Boerenlandvogels – WP

Amfibie: Algemeen

  • The Western Ghats have been witnessing an unusual number of frogs with deformities

    The Western Ghats have been witnessing an unusual number of frogs with deformities

    Scientists and public health experts are alarmed by the phenomenon, which they suspect to be symptomatic of underlying toxicity in the environment and the food chain. “Missing eyes, deformed hind legs, missing limbs, extra limbs, partial limbs, limbs that are bent or bony, and abnormally thin or weak limbs are some of the reported frog abnormalities in the Western ghats,” said Dr. S. Muralidharan from the Division of Ecotoxicology at Salim Ali Centre for Ornithology & Natural History.

    Since frogs are very sensitive to changes in their habitats, studying them would yield clues to the state of the environment, says Dr. Karthikeyan Vasudevan of the Centre for Cellular and Molecular Biology (CCMB), Hyderabad. “A few decades ago, the population of the bald eagle came down in the United States due to use of the DDT pesticide. We cannot commit a similar mistake. More studies are needed to fully understand the issue,” he said.

    Independent studies on the excessive use of pesticides and on the impact of pesticides on amphibians in laboratory conditions suggest a strong link between pesticide use and frog deformities.

    Dr. H.P. Gurushankara from the Central University of Kerala and Dr. S.V. Krishnamurthy from Kuvempu University, Karnataka, conducted a survey in the early 2000s and found an increased number of deformities in the frogs inhabiting paddy fields. Not only do many amphibians breed in the shallow waters of paddy fields, pesticide applications also coincide with the breeding periods of frogs.

    “Considering the scenario of global amphibian population decline, we analysed the impact of pesticides on the amphibians in laboratory conditions and concluded that pesticides could act as a major factor behind the depletion of larval and adult population,” Dr. Gurushankara said.

    The cardamom plantations of Kattapana, which reportedly use a large number of illegal pesticides, are also suspect. “These pesticides are banned in Kerala. But they are illegally brought in from Tamil Nadu,” said Dr. Muthuswamy Murugan from Kerala Agricultural University.

    “Pesticides mainly affect the reproductive health of frogs. But the deformities are only 10% of the actual problem. These chemicals ultimately reach the soil and move into the water system where the larval stage (tadpoles) of the frog develops. We are studying the causes of these deformities though ‘in vitro’ conditions, and trying to assess the environmental health of the region,” said Dr. S.D. Biju from Delhi University.

    Source: The Hindu, 11 Nov 2017
    http://www.thehindu.com/sci-tech/energy-and-environment/frogs-in-western-ghats-with-missing-eyes-extra-limbs-alarm-scientists/article20226775.ece

  • Emerging disease further jeopardizes North American frogs

    Emerging disease further jeopardizes North American frogs

    A deadly amphibian disease called severe Perkinsea infections, or SPI, is the cause of many large-scale frog die-offs in the United States, according to a new study by the U.S. Geological Survey. Frogs and salamanders are currently among the most threatened groups of animals on the planet. The two most common frog diseases, chytridiomycosis and ranavirus infection , are linked to frog population declines worldwide. The new study suggests that that SPI is the third most common infectious disease of frogs.

    Scientists with the USGS studied 247 frog die-offs in 43 states from 1999 through 2015. The researchers found that SPI caused 21 of the mass mortalities in 10 states spanning from Alaska to Florida, all involving tadpoles. Up to 95 percent of the tadpole populations died during the SPI mortality events. “Amphibians such as frogs are valuable because they serve as pest control by eating insects like mosquitos, and they are food for larger predators,” said Marcos Isidoro Ayza, a USGS scientist, University of Wisconsin-Madison post-doctoral fellow and the lead author of the study. “They’re also exceptional indicators of ecosystem health. Like the proverbial canary in a coal mine, amphibians let us know when something in our environment is going awry.”

    The SPI die-offs occurred in tadpoles of 11 frog species, including the critically endangered dusky gopherfrog in its only remaining breeding locations in Mississippi. Most of the SPI events occurred in states bordering the Atlantic Ocean and Gulf of Mexico. However, SPI was also detected in Alaska, Oregon and Minnesota.

