Eco-engineering hope for amphibians

"An international team of researchers have tabled a range of engineering ideas that could help protect amphibians from future climate change. The animals are particularly vulnerable to changes to habitat and temperature ranges, with many species also having a very limited distribution. The scientists plan to test their ideas to see which ones are the most suitable and cost effective.
One of the possible solutions was to create "micro-habitat shelters". For example, this could included forestry operators leaving a pile of dead wood, rather than clearing an entire area, so it offered protection to amphibians from drying out and temperature stress."

Read more: BBC News - Eco-engineering hopes for amphibians' future

Engineering a future for amphibians under climate change. Journal of Applied Ecology, doi: 10.1111/j.1365-2664.2010.01942.x

Aint got no good news today. Here is the bad news

"Ranaviruses are non-zoonotic viruses (i.e. don't infect humans) of the Iridovirus family that mainly affect amphibians, but there are also reports in fishes and turtles. Ranavirus infection was first described in 1966 but not associated with disease until the 1980's, when mass die-offs of frogs were 1st seen. Ranavirus has now been reported on every continent except Africa.
The mode of transmission is via contaminated water. The most common presentation is an explosive mortality event with death due to peracute systemic haemorrhagic disease. In these cases, usually there are no external lesions. Diagnosis is by virus culture followed by identification using electron microscope or PCR. There is currently no known prevention or control method.
A study in the UK has confirmed that ranavirus not only causes sudden
mass-mortality events, but also long term population declines. The
researchers examined wild common frog (Rana temporaria) numbers in a
selection of populations around the country where ranavirus disease
had been previously reported since 1996. The finding was that half of
the populations has had repeated outbreaks of the disease. In almost a
quarter of the cases, frog numbers had dropped by 81 percent over the
last 12 years."

Read more: RANAVIRUS, FROG - NETHERLANDS: OIE

Drying out the cane toad invasion

"In June 1935, the cane toad began its invasion of Australia. Sailors brought the animal over from Hawaii in an attempt to control the cane beetle that was ravaging Australia’s sugar cane crops. It was a mistake that the continent’s wildlife would pay for. The toad did nothing to stop the beetles. Instead, it launched its own invasion, spreading across the continent from its north-eastern point of entry. As it marched, it left plummeting populations of native species in its wake.
The toads are born conquerors. Females can lay 35,000 eggs many times a year, and each can develop into a new frog in less than 10 weeks. They’re unfussy eaters and they’ll munch away on bird eggs, smaller native frogs and more. And they have large glands behind their heads, which secrete a milky poison. Local predators (or domestic pets) that try to eat them tend to die.
Now, Daniel Florance from the University of Sydney has found a clever way of corralling the cane toad invasion. He realised that humans have continued to give the toad a hand, long after we first brought them to Australia. By creating dams and troughs, we provided the toad with watery staging grounds that allowed it to spread across otherwise impassably dry land."

Read more: Drying out the cane toad invasion | Not Exactly Rocket Science

Solving the mystery of the deformed frogs

"For the last two decades, strange things have been happening to frogs. Some frog populations have high rates of limb deformities, while others have high incidences of what is known as 'intersex' — traits associated with both males and females, such as male frogs whose testes contain eggs. David K. Skelly, professor of ecology at the Yale School of Forestry & Environmental Studies, set out to discover what was causing these deformities, which some researchers were attributing to the use of an agricultural pesticide called atrazine. Skelly launched an experiment in ponds throughout Connecticut, studying frogs in four landscapes: forests, agricultural areas, suburbs, and cities. And what he found was surprising — the highest rates of deformities were not occurring in and around farmlands, but in cities and suburbs."

Read more: Solving the mystery of the bizarre deformed frogs | guardian.co.uk

Promiscuity pays

One of nature’s biggest mysteries is why some females mate with multiple males (polyandry) despite the risk of disease transmission, potential injury and even increased predation risk. In externally fertilizing animals, including some species of fish and frogs, females can mate with multiple males at the same time (simultaneous polyandry).
Scientists investigated whether simultaneous polyandry influences offspring fitness in a wild population of the African Grey Foam Nest Treefrog (Chiromantis xerampelina). Simultaneous polyandry in this frog is the most extreme reported for any vertebrate, with more than 90% of females mating with 10 or more males during the deposition of a single clutch. They compared growth (using age and size at metamorphosis as proxies) and survival of offspring produced by females that naturally mated with either one male (monandrous females) or 10–12 males (polyandrous females). Polyandry did not influence size or age at metamorphosis, but offspring from polyandrous matings had significantly higher mean survival.
Their findings implicate a genetic benefit to females mating with multiple males, and suggest that females are advantaged by mating promiscuously.

