Amfibie: Algemeen

  • World’s Reptile Populations Running Thin

    World’s Reptile Populations Running Thin

    Reptiles worldwide may be under greater environmental stress than their amphibian cousins, according to a report published in the journal BioScience. Amphibian declines have garnered much attention within the scientific community over the last 10 years. Declines of reptiles, often linked to amphibians, warrant attention on their own, the authors note. “Recent research has demonstrated that amphibians are declining on a global scale,” said Whit Gibbons, a herpetologist and professor of ecology at the University of Georgia and lead author of the study. “We wanted to examine the same kind of evidence for reptiles as no one had yet synthesized the information to see if reptiles are facing similar problems.” According to the researchers, government records show that reptiles are vanishing faster than amphibians. More reptiles face environmental problems based on the numbers of endangered and threatened species identified by the U.S. Fish and Wildlife Service, they point out. The Wildlife Service lists 26 species of amphibians and 88 species of reptiles under the Endangered Species Act. Likewise, the World Conservation Union lists 129 amphibians and more than 270 reptiles around the world as endangered or vulnerable.

    Reptiles worldwide may be under greater environmental stress than their amphibian cousins, according to a report published in the journal BioScience. Amphibian declines have garnered much attention within the scientific community over the last 10 years. Declines of reptiles, often linked to amphibians, warrant attention on their own, the authors note. “Recent research has demonstrated that amphibians are declining on a global scale,” said Whit Gibbons, a herpetologist and professor of ecology at the University of Georgia and lead author of the study. “We wanted to examine the same kind of evidence for reptiles as no one had yet synthesized the information to see if reptiles are facing similar problems.” According to the researchers, government records show that reptiles are vanishing faster than amphibians. More reptiles face environmental problems based on the numbers of endangered and threatened species identified by the U.S. Fish and Wildlife Service, they point out. The Wildlife Service lists 26 species of amphibians and 88 species of reptiles under the Endangered Species Act. Likewise, the World Conservation Union lists 129 amphibians and more than 270 reptiles around the world as endangered or vulnerable.

    Using the six categories of concern established by the Partners in Amphibian and Reptile Conservation habitat loss and degradation, invasive species, environmental pollution, disease, unsustainable use and global climate change the authors explored the decline of reptiles. According to the report, amphibians and reptiles occupy similar habitat and are equally vulnerable to habitat degradation. “Amphibians and reptiles are correspondingly defenseless against the global threats of deforestation, draining of wetlands and pollution from agricultural run-off,” the authors note. Nevertheless, they point out that reptiles tend to occupy larger home ranges. “Reptiles require more space so they may be more susceptible to habitat fragmentation,” said co-author Travis Ryan, an assistant professor of biology at Forman University. Unsustainable human use may also pose a greater threat to reptiles. A dramatic example is the decline of leatherback sea turtles (Dermochelys coriacea), , Ryan said. “Leatherback populations have dropped to 30 percent of what they were 15 to 20 years ago.” “Reptiles probably face greater threats in the food trade,” said co-author Kurt Buhlmann, an ecologist with Conservation International. It is important to understand the life history of reptiles in the context of harvesting them for pet food and medicine, Buhlmann said. “Many reptiles don’t reproduce until later in life,” he explained. “Some turtles don’t reach sexual maturity until they are 18. You can’t think of reptiles as deer or rabbits that reproduce very quickly.” “This is a wake up call that reptiles are in trouble,” Buhlmann said. “If you look at the big picture, we’ve got problems. “Reptiles are a significant environmental component of virtually all temperate and tropical regions of the world,” added Gibbons. “They are at the top of the food pyramid in many systems and are therefore indicators of environmental health. Their loss from an ecosystem is a signal that the system is failing.”

    Source:
    Environmental News Network, August 11, 2000
    http://www.anapsid.org/popdecline.html

  • Amphibian and reptile declines over 35 years at La Selva, Costa Rica

    Amphibian and reptile declines over 35 years at La Selva, Costa Rica

    Amphibians stand at the forefront of a global biodiversity crisis. More than one-third of amphibian species are globally threatened, and over 120 species have likely suffered global extinction since 1980. Most alarmingly, many rapid declines and extinctions are occurring in pristine sites lacking obvious adverse effects of human activities. The causes of these “enigmatic” declines remain highly contested. Still, lack of long-term data on amphibian populations severely limits our understanding of the distribution of amphibian declines, and therefore the ultimate causes of these declines. Here, we identify a systematic community-wide decline in populations of terrestrial amphibians at La Selva Biological Station, a protected old-growth lowland rainforest in lower Central America. We use data collected over 35 years to show that population density of all species of terrestrial amphibians has declined by ≈75% since 1970, and we show identical trends for all species of common reptiles. The trends we identify are neither consistent with recent emergence of chytridiomycosis nor the climate-linked epidemic hypothesis, two leading putative causes of enigmatic amphibian declines.