    Source: Science Daily, Sept 19, 2017
    https://www.sciencedaily.com/releases/2017/09/170919160206.htm

  • Study examines pesticides’ impact on wood frogs

    Study examines pesticides’ impact on wood frogs

    Neonicotinoids are prophylactically used globally on a variety of crops, and there is concern for the potential impacts of neonicotinoids on aquatic ecosystems. The intensive use of pesticides on crops has been identified as a contributor to population declines of amphibians, but currently little is known regarding the sublethal effects of chronic neonicotinoid exposure on amphibians. The objective of the present study was to characterize the sublethal effect(s) of exposure to 3 environmentally relevant concentrations (1 μg/L, 10 μg/L, and 100 μg/L) of 2 neonicotinoids on larval wood frogs (Lithobates sylvaticus) using outdoor mesocosms. We exposed tadpoles to solutions of 2 commercial formulations containing imidacloprid and thiamethoxam, and assessed survival, growth, and development. Exposure to imidacloprid at 10 μg/L and 100 μg/L increased survival and delayed completion of metamorphosis compared with controls. Exposure to thiamethoxam did not influence amphibian responses. There was no significant effect of any treatment on body mass or size of the metamorphs. Further assessment of both direct and indirect effects on subtle sublethal endpoints, and the influence of multiple interacting stressors at various life stages,is needed to fully understand the effects of neonicotinoids on amphibians.

    Source: Robinson SA et al. Environ Toxicol Chem 2017, 36: 1101–1109.
    http://onlinelibrary.wiley.com/doi/10.1002/etc.3739/epdf

    Read more at: https://phys.org/news/2017-03-pesticides-impact-wood-frogs.html#jCp

  • Negative impacts of neonicotinoids in aquatic environments are a reality

    Negative impacts of neonicotinoids in aquatic environments are a reality

    Initial assessments that considered these insecticides harmless to aquatic organisms may have led to a relaxation of monitoring efforts, resulting in the worldwide contamination of many aquatic ecosystems with neonicotinoids. The decline of many populations of invertebrates, due mostly to the widespread presence of waterborne residues and the extreme chronic toxicity of neonicotinoids, is affecting the structure and function of aquatic ecosystems. Consequently, vertebrates that depend on insects and other aquatic invertebrates as their sole or main food resource are being affected. Declines of insectivore bird species are quite evident so far, but many other terrestrial and amphibian species may be at risk.

    Solutions must be found soon if we are to save the biodiversity not only of aquatic ecosystems, but all other ecosystems linked by the food web. Since the prophylactic use of seeds treated with neonicotinoids is responsible for most of the soil and aquatic contamination, while there is evidence of little productivity gain, one obvious solution is to stop the marketing of seeds coated with these insecticides and use alternative and carefully targeted methods for pest control in agriculture, such as integrated pest management (IPM). At the same time, remediation systems based on photolytic processes and wetlands phyto-remediation should be implemented to reduce as much as possible the current contamination by these and other pollutants.

    Source: Sánchez-Bayo F et al. Front. Environ. Sci., 02 November 2016 | https://doi.org/10.3389/fenvs.2016.00071
    The article has been viewed more than 5,000 times.

  • Die Liste der bedrohten Tiere und Pflanzen im Emsland ist lang

    Die Liste der bedrohten Tiere und Pflanzen im Emsland ist lang

    Kiebitze (Vanellus vanellus) gehören zu den absoluten Verlierern, sagt Jutta Over vom Nabu Emsland/Grafschaft Bentheim. Sie sind im Jahr 2017 im Emsland kaum noch zu sehen und stehen wie fast die Hälfte der 140 Brutvogelarten auf der Liste der gefährdeten Arten. Over hat für unsere Redaktion zum heutigen Tag des Artenschutzes eine Liste bedrohter Tiere und Pflanzen im Emsland erstellt. Von den 140 Brutvogelarten im Emsland seien fast die Hälfte auf der Roten Liste Niedersachsens als gefährdet eingestuft, sieben davon sogar vom Erlöschen bedroht. Hervorzuheben seien die Arten der Agrarlandschaft, wie Rebhuhn (Persix perdix), Wachtel (Coturnix coturnix) und Feldlerche (Alauda arvensis) sowie Insektenfresser, die im Winter in den Süden ziehen. Dazu gehören unter anderem die Rauch- (Hirundo rustica) und Mehlschwalben (Delichon urbicum). Akut gefährdet und mit vielen Arten auf der Roten Liste vertreten seien außerdem Rastvögel, die auf ungestörte Rastgebiete angewiesen sind. Bei den Säugetieren würden besonders die Fledermausarten den Naturschützern große Sorgen machen. Im Emsland gebe es 15 Arten, die alle gefährdet seien. „Besonders bedroht sind Arten, die an Gebäuden leben, wie die Zwergfledermaus (Pipistrellus pipistrellus) und Breitflügelfledermaus (Eptesicus serotinus)“, sagt Over. Das liege an vielen Gebäudesanierungen. Zwar dürften ihre Quartiere nur mit Ausnahmegenehmigung beseitigt werden, da die Arten streng geschützt sind, dennoch passiere dies häufig durch Unwissenheit oder Unachtsamkeit. Die in Wäldern lebenden Arten seien durch verstärkte Einschläge in Altholzbeständen bedroht.

