Amfibie: Algemeen

  • Bayerns Frösche und Kröten vom Aussterben bedroht

    Bayerns Frösche und Kröten vom Aussterben bedroht

    Die Zahlen sind alarmierend: 40 bis 60 Prozent weniger Amphibien als sonst haben Helfer des Bund Naturschutz bei der diesjährigen Krötenwanderung gezählt. Warum sind es auf einmal nur so wenige? “Es könnte für Bayerns Amphibien bereits fünf vor zwölf sein”, warnt Kai Frobel vom Bund Naturschutz in Bayern. Die Zahl der Frösche, Kröten und anderer Amphibien ist in diesem Jahr gravierend eingebrochen. In den elf bislang ausgewerteten Städten und Kreisen sind es 40 bis 60 Prozent weniger als sonst. In den Landkreisen Rosenheim und Straubing-Bogen teilweise sogar 90 Prozent.

    Festgestellt haben dies Helfer des Bund Naturschutz, die am Straßenrand Amphibien sammeln. Danach bringen sie diese sicher über die Fahrbahnen und zu ihren Laichplätzen. Vor allem im April wandern die Tiere in regnerischen Nächten zu Tümpeln, um dort ihre Eier abzulegen. Allerdings war der April zu trocken, das hat den Amphibien offenbar zugesetzt. Schaffen sie es zu den Tümpeln, finden sie dort in diesem Jahr oft kaum Wasser. Schuld daran habe der trockene Sommer 2018, sagt der Bund Naturschutz in Bayern. Nicht nur mit der Trockenheit haben die Amphibien zu kämpfen. Auch Unkraut- und Insektenvernichter, die in der Landwirtschaft und in Gärten eingesetzt werden, töten die Tiere. Der Verein fordert unter anderem, weniger Pestizide einzusetzen,

    Quelle: BR24, 23.05.19
    https://www.br.de/nachrichten/bayern/bayerns-froesche-und-kroeten-vom-aussterben-bedroht,RRDZkgi

  • Wildlife species in danger of disappearing from East Anglia

    Wildlife species in danger of disappearing from East Anglia

    Experts from Suffolk Wildlife Trust, Buglife and the RSPB have all pointed to species in danger of disappearing from East Anglia. They include stone curlew – only 202 pairs nested in the East of England last year; the shrill carder bee – common in the region 25 years ago but now found only in the Thames Gateway area; and the crested cow-wheat – a plant limited to a small number of roadside verges because grassland has disappeared to farming or construction. Indeed, habitat destruction and human disturbance are cited as the two most common reasons these species are on the brink.

    Here is a list of species that are on the brink:

    Turtle dove (Streptopelia turtur)

    Once a common sight in East Anglia, turtle doves are now rarely spotted having suffered a 91% UK population decline since 1995 – and there are fears that at this rate the bird’s’ UK extinction as a breeding species is a real possibility.

    Stone curlew (Burhinus oedicnemus)

    This summer migrant favours sandy soils for its ground nests but its habitat is dwindling and last year, possibly as few as 202 pairs of stone curlews are thought to have nested in the East of England. The majority – around 165 pairs – were in the Brecks, with a small number of birds breeding in other parts of the region, including the Suffolk Coast close to RSPB Minsmere nature reserve. This figure represents a fall of 30% from a peak of 290 breeding pairs in 2012, a “troubling trend” according experts at the RSPB.

    Norfolk Hawker (Aeshna isoceles)

    While the range of the Norfolk hawker has extended further south into Suffolk in recent decades, Buglife say the existence of the dragonfly in East Anglia remains under threat as most of the unspoilt grazing marsh systems that it relies on has been drained and gone under the plough.

    Crested cow-wheat (Melampyrum cristatum)

    Limited to small parts of West Suffolk, North Essex and a slither of Cambridgeshire, the crested cow-wheat now only exists in small numbers on roadside verges because most of its grassland habitat has gone. Another reason for its scarcity is its complex biology – this niche specialist relies on ants to disperse its seeds, which are shaped like ant eggs and prefers clay soils.

