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Climate Change, Ecology, Pollution, Sustainability

Global phytoplankton decline over the past century

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Phytoplankton are microscopic, free-floating plants that form the basis of the aquatic food chain. They also account for half of all photosynthetic activity, and thus produce much of the atmosphere’s oxygen.  Changes in the level of phytoplankton activity would have important implications on the health of the entire ecosystem, including human life.

Using a combination of historical and recent oceanographic data, a 2010 study published in Nature magazine, “Global phytoplankton Decline Over the Past Century,” calculates that the change in the level of phytoplankton activity over the last 100 years.

The study finds that:

  • The annual global rate of decline of phytoplankton has been about 1% relative to the global median.
  • Over the long term, in eight out of ten regions, rising sea surface temperatures were associated with declining phytoplankton. The negative relationship prevailed at low latitudes near the equator, where increased stratification has limited nutrient availability.
  • At high latitudes, rising sea surface temperatures could affect positive phytoplankton growth, since the growth of phytoplankton could have been constrained by light availability and deep mixing.

The study’s findings are consistent with those on the effects of ocean warming on fishing and marine ecosystem. This further underscores the need for more sophisticated tools to support accurate measurement and forecasts of phytoplankton as well as the importance of reduce the causes and impact of climate change.

Tags: oceans, pollution, water

    Writer: | Last updated: September 10, 2010

    Citation: Boyce, Daniel G.; et al. "Global phytoplankton decline over the past century", Nature, July, 2010, Vol. 466, Issue 7306, 591-596. DOI:10.1038/nature09268.

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    Analysis assignments

    Read the study titled "Global phytoplankton Decline Over the Past Century."

    1. Summarize the study in fewer than 40 words.
    2. Express the study's key term(s) in language a lay audience can understand.
    3. Evaluate the study's limitations. (For example: Do the results conflict with those of other reliable studies? Are there weaknesses in the study's data or research design?)

    Read the issue-related New York Times article titled "Oil Plumes May Be More Toxic Than Thought, Scientists Warn."

    1. If you were to rewrite the article based on knowledge of the study, what key changes would you make?

    Newswriting assignments

    1. Write a lead (or headline or nut graph) based on the study.
    2. Spend 60 minutes exploring the issue by accessing sources of information other than the study. Write a lead (or headline or nut graph) based on the study but informed by the new information. Does the new information significantly change what one would write based on the study alone?
    3. Interview two sources with a stake in or knowledge of the issue. Be prepared to provide them with a short summary of the study in order to get their response to it. Write a 400-word article about the study incorporating material from the interviews.
    4. Spend additional time exploring the issue and then write a 1,200-word background article, focusing on major aspects of the issue.