Coral in Danger危险的珊瑚

Aah, snorkeling in the Great Barrier Reef–blue, clear water, magnificent coral, beautiful fish.
假想潜水于大堡礁——那片蔚蓝清澈的海里，美丽的鱼儿游曳在一望无际的珊瑚里。
How about cloudy water and dying coral and you have to look pretty hard to spot a fish anywhere?
再想象另一番景象：污浊的水域，岌岌可危的珊瑚，连鱼儿的影子都看不到。
Nobody would want to go snorkeling in waters like you just described!
绝不会有人会在刚才你描述的海里潜水的。
Well, we may face more problems than disappointing snorkeling vacations if we keep harming the coral reefs of the world.
要是我们不停止“迫害”地球上的珊瑚，就不只是度假不能潜水的扫兴了，我们面临的问题重重。
Like the loss of one quarter of all marine animals and plants?
比如，1/4海洋动植物灭绝？
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.
不仅如此。比如，人类在珊瑚礁海岸线开垦种地，这样会破坏全球珊瑚的生长。科学家曾研究澳大利亚大堡礁珊瑚成分的变化，比对当地历史上洪灾的记录。发现自1862年，欧洲人移民澳大利亚起，仅在陆地土壤中富含的金属钡的数量开始在海里上升。
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?
你的意思是移民者定居后，垦地务农，附近的涨潮将疏松的土壤冲进了大堡礁？
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.
没错！这些沉淀物使水变污浊，遮盖了珊瑚生长必需的阳光。事实上，沉淀量很多的话，珊瑚可能会窒息而死。
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.
此外，沉淀物还可能供给绿藻疯长的养分，绿藻会和珊瑚竞争生存空间，抑制珊瑚的生长，甚至是存亡。
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.
这仅仅是众多人类活动破坏珊瑚其中的一种。如果我们还不采取措施，海洋科学家预计世界上大部分珊瑚礁在40年内会灭绝。