    Amphibians stand at the forefront of a global biodiversity crisis. More than one-third of amphibian species are globally threatened, and over 120 species have likely suffered global extinction since 1980. Most alarmingly, many rapid declines and extinctions are occurring in pristine sites lacking obvious adverse effects of human activities. The causes of these “enigmatic” declines remain highly contested. Still, lack of long-term data on amphibian populations severely limits our understanding of the distribution of amphibian declines, and therefore the ultimate causes of these declines. Here, we identify a systematic community-wide decline in populations of terrestrial amphibians at La Selva Biological Station, a protected old-growth lowland rainforest in lower Central America. We use data collected over 35 years to show that population density of all species of terrestrial amphibians has declined by ≈75% since 1970, and we show identical trends for all species of common reptiles. The trends we identify are neither consistent with recent emergence of chytridiomycosis nor the climate-linked epidemic hypothesis, two leading putative causes of enigmatic amphibian declines.

    Source:
    Steven M. Whitfield et al. PNAS, pp. 8352–8356
    http://www.pnas.org/content/104/20/8352.abstract

  • Gefahr durch Pestizide für Frösche weitgehend unterschätzt

    Gefahr durch Pestizide für Frösche weitgehend unterschätzt

    Aktuelle Untersuchung an sieben zugelassenen Mitteln zeigt bei Grasfröschen Sterblichkeitsraten von 20 bis 100 Prozent.
    Der Kontakt mit Pflanzenschutzmitteln kann für Frösche tödlich sein – wie gefährlich die Gifte teilweise für die Amphibien sind, wurde bisher aber offenbar unterschätzt. Eine aktuelle deutsche Studie hat nun aufgedeckt, dass schon der Einsatz der empfohlenen Produktmenge bei Grasfröschen (Rana temporaria) zu Sterblichkeitsraten von 20 bis 100 Prozent führt. Die Gefahr besteht für alle sieben getesteten Mittel – ob Fungizid, Herbizid oder Insektizid. Zugelassen sind sie trotzdem, da das entsprechende Verfahren bislang mögliche Auswirkungen auf Amphibien (Lurche) nicht untersucht. “Es ist kaum fassbar, dass es bei Pestiziden, die das aktuell praktizierte Zulassungsverfahren für Pestizide durchlaufen haben, zu direkter Mortalität bei Amphibien kommt”, sagt Carsten Brühl, Leiter der Studie des Instituts für Umweltwissenschaften an der Universität Koblenz-Landau. “Unsere Laborversuche zeigen eine derartige Wirkung auf an Land lebende Entwicklungsstadien der Tiere. Dieser in der Risikobewertung bislang nicht berücksichtigte Effekt sollte in den Schutzbemühungen von Frosch- und Krötenpopulationen Berücksichtigung finden.”

    Aktuelle Untersuchung an sieben zugelassenen Mitteln zeigt bei Grasfröschen Sterblichkeitsraten von 20 bis 100 Prozent.
    Der Kontakt mit Pflanzenschutzmitteln kann für Frösche tödlich sein – wie gefährlich die Gifte teilweise für die Amphibien sind, wurde bisher aber offenbar unterschätzt. Eine aktuelle deutsche Studie hat nun aufgedeckt, dass schon der Einsatz der empfohlenen Produktmenge bei Grasfröschen (Rana temporaria) zu Sterblichkeitsraten von 20 bis 100 Prozent führt. Die Gefahr besteht für alle sieben getesteten Mittel – ob Fungizid, Herbizid oder Insektizid. Zugelassen sind sie trotzdem, da das entsprechende Verfahren bislang mögliche Auswirkungen auf Amphibien (Lurche) nicht untersucht. “Es ist kaum fassbar, dass es bei Pestiziden, die das aktuell praktizierte Zulassungsverfahren für Pestizide durchlaufen haben, zu direkter Mortalität bei Amphibien kommt”, sagt Carsten Brühl, Leiter der Studie des Instituts für Umweltwissenschaften an der Universität Koblenz-Landau. “Unsere Laborversuche zeigen eine derartige Wirkung auf an Land lebende Entwicklungsstadien der Tiere. Dieser in der Risikobewertung bislang nicht berücksichtigte Effekt sollte in den Schutzbemühungen von Frosch- und Krötenpopulationen Berücksichtigung finden.”

