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
2024-09-24
43
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] Which creature is higher in the food chain than tadpoles or frogs?
选项
A、Insects.
B、Algae.
C、Eagles.
D、Snails.
答案
C
解析
第五段最后指出:蝌蚪长成青蛙后能吃掉数干种昆虫。青蛙本身也是爬行动物、鸟类和哺乳动物的重要猎物。eagle“鹰”可以以青蛙为食,位于青蛙食物链的上端,故[C]为答案。根据第五段结尾排除[A]项。据第五段首句排除[B]项。倒数第二段提到了蜗牛,但这与第五段提到的食物链无关,排除[D]项。
转载请注明原文地址:https://tihaiku.com/zcyy/3772019.html
相关试题推荐
Thewaronsmoking,nowfivedecadesoldandcounting,isoneofthenation’
Thewaronsmoking,nowfivedecadesoldandcounting,isoneofthenation’
Iwasasecond-yearmedicalstudentattheuniversity,andwasonmysecond
Iwasasecond-yearmedicalstudentattheuniversity,andwasonmysecond
Iwasasecond-yearmedicalstudentattheuniversity,andwasonmysecond
Theseissueswerediscussedatlengthduringthemeeting.Theunderlinedpartme
Theuniversityconsistendyreceivesahigh______forthequalityofitsteaching
Duringtheeconomiccrisis,theyhadtocutbackproductionand______workers.A、l
Twoofherbrotherswere______duringtheSecondWorldWar.A、calledupB、calledo
Thesocialcompetitionisnowintense,sotheyoungpeopleincollegeshould
随机试题
WhatdoAmericanparentsexpecttheirchildrentoacquireinschool?[br]Thevi
Aftergoingoversomebasicabouthearing,theteacherwillleadthestudentsto
设 (Ⅰ)求满足Aξ2=ξ1,A2ξ3=ξ1的所有向量ξ2,ξ3;
D
电子商务发展的核心与关键问题是交易的安全性,目前安全交易中最重要的两个协议是(
室内给水管与冷冻水管、热水管共架或同沟水平敷设时,给水管应敷设在()。A:冷冻
金融互换主要包括( )。?A.利率互换 B.货币互换 C.股权互换 D.
《货币市场基金管理暂行规定》规定货币市场基金不能投资的金融工具包括( )。
根据现行规定,以下安全文明施工费的说法中,正确是( )。 A、发包人应在工程
女性,27岁,既往月经规律,停经50天,近3天晨起呕吐,厌油,伴轻度尿频,仍坚持
最新回复
(
0
)