described by 
Pough (1976). Shrinkage did not occur at pH levels of the natural ponds 
(Fig. 1). In fact, egg masses increased in size as expected in newly 
deposited eggs (Pough 1976). Acidity of pH less than 4.0 resulted in 
shrinkage of egg masses, in some cases to less than one-third of the 
original size (see Fig. 1). Shrinkage was roughly a function of pH, that 
is, the lower the pH, the greater the amount of shrinkage. The most 
severe cases resulted in egg masses less than one-fourth the expected 
size. 
Addition of aluminum sulfate to test aquaria resulted in higher 
mortality, and the mortality rate increased rapidly with very small 
increases in aluminum sulfate (Table 3). Slight increases of aluminum 
(0.05 ppm) did not significantly increase mortality as compared with 
pooled controls (t = 0.8), but 0. 10 and 0.23 ppm caused significant (p < 
0.05) increases in mortality (t = 2.1 and 3.8, respectively). 
DISCUSSION 
The observation that one low-pH pond apparently has supported a 
very large, successful population of spotted salamanders while few 
others have done so, suggests that this population is acid-tolerant or 
that the pond has one or more characteristics that reduce the deleterious 
effect of low pH. Our control tests indicate that tolerance of acidity was 
greater than that reported by Pough (1976) and was similar to that of an 
acid-tolerant population investigated by Cook (1983). Field observations, 
