[Show abstract][Hide abstract] ABSTRACT: Globally, amphibians face many potential threats, including international trade. However, there is a lack of
knowledge regarding the types, levels and dynamics of the amphibian trade at the global scale. This study reviewed the trade in CITES-listed species between 1976 and2007. Four main trade groups (eggs, skins, meat and individuals) were identified. Trade in amphibian leather focused on Hoplobatrachus tigerinus 5,572individuals), whereas trade in eggs focused on Ambystoma mexicanum(6,027eggs). However, for the entire study period (1976–2007), trade in skins and eggs was small compared with trade in meat and live animals. The meat trade was estimated to be worth .USD111 million, whereas the trade in live animals was
estimated to be worth.USD11.5million in only three of the genera involved. Trade dynamics have changed as a
result of changes in legislation, such as a ban on H. tigerinus exports from Bangladesh for meat. Within the live trade 22species categorized as either Critically Endangered or Endangered were traded during the study period, and these require greater attention. International trade and potential conservation benefits are affected by countries supplying captive-bred individuals to their domestic markets as this trade goes unrecorded. However, this study only investigated trade in species listed by CITES, and other species may comprise a significant additional component of international trade. The trade in amphibians is dynamic, and changes in both the types of trade and the species concerned were identified over the study period. Conservation concerns have multiplied from issues concerning population depletions to include indirect impacts associated with disease, predation and competition, which requires a reappraisal of data capture and reporting.
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND: An understanding of the conservation status of Madagascar's endemic reptile species is needed to underpin conservation planning and priority setting in this global biodiversity hotspot, and to complement existing information on the island's mammals, birds and amphibians. We report here on the first systematic assessment of the extinction risk of endemic and native non-marine Malagasy snakes, lizards, turtles and tortoises.
METHODOLOGY/PRINCIPAL FINDINGS: Species range maps from The IUCN Red List of Threatened Species were analysed to determine patterns in the distribution of threatened reptile species. These data, in addition to information on threats, were used to identify priority areas and actions for conservation. Thirty-nine percent of the data-sufficient Malagasy reptiles in our analyses are threatened with extinction. Areas in the north, west and south-east were identified as having more threatened species than expected and are therefore conservation priorities. Habitat degradation caused by wood harvesting and non-timber crops was the most pervasive threat. The direct removal of reptiles for international trade and human consumption threatened relatively few species, but were the primary threats for tortoises. Nine threatened reptile species are endemic to recently created protected areas.
CONCLUSIONS/SIGNIFICANCE: With a few alarming exceptions, the threatened endemic reptiles of Madagascar occur within the national network of protected areas, including some taxa that are only found in new protected areas. Threats to these species, however, operate inside and outside protected area boundaries. This analysis has identified priority sites for reptile conservation and completes the conservation assessment of terrestrial vertebrates in Madagascar which will facilitate conservation planning, monitoring and wise-decision making. In sharp contrast with the amphibians, there is significant reptile diversity and regional endemism in the southern and western regions of Madagascar and this study highlights the importance of these arid regions to conserving the island's biodiversity.
PLoS ONE 01/2014; 9(8):e100173. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Effective conservation requires a step change in the way practitioners can contribute to science and can have access to research outputs. The journal Conservation Evidence was established in 2004 to help practitioners surmount several obstacles they face when attempting to document the effects of their conservation actions scientifically. It is easily and freely accessible online. It is free to publish in and it enables global communication of the effects of practical trials and experiments, which are virtually impossible to get published in most scientific journals. The driving force behind Conservation Evidence is the need to generate and share scientific information about the effects of interventions.
[Show abstract][Hide abstract] ABSTRACT: The Natterjack toad remains one of the best-studied amphibians
within Europe and much of the research conducted has had a direct
conservation focus. Long-term collaboration between researchers
and conservation practitioners in different countries has been a
hallmark of the programme, and the exchange of data and experiences
has been of mutual benefit.