Read more: Promiscuity pays in the frog world

Worldwide search for 'lost frogs' ends with 4% success, but some surprises

"The Search for Lost Frogs conducted by Conservation International (CI), the IUCN Amphibian Specialist Group (ASG), and Global Wildlife Conservation (GWC), hoped to find species whose status remained unknown. The unprecedented search did uncover surviving populations of the Cave Splayfoot Salamander (Chiropterotriton mosaueri) of Mexico (not seen since 1941), the Mount Nimba Reed Frog (Hyperolius nimbae) of Ivory Coast (last seen in 1967), and the Omaniundu Reed Frog (Hyperolius sankuruensis) of Democratic Republic of Congo (not seen since 1979). In addition the search announced today that it also rediscovered the Rio Pescado stubfoot toad of Ecuador (to read more about this discovery: Researchers rediscover one of the world's most sought-after lost frogs). This find was especially gratifying as the toad was the only rediscovered amphibian on the Search's Top Ten List (ranked number six). After being tipped off by a local community, the researchers found a single adult toad."

Read more: Worldwide search for 'lost frogs' ends with 4% success, but some surprises

Pesticides and frog population declines

Atmospherically deposited pesticides from the intensively cultivated Central Valley of California, USA, have been implicated as a cause for population declines of several amphibian species, with the strongest evidence for the frogs Rana muscosa and Rana sierrae at high elevation in the Sierra Nevada mountains. Previous studies on these species have relied on correlations between frog population status and either a metric for amount of upwind pesticide use or limited measurements of pesticide concentrations in the field. The present study tested the hypothesis that pesticide concentrations are negatively correlated with frog population status (i.e. fraction of suitable water bodies occupied within 2 km of a site) by measuring pesticide concentrations in multiple media twice at 28 sites at high elevation in the southern Sierra Nevada. Media represented were air, sediment, and Pseudacris sierra tadpoles. Total cholinesterase (ChE), which has been used as an indicator for organophosphorus and carbamate pesticide exposure, was also measured in P. sierra tadpoles. Results do not support the pesticide-site occupancy hypothesis. Among 46 pesticide compounds analyzed, nine were detected with ≥30% frequency, representing both historically and currently used pesticides. In stepwise regressions with a chemical metric and linear distance from the Central Valley as predictor variables, no negative association was found between frog population status and the concentration of any pesticide or tadpole ChE activity level. By contrast, frog population status showed a strong positive relationship with linear distance from the Valley, a pattern that is consistent with a general west-to-east spread across central California of the amphibian disease chytridiomycosis observed by other researchers.

Pesticide distributions and population declines of California, USA, alpine frogs, Rana muscosa and Rana sierrae. Environ Toxicol Chem. 2011 Mar;30(3):682-91. doi: 10.1002/etc.425. Jan 5 2011


What does this mean?
Although this study did not find a link between the pesticides examined, many other studies have, e.g. this one.

Eating them doesn't help

Species of frogs in the genus Telmatobius are traded and sold for human consumption in the Andes and in coastal cities of Peru and Bolivia. These frogs are harvested from wild populations. We report high prevalence of infection by the pathogenic fungus Batrachochytrium dendrobatidis in live frogs purchased at the main market in Cusco, Peru, from January 2008 to January 2010. We suggest that the transport of native anurans through the live frog trade could facilitate the spread of this fungus among Andean frogs. The tropical Andes are the most important biodiversity hotspot for amphibians. Because many neotropical taxa are known to be susceptible to chytridiomycosis, the presence of a large reservoir of infection in the frog trade poses a significant threat to amphibian conservation.

Batrachochytrium dendrobatidis in the live frog trade of Telmatobius (Anura: Ceratophryidae) in the tropical Andes

Meet Dirk Diggler: spawn star, sex god and saviour of his species

"It was a hot summer night in 1998 when a solitary spotted tree frog named Dirk went out looking for love. The fertile young male climbed down to a riverbank and began chirping his seductive, distinctive mating call. But there was no answer. Dirk was the last of his kind in the last spotted tree frog colony in NSW, tucked away in a corner of Kosciuszko National Park. All the rest had died of chytrid fungus, an introduced skin disease that has ravaged frog populations across Australia. Without females to respond to his mating song, Dirk's future was bleak. Fortunately other ears were listening."

Meet Dirk Diggler: spawn star, sex god and saviour of his species

Madagascar frog rears tadpoles in dead palm leaves

A new species of frog has been discovered that lays its eggs and grows its tadpoles in dead leaves that litter the forest floor. The frog, found in the rainforest of Madagascar, is the first amphibian known to reproduce in this way. Other species reproduce in water that collects or pools within plants, but the new frog is the first discovered to rear its young in fallen leaves. Scientists have called the new species Blommersia angolafa.