    Rückläufig sei auch das Vorkommen der Reptilien und Amphibien. Durch Verfüllung von Feuchtgebieten und Straßenbau werde den Tieren die Lebensgrundlage entzogen. Negativ würden sich auch der Einsatz von Pflanzenschutzmitteln und Einflüsse des Tourismus auswirken. Zu den gefährdeten Arten im Emsland zählen zum Beispiel Bergmolch (Ichthyosaura alpestris, Syn.: Triturus alpestris), Ringelnatter (Natrix natrix) und Kreuzotter (Vipera berus).

    Bei den Insekten fehle den Naturschützern ein Überblick, sagt Over. „Zahlreiche Libellenarten dürften dazugehören“, führt sie aus. Außerdem würden viele gefährdete Käfer in Altholzbeständen leben. Gefährdete Muschelarten wie die Malermuschel seien in Ems und Hase zu finden.

    Während die Liste der Tiere unvollständig sei, gebe es bei den Pflanzen einen guten Überblick: Der Verbreitungsatlas der Farn- und Blütenpflanzen in Niedersachsen und Bremen weise gefährdete Pflanzenarten aus, 291 Arten aus dem Emsland stehen darauf. Sechs davon, wie das Sumpfherzblatt (Parnassia palustris) und der langblättrige Sonnentau (Drosera anglica, Syn.: Drosera longifolia), seien akut vom Aussterben bedroht. Unter den 65 stark gefährdeten Arten seien etliche Pflanzen der Moore und Feuchtgebiete zu finden. Vier Orchideenarten gehören laut Over ebenfalls zu den bedrohten Arten. Zusätzlich zur Zerstörung des Lebensraumes komme in diesem Fall das Problem des „Pflanzenklaus“ hinzu.

    Quelle: Neue Osnabrücker Zeitung, 03.03.2017
    https://www.noz.de/lokales/lingen/artikel/858606/liste-der-bedrohten-tiere-und-pflanzen-im-emsland-ist-lang

  • Infectieziektes die amfibieën op de rand van uitsterven brengen

    Infectieziektes die amfibieën op de rand van uitsterven brengen

    Wereldwijd gaat het niet goed met amfibieën en infectieziektes zijn een zeer belangrijke factor die achteruitgang en uitsterven van soorten versnellen. Twee van de bekendste amfibieziektes zijn Chytridiomycose en Ranavirus. Beide komen ook in Nederland voor en zorgen lokaal voor de achteruitgang van populaties. Er zijn echter meer ziektes waar amfibieën mee te maken hebben, waaronder Amphibiocystidium-infecties. Amfibieën die zijn geïnfecteerd met soorten uit het genus Amphibiocystidium vertonen wittige tot doorzichtige blaasjes op de huid (<1 cm). De blaasjes concentreren zich doorgaans rond de buik, maar kunnen ook op andere delen van het lichaam voorkomen en zijn variabel van vorm. Amphibiocystidium kan ook de lever infecteren en waarschijnlijk ook de nieren. Een Amphibiocystidium-infectie gaat vaak gepaard met secundaire infecties. Mogelijk faciliteert Amphibiocystidium soorten zoals Batrachochytrium dendrobatidis [Bd], die Chytridiomycosis veroorzaakt, waardoor deze een grotere impact kan hebben dan in populaties waar Amphibiocystidium weinig of niet voorkomt. Meldingen van Amphibiocystidium in Nederland zijn schaars, maar in 2013 en in 2014 zijn vondsten gedaan in Limburg en Drenthe. Tijdens een veldbezoek aan een populatie boomkikkers in Noordwolde werd een vrouwtje kleine watersalamander gevonden met symptomen van een Amphibiocystiduminfectie. Het is bekend dat de kleine watersalamander, vinpootsalamander, kamsalamander, groene kikker, bruine kikker en vroedmeesterpad getroffen kunnen worden door deze ziekte. Bij Nederlandse vissoorten zoals paling, baars, pos, drie- en tiendoornige stekelbaars, karper, snoek, brasem, vetje en blauwband zijn deze infecties ook bekend. Mogelijk kunnen ook andere inheemse soorten geïnfecteerd worden. Bron: Tariq Stark & Gaston-Denis Guex. Infecties bij amfibieën in Nederland: Amphibiocystidium. RAVON 54 | OKTOBER 2014 | JAARGANG 16 | NUMMER 3, 54-56

