研究:上个世纪海洋浮游植物数量下降
文章来源:未知 文章作者:meng 发布时间:2010-07-29 00:44 字体: [ ]  进入论坛
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A new article published in the 29 July issue of the international journal Nature reveals for the first time that microscopic1 marine2 algae3(海藻类) known as "phytoplankton(浮游植物) " have been declining globally over the 20th century. Phytoplankton forms the basis of the marine food chain and sustains diverse assemblages(集合体,聚集物) of species ranging from tiny zooplankton(浮游动物) to large marine mammals, seabirds, and fish. Says lead author Daniel Boyce, "Phytoplankton is the fuel on which marine ecosystems4 run. A decline of phytoplankton affects everything up the food chain, including humans." Using an unprecedented5 collection of historical and recent oceanographic(海洋学的) data, a team from Canada's Dalhousie University documented phytoplankton declines of about 1% of the global average per year. This trend is particularly well documented in the Northern Hemisphere and after 1950, and would translate into a decline of approximately 40% since 1950. The scientists found that long-term phytoplankton declines were negatively correlated with rising sea surface temperatures and changing oceanographic conditions.

The goal of the three-year analysis was to resolve one of the most pressing issues in oceanography, namely to answer the seemingly simple question of whether the ocean is becoming more (or less)  green with algae. Previous analyses had been limited to more recent satellite data (consistently一贯地,一致地 available since 1997) and have yielded variable results. To extend the record into the past, the authors analysed a unique compilation6 of historical measurements of ocean transparency going back to the very beginning of quantitative7 oceanography in the late 1800s, and combined these with additional samples of phytoplankton pigment8 (chlorophyll) from ocean-going research vessels9. The end result was a database of just under half a million observations which enabled the scientists to estimate phytoplankton trends over the entire globe going back to the year 1899.

The scientists report that most phytoplankton declines occurred in polar and tropical regions and in the open oceans where most phytoplankton production occurs. Rising sea surface temperatures were negatively correlated with phytoplankton growth over most of the globe, especially close to the equator(赤道) . Phytoplankton need both sunlight and nutrients11 to grow; warm oceans are strongly stratified(分层) , which limits the amount of nutrients that are delivered from deeper waters to the surface ocean. Rising temperatures may contribute to making the tropical oceans even more stratified, leading to increasing nutrient10 limitation and phytoplankton declines. The scientists also found that large-scale climate fluctuations12(波动,变动) , such as the El-Niño Southern Oscillation (ENSO), affect phytoplankton on a year-to-year basis, by changing short-term oceanographic conditions.

The findings contribute to a growing body of scientific evidence indicating that global warming is altering the fundamentals of marine ecosystems. Says co-author Marlon Lewis, "Climate-driven phytoplankton declines are another important dimension of global change in the oceans, which are already stressed by the effects of fishing and pollution. Better observational tools and scientific understanding are needed to enable accurate forecasts of the future health of the ocean." Explains co-author Boris Worm, "Phytoplankton are a critical part of our planetary life support system. They produce half of the oxygen we breathe, draw down(引来,招致) surface CO2, and ultimately support all of our fisheries(渔业,渔场) . An ocean with less phytoplankton will function differently, and this has to be accounted for in our management efforts."



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1 microscopic nDrxq     
adj.微小的,细微的,极小的,显微的
参考例句:
  • It's impossible to read his microscopic handwriting.不可能看清他那极小的书写字迹。
  • A plant's lungs are the microscopic pores in its leaves.植物的肺就是其叶片上微细的气孔。
2 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。
3 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。
4 ecosystems 94cb0e40a815bea1157ac8aab9a5380d     
n.生态系统( ecosystem的名词复数 )
参考例句:
  • There are highly sensitive and delicately balanced ecosystems in the forest. 森林里有高度敏感、灵敏平衡的各种生态系统。 来自《简明英汉词典》
  • Madagascar's ecosystems range from rainforest to semi-desert. 马达加斯加生态系统类型多样,从雨林到半荒漠等不一而足。 来自辞典例句
5 unprecedented 7gSyJ     
adj.无前例的,新奇的
参考例句:
  • The air crash caused an unprecedented number of deaths.这次空难的死亡人数是空前的。
  • A flood of this sort is really unprecedented.这样大的洪水真是十年九不遇。
6 compilation kptzy     
n.编译,编辑
参考例句:
  • One of the first steps taken was the compilation of a report.首先采取的步骤之一是写一份报告。
  • The compilation of such diagrams,is of lasting value for astronomy.绘制这样的图对天文学有永恒的价值。
7 quantitative TCpyg     
adj.数量的,定量的
参考例句:
  • He said it was only a quantitative difference.他说这仅仅是数量上的差别。
  • We need to do some quantitative analysis of the drugs.我们对药物要进行定量分析。
8 pigment gi0yg     
n.天然色素,干粉颜料
参考例句:
  • The Romans used natural pigments on their fabrics and walls.古罗马人在织物和墙壁上使用天然颜料。
  • Who thought he might know what the skin pigment phenomenon meant.他自认为可能知道皮肤色素出现这种现象到底是怎么回事。
9 vessels fc9307c2593b522954eadb3ee6c57480     
n.血管( vessel的名词复数 );船;容器;(具有特殊品质或接受特殊品质的)人
参考例句:
  • The river is navigable by vessels of up to 90 tons. 90 吨以下的船只可以从这条河通过。 来自《简明英汉词典》
  • All modern vessels of any size are fitted with radar installations. 所有现代化船只都有雷达装置。 来自《现代汉英综合大词典》
10 nutrient 3vpye     
adj.营养的,滋养的;n.营养物,营养品
参考例句:
  • Magnesium is the nutrient element in plant growth.镁是植物生长的营养要素。
  • The roots transmit moisture and nutrient to the trunk and branches.根将水分和养料输送到干和枝。
11 nutrients 6a1e1ed248a3ac49744c39cc962fb607     
n.(食品或化学品)营养物,营养品( nutrient的名词复数 )
参考例句:
  • a lack of essential nutrients 基本营养的缺乏
  • Nutrients are absorbed into the bloodstream. 营养素被吸收进血液。 来自《简明英汉词典》
12 fluctuations 5ffd9bfff797526ec241b97cfb872d61     
波动,涨落,起伏( fluctuation的名词复数 )
参考例句:
  • He showed the price fluctuations in a statistical table. 他用统计表显示价格的波动。
  • There were so many unpredictable fluctuations on the Stock Exchange. 股票市场瞬息万变。
TAG标签: species ocean Marine
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