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  • 1. Ammerman, J.W.
    et al.
    Fuhrman, J.A.
    Hagström, Åke
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Azam, F.
    Bacterioplankton growth in seawater: I.Growth kinetics and cellular characteristics in seawater cultures1984In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 18, p. 31-39Article in journal (Refereed)
  • 2. Andersson, A.
    et al.
    Selstam, E.
    Hagström, Åke
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Vertical Transport of Lipid in Sea Water.1993In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 98, p. 149-155Article in journal (Refereed)
  • 3.
    Andersson, Agneta
    et al.
    Department of Microbiology. University of Urnea. S-901 87 UMEA, Sweden.
    Lee, C.
    Azam, F.
    Hagström, Åke
    Department of Microbiology. University of Urnea. S-901 87 UMEA, Sweden.
    Release of aminoacids and inorganic nutrients by heterotrophic marine microflagellates1985In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 23, p. 99-106Article in journal (Refereed)
    Abstract [en]

    Heterotrophic microflagellates isolated from the Baltic Sea and grown under laboratoryconditions were shown to release dissolved free amino acids (DFAA) when grazing bacteria. Flagellatesreleased 3H-amino acids when fed 3H-leucine-labelled bacteria, and concentrations of aminoacids increased in the experimental medium. Serine showed a strong positive correlation withflagellate feeding. Aspartic acid, glutamic acid and ornithine also increased more than other aminoacids. During consumption of bacteria, the flagellates released 13% of the ingested nitrogen asammonia, and 30 % of the ingested phosphorus as phosphate. In a field experiment off Scripps Pier, wemeasured bacterial production, flagellate abundance, and concentration of DFAA over a 28 h period.The concentration of DFAA showed a covariation with the flagellate numbers. Results from our fieldand laboratory experiments suggest that flagellates may be a source of DFAA in the sea. 

  • 4. Fuhrman, J.A.
    et al.
    Eppley, R.W.
    Hagström, Åke
    Department of Microbiology. University of Urnea. S-901 87 UMEA, Sweden.
    Azam, F.
    Diel variations in bacterioplankton, phytoplankton, and related parameters in the Southern California Bight.1985In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 27, p. 9-20Article in journal (Refereed)
    Abstract [en]

    The principal objectives of this study were (i) to determine the extent of coupling betweenphytoplankton and microheterotrophs on the shelf off Southern California. (ii) to compare differentmeasures of primary and bacterial secondary production, and (iii) to assess whether sampling timesshould be as strictly controlled for microheterotroph as for autotroph studies. Two diel cycles (May andOctober) were studied by sampling an isotherm as the ship followed paired submerged drogues. Wefound significant die1 changes of chlorophyll, 14C bicarbonate incorporation, bacterial abundance andthymidine incorporation, frequency of dividing bacterial cells (FDC), abundance of non-pigmentedflagellates, particulate organic carbon and nitrogen and their ratios, and dissolved oxygen. Theseparameters all had higher values dunng daylight hours than at night, showing close coupling betweenthe phytoplankton (light-forced) and the microheterotrophs. The ratio of in vivo to extractedchlorophyll a fluorescence, however, displayed a maximum at midnight and minimum at midday,suggesting an endogenous rhythm. Primary production measured by the 14C method was similar to netproduction inferred from in situ oxygen changes. Short-lived peaks in FDC values suggested partlysynchronized bacterial division. 

  • 5.
    Hagström, Åke
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Ammerman, J.W.
    Henrichs, S.
    Azam, F.
    Bacterioplankton growth in seawater: II. Organic matter utilization during steady-state growth in seawater cultures1984In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 18, p. 41-48Article in journal (Refereed)
  • 6.
    Hagström, Åke
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Andersson, A.
    Larsson, U.
    Size-selective grazing by a microflagellate on pelagic bacteria1986In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 33, p. 51-57Article in journal (Refereed)
  • 7.
    Hagström, Åke
    et al.
    Department of Microbiology, University of Umeå.
    Azam, F.
    Andersson, A.
    Wikner, J.
    Rassoulzadegan, F.
    Microbial loop in an oligotrophic pelagic marine ecosystem: Possible roles of cyanobacteria and nanoflagellates in the organic fluxes1988In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 49, p. 171-178Article in journal (Refereed)
    Abstract [en]

