| 1. |
- Wulff, Fredrik, et al.
(författare)
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Reduction of Baltic Sea Nutrient Inputs and Allocation of Abatement Costs Within the Baltic Sea Catchment
- 2014
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 43:1, s. 11-25
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Tidskriftsartikel (refereegranskat)abstract
- The Baltic Sea Action Plan (BSAP) requires tools to simulate effects and costs of various nutrient abatement strategies. Hierarchically connected databases and models of the entire catchment have been created to allow decision makers to view scenarios via the decision support system NEST. Increased intensity in agriculture in transient countries would result in increased nutrient loads to the Baltic Sea, particularly from Poland, the Baltic States, and Russia. Nutrient retentions are high, which means that the nutrient reduction goals of 135 000 tons N and 15 000 tons P, as formulated in the BSAP from 2007, correspond to a reduction in nutrient loadings to watersheds by 675 000 tons N and 158 000 tons P. A cost-minimization model was used to allocate nutrient reductions to measures and countries where the costs for reducing loads are low. The minimum annual cost to meet BSAP basin targets is estimated to 4.7 billion a,not sign.
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| 2. |
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| 3. |
- Andersen Borg, Marc, 1967-
(författare)
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Non-indigenous zooplankton : the role of predatory cladocerans and of copepods in trophic dynamics
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Human-mediated introductions of non-indigenous species now threaten to homogenize the biota of the Globe, causing huge economic and ecological damage. This thesis studies the ecological role of 3 invasive planktonic crustaceans, the omnivorous copepod Acartia tonsa (western Atlantic and Indo-Pacific) and the predatory cladocerans, Cercopagis pengoi (Ponto-Caspian) and Bythotrephes longimanus (Eurasian). B. longimanus invaded the North American Great Lakes in 1982, C. pengoi the Baltic in 1992 and the Great Lakes in 1999, while A. tonsa has an extensive invasion history that includes the Baltic.We review current knowledge on feeding biology of the predatory cladocerans. A study of stable C and N isotope ratios indicated mesozooplankton as the main food source of C. pengoi in the northern Baltic Sea proper, with young C. pengoi also eating microzooplankton, such as rotifers. Young-of-the-year herring did eat C. pengoi and herring trophic position shifted from 2.6 before the invasion to 3.4 after, indicating that C. pengoi had been “sandwiched” into the modified food web between mesozooplankton and fish.Salinity tolerance experiments on Acartia tonsa and co-occurring Acartia clausi showed the formers euryhaline character and high grazing potential. Energy partitioning between ingestion, production and respiration was rather constant over the tested salinity range of 2 to 33, with small differences in gross growth efficiency and cost of growth, but maximum ingestion at 10-20. Egg hatching in A. tonsa was only reduced at the lowest salinity. Extreme changes in salinity were needed to cause significant mortality of A. tonsa in the field, but its feeding activity could be severely reduced by salinity changes likely to occur in estuaries. A study of a hypertrophic estuary showed that A. tonsa can sustain a population despite very high mortality rates, caused by predation, high pH and low oxygen, helping explain the success of A. tonsa as an invader of estuaries.
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| 4. |
- Artioli, Yuri, et al.
(författare)
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Nutrient budgets for European seas: A measure of the effectiveness of nutrient reduction policies.
- 2008
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Ingår i: Marine Pollution Bulletin. - : Elsevier BV. - 0025-326X .- 1879-3363. ; 56:9, s. 1609-1617
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Tidskriftsartikel (refereegranskat)abstract
- Socio-economic development in Europe has exerted increasing pressure on the marine environment. Eutrophication, caused by nutrient enrichment, is evident in regions of all European seas. Its severity varies but has, in places, adversely impacted socio-economic activities. This paper aims to evaluate the effectiveness of recently adopted policies to reduce anthropogenic nutrient inputs to European seas. Nitrogen and phosphorus budgets were constructed for three different periods (prior to severe eutrophication, during severe eutrophication and contemporary) to capture changes in the relative importance of different nutrient sources in four European seas suffering from eutrophication (Baltic Proper, coastal North Sea, Northern Adriatic and North-Western Black Sea Shelf). Policy success is evident for point sources, notably for P in the Baltic and North Seas, but reduction of diffuse sources has been more problematic.