    Amphibien sind die am stärksten gefährdeten Wirbeltiere weltweit. Als mögliche Ursachen werden der Wettbewerb mit eingewanderten Arten, erhöhte UV-Strahlung, die globale Klimaerwärmung, ansteckende Krankheiten sowie der Verlust an Lebensraum diskutiert. Bislang nicht beachtet wird der Einfluss von Pestiziden. Dies liegt daran, dass die Untersuchung möglicher Effekte bislang nur unzureichend erfolgte und nicht Bestandteil des Zulassungsverfahrens für Pflanzenschutzmittel ist. Zurzeit werden nur Auswirkungen auf Vögel und Säugetiere sowie auf in Gewässern lebende Organismen getestet. Auch bei Vögeln und Säugetieren gibt es seit längerer Zeit die Diskussion, ob Pestizide über die Haut aufgenommen werden und wie groß die dadurch bedingte Gefahr ist. Die feuchte Haut von Fröschen absorbiert Stoffe in viel größeren Mengen, da sie im direkten Kontakt mit der Umwelt steht. Daher ist die Gefahr der so genannten dermalen Exposition hoch. Während die Zulassungsverfahren für Pestizide im Rahmen von Gewässeruntersuchungen Kaulquappen berücksichtigen, gilt dies nicht für die erwachsenen Frösche. Hier galt bislang die Einschätzung, dass für Vögel und Säugetiere unbedenkliche Mengen auch bei Fröschen kein großes Problem darstellen. Diese Haltung muss jedoch grundlegend überdacht werden. Schließlich führen bereits die empfohlenen Einsatzmengen des Fungizids “Headline” im Laborversuch bei juvenilen Grasfröschen innerhalb einer Stunde zu einer Sterblichkeitsrate von 100 Prozent. Da jedoch ein anderes Mittel, das die gleiche Menge des Wirkstoffs enthält, nur zu 20 Prozent tödlich ist, liegt die Gefahr wohl eher in den jeweils verwendeten Zusatzstoffen oder deren Konzentration. Welche Stoffe dies sind und wie sie wirken, ist jedoch noch völlig unklar und bedarf weiterer Forschungen. Dies gilt auch für die möglichen Effekte der Pestizide auf Freiland-Populationen. “Unsere Studie zeigt aber, dass schon jetzt dringender Handlungsbedarf besteht”, so Brühl weiter. “Auch Landwirte haben schließlich ein großes Interesse an einer intakten Natur und wollen Amphibien schützen, die schädliche Insekten vertilgen. Sie wollen daher Pestizide einsetzen, die diese nicht gefährden.” Ebenso sollten sich die für die Risikobewertung für Pestizide Verantwortlichen mit diesem Thema auseinandersetzen und Amphibien in ihre Betrachtung einschließen.

    Quelle: Der Standard, 26.01.2013
    http://derstandard.at/1358304594653/Gefahr-durch-Pestizide-fuer-Froesche-weitgehend-unterschaetzt

  • “Pesticiden kunnen kikkers binnen het uur doden”

    “Pesticiden kunnen kikkers binnen het uur doden”

    Nieuw onderzoek veronderstelt dat pesticiden en andere chemicaliën een significante rol spelen in de wereldwijde achteruitgang van amfibieën. Dat schrijft de Britse krant The Guardian. De wetenschappers achter de studie zeggen dat het zowel “verbazingwekkend” als “alarmerend” is dat veelvoorkomende pesticiden zo giftig kunnen zijn, en dat in dosissen die goedgekeurd zijn door overheden. De onderzoekers uiten ook kritiek op hoe de pesticiden getest worden. “Je zou niet denken dat producten, die geregistreerd zijn op de markt, zo’n giftig effect hebben”, zegt Carsten Brühl van de Duitse universiteit Koblenz-Landau. “Het is het simpelste effect dat je je kan inbeelden: je spuit de pesticide op de amfibie en die sterft. Dat moet zich vertalen in een dramatisch effect op gehele populaties.”