BBC News

Conservation Biology for All

This book contains a series of authoritative chapters have been written by the top names in conservation biology with the principal aim of disseminating cutting-edge conservation knowledge as widely as possible. Important topics such as balancing conversion and human needs, climate change, conservation planning, designing and analyzing conservation research, ecosystem services, endangered species management, extinctions, fire, habitat loss, and invasive species are covered. Numerous textboxes describing additional relevant material or case studies are also included.

Conservation Biology for All has been generously made available in it's entirety here.

Saving lives, salamander style

The Effects Of Climate Change Wildlife And Terrestrial Ecosystems

Climate change and biodiversity are interconnected. Unsustainable human activities that increase accumulation of greenhouse gases and hinder the natural balance of atmospheric greenhouse gases aggravate the effects of climate change on biodiversity. Rising seas-levels could inundate coastal habitats and stem the flow of nutrients from the ocean to the terrestrial ecosystems. Altered climate regimes directly affect wildlife, their behavior, migration, foraging, growth and reproduction. Climate change could disturb the dynamic equilibrium of terrestrial ecosystems by affecting ecosystem productivity, biomass production, hydrological balance, and trophic interactions. Further, climate change intensifies natural disasters and shifts in natural disturbance regimes. Such processes impose physiological and environmental stress on terrestrial ecosystems which adversely affect the ecosystem resistance and resilience. Moreover, warming atmosphere causes thermal optima to shift towards high latitudes and high altitudes. Terrestrial biota readily responds to temperature, where both flora and fauna alter distributions toward more favorable climatic conditions. Some climatic parameters that drive life history events, such as photoperiod, are fixed, while others, such as the timing of spring weather, are changing because of greenhouse gasses. The resulting mismatch between fixed and variable drivers of phenology, such as in mating, breeding, migration, hibernation, and post-hibernation activities, will disadvantage some species and benefit others. This will result in new ecosystems. Warming temperature favors biological activities of wildlife pathogens, since high temperature increases breeding rate, survival, hatching success and transmission of wildlife parasites and disease-causing agents. Climate change dissociates species interactions, mutual associations and a multitude of ecosystem functions. Ultimately, climate change predisposes native terrestrial wildlife to extinction and alters the functions and structure of terrestrial ecosystems. Biodiversity provides ecosystem services including the regulation and mitigation of the adverse impacts of climate change. Therefore, biodiversity conservation and terrestrial ecosystem management is critical to address climate change. Robust climate-oriented models with the use of GIS and remote sensing technology are needed to make effective predictions about the spatial and temporal effects of climate change.

The Effects Of Climate Change On Global Wildlife And Terrestrial Ecosystems. (2010) Taprobanica ISSN 1800-427X 2(1) 30-47

Effects of Chytrid Infectious Fungus on Amphibian Predator-Prey Interactions

The effects of parasites and pathogens on host behaviors may be particularly important in predator-prey contexts, since few animal behaviors are more crucial for ensuring immediate survival than the avoidance of lethal predators in nature. We examined the effects of an emerging fungal pathogen of amphibians, Batrachochytrium dendrobatidis, on anti-predator behaviors of tadpoles of four frog species. We also investigated whether amphibian predators consumed infected prey, and whether B. dendrobatidis caused differences in predation rates among prey in laboratory feeding trials. We found differences in anti-predator behaviors among larvae of four amphibian species, and show that infected tadpoles of one species (Anaxyrus boreas) were more active and sought refuge more frequently when exposed to predator chemical cues. Salamander predators consumed infected and uninfected tadpoles of three other prey species at similar rates in feeding trials, and predation risk among prey was unaffected by B. dendrobatidis. Collectively, our results show that even sub-lethal exposure to B. dendrobatidis can alter fundamental anti-predator behaviors in some amphibian prey species, and suggest the unexplored possibility that indiscriminate predation between infected and uninfected prey (i.e. non-selective predation) could increase the prevalence of this widely distributed pathogen in amphibian populations. Because one of the most prominent types of predators in many amphibian systems is salamanders, and because salamanders are susceptible to B. dendrobatidis, our work suggests the importance of considering host susceptibility and behavioral changes that could arise from infection in both predators and prey.

Effects of an Infectious Fungus, Batrachochytrium dendrobatidis, on Amphibian Predator-Prey Interactions. (2011) PLoS ONE 6(2): e16675. doi:10.1371/journal.pone.0016675

 

Mild mannered amphibians pack a poisonous wallop

"Though adult newts possess tetrodotoxin- a deadly neurotoxin concentrated on their skin and in their ovaries, muscles, and blood, a thorough hand-washing effectively removes traces of the toxin from human skin. The only documented reports of human fatalities have been related to ingestion of the creatures. Some reports of sickness have been documented from toxins entering the body through open wounds. Apparently the unfortunate victims didn't heed nature's warning: the combination of a bright reddish-orange underbelly along with a disgusting taste- generally an indicator that dinner would best be procured elsewhere."

Mild mannered amphibians pack a poisonous wallop