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| 5. |
- Conley, Daniel, et al.
(författare)
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Hypoxia-Related Processes in the Baltic Sea
- 2009
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 43:10, s. 3412-3420
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Tidskriftsartikel (refereegranskat)abstract
- Hypoxia, a growing worldwide problem, has been intermittently present in the modern Baltic Sea since its formation ca. 8000 cal. yr BP. However, both the spatial extent and intensity of hypoxia have increased with anthropogenic eutrophication due to nutrient inputs. Physical processes, which control stratification and the renewal of oxygen in bottom waters, are important constraints on the formation and maintenance of hypoxia. Climate controlled inflows of saline water from the North Sea through the Danish Straits is a critical controlling factor governing the spatial extent and duration of hypoxia. Hypoxia regulates the biogeochemical cycles of both phosphorus (P) and nitrogen (N) in the water column and sediments. Significant amounts of P are currently released from sediments, an order of magnitude larger than anthropogenic inputs. The Baltic Sea is unique for coastal marine ecosystems experiencing N losses in hypoxic waters below the halocline. Although benthic communities in the Baltic Sea are naturally constrained by salinity gradients, hypoxia has resulted in habitat loss over vast areas and the elimination of benthic fauna, and has severely disrupted benthic food webs. Nutrient load reductions are needed to reduce the extent, severity, and effects of hypoxia.
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| 6. |
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| 7. |
- Eriksson Hägg, Hanna, et al.
(författare)
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Scenario Analysis on Protein Consumption and Climate Change Effects on Riverine N Export to the Baltic Sea
- 2010
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 44:7, s. 2379-2385
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Tidskriftsartikel (refereegranskat)abstract
- This paper evaluates possible future nitrogen loadings from 105 catchments surrounding the Baltic Sea. Multiple regressions are used to model total nitrogen (TN) flux as a function of specific runoff (0), atmospheric nitrogen deposition, and primary emissions (PE) from humans and livestock. On average cattle contributed with 63%, humans with 20%, and pigs with 17% of the total nitrogen PE to land. Compared to the reference period (1992-1996) we then evaluated two types of scenarios for year 2070. i) An increased protein consumption scenario that led to 16% to 39% increased mean TN flux (kg per km(-2)). ii) Four climate scenarios addressing effects of changes in river discharge. These scenarios showed increased mean TN flux from the northern catchments draining into the Gulf of Bothnia (34%) and the Gulfs of Finland and Riga (14%), while the mean TN flux decreased (-27%) for catchments draining to the Baltic Proper. However, the net effect of the scenarios showed a possible increase in TN flux ranging from 3-72%. Overall an increased demand for animal protein will be instrumental for the Baltic Sea ecosystem and may be a major holdback to fulfill the environmental goals of the Baltic Sea Action Plan.
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| 8. |
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| 9. |
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| 10. |
- Humborg, Christoph, et al.
(författare)
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Riverine transport of biogenic elements to the Baltic Sea – past and possible future perspectives
- 2007
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Ingår i: Hydrology and Earth System Sciences. - 1027-5606 .- 1607-7938. ; 11:5, s. 1593-1607
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Tidskriftsartikel (refereegranskat)abstract
- The paper reviews critical processes for the land-sea fluxes of biogenic elements (C, N, P, Si) in the Baltic Sea catchment and discusses possible future scenarios as a consequence of improved sewage treatment, agricultural practices and increased hydropower demand (for N, P and Si) and of global warming, i.e., changes in hydrological patterns (for C). These most significant drivers will not only change the total amount of nutrient inputs and fluxes of organic and inorganic forms of carbon to the Baltic Sea, their ratio (C:N:P:Si) will alter as well with consequences for phytoplankton species composition in the Baltic Sea. In summary, we propose that N fluxes may increase due to higher livestock densities in those countries recently acceded to the EU, whereas P and Si fluxes may decrease due to an improved sewage treatment in these new EU member states and with further damming and still eutrophic states of many lakes in the entire Baltic Sea catchment. This might eventually decrease cyanobacteria blooms in the Baltic but increase the potential for other nuisance blooms. Dinoflagellates could eventually substitute diatoms that even today grow below their optimal growth conditions due to low Si concentrations in some regions of the Baltic Sea. C fluxes will probably increase from the boreal part of the Baltic Sea catchment due to the expected higher temperatures and heavier rainfall. However, it is not clear whether dissolved organic carbon and alkalinity, which have opposite feedbacks to global warming, will increase in similar amounts, because the spring flow peak will be smoothed out in time due to higher temperatures that cause less snow cover and deeper soil infiltration.
