title: Ubiquitous healthy diatoms in the deep sea confirm deep carbon injection by the biological pump.
abstract: The role of the ocean as a sink for CO2 is partially dependent on the downward transport of phytoplankton cells packaged within fast-sinking particles. However, whether such fast-sinking mechanisms deliver fresh organic carbon down to the deep bathypelagic sea and whether this mechanism is prevalent across the ocean requires confirmation. Here we report the ubiquitous presence of healthy photosynthetic cells, dominated by diatoms, down to 4,000 m in the deep dark ocean. Decay experiments with surface phytoplankton suggested that the large proportion (18%) of healthy photosynthetic cells observed, on average, in the dark ocean, requires transport times from a few days to a few weeks, corresponding to sinking rates (124-732 m d(-1)) comparable to those of fast-sinking aggregates and faecal pellets. These results confirm the expectation that fast-sinking mechanisms inject fresh organic carbon into the deep sea and that this is a prevalent process operating across the global oligotrophic ocean.
authors.affiliation: Red Sea Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia.|Department of Global Change Research, IMEDEA (CSIC-UIB), Miquel Marqués 21, Esporles 07190, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Agusti
authors.affiliation: Department of Biology, Campus de Excelencia Internacional del Mar (CEIMAR), Universidad de Cádiz, Puerto Real (Cádiz) 11510, Spain.
authors.forename: J I
authors.initials: JI
authors.lastname: González-Gordillo
authors.affiliation: Institut de Ciències del Mar, CSIC, Passeig Marítim de la Barceloneta 37-49, Barcelona, Catalunya E 08003, Spain.
authors.forename: D
authors.initials: D
authors.lastname: Vaqué
authors.affiliation: Institut de Ciències del Mar, CSIC, Passeig Marítim de la Barceloneta 37-49, Barcelona, Catalunya E 08003, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Estrada
authors.affiliation: Department of Global Change Research, IMEDEA (CSIC-UIB), Miquel Marqués 21, Esporles 07190, Spain.
authors.forename: M I
authors.initials: MI
authors.lastname: Cerezo
authors.affiliation: Institut de Ciències del Mar, CSIC, Passeig Marítim de la Barceloneta 37-49, Barcelona, Catalunya E 08003, Spain.
authors.forename: G
authors.initials: G
authors.lastname: Salazar
authors.affiliation: Institut de Ciències del Mar, CSIC, Passeig Marítim de la Barceloneta 37-49, Barcelona, Catalunya E 08003, Spain.
authors.forename: J M
authors.initials: JM
authors.lastname: Gasol
authors.affiliation: Red Sea Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia.|Department of Global Change Research, IMEDEA (CSIC-UIB), Miquel Marqués 21, Esporles 07190, Spain.
authors.forename: C M
authors.initials: CM
authors.lastname: Duarte
mesh_terms: D002245:Carbon Dioxide; D057965:Carbon Sequestration; D017377:Diatoms; D009792:Oceans and Seas; D010839:Phytoplankton; D012623:Seawater
chemical_list: D002245:Carbon Dioxide