Global amphibian declines: sorting the hypotheses

Collins, James P.; Storfer, and Andrew

doi:10.1046/j.1472-4642.2003.00012.x

Cited by 835 publications

(561 citation statements)

References 57 publications

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“…Despite the insular isolation of Sicily which can prevent the undesirable dispersal of the alien species in other geographic areas, insular communities and amphibian populations are considered particularly vulnerable to biological invasions (Collins and Storfer 2003;Savage 1987). So the effects of African clawed frog invasion reported in this study is cause for high concern.…”

Section: Discussionmentioning

confidence: 83%

Can the introduction of Xenopus laevis affect native amphibian populations? Reduction of reproductive occurrence in presence of the invasive species

2010

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Biological invasions are regarded as a form of global change and potential cause of biodiversity loss. Xenopus laevis is an anuran amphibian native to sub-Saharan Africa with strong invasive capacity, especially in geographic regions with a Mediterranean climate. In spite of the worldwide diffusion of X. laevis, the effective impact on local ecosystems and native amphibian populations is poorly quantified. A large population of X. laevis occurs in Sicily and our main aim of this work was to assess the consequences of introduction of this alien species on local amphibian populations. In this study we compare the occurrence of reproduction of native amphibians in ponds with and without X. laevis, and before and after the alien colonization. The results of our study shows that, when X. laevis establishes a conspicuous population in a pond system, the populations of Discoglossus pictus, Hyla intermedia and Pelophylax synklepton esculentus show clear signs of distress and the occurrence of reproduction of these native amphibians collapses. In contrast, the populations of Bufo bufo do not appear to be affected by the alien species. Since the Sicilian population of X. laevis shows a strong dispersal capacity, proportionate and quick interventions become necessary to bound the detriment to the Sicilian amphibians populations.

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Section: Discussionmentioning

confidence: 83%

Can the introduction of Xenopus laevis affect native amphibian populations? Reduction of reproductive occurrence in presence of the invasive species

2010

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“…Degradation and loss of habitat are among the primary reasons amphibian populations have declined worldwide (Collins and Storfer, 2003). Between 1850 and 1950 the amount of farmland in the United States increased from less than 300 million to more than 1.1 billion Science of the Total Environment 502 (2015) [80][81][82][83][84][85][86][87][88][89][90] acres (U.S. Department of Agriculture, 2013).…”

Section: Introductionmentioning

confidence: 99%

Pesticide concentrations in frog tissue and wetland habitats in a landscape dominated by agriculture

Smalling

Reeves

Muths

et al. 2015

Science of The Total Environment

127

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Habitat loss and exposure to pesticides are likely primary factors contributing to amphibian decline in agricultural landscapes. Conservation efforts have attempted to restore wetlands lost through landscape modifications to reduce contaminant loads in surface waters and providing quality habitat to wildlife. The benefits of this increased wetland area, perhaps especially for amphibians, may be negated if habitat quality is insufficient to support persistent populations. We examined the presence of pesticides and nutrients in water and sediment as indicators of habitat quality and assessed the bioaccumulation of pesticides in the tissue of twonative amphibian species Pseudacris maculata (chorus frogs) and Lithobates pipiens (leopard frogs) at six wetlands (3 restored and 3 reference) in Iowa, USA. Restored wetlands are positioned on the landscape to receive subsurface tile drainage water while referencewetlands receive water fromoverland run-off and shallow groundwater sources. Concentrations of the pesticides frequently detected inwater and sediment samples were not different between wetland types. The median concentration of atrazine in surface water was 0.2 μg/ L. Reproductive abnormalities in leopard frogs have been observed in other studies at these concentrations. Nutrient concentrations were higher in the restored wetlands but lower than concentrations thought lethal to frogs. Complex mixtures of pesticides including up to 8 fungicides, some previously unreported in tissue, were detected with concentrations ranging from 0.08 to 1500 μg/kg wet weight. No significant differences in pesticide concentrations were observed between species, although concentrations tended to be higher in leopard frogs compared to chorus frogs, possibly because of differences in life histories. Our results provide information on habitat quality in restored wetlands that will assist state and federal agencies, landowners, and resource managers in identifying and implementing conservation and management actions for these and similar wetlands in agriculturally dominated landscapes. RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. H I G H L I G H T S• Habitat quality was similar between restored and reference wetlands in Iowa.• Complex mixtures of pesticides are detected in frog tissues (liver and whole body).• The number of fungicides (up to 8) in frog tissues is largest reported to date.• Life history has the potential to impact pesticide bioaccumulation in frogs. Habitat loss and exposure to pesticides are likely primary factors contributing to amphibian decline in agricultural landscapes. Conservation efforts have attempted to restore wetlands lost through landscape modifications to reduce contaminant loads in surface waters and providing quality habitat to wildlife. The benefits of this increased wetland area, perhaps especially for amphibians, may be negated if habitat quality is insufficient t...

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“…Pondbreeding amphibians provide especially good study systems for examining the effects of aquatic breeding habitats on population parameters, because breeding ponds have quantifiable features and often demarcate discrete yearly cohorts of breeding populations. Additionally, amphibians are facing local and global declines (Fisher and Shaffer 1996;Houlahan et al 2000;Collins and Storfer 2003;Stuart et al 2004) and are often sensitive to anthropogenic habitat alteration (Guerry and Hunter 2002;Zamudio and Wieczorek 2007). Thus, studies linking breeding habitat and population persistence may play a critical role in conservation and management strategies (Gibbs 1998;Guerry and Hunter 2002;Funk et al 2005;Rittenhouse and Semlitsch 2006).…”

Section: Introductionmentioning

confidence: 99%

Effective population size is strongly correlated with breeding pond size in the endangered California tiger salamander, Ambystoma californiense

Wang

Johnson

et al. 2011

Conserv Genet

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Maintaining genetic diversity and population viability in endangered and threatened species is a primary concern of conservation biology. Genetic diversity depends on population connectivity and effective population size (N e ), both of which are often compromised in endangered taxa. While the importance of population connectivity and gene flow has been well studied, investigating effective population sizes in natural systems has received far less attention. However, N e plays a prominent role in the maintenance of genetic diversity, the prevention of inbreeding depression, and in determining the probability of population persistence. In this study, we examined the relationship between breeding pond characteristics and N e in the endangered California tiger salamander, Ambystoma californiense. We sampled 203 individuals from 10 breeding ponds on a local landscape, and used 11 polymorphic microsatellite loci to quantify genetic structure, gene flow, and effective population sizes. We also measured the areas of each pond using satellite imagery and classified ponds as either hydrologically-modified perennial ponds or naturally occurring vernal pools, the latter of which constitute the natural breeding habitat for A. californiense. We found no correlation between pond area and heterozygosity or allelic diversity, but we identified a strong positive relationship between breeding pond area and N e , particularly for vernal pools. Our results provide some of the first empirical evidence that variation in breeding habitat can be associated with differences in N e and suggest that a more complete understanding of the environmental features that influence N e is an important component of conservation genetics and management.

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Global amphibian declines: sorting the hypotheses

Cited by 835 publications

References 57 publications

Can the introduction of Xenopus laevis affect native amphibian populations? Reduction of reproductive occurrence in presence of the invasive species

Can the introduction of Xenopus laevis affect native amphibian populations? Reduction of reproductive occurrence in presence of the invasive species

Pesticide concentrations in frog tissue and wetland habitats in a landscape dominated by agriculture

Effective population size is strongly correlated with breeding pond size in the endangered California tiger salamander, Ambystoma californiense

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