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作者：傑奇•艾倫•朱利安諾 博士
昨日，已不見，
就在日昇和日落之間，
那是兩小時的黃金時刻，
各又鑲著六十分鐘的鑽石光陰。
沒有懸賞獎金只因時光消逝永不復返。
-- 霍瑞斯•麥恩
近來的科學研究更清楚地顯示地球曾擁有各種平衡的生態系統，還有在我們理解範圍之外的無數生命。歷史上的證據明白提示著，在過去，海洋裡充滿著鯨魚、海龜、各式各樣的魚類，還有其他現在聽起來像是科幻小說裡才會出現的生命形式。
這則新訊息清楚提示了今日我們關於漁獲量和狩獵量的限額，可能是幾近毫無意義的。這些限額的根據是去估計如果沒有幾年前人類造成的生存壓力，現有的動物數目該會有多少。歷史上的證據現正說明了在人類展開掠食行為以前，那時真正的動物數量其實是現有的數倍。
這項新的研究是刊載在「科學」期刊2001年7月27日的特別發行本中。它證實了許多生態學家和考古學家已經抱持了一段時間的懷疑：沿岸的人類聚落，在過去1萬年來持續在掏空海洋資源。這樣的懷疑挑戰了我們的一般信念-我們認為在地居民對環境的衝擊較小且認為他們能和自然和諧共處。
加州「海峽群島」國家海洋禁獵區中的巨大海藻。（照片提供 美國國家海洋暨大氣總署）
這其中的事實是，一旦人類開始狩獵以後，他們的慾望就不會有滿足之時，因此生態系統開始了不平衡的模式，最後導致部分系統完全崩潰。
舉例來說，加州海岸原本水中有厚厚一層的大型海藻，並且充滿了近海魚類。掠食動物如海獺，牠們原本在加州沿岸有數十萬隻，以海膽作為食物，而海膽又以大型海藻為主食。但先是在地居民大量捕獵海獺，後又有19世紀後期歐洲人幾近滅絕式的捕殺，最後造成了海膽數目直線上升，而大型海藻也因此大量地滅亡。
這引發了破壞海岸的模式，並將加州海岸變成今日我們所見只有石頭和沙礫的荒瘠模樣。雖然今日的加州海獺存活數量未高於1,100隻，但有些人認為這數量其實太多。漁夫們經常錯將鮑魚數目的減少歸咎於海獺，而歷史記錄明白顯示了人們的大量掠食才是真正滅絕鮑魚的殺手。
過去在加勒比海有如此多的海龜，以致當時哥倫布還擔心他的船隻會因此擱淺。
當我們細查在沿岸挖掘出的堆肥或是廚餘時，就可清楚看出海洋生物因為日益增加的漁獵而減少。北美印地安人是首批居住於加勒比海附近的住民，我們從對他們廢棄堆肥的研究發現，他們遠從17世紀開始就以海龜為食。當海龜上岸產卵的時候，這種移動緩慢的動物是很容易被捕獲的。
曾經數以上千萬計的海龜，如今卻只能以千計了。
隨著時光流逝，在堆肥中出現的海龜殼持續減少，直到幾乎完全消失。很明顯地，這些築窠的群落已被滅絕殆盡。當早期的住民以及之後來自歐洲的移民從一處食物源移往另一處，且絲毫沒考慮到要為未來保留一點什麼時，一個物種接著一個物種，就這樣地都被捕獵光了。
史密斯島，位在馬里蘭州的綺沙比克灣（攝影者 瑪莉•候林傑，照片提供 美國國家海洋暨大氣總署）
在綺沙比克灣，有清楚的證據證明，這兒原本存在有充滿各種生命且互相平衡的生態系統。過去的牡蠣床曾是厚厚的一層，以致還造成行經船隻航行上的危險。但很快地，可做成美食的牡蠣都不見了；牠們在生態系統中所扮演的關鍵角色-濾淨海水，也被忽略且失去了功能，綺沙比克灣從此變成污綠一片並且不再健全。然而過去有牡蠣有效濾水的時候，海水曾是如此地澄澈明淨。
沒有了牡蠣，海灣中的化學組成也隨之改變，而對原本數量豐富的海牛、巨型鱘魚、鱷魚和鯨魚來說，這個環境也不再適宜生長了。雖然人們正在試圖復育部分的牡蠣床，但它們再也達不到過去曾有的顛峰狀態。
【文章連載】
■人類的傲慢和地球的衰微
(上) (下)
全文與圖片詳見：http://ens-news.com/ens/aug2001/2001L-08-10g.html
版權歸屬Environment News Service(ENS)，環境資訊協會(沈怡伶 譯，高文彥、蔡麗伶 審校)
中英對照全文：http://e-info.org.tw/issue/animal/2001/is-animal01100301.htm |
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By Jackie Alan Giuliano, Ph.D.