[Show abstract][Hide abstract] ABSTRACT: Biodiversity monitoring programs need to be designed so that population changes can be detected reliably. This can be problematical for species that are cryptic and have imperfect detection. We used occupancy modeling and power analysis to optimize the survey design for reptile monitoring programs in the UK. Surveys were carried out six times a year in 2009-2010 at multiple sites. Four out of the six species--grass snake, adder, common lizard, slow-worm -were encountered during every survey from March-September. The exceptions were the two rarest species--sand lizard and smooth snake--which were not encountered in July 2009 and March 2010 respectively. The most frequently encountered and most easily detected species was the slow-worm. For the four widespread reptile species in the UK, three to four survey visits that used a combination of directed transect walks and artificial cover objects resulted in 95% certainty that a species would be detected if present. Using artificial cover objects was an effective detection method for most species, considerably increased the detection rate of some, and reduced misidentifications. To achieve an 85% power to detect a decline in any of the four widespread species when the true decline is 15%, three surveys at a total of 886 sampling sites, or four surveys at a total of 688 sites would be required. The sampling effort needed reduces to 212 sites surveyed three times, or 167 sites surveyed four times, if the target is to detect a true decline of 30% with the same power. The results obtained can be used to refine reptile survey protocols in the UK and elsewhere. On a wider scale, the occupancy study design approach can be used to optimize survey effort and help set targets for conservation outcomes for regional or national biodiversity assessments.
PLoS ONE 01/2012; 7(8):e43387. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Summary1. Altered global climates in the 21st century pose serious threats for biological systems and practical actions are needed to mount a response for species at risk.2. We identify management actions from across the world and from diverse disciplines that are applicable to minimizing loss of amphibian biodiversity under climate change. Actions were grouped under three thematic areas of intervention: (i) installation of microclimate and microhabitat refuges; (ii) enhancement and restoration of breeding sites; and (iii) manipulation of hydroperiod or water levels at breeding sites.3. Synthesis and applications. There are currently few meaningful management actions that will tangibly impact the pervasive threat of climate change on amphibians. A host of potentially useful but poorly tested actions could be incorporated into local or regional management plans, programmes and activities for amphibians. Examples include: installation of irrigation sprayers to manipulate water potentials at breeding sites; retention or supplementation of natural and artificial shelters (e.g. logs, cover boards) to reduce desiccation and thermal stress; manipulation of canopy cover over ponds to reduce water temperature; and, creation of hydrologoically diverse wetland habitats capable of supporting larval development under variable rainfall regimes. We encourage researchers and managers to design, test and scale up new initiatives to respond to this emerging crisis.
[Show abstract][Hide abstract] ABSTRACT: Mobilising volunteers to carry out biodiversity assessments can help to identify priorities for conservation across broad geographical scales. However, even when volunteers carry out simple presence–absence surveys, there can be significant issues over false absences and subsequent data interpretation. Simple but scientifically robust protocols are therefore required for these programmes. Here we evaluate amphibian survey protocols for the National Amphibian and Reptile Recording Scheme (NARRS) in Britain, which aims to assess the status of five widespread amphibian species. Surveys were undertaken by trained volunteers and researchers in two contrasting landscapes over 2 years, and occupancy modelling was used to determine covariates of detection, and to optimise the number of surveys and number of methods required. Although surveys need to take into account seasonal and annual changes in the detectability of different species, there were also landscape effects. Frogs and toads were generally harder to detect in ponds in Kent than in Wales, while the converse was true of newts. Adding bottle-trapping to the suite of methods increased the detection of smooth and palmate newts in both areas, and of great crested newts in Wales. Overall, reliable assessment of the presence or absence of all five species at a site required four separate surveys, each using four different methods (visual encounter surveys during both day and night, dip netting and bottle-trapping). Our approach may prove useful for finding the best compromises between rigor and simplicity when volunteers are used in large-scale surveys.