    Fen orchid (Liparis loeselii)

    Now only found in a couple reedbed fens in Norfolk and recently reinstated at one secret site in Suffolk, the extremely rare fen orchid is vulnerable because it is only found in a very limited number of locations. If a catastrophic event should occur at these spots, the chances are it would be wiped out from the region.

    Little tern (Sternula albifrons)

    Little terns are one of the UK’s rarest seabirds, and rely heavily on the east Norfolk coast, which supports around 20% of the national population. But busier beaches mean there is less space for this ground-nesting species while climate change is thought to be causing a reduction in the number of sand eels on our shores – a mainstay of the little tern’s diet.

    Adder (Vipera berus)

    At one time adders could be seen on the old heaths around Sudbury in west Suffolk but today the UK’s only venomous snake is most likely to be found on heaths and coastal areas in the east of the county. But research from the Amphibian and Reptile Groups UK (ARG UK) has found that 90% of the small populations of adders are in decline – this shy creature suffering from human disturbance.

    Hazel dormouse (Muscardinus avellanarius)

    Already under threat because of fragmented woodland and the ongoing loss of hedgerows, numbers of dormice have declined by 72% in 22 years, according to figures from the People’s Trust for Endangered Species (PTES).

    Hedgehog (Erinaceus europaeus)

    People of a certain age grew up seeing hedgehogs on a regular basis but nationally, numbers of this iconic mammal in rural areas have halved since 2000 and continue to fall with a lack of food and dangerous roads major problems.

    Wormwood moonshiner (Amara fusca)

    As the name would suggest, this exotic sounding Breckland beetle is dependant on the seeds of the Wormwood plant, which wildlife charity Buglife says is fast disappearing due to farming, afforestation and grazing habits. With a very restricted UK distribution and highly specialised habitat requirements, the nocturnal moonshiner is extremely vulnerable to change.

    Shrill carder bee (Bombus sylvarum)

    A bumblebee once very common across the region but now restricted to the Thames Gateway area due to habitat loss and climate change, the shrill carder bee has suffered from the wide scale use of herbicides in farming, which Buglife says has turned much of the landscape into a barren wilderness for this late season insect, which has gone from common to scarce in a 25-year population crash.

    Swallowtail (Papilio machaon britannicus)

    The UK’s largest butterfly, native swallowtails are now found only a few locations in the Broads. This is because this stunning creature is dependent on a single plant species – milk parsley – for reproduction. In other areas, milk parsley has been lost to building and other works as southern reaches of the Broads have become commercialised. Elsewhere in the UK, conditions are not right for milk parsley to grow.

    Toad (Bombina bombina)

    A recent study by Froglife found that the number of toads making their annual spring migration has fallen by two-thirds in 30 years. Just why there has been this drop remains unclear although pollution and a reduction in insect numbers, the toad’s main food source, are thought to be causes.

    Source: East Anglian Daily Times, 20 May 2019
    https://www.eadt.co.uk/business/threat-to-biodiversity-in-east-anglia-1-6059859

  • Top UN scientists warn humans at risk from biodiversity crisis

    Top UN scientists warn humans at risk from biodiversity crisis

    A landmark report by the United Nations’ scientific panel on biodiversity warns that humans are at dire risk unless urgent action is taken to restore the plants, animals and other natural resources they depend on to survive. The report, which was issued in Paris on Monday by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), describes a world where living and future generations of people face the threat of worsening food and water shortages, because of habitat and species loss.

    The rate at which plant and animal life are now disappearing from the earth is tens or hundreds of times faster than in the past, according to the report. More than 1 million species on earth face extinction – many within decades – because they “have insufficient habitat for long-term survival”. If biodiversity continues to decline at the current pace, there will be dire consequences for humans, who depend on nature to provide food, drinking water, clean air and energy. Yet the report’s authors found that human activity has been the main driving force behind species loss. “We are indeed threatening the potential food security, water security, human health and social fabric” Robert Watson, a British environmental scientist who chairs the IPBES, told The Associated Press. He added that the poor in less developed countries will bear the brunt of the burden.

