Scientists are growing increasingly concerned that coral, which grows abundantly in the circumtropical shallow waters near bodies of land, is evincing a paling, or bleaching effect. Though experts are still at odds over what has precipitated this event, most agree that it is a stress response to changes in habitat and water quality, including temperature variations and salination percentage, and predict a loss of 95 percent of existing coral populations.An exemplary symbiotic entity, scleractinian coral lives harmoniously with vertebrates, inver-tebrates. and plants. Corals receive nutrients in two ways: by capturing planktonic organisms with nematocyst-capped tentacles and by resource-sharing and recycling with single-celled algae called zooxanthellae. These algae live within the polyps of the coral, using photosynthesis to increase (and thereby strengthen) coral calci-fication. and providing energy for coral growth. The zooxanthellae benefit from the relationship through protection from predators and a steady supply of necessary carbon dioxide. Interestingly, it is the zooxanthellae that provide coral with its brilliant coloration.When coral loses its color, it is a sign that the single-celled algae are not able to thrive. Though not necessarily a sign of mortality, a pale, wan color indicates imminent danger and is considered a stress response. The zooxanthellate invertebrates lose their concentration of pigmentation or die altogether when stressed, turning translucent and allowing the slightly darker coral skeleton to show through the decaying tissue. Whether this response stems from anthropogenic pollutions such as overharvesting coral for the exotic travel market, overfishing coral waters, and increased water temperatures due to global warming, or from natural disturbances (storms, temperature extremes, and diseases), scientists fear for the future of the radiant corals. If zooxanthellate populations continue to decrease without recovery, their host corals will eventually follow suit, triggering a cascade of unanticipated biological events.
Scientists are growing increasingly concerned that coral, which grows abundantly in the circumtropical shallow waters near bodies of land, is evincing a paling, or bleaching effect.
coral 珊瑚，珊瑚虫
abundantly 丰富地
circum周边
tropical热带的
circumtropical 环热带分布的
body 主体
evince （经常间接地）表明，显示
pale v.使变暗淡n.围篱，范围，境界
bleach v.使变白，漂白剂
科学家对，大量生长在大陆附近的环热带浅水区域的珊瑚虫，正在变暗变白的事实越来越关心
Though experts are still at odds over what has precipitated this event, most agree that it is a stress response to changes in habitat and water quality, including temperature variations and salination percentage, and predict a loss of 95 percent of existing coral populations.
still at odds over 仍然存在分歧
precipitate 使(通常指不好的事件或形势)突然发生，加速
a stress response to 应激反应
variation 变化
salination n.盐化作用
虽然专家们对什么加速了这一事件仍存在分歧，但大多数人同意这是一种对水质和栖息地变化，包括温度变化和盐度变化，的应激反应，并且预测这将导致失去现存珊瑚数量的百分之95。
An exemplary symbiotic entity, scleractinian coral lives harmoniously with vertebrates, inver-tebrates. and plants.
exemplary 典型的，儆戒性的
symbiotic共生的
entity实体，独立存在体
scleractinian coral 硬珊瑚
vertebrates 脊椎动物(spine脊椎)
inver-tebrates 无脊椎的，无脊椎动物
硬珊瑚是一个典型的与脊椎动物、无脊椎动物和植物和谐共存的共生体。
Corals receive nutrients in two ways: by capturing planktonic organisms with nematocyst-capped tentacles and by resource-sharing and recycling with single-celled algae called zooxanthellae.
nutrient(s) 营养物
planktonic 浮游生物的
nematocyst-capped 线虫囊
tentacle 触手，触角，触须
algae 水藻，藻类
zooxanthellae虫黄藻
珊瑚们获得营养物质有两种方式：用线虫囊的触须捕获浮游生物，和与被称为虫黄藻的单细胞藻类共享资源和循环利用资源。
These algae live within the polyps of the coral, using photosynthesis to increase (and thereby strengthen) coral calci-fication. and providing energy for coral growth.
