露脊鲸缘何徘徊于缅因湾
文章来源:未知 文章作者:enread 发布时间:2011-04-27 05:01 字体: [ ]  进入论坛
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As they might with most endangered animals, scientists consider the whereabouts and activities of right whales(露脊鲸) extremely important. "It is helpful to know where they go, why they go there and what they do when they're there," says Mark F. Baumgartner of the biology department at the Woods Hole Oceanographic Institution (WHOI). Baumgartner and his colleagues studied the behavior of right whales and sei whales—both endangered species of baleen1 whales(须鲸) —in the waters of the Gulf2 of Maine to the east of Nantucket. They found that the location, the length of stay, and perhaps the very abundance of the whales may be dependent on an interesting vertical3 migration4 pattern by the copepods on which the whales feed. It seems to be a case, he said, of "how the behavior of the prey5 influences the behavior of the whales."

The algae6-eating copepod, Calanus finmarchicus, appears to migrate up and down in the water column to avoid being eaten by predators7 such as herring and sand lance. Since these fish need to see their prey in order to feed, copepods often remain at depths where sunlight will not penetrate8 during the daytime. Under cover of night, they leave this deep, dark refuge, swim to the surface, and feed on algae in relative safety.

In turn, this pattern, the scientists report in a recent issue of the journal Marine9 Ecology Progress Series, has a "dramatic impact" on the behavior and whereabouts of the whales. They found that right whales, which are capable of feeding at depths of 450 to 600 feet below the surface, continued to stay in the area and feed on copepods deep in the water column during the day. The sei whales, on the other hand, were "significantly less abundant" when the copepods displayed vertical migration. Unlike the right whales, the sei whales probably cannot feed at depth during the day, so they may leave the area in search of better feeding conditions elsewhere.

For reasons not well understood, the critically endangered right whale is vulnerable to being hit by ships while at the surface. Baumgartner points out that nighttime may prove particularly dangerous for right whales as they feed on copepods that have migrated to the surface, yet captains piloting ships in the dark have no way to see and avoid the whales.

"Our study also helps us understand why right whales stick around in this area, from about mid10 April to mid June," Baumgartner said. Because of their ability to feed below the surface, "they are able to out-compete the herring" for food, he said.

It had been thought that the recovery of herring stocks in the last decade might further threaten the right whale by depleting11 its food supply, Baumgartner said. But these latest observations—along with a rise in the North Atlantic right whale population from roughly 300 to 400 since 1999—suggest that herring recovery does not threaten the right whale population, he said.

At the same time, the herring and sand lance, by inducing the copepods' vertical migration behavior, "are likely influencing the distribution and abundance of sei whales" in that area, the researchers report. However, since the sei whale population numbers in the thousands, Baumgartner said their tendency to go elsewhere to look for food is not as great a concern as it would be for the right whale.

"The good news is that the recovery of herring stocks is not going to be a problem for the right whale population," Baumgartner said. "The bad news is that if the right whales are feeding at the surface at night, they are at greater risk for ship strikes than we had thought earlier."

The study was conducted during the spring seasons of 2005, 2006 and 2007.



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1 baleen ZPey2     
n.鲸须
参考例句:
  • Other baleen whales have splash guards too,but not like this.一些须鲸物种头顶也有护住喷水孔的构造,但并不长成这样。
  • Baleen whales often appear in this region. Be careful!这一带经常有须鲸出没,要注意安全啊。
2 gulf 1e0xp     
n.海湾;深渊,鸿沟;分歧,隔阂
参考例句:
  • The gulf between the two leaders cannot be bridged.两位领导人之间的鸿沟难以跨越。
  • There is a gulf between the two cities.这两座城市间有个海湾。
3 vertical ZiywU     
adj.垂直的,顶点的,纵向的;n.垂直物,垂直的位置
参考例句:
  • The northern side of the mountain is almost vertical.这座山的北坡几乎是垂直的。
  • Vertical air motions are not measured by this system.垂直气流的运动不用这种系统来测量。
4 migration mDpxj     
n.迁移,移居,(鸟类等的)迁徙
参考例句:
  • Swallows begin their migration south in autumn.燕子在秋季开始向南方迁移。
  • He described the vernal migration of birds in detail.他详细地描述了鸟的春季移居。
5 prey g1czH     
n.被掠食者,牺牲者,掠食;v.捕食,掠夺,折磨
参考例句:
  • Stronger animals prey on weaker ones.弱肉强食。
  • The lion was hunting for its prey.狮子在寻找猎物。
6 algae tK6yW     
n.水藻,海藻
参考例句:
  • Most algae live in water.多数藻类生长在水中。
  • Algae grow and spread quickly in the lake.湖中水藻滋蔓。
7 predators 48b965855934a5395e409c1112d94f63     
n.食肉动物( predator的名词复数 );奴役他人者(尤指在财务或性关系方面)
参考例句:
  • birds and their earthbound predators 鸟和地面上捕食它们的动物
  • The eyes of predators are highly sensitive to the slightest movement. 捕食性动物的眼睛能感觉到最细小的动静。 来自《简明英汉词典》
8 penetrate juSyv     
v.透(渗)入;刺入,刺穿;洞察,了解
参考例句:
  • Western ideas penetrate slowly through the East.西方观念逐渐传入东方。
  • The sunshine could not penetrate where the trees were thickest.阳光不能透入树木最浓密的地方。
9 marine 77Izo     
adj.海的;海生的;航海的;海事的;n.水兵
参考例句:
  • Marine creatures are those which live in the sea. 海洋生物是生存在海里的生物。
  • When the war broke out,he volunteered for the Marine Corps.战争爆发时,他自愿参加了海军陆战队。
10 mid doTzSB     
adj.中央的,中间的
参考例句:
  • Our mid-term exam is pending.我们就要期中考试了。
  • He switched over to teaching in mid-career.他在而立之年转入教学工作。
11 depleting ae23633b1a5c6c21ae0d93b205d84331     
使大大的减少,使空虚( deplete的现在分词 ); 耗尽,使枯竭
参考例句:
  • Regulations are outlawing certain refrigerants, such as chlorofluorocarbons, which contain ozone-depleting chemicals. 随后出台的政策禁用了部分制冷剂,如破坏臭氧层的氟氯碳化合物。
  • Aging, being a series of continual losses, can be keenly depleting. 老龄化,作为一个系列的连续亏损,可以清楚地消耗。
TAG标签: whales feed Maine
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