title: Continental erosion and the Cenozoic rise of marine diatoms.
abstract: 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.
authors.affiliation: Departamento de Biología Marina y Oceanografía, Instituto de Ciencias del Mar, 08003 Barcelona, Spain; pedrocermeno@icm.csic.es.
authors.forename: Pedro
authors.initials: P
authors.lastname: Cermeño
authors.affiliation: Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08901; Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ 08854;
authors.forename: Paul G
authors.initials: PG
authors.lastname: Falkowski
authors.affiliation: MARUM - Center for Marine Environmental Sciences, University of Bremen, 28359 Bremen, Germany; and.
authors.forename: Oscar E
authors.initials: OE
authors.lastname: Romero
authors.affiliation: Earth and Environmental Science, Rensselaer Polytechnic Institute, Troy, NY 12180.
authors.forename: Morgan F
authors.initials: MF
authors.lastname: Schaller
authors.affiliation: Departamento de Biología Marina y Oceanografía, Instituto de Ciencias del Mar, 08003 Barcelona, Spain;
authors.forename: Sergio M
authors.initials: SM
authors.lastname: Vallina
mesh_terms: D001272:Atmosphere; D005075:Biological Evolution; D057486:Carbon Cycle; D017377:Diatoms / Q000502:physiology*; D018534:Earth, Planet; D004463:Ecology; D017753:Ecosystem; D019419:Evolution, Planetary; D005580:Fossils; D019015:Geologic Sediments; D008094:Lithium / Q000737:chemistry; D058086:Microalgae / Q000502:physiology*; D009792:Oceans and Seas; D010933:Plankton; D012623:Seawater; D012824:Silicic Acid / Q000737:chemistry; D014887:Weather
chemical_list: D012824:Silicic Acid; D008094:Lithium
keywords: Cenozoic era; biological pump; continental erosion; marine diatoms; silicic acid
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