    Source: France 24, May 6, 2019
    https://www.france24.com/en/20190506-biodiversity-major-un-report-describes-human-risk-animal-plant-species-decline

  • Een schimmelziekte roeit amfibieën uit

    Een schimmelziekte roeit amfibieën uit

    Het is te wijten aan de dodelijke schimmelziekte chytridiomycose. De ziekte vreet op de huid van amfibieën, waaronder kikkers, padden en salamanders. Voor het eerst hebben onderzoekers nu de wereldwijde impact van de schimmel in een nieuwe studie in kaart gebracht. En het is geen goed nieuws.

    Chytridiomycose wordt veroorzaakt door een kleine, gistachtige schimmel Batrachochytrium dendrobatidis. Deze werd voor het eerst ontdekt in 1998 en vormt een grote bedreiging voor vele soorten amfibieën. De ziekte tast de bovenste huidlagen aan van volwassen dieren en komt ook voor rond de bek van kikkervisjes. De schimmel veroorzaakt de ziekte door het verspreiden van een gifstof die immuunreacties van de amfibieën verstoort.

    Uit de bevindingen blijkt dat de schimmelziekte eigenhandig een dramatische achteruitgang teweeg heeft gebracht bij 500 verschillende soorten amfibieën. Zo zijn de aantallen met grote sprongen teruggelopen. Bij 90 soorten was het zelfs einde verhaal; zij zijn volledig van onze aardbol verdwenen. “Zeer kwaadaardige natuurziekten, waaronder chytridiomycose, dragen bij aan de zesde massa-extinctie op aarde,” constateert onderzoeker Ben Scheele.

    In de studie raadpleegden de onderzoekers gegevens uit verschillende bronnen, waaronder papers van experts op het gebied van amfibieën en de Rode Lijst van bedreigde diersoorten. Meer dan veertig onderzoekers van over de hele wereld werkten aan de studie mee om een zo globaal mogelijk beeld te scheppen. En de onderzoekers komen met schrikbarende bevindingen.

    Zo ontdekten ze dat chytridiomycose aanwezig is in meer dan 60 landen. De grootste verliezen werden genoteerd in Australië, Midden-Amerika en Zuid-Amerika. Zo blijkt bijvoorbeeld dat in de laatste dertig jaar, veertig soorten Australische kikkers in aantallen achteruit gingen. Zeven soorten stierven volledig uit. “We zijn een aantal echt bijzondere soorten kwijtgeraakt,” zegt Scheele. “Door te weten welke soorten gevaar lopen kan helpen om beschermingsmaatregelen op te stellen die voorkomen dat er meer soorten uitsterven.”

    Bron: Scientias

    Schimmelziekte roeit eigenhandig 90 soorten amfibieën uit

  • Als niets wordt ondernomen tegen bestrijdingsmiddelen, verdwijnen insecten binnen een eeuw van de planeet

    Als niets wordt ondernomen tegen bestrijdingsmiddelen, verdwijnen insecten binnen een eeuw van de planeet

    De globale insectenpopulatie is op weg richting een totale uitroeiing als de trend van de afgelopen dertig jaar zich voortzet. Binnen enkele decennia dreigt er geen enkel insect meer te zijn op onze planeet. De gevolgen zullen catastrofaal zijn voor de “natuurlijke ecosystemen”, maar ook voor “de overlevingskansen van de mensheid”. Dat stellen twee wetenschappers, onder wie een Belg, in de eerste wereldwijde studie over het onderwerp.

    Voor het eerst is er een analyse gemaakt van de wereldwijde studies over de insectensterfte wereldwijd. De Belgische onderzoeker Kris Wyckhuys, verbonden aan de Chinese academie van agriculturele wetenschappen in Beijing, en Francisco Sánchez-Bayo (universiteit van Sydney) zetten zich samen aan de grootschalige onderneming. Hun conclusies zijn allesbehalve rooskleurig. Wat heet: beide heren trekken aan de alarmbel.

