[新聞]神秘真菌侵襲 全球蛙類大量死亡

[sanari]

一個名為「兩棲動物方舟」組織的科學家表示，全球蛙類正遭到一種名為壺菌（chytrid fungus）的神秘致死真菌侵襲，導致蛙類數量銳減，這種現象與恐龍滅絕十分類似，科學家希望全球動物園、水族館以及植物園等機構，能接手照顧瀕臨絕種的蛙類，直到科學家找出阻止這種真菌殺死蛙類的辦法。

「兩棲動物方舟」的各國科學家，2月15、16日將在美國亞特蘭大集會，討論防止全球6千多種蛙類、蠑螈等生物消失的辦法。根據科學家估計，十年來已有高達170種蛙類因受真菌侵襲或過度開發、環境污染及全球暖化等原因絕種，另外有1,900多種蛙類的生存岌岌可危。

科學家懷疑這種真菌可能來自非洲，皮膚上帶有壺菌。但這種真菌免疫的非洲爪蟾已經被運往世界各地進行進一步研究。

壺菌在蛙類身上的作用類似寄生蟲，蛙類因無法順利使用毛孔而脫水致死，從澳洲到哥斯大黎加的多種蛙類滅絕都與這種真菌有關。

日本1月份也通報蛙類死於真菌的首例，導致研究組織宣布日本蛙類進入緊急狀態。在加勒比海的多米尼克島上，被島民視為珍饈的山雞蛙則幾乎因此完全消失。

亞特蘭大動物園爬蟲學展覽負責人曼德森指出，這是一種疾病逐步侵襲所有哺乳類動物、鳥類和魚類的前例，假如人類對此漠不關心，就真是愚蠢至極。

以蛙類佔多數的兩棲動物，為全球食物鏈中的重要環節，蛙類以其他動物不會接觸的昆蟲為食，成為水生動物與陸生動物間的連結，假如沒有兩棲動物，這些昆蟲的數量將無限制地增加，威脅公共衛生與食物供應。

兩棲動物也是生技醫學的重要角色，有些物種會製造能作為人類止痛藥物的化學物質，還有一種蛙類會製造能遏制愛滋病毒的化學物質。

http://tw.news.yahoo.com/article/url...5/58/am42.html

[旅行門徒Y.A.D]

Frog Chytrid fungus

Scientists think the decline and disappearance of some frogs species in Australia and overseas may be partly due to a disease caused by a Chytrid fungus.

The fungus attacks the parts of a frog's skin that have keratin in them. Since frogs use their skin in respiration, this makes it difficult for the frog to breathe. The fungus also damages the nervous system, affecting the frog's behaviour.

A sick frog may:

have discoloured skin
be sloughing, or peeling, on the outside layers of its skin. This can vary from obvious peeling of skin (particularly on the feet), to a roughness of the frog's skin that you can barely see
sit out in the open, not protecting itself by hiding
be sluggish, and have no appetite
have its legs spread slightly away from itself, rather than keeping them tucked close to its body. In more extreme cases, the frog's body will be rigid, and its back legs will trail behind it.

Chytrid fungus is probably transferred by direct contact between frogs and tadpoles, or through exposure to infected water. The disease may not kill frogs immediately, and they can swim or hop to other areas before they die, spreading fungal spores to new ponds and streams. This means it's very important not to move frogs from one area to another.
Wet or muddy boots and tyres, fishing, camping, gardening or frog-survey equipment may also be contributing to the spread of the disease.

Help stop the spread of Chytrid fungus

Please take the following precautions if you intend visiting frog habitats in the wild, including nature ponds in parks or gardens:

Only touch frogs when absolutely necessary. Remember to use disposable gloves, sample bags and sterile equipment.
Clean and dry all equipment and wet or muddy footwear before and between visiting frog sites. This may include cleaning the tyres of your vehicle before visiting known high-risk sites where threatened frog species may live.
Never move a frog from one area to another.
Carry cleaning utensils and a disinfectant for use between sites.

More information
You'll find more details, particularly for frog researchers, managers and keepers, in the NPWS Hygiene Protocol for the Control of Disease in Frogs (PDF – 1.6MB). (http://www.nationalparks.nsw.gov.au/PDFs/hyprfrog.pdf)

What to do if you find a sick frog

Some of the symptoms of Chytrid fungal infections are described above. If you think you've found a sick frog, or if you see a frog which has died recently from no obvious cause (ie. not killed by a car), please:

1. Place the frog into a container without directly touching it.

2. If the frog is still alive, make sure the container is escape-proof and has a few small air holes and a small amount of water. Ring the Frogwatch Helpline for an opinion on whether the frog is sick or whether it is likely to survive transportation. If the frog is dead, put the container into a plastic bag and into your freezer as soon as possible.

3. Consult the NPWS Frog Hygiene Protocol (PDF– 1.6MB) or visit the James Cook University Amphibian Diseases Website for instructions on how to send frozen or live frogs by courier to a laboratory and how to be reimbursed by the NPWS for your expenses.

More information

Infection of frogs by amphibian chytrid causing the disease chytridiomycosis - key threatening process declaration
The NSW Scientific Committee has declared amphibian chytrid infection to be a 'key threatening process' in NSW. See its reasons for making this declaration.(http://www.nationalparks.nsw.gov.au/...ss+declaration)

Keratin in a frog's skin: how Chytrid fungus spreads
Find out what keratin is, and where it's found in a frog. See how Chytrid fungus attacks these parts of the frog's body.(http://www.nationalparks.nsw.gov.au/...n+a+frogs+skin)

來源http://www.nationalparks.nsw.gov.au/...Chytrid+fungus