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| 11. |
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| 12. |
- McQuatters-Gollop, Abigail, et al.
(författare)
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How well do ecosystem indicators communicate the effects of anthropogenic eutrophication?
- 2009
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Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 82, s. 583-596
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Tidskriftsartikel (refereegranskat)abstract
- Anthropogenic eutrophication affects the Mediterranean, Black, North and Baltic Seas to various extents. Responses to nutrient loading and methods of monitoring relevant indicators vary regionally, hindering interpretation of ecosystem state changes and preventing a straightforward pan-European assessment of eutrophication symptoms. Here we summarize responses to nutrient enrichment in Europe's seas, comparing existing time-series of selected pelagic (phytoplankton biomass and community composition, turbidity, N:P ratio) and benthic (macro flora and faunal communities, bottom oxygen condition) indicators based on their effectiveness in assessing eutrophication effects. Our results suggest that the Black Sea and Northern Adriatic appear to be recovering from eutrophication due to economic reorganization in the Black Sea catchment and nutrient abatement measures in the case of the Northern Adriatic. The Baltic is most strongly impacted by eutrophication due to its limited exchange and the prevalence of nutrient recycling. Eutrophication in the North Sea is primarily a coastal problem, but may be exacerbated by climatic changes. Indicator interpretation is strongly dependent on sea-specific knowledge of ecosystem characteristics, and no single indicator can be employed to adequately compare eutrophication state between European seas. Communicating eutrophication-related information to policy-makers could be facilitated through the use of consistent indicator selection and monitoring methodologies across European seas. This work is discussed in the context of the European Commission's recently published Marine Strategy Directive.
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| 13. |
- Orädd, Fredrik, et al.
(författare)
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Tracking the ATP-binding response in adenylate kinase in real time
- 2021
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Ingår i: Science Advances. - : American Association for the Advancement of Science. - 2375-2548. ; 7:47
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Tidskriftsartikel (refereegranskat)abstract
- The biological function of proteins is critically dependent on dynamics inherent to the native structure. Such structural dynamics obey a predefined order and temporal timing to execute the specific reaction. Determination of the cooperativity of key structural rearrangements requires monitoring protein reactions in real time. In this work, we used time-resolved x-ray solution scattering (TR-XSS) to visualize structural changes in the Escherichia coli adenylate kinase (AdK) enzyme upon laser-induced activation of a protected ATP substrate. A 4.3-ms transient intermediate showed partial closing of both the ATP- and AMP-binding domains, which indicates a cooperative closing mechanism. The ATP-binding domain also showed local unfolding and breaking of an Arg131-Asp146 salt bridge. Nuclear magnetic resonance spectroscopy data identified similar unfolding in an Arg131Ala AdK mutant, which refolded in a closed, substrate-binding conformation. The observed structural dynamics agree with a “cracking mechanism” proposed to underlie global structural transformation, such as allostery, in proteins.