polyp 息肉，水螅体
synthesis n.合成，合成体
photosynthesis 光合作用，光能合成
calci-fication钙化
-fication表示“形成”，“.…..化”
这些藻类生活在珊瑚的息肉中，利用光合作用来增加(从而加强)珊瑚的钙化，并且为珊瑚生长提供能量。
The zooxanthellae benefit from the relationship through protection from predators and a steady supply of necessary carbon dioxide.
predator捕食者，掠夺者
dioxide二氧化物
这些虫黄藻从这种关系中受益，这种关系保护它们不受捕食者的侵害，并稳定地提供必要的二氧化碳。
Interestingly, it is the zooxanthellae that provide coral with its brilliant coloration.When coral loses its color, it is a sign that the single-celled algae are not able to thrive.
brilliant 颜色鲜明的，绚丽的
coloration n.动植物的自然色彩，自然花纹
thrive v.茁壮成长，兴盛
有趣的是，当珊瑚失去颜色时，正是虫黄藻给了珊瑚绚丽的颜色，这是单细胞藻类无法健康生长的标志。
Though not necessarily a sign of mortality, a pale, wan color indicates imminent danger and is considered a stress response.
mortality 死亡人数，死亡率
wan 苍白的，有倦容的，疲惫的
indicate 表明，暗示，指示
imminent 即将发生的，逼近的（尤指不愉快的事）
虽然不一定是死亡的标志，但珊瑚灰白，暗淡的颜色预示着迫在眉睫的危险，并被认为是一种应激反应。
The zooxanthellate invertebrates lose their concentration of pigmentation or die altogether when stressed, turning translucent and allowing the slightly darker coral skeleton to show through the decaying tissue.
pigmentation n.人或动物的天然肤色，天然颜色
altogether 完全地，全部地，总体来说
translucent 半透明的，皮肤透亮的
decay (物体)腐烂，(社会/文明)衰败，衰落
tissue (生物)组织
当受到压力时，带状无脊椎动物会失去它们的颜色浓度或完全死亡，变得半透明，使颜色稍深的珊瑚骨架透过腐烂的组织显现出来。
Whether this response stems from anthropogenic pollutions such as overharvesting coral for the exotic travel market, overfishing coral waters, and increased water temperatures due to global warming, or from natural disturbances (storms, temperature extremes, and diseases), scientists fear for the future of the radiant corals.
stem v.由……造成，来自，组织，n茎
stem from 由……造成
anthropogenic 人类活动引起的
harvest v.收割，捕猎
overharvesting 过捕捞
exotic 奇异的，异国的
overfish对鱼捕捞过度
due to 由于
disturbance n.骚乱，干扰，紊乱
radiant 辐射的，容光焕发的，光辉灿烂的
这一反应是否源于人为污染，如为外国旅游市场过度捕捞珊瑚、在珊瑚水域过度捕捞鱼类，以及由于全球变暖而导致水温升高，或是源于自然扰动(风暴、极端温度和疾病)，科学家们担心光彩夺目的珊瑚的未来。(因为生病的珊瑚是半透明的，通过反射光线和腐烂的带状无脊椎生物的颜色，而看起来有光泽)
If zooxanthellate populations continue to decrease without recovery, their host corals will eventually follow suit, triggering a cascade of unanticipated biological events.
trigger 枪的扳机，v.触发
cascade n.大量，瀑布
a cascade of 一系列的（像瀑布一样哗啦啦）
unanticipated 不曾预料到的，意想不到的
follow suit 跟着
如果虫黄藻的数量继续减少，没有恢复，它们的宿主珊瑚最终也会跟着减少，从而触发一系列意想不到的生物事件
It can be inferred from the passage that zooxanthellae are
A： able to use camouflage() to blend into their surroundings
B：dependent on carbon dioxide
C： unable to live without coral hosts
D： considered parasitical() to coral
E：unnecessarv for the continued survival of coral.`
答案是C