    Op verschillende plekken in de wereld werd de massale insectensterfte al aangetoond, maar een globaal overzicht brengt de schaal van het probleem pas echt in kaart: maar liefst 41 procent van alle insectensoorten neemt af, terwijl ruim een derde dreigt uit te sterven. De afgelopen 25 tot 30 jaar nam de globale insectenpopulatie jaarlijks met 2,5 procent af. “Dat is zeer onrustwekkend, het is zeer snel”, zegt Bayo tegen The Guardian. “Op dit tempo zijn er binnen 10 jaar een kwart minder insecten, binnen 50 jaar is de helft nog over en na 100 jaar is er geen insect meer over.”

    Bron: Nieuwsblad, 11-02-19
    https://www.nieuwsblad.be/cnt/dmf20190211_04168519

  • The drivers of worldwide insect decline

    The drivers of worldwide insect decline

    Pesticide use is driving an “alarming” decline in the world’s insects that could have a “catastrophic” impact on nature’s ecosystems, researchers have warned. More than 40 per cent of insect species are at risk of extinction with decades, with climate change and pollution also to blame, according to a global scientific review. Their numbers are plummeting so precipitously that almost all insects could vanish within a century, the study found.

    An overhaul of the agricultural industry is “urgently needed” to “allow the recovery of declining insect populations and safeguard the vital ecosystem services they provide,” wrote co-authors from Sydney and Queensland universities. The biologists conducted a systematic review of 73 historic reports of insect declines across the world.

    Ten per cent of known insect species have already become extinct, compared to one per cent of vertebrates, they found. Of the insects that remain, 41 per cent are in decline. Over the past 30 years, the total mass of all insects dropped an average of 2.5 per cent annually. The “dramatic” fall suggest none will be left in 100 years, warned Francisco Sanchez-Bayo, of the University of Sydney’s School of Life and Environmental Sciences. “The rate of decline is really huge,” he told BBC Radio 4’s Today.

    Butterflies and moths are among the worst affected, along with bees and dung beetles. Researchers said “a considerable proportion” of aquatic fly species had also been lost already. The review highlighted four key drivers of extinction: habitat loss caused by agriculture, urbanisation and deforestation; pollution; biological factors such as invasive species and diseases; and climate change.

    Agriculture was the “main culprit” in 40 per cent of the studies reviewed, with researchers highlighting “the way we apply pesticides” as a particular threat. “We have been doing agriculture for thousands of years and we have never seen these declines,” said Dr Sanchez-Bayo. “The introduction of systemic insecticides has been in a big change in the way we do agriculture these days.”

    The review, published in the journal Biological Conservation, said: “Unless we change our ways of producing food, insects as a whole will go down the path of extinction in a few decades. “The repercussions this will have for the planet’s ecosystems are catastrophic to say the least.”

    Researchers added dwindling insect populations were further evidence of a sixth mass extinction underway among animal and plant species worldwide. A study published by researchers at Aarhus and Gothenbury universities last year warned mankind was killing off species so rapidly that evolution was unable to fill in the gaps.

    Abstract of the Review:
    Biodiversity of insects is threatened worldwide. Here, we present a comprehensive review of 73 historical reports of insect declines from across the globe, and systematically assess the underlying drivers. Our work reveals dramatic rates of decline that may lead to the extinction of 40% of the world’s insect species over the next few decades. In terrestrial ecosystems, Lepidoptera, Hymenoptera and dung beetles (Coleoptera) appear to be the taxa most affected, whereas four major aquatic taxa (Odonata, Plecoptera, Trichoptera and Ephemeroptera) have already lost a considerable proportion of species. Affected insect groups not only include specialists that occupy particular ecological niches, but also many common and generalist species. Concurrently, the abundance of a small number of species is increasing; these are all adaptable, generalist species that are occupying the vacant niches left by the ones declining. Among aquatic insects, habitat and dietary generalists, and pollutant-tolerant species are replacing the large biodiversity losses experienced in waters within agricultural and urban settings. The main drivers of species declines appear to be in order of importance: i) habitat loss and conversion to intensive agriculture and urbanisation; ii) pollution, mainly that by synthetic pesticides and fertilisers; iii) biological factors, including pathogens and introduced species; and iv) climate change. The latter factor is particularly important in tropical regions, but only affects a minority of species in colder climes and mountain settings of temperate zones. A rethinking of current agricultural practices, in particular a serious reduction in pesticide usage and its substitution with more sustainable, ecologically-based practices, is urgently needed to slow or reverse current trends, allow the recovery of declining insect populations and safeguard the vital ecosystem services they provide. In addition, effective remediation technologies should be applied to clean polluted waters in both agricultural and urban environments.