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| 14. |
- Pechsiri, Joseph
(författare)
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Nutrient Recovery as an Added Benefit to Harvests of Photosynthetic Marine Biomass : A Holistic Systems Perspective on Harvesting Marine Microalgae, Cyanobacteria, and Macroalgae
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- As a result of increasing environmental burdens from anthropogenic activities andresource scarcity, interest for the development of solutions utilizing photosyntheticmarine biomass has also been increasing in both academia and industries. Medium tolarge scale production and harvest of photosynthetic marine biomass have beenpracticed to achieve numerous services, including improving tourism industries,production of biofuels, and production of food/feed. However, few studies haveevaluated the potential for nutrient recovery as an added benefit to the aforementionedservices and the potential environmental burdens of such solutions from a holisticsystems perspective. This thesis, therefore, sought to determine the nutrient recoverypotential of harvesting photosynthetic marine biomass at industrial scales whileassessing the environmental burdens from a holistic systems perspective. Techniquesinvolving life cycle inventory and analysis, input-output analysis, growth modellingand experimentation, energy analysis, and assessment of greenhouse gas emissionsfrom a life cycle perspective were used to assess the potential environmental burdensof large scale harvest of photosynthetic marine biomass.This study employed five real world case studies of five different photosynthetic marinebiomass species at various geographical locations across the globe. Each case wasassessed to determine the potential to recover nutrients while evaluating the potentialenvironmental burdens from an energy and greenhouse gas perspective. Each casecontains unique specific details and therefore methods applied were case specific.Results showed that nutrient recovery potential existed in most cases with the exceptionof one case. Cases evaluated for their potential environmental burdens showed thatlarge scale harvest of photosynthetic marine biomass is resource intensive regardless ofspecies but showed mixed results from an energy perspective. The key findings of thisthesis were that a) the potential for nutrient recovery was estimated in both large scalecultivation and large scale wild harvest of photosynthetic marine biomass, b) from anenergy and biomass harvesting perspective, the viability of industrial harvests ofphotosynthetic marine biomass were found for both large scale cultivations and wildharvesting of biomass blooms, and c) scale of operations is an important factor towardsevaluating the environmental performance of photosynthetic marine biomassproduction systems.
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| 15. |
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| 16. |
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| 17. |
- Rydin, Emil, et al.
(författare)
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Remediation of a eutrophic bay in the Baltic Sea
- 2017
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 51:8, s. 4559-4566
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Tidskriftsartikel (refereegranskat)abstract
- Eutrophication of coastal ecosystems is a global problem that often results in bottom water oxygen deficiency and in turn promotes sediment phosphorus (P) release (A). In order to increase sediment P retention, we injected dissolved aluminum into the anoxic sediment of a eutrophic semienclosed bay in the Baltic Sea, thereby inhibiting P recycling and further eutrophication (B). The P concentration in the bay remained at half, as did phytoplankton biomass (C), compared to pretreatment conditions and compared to the reference bay. Four years after treatment the water column transparency was increased, allowing submerged vegetation to penetrate deeper, and the habitat suitable for fish and benthic fauna had expanded (D). The lowered P concentration in the bay decreased the P export to the surrounding archipelago. This is the first full-scale marine remediation project using a geo-engineering method that demonstrates a quick recovery. For successful remediation in coastal areas, permanent binding of mobile P in anoxic sediments may be needed together with measures in the catchment area to obtain faster recovery of eutrophicated marine ecosystems.
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| 18. |
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| 19. |
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| 20. |
- Savchuk, Oleg P., et al.
(författare)
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External nutrient loads to the Baltic Sea, 1970-2006
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Any research related to nutrient biogeochemistry of the Baltic Sea, especially studies of eutrophication requires knowledge of the long-term dynamics of external nutrient inputs. Information accumulated in the HELCOM’s pollution load compilations is too aggregated and, until recently, covered only specific years. On the other hand, national datasets with higher resolutions are often difficult to access. Therefore, over the years considerable efforts have been put into a compilation of consistent estimates of nutrient input to the entire Baltic Sea.Excluding exchange with the Skagerrak from this report, the external nutrient input is considered here as consisting of three component parts: waterborne land loads, direct point sources at the coasts, and atmospheric depositions.The present reconstruction of time series of these three components is based on three major sources. The compilation of the land loads database has started within the project “Large-scale Environmental Effects and Ecological Processes in