    Nieuw onderzoek veronderstelt dat pesticiden en andere chemicaliën een significante rol spelen in de wereldwijde achteruitgang van amfibieën. Dat schrijft de Britse krant The Guardian. De wetenschappers achter de studie zeggen dat het zowel “verbazingwekkend” als “alarmerend” is dat veelvoorkomende pesticiden zo giftig kunnen zijn, en dat in dosissen die goedgekeurd zijn door overheden. De onderzoekers uiten ook kritiek op hoe de pesticiden getest worden. “Je zou niet denken dat producten, die geregistreerd zijn op de markt, zo’n giftig effect hebben”, zegt Carsten Brühl van de Duitse universiteit Koblenz-Landau. “Het is het simpelste effect dat je je kan inbeelden: je spuit de pesticide op de amfibie en die sterft. Dat moet zich vertalen in een dramatisch effect op gehele populaties.”

    De populatie van amfibieën gaat het snelst achteruit van alle gewervelde diersoorten. Meer dan een derde van alle amfibieën staat op de rode lijst van bedreigde diersoorten. De grootste oorzaken zijn het verlies van de natuurlijke habitat, de klimaatsverandering en ziektes. Onderzoeker Brühl had eerder al bestudeerd hoe gemakkelijk amfibieën pesticiden absorberen door hun doordringbare huid, waardoor ze onderwater kunnen ademen. “Maar het is niet verplicht om pesticiden op amfibieën te testen”, zegt Brühl. Het team onderzocht een reeks wijdverspreide producten. De meest ontzettende resultaten kwamen er van de fungicide pyraclostrobin, die door BASF verkocht wordt als het product Headline. De fungicide wordt wereldwijd op 90 verschillende gewassen gebruikt. De wetenschappers voerden testen uit op alle veelvoorkomende Europese kikkers en die stierven binnen het uur. En dat bij de dosis die op het etiket werd toegelaten. Andere fungiciden, herbiciden en pesticiden bleken ook acuut giftig, zelfs al werd er maar 10 procent van de wettelijke dosis gebruikt. Daarbij vonden bijvoorbeeld 40 procent van de dieren de dood binnen de week. Een woordvoerder van BASF trekt de bevindingen van de studie in twijfel: “Dit onderzoek werd gevoerd onder ‘worst-case’-omstandigheden. Onder de normale omstandigheden in de landbouw worden amfibieën niet aan dergelijke hoeveelheden blootgesteld. Naar ons weten is er geen significante impact op de populatie van amfibieën gemeld, en dat terwijl de fungicide pyraclostrobin wereldwijd gebruikt wordt.”

    Bronnen:
    Door: Astrid Snoeys, 25/01/13
    Bron: The Guardian
    HLN, 29-01-2013
    http://www.hln.be/hln/nl/2661/Dieren/article/detail/1568374/2013/01/25/Pesticiden-kunnen-kikkers-binnen-het-uur-doden.dhtml

  • New research suggests pesticides are playing a significant and previously unknown role in the global decline of amphibians

    New research suggests pesticides are playing a significant and previously unknown role in the global decline of amphibians

    Widely used pesticides can kill frogs within an hour, new research has revealed, suggesting the chemicals are playing a significant and previously unknown role in the catastrophic global decline of amphibians. The scientists behind the study said it was both “astonishing” and “alarming” that common pesticides could be so toxic at the doses approved by regulatory authorities, adding to growing criticism of how pesticides are tested. “You would not think products registered on the market would have such a toxic effect,” said Carsten Brühl, at the University of Koblenz-Landau in Germany. “It is the simplest effect you can think of: you spray the amphibian with the pesticide and it is dead. That should translate into a dramatic effect on populations.” Trenton Garner, an ecologist at the Zoological Society of London, said: “This is a valuable addition to the substantial body of literature detailing how existing standards for the use of agricultural pesticides, herbicides and fertilisers are inadequate for the protection of biodiversity.”

