首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
During the last decade, Val Beasley of the University of Illinois College has led a team wanting to know why the world’s amphibi
During the last decade, Val Beasley of the University of Illinois College has led a team wanting to know why the world’s amphibi
admin
2012-06-10
43
问题
During the last decade, Val Beasley of the University of Illinois College has led a team wanting to know why the world’s amphibian(两栖动物) populations have been decreasing or riddled with deformed limbs.
Evidence from his and other teams points to increasing numbers of common parasites as an important cause. However, the problems facing amphibian habitats really pose a distressing example of ecosystems out of balance because of human activity, according to Beasley, a professor of biosciences and executive director of Wildlife and Ecosystem Health. Beasley’s main collaborators, postdoctoral researcher Anna M. Schotthoefer and Rebecca A. Cole, a scientist with the National Wildlife Health Center in Madison, Wis. , say they agree.
A series of their research projects -— two published in 2003 and another that will appear as a book chapter this year — dramatically refine the data on parasitic activity and argue that physically and chemically induced changes of aquatic habitats are taking a toll.
"We have to be asking what human activities are contributing to imbalances in these ecosystems to set the stage for more severe infections, " Beasley said. "It’s becoming a serious question of how we can better manage landscapes, streams, wetlands, ponds and lakes. Frogs are among the first animals that young children see in a healthy wild place, but they are not finding them in the same numbers as in past years. "
Tadpoles (蝌蚪) of many species feed on algae converting the material into the protein, fat and other nutrients that are needed by other creatures higher in the food chain, Beasley said. Amphibians are clearly important players in ecosystem functioning, he added. "The frogs that develop from tadpoles subsequently eat up thousands of insects," he said, "The frogs themselves are also important prey for reptiles, birds and mammals."
In the study funded by Chicago Zoological Society, Beasley’s team noted that Midwest landowners hollow out their ponds so that deep water prevents the establishment of aquatic plants.
Such a practice allows for easier boating, swimming and fishing, but by eliminating aquatic plants, the habitat becomes structurally barren. Herbicide use also aggravates the problem and produces chemical changes. Plant-derived oxygen is reduced, and herbicides also may have direct toxic effects on tadpoles and other animals, Beasley said. The lack of vegetation may expose tadpoles to more parasites coming from the infected snails, because the tadpoles can’t hide or use the vegetation to brush off the parasites, Schotthoefer said.
So while the parasites seem to contribute to declines and deformation in frog populations,the challenge is to find management approaches that put balance back into amphibian ecosystems, Beasley said.
Which of the following statements might Rebecca A. Cole agree?
选项
A、Amphibian habitats are under threat of exotic species.
B、Human activities have done harm to amphibian habitats.
C、Parasites have invaded and destroyed amphibian habitats.
D、No one can explain why amphibian habitats have been destroyed.
答案
B
解析
第二段指出比斯利的观点:两栖动物栖息地面临的种种问题是因人类活动而造成生态系统失衡的一个惨痛例证。从这里可以推断出人类活动对两栖动物栖息地造成了破坏。接下来表丽贝卡·A·科尔对这种观点表示认同,可见[B]为答案。这里提到两栖动物栖息地面临的问题是由人类活动所致,并未提到外来物种,排除[A]项。根据第二段的内容可排除[C]和[D]项。
转载请注明原文地址:https://kaotiyun.com/show/NtmK777K
0
专业英语四级
相关试题推荐
DecadesafterMarilynMonroe’sdeath,therewasaburstofspeculationaboutwhatshemighthavebeendoingif(anditisavery
Atthefall2001SocialScienceHistoryAssociationconventioninChicago,theCrimeandJusticenetworksponsoredaforumont
Ifyouwantchildrentoworkhardyoumust______theirinterestsinsteadoftheirsenseofduty.
Ascientificdiscoveryisoftenmade【C1】______beforesomeoneisabletoputittouse.【C2】______,scientistsdiscoveredhow
Whichtwostateshavedeclaredstatesofemergency?
TheBritisharetheEuropeanUnion’sworstlinguistswhilethecitizensofLuxembourgarethebest,accordingtoanEUpollpubl
ThomasEdisonconsideredgeniustobe______onepercentinspirationandninety-ninepercentperspiration.
Thecountyisasubdivisionofthestateusually-butnotalways-containingtwoormoretownshipsandseveralvillages.NewYork
Thetravelers______theirjourneyafterashortbreak.
Inasurprisinginteractionatsea,hugewhalesharksfollowfishingnetsneartheislandofNewGuinea—andfishermendistribute
随机试题
在正常焊接参数内,焊条熔化速度与()成正比。
()过程是设备质量形成最重要的过程,其结果也是顾客(业主)最关心的。
下列关于资本结构理论的表述,正确的有()。
某单位因城市实施规划而搬迁,自行将原有房地产转让给市政府。此项行为适用的土地增值税政策是()。
“瘸子里挑将军”是一种()
某中学甲班学生中,所有喜欢奥数的同学也都喜欢下围棋。若以上陈述为真,再加上以下哪项,则可以合乎逻辑地推出:有些喜欢看话剧的同学不喜欢奥数?()
2018年3月.十三届全国人大一次会议根据党的十九届二中全会提出的建议,审议通过了《中华人民共和国宪法修正案》。通过本次宪法修改,党的十九大确定的重大理论观点和重大方针政策,党和国家事业发展的新成就新经验新要求被载人国家根本法。主要有()
Thesenseofsoundisoneofourmostimportantmeans(方法,手段)ofknowingwhatisgoingonaroundus.Soundhasawastedproduct,
MyfriendJaneoncefoundaweasel(鼬鼠)whenhewasveryyoung.Asshewasfondofpets,shethoughtshewouldbringhimup.
Howdoesthenewplanbenefitthestudentswhoeatalltheirmealsattheschoolcafeteria?
最新回复
(
0
)