[Show abstract][Hide abstract] ABSTRACT: Climate can interact with population dynamics in complex ways. In this study we describe how climatic factors influenced the dynamics of an amphibian metapopulation over 12 years through interactions with survival, recruitment and dispersal. Low annual survival of great crested newts (Triturus cristatus) was related to mild winters and heavy rainfall, which impacted the metapopulation at the regional level. Consequently, survival varied between years but not between subpopulations. Despite this regional effect, the four subpopulations were largely asynchronous in their dynamics. Three out of the four subpopulations suffered reproductive failure in most years, and recruitment to the metapopulation relied on one source. Variation in recruitment and juvenile dispersal was therefore probably driving asynchrony in population dynamics. At least one subpopulation went extinct over the 12 year period. These trends are consistent with simulations of the system, which predicted that two subpopulations had an extinction risk of >50% if adult survival fell below 30% in combination with low juvenile survival. Intermittent recruitment may therefore only result in population persistence if compensated for by relatively high adult survival. Mild winters may consequently reduce the viability of amphibian metapopulations. In the face of climate change, conservation actions may be needed at the local scale to compensate for reduced adult survival. These would need to include management to enhance recruitment, connectivity and dispersal.
[Show abstract][Hide abstract] ABSTRACT: The feeding responses of three species of newt larvae were compared under circumneutral and sublethal acid conditions. Under acid conditions (pH 4.5) feeding behaviour was suppressed in palmate newts, Triturus helveticus, and smooth newts. T. vulgaris, but not in crested newts, T. cristatus. At low pH, approach and orientation towards food occurred in T. helveticus and T. vulgaris, but snapping was inhibited; T. cristatus snapped and consumed food immediately it was offered under the same conditions. These differences are not consistent with the apparent greater tolerance of T helveticus for acidified ponds. The observations suggest that the chemosensory system of T. helveticus and T. vulgaris may be impaired at low pH.
[Show abstract][Hide abstract] ABSTRACT: The distribution of smooth newts, Triturus vulgaris, and palmate newts, Triturus helveticus, in north-west Europe is related to geology and water quality. This study compared the development of the eggs and larvae of the two species under sublethal acidic and neutral conditions. Newt embryos raised under low pH hatched at an earlier stage of development, at a smaller size, and before those raised under neutral conditions. T. vulgaris hatched at a smaller size than T. helveticus, but pH did not affect the species differentially. Larvae of both species grew to a larger size under neutral than under acid conditions. Larvae raised in heterospecific pairs grew at least as well as those raised in conspecific pairs. Feeding was depressed under acid conditions, and reduced growth may therefore be associated with changes in the behaviour of newt larvae and their prey.
[Show abstract][Hide abstract] ABSTRACT: 2 Administration de la nature et des forêts, 16 rue Eugène Ruppert, L-2453 Luxembourg (firstname.lastname@example.org) Wood, L.R., R.A. Griffiths & L. Schley, 2009. Amphibian chytridiomycosis in Luxembourg. Bulletin de la Société des naturalistes luxembourgeois 110: 109-114. Abstract. Aquatic-phase amphibians at eight sites in Luxembourg were tested for the fungus Batrachochytrium dendrobatidis, which causes a disease responsible for population declines among many amphibian species worldwide. Infected amphibians were found at two of the sites tested; two further sites also showed marginally positive results. The ecology of B. den-drobatidis and the necessity for biosecurity protocol implementation by fieldworkers are discussed.
[Show abstract][Hide abstract] ABSTRACT: Small freshwater mussels are sometimes found attached to the toes of aquatic phase amphibians, but the ecological implications of this interspecific relationship are unknown. Toe condition and mussel presence were recorded for newts caught in 37 ponds in Luxembourg between March and June 2007. All four local newt species were affected (Lissotriton helveticus, L. vulgaris, Mesotriton alpestris and Triturus cristatus), primarily by the mussel Sphaerium nucleus but also by Pisidium subtruncatum. Mussel attachment was observed in three ponds, with a particularly high occurrence in one pond, where 23% of newts were affected and significantly more toes were damaged than in other ponds. Mussels caused local tissue and bone damage to their host and may interfere with egg-laying. Twenty-two newts with attached mussels were observed in aquaria for up to 3 days: 13 mussels detached when the newt's toe fell off and nine remained attached. If the mussels benefit from the interaction through, for example, enhanced dispersal then the relationship between the two taxa represents a novel form of parasitism.
