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
2024-08-18
13
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] The decline in the numbers of frogs worldwide may be warning us of a______.
选项
答案
catastrophe
解析
(第二段最后一句提到Frogs could be inadvertently warning us of a catastrophe。)
转载请注明原文地址:https://tihaiku.com/zcyy/3725209.html
相关试题推荐
Findtheweighttobalancethescales.[img]2012q2/ct_eyyjscz2007a_eyyjsciq_0095
[img]2012q2/ct_eyyjscz2007a_eyyjscreada_0097_20121[/img]Openingnightat.t
[img]2012q2/ct_eyyjscz2007a_eyyjscreada_0097_20121[/img]Openingnightat.t
[img]2012q2/ct_eyyjscz2008b_eyyjscreadb_0021_20121[/img]Whenwasthelastt
[img]2012q2/ct_eyyjscz2008b_eyyjscreadb_0021_20121[/img]Whenwasthelastt
[img]2012q2/ct_eyyjscz2008b_eyyjscreadb_0021_20121[/img]Whenwasthelastt
[img]2012q2/ct_eyyjscz2008b_eyyjscreadb_0021_20121[/img]Whenwasthelastt
[img]2012q2/ct_eyyjscz2008b_eyyjscreadb_0021_20121[/img]Whenwasthelastt
Completethesequence.[img]2012q2/ct_eyyjscz2008a_eyyjsciq_0509_20122[/img]Q
Whichdrawingshowsthepositionofthehandle?[img]2012q2/ct_eyyjscz2008a_eyyj
随机试题
After20yearsofmarriage,ahusbandmaystillnotunderstandhiswife.How
Inthecompetitivemodel—theeconomyofmanysellerseachwithasmallshare
Thereareseveralpossiblerelationshipsbetweenlanguageandsociety.One
A、Waterispouredintotheear.B、Itisthesafestmethodofall.C、Coldwaters
一般来说,执行价格与标的物市场价格的差额(),则时间价值就();差额
基金客户服务宣传与推介工作的内容不包括()。A.对以往销售的历史数据进行收
某住宅采用墙下条形基础,建于粉质黏土地基上,未见地下水,由载荷试验确定的承载力特
1994-83.功能活血止痛、行气解郁、凉血清心、利胆退黄的药是 A.大黄B
土工织物软体排护底排体沉放过程中,当施工区水深大于()时,沉排前宜通过试验确定
确诊宫颈癌最可靠的方法是A、宫颈刮片细胞学检查 B、阴道镜检查 C、碘试验
最新回复
(
0
)