the Baltic Sea, 1990-1995” (Wulff et al., 2001c), continued during the MARE (“Marine Research on Eutrophication, 1999-2006”) project (Wulff et al., 2001a, Eriksson Hägg et al., 2010), and was most recently updated and expanded in connection with the latest HELCOM’s activities on the pollution load compilation (HELCOM, 2011) and the revision of the Baltic Sea Action Plan (BSAP, Wulff et al., 2009). However, there is an important difference between information contained in the HELCOM publications and the data presented here.By its very international nature HELCOM has to deal with whatever data are officially provided by the contracting parties, ending up with certain gaps and inconsistencies in the data sets (e.g. see discussion in HELCOM, 2011). On the other hand, considering eutrophication as an imbalance in the large-scale nutrient cycles, whereby more nutrients come into the system than leave it (e.g. Savchuk and Wulff, 2009 and references therein), we need to know the total amounts of external input as close to the reality as possible. Therefore, in our reconstructions we have been trying to both fill such gaps in and correct possible sources of inconsistencies. The reconstructed data sets have extensively been used by ourselves for various nutrient budget estimates (e.g. Wulff et al., 2001b, Savchuk, 2005) and as the boundary conditions for biogeochemical models (e.g. Savchuk and Wulff, 2007, 2009) including development of the eutrophication segment of BSAP (Wulff, 2007), as well as by many researchers around the Baltic Sea, for instance, within several projects of the BONUS+ research programme (e.g.Eilola et al., 2011; Eriksson Hägg et al., 2011; Meier et al., 2011).The implemented nutrient inputs have naturally been described in these publications, but briefly. In order to facilitate afurther distribution of reconstructed inputs and their usage, here we describe the process of reconstruction in more detail and make available the full data sets in digital form.The data used for the reconstruction have kindly been provided by several institutions and agencies around the Baltic Sea (see below) as well as directly by HELCOM during preparation of PLC-4 and PLC-5 (see HELCOM, 2004, 2011). Since not all data providershad given the permission to distribute the original raw measurements, we have here 3 aggregated all the inputs according to the spatial segmentation of the Baltic Sea (Fig.1) currently implemented in the biogeochemical model BALTSEM (BAltic sea Long-Term large Scale Eutrophication Model). Note also that some part of riverine inputs is available in a decision support system Baltic Nest with a much higher spatial resolution, as is further explained below.
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| 21. |
- Savchuk, Oleg P., et al.
(författare)
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Long-term modeling of large-scale nutrient cycles in the entire Baltic Sea
- 2009
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Ingår i: Hydrobiologia. - : Springer Science and Business Media LLC. - 0018-8158 .- 1573-5117. ; 629, s. 209-224
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Tidskriftsartikel (refereegranskat)abstract
- Management of eutrophication in marine ecosystems requires a good understanding of nutrient cycles at the appropriate spatial and temporal scales. Here, it is shown that the biogeochemical processes controlling large-scale eutrophication of the Baltic Sea can be described with a fairly aggregated model: simple as necessary Baltic long-term large scale (SANBALTS). This model simulates the dynamics of nitrogen, phosphorus, and silica driven by the external inputs, the major physical transports, and the internal biogeochemical fluxes within the seven major sub-basins. In a long-term hindcast (1970–2003), the model outputs reasonably matched observed concentrations and fluxes. The model is also tested in a scenario where nutrient inputs are reduced to levels that existed over 100 years ago. The simulated response of the Baltic Sea trophic state to this very large reduction is verified by a similar simulation made with a much more complex process-oriented model. Both models indicate that after initial, rather rapid changes the system goes into much slower evolution, and nutrient cycles would not become balanced even after 130 years.
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| 22. |
- Savchuk, Oleg P., et al.
(författare)
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The Baltic Sea a century ago – a reconstruction from model simulations, verified by observations.
- 2008
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Ingår i: Journal of Marine Systems. - : Elsevier BV. - 0924-7963. ; 74, s. 485-494
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Tidskriftsartikel (refereegranskat)abstract
- “Pre-industrial” trophic conditions in the Baltic Sea were simulated with SANBALTS (Simple As Necessary BAltic Long-Term large Scale) model. External nutrient inputs to the major basins of the Baltic Sea a century ago were reconstructed from various literature and data sources. The reconstructed input of total nitrogen was less than a half and that of total phosphorus was about a third of their contemporary values. The simulated “pre-industrial” conditions are validated by comparison to actual historical data on the water transparency, oxygen concentration, primary production, and net sediment accumulation. The “pre-industrial” trophic state could have been more phosphorus limited than today because simulated basin-wide annual averages of dissolved inorganic phosphorus concentrations of 0.06–0.3 µM P are about 40–80% of their present day values, while dissolved inorganic nitrogen concentrations of 2–4 µM N are almost the same as today or even slightly higher.
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| 23. |
- Sundbäck, Kristina, 1949, et al.
