每日英語跟讀 Ep.863: Silence is golden for whales as lockdown reduces ocean noise封城降低海洋噪音

In cities, human lockdowns during the coronavirus pandemic have offered some respite to the natural world, with clear skies and the return of wildlife to waterways. Now evidence of a drop in underwater noise pollution has led experts to predict the crisis may also be good news for whales and other sea mammals.

在都市中，人類在武漢肺炎肆虐全球期間實施的封城措施，為自然世界提供了喘息的機會，天空澄澈，野生動植物也重返水路，現在更出現水下噪音汙染降低的確切證據。專家學者預測，這場危機對鯨豚和其他海洋哺乳類動物而言，或許是好事一樁。

Researchers examining real-time underwater sound signals from seabed observatories run by Ocean Networks Canada near the port of Vancouver found a significant drop in low-frequency sound associated with ships. David Barclay, assistant professor of oceanography at Dalhousie University, the co-author of a paper reviewing the phenomena, examined sound power — a way of measuring “loudness” — in the 100 Hz range from two sites, one inland and one farther offshore. He found a significant drop in noise from both.

研究人員近日檢驗溫哥華港附近、由「加拿大海洋網絡倡議」營運的海床觀測站所傳回的即時水下聲音訊號，發現和船舶相關的低頻聲響明顯降低。達爾豪斯大學的海洋學助理教授戴維．巴克萊是探討此現象的研究共同作者之一，他檢驗兩處地點所記錄到一百赫茲範圍內的「音功率」，也就是一種測量響度的方法。 一處記錄點位於內陸，另一處則是位於離岸甚遠的海中。巴克萊發現，兩處噪音的音量都大幅降低。

“Generally, we know underwater noise at this frequency has effects on marine mammals,” Barclay said. The findings of Barclay and his researchers were first published in the Narwhal. “There has been a consistent drop in noise since 1 January, which has amounted to a change of four or five decibels in the period up to 1 April,” he said. Economic data from the port showed a drop of around 20 percent in exports and imports over the same period, he said.

「一般而言，我們知道這個頻率的水下噪音會對海洋哺乳動物造成影響」，巴克萊說。他和其他研究人員的發現最初發表於新聞媒體《獨角鯨》。巴克萊指出：「水下噪音自從一月一日至今持續減少，到四月一日為止這段期間總共降低了四到五分貝。」他也提到，溫哥華港的經濟資料顯示，同一時期的進出口量大約減少了百分之二十。

The deep ocean site, around 60km from the shipping lanes and in 3,000m of water, also showed a drop in average weekly noise of 1.5 decibels, or around a 15 percent decrease in power, Barclay said. “This gives us an idea of the scale over which this reduction in noise can be observed.”

巴克萊表示，距離船舶航道約六十公里、水深三千米的深海測量點，平均每週記錄到的噪音也降低了一點五分貝，換算後功率減少百分之十五。「這提供我們一個像比例尺的概念，藉以觀察噪音的減少程度。」

The reduction in ship traffic in the ocean, which Barclay compares to a “giant human experiment,” has had scientists racing to find out the effect on marine life. “We are facing a moment of truth,” said Michelle Fournet, a marine acoustician at Cornell University, who studies humpback whales in south-east Alaska. “We have an opportunity to listen — and that opportunity to listen will not appear again in our lifetime.”

巴克萊將海洋中的船舶交通運量減少比喻為一次「超大型人類實驗」，此現象已促使許多科學家競相探索其對於海洋生物造成的影響。在阿拉斯加東南部研究座頭鯨的康乃爾大學海洋聲學家米歇爾．富內特指出：「我們眼下面對一個關鍵時刻。」她進一步解釋：「現在是傾聽海洋的大好良機，而這個機會這輩子不會再出現第二次。」

Following the Sept. 11, 2001, terrorist attacks, when ship and air traffic fell in North America, US researchers were similarly able to study whales in a quieter ocean, with a landmark study concluding that ship noise was associated with chronic stress in baleen whales. “We have a generation of humpbacks that have never known a quiet ocean,” said Fournet, whose work has shown that the whales alter their calling behavior in response to a noisy ocean.

在九一一恐怖攻擊事件發生後，北美的船舶與空中交通運量一度大幅降低，美國科學家曾經利用這個類似的機會，在比較安靜的海中研究鯨豚，最終催生出一項具有指標意義的研究，指出船舶噪音與鬚鯨的慢性壓力相關。富內特表示：「有一整個世代的座頭鯨從來不曾看過安靜的海洋。」富內特的研究曾發現座頭鯨會因應吵雜的海洋環境，改變它們呼叫的行為。

Late April usually marks the beginning of the cruise ship season in south-east Alaska, with the boats docking at Vancouver before heading north. This year the health crisis has halted them. “What we know about whales in south-east Alaska is that when it gets noisy they call less, and when boats go by they call less,” said Fournet. “I expect what we might see is an opportunity for whales to have more conversation and to have more complex conversation.”

四月下旬通常代表阿拉斯加東南部的遊輪季節正式開始，船隻在向北行駛之前會先停泊在溫哥華。今年，武漢肺炎造成的健康危機使得郵輪全數停擺。富內特表示：「關於阿拉斯加東南部的鯨魚，我們所知道的是，它們在環境嘈雜時比較少呼喚彼此，船隻經過時也是如此。」她接著指出：「我期待能看到一個讓鯨魚進行更多、更複雜對話的機會。」

Ocean scientists worldwide, many of whom are unable to carry out practical work due to the pandemic, are desperate to collect data from this once-in-a-lifetime opportunity to listen. Nathan Merchant, a bioacoustics expert at the UK government’s Centre for Environment, Fisheries and Aquaculture Science (Cefas) in Lowestoft, said: “We are on tenterhooks waiting to see what our records are saying.” Cefas has hydrophones to collect noise data on four sites: two in the North Sea, one in Plymouth and one near Bangor.

世界各地的海洋科學家迫切想要藉這個千載難逢的機會收集資料，但是其中許多人受疫情影響無法實際進行工作。英國政府機構「環境、漁業和水產養殖科學中心」的生物聲學專家納森‧墨爾強說：「我們現在如坐針氈，迫不及待想要看到紀錄顯示的結果。」科學中心目前在英國四個地點設有水中收音器，用以收集噪音資料，其中兩處位於北海，一處位於普利茅斯，另一處則靠近威爾斯的班戈市。

Merchant said there have been international efforts to coordinate the work of monitoring underwater noise. “We will be looking at how the coronavirus is affecting underwater noise throughout Europe, so this work out of Canada will be the first of many,” he said. He and his colleagues have long been discussing how they could ever conduct an experiment to make the ocean quieter, in order to find out what benefit it would have. “We have this natural experiment going on. Of course it is a terrible crisis, but we may as well get on and look at the data, to find out what effect it is having.”

墨爾強表示，目前國際間正在努力協調水下噪音的監測工作。他說：「我們將仔細觀察新冠病毒會如何影響歐洲各地的水面下噪音，因此這份加拿大研究會是眾多相關研究裡面的第一份。」長期以來，墨爾強和同事都在討論到底該如何進行實驗，才能讓海洋變得安靜一點，藉此找出可能的裨益。他表示：「現在有了這場自然界的實驗，而且仍在持續中。當然，這是一場慘烈的危機，但是我們倒不如繼續做事，觀察數據，找出它正在造成的影響。」

Source article: https://www.taipeitimes.com/News/lang/archives/2020/05/17/2003736527