The results about the false health of phytoplankton allow scientists using computer models to re-create the movement of carbon around the world much more accurately. Resource managers will become more knowledgeable about where carbon is going and the impact of recreational, industrial or commercial processes that use or produce carbon. Researchers better understand the Earth as an ecosystem, and can incorporate these findings in future modeling, analysis and predictions.

While satellite data from NASA's Sea-viewing Wide Field-of-view Sensor played an important part in the study, the real cornerstone of the discovery was ship-based measurements of fluorescence.

Fluorescence occurs when plants absorb sunlight and some of that energy is given back off again as red light. Scientists looked at approximately 140,000 measurements of fluorescence made from 1994 to 2006 along 36,040 miles of ship tracks. They found that phytoplankton give off much more fluorescence when the plants do not have sufficient iron. It is this signal they used to fingerprint what parts of the ocean are iron-stressed and what parts are nitrogen-stressed.

It is important that scientists understand how ocean plants behave because all plants play a critical role in maintaining a healthy planet. Plants annually take up billions of tons of carbon dioxide from the atmosphere through photosynthesis and use this carbon to create the food that nearly all other organisms on Earth depend on for life.

Nutrients that make ocean plants thrive, such as nitrogen and phosphate, mostly come from the deep parts of the ocean, when water is mixed by the wind. Iron also can come from dust blowing in the air.

Approximately half of the photosynthesis on Earth occurs in the oceans, and the remainder on land. Ocean and land plants share the same basic requirements for photosynthesis and
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Contact: Rob Gutro
rgutro@pop900.gsfc.nasa.gov
301-286-4044
NASA/Goddard Space Flight Center
31-Aug-2006