    Widely used pesticides can kill frogs within an hour, new research has revealed, suggesting the chemicals are playing a significant and previously unknown role in the catastrophic global decline of amphibians. The scientists behind the study said it was both “astonishing” and “alarming” that common pesticides could be so toxic at the doses approved by regulatory authorities, adding to growing criticism of how pesticides are tested. “You would not think products registered on the market would have such a toxic effect,” said Carsten Brühl, at the University of Koblenz-Landau in Germany. “It is the simplest effect you can think of: you spray the amphibian with the pesticide and it is dead. That should translate into a dramatic effect on populations.” Trenton Garner, an ecologist at the Zoological Society of London, said: “This is a valuable addition to the substantial body of literature detailing how existing standards for the use of agricultural pesticides, herbicides and fertilisers are inadequate for the protection of biodiversity.”

    Amphibians are the best example of the great extinction of species currently under way, as they are the most threatened and rapidly declining vertebrate group. More than a third of all amphibians are included in the IUCN “red list” of endangered species, with loss of habitat, climate change and disease posing the biggest threats.

    Brühl had previously studied how easily frogs can absorb pesticides through their permeable skins, which they can breathe through when underwater. But pesticides are not required to be tested on amphibians, said Brühl: “We could only find one study for one pesticide that was using an exposure likely to occur on farmland.”

    His team chose widely used fungicides, herbicides and insecticides. The most striking results were for a fungicide called pyraclostrobin, sold as the product Headline by the manufacturer BASF and used on 90 different crops across the world. It killed all the common European frogs used as test animals within an hour when applied at the rate recommended on the label. Other fungicides, herbicides and insecticides also showed acute toxicity, even when applied at just 10% of the label rate, with the insecticide dimethoate, for example, killing 40% of animals within a week.

    The study, published on Thursday in Scientific Reports, concluded: “The observation of acute mortality in a vertebrate group caused by commercially available pesticides at recommended field rates is astonishing, since 50 years after the publication of Rachel Carson’s Silent Spring one would have thought that the development of refined risk-assessment procedures would make such effects virtually impossible.”

    A BASF spokesman disputed the findings: “This study was performed under laboratory ‘worst-case’ conditions. Under normal agricultural conditions amphibians are not exposed to such pesticide concentrations. According to our knowledge, no significant impact on amphibian populations has been reported despite the widespread and global use of the fungicide pyraclostrobin.”

    Brühl said the method, a single spray directly on to the frogs, sometimes at just 10% of the label rate, was a “realistic worst-case” scenario. He added that in the field, multiple sprays of a variety of pesticides was likely and that chemicals might run off into ponds where frogs lived.

    Sandra Bell, Friends of the Earth’s nature campaigner, said: “From frogs to bees, there is mounting evidence that the pesticide bombardment of our farmland is having a major impact on our precious wildlife. Strong action is urgently needed to get farmers off the chemical treadmill. “As well as banning the most toxic products, governments must set clear targets for reducing all pesticides and ensure farmers have safe and thoroughly tested alternatives.”

    Earlier this month, the world’s most widely used insecticide was for the first time officially labelled an “unacceptable” danger to bees feeding on flowering crops, by the European Food Safety Agency. The agency had previously stated that current “simplistic” regulations contained “major weaknesses”. “There is an urgency to address [the amphibian issue] as pesticides will be applied again soon because it’s spring, and that’s when we have all these migrations to ponds,” said Brühl. “We don’t have any data from the wild about dead frogs because no one is looking for them – and if you don’t look, you don’t find. But the pesticides are very widely used and so have the potential to have a significant effect on populations.”
    Source:
    The Guardian, 24 January 2013
    http://www.guardian.co.uk/environment/2013/jan/24/pesticides-kill-frogs-within-hour?CMP=twt_gu
    CITATION: Brühl, Carsten A.; Schmidt, Thomas; Pieper, Silvia; Alscher, Annika. Terrestrial pesticide exposure of amphibians: An underestimated cause of global decline? Scientific Reports. 2013. http://dx.doi.org/10.1038/srep01135
    Read more at http://news.mongabay.com/2013/0128-hance-chemicals-frogs.html?utm_source=dlvr.it&utm_medium=twitter#DxoqW8jm6e35YJIv.99