  • Amphibians in U.S. Declining at “Alarming and Rapid Rate”

    Amphibians in U.S. Declining at “Alarming and Rapid Rate”

    A new study finds that frogs, toads, salamanders and other amphibians in the U.S. are dying off so quickly that they could disappear from half of their habitats in the next 20 years. For some of the more endangered species, they could lose half of their habitats in as little as six years. The nine-year study, published on May 22 in PLoS One by scientists from the U.S. Geological Survey (USGS), examined population trends for 48 species at 34 sites across the country. The researchers found that on average amphibian populations were shrinking a surprising 3.7 percent per year. “Even though these declines seem small on the surface, they are not,” lead author Michael Adams, a USGS ecologist, said in a prepared release. “Small numbers build up to dramatic declines with time. We knew there was a big problem with amphibians, but these numbers are both surprising and of significant concern.”

    Worse yet, the scientists found that species currently classified as “endangered,” “vulnerable” or “near threatened” on the IUCN Red List of Threatened Species were declining much faster, at an average of 11.6 percent. Species listed as “least concern” on the Red List were declining at a slightly slower-than-average rate of just 2.7 percent.

    Source: Scientific American, May 23, 2013
    https://blogs.scientificamerican.com/extinction-countdown/amphibians-declining-alarming/

  • Virus lethal to amphibians is spreading across Portugal

    Virus lethal to amphibians is spreading across Portugal

    A new strain of ranavirus is currently causing mass mortality in several species of amphibian in the Serra da Estrela, the highest mountain range in continental Portugal. This infectious agent is hypervirulent and also affects fish and reptiles, which complicates the situation, according to a study boasting the collaboration of the National Museum of Natural Sciences in Madrid.

    An emerging virus is affecting amphibian populations in Portugal, but this is not the first time amphibians have been a source of worry in the country. In 2009, hundreds of midwife toads (Alytes obstetricans) were found dead in Serra da Estrela Natural Park.

    A research study published in the journal Scientific Reports raises a new alert on this genus of virus, which has also been discovered in Spain and elsewhere in Europe. As Jaime Bosch, a researcher at the National Museum of Natural Sciences and co-author of the study, explains: “Ranaviruses have been known about for a long time, although in recent years globalisation is setting off mass mortalities throughout the world, and new strains also keep appearing, probably from Asia.”

    The fact that these viruses also affect fish and reptiles complicates the situation enormously, firstly because they can spread easily and also because of their persistence in the environment, even after amphibians disappear.

    “They have probably been infecting amphibian populations in Spain for several decades. In 1992 we discovered what turned out to be the first known case in our country, although at the time we didn’t even know exactly which organism caused the problem,” the scientist adds.

    In autumn 2011, another curious episode of mortality arose in the Serra da Estrela, which not only affected midwife toads but also other species of amphibians in the park. The episode was in contrast to all mortality patterns previously associated with chytridiomycosis on the Iberian Peninsula and Europe.

    Tests carried out on dead animals confirmed that not only was there infection by chytrid fungi; they then discovered the new strain of ranavirus in all species analysed.

    Source: Science Daily, March 13, 2017
    https://www.sciencedaily.com/releases/2017/03/170313102410.htm

  • A fungus is attacking fire salamanders and could wreak havoc if it gets to North America

    A fungus is attacking fire salamanders and could wreak havoc if it gets to North America

    Until recently, the Bunderbos was the best place in the Netherlands to find fire salamanders. With tall broadleaf trees shading small streams, the small forest was home to thousands of the 20-centimeter-long creatures, glistening black with bright yellow spots. “It’s a very charismatic animal,” says Annemarieke Spitzen-van der Sluijs, a conservation biologist with Reptile, Amphibian & Fish Conservation Netherlands (RAVON), a nonprofit group based in Nijmegen. “It’s like a dolphin among amphibians, always smiling, with pretty eyes.”

