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相距1.3萬公里 多種生物同時存在南北極

2009年02月18日
摘譯自2009年2月16日ENS,華盛頓首府報導;陳維婷編譯;蔡麗伶、禾引審校

科學家在阿拉斯加採集樣本,並以此追蹤北極熊 圖片提供: Census of Marine Life海洋生物普查(COML)探索行動2月16日發表結果,包括灰鯨在內,至少有235種生物同時生存在相隔1萬3千公里的南北極海域。以往認為灰鯨受到數百年的獵捕後,應該僅存於北太平洋以及北美西岸。

除了灰鯨,海洋生物普查的科學家發現南北極有許多相似的鳥類、蠕蟲、甲殼類以及類似蝸牛的翼足類(pteropods)動物。目前正在進行DNA分析,確認這些在南極的物種是否與北極的完全相同。

這份報告是首次針對南極海洋生態進行廣泛調查,顯示南極大陸周圍的水域共棲息約7500種動物,其中有半數是此地獨有。

在前往南極的航行旅途中,海洋生物普查的探索家共紀錄了5500個物種,而目前估計全球海洋生物有25萬種。

這些發現都是2007-2008年國際極地年(IPY)期間一連串驚險航行所獲得的成果。一批生物學家勇敢迎向15公尺高的浪頭進出南極海域,他們的另一批同行則經常在武裝看守員保護下避開北極熊,在北極進行工作。

科學家發現南極海域因為有高速海流,形成單一的共同生物區,雖然寒冷,卻能孕育新種生物。

過去咸信南極海的生物多樣性與數目均偏低,然而海洋生物普查的研究員與合作人員在彙整了近上百萬個地點的生物資料後,卻勾勒出一幅截然不同的畫面。

這些調查地點包括10萬年來首次暴露在陽光下的海床,其上覆蓋的古老冰棚隨著近幾年全球暖化而崩解。

科學家現在也獲得冷水域生物為了逃離逐漸趨暖的海水,往南北極移動的證據。

普查行動研究人員去年證實,有幾種章魚曾經反覆往深海擴張,過去3千萬年來,每次遷徙都與南極海冰後撤的時間同步。

他們日前則做出理論推測,南極海域持續將新種生物送入世界海洋中,包括海蜘蛛、以及與蝦、蟹有親緣關係的甲殼類。科學家相信,南極海在冰層擴張時被孤立,經過演化出現新物種,當冰層退去,新物種便循著與章魚遷徙同樣的路線,往北方海域擴散。

世界自然基金會澳洲分會的尼可爾(Rob Nicoll)16日表示,「這項研究顯示南極是極區生物的搖籃,特別是章魚、海蜘蛛與其他特殊深海動物的演化花園。」

尼可爾指出,兩極海域「為一些意外到達該處的物種提供有效的安全庇護」,而且具有「適當的隔離與廣泛的棲地種類,成為推動演化前進的引擎。」

威脅南極海洋生物多樣性的因素中,氣候變化佔了首位,此外還有外來種入侵、油污、與各種污染,包括貨船,以及公然挑戰國際法規,非法卻不受取締監管的漁船活動。

尼可爾呼籲,「我們迫切需要海洋保護區網絡,做為極區海域保育措施的骨幹架構。上一次南極洋海洋生物保育委員會(CCAAMLR)會議中,討論在南極海設立有效、大範圍的保護區,各國政府卻互扯後腿。隨著國際極地年接近尾聲,我們需要的是實際行動而不是空談。」

Marine Life Explorers Find Same Species at Both Poles
WASHINGTON, DC, February 16, 2009 (ENS) -

Gray whales are one of at least 235 species that live in both polar seas despite a distance of more than 13,000 kilometers (8,000 miles) between them, Census of Marine Life explorers said today. After centuries of whaling, these whales had been thought to remain only in the North Pacific and along the west coast of North America.

In addition to the gray whales, Census of Marine Life scientists found that both poles share in common many birds, worms, crustaceans, and snail-like pteropods. DNA analysis is underway to confirm whether the species at the South Pole are indeed identical with those at the North Pole.

Just completed, the first comprehensive study of underwater marine life in Antarctica shows that the waters around the southern continent are inhabited by some 7,500 species of animals, about half of them found nowhere else on Earth.

On voyages to the Arctic, Census of Marine Life explorers have documented 5,500 species. In comparison, the total number of species in the world's oceans is estimated at up to 250,000.

The discoveries are the result of a series of perilous voyages conducted during International Polar Year, 2007-2008. Biologists braved waves up to 48 feet high while getting to and from the Antarctic, while their Arctic colleagues often worked under the watchful eye of armed lookouts to protect them from polar bears.

The scientists have learned that the Antarctic seafloor is a single bioregion, united by high-speed current, and a cold incubator for new species.

Antarctic waters were previously thought to be low in species diversity and abundance, but Census of Antarctic Marine Life researchers and collaborators have sketched a different picture as they amassed biological data from nearly one million locations.

Those places include seafloors exposed to light for the first time in as long as 100,000 years when ancient ice shelf lids melted and disintegrated in recent years as the climate warms.

The scientists now have documented evidence of cold water species shifting towards both poles to escape rising ocean temperatures.

Census researchers last year established that several octopus types have repeatedly colonized the deep sea, each migration coinciding with retreating Antarctic ice over 30 million years.

Today they theorize that the Antarctic also regularly refreshes the world's oceans with new varieties of sea spiders and crustaceans related to shrimp and crabs. They believe the new species evolve when expansions of ice isolate Antarctica. When the ice retreats, they radiate northward along the same pathways as the octopuses.

"Antarctica is a cradle of life for polar species," said Rob Nicoll with WWF-Australia today. "In particular, the research shows it is an evolutionary garden for octopus, sea spiders and other bizarre deep sea creatures."

The polar oceans are "effective safe havens for species that arrive by chance," said Nicholl, and they have been an "engine of evolution offering the right ingredients of isolation and a wide range of habitats," he said.

The threat of climate change comes on top of other threats to the Antarctic's marine biodiversity from invasive species, oil spills, pollution through shipping and the actions of illegal, unregulated and unreported fishing vessels that flout international rules.

"Networks of marine protected areas are urgently needed as the backbone of a conservation strategy for the Polar Oceans," Nicoll said.
"At the last meeting of the Commission for the Conservation of Antarctica Marine Living Resources governments again dragged their heels over designating meaningful large areas for protection in the Southern Ocean. With International Polar Year drawing to a close we need real action and not more rhetoric," Nicholl urged.

作者

蔡麗伶(LiLing Barricman)

In my healing journey and learning to attain the breath awareness, I become aware of the reality that all the creatures of the world are breathing the same breath. Take action, here and now. From my physical being to the every corner of this out of balance's planet.