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  • 1.
    Andersson, Agneta
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Brugel, Sonia
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Paczkowska, Joanna
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Rowe, Owen F.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF). Department of Food and Environmental Sciences, Division of Microbiology and Biotechnology, University of Helsinki, Helsinki, Finland.
    Figueroa, Daniela
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Kratzer, S.
    Legrand, C.
    Influence of allochthonous dissolved organic matter on pelagic basal production in a northerly estuary2018In: Estuarine, Coastal and Shelf Science, ISSN 0272-7714, E-ISSN 1096-0015, Vol. 204, p. 225-235Article in journal (Refereed)
    Abstract [en]

    Phytoplankton and heterotrophic bacteria are key groups at the base of aquatic food webs. In estuaries receiving riverine water with a high content of coloured allochthonous dissolved organic matter (ADOM), phytoplankton primary production may be reduced, while bacterial production is favoured. We tested this hypothesis by performing a field study in a northerly estuary receiving nutrient-poor, ADOM-rich riverine water, and analyzing results using multivariate statistics. Throughout the productive season, and especially during the spring river flush, the production and growth rate of heterotrophic bacteria were stimulated by the riverine inflow of dissolved organic carbon (DOC). In contrast, primary production and photosynthetic efficiency (i.e. phytoplankton growth rate) were negatively affected by DOC. Primary production related positively to phosphorus, which is the limiting nutrient in the area. In the upper estuary where DOC concentrations were the highest, the heterotrophic bacterial production constituted almost 100% of the basal production (sum of primary and bacterial production) during spring, while during summer the primary and bacterial production were approximately equal. Our study shows that riverine DOC had a strong negative influence on coastal phytoplankton production, likely due to light attenuation. On the other hand DOC showed a positive influence on bacterial production since it represents a supplementary food source. Thus, in boreal regions where climate change will cause increased river inflow to coastal waters, the balance between phytoplankton and bacterial production is likely to be changed, favouring bacteria. The pelagic food web structure and overall productivity will in turn be altered.

  • 2.
    Andersson, Agneta
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Höglander, Helena
    Karlsson, Chatarina
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Huseby, Siv
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Key role of phosphorus and nitrogen in regulating cyanobacterial community composition in the northern Baltic Sea2015In: Estuarine, Coastal and Shelf Science, ISSN 0272-7714, E-ISSN 1096-0015, Vol. 164, p. 161-171Article in journal (Refereed)
    Abstract [en]

    Despite cyanobacteria being a key phytoplankton group in the Baltic Sea, the factors governing their community structure are still poorly understood. Here, we studied the occurrence of the orders Chroococcales, Oscillatoriales and Nostocales, and potentially explanatory variables at five locations in the northern Baltic Sea from June–September, 1998–2012. Cyanobacteria constituted 1–36% of the total phytoplankton biomass along the north–south gradient. In the Bothnian Bay, Chroococcales and Oscillatoriales dominated the cyanobacterial community, whereas in the Bothnian Sea and northern Baltic Proper, Nostocales was the dominant group. The dominance of Chroococcales was coupled to low salinity and low total phosphorus, whereas Oscillatoriales correlated with high total nitrogen and low salinity. Nostocales correlated to high total phosphorus, inorganic phosphorus and salinity. Chroococcales showed an increase over time in the offshore Bothnian Bay, whereas Nostocales increased in the coastal Bothnian Sea and coastal Baltic Proper. The increase of Nostocales in the coastal Bothnian Sea was explained by a rise in total phosphorus and decrease in dissolved inorganic nitrogen compared to an increase of total nitrogen and phosphorus in the coastal Baltic Proper. No significant trends were observed in the cyanobacterial community in the offshore Bothnian Sea and the offshore northern Baltic Proper. We concluded that Chroococcales may be a useful indicator for increased phosphorus levels in waters with low phosphorus concentrations, whereas Nostocales could be used as a quality indicator for increasing phosphorus concentrations in waters with low inorganic N/P ratios (<20), such as in the coastal Bothnian Sea and Baltic Proper.

  • 3.
    Eriksson, Britas Klemens
    et al.
    Department of Plant Ecology, Uppsala University, Uppsala, Sweden.
    Bergström, Lena
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Local distribution patterns of macroalgae in relation to environmental variables in the northern Baltic Proper2005In: Estuarine, Coastal and Shelf Science, ISSN 0272-7714, E-ISSN 1096-0015, Vol. 62, no 1-2, p. 109-117Article in journal (Refereed)
    Abstract [en]

    The relationship between macroalgal assemblages and abiotic factors was quantified by gradient analyses in an area where long-term changes in macroalgal depth distributions have previously been documented. Biomass data from 4, 6, 8 and 10 m depth in an area of similar salinity (5) and substrate (rock) in the northern Baltic Proper was constrained by a set of environmental variables defining different aspects of abiotic control of species distributions (sediment cover, effective fetch, clarity index, the curvature and slope of the bottom, and direction of exposure) in multivariate analyses at different scales. Fucus vesiculosus dominated the biomass at 4, 6 and 8 m depth, andFurcellaria lumbricalis at 10 m. The applied models explained 30.7–53.3% of the total variance in community structure, and 49.3–60.9% when analysed separately for each depth. A separate analysis of species depth distributions demonstrated that effective fetch was most strongly related to upper limits of the algal belts, sediment cover to the lower limit and density of the F. vesiculosusbelt, and clarity index to the lower limits of F. vesiculosus, perennial red algae, and of the red algal and Sphacelaria spp. belts. The results show a strong correlation between environmental variables and vegetation structure even on a small, local scale in the northern Baltic Proper, indicating a high suitability of the phytobenthic zone for environmental monitoring. The results add to previous studies that show a strong importance of abiotic factors on large-scale variation in phytobentic community composition in the Baltic Sea.

