title: Decoupling physical from biological processes to assess the impact of viruses on a mesoscale algal bloom.
abstract: Phytoplankton blooms are ephemeral events of exceptionally high primary productivity that regulate the flux of carbon across marine food webs [1-3]. Quantification of bloom turnover [4] is limited by a fundamental difficulty to decouple between physical and biological processes as observed by ocean color satellite data. This limitation hinders the quantification of bloom demise and its regulation by biological processes [5, 6], which has important consequences on the efficiency of the biological pump of carbon to the deep ocean [7-9]. Here, we address this challenge and quantify algal blooms' turnover using a combination of satellite and in situ data, which allows identification of a relatively stable oceanic patch that is subject to little mixing with its surroundings. Using a newly developed multisatellite Lagrangian diagnostic, we decouple the contributions of physical and biological processes, allowing quantification of a complete life cycle of a mesoscale (∼10-100 km) bloom of coccolithophores in the North Atlantic, from exponential growth to its rapid demise. We estimate the amount of organic carbon produced during the bloom to be in the order of 24,000 tons, of which two-thirds were turned over within 1 week. Complimentary in situ measurements of the same patch area revealed high levels of specific viruses infecting coccolithophore cells, therefore pointing at the importance of viral infection as a possible mortality agent. Application of the newly developed satellite-based approaches opens the way for large-scale quantification of the impact of diverse environmental stresses on the fate of phytoplankton blooms and derived carbon in the ocean.
authors.affiliation: Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Yoav
authors.initials: Y
authors.lastname: Lehahn
authors.affiliation: Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot 76100, Israel. Electronic address: ilan.koren@weizmann.ac.il.
authors.forename: Ilan
authors.initials: I
authors.lastname: Koren
authors.affiliation: Department of Plant Sciences, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Daniella
authors.initials: D
authors.lastname: Schatz
authors.affiliation: Department of Plant Sciences, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Miguel
authors.initials: M
authors.lastname: Frada
authors.affiliation: Department of Plant Sciences, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Uri
authors.initials: U
authors.lastname: Sheyn
authors.affiliation: School of Marine Science, University of Maine, Orono, ME 04469-5706, USA.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Boss
authors.affiliation: Department of Geophysical, Atmospheric and Planetary Sciences, Tel Aviv University, Tel Aviv 6997801, Israel.
authors.forename: Shai
authors.initials: S
authors.lastname: Efrati
authors.affiliation: Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Yinon
authors.initials: Y
authors.lastname: Rudich
authors.affiliation: Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Miri
authors.initials: M
authors.lastname: Trainic
authors.affiliation: Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot 76100, Israel; Department of Plant Sciences, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Shlomit
authors.initials: S
authors.lastname: Sharoni
authors.affiliation: Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08901, USA.
authors.forename: Christian
authors.initials: C
authors.lastname: Laber
authors.affiliation: Hollings Marine Laboratory, College of Charleston, Charleston, SC 29412, USA.
authors.forename: Giacomo R
authors.initials: GR
authors.lastname: DiTullio
authors.affiliation: Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA.
authors.forename: Marco J L
authors.initials: MJ
authors.lastname: Coolen
authors.affiliation: University of the Azores, Horta, Azores 9901-862, Faial, Portugal.
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Martins
authors.affiliation: Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA.
authors.forename: Benjamin A S
authors.initials: BA
authors.lastname: Van Mooy
authors.affiliation: Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08901, USA.
authors.forename: Kay D
authors.initials: KD
authors.lastname: Bidle
authors.affiliation: Department of Plant Sciences, Weizmann Institute of Science, Rehovot 76100, Israel. Electronic address: assaf.vardi@weizmann.ac.il.
authors.forename: Assaf
authors.initials: A
authors.lastname: Vardi
mesh_terms: D001267:Atlantic Ocean; D005068:Eutrophication; D058087:Haptophyta / Q000502:physiology / Q000821:virology*; D010839:Phytoplankton / Q000502:physiology / Q000821:virology*; D058998:Remote Sensing Technology; D018406:Virus Physiological Phenomena; D014872:Water Movements