Lost, yesterday,
somewhere between sunrise and sunset,
two golden hours,each set with sixty diamond minutes.
No reward is offered for they are goneforever.
-- Horace Mann
Recent scientific studies have made it clearer than ever before that the Earth was once filled with balanced ecosystems, teeming with abundant life in numbers that are almost beyond our comprehension. Historical evidence clearly suggests that the oceans were filled with whales, sea turtles, fish, and other forms of life that seem more like a science fiction fantasy than reality.
This new information clearly suggests that today's fishing and hunting quotas may be nearly meaningless. Such quotas are based on estimates of how many animals would be present if not subjected to human pressures of but a few years ago. The historical evidence is now showing that the actual populations - before human predation began - were exponentially greater than they are today.
This new research, presented in the journal "Science" in a special July 27, 2001 issue, confirms what many ecologists and archeologists have suspected for some time - coastal human settlements have been depleting ocean resources for the last 10,000 years. This challenges the popular notion that native peoples had a small impact on the environment and lived in relative harmony with nature.
Giant kelp forest in California's Channel Islands National Marine Sanctuary (Photo courtesy National Oceanic and Atmospheric Administration
(NOAA)
The reality is that once humans began hunting, their appetite was insatiable and a pattern of imbalance started that may culminate in the complete collapse of some ecosystems.
For example, the California coastline was once thick with underwater kelp forests and teeming with nearshore fishes. Predators like the sea otter, once numbering in the hundreds of thousands along the California coast, ate sea urchins, whose major diet is kelp. Native peoples hunted the sea otters in vast numbers and Europeans in the late 1800's hunted them nearly to extinction. As a result, the urchin populations skyrocketed, decimating the kelp.
This started a destructive pattern that turned much of the California coast into the barren rocks and sand we see there today. There are fewer than 1,100 California sea otters surviving today, yet some people actually think that there are too many. Fishermen often falsely blame them for the decline in abalone numbers when historical records clearly show that human predation killed off the stocks of that animal.
There were so many sea turtles in the Caribbean that Christopher Columbus worried that his ship would run aground!
Examining the middens, or kitchen refuse piles, that have been unearthed along the coastlines, the decline in marine populations can be clearly seen as fishing pressures increased. Studies of the refuse piles of the Amerindian peoples who first settled the area around the Caribbean show that they depended heavily on sea turtles for food as long ago as the seventh century. It is easy to catch the slow moving animals when they come ashore to lay eggs.
Sea turtle populations that once measured in the tens of millions now are measured in the thousands.
But with the passage of time, the presence of turtle shells in the middens decreases until they disappear almost completely. Clearly, the nesting colonies were wiped out. Species after species were fished out as the early peoples, and later the European settlers, moved from one food source to another, without any concern for sustaining anything into the future.
Smith Island, Chesapeake Bay, Maryland (Photo by Mary Hollinger courtesy
NOAA)
In Chesapeake Bay, clear evidence exists of a once balanced ecosystem that was teeming with life. Oyster beds were so thick that they posed navigational hazards to passing ships. But the huge oysters made fine eating and they were soon gone. Their key place in the ecosystem as water filters was ignored and lost, and the Chesapeake has become murky green and unhealthy. The oysters once filtered the water so effectively that it was crystal clear.
Without the oysters, the chemical content of the bay changed and became inhospitable to the once abundant manatees, giant sturgeon, alligators, and whales. Attempts are underway to try to regrow some of those beds, but they will never reach historic levels.
http://ens-news.com/ens/aug2001/2001L-08-10g.html |
