Continental erosion and the Cenozoic rise of marine diatoms

Marine diatoms are silica-precipitating microalgae that account for over half of organic carbon burial in marine sediments and thus they play a key role in the global carbon cycle. Their evolutionary expansion during the Cenozoic era (66 Ma to present) has been associated with a superior competitive...

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Published in:Proceedings of the National Academy of Sciences - PNAS 2015-04, Vol.112 (14), p.4239-4244
Main Authors: Cermeño, Pedro, Falkowski, Paul G., Romero, Oscar E., Schaller, Morgan F., Vallina, Sergio M.
Format: Article
Language:English
Subjects:
Atmosphere
Biological Evolution
Biological Sciences
Carbon Cycle
Cenozoic
Diatoms - physiology
Earth (Planet)
Ecology
Ecosystem
Evolution, Planetary
Fossils
Geologic Sediments
Lithium
Lithium - chemistry
Marine ecology
Marine ecosystems
Marine sediments
Mathematical models
Microalgae - physiology
Oceans
Oceans and Seas
Organic carbon
Physical Sciences
Plankton
Seawater
Sediments
Silica
Silicates
Silicic Acid - chemistry
Weather
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Summary:Marine diatoms are silica-precipitating microalgae that account for over half of organic carbon burial in marine sediments and thus they play a key role in the global carbon cycle. Their evolutionary expansion during the Cenozoic era (66 Ma to present) has been associated with a superior competitive ability for silicic acid relative to other siliceous plankton such as radiolarians, which evolved by reducing the weight of their silica test. Here we use a mathematical model in which diatoms and radiolarians compete for silicic acid to show that the observed reduction in the weight of radiolarian tests is insufficient to explain the rise of diatoms. Using the lithium isotope record of seawater as a proxy of silicate rock weathering and erosion, we calculate changes in the input flux of silicic acid to the oceans. Our results indicate that the long-term massive erosion of continental silicates was critical to the subsequent success of diatoms in marine ecosystems over the last 40 My and suggest an increase in the strength and efficiency of the oceanic biological pump over this period.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.1412883112