(författare)
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Benthic nitrogen fluxes along a depth gradient in a microtidal fjord: The role of denitrification and microphytobenthos
- 2004
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Ingår i: Limnology and Oceanography. - 0024-3590. ; 49:4, s. 1095-1107
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Tidskriftsartikel (refereegranskat)abstract
- In littoral sediments, microphytobenthic (MPB) nitrogen assimilation often exceeds nitrogen removal by denitrification, partly because MPB activity suppresses denitrification. Little is known about the balance between these two processes at sublittoral depths. Benthic pigment composition, light and dark oxygen, and nutrient fluxes (NO3-, NH4+, dissolved organic nitrogen (DON), PO43-, Si(OH)(4)), as well as denitrification were measured between 1 and 15 m in depth in Gullmar Fjord (Skagerrak) in spring and autumn. The hypothesis was that the assimilation/denitrification ratio would decrease with depth, along with decreasing MPB activity caused by light limitation. MPB photosynthesis occurred along the entire depth gradient, although sediments were net autotrophic only above 5 m. Inorganic nitrogen (DIN) (and silica) flux changed along the depth gradient, the general pattern being sediment uptake at less than or equal to5 m and efflux at greater than or equal to10 m depth. DON flux (similar to50% of total dissolved nitrogen flux) showed a less clear pattern. Two trends regarding DIN fluxes and denitrification-significant light effects and negative correlations with gross primary productivity-showed that MPB activity influenced nitrogen (N) turnover. Although denitrification increased with depth, rates remained low (<0.4 mmol N m(-2) d(-1)), and MPB assimilation (0.2-3.6 mmol N m(-2) d(-1)) exceeded or equaled denitrification. MPB incorporated similar to35% of the remineralized N along the depth gradient, whereas denitrification removed similar to20%. Thus, the influence of MPB on benthic nitrogen turnover, denitrification included, extends to sublittoral depths. Further, denitrification does not necessarily remove more N in the deeper, heterotrophic part of the photic zone, compared to the littoral, autotrophic zone.
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| 24. |
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| 25. |
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| 26. |
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| 27. |
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| 28. |
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| 29. |
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| 30. |
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| 31. |
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| 32. |
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| 33. |
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| 34. |
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| 35. |
- Wulff, Fredrik, et al.
(författare)
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Nest – a decision support systemfor management of the Baltic Sea : A user manual
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The decision support system Nest was initially developed within the MISTRA-funded MARE research program, which was completed in 2007. Nest was then successfully used for the development of the eutrophication segment of the HELCOM Baltic Sea Action Plan, where nutrient load reductions needed to reach a healthy Baltic Sea were calculated, as were the allocations between countries. Nest is also used in many research programs.The maintenance and further development of Nest has continued within the Baltic Nest Institute. The Nest system links the entire Baltic Sea region, from watershed to offshore ecosystems, through data and models. It is available online, free of charge, and can be run in both expert and standard mode. The main target groups of the Nest system are decision-makers and scientists in the Baltic region interacting with the Helsinki Commission (HELCOM), as well as those working on the implementation of the EU Water Framework Directive and Marine Strategy Framework Directive.We also hope that it can be useful for students interested in learning more about the Baltic Sea. The different components describe forcing by nutrient inputs and characteristics of the drainage and sea basins. The marine models describe the physics and biogeochemistry of the Sea, as well as of its food webs (to the levels of man and seals), and are used in scenarios of how fisheries, eutrophication, and climate change affect this unique ecosystem.Finally, the strong interdependence of the countries around the Baltic is illustrated when the costs for reducing nutrient load, with or without cooperation, are calculated. This manual is by no means the final version: it will be continuously improved and modified, both as a result of user inputs and when components of Nest are modified. Nest has been designed as a web distributed system and to use it you need access to the Internet; some components are installed on your (client) computer, others are installed on the servers that you communicate with. Experts continuously update the components of Nest. Each time you start the program, your client software is checked and updated if a new version is available. This procedure ensures that you always use the most recent version of Nest.
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| 36. |
- Wulff, Fredrik, et al.
