首页
登录
职称英语
During the last decade, Val Beasley of the University of Illinois College ha
During the last decade, Val Beasley of the University of Illinois College ha
游客
2023-11-04
48
管理
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. [br] We can conclude from the text that
选项
A、the government is seeking a solution to the problems of amphibian habitats.
B、tadpoles can make use of aquatic plants to get rid of parasites.
C、parasites can cause great damage to frogs’ nerve center.
D、tadpoles are infected after they eat infected snails.
答案
B
解析
倒数第二段指出:水生植被的缺少还可能使蝌蚪接触到更多来自染病蜗牛的寄生虫,因为蝌蚪不能躲藏或利用植被拂去这些寄生虫。由此可推知水生植物的一个用处是帮助蝌蚪除掉寄生虫,故[B]为答案。根据末段排除[A]项。[C]项和[D]项属于过度推断。
转载请注明原文地址:https://tihaiku.com/zcyy/3157452.html
相关试题推荐
Duringthelastdecade,ValBeasleyoftheUniversityofIllinoisCollegeha
Duringthelastdecade,ValBeasleyoftheUniversityofIllinoisCollegeha
Duringthelastdecade,ValBeasleyoftheUniversityofIllinoisCollegeha
CollegesportsintheUnitedStatesareahugedeal.AlmostallmajorAmeric
CollegesportsintheUnitedStatesareahugedeal.AlmostallmajorAmeric
CollegesportsintheUnitedStatesareahugedeal.AlmostallmajorAmeric
CollegesportsintheUnitedStatesareahugedeal.AlmostallmajorAmeric
CollegesportsintheUnitedStatesareahugedeal.AlmostallmajorAmeric
CollegesportsintheUnitedStatesareahugedeal.AlmostallmajorAmeric
CollegesportsintheUnitedStatesareahugedeal.AlmostallmajorAmeric
随机试题
AgeneralelectionisheldintheU.K.every______years.A、3B、4C、5D、6C英国大选是
Thispartistotestyourabilitytodopracticalwriting.Youarerequiredtow
Passage1[originaltext]与西方国家相比,中国成立博物馆的时间要晚得多,而且在过去,中国博物馆建设发展的速度是比较慢的。
[audioFiles]2018m4s/audio_ezfj_201804_032[/audioFiles]ExamFearFormos
随参信道的传输媒质存在多径传播。()
A.牵正散 B.膈下逐瘀汤 C.镇肝熄风汤 D.补阳还五汤 E.血府逐瘀
患者男,30岁。患"化脓性扁桃体炎",医嘱青霉素皮试,护士在做青霉素皮试后约五分
调查者根据经验和对总体的了解,从总体中抽取有代表性的、典型的单位作为样本的抽样方
对选定的问题进行分析、预测和评价叫做( )A.课题论证 B.课题审查 C.
2021年5月李某正式办理了提前退休手续,距法定退休年龄还有2年,取得一次性补贴
最新回复
(
0
)