Visual implant elastomer (VIE) tags are an unreliable method of identification in adult anurans

There has long been debate over alternatives to toe-clipping as an individual marking method in anurans. Alternative methods include visible implant elastomer (VIE) tags and passive integrated transponder (PIT) tags. VIE tags are low cost, easy to insert and have been used successfully in reptiles, fish and salamanders without tag loss or movement. In this study, we tested whether two species of VIE-tagged anurans (captive Kihansi spray toads, Nectophrynoides asperginis, and leopard frogs Lithobates pipiens) experienced tag movement or loss that could lead to errors in individual identification. VIE tag movement occurred in 50% of the tags implanted which caused 70.6% of individuals to be potentially misidentified. These results demonstrate that the use of VIE tags to individually mark anurans can be highly unreliable. We therefore recommend either verifying the reliability of VIE tags through species- and life stage-specific pilot studies, or choosing another method of marking

Batrachochytrium dendrobatidis in natural and farmed Louisiana crayfish populations: prevalence and implications

The pathogenic chytrid fungus Batrachochytrium dendrobatidis (Bd) has been linked to global declines and extinctions of amphibians, making it one of the most devastating wildlife pathogens known. Understanding the factors that affect disease dynamics in this system is critical for mitigating infection and protecting threatened species. Crayfish are hosts of this pathogen and can transmit Bd to amphibians. Because they co-occur with susceptible amphibian communities, crayfish may be important alternative hosts for Bd. Understanding the prevalence and seasonal dynamics of crayfish infections is of agricultural and ecological interest in areas where crayfish are farmed and traded for human consumption. We conducted a survey of Bd in farmed and natural crayfish (Procambarus spp.) populations in Louisiana, USA. We found that Bd prevalence and infection intensity was low in both farmed and native populations and that prevalence varied seasonally in wild Louisiana crayfish. This seasonal pattern mirrors that seen in local amphibians. As crayfish are an important globally traded freshwater taxon, even with low prevalence, they could be an important vector in the spread of Bd

Fungal infection has sublethal effects in a lowland subtropical amphibian population

Abstract Background The amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), has been implicated as a primary cause of decline in many species around the globe. However, there are some species and populations that are known to become infected in the wild, yet declines have not been observed. Here we conducted a yearlong capture-mark-recapture study and a 2-year long disease monitoring study of northern cricket frogs, Acris crepitans, in the lowland subtropical forests of Louisiana. Results We found little evidence for an impact of Bd infection on survival; however, Bd infection did appear to cause sublethal effects, including increased capture probability in the field. Conclusions Our study suggests that even in apparently stable populations, where Bd does not appear to cause mortality, there may be sublethal effects of infection that can impact a host population’s dynamics and structure. Understanding and documenting such sublethal effects of infection on wild, seemingly stable populations is important, particularly for predicting future population declines

Map of field sites in southeastern Louisiana.

<p>Black circles indicate sites where only <i>H. cinerea</i> was sampled. White circles with black outlines indicate sites where <i>H. cinerea</i> and other species were sampled. White circles with no outline indicate sites where only other species (no <i>H. cinerea</i>) were sampled. Site numbers correspond to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0038473#pone-0038473-t001" target="_blank">Tables 1</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0038473#pone.0038473.s001" target="_blank">S1</a>.</p

Body condition does not differ between frogs infected with different strains of <i>Bd</i>.

<p>SRS810 infected individuals: grey. JEL423 infected individuals: black. Body condition was measured mass (g) divided by SVL (mm). Week indicates the number of weeks after last inoculation. Error bars are ± one standard error of the mean.</p