世界海岸及水域被外來物種所佔據 | 環境資訊中心
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世界海岸及水域被外來物種所佔據

2008年02月27日
摘譯自2008年2月24日ENS美國華府報導;游珮綺編譯;蔡麗伶、莫聞審校

中華大閘蟹。圖片來源:California Dept. Fish and Game根據美國自然保育協會(The Nature Conservancy)本周公佈的研究顯示,世界上84%的海岸都被外來水生物種所佔據;而且研究發現舊金山海灣是地球上最多外來物種入侵的地區,在其水域中有85個外來物種,其中66%被認為是有害的。

舊金山灣一半以上的魚類以及大部份的底棲生物都不是海灣的本土生物,而且新的外來物種還持續地被引進。

這些非本土生物的外來物種被引進新的風景區、淡水系統或海洋區域,而因為這些新的地區常常缺少自然競爭者和掠食者,使得外來物種往往會取代本土的植物和動物,進而破壞食物網,改變基本的自然環境進程。

中華大閘蟹(Chinese mitten crab,學名中華絨螯蟹)即是從1850年開始入侵三角洲和舊金山海灣的200多個外來物種之一。這些小螃蟹透過船舶壓艙水被帶到舊金山,最開始的紀錄是在1992年的加州。牠們快速的繁殖,而且擴散到整個三角洲,而因為大閘蟹會掠食幼鮭,使得整個加州的鮭魚族群可能陷於瀕臨絕種的危機。

美國自然保育協會的保育科學家,同時也是『外來物種對海洋生物多樣性造成的全球性威脅之評估』的研究報告主筆莫納(Jennifer Molnar)表示「這個問題影響非常巨大」,而此篇報告也在『生態學與環境新領域』期刊中進行發表。

莫納表示,「每天都有外來物種藏匿在成千上萬隻的船舶之中穿越海洋來到此地,也由於如此,在每次的運送中預估有多達1萬個的外來物種被引進。」

這是第一次針對海洋外來物種的衝擊和起因進行量化研究的全球性評估,而在報告中也就外來物種的棲息地、牠們如何被運送以及哪些物種對本土棲地的傷害最大進行了相關評估。

莫納也指出,「一旦外來物種在海洋中建立棲地,就幾乎不可能將牠們移除;因而對付這些外來物種最好的首要方法就是防止牠們登陸。」

此研究站在全球性的角度來分析問題,其綜合了329個水生物種的相關資訊,並從350個資料來源建立圖檔信息。

這個報告輔以地理上的參考資料以及公開可取得的海洋外來物種資料庫,使得這些資訊足以用來確定每個區域受到最大威脅的物種為何以及如何選擇防止更多傷害的優先策略。

World's Coastal Waters Riddled with Invasive Species
WASHINGTON, DC, February 24, 2008 (ENS)

Eighty-four percent of the world's coasts are being colonized by foreign aquatic species, according to a Nature Conservancy study published this week. San Francisco Bay is the most invaded aquatic region on Earth, the study finds, with 85 invasive species in its waters, 66 percent of them considered harmful.

More than half of San Francisco Bay fish and most of its bottom-dwelling organisms are not native to the Bay, and new invaders are constantly being introduced.

Invasive species are non-native species that have been introduced into a new landscape, freshwater system or ocean region. Because this new area often lacks natural competitors and predators, the invaders tend to displace native plants and animals, disrupt food webs, and alter fundamental natural environmental processes.

The Chinese mitten crab is one of more than 200 exotic species which have invaded the Delta and San Francisco Bay since the 1850s. These small crabs, which were brought to the San Francisco Bay via ships' ballast water, were first were documented in California in 1992. They reproduce rapidly and have spread throughout the Delta. They may imperil the state's threatened and endangered salmon populations due to the crabs' appetite for juvenile salmon.

"The scale of this problem is vast," said Jennifer Molnar, conservation scientist at The Nature Conservancy and lead author of the study, "Assessing the Global Threat of Invasive Species to Marine Biodiversity," published in the journal "Frontiers in Ecology and the Environment."

"Every day, thousands of vessels cross our oceans with invasive species hitchhiking on their hulls," Molnar said. "Because of this, as many as 10,000 species are estimated to be in transit at any one time."

The first quantitative global assessment of the impacts and causes of marine invasive species, the study evaluates where they are located, how they are transported, and which species are the most harmful to native habitats.

"Once alien species become established in marine habitats, it can be nearly impossible to remove them," said Molnar. "The best way to address these invaders is to prevent their arrival or introduction in the first place."

The study, analyzes the problem on a global scale by synthesizing information on 329 aquatic species, drawing information from over 350 data sources.

The report is accompanied by a geographically referenced and publicly available database of marine invaders that can be used to determine the most threatening species per region, and to prioritize strategies for preventing further damage.

全文及圖片詳見:ENS

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.