Ongoing declines for the world's amphibians in the face of emerging threats.

Systematic assessments of species extinction risk at regular intervals are necessary for informing conservation action1,2. Ongoing developments in taxonomy, threatening processes and research further underscore the need for reassessment3,4. Here we report the findings of the second Global Amphibian Assessment, evaluating 8,011 species for the International Union for Conservation of Nature Red List of Threatened Species. We find that amphibians are the most threatened vertebrate class (40.7% of species are globally threatened). The updated Red List Index shows that the status of amphibians is deteriorating globally, particularly for salamanders and in the Neotropics. Disease and habitat loss drove 91% of status deteriorations between 1980 and 2004. Ongoing and projected climate change effects are now of increasing concern, driving 39% of status deteriorations since 2004, followed by habitat loss (37%). Although signs of species recoveries incentivize immediate conservation action, scaled-up investment is urgently needed to reverse the current trends.

Population dynamics of the critically endangered toad Atelopus cruciger and the fungal disease chytridiomycosis.

Harlequin toads (Atelopus) are among the most severely impacted amphibians by the emergence of chytridiomycosis, a fungal disease caused by the pathogen Batrachochytrium dendrobatidis (Bd). Many species disappeared while others suffered drastic contractions of their geographic distribution to lower altitudes. A diminished virulence of Bd in warm habitats was proposed to explain the survival of lowland populations of harlequin toads (i.e. thermal refuge hypothesis). To understand the mechanisms that allow some populations to reach an endemic equilibrium with this pathogen, we estimated demographic and epidemiological parameters at one remnant population of Atelopus cruciger in Venezuela using mark-recapture data from 2007-2013. We demonstrated that Bd is highly virulent for A. cruciger, increasing the odds of dying of infected adults four times in relation to uninfected ones and reducing the life expectancy of reproductive toads to a few weeks. Despite an estimated annual loss of 18% of the reproductive population due to Bd-induced mortality, this population has persisted in an endemic equilibrium for the last decade through the large recruitment of healthy adults every year. Given the high vulnerability of harlequin toads to Bd in lowland populations, thermal refuges need to be redefined as habitats of reduced transmission rather than attenuated virulence.

Aspectos ecológicos de una comunidad de bagres (Pisces: Siluroidei) en los Llanos inundables de Venezuela / Ecological aspects of a community of catfishes (Pisces: Siluroidei) in the flooded Llanos of Venezuela

Se estudio la composición, abundancia, biomasa, distribución espacial y temporal, ecología alimentaria y reproductiva de los peces Siluroidei de un río de aguas claras (Caño Guaritico) y planicie de inundación en los Llanos de Venezuela. Se identificaron 65 especies agrupadas en 10 familias y 52 géneros, representado el 34,5 por ciento de la ictiófauna registrada para la área (189 spp). 61 especies se encontraron en el Caño Guaritico, tributarios y plano inundable asociado a este y 27 en las áreas inundables periféricas de origen básicamente pluvial. 23 especies son comunes a ambos sistemas; 36 son exclusivas al canal principal del río y sólo 4 a las áreas inundables periféricas. Pimelodus blochii, Hypophthalmus edentatus y Loricariichtys maculatus fueron, en términos de abundancia y biomasa, las especies más importantes en las áreas inundables periféricas, mientras que en el canal principal del caño no se observaron especies claramente dominantes. Los análisis de contenido estomacal revelan cinco categorías tróficas: Detrívoros (9 spp), zooplactófagos (3 spp), omnívoro-insectívoro (15 spp), omnívoro-carnivoro (2 spp) y omnívoro-herbívoro (2 spp). Se observó cambios en la dieta debido a la estacionalidad climática. La mayoría de las especies se reproducen a principios o durante la época de lluvia o aguas altas, a excepción de los Loricariidae que parecen tener una reproducción continua. Se determinó la fecundidad de 23 especies