    But starting around 2008, the population in the Bunderbos began to plummet for no apparent reason. When Frank Pasmans and An Martel, veterinarians here at Ghent University, heard about the enigmatic deaths, they recalled extinctions caused by Batrachochytrium dendrobatidis (Bd), a highly lethal fungus that infects more than 700 species of amphibian. Yet tests for Bd at their lab were negative.

    The declines became so alarming that RAVON removed 39 fire salamanders (Salamandra salamandra) from the park, safe-guarding them temporarily in an employee’s basement. When these animals began to die as well, Spitzen-van der Sluijs rushed them here, about 2 hours away, where Martel and Pasmans cultured a fungus from a salamander clinging to life. It was a new pathogen, related to Bd. They named it B. salamandrivorans (Bsal) for the ulcers that voraciously eat away at the animals’ skin.

    Source: Science Magazine, July 19, 2017
    http://www.sciencemag.org/news/2017/07/fungus-attacking-europe-s-most-beloved-salamander-it-could-wreak-havoc-if-it-gets-north

  • Researcher touts potential of frogs, toads in restoring native fisheries

    Researcher touts potential of frogs, toads in restoring native fisheries

    Frogs, toads and salamanders often fall through the cracks of scientific study, but according to recently published research from Montana State University, they play a role so important they should be incorporated into strategies for conserving freshwater fisheries. In his first peer-reviewed paper as sole author, Niall Clancy, 22, said that native fish populations continue to decline around the world despite advances in management practices. Therefore, fisheries managers might want to add new approaches to the old. Clancy is a 2017 graduate from the Department of Ecology in MSU’s College of Letters and Science. His paper, “Can Amphibians Help Conserve Native Fishes?” was published in Fisheries, a monthly journal of the American Fisheries Society, the oldest and largest professional society representing fisheries scientists.

    “A complementary suite of techniques and approaches is needed if management is to prevent further losses,” Clancy said. “One such complementary approach is the preservation of organisms that maintain ecosystem processes and functions.” Amphibians — those cold blooded creatures that need both land and water to complete their lifecycles — are such organisms, Clancy said.

    Wildlife biologists tend to overlook amphibians because they aren’t fully terrestrial, Clancy said. Fisheries experts do the same because amphibians aren’t fully aquatic. But in many flowing and standing waters, young frogs, toads and salamanders are the dominant vertebrates. They change water chemistry, redistribute nutrients and alter the habitat for fish and other aquatic organisms.

    Clancy noted the amphibians in his study can be both predator and prey. Bullfrogs eat young fish and fish eggs, for example. Fish eat tadpoles. Salamanders tend to be carnivores, while tadpoles are generally herbivores. Both affect their environment, but in different ways. The actions of freshwater fisheries managers would be most effective where amphibian populations abound, Clancy said. To preserve or boost those populations, he suggested that managers remove invasive fish from lakes and streams and stop stocking hatchery fish in lakes that don’t normally contain fish. Additionally, they could record the types and numbers of amphibians they encounter while conducting fieldwork.

    When land is involved, fisheries managers might take on an advisory role, Clancy said. They could suggest limiting human activity where amphibians live in large numbers. They might encourage riparian buffer zones, the reduction of pesticide application near water, and maintaining or improving microhabitats that are important to amphibians. Among those microhabitats are rotting logs, leaves, dense tree stands and wetlands.

    “Fisheries management plans that incorporate amphibians will likely be beneficial for much of the aquatic community,” Clancy said. His paper focused on two categories of amphibians — one being toads and frogs and the other being salamanders. A third group, called Caecilians, is not found in North America, Clancy said. Caecilians are wormlike amphibians that live mostly underground in the wet tropical regions of South and Central America, Africa and southern Asia.

    Source: Sidney Herald, Sept 26, 2017
    http://www.sidneyherald.com/news/researcher-touts-potential-of-frogs-toads-in-restoring-native-fisheries/article_01c5af94-a304-11e7-9fc1-7bdfcbe9ac46.html