| pesticides are involved with population declines of amphibians in the california sierra nevadas. | several species of frogs and toads are in serious decline in the sierra nevada mountains of california. these species include the threatened red-legged frog ( rana aurora ), foothill yellow-legged frog ( r. boylii ), mountain yellow-legged frog ( r. muscosa ), cascades frog ( rana cascadae ), western toad ( bufo boreas ) and yosemite toad ( b. canorus ). for many of these species current distributions are down to 10% of historical ranges. several factors including introduced predators, habitat l ... | 2001 | 12805670 |
| pathophysiology in mountain yellow-legged frogs (rana muscosa) during a chytridiomycosis outbreak. | the disease chytridiomycosis is responsible for declines and extirpations of amphibians worldwide. chytridiomycosis is caused by a fungal pathogen (batrachochytrium dendrobatidis) that infects amphibian skin. although we have a basic understanding of the pathophysiology from laboratory experiments, many mechanistic details remain unresolved and it is unknown if disease development is similar in wild amphibian populations. to gain a better understanding of chytridiomycosis pathophysiology in wild ... | 2012 | 22558145 |
| pesticides in mountain yellow-legged frogs (rana muscosa) from the sierra nevada mountains of california, usa. | in 1997, pesticide concentrations were measured in mountain yellow-legged frogs (rana muscosa) from two areas in the sierra nevada mountains of california, usa. one area (sixty lakes basin, kings canyon national park) had large, apparently healthy populations of frogs. a second area (tablelands, sequoia national park) once had large populations, but the species had been extirpated from this area by the early 1980s. the tablelands is exposed directly to prevailing winds from agricultural regions ... | 2004 | 15378994 |
| introduced trout sever trophic connections in watersheds: consequences for a declining amphibian. | trophic linkages between terrestrial and aquatic ecosystems are increasingly recognized as important yet poorly known features of food webs. here we describe research to understand the dynamics of lake food webs in relation to a native riparian amphibian and its interaction with introduced trout. the mountain yellow-legged frog rana muscosa is endemic to alpine watersheds of the sierra nevada mountains and the transverse ranges of california, but it has declined to a small fraction of its histor ... | 2007 | 17918397 |
| large-scale recovery of an endangered amphibian despite ongoing exposure to multiple stressors. | amphibians are one of the most threatened animal groups, with 32% of species at risk for extinction. given this imperiled status, is the disappearance of a large fraction of the earth's amphibians inevitable, or are some declining species more resilient than is generally assumed? we address this question in a species that is emblematic of many declining amphibians, the endangered sierra nevada yellow-legged frog (rana sierrae). based on >7,000 frog surveys conducted across yosemite national park ... | 2016 | 27698128 |
| reversing introduced species effects: experimental removal of introduced fish leads to rapid recovery of a declining frog. | amphibian population declines and extinctions are occurring even in the world's least impacted areas. the introduction and spread of nonnative predators is one of many proposed causes of amphibian declines. correlational studies have shown a negative relationship between introduced fishes and declining amphibians, but little direct experimental evidence is available. this study experimentally manipulated the presence and absence of widely introduced salmonids rainbow trout (oncorhynchus mykiss) ... | 2004 | 15136741 |
| multiple stressors and amphibian declines: dual impacts of pesticides and fish on yellow-legged frogs. | more than 40% of earth's 5700+ amphibian species have undergone recent declines. despite the likely involvement of multiple factors in driving these declines, most studies continue to focus on single stressors. in california (usa), separate studies have implicated either introduced fish or pesticides as causal agents. to date, however, no study has simultaneously evaluated the respective roles of these two potential stressors nor attempted to assess their relative importance, information critica ... | 2007 | 17489262 |
| toxicity of two insecticides to california, usa, anurans and its relevance to declining amphibian populations. | contaminants have been associated with population declines of several amphibian species in california (usa). pesticides from the central valley of california are transported by winds into the sierra nevada mountains and precipitate into wet meadows where amphibians breed. the present study examined the chronic toxicity of two of the insecticides most commonly used in the central valley and found in the mountains, chlorpyrifos and endosulfan, to larval pacific treefrogs (pseudacris regilla) and f ... | 2009 | 19290680 |