title: Prokaryotic extracellular enzymatic activity in relation to biomass production and respiration in the meso- and bathypelagic waters of the (sub)tropical Atlantic.
abstract: Prokaryotic extracellular enzymatic activity, abundance, heterotrophic production and respiration were determined in the meso- and bathypelagic (sub)tropical North Atlantic. While prokaryotic heterotrophic production (PHP) decreased from the lower euphotic layer to the bathypelagic waters by two orders of magnitude, prokaryotic abundance and cell-specific PHP decreased only by one order of magnitude. In contrast to cell-specific PHP, cell-specific extracellular enzymatic activity (alpha- and beta-glucosidase, leucine aminopeptidase, alkaline phosphatase) increased with depth as did cell-specific respiration rates. Cell-specific alkaline phosphatase activity increased from the intermediate water masses to the deep waters up to fivefold. Phosphate concentrations, however, varied only by a factor of two between the different water masses, indicating that phosphatase activity is not related to phosphate availability in the deep waters. Generally, cell-specific extracellular enzymatic activities were inversely related to cell-specific prokaryotic leucine incorporation. Thus, it is apparent that the utilization of deep ocean organic matter is linked to higher cell-specific extracellular enzymatic activity and respiration and lower cell-specific PHP than in surface waters.
authors.affiliation: Facultad de Ciencias del Mar, Universidad de Las Palmas de Gran Canaria, Campus Universitario de Tafira, 35017 Las Palmas de Gran Canaria, Spain. federico.baltar102@doctorandos.ulpgc.es
authors.forename: Federico
authors.initials: F
authors.lastname: Baltar
authors.forename: Javier
authors.initials: J
authors.lastname: Arístegui
authors.forename: Eva
authors.initials: E
authors.lastname: Sintes
authors.forename: Hendrik M
authors.initials: HM
authors.lastname: van Aken
authors.forename: Josep M
authors.initials: JM
authors.lastname: Gasol
authors.forename: Gerhard J
authors.initials: GJ
authors.lastname: Herndl
mesh_terms: D000469:Alkaline Phosphatase / Q000032:analysis; D001105:Archaea / Q000201:enzymology*; D001267:Atlantic Ocean; D001419:Bacteria / Q000201:enzymology*; D018533:Biomass; D004784:Environmental Monitoring; D005110:Extracellular Space / Q000201:enzymology; D052836:Heterotrophic Processes; D007700:Kinetics; D007931:Leucyl Aminopeptidase / Q000032:analysis; D010710:Phosphates / Q000032:analysis; D010933:Plankton / Q000201:enzymology*; D012623:Seawater / Q000737:chemistry / Q000382:microbiology*; D000520:alpha-Glucosidases / Q000378:metabolism; D001617:beta-Glucosidase / Q000378:metabolism
chemical_list: D010710:Phosphates; D000469:Alkaline Phosphatase; D000520:alpha-Glucosidases; D001617:beta-Glucosidase; D007931:Leucyl Aminopeptidase