(författare)
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Nitrogen versus phosphorus limitation in a subtropical coastal embayment (Moreton Bay; Australia) : Implications for management
- 2011
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Ingår i: Ecological Modelling. - : Elsevier BV. - 0304-3800 .- 1872-7026. ; 222:1, s. 120-130
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Tidskriftsartikel (refereegranskat)abstract
- An approach combining nutrient budgets, dynamic modelling, and field observations of phytoplankton and nitrogen (N(2))-fixing Lyngbya majuscula following changes in wastewater N loads, was used to demonstrate that Moreton Bay is potentially phosphorus (P) limited. Modelling and nutrient budgeting shows that benthic N-fixation loads are high, allowing the system to overcome any potential N-limitation. Phytoplankton biomass has shown little change from 1991 to 2006 in the sections of Moreton Bay most impacted by wastewater effluents, despite a large reduction in wastewater N loads from 2000 to 2002. This is consistent with modelling that also showed no reduction in primary productivity associated with reduced N loads. Most importantly, there have been rapid increases in the occurrence of N-fixing L majuscula in Moreton Bay as wastewater P loads have increased relative to wastewater N loads. This is also consistent with modelling. This work supports the premise that there may be fundamental differences in nutrient limitation of primary production between subtropical and temperate coastal systems due to differences in the importance of internal nitrogen sources and sinks (N-fixation and denitrification). These differences need to be recognised for optimum management of coastal systems.
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| 37. |
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| 38. |
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| 39. |
- Wulff, Fredrik, et al.
(författare)
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Revision of the country allocation of nutrient reductions in the Baltic Sea Action Plan. Section A: Hydrological adjusted riverine loads and atmospheric loads from different countries averaged for 2000 - 2006 : Technical Report No. 1
- 2009
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- HELCOM has asked BNI to revise the country-wise nutrient allocations of the Baltic Sea Action Plan using the new data available on atmospheric loads (EMEP) and more recent calculations on loads from the drainage basins (PLC5).We are here reporting the most recent and updated data on loads from the drainage basins, averaged for 2000-2006 and 1997-2003, based on data supplied by the HELCOM member states for the preparation of the Fifth Pollution Load compilation (PLC5).The nutrient load data for 1997-2003, the period used for the original country allocation sceme of BSAP as signed in Krakow 2007, have been updated as well as new estimates for 2000-2006. The latter period has been suggested by HELOM as the foundation for an updated BSAP.However, these periods include several very dry or wet years. Drastic changes of the inputs seen in these data may therefore partly reflect these hydrological variations rather thanreal changes of loads due to efforts by the countries to reduce emissions. We therefore found it necessary to normalise these values, taking into account variations in riverine flows.Russian data were found to be very incomplete and we therefore had to re-evaluate and compute new estimates, beyond those available in the PLC5 database.We also report recent calculations on atmospheric loads to the different Baltic sub basins, averaged for 1997-2003 and 2000-2006, made available on the Internet by EMEP and integrated into NEST. The loads are now source allocated to the different HELCOM countries and other sources in order to be used in the revision of the country allocation scheme of BSAP.
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| 40. |
- Österblom, Henrik, et al.
(författare)
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Human-induced trophic cascades and ecological regime shifts in the Baltic Sea
- 2007
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Ingår i: Ecosystems (New York. Print). - : Springer Science and Business Media LLC. - 1432-9840 .- 1435-0629. ; 10:6, s. 877-889
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Tidskriftsartikel (refereegranskat)abstract
- The ecosystems of coastal and enclosed seas are under increasing anthropogenic pressure worldwide, with Chesapeake Bay, the Gulf of Mexico and the Black and Baltic Seas as well known examples. We use an ecosystem model (Ecopath with Ecosim, EwE) to show that reduced top-down control (seal predation) and increased bottom-up forcing (eutrophication) can largely explain the historical dynamics of the main fish stocks (cod, herring and sprat) in the Baltic Sea between 1900 and 1980. Based on these results and the historical fish stock development we identify two major ecological transitions. A shift from seal to cod domination was caused by a virtual elimination of marine mammals followed by a shift from an oligotrophic to a eutrophic state. A third shift from cod to clupeid domination in the late 1980s has previously been explained by overfishing of cod and climatic changes. We propose that the shift from an oligotrophic to a eutrophic state represents a true regime shift with a stabilizing mechanism for a hysteresis phenomenon. There are also mechanisms that could stabilize the shift from a cod to clupeid dominated ecosystem, but there are no indications that the ecosystem has been pushed that far yet. We argue that the shifts in the Baltic Sea are a consequence of human impacts, although variations in climate may have influenced their timing, magnitude and persistence.
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