Effects of polychlorinated biphenyl 126 on green frog (Rana clamitans) and leopard frog (Rana pipiens) hatching success, development, and metamorphosis

Abstract

Abstract-Although increasing evidence links planar chlorinated hydrocarbons, such as polychlorinated biphenyls (PCBs), to decreases in survival and reproduction of fish, mammals, and birds near Green Bay, Wisconsin, and the Great Lakes, USA, relatively little is known of their bioaccumulation or of their possible effects in amphibians. We exposed embryos and larvae of two ranid species commonly occurring in the Green Bay ecosystem, the green frog (Rana clamitans) and the leopard frog (Rana pipiens), to PCB 126, a model coplanar PCB compound. Nominal concentrations ranged from 0.005 to 50 g/L, and exposure lasted through metamorphosis. Tissue concentrations of PCB 126 in tadpoles that did not metamorphose by the end of the experiment ranged from 1.2 to 9,600 ng/g wet mass. No significant mortality of embryos occurred before hatching; however, survival of larvae was significantly reduced at the highest concentration for both species. Few deformities were observed, but the incidence of edema was significantly higher in tadpoles exposed to 50 g/L. Swimming speed and growth of tadpoles was also significantly reduced in this treatment. The percent of tadpoles that reached metamorphosis was significantly lower in green frogs at the highest concentration, and no leopard frogs survived past day 47 of the experiment in this treatment. At high concentrations, PCB 126 affected both ranid species; however, sublethal effects were not apparent for the parameters we measured at concentrations that occur in water in the Green Bay ecosystem.

Genetic and maternal effect influences on viability of common frog tadpoles under different environmental conditions

“…No amphibian studies on the effects of environmental stress on quantitative genetic parameters have yet been published, although the early aquatic developmental stages of amphibians are known to be extremely sensitive to various environmental stresses, such as ultraviolet-B radiation (Blaustein et al, 1998), chemical pollutants (Hecnar, 1995;Rosenshield et al, 1999;Bridges and Semlitsch, 2000) and acidification (Bö hmer and Rahman, 1990). In fact, the recent global decline of amphibian populations (Alford and Richards, 1999;Houlahan et al, 2000) is believed to be -at least in part -a reflection of worldwide increase in the levels of these stresses (Alford and Richards, 1999;Corn, 2000).…”

Exposures to Estradiol, Ethinylestradiol and Octylphenol Affect Survival and Growth ofRana pipiens and Rana sylvaticaTadpoles

“…Further, it has been suggested that juvenile fish and embryos might be more susceptible to toxic stress when they are exposed during "critical windows" in their development (Mantovani et al, 1999). There is also significant variability among amphibian species regarding their sensitivity to environmental contaminants (Pauli et al, 1999;Rosenshield et al, 1999); however, these differences vary according to the specific compound to which they are exposed (Berrill et al, 1998). It has also been suggested that differences in response to toxicant exposure between species and within populations of the same species are due to genetic variation (Bridges & Semlitsch, 2000.…”

Congener‐specific analysis of polychlorinated dibenzo‐p‐dioxins, dibenzofurans, and coplanar polychlorinated biphenyls in frogs and their habitats, Kitakyushu, Japan

“…In the case of coplanar PCBs, injecting up to 2.3 mg/kg of 3,3′,4,4′,5‐P5CB into leopard frogs did not induce the expected cytochrome P450‐associated monooxygenases [27]. However, exposure to 5 to 50 μg/L of 3,3′,4,4′,5‐P5CB through the skin and gills showed various effects [28]. From these results, amphibians seem to have a tolerance for dioxin‐like chemicals.…”