英語聽力文摘501 那片珊瑚HOLD不住了！

Aah, snorkeling in the Great Barrier Reef–blue, clear water, magnificent coral, beautiful fish.

How about cloudy water and dying coral and you have to look pretty hard to spot a fish anywhere?

Nobody would want to go snorkeling in waters like you just described!

Well, we may face more problems than disappointing snorkeling vacations if we keep harming the coral reefs of the world.

Like the loss of one quarter of all marine animals and plants?

That adds more! One example of a way we’re destroying coral reefs around the world is farming near reef coastlines. In the Great Barrier Reef, far off Australia, for instance, scientists studied changes in the composition of coral over time and compared that to logs recording the local flood history. Barium, a metal rich in terrestrial soil, but usually low in seawater, began to rise soon after Europeans settled the area in 1862.

You mean that after the settlers moved in and tilled land for farming, from then on, when a nearby river flooded, it washed loose soil into the reefs?

Exactly! These sediments cloud the water, blocking out sunlight that is necessary to the corals’ growth. In fact, when sedimentation run-off is extremely bad, it can smother the coral and kill it.

Sedimentation can also introduce nutrients that lead to excess growth of green algae, which can compete with the corals for space, impeding their growth and survival.

And sedimentation is just one way we’re harming coral. If we don’t take action, marine scientists predict that the majority of the coral reefs of the world will be destroyed in just 40 years.

假想潛水于大堡礁——那片蔚藍(lán)清澈的海里，美麗的魚兒游曳在一望無際的珊瑚里。

再想象另一番景象：污濁的水域，岌岌可危的珊瑚，連魚兒的影子都看不到。

絕不會有人會在剛才你描述的海里潛水的。

要是我們不停止“迫害”地球上的珊瑚，就不只是度假不能潛水的掃興了，我們面臨的問題重重。

比如，1/4海洋動植物滅絕?

不僅如此。比如，人類在珊瑚礁海岸線開墾種地，這樣會破壞全球珊瑚的生長。科學(xué)家曾研究澳大利亞大堡礁珊瑚成分的變化，比對當(dāng)?shù)貧v史上洪災(zāi)的記錄。發(fā)現(xiàn)自1862年，歐洲人移民澳大利亞起，僅在陸地土壤中富含的金屬鋇的數(shù)量開始在海里上升。

你的意思是移民者定居后，墾地務(wù)農(nóng)，附近的漲潮將疏松的土壤沖進(jìn)了大堡礁?

沒錯!這些沉淀物使水變污濁，遮蓋了珊瑚生長必需的陽光。事實上，沉淀量很多的話，珊瑚可能會窒息而死。

此外，沉淀物還可能供給綠藻瘋長的養(yǎng)分，綠藻會和珊瑚競爭生存空間，抑制珊瑚的生長，甚至是存亡。

這僅僅是眾多人類活動破壞珊瑚其中的一種。如果我們還不采取措施，海洋科學(xué)家預(yù)計世界上大部分珊瑚礁在40年內(nèi)會滅絕。