    Sources:
    The (Irish) Independent, 11 Feb 2019
    https://www.independent.ie/business/farming/forestry-enviro/environment/catastrophic-threat-to-worlds-ecosystems-as-farm-pesticides-driving-insect-extinction-37807155.html
    https://www.independent.co.uk/news/science/insect-extinction-nature-climate-change-francisco-sanchez-bayo-sydney-science-a8773326.html

    Francisco Sánchez-Bayo & Kris A.G. Wyckhuys. Biological Conservation 232 (2019) 8–27

  • We’re Edging Toward Biological Annihilation

    We’re Edging Toward Biological Annihilation

    When American entomologist Bradford Lister first visited El Yunque National Forest in Puerto Rico in 1976, little did he know that a long-term study he was about to embark on would, 40 years later, reveal a “hyperalarming” new reality. In those decades, populations of arthropods, including insects and creepy crawlies like spiders and centipedes, had plunged by an almost unimaginable 98% in El Yunque, the only tropical rainforest within the US National Forest System. Unsurprisingly, insectivores (populations of animals that feed on insects), including birds, lizards, and toads, had experienced similarly dramatic plunges, with some species vanishing entirely from that rainforest.

    If anything, the 148-page Living Planet Report published this October by the World Wildlife Fund International and the Zoological Society of London only intensified the sense of urgency in their paper. As a comprehensive survey of the health of our planet and the impact of human activity on other species, its key message was grim indeed: between 1970 and 2014, it found, monitored populations of vertebrates had declined in abundance by an average of 60% globally, with particularly pronounced losses in the tropics and in freshwater systems. South and Central America suffered a dramatic loss of 89% of such vertebrates, while freshwater populations of vertebrates declined by a lesser but still staggering 83% worldwide. The results were based on 16,704 populations of 4,005 vertebrate species, which meant that the study was not claiming a comprehensive census of all vertebrate populations. It should instead be treated as a barometer of trends in monitored populations of them.

    Source: Truthaut, 28 December 2018

    From Insects to Starfish, We’re Edging Toward Biological Annihilation

  • Pestizide sind Hauptursache des Insektensterbens

    Pestizide sind Hauptursache des Insektensterbens

    Auf Einladung des Bund für Umwelt und Naturschutz Deutschland (BUND) referierte der Insektenforscher Thomas Hörren vom Entomologischen Verein Krefeld (EVK) im Möllner Quellenhof vor 90 Besuchern über deren bahnbrechende Studie zum Thema “Rückgang der Insekten-Biodiversität”. An zahlreichen Standorten ausschließlich in Schutzgebieten hatte der EVK 27 Jahre lang die Insektenfauna untersucht. Aufgrund des enormer Datenbestand und der wissenschaftlichen Methodik waren die Entomologen in der Lage, nicht nur den schleichenden Verlust an Arten, sondern auch an Insekten-Biomasse zu dokumentieren. Danach hat die Insektenbiomasse im Zeitraum von 1990 bis 2017 im Jahresmittel um über 75 Prozent abgenommen, in den Sommermonaten sogar um über 85 Prozent. Da die Forscher keinen Zugang auf die landwirtschaftlich konventionell genutzten Flächen hatten, wird zukünftig wissenschaftlich zu prüfen sein, ob der überwältigend große Ursachenkomplex „unknown“ damit im Zusammenhang steht, was erwartet wird.