[Show abstract][Hide abstract] ABSTRACT: The global amphibian crisis has resulted in renewed interest in captive breeding as a conservation tool for amphibians. Although captive breeding and reintroduction are controversial management actions, amphibians possess a number of attributes that make them potentially good models for such programs. We reviewed the extent and effectiveness of captive breeding and reintroduction programs for amphibians through an analysis of data from the Global Amphibian Assessment and other sources. Most captive breeding and reintroduction programs for amphibians have focused on threatened species from industrialized countries with relatively low amphibian diversity. Out of 110 species in such programs, 52 were in programs with no plans for reintroduction that had conservation research or conservation education as their main purpose. A further 39 species were in programs that entailed captive breeding and reintroduction or combined captive breeding with relocations of wild animals. Nineteen species were in programs with relocations of wild animals only. Eighteen out of 58 reintroduced species have subsequently bred successfully in the wild, and 13 of these species have established self-sustaining populations. As with threatened amphibians generally, amphibians in captive breeding or reintroduction programs face multiple threats, with habitat loss being the most important. Nevertheless, only 18 out of 58 reintroduced species faced threats that are all potentially reversible. When selecting species for captive programs, dilemmas may emerge between choosing species that have a good chance of surviving after reintroduction because their threats are reversible and those that are doomed to extinction in the wild as a result of irreversible threats. Captive breeding and reintroduction programs for amphibians require long-term commitments to ensure success, and different management strategies may be needed for species earmarked for reintroduction and species used for conservation research and education.
[Show abstract][Hide abstract] ABSTRACT: The effectiveness of flagship species as a conservation tool is controversial, and amphibians are not usually regarded as meeting the strategic criteria that flagships demand. Capitalizing on the historical, cultural and economic importance of the Axolotl Ambystoma mexica-num at Lake Xochimilco, Mexico, a conservation pro-gramme for this species and its habitat was developed using the Axolotl as a flagship. The threats to the lake are complex and stem from the unsustainable use of its re-sources. The needs and livelihoods of local stakeholders must therefore be taken into account before attempting to address the threats. The programme therefore focused on developing nature tourism by training local boatmen (remeros) in environmental interpretation. Surveys showed that the boatmen increased their incomes and job satisfaction after training, and that the environmental interpretation programme improved relevant knowledge and awareness of visitors. Although ongoing threats mean that reintroduction of captive-bred Axolotls is not appropriate, zoos with captive populations of Axolotls supported the programme regionally and internationally by providing publicity, funds, staff expertise, training support and themed educational activities. By raising both funds and awareness for the wider conservation of Lake Xochimilco, the Axolotl is probably the first amphibian flagship to be launched successfully.
[Show abstract][Hide abstract] ABSTRACT: On Jersey (British Channel Islands), common toads often reproduce in small, urban ponds. This atypical breeding strategy has implications for their persistence and they have declined on the island in recent times. We used polymorphic microsatellite markers to compare genetic diversity in Bufo bufo from five different ponds in Jersey with two populations from north-west France. Genetic diversity of Jersey toads was comparable with that of populations elsewhere in Europe. Numbers of breeding female toads in Jersey were correlated with pond area but estimators of genetic diversity were unrelated to pond area or female numbers. Fst estimates and isolation by distance tests indicated that there is little gene flow between breeding sites on the island. Jersey populations last shared a common ancestor with those of north-west France long before the island's physical separation about 6000 years ago. Toads have a long history in Jersey and were once probably very numerous there. The average effective historical population size of Jersey toads is estimated to be 15,000-16,000. Although genetic diversity of Jersey B. bufo is currently quite high, recent developments on the island may threaten this situation in the near future.