  • Henk Tennekes speaks at Hampshire Beekeepers Association Convention

    Henk Tennekes speaks at Hampshire Beekeepers Association Convention

    The HBA Convention was held, as in previous years, at Barton Peveril College, Eastleigh, near Southampton on 10th November 2012. Confronting environmental issues ‘head on’ we had speakers on systemic pesticides, Genetically Modified crops and global warming! With the recently published results of research undertaken in both France and Scotland pointing to detectable effects of sub-lethal levels of systemic insecticides on the nervous systems of pollinators, we were fortunate in having as a speaker Henk Tennekes, an independent toxicologist and one of the founders of http://www.smallbluemarble.org.uk a charity supporting independent research into systemic insecticides, who presented his findings on neonicotinoid insecticides and species decline. ‘His blunt, evidence based presentation was very stimulating and pulled no punches delivering the ‘chilling’ message that neonicotinoids, targeted at insects attacking plants also affected bees and other insects collecting pollen and nectar.’ It was shocking to discover how toxic and persistent these chemicals are and that they are water soluble and leach through soil to affect many arthropods and invertebrate species and so affect a wide range of animals, including humans, higher up ‘the food chain’. ‘Henk’s relevant and thought provoking presentation made a strong impression on all those present and whether or not we agreed with all his conclusions it certainly made one want to learn more about neonicotinoids’. His lecture is attached (The Italian Union of Beekeepers’ Associations [Unaapi – Mieliditalia] is distributing this lecture in Italian, see below. Maria Jose Pastor Rodriguez of Unaapi – Mieliditalia prepared a Spanish translation of the lecture, attached). Hampshire BKA has a Proposition before BBKA ACM recommending the notification of neonicotinoid-treated seed sowing to raise awareness and enable monitoring of effects on colony health and mortality. ’We should all take action to make the public aware of this problem’’.

    The HBA Convention was held, as in previous years, at Barton Peveril College, Eastleigh, near Southampton on 10th November 2012. Confronting environmental issues ‘head on’ we had speakers on systemic pesticides, Genetically Modified crops and global warming! With the recently published results of research undertaken in both France and Scotland pointing to detectable effects of sub-lethal levels of systemic insecticides on the nervous systems of pollinators, we were fortunate in having as a speaker Henk Tennekes, an independent toxicologist and one of the founders of http://www.smallbluemarble.org.uk a charity supporting independent research into systemic insecticides, who presented his findings on neonicotinoid insecticides and species decline. ‘His blunt, evidence based presentation was very stimulating and pulled no punches delivering the ‘chilling’ message that neonicotinoids, targeted at insects attacking plants also affected bees and other insects collecting pollen and nectar.’ It was shocking to discover how toxic and persistent these chemicals are and that they are water soluble and leach through soil to affect many arthropods and invertebrate species and so affect a wide range of animals, including humans, higher up ‘the food chain’. ‘Henk’s relevant and thought provoking presentation made a strong impression on all those present and whether or not we agreed with all his conclusions it certainly made one want to learn more about neonicotinoids’. His lecture is attached (The Italian Union of Beekeepers’ Associations [Unaapi – Mieliditalia] is distributing this lecture in Italian, see below. Maria Jose Pastor Rodriguez of Unaapi – Mieliditalia prepared a Spanish translation of the lecture, attached). Hampshire BKA has a Proposition before BBKA ACM recommending the notification of neonicotinoid-treated seed sowing to raise awareness and enable monitoring of effects on colony health and mortality. ’We should all take action to make the public aware of this problem’’.

    The Italian Union of Beekeepers’ Associations is distributing this lecture in Italian:
    http://www.mieliditalia.it/index.php/api-agricoltura-ambiente/notizie-api-e-pesticidi/81291-insetticidi-sistemici-un-disastro-in-atto
    Sources:
    http://www.hampshirebeekeepers.org.uk/news/1-latest-news/107-hampshire-beekeepers-association-convention-2012
    http://www.hampshirebeekeepers.org.uk/news

  • The contribution of increasing UV radiation and environmental contamination to the global decline of amphibian populations

    The contribution of increasing UV radiation and environmental contamination to the global decline of amphibian populations

    As part of an overall ‘biodiversity crisis’, many amphibian populations are in decline throughout the world. Numerous factors have contributed to these declines, including habitat destruction, pathogens, increasing ultraviolet (UV) radiation, introduced non-native species and contaminants. In this paper we review the contribution of increasing UV radiation and environmental contamination to the global decline of amphibian populations. Both UV radiation and environmental contaminants can affect amphibians at all life stages.

    As part of an overall ‘biodiversity crisis’, many amphibian populations are in decline throughout the world. Numerous factors have contributed to these declines, including habitat destruction, pathogens, increasing ultraviolet (UV) radiation, introduced non-native species and contaminants. In this paper we review the contribution of increasing UV radiation and environmental contamination to the global decline of amphibian populations. Both UV radiation and environmental contaminants can affect amphibians at all life stages.

