title: Horizontal and Vertical Distributions of Transparent Exopolymer Particles (TEP) in the NW Mediterranean Sea Are Linked to Chlorophyllaand O2Variability.
abstract: Transparent Exopolymer Particles (TEP) are relevant in particle and carbon fluxes in the ocean, and have economic impact in the desalination industry affecting reverse osmosis membrane fouling. However, general models of their occurrence and dynamics are not yet possible because of the poorly known co-variations with other physical and biological variables. Here, we describe TEP distributions in the NW Mediterranean Sea during late spring 2012, along perpendicular and parallel transects to the Catalan coast. The stations in the parallel transect were sampled at the surface, while the stations in the perpendicular transect were sampled from the surface to the bathypelagic, including the bottom nepheloid layers. We also followed the short-term TEP dynamics along a 2-day cycle in offshore waters. TEP concentrations in the area ranged from 4.9 to 122.8 and averaged 31.4 ± 12.0 μg XG eq L-1. The distribution of TEP measured in transects parallel to the Catalan Coast correlated those of chlorophylla(Chla) in May but not in June, when higher TEP-values with respect to Chla were observed. TEP horizontal variability in epipelagic waters from the coast to the open sea also correlated to that of Chla, O2(that we interpret as a proxy of primary production) and bacterial production (BP). In contrast, the TEP vertical distributions in epipelagic waters were uncoupled from those of Chla, as TEP maxima were located above the deep chlorophyll maxima. The vertical distribution of TEP in the epipelagic zone was correlated with O2and BP, suggesting combined phytoplankton (through primary production) and bacterial (through carbon reprocessing) TEP sources. However, no clear temporal patterns arose during the 2-day cycle. In meso- and bathypelagic waters, where phytoplanktonic sources are minor, TEP concentrations (10.1 ± 4.3 μg XG eq l-1) were half those in the epipelagic, but we observed relative TEP increments coinciding with the presence of nepheloid layers. These TEP increases were not paralleled by increases in particulate organic carbon, indicating that TEP are likely to act as aggregating agents of the mostly inorganic particles present in these bottom nepheloid layers.
authors.affiliation: Biologia Marina i Oceanografia, Consejo Superior de Investigaciones Científicas, Institut de Ciències del Mar Barcelona, Spain.
authors.forename: Eva
authors.initials: E
authors.lastname: Ortega-Retuerta
authors.affiliation: Biologia Marina i Oceanografia, Consejo Superior de Investigaciones Científicas, Institut de Ciències del Mar Barcelona, Spain.
authors.forename: Maria M
authors.initials: MM
authors.lastname: Sala
authors.affiliation: Biologia Marina i Oceanografia, Consejo Superior de Investigaciones Científicas, Institut de Ciències del Mar Barcelona, Spain.
authors.forename: Encarna
authors.initials: E
authors.lastname: Borrull
authors.affiliation: Biologia Marina i Oceanografia, Consejo Superior de Investigaciones Científicas, Institut de Ciències del Mar Barcelona, Spain.
authors.forename: Mireia
authors.initials: M
authors.lastname: Mestre
authors.affiliation: Biologia Marina i Oceanografia, Consejo Superior de Investigaciones Científicas, Institut de Ciències del Mar Barcelona, Spain.
authors.forename: Fran L
authors.initials: FL
authors.lastname: Aparicio
authors.affiliation: Biologia Marina i Oceanografia, Consejo Superior de Investigaciones Científicas, Institut de Ciències del Mar Barcelona, Spain.
authors.forename: Rachele
authors.initials: R
authors.lastname: Gallisai
authors.affiliation: Biologia Marina i Oceanografia, Consejo Superior de Investigaciones Científicas, Institut de Ciències del Mar Barcelona, Spain.
authors.forename: Carolina
authors.initials: C
authors.lastname: Antequera
authors.affiliation: Biologia Marina i Oceanografia, Consejo Superior de Investigaciones Científicas, Institut de Ciències del Mar Barcelona, Spain.
authors.forename: Cèlia
authors.initials: C
authors.lastname: Marrasé
authors.affiliation: Biologia Marina i Oceanografia, Consejo Superior de Investigaciones Científicas, Institut de Ciències del Mar Barcelona, Spain.
authors.forename: Francesc
authors.initials: F
authors.lastname: Peters
authors.affiliation: Biologia Marina i Oceanografia, Consejo Superior de Investigaciones Científicas, Institut de Ciències del Mar Barcelona, Spain.
authors.forename: Rafel
authors.initials: R
authors.lastname: Simó
authors.affiliation: Biologia Marina i Oceanografia, Consejo Superior de Investigaciones Científicas, Institut de Ciències del Mar Barcelona, Spain.
authors.forename: Josep M
authors.initials: JM
authors.lastname: Gasol
keywords: Mediterranean Sea; bacteria; carbon; chlorophyll a; transparent exopolymer particles