    In an attempt to quantify the organic fluxes within the microbial loop of oligotrophicMediterranean water, organic pools and production rates were monitored. The production of cyanobacteriaand its dynamics dominated the overall productivity in the system. The largest standing stock wasthat of the bacterioplankton and its growth consumed 8.3 pg C 1-' d-', hence about 60 % of the primaryproduction was required for bacterial growth. Using the MiniCap technique, we measured a predationon bacteria of 2 6 X 104 bacteria ml-' h-'. This was in good agreement with the bacterial production rateof 2.3 X 104 cells rnl-' h-' Thus, growth and predation were balanced for heterotrophic bacterioplankton.Almost all of this predation on bacteria was due to organisms passing a 12 vm Nuclepore filter. Thisraises the question of what mechanisms channel 60 % of primary production into bacteria. We thereforeoutlined a mass-balance model to illustrate routes that could explain this transfer. According to ourmodel the main flux route is cyanobacteria and concomitantly consumed heterotrophic bacteria carboninto bacterivores. A substantial fraction of the bacterivore and the microplankton carbon is released byexcretion and/or cell lysis, to be used by the heterotrophic bacterioplankton. About 86% of theautotrophic production is balanced by respiration due to heterotrophic bacteria and protozoa, leaving6 % of the primary production to higher trophic levels. This scenario should apply to ecosystems wherebacterial production rate is high and comparable to primary production, and the dominant primaryproducers are cyanobacteria. A significant fraction of the photosynthetically fixed carbon will bemineralized within a simple microbial loop, thus rendering it an energy sink in the foodweb.

  • 8. Horrigan, S.G.
    et al.
    Hagström, Åke
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Koike, I.
    Azam, F.
    Inorganic nitrogen utilization by assemblages of marine bacteria in seawater culture1988In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 50, p. 147-150Article in journal (Refereed)
    Abstract [en]

    Stimulation of heterotrophic bacterial growth by inorganic nitrogen (nitrate and ammonium) was observed in natural assemblages of marine bacteria growth in continuous culture with unsupplemented sea water as primary medium. In the presence of nitrogenous supplements, bacterial numbers increased approximately 3-fold. These results indicate that re-evaluation of the role of heterotrophic bacterioplankton in the pelagic nitrogen cycle may be necessary. 

  • 9. Kozlowsky-Suzuki, Betina
    et al.
    Karjalainen, Mina
    Koski, Marja
    Carlsson, Per
    Stolte, Willem
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Balode, M
    Granéli, Edna
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Disruption of the microbial food web and inhibition of metazooplankton development in the presence of iron and DOM-stimulated Baltic Sea cyanobacteria2007In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 337, p. 15-26Article in journal (Refereed)
  • 10.
    Pinhassi, Jarone
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Winding, A.
    Binnerup, S.
    Zweifel, Ulla Li
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Riemann, Bo
    Hagström, Åke
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Spatial variability in bacterioplankton community composition at the Skagerrak-Kattegat front.2003In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 255, p. 1-13Article in journal (Refereed)
  • 11. Pontarp, Mikael
    et al.
    Sjöstedt, Johanna
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Lundberg, Per
    Experimentally induced habitat filtering in marine bacterial communities2013In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 477, p. 77-U406Article in journal (Refereed)
    Abstract [en]

    We tested the habitat filtering hypothesis by measuring the phylogenetic structure in marine bacterial communities before and after experimentally induced stress. The habitat filtering hypothesis predicts that phylogenetic clustering (mean relatedness) should increase as the environment becomes suitable for only a subset of the original community. We show that community composition and phylogenetic structure were considerably changed with changes in salinity and dissolved organic carbon. Community composition showed no consistent patterns, while the phylogenetic relatedness between species consistently increased with treatment. We have no information about species interactions in our system, but the phylogenetic signal is strong enough to suggest that habitat filtering is the dominant assembly process. Our results support the hypothesis that habitat characteristics and environmental stress can 'filter' a community so that only closely related species can persist. This non-random phylogenetic signal also implies a relationship between ecologically relevant characteristics and species relatedness.

  • 12.
    Riemann, Lasse
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Titelman, J.
    Båmstedt, U.
    Links between jellyfish and microbes in a jellyfish dominated fjord2006In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 325, p. 43-58Article in journal (Refereed)
  • 13. Rosenberg, R.
    et al.
    Dahl, E.
    Edler, L.
    Fyrberg, L.
    Granéli, Edna
    Department of Marine Ecology, University of Lund .
    Granéli, W.
    Hagström, Åke
    Department of Microbiology, University of Umeå .
    Lindahl, O.
    Matos, M.O.
    Pettersson, K.
    Sahlsten, E.
    Tiselius, P.
    Turk, V.
    Wikner, J.
    Pelagic nutrient and energy transfer during spring in the open and coastal Skagerrak.1990In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 61, no 3, p. 215-231Article in journal (Refereed)
  • 14. Sopanen, S
    et al.
    Koski, M
    Uronen, P
    Kuuppo, P
    Lehtinen, S
    Legrand, Catherine
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Tamminen, T
    Prymnesium parvum exotoxins affect the grazing and viability of the calanoid copepod Eurytemora affinis2008In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 361, p. 191-202Article in journal (Refereed)
    Abstract [en]

