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
The Mediterranean’s Killer Algae 1. Today there are many invasive species threatening ecosystems all over the world, but few
The Mediterranean’s Killer Algae 1. Today there are many invasive species threatening ecosystems all over the world, but few
admin
2012-01-14
44
问题
The Mediterranean’s Killer Algae
1. Today there are many invasive species threatening ecosystems all over the world, but few are of as much concern as Caulerpa taxifolia.This species of green algae grows in long, thin blades similar in appearance to sea grass. Each individual alga is single-celled, with a length of up to a meter, they are some of the largest cells in the world. Algae contain chlorophyll and produce their own food through photosynthesis. Also they reproduce asexually, meaning that if an alga is cut in two each half wilt develop into a whole new organism.
2. Caulerpa taxifolia’s native habitats are the tropical waters of the Caribbean, south Pacific, east Atlantic, and Indian Ocean. However, in the 1970s, a new strain was bred in Europe to decorate exhibits in saltwater aquariums. The strain proved useful for this purpose, for it was able to grow more quickly, form denser patches, and
tolerate
a greater temperature range--from 10 to 31 degree Celsius--than the original. Created in Germany, the improved algal strain was distributed in 1980 to, among other facilities, the Oceanographic Museum in Monaco, a tiny country on the French coast. Four years later, a sample of the algae escaped the museum and began to grow on the seafloor just outside.
3. By 1989, this small sample had turned into a 2.2-acre field of Caulerpa taxifolia.A It continued to spread rapidly throughout the Mediterranean, appearing at locations up to 350 kilometers from Monaco in 1991, and by 1994 it had arrived in the waters of Italy, Croatia, and Spain.B Officials in the region, however, were slow to respond,C Their delays allowed the species to develop a strong foothold in the Mediterranean, and the invasion reached global proportions when the algae were spotted off the coasts of California in 1998 and Australia in 2000.D
4. Dubbed "killer algae" by many scientists, the aquarium strain of Caulerpa taxifolia poses a whole host of threats to the areas it colonizes. Its rapid, dense growth patterns enable it to successfully out-compete all native varieties of algae and sea grasses. Due to its ability to thrive in both warm and cold waters at a variety of depths(anywhere from one to 100 meters), few coastal marine environments are safe. The disappearance of native vegetation affects all the animals that depend on it for food and shelter, while Caulerpa taxifolia itself is inedible to most species because it
secretes
many harmful toxins.
5. The algae also cause negative repercussions for humans, in particular the commercial fishing industry. As a result of habitat loss, many species fishermen have relied on for centuries are no longer available, and the algae are notorious for clogging fishing nets and even snagging boat propellers. In addition, the decrease in the natural diversity of plant and animal life in the Mediterranean has led to a severe decline
in marine tourism
.
6. In recent years, many methods have been employed in attempts to eliminate the invasive algae. The simplest is known as manual uprooting, in which individual divers use their hands to pull the algae out by the roots. Unfortunately, Caulerpa taxifolia has spread in the Mediterranean to the point that this method is no longer
feasible
there. While it holds promise for removing small, isolated patches, extreme care must be taken, as any small fragments of the algae left behind could grow and take root once again.
7. Various physico-chemical procedures have been tried as well. These include exposure to copper and salt, air suction, ultrasound devices, and hot water jets, but each seems more effective at slowing the algae’s expansion than actually eliminating it. Studies of biological methods, such as the introduction of sea slugs* that feed on the algae, have also yielded discouraging results. Instead of consuming the algae blades, the slugs merely cut
them
into small pieces that could easily disperse and form new colonies elsewhere.
Until an answer to the problem is found, scientists urge caution, encouraging marine organizations to be on the lookout for new algae growth and to help educate the public about the serious risks this invasive species represents.
slug* a small slow-moving creature with a long soft body and no legs, like a snail without a shell.
The word tolerate in the passage is closest in meaning to
选项
A、symbolize.
B、formulate.
C、withstand.
D、intensify.
答案
C
解析
转载请注明原文地址:https://kaotiyun.com/show/MtyO777K
0
托福(TOEFL)
相关试题推荐
Youshouldspendabout20minutesonQuestions1-13,whicharebasedonReadingPassage1below.CLASSIFYINGSOCIETIESAlthough
Completethesummary.ChooseNOMORETHANTWOWORDSfromthepassageforeachanswer.Instrumentssimilartotheguitarhavebee
WhichthreeforeignlanguagesaretraditionallytaughtintheUSA?Thelecturersaysthatchildrentakemoreinterestinlearni
WhichpiechartshowstheagesoftheAsianstudentssurveyed?______ofAsianstudentsgavelowerstudyfeesasareasonfor
Thelecturersaysthatanessayislike______toaspecificquestion.【36】
Completethelecturenotes.UseNOMORETHANTHREEWORDSforeachanswer.PurposeoftheminilectureToexperience【T32】______
Completethenotesbelow.WriteONEWORDONLYforeachanswer.TheTawnyOwlMost【L31】______owlspeciesinUKStronglynocturna
ChooseTWOletters,A-EWhichTWOproblemsdoSamandthetutoridentifyconcerninggroupassignments?APersonalrelationships.
Choosethecorrectletter,A,BorC.WhatdoesJimthinkaboutthedifferenceamongspeciesinnaturalandartificiallight?
TemperatureThreescalesoftemperature,eachofwhichpermitsaprecisemeasurement,areinconcurrentuse:theFahrenheit,
随机试题
在我们的生活里,有一段时光,这时青春的________成了记忆,夏日茂盛的回音在空中还隐约可闻。这时看人生,问题不是如何发展,而是如何真正生活;不是如何奋斗操劳,而是如何享受自己拥有的那宝贵的刹那;不是如何去________精力,而是如何________那
患儿男,1岁。头发稀黄,皮肤白嫩,头不能竖起,间断抽搐。尿有鼠尿味。该患儿的诊断是
A.由县级以上卫生行政部门处以罚款B.由县级以上卫生行政部门责令改正C.由县级以上卫生行政部门限期整顿D.依法赔偿E.依法追究刑事责任
李某自某商场购得某电饭锅,后因质量问题电饭锅爆炸,炸伤李某。根据《合同法》,李某可请求商场承担何种民事责任?()
消防技术服务机构对某商业大厦中的湿式自动喷水灭火系统进行验收前检测。消防技术服务机构人员将末端试水装置打开,湿式报警阀、压力开关相继动作,主泵启动,运行5min后,在业主建议下,将其余各层喷淋系统给水管网上的试水阀打开,观察给水管是否通畅。全部试水阀打开1
人的品质和行为准则是________。
预算外资金是()性质的资金。
WhilewesterngovernmentsworryoverthethreatofEbola,amorepervasivebutfarlessharmful【C1】______isspreadingthroughth
有下列程序#include<stdio.h>intfun(char*s,char*t){intc=0:char*p,*q;while(*s){P=s;q=t;wh
簡潔
最新回复
(
0
)