title: Vertical distribution of major photosynthetic picoeukaryotic groups in stratified marine waters.
abstract: Photosynthetic picoeukaryotes (PPEs) are fundamental contributors to oceanic primary production and form diverse communities dominated by prymnesiophytes, chlorophytes, pelagophytes and chrysophytes. Here, we studied the vertical distribution of these major groups in two offshore regions of the northern Iberian Peninsula during summer stratification. We performed a fine-scale vertical sampling (every ∼2 m) across the DCM and used fluorescence in situ hybridization (FISH) to determine the PPE composition and to explore the possible segregation of target groups in the light, nutrient and temperature gradients. Chlorophytes, pelagophytes and prymnesiophytes, in this order of abundance, accounted for the total PPEs recorded by flow cytometry in the Avilés canyon, and for more than half in the Galicia Bank, whereas chrysophytes were undetected. Among the three detected groups, often the prymnesiophytes were dominant in biomass. In general, all groups were present throughout the water column with abundance peaks around the DCM, but their distributions differed: pelagophytes were located deeper than the other two groups, chlorophytes presented two peaks and prymnesiophytes exhibited surface abundances comparable to those at the DCM. This study offers first indications that the vertical distribution of different PPE groups is heterogeneous within the DCM.
authors.affiliation: Department of Marine Biology and Oceanography, Institut de Ciències del Mar (CSIC), Barcelona, Catalonia, Spain.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Cabello
authors.affiliation: Instituto Español de Oceanografía (IEO), Centro oceanográfico de Xixón, Xixón, Spain.
authors.forename: Mikel
authors.initials: M
authors.lastname: Latasa
authors.affiliation: Department of Marine Biology and Oceanography, Institut de Ciències del Mar (CSIC), Barcelona, Catalonia, Spain.
authors.forename: Irene
authors.initials: I
authors.lastname: Forn
authors.affiliation: Instituto Español de Oceanografía (IEO), Centro oceanográfico de Xixón, Xixón, Spain.|Division of Biological and Environmental Sciences and Engineering, Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia.
authors.forename: Xosé Anxelu G
authors.initials: XA
authors.lastname: Morán
authors.affiliation: Department of Marine Biology and Oceanography, Institut de Ciències del Mar (CSIC), Barcelona, Catalonia, Spain.
authors.forename: Ramon
authors.initials: R
authors.lastname: Massana
mesh_terms: D018533:Biomass; D056890:Eukaryota / Q000502:physiology*; D017404:In Situ Hybridization, Fluorescence; D008027:Light; D009792:Oceans and Seas; D010788:Photosynthesis / Q000502:physiology*; D012623:Seawater / Q000382:microbiology*