    The calanoid copepod Eurytemora affinis from the northern Baltic Sea was exposed to cell-free filtrates of the toxic haptophyte Prymnesium parvum as well as to cell mixtures of P. parvum and Rhodomonas salina. To test the effects of P. parvum exudates and allelopathy on selective grazers, copepods were incubated (1) in increasing concentrations of cell-free filtrates of P. parvum in the presence of good food (R, salina), (2) in 1:1 cell mixtures at 2 cell concentrations of P. parvum and R. salina and (3) in R. salina cell suspension, which was used as a control for good-quality food. P. parvum cultures were grown in nutrient-balanced (+NP) or limited (-N or -P) media to obtain different levels of toxicity. Survival, ingestion, faecal pellet production rates and egg production were measured over 3 d, together with measurements of P. parvum toxicity (hemolytic activity) (HA). Most of the copepods incubated in high-filtrate concentrations died or became severely impaired, although (HA) in filtrates was under the detection limit. Further, the ingestion and faecal pellet production rates were suppressed in the highest filtrate concentrations in nutrient-limited treatments. Higher cell density in cell mixtures resulted in significantly lower faecal pellet production, although survival remained high. Our results show that HA is not a good overall indicator of the total harmful effects of P. parvum on grazers. Besides monospecific P. parvum diets, filtrates and cell mixtures have negative effects on grazers, and these effects are stronger under nutrient-depleted conditions; however, the presence of good-quality food lowers harmful effects for copepods. The negative effects caused either by direct intoxication or by food limitation following from strong allelopathic effects of P. parvum on other components of nano- and microplankton suggest that P. parvum blooms have a realistic potential to be deleterious for copepod secondary production, irrespective of the presence of alternative food sources.

  • 15.
    Stewart, Joshua D.
    et al.
    Univ Calif San Diego, USA;Manta Trust, UK.
    Rohner, Christoph A.
    Marine Megafauna Fdn, Mozambique.
    Araujo, Gonzalo
    Large Marine Vertebrates Res Inst Philippines, Philippines.
    Avila, Jose
    Planeta Oceano, Peru.
    Fernando, Daniel
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Manta Trust, UK;Blue Resources Trust, Sri Lanka.
    Forsberg, Kerstin
    Planeta Oceano, Peru.
    Ponzo, Alessandro
    Large Marine Vertebrates Res Inst Philippines, Philippines.
    Rambahiniarison, Joshua M.
    Large Marine Vertebrates Res Inst Philippines, Philippines.
    Kurle, Carolyn M.
    Univ Calif San Diego, USA.
    Semmens, Brice X.
    Univ Calif San Diego, USA.
    Trophic overlap in mobulid rays: insights from stable isotope analysis2017In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 580, p. 131-151Article in journal (Refereed)
    Abstract [en]

    Mobulid rays, a group of closely related filter-feeders, are threatened globally by bycatch and targeted fisheries. Their habitat use and feeding ecology are not well studied, and most efforts have focused on temporally limited stomach content analysis or inferences from tagging data. Previous studies demonstrate a variety of different diving behaviors across species, which researchers have interpreted as evidence of disparate foraging strategies. However, few studies have examined feeding habitats and diets of multiple mobulid species from a single location, and it is unclear if the proposed differences in diving and inferred foraging behavior are examples of variability between species or regional adaptations to food availability. Here, we use stable isotope data from mobulids landed in fisheries to examine the feeding ecology of 5 species at 3 sites in the Indo-Pacific. We use Bayesian mixing models and analyses of isotopic niche areas to demonstrate dietary overlap between sympatric mobulid species at all of our study sites. We show the degree of overlap may be inversely related to productivity, which is contrary to prevailing theories of niche overlap. We use isotope data from 2 tissues to examine diet stability of Manta birostris and Mobula tarapacana in the Philippines. Finally, we observe a significant but weak relationship between body size and isotope values across species. Our findings highlight challenges to bycatch mitigation measures for mobulid species and may explain the multi-species mobulid bycatch that occurs in a variety of fisheries around the world.

  • 16.
    Stolte, Willem
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Balode, M
    Carlsson, Per
    Grzebyk, D
    Jansson, Sven
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Lips, I
    Panosso, Renata
    Ward, C J
    Granéli, Edna
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Stimulation of nitrogen-fixing cyanobacteria in a Baltic Sea plankton community by land-derived organic matter or iron addition2007In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 327, p. 71-82Article in journal (Refereed)
  • 17.
    Teira, E.
    et al.
    Univ Vigo, Spain.
    Hernandez-Ruiz, M.
    Univ Vigo, Spain.
    Barber-Lluch, E.
    Univ Vigo, Spain.
    Sobrino, C.
    Univ Vigo, Spain.
    Teixeira, I. G.
    Univ Vigo, Spain;CSIC, Inst Invest Marinas, Spain.
    Alvarez-Salgado, X. A.
    CSIC, Inst Invest Marinas, Spain.
    Nieto-Cid, M.
    CSIC, Inst Invest Marinas, Spain.
    Martínez-García, Sandra
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Univ Vigo, Spain.
    Figueiras, F. G.
    CSIC, Inst Invest Marinas, Spain.
    Fernandez, E.
    Univ Vigo, Spain.
    Bacterioplankton responses to riverine and atmospheric inputs in a coastal upwelling system (Ria de Vigo, NW Spain)2016In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 542, p. 39-50Article in journal (Refereed)
    Abstract [en]