    Zum Einfluss der konventionellen Landwirtschaft berichtete Thomas Hörren über Vergleichsuntersuchungen aus dem Jahr 2013 in England, die belegen, dass in weiträumig nicht landwirtschaftlich genutzten Gebieten die Artenzahl und Biomasse der Insekten konstant waren, in landwirtschaftlich konventionell genutzten Gebieten dagegen stark abfallend waren wie in Deutschland. Hörren resümierte, dass ausgebrachte Pestizide in unserer Kulturlandschaft, auf Garten- und Landwirtschaftsflächen, Bahngleisen, in Gewerbe- und Wohngebieten, vermutlich die Hauptursache des Insektensterbens sind. Dazu werden neue Untersuchungen angestellt.

    Quelle: LOZ News, 17. November 2018
    https://www.loz-news.de/moelln/3359-pestizide-sind-hauptursache-des-insektensterbens

  • Neonicotinoids may make young wood frogs more vulnerable to predators

    Neonicotinoids may make young wood frogs more vulnerable to predators

    Neonicotinoids are widely known for their link to declining pollinator populations, but new research finds that the ill effects of these chemicals also extends to amphibian populations. In a study published late last month, scientists from the National Wildlife Research Center in Ottawa, Canada found that chronic exposure to real-world levels of the neonicotinoid imidacloprid limits the ability of juvenile wood frogs to escape a predator attack. This research adds additional evidence that neonicotinoids are harming aquatic food chains.

    Researchers investigated the impact of neonicotinoids on the post-tadpole life stage of wood frogs, which has been identified as critical to sustaining viable populations of the species. Rather than determine acute impacts that assess how lethal a pesticide is, scientists opted to observe how wood frog behavior changes as a result of chronic, real-world exposure scenarios. In particular, scientists sought to figure out whether exposure resulted in an altered behavioral response to the presence of a predator.

    As tadpoles, wood frogs were chronically exposed to real world levels of imidacloprid (1, 10, and 100 micrograms/liter), while others were left unexposed as a control. Three weeks after metamorphosis, these frogs were placed into 10 gallon tanks for observation. The tank was split into three sections, including a small pool, a gravel area, and an area with moss intended to act as shelter. A fabricated heron head and neck was used to mimic a predator attack, and researchers were able to observe the response from a viewer outside of the tank, without disturbing the frogs. Researchers observed whether the frog responded to the presence of the predator, how it responded, how quickly it moved, and whether it used shelter or refuge.

    Wood frogs exposed to imidacloprid at 10 and 100 micrograms/liter are significantly less likely to actively respond to the attack by moving in any way (such as jumping or crouching) compared to unexposed control frogs. Frogs contaminated with imidacloprid are also more likely to remain in the area of the attack. While both control and exposed frogs use refuge in a similar way, researchers concluded that these results indicate neonicotinoids may make young wood frogs more vulnerable to predators. By impacting the ability for the frogs to assess and respond to the presence of a predator, neonicotinoids may be having subtle, but important, effects on frog survival.

    Significantly, the impact of pesticides on animal behavior is not adequately studied, and often not considered by regulatory authorities. However, similar behavioral impacts are likely playing into neonicotinoid-associated declines with pollinator populations as well. In bees, these chemicals have been shown to interfere with foraging, memory, and learning.

    Source: Beyond Pesticides, 15 Nov 18

    Neonicotinoids Found to Change Frog Behavior

  • Massive reductions in arthropod abundance in Puerto Rico’s rainforest are indirectly precipitating a collapse of the forest food web

    Massive reductions in arthropod abundance in Puerto Rico’s rainforest are indirectly precipitating a collapse of the forest food web

    Arthropods, invertebrates including insects that have external skeletons, are declining at an alarming rate. While the tropics harbor the majority of arthropod species, little is known about trends in their abundance. We compared arthropod biomass in Puerto Rico’s Luquillo rainforest with data taken during the 1970s and found that biomass had fallen 10 to 60 times. Our analyses revealed synchronous declines in the lizards, frogs, and birds that eat arthropods.

    Source:
    Bradford C. Lister and Andres Garcia
    PNAS October 30, 2018 115 (44) E10397-E10406; published ahead of print October 15, 2018 https://doi.org/10.1073/pnas.1722477115