What controls phytoplankton production in nutrient-rich areas of the open sea?
The oceans play a critical role in regulating the global carbon cycle. Deep-ocean waters are roughly 200% supersaturated with CO{sub 2} compared to surface waters, which are in contact with the atmosphere. This difference is due to the flux of photosynthetically derived organic material from surface...
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2008
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| Online Access: | http://www.osti.gov/servlets/purl/10111942 https://www.osti.gov/biblio/10111942 |
| Summary: | The oceans play a critical role in regulating the global carbon cycle. Deep-ocean waters are roughly 200% supersaturated with CO{sub 2} compared to surface waters, which are in contact with the atmosphere. This difference is due to the flux of photosynthetically derived organic material from surface to deep waters and its subsequent remineralization, i.e. the ``biological pump``. The pump is a complex phytoplankton-based ecosystem. the paradoxical nature of ocean regions containing high nutrients and low phytoplankton populations has intrigued biological oceanographers for many years. Hypotheses to explain the paradox include the regulation of productivity by light, temperature, zooplankton grazing, and trace metal limitation and/or toxicity. To date, none of the hypotheses, or combinations thereof, has emerged as a widely accepted explanation for why the nitrogen and phosphorus are not depleted in these regions of the oceans. Recently, new evidence has emerged which supports the hypothesis that iron limitation regulates primary production in these areas. This has stimulated discussions of the feasibility of fertilizing parts the Southern Ocean with iron, and thus sequestering additional atmospheric CO{sub 2} in the deep oceans, where it would remain over the next few centuries. The economic, social, and ethical concerns surrounding such a proposition, along with the outstanding scientific issues, call for rigorous discussion and debate on the regulation of productivity in these regions. To this end, The American Society of Limnology and Oceanography (ASLO) held a Special Symposium on the topic Feb. 22--24th, 1991. Participants included leading authorities, from the US and abroad, on physical, chemical, and biological oceanography, plant physiology, microbiology, and trace metal chemistry. Representatives from government agencies and industry were also present. |
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