    Exposure to UV radiation and to certain contaminants can kill amphibians and induce sublethal affects in embryos, larvae and adults. Moreover, UV radiation and contaminants may interact with one another synergistically. Synergistic interactions of UV radiation with contaminants can enhance the detrimental effects of the contaminant and UV radiation.
    Source:
    ANDREW R. BLAUSTEIN et al. Diversity and Distributions (2003) 9, 123–140 (attached)

  • Wind-borne agrochemicals may be an important factor in declines of the federally threatened California red-legged frog

    Wind-borne agrochemicals may be an important factor in declines of the federally threatened California red-legged frog

    The federally threatened California red-legged frog (Rana aurora draytonii) has disappeared from much of its range for unknown reasons. We mapped 237 historic locations for the species and determined their current population status. Using a geographic information system (GIS), we determined latitude, elevation, and land use attributes for all sites and analyzed the spatial pattern of declines. We then compared the observed patterns of decline to those predicted by the climate change, UV-B radiation, pesticides, and habitat alteration hypotheses for amphibian decline. Declines were not consistent with the climate change hypothesis but showed a strong positive association with elevation, percentage upwind agricultural land use, and local urbanization.

    The federally threatened California red-legged frog (Rana aurora draytonii) has disappeared from much of its range for unknown reasons. We mapped 237 historic locations for the species and determined their current population status. Using a geographic information system (GIS), we determined latitude, elevation, and land use attributes for all sites and analyzed the spatial pattern of declines. We then compared the observed patterns of decline to those predicted by the climate change, UV-B radiation, pesticides, and habitat alteration hypotheses for amphibian decline. Declines were not consistent with the climate change hypothesis but showed a strong positive association with elevation, percentage upwind agricultural land use, and local urbanization.

    These results apply to patterns of decline across the entire range of R. a. draytonii in California, as well as within geographic subregions. The elevational gradient in declines is consistent with the UV-B hypothesis, although the UV-B hypothesis also predicts a north-to-south gradient in declines, which we did not observe. The association of declines with the amount of upwind agricultural land use strongly suggests that wind-borne agrochemicals may be an important factor in declines. This association was most pronounced within the Central Valley–Sierra region, where other studies have documented both transport and deposition of pesticides to the Sierra Nevada and the presence of pesticide residues in the bodies of congeneric (Rana muscosa) and more distantly related (Hyla regilla) frog species.

    Source:
    CARLOS DAVIDSON et al. Ecological Applications, 11(2), 2001, pp. 464–479 (attached)

  • Pestizide − eine Gefahr für die biologische Vielfalt

    Pestizide − eine Gefahr für die biologische Vielfalt

    In Deutschland sind 70 Prozent der natürlichen Lebensräume bestandsgefährdet, zwei Drittel der Amphibien- und Reptilienarten als gefährdet eingestuft oder vom Aussterben bedroht, 30 Prozent der Farne und Blütenpflanzen sind bestandsgefährdet. Ebenso stehen zwei Drittel der Tier- und Pflanzenarten des Offenlandes auf den Roten Listen der bedrohten Arten. In Deutschland ist für die Erhaltung der biologischen Vielfalt insbesondere die Art und Weise der praktizierten Landwirtschaft ausschlaggebend, fast die Hälfte der Landesfläche ist Agrarfläche (Europäische Union: 43 Prozent). Die nationale Biodiversitätsstrategie trägt dieser Bedeutung Rechnung, Ziele zur Erhöhung des Anteils an Grünland oder Streuobstwiesen wurden vereinbart. Die Zusagen aber werden nicht eingehalten. Die Landwirtschaft in der Bundesrepublik muss, um einen signifikanten Beitrag zur Sicherung der Biodiversität zu leisten, im Rahmen einer Agrarwende weg von der intensiven Landwirtschaft hin zu einer nachhaltigen extensiven Landwirtschaft transformiert werden. Dies beinhaltet eine umfassende Veränderung der Art zu wirtschaften, speziell aber den Stopp des Einsatzes von chemisch-synthetischen Pestiziden.

