首页
登录
职称英语
[img]2012q2/ct_eyyjscz2008b_eyyjscreadb_0021_20121[/img] When was the last t
[img]2012q2/ct_eyyjscz2008b_eyyjscreadb_0021_20121[/img] When was the last t
游客
2023-10-19
24
管理
问题
When was the last time you saw a frog? Chances are, if you live in a city, you have not seen one for some time. Even in wet areas once teeming with frogs and toads, it is becoming less and less easy to find those slimy, hopping and sometimes poisonous members of the animal kingdom. All over the world, even in remote jungles on the far side of the globe, frogs are losing the ecological battle for survival, and biologists are at a loss to explain their demise. Are amphibians
simply over-sensitive to changes in the ecosystem? Could their rapid decline in numbers be signalling some coming environmental disaster for us all?
This frightening scenario is in part the consequence of a dramatic increase over the last quarter of a century in the development of once natural areas of wet marshland; home not only to frogs but to all manner of wildlife. Yet, there are no obvious reasons why certain frog species are disappearing from rainforests in the Southern Hemisphere which are barely touched by human hands. The mystery is unsettling to say the least, for it is known that amphibian species are extremely sensitive to environmental variations in temperature and moisture levels. The danger is that planet Earth might not only lose a vital link in the ecological food chain (frogs keep populations of otherwise pestilent insects at manageable levels) , but we might be increasing our output of air pollutants to levels that may have already become irreversible. Frogs could be inadvertently warning us of a catastrophe.
An example of a bizarre occurrence regarding a species of frog dates from the summer of 1995 , when "an explosion” of multi-coloured frogs of the species Rana klepton esculenta occurred in the Netherlands. Normally these frogs are brown and greenish-brown, but some unknown contributory factor is turning these frogs yellow and / or orange. Nonetheless, so far, the unusual bi- and even tri-coloured frogs are functioning similarly to their normal-skinned contemporaries. It is thought that frogs with lighter coloured skins might be more likely to survive in an increasingly warm climate due to global warming.
One theory put forward to explain extinct amphibian species that seems to fit the facts concerns the depletion of the ozone layer, a well-documented phenomenon which has led to a sharp increase in ultraviolet radiation levels. The ozone layer is meant to shield the Earth from UV rays, but increased radiation may be having a greater effect upon frog populations than previously believed. Another theory is that worldwide temperature increases are upsetting the breeding cycles of frogs. [br] Attempts are being made to halt the development of wet marshland.
选项
答案
NG
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3110635.html
相关试题推荐
[img]2012q2/ct_eyyjsdz2005a_eyyjsdreadc_0863_20121[/img]Enyawasbornin19
[img]2012q2/ct_eyyjsdz2005a_eyyjsdreadc_0863_20121[/img]Enyawasbornin19
[img]2012q2/ct_eyyjsdz2005a_eyyjsdreadc_0863_20121[/img]Enyawasbornin19
[img]2012q2/ct_eyyjsdz2005a_eyyjsdreadc_0863_20121[/img]Enyawasbornin19
[img]2012q2/ct_eyyjsdz2005a_eyyjsdreadc_0863_20121[/img]Enyawasbornin19
[img]2012q2/ct_eyyjsdz2005a_eyyjsdreadc_0863_20121[/img]Enyawasbornin19
[img]2012q2/ct_eyyjsdz2005a_eyyjsdreadc_0863_20121[/img]Enyawasbornin19
[img]2012q2/ct_eyyjsdz2005b_eyyjsdreadc_0941_20121[/img][br]Thejeanshaveaz
[img]2012q2/ct_eyyjsdz2005b_eyyjsdreadc_0941_20121[/img][br]Itischeapertop
[img]2012q2/ct_eyyjsdz2005b_eyyjsdreadc_0941_20121[/img][br]Thesoleoftheme
随机试题
THEPARTYGENEStevenBennerjo
Marlowe’sbestworksincludethefollowingEXCEPTA、Tamburlaine.B、TheJewofMal
WelcometovisitourcompanyandIamverygladtohavetheopportunity
分部工程按表列参与工程建设责任单位的有关人员亲自签字,以示负责。
女性,32岁。因反复双下肢皮下出血半年来诊。体查:双下肢见散在针头大小出血点,余
以下对健康检查的目的论述错误的一项是( )。A.尽早对有疾病或有身体缺陷的儿童
在首次公开发行股票的招股说明书中,发行人主要产品的销售价格或主要原材料、燃料价
关于盗窃罪,下列说法正确的是?A.鲁某窃得公司同事吴某放置于办公室柜子内尚未激活
A.0.25%~0.5%普鲁卡因 B.1%~2%利多卡因 C.1%~2%丁卡
(2019年真题)下列参数中,影响焊条电弧焊焊接线能量大小的有()A.焊接功率
最新回复
(
0
)