Cryptic invasion of Northern Leopard Frogs (Rana pipiens) across phylogeographic boundaries and a dilemma for conservation of a declining amphibian

Abstract High levels of contamination in the aquatic environment and wildlife within the Ontario portion of the St. Lawrence River at the Cornwall Area of Concern (AOC) have raised questions about potential impacts on wildlife health. Northern leopard frog embryos were raised in two wetland sites within the AOC and at two reference sites to assess differences in water and sediment quality on survivorship and deformity rates. Chlorinated hydrocarbons (total polychlorinated biphenyls, organochlorine pesticides), polycyclic aromatic hydrocarbons, nutrients and heavy metals were measured in sediment and/or water from the study sites. Levels of some metals such as aluminium, cadmium, chromium and copper, exceeded federal and provincial guidelines for the protection of aquatic life, especially in the two AOC wetlands. Early stage tadpole survivorship was significantly lower and deformity frequency significantly higher at wetlands within the AOC; however, differences were likely not biologically significant. Survivorship and deformity rates of leopard frogs (Rana pipiens) at metamorphosis did not differ significantly among sites. Onset of metamorphosis was accelerated in tadpoles raised in wetlands within the AOC. Tadpoles raised in wetlands within the St. Lawrence River AOC took significantly less time to complete metamorphosis (53–55 days) than did tadpoles raised at reference sites (61–64 days). The phenology of metamorphosis was also more synchronous in tadpoles raised in the AOC, with all tadpoles reaching metamorphosis within a space of 3 to 7 days, as compared to 9 to 12 days at reference wetlands; these differences could not be accounted for by water temperature. Differences in development and survivorship rates between AOC and reference sites may be related to contaminant concentrations in water and sediment. However, no strong evidence for beneficial use impairment in terms of reproductive impairments or elevated deformity rates were seen from caged leopard frogs in the two AOC wetlands.

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Differences in size, pigmentation, and fluctuating asymmetry in stressed and nonstressed northern leopard frogs (Rana pipiens)

Ecoscience ◽

10.1080/11956860.2001.11682671 ◽

2001 ◽

Vol 8 (4) ◽

pp. 430-436 ◽

Cited By ~ 15

Author(s):

Natacha Gallant ◽

Kevin Teather

Keyword(s):

Fluctuating Asymmetry ◽

Rana Pipiens ◽

Leopard Frogs ◽

Northern Leopard Frogs

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Nematode parasites and leukocyte profiles of Northern Leopard Frogs, Rana pipiens: location, location, location

Canadian Journal of Zoology ◽

10.1139/cjz-2014-0156 ◽

2015 ◽

Vol 93 (1) ◽

pp. 41-49 ◽

Cited By ~ 1

Author(s):

Dave Shutler ◽

Andrée D. Gendron ◽

Myriam Rondeau ◽

David J. Marcogliese

Keyword(s):

Spatial Organization ◽

Rana Pipiens ◽

Pesticide Exposure ◽

Nematode Species ◽

Agricultural Pesticides ◽

Leopard Frogs ◽

Nematode Parasites ◽

Northern Leopard Frogs ◽

Host Parasite ◽

Leukocyte Profiles

Globally, amphibians face a variety of anthropogenic stresses that include exposure to contaminants such as agricultural pesticides. Pesticides may negatively affect amphibian immune systems, concomitantly increasing susceptibility to parasitism. We quantified nematodes and evaluated leukocyte profiles of Northern Leopard Frogs (Rana pipiens Schreber, 1782) collected from five wetlands in southwestern Quebec, Canada, that spanned a gradient of pesticide exposure. Three taxa of nematode parasites (Rhabdias ranae Walton, 1929, genus Oswaldocruzia Travassos, 1917, and genus Strongyloides Grassi, 1879) were sufficiently numerous for detailed evaluation. When all frogs were pooled, frog size was negatively correlated with nematode species richness, abundances of each of the three nematode species, and densities of three different leukocytes. When all frogs were pooled, there was strong evidence of both negative and positive associations between pairs of parasite species. However, none of the previous relationships was significant within wetlands. Our results reveal strong spatial organization of amphibian–parasite communities and illustrate the importance of controlling for sampling locale in evaluating host–parasite associations. Finally, although several response variables varied significantly among wetlands, causes of this variation did not appear to be related to variation in nematode parasitism or pesticide exposure.

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Photoinduced toxicity of fluoranthene to northern leopard frogs(Rana pipiens)

Environmental Toxicology and Chemistry ◽

10.1002/etc.5620180230 ◽

1999 ◽

Vol 18 (2) ◽

pp. 308-312 ◽

Cited By ~ 35

Author(s):

Philip D. Monson ◽

Daniel J. Call ◽

Dean A. Cox ◽

Karsten Liber ◽

Gerald T. Ankley

Keyword(s):

Rana Pipiens ◽

Leopard Frogs ◽

Photoinduced Toxicity ◽

Northern Leopard Frogs

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Influence of Ribeiroia ondatrae (Trematoda: Digenea) infection on limb development and survival of northern leopard frogs (Rana pipiens): effects of host stage and parasite-exposure level

Canadian Journal of Zoology ◽

10.1139/z03-099 ◽

2003 ◽

Vol 81 (7) ◽

pp. 1144-1153 ◽

Cited By ~ 51

Author(s):

Anna M Schotthoefer ◽

Anson V Koehler ◽

Carol U Meteyer ◽

Rebecca A Cole

Keyword(s):

Limb Development ◽

Rana Pipiens ◽

Significant Proportion ◽

Stage Structure ◽

Limb Bud ◽

Exposure Level ◽

Leopard Frogs ◽

In The Wild ◽

Limb Malformations ◽

Northern Leopard Frogs

Recent evidence suggests that infection by larvae of the trematode Ribeiroia ondatrae accounts for a significant proportion of limb malformations currently observed in amphibian populations of North America. However, the effects of R. ondatrae infection on northern leopard frogs (Rana pipiens), one of the species most frequently reported with malformations, have not been adequately explored. Moreover, the risk factors associated with R. ondatrae-induced malformations have not been clearly identified. We examined the effects of timing of infection on tadpole survival and limb development. Rana pipiens tadpoles were individually exposed to R. ondatrae cercariae at the pre-limb-bud (Gosner stages 24 and 25), limb-bud (Gosner stages 27 and 28), or paddle (Gosner stages 3133) stages of development and monitored through metamorphosis. The effects of infection were stage-specific. Infections acquired at the pre-limb-bud stage resulted in a high mortality rate (47.597.5%), whereas tadpoles infected at the limb-bud stage displayed a high malformation rate (16% overall), and the magnitude of effects increased with the level of exposure to cercariae. In contrast, infections acquired at the paddle stage had no effect on limb development or tadpole survival, which suggests that the timing of R. ondatrae infection in relation to the stage structure of tadpole populations in the wild is an important determinant of the degree to which populations are affected by R. ondatrae.

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