Algemeen

A frightening disease has been ravaging amphibians across the planet. At least 350 species have been infected, two hundred of which have suffered massive population reductions or extinctions, some even occurring within the space of weeks. In 1999, a single fungal species called Batrachochytrium dendrobatidis (Bd), commonly known as the chytrid fungus, was identified as the causative agent for these rapid die-offs. This facilitated preemptive testing of rare or endangered amphibian populations for Bd, the early detection of which allowed scientists to establish captive breeding populations to stem amphibian species extinctions. Frighteningly, despite this discovery, there remain perplexing instances of rapid amphibian deaths that do not test positive for Bd. An Martel of Ghent University, in the journal PNAS, has recently reported a possible explanation for these mysterious deaths. Together with an international team of scientists, she has identified a second culprit: a new chytrid species named Batrachochytrium salamandrivorans (Bs), which can be translated to "the salamander-eating fungus."

An increasing body of scientific evidence indicates that many chemicals have biological effects at doses previously considered negligible. It is increasingly evident that more subtle deleterious effects can occur due to longer-term exposure to relatively low doses of chemicals, individually or in mixtures. New concerns have recently been raised about the impact of pesticides on non-target organisms including insects, especially bees, and amphibians. Studies suggest that low doses of neonicotinoids, a group of neurotoxic chemicals widely used in many countries as insecticides, could have sublethal effects on honey bees and bumble bees with serious consequences for wild populations of these crucially important pollinators and therefore for agriculture and the environment. It has also been suggested that detailed investigation of the effect of neonicotinoids on mammalian brain function, especially brain development, is needed to protect human health, especially that of children.

Litoria is a genus of Hylidae tree frogs native to Australia, the Bismarck Archipelago, the Solomon Islands, New Guinea, the Lesser Sunda Islands, the Moluccan Islands, and Timor. They are sometimes collectively referred to as Australasian treefrogs. In Australia, some of these species are either facing an extremely high risk of extinction, or have numbers which decreased (or will) by 80% within three generations, or may even be extinct. Examples are listed below.

Built on a fragile balance of predators and prey, Australia's various ecosystems are highly susceptible to change. When human intervention consistently alters an ecosystem, this balance can be upset, seriously threatening the biodiversity. While all species are important to an ecosystem, 'keystone' species are particularly vital. These are often top predators such as crocodiles, because of the role they play in controlling prey. The southern cassowary, however, is also a keystone species as it spreads the seeds of as many as 238 species of plants in northern Queensland. "Importantly, research clearly shows that biodiversity contributes significantly to our survival, well-being and enjoyment of life, so when we lose species at the rates that we're currently witnessing, we should be gravely concerned," says Dr Euan Ritchie an ecologist at Deakin University in Melbourne. "Losing any one species is a tragedy, but what is even more concerning is the loss of a species' ecological role following its extinction," says Euan. "If we were to lose dingoes, as an example, we also lose their ability to control pest species such as foxes and cats, and overabundant herbivores, [like] pigs, goats and kangaroos, which has widespread and often negative impacts across the whole system."

All around him, even in a place as beautiful as the Little Qualicum River estuary, his office for 30 years as a biologist for the Canadian Wildlife Service, he sees the unravelling of "the web of life." "It's happening very quickly," he says. Registered Professional Biologist Neil Dawe has written over 80 papers on birds, ecology and the environment. He received Environment Canada's Regional Citation of Excellence Award for his work in co-founding and co-chairing the Brant Wildlife Festival. He received the Outstanding Service Award from the Federation of B.C. Naturalists and the Ian McTaggart-Cowan Award of Excellence in Biology from the Association of Professional Biologists of B.C. In 2006, he retired from the Canadian Wildlife Service, Environment Canada, after 31 years of managing National Wildlife Areas and Migratory Bird Sanctuaries on Vancouver Island. He is President of the Qualicum Institute: www.qualicuminstitute.ca.

Humans are modifying the global landscape at an unprecedented scale and pace. As a result, species are declining and going extinct at an alarming rate. I examined patterns of species’ declines in three different groups in relation to a number of anthropogenic variables. I found high losses of Canadian imperiled bird, mammal, amphibian and reptile species in regions with high proportions of agricultural land cover. However, losses of imperiled species are significantly more strongly related to the proportion of the region treated with agricultural pesticides. This is consistent with the hypothesis that agricultural pesticide use, or something strongly collinear with it (perhaps intensive agriculture more generally), has contributed significantly to the decline of imperiled species.

The State of Nature, a report published in May by a coalition of environmental charities, found that more than half our wildlife species are in decline. "We are heading for Armageddon in terms of nature. We are faced with a nightmare of no nature in large parts of southern England," says Mark Cocker, author of Birds and People, a monumental new account of the role birds play in human life. "The filigree of our lives, the things that make it fantastic – silver-washed fritillaries, nightingales, dunlin, water voles chomping away at the edge of the pool – are disappearing. We are faced with the most appalling loss." Cocker's passion echoes a rollickingly fierce speech to the Welsh assembly earlier this summer by Iolo Williams, the RSPB officer turned Springwatch presenter, which is still being passed around and debated among naturalists. In it, Williams recalled his childhood by the Vyrnwy river, currently imperilled by proposals for pylons and infrastructure to service vast wind farms. The Mid Wales countryside may still appear glorious but, according to Williams, it is bereft: water voles, trout, curlew and cuckoos are gone; so, too, are insects and hay meadows (Wales has lost 99% of its hay meadows since the second world war). On the moors, alien conifers have been planted. "It's like going and looking at war graves. Every single tree is a death-knell, a nail in the coffin of that moor," said Williams. "We really are on the brink of disaster."

Under the EPBC Act more than 50 species of Australian animals have been listed as extinct, including 27 mammal species, 23 bird species, and 4 frog species. The number of known extinct Australian plants is 48. Australia’s rate of species decline continues to be among the world’s highest, and is the highest in the OECD.
The list of nationally threatened species continues to grow in Australia, with 426 animal species (including presumed extinctions) and 1,339 plant species listed as threatened under the EPBC Act. Furthermore, there is some evidence that the rates of recovery once a species has been listed as threatened, whilst it is difficult to determine in short time periods, may be particularly low. In a study conducted on 38 threatened species recovery plans across every state and territory, evidence of ongoing decline in populations was displayed in 37 per cent of cases.