  • 4. Karlsson, O Magnus
    et al.
    Malmaeus, J Mikael
    Josefsson, Sarah
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wiberg, Karin
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Håkanson, Lars
    Application of a mass-balance model to predict PCDD/F turnover in a Baltic coastal estuary2010In: Estuarine, Coastal and Shelf Science, ISSN 0272-7714, E-ISSN 1096-0015, Vol. 88, no 2, p. 209-18Article in journal (Refereed)
    Abstract [en]

    A dynamical, process-based mass-balance model was applied to quantify the transports of polychlorinated-p-dibenzodioxins and dibenzofurans (PCDD/Fs) to, within and from the Kallrigafjärden Bay, a coastal estuary in the Baltic Sea, and to predict the PCDD/F levels in the water and sediments of the bay. Before the modelling, a one-year sampling programme was implemented in 2007–2008 to measure the flows of PCDD/Fs in tributaries entering the system, the fluxes from the adjacent sea and the levels in water, sediment and fish within the estuary. The collected data set was used as input data to the model and for validation purposes.The model was originally developed and tested for suspended particulate matter and phosphorus in Baltic coastal areas. In this work, it was run monthly without any tuning of the original model variables. The simulation results compared favourably with the field measurements of levels of 15 PCDD/F congeners in the water and sediments of the bay. The dominating fluxes of PCDD/Fs were the exchange with the adjacent sea, followed by riverine input, atmospheric deposition and sediment burial.Although the sediment-water exchange was of minor importance for the overall mass-balance due to the rapid water turnover and limited areas favourable for the long-term deposition of fine sedimentary matter, sensitivity analyses indicated that the model’s predictive capability was improved with about 5% by taking the sediment burial and release into account.

  • 5.
    Panigrahi, Satya
    et al.
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF). Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Indira Gandhi Centre for Atomic Research.
    Nydahl, Anna
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF). Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Anton, Peter
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Wikner, Johan
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF). Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Strong seasonal effect of moderate experimental warming on plankton respiration in a temperate estuarine plankton community2013In: Estuarine, Coastal and Shelf Science, ISSN 0272-7714, E-ISSN 1096-0015, Vol. 136, p. 269-279Article in journal (Refereed)
    Abstract [en]

    Climate change projections forecast a 1.1-6.4 °C global increase in surface water temperature and a 3 °C increase for the Baltic Sea. This study examined the short-term interactive effects of a realistic future temperature increase (3 °C) on pelagic respiration and bacterioplankton growth and phytoplanktonphotosynthesis in situ. This study was undertaken throughout a full seasonal cycle in the northern Baltic Sea. We found marked positive short-term effects of temperature on plankton respiration but no significant effect on bacterioplankton growth or phytoplankton photosynthesis. Absolute respiration rates remained similar to other comparable environments at the in situ temperature. With the 3 °C temperature increase, respiration rates in situ increased up to 5-fold during the winter and 2-fold during the summer. A maximum seasonal Q10 value of 332 was observed for respiration during the cold winter months (twater z 0 C), and summer Q10 values were comparatively high (9.1). Q10 values exhibited a significant inverse relationship to water temperature during winter. Our results thereby suggest that plankton respiration in this coastal zone is more temperature sensitive than previously reported. In addition, field data indicated that plankton respiration switched from being temperature limited to being limited by dissolved organic carbon (DOC) after the simulated temperature increase. Assuming that our observations are relevant over longer time scales, climate change may worsen hypoxia, increase CO2 emissions and create a more heterotrophic food web in coastal zones with a high load of riverine DOC.

  • 6. Wiklund, A-K Eriksson
    et al.
    Andersson, Agneta
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Benthic competition and population dynamics of Monoporeia affinis and Marenzelleria sp in the northern Baltic Sea2014In: Estuarine, Coastal and Shelf Science, ISSN 0272-7714, E-ISSN 1096-0015, Vol. 144, p. 46-53Article in journal (Refereed)
    Abstract [en]

    During the last two decades major changes of the benthic fauna have occurred in the northern Baltic Sea, the Gulf of Bothnia. The native amphipod, Monoporeia affinis, has shown a large-scale abundance decrease, while polychaetes, Marenzelleria spp. have invaded the system. Marenzelleria co-exist with the native fauna in the southern Baltic Sea, but in the north the pelagic production might be too low to allow co-existence. Thus, M. affinis might have been out-competed by Marenzelleria in the Gulf of Bothnia. This hypothesis was tested in a competition experiment with a high and a low fresh phytoplankton food supply. When exposed to high food supply both species showed stable or increased biomass over the four week test period. In low food supply, however, M. affinis was found to have a competitive advantage. The experimental data were also related to Baltic Sea monitoring data on primary production, sedimentation and invertebrate abundances. Data from the northern Baltic Sea show that the dominance in the benthic community by M. affinis was replaced by Marenzelleria around 2001. The amphipod decrease might be explained by a marked decrease in primary production during this period. Combining monitoring and experimental data suggests that the invasion of Marenzelleria did not cause the decrease of M. affinis in the northern Baltic Sea; it rather took advantage of the density gap that had occurred. A shift may thus have been established in the Bothnian Sea benthic community. (C) 2014 Elsevier Ltd. All rights reserved.

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