Herpetological Journal 06/2007; 17(of breeding female toads in Jersey were correlated with pond area but estimators of genetic diversity were unrelated to pond area or female numbers. Fst estimates and isolation by distance tests indicated that there is little gene flow between breeding sites on the island. Jersey populations last shared a common ancestor with those of north-west France long before the island's physical separation about 6000 years ago. Toads have a long history in Jersey and were once probably very numerous there. The average effective historical population size of Jersey toads is estimated to be 15):192-198. · 1.08 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We studied the diet of a population of free-ranging Mantella aurantiaca, an alkaloid-containing poison frog from Madagascar. As in other poison frogs, this species is thought to sequester alkaloids from arthropod prey. Among prey, mites and ants are known to regularly contain alkaloids and mites appear to be a major source of dietary alkaloids in poison frogs. We predicted that mites and ants would constitute the most important prey item for these frogs. Prey inventories were obtained during the rainy season by stomach flushing 23 adult male and 42 adult female frogs from one population. Males had smaller body sizes than females and ate smaller prey items, but males and females displayed no differences in the number of prey items consumed. The numerical proportion of ants in most specimens was surprisingly low (11% in males and 15% in females), while mites were slightly more frequent (34% in males and 18% in females). Other prey items consumed in large proportions were flies and collembolans. Comparing the total of 5492 arthropod prey items with 1867 arthropods sampled from the frogs' leaf litter habitat, the proportion of prey classes did not significantly differ among the samples, indicating a low degree of prey electivity in this population. Our data suggest that not all poison frogs exhibit a continuous and active preference for feeding on ants and mites, but instead some may consume high proportions of ants due to a high abundance of ants in their environment.
[Show abstract][Hide abstract] ABSTRACT: The impact of crested newts (Triturus cristatus) on the smaller-bodied palmate and smooth newts (T helveticus and T vulgaris) was studied during the larval stages using a combination of field and laboratory experiments In pond enclosures T cristatus larvae had no effect on the two smaller species over the first four weeks of development By eight weeks, however. T cristatus had achieved a size advantage which enabled it to eliminate T helveticus and severely reduce T vulgaris by predation In laboratory trials under food-limited conditions, T helveticus and T vulgaris were slightly smaller when raised with T cristatus, suggesting that this predatory effect was complemented by interspecific competition during early development Predation of the smaller species started when T cristatus reached a threshold size of c 27 mm No reciprocal effects on T cristatus growth or survival were observed Although T cristatus may be a significant predator of congeneric species in natural ponds, other factors, such as differences in microhabitat selection, higher-order predator-prey interactions and the occasional desiccation of pond habitats may facilitate coexistence between the species
[Show abstract][Hide abstract] ABSTRACT: SUMMARY1. Numbers of the contramensal alga Prototheca richardsi were high in spring in two ponds used for breeding by anuran amphibians, but lower at other times of year and undetectable in two ponds not used by anurans.2. Prototheca richardsi became abundant in the silt of eight experimental ponds which contained tadpoles, but remained undetectable in four otherwise identical ponds lacking tadpoles.3. Prototheca richardsi numbers in laboratory microcosms remained stable for many days in sterile tap water, but declined with a half-life of about 6 days in pond water at 20°C.4. Further studies with microcosms using antibiotics and electron microscopy indicated that mortality of P. richardsi was caused primarily by pathogenic bacteria.
[Show abstract][Hide abstract] ABSTRACT: Summary • Although captive breeding and reintroduction is a high-profile management tool for many threatened species, it is unclear how long-term captive breeding can influence fitness attributes such as natural defences to predators. • Induced defences that have evolved in the Mallorcan midwife toad Alytes muletensis in response to introduced predators were compared in natural and reintroduced populations that had a common ancestry, and in short-term and long-term captive populations that differed in ancestry. • Defences against predators were maintained in a reintroduced population derived from stock that had passed through three to eight generations of captive breeding prior to release into a predator-free area. Heterozygosity did not differ between natural and reintroduced populations, but the reintroduced population displayed lower allelic richness. • A comparison between populations maintained for different lengths of time in captivity revealed a significant reduction in one defensive trait in stock maintained for more than eight generations. Neutral genetic variation (i.e. heterozygosity and allelic richness) did not differ between the short-term captive population and a natural population, but there was a significant loss of genetic variation in the long-term captive population. • Synthesis and applications. The results suggest that relatively high levels of heterozygosity and important fitness attributes can be maintained for a few generations in breeding programmes for threatened species despite small numbers of founders and the absence of natural selection. Nevertheless, both fitness and heterozygosity may eventually start to deteriorate in the long term, and this may have implications for reintroduction strategies. Journal of Applied Ecology (2006) 43, 360 –365 doi: 10.1111/j.1365-2664.2006.01137.x