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| Titel |
Temporal variability of hypoxic zones |
| VerfasserIn |
Holger Brix, Curtis Deutsch, Taka Ito, Hartmut Frenzel, LuAnne Thompson |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250056248
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| Zusammenfassung |
| Oxygen is a critical constraint on marine ecosystems. As oceanic O2 falls to hypoxic
concentrations, habitability for aerobic organisms decreases rapidly. We show that the spatial
extent of hypoxia is highly sensitive to small changes in the ocean’s O2 content, and that this
sensitivity is strongest at suboxic concentrations, where anaerobic metabolisms predominate.
In model-based reconstructions of historical oxygen changes, the world’s largest suboxic
zone, in the Pacific Ocean, varies in size by two-fold. We investigate the causes and
mechanisms behind these changes on seasonal and decadal time-scales. Small changes in the
depth of the tropical and subtropical thermocline driven by Pacific climate are the primary
cause of low-O2 variability on decadal time-scales because thermocline depth has a
multiplicative effect on the export of organic matter from surface waters and the fraction
of it that is respired within the uplifted waters. These results imply even larger
fluctuations in the rate of nitrogen removal via denitrification, creating a link between
decadal climate oscillations and the nutrient limitation of marine photosynthesis. |
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