Amphibian Physiology Research Articles

Effect of mercuric chloride on fertilization and larval development in the river frog, Rana heckscheri (Wright) (Anura: Ranidae)

Previous investigations have indicated that heavy metals such as copper, cadmium, lead and mercury can act as systemic toxicants in many species of wildlife. Although numerous studies have emphasized the effects of metals and pesticides on metabolism, growth, survivorship, neural processes and reproduction in a number of taxa, little information is available on the effects of sublethal concentrations of metals on the reproductive physiology of amphibians. Industrial processes and mining activities can release substantial concentrations of heavy metals such as mercury into aquatic habitats. Since most amphibians have obligate aquatic larval stages, they are exposed to pollutants discharged into the aquatic environment. Amphibians can act as accumulators of heavy metals and their larval stages are useful indicators of pollution levels in the field. What little data are available, indicate that metals can significantly reduce viability in amphibians through their actions on metabolism, development and gametogenesis. The recent concerns over worldwide declines in amphibian populations and the susceptibility of amphibian populations to environmental toxicants, led me to assess the effect of mercuric chloride, one of the most common and persistent toxicants in aquatic environments, on fertilization and larval development in the river frog, Rana heckscheri (Wright). Although there is some informationmore » on fish, very little data are available on the effects of mercury on fertilization in amphibians generally, and no published data exist for R. heckscheri. This species is a conspicuous component of the aquatic fauna of parts of the southeastern United States where mercury levels have increased significantly over the last two decades. 22 refs., 2 tabs.« less

Effects of environmental pH and temperature on embryonic survival capacity and metabolic rates in the smallmouth salamander, Ambystoma texanum.

Although the deleterious effects of acid precipitation on forest ecosystems and fisheries have been documented, relatively little information is available on the effects of environmental pH in combination with temperature on the survival capacity and/or physiology of amphibians. Increased acidity resulting from acid precipitation common to the northwestern United States, can lead to increased mortality in the spotted salamander, Ambystoma maculatum. In view of the potentially significant deleterious effects of stressful pH conditions on amphibian survivorship and the relative paucity of data on this subject, the present study was conducted in order to ascertain the combined effects of temperature and pH on embryonic metabolic rates and survival capacity in the smallmouth salamander, Ambystoma texanum Mathes. No previous data on these parameters are available for this species.