    In Deutschland sind 70 Prozent der natürlichen Lebensräume bestandsgefährdet, zwei Drittel der Amphibien- und Reptilienarten als gefährdet eingestuft oder vom Aussterben bedroht, 30 Prozent der Farne und Blütenpflanzen sind bestandsgefährdet. Ebenso stehen zwei Drittel der Tier- und Pflanzenarten des Offenlandes auf den Roten Listen der bedrohten Arten. In Deutschland ist für die Erhaltung der biologischen Vielfalt insbesondere die Art und Weise der praktizierten Landwirtschaft ausschlaggebend, fast die Hälfte der Landesfläche ist Agrarfläche (Europäische Union: 43 Prozent). Die nationale Biodiversitätsstrategie trägt dieser Bedeutung Rechnung, Ziele zur Erhöhung des Anteils an Grünland oder Streuobstwiesen wurden vereinbart. Die Zusagen aber werden nicht eingehalten. Die Landwirtschaft in der Bundesrepublik muss, um einen signifikanten Beitrag zur Sicherung der Biodiversität zu leisten, im Rahmen einer Agrarwende weg von der intensiven Landwirtschaft hin zu einer nachhaltigen extensiven Landwirtschaft transformiert werden. Dies beinhaltet eine umfassende Veränderung der Art zu wirtschaften, speziell aber den Stopp des Einsatzes von chemisch-synthetischen Pestiziden.

    Pestizide wirken sich in vielfacher Hinsicht auf Lebensräume, Pflanzen und Tiere aus. Direkte Folgen sind tödliche Auswirkungen auf vermeintliche Schädlinge – aber auch “Kollateralschäden” an anderen Tieren und Pflanzen. Die Reduktion des Vorkommens einzelner Arten wirkt sich indirekt über die Nahrungskette auf andere Lebewesen aus und nimmt ihnen die Lebensgrundlage. Gleichzeitig schaffen Pestizide Formen der Landwirtschaft, die natürliche Lebensräume zerstören: Monokulturen, enge Fruchtfolgen oder nicht heimische Früchte zerstören das eingespielte Gleichgewicht. Es ist nicht einfach, den Einfluss von Pestiziden auf die biologische Vielfalt aus dem Bündel an Einflussfaktoren herauszufiltern. Dass dieser Einfluss groß ist, wurde in einer 2010 veröffentlichten, europaweiten Studie deutlich (Beilage): Von dreizehn untersuchten Faktoren der landwirtschaftlichen Intensivierung hatte der Gebrauch von Insektiziden und Fungiziden die schädlichsten Auswirkungen auf die Biodiversität. Die Artenvielfalt in Europa kann also nur erhalten werden, wenn die Verwendung von Spritzmitteln in großen Teilen der Landwirtschaft auf ein Minimum beschränkt wird.
    Quelle: BUND
    http://www.bund.net/themen_und_projekte/chemie/pestizide/gefahr_fuer_die_natur/

  • Pesticides are instrumental in declines of amphibians

    Pesticides are instrumental in declines of amphibians

    Several species of anuran amphibians have undergone drastic population declines in the western United States over the last 10 to 15 years. In California, the most severe declines are in the Sierra Mountains east of the Central Valley and downwind of the intensely agricultural San Joaquin Valley. In contrast, coastal and more northern populations across from the less agrarian Sacramento Valley are stable or declining less precipitously. In this article, we provide evidence that pesticides are instrumental in declines of these species.

    Several species of anuran amphibians have undergone drastic population declines in the western United States over the last 10 to 15 years. In California, the most severe declines are in the Sierra Mountains east of the Central Valley and downwind of the intensely agricultural San Joaquin Valley. In contrast, coastal and more northern populations across from the less agrarian Sacramento Valley are stable or declining less precipitously. In this article, we provide evidence that pesticides are instrumental in declines of these species.

    Using Hyla regilla as a sentinel species, we found that cholinesterase (ChE) activity in tadpoles was depressed in mountainous areas east of the Central Valley compared with sites along the coast or north of the Valley. Cholinesterase was also lower in areas where ranid population status was poor or moderate compared with areas with good ranid status. Up to
    50% of the sampled population in areas with reduced ChE had detectable organophosphorus residues, with concentrations as high as 190 ppb wet weight. In addition, up to 86% of some populations had measurable endosulfan concentrations and 40% had detectable 4,4′-dichlorodiphenyldichloroethylene, 4,4′-DDT, and 2,4′-DDT residues.

    Source:
    Sparling DW et al. Environmental Toxicology and Chemistry, Vol. 20, No. 7, pp. 1591–1595, 2001 (attached)