    Anthropogenic pressures are changing the magnitude and nature of matter inputs into the ocean. The Ria de Vigo (NW Spain) is a highly productive and dynamic coastal system that is likely affected by such alterations. Previous nutrient-addition microcosm experiments conducted during contrasting hydrographic conditions suggested that heterotrophic bacteria are limited by organic carbon (C) and occasionally co-limited by inorganic nutrients in this coastal area. In order to assess short-term responses in biomass, production, and respiration of heterotrophic bacteria from the Ria de Vigo to increasing amounts of natural inputs of matter, we conducted 6 microcosm experiments, wherein surface seawater collected in spring, summer, and autumn was mixed with increasing amounts of dissolved natural matter concentrates from riverine and atmospheric origin. Simultaneous experiments with controlled inorganic and/or organic additions indicated that bacteria were co-limited by inorganic nutrients and C in spring and summer and primarily limited by C in autumn. Production responded more than biomass to increasing inputs of matter, whereas respiration did not change. The bacterial production response to increasing dissolved organic C load associated with riverine and atmospheric inputs was strongly related to the relative phosphorus (P) content of the dissolved matter concentrates. Our data suggest that bacterial production might decrease with the increase of P-deficient allochthonous matter inputs, which would have important biogeochemical consequences for C cycling in coastal areas.

  • 18.
    Teira, E.
    et al.
    University of Vigo, Spain.
    Hernando-Morales, V.
    University of Vigo, Spain.
    Fernández, A.
    University of Vigo, Spain.
    Martínez-García, Sandra
    University of Vigo, Spain.
    Álvarez-Salgado, X. A.
    Instituto de Investigacións Mariñas, Spain.
    Bode, A.
    Instituto Español de Oceanografía, Spain.
    Varela, M. M.
    Instituto Español de Oceanografía, Spain.
    Local differences in phytoplankton-bacterioplankton coupling in the coastal upwelling off Galicia (NW Spain)2015In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 528, p. 53-69Article in journal (Refereed)
    Abstract [en]

    We simultaneously studied microbial-mediated carbon fluxes at 2 contrasting sites within the coastal upwelling system off Galicia, near A Coruña and Vigo, Spain, over an annual cycle in order to compare the fraction of primary production released as dissolved organic carbon (DOC) and the degree of coupling between bacteria and phytoplankton. A significant fraction of primary production was released as DOC at both sites, averaging ∼30%. DOC release ac counted for, on average, 30% of the total bacterial carbon demand, which is indicative of a moderate trophic dependence of bacteria on phytoplankton in these coastal ecosystems. Nevertheless, differences in hydrographic conditions associated with stronger upwelling pulses off Vigo, and deeper upper mixed layers during the downwelling period off A Coruña, led to significant differences in phytoplankton dynamics and the subsequent direct coupling with heterotrophic bacteria. Strong direct coupling between phytoplankton extracellular release and bacterial production (BP) was found off Vigo, which could be related to the quality of the DOC produced by actively growing phytoplankton. By contrast, DOC release and BP rates were decoupled off A Coruña, likely due to unaccounted DOC associated with indirect trophic processes or to the low availability of freshly produced exudates associated with overflow or photoinhibition mechanisms.

  • 19. Titelman, J.
    et al.
    Riemann, Lasse
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Sørnes, T.
    Nilsen, T.
    Griekspoor, P.
    Båmstedt, U.
    Turnover of dead jellyfish: stimulation and retardation of microbial activity2006In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 325, p. 29-42Article in journal (Refereed)
  • 20. Wikner, J.
    et al.
    Hagström, Åke
    Department of Microbiology, University of Umeå.
    Evidence for a tightly coupled nanoplanktonic predator-prey link regulating the bacterivores in the marine environment1988In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 50, p. 137-145Article in journal (Refereed)
  • 21.
    Zweifel, Ulla Li
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Norrman, B.
    Hagström, Åke
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Consumption of dissolved organic carbon by marine bacteria and demand for inorganic nutrients.1993In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 101, p. 23-32Article in journal (Refereed)
1 - 21 of 21
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