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  • 1.
    Palomino-Ángel, Sebastián
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Universidad de Medellín, Colombia.
    Anaya-Acevedo, Jesús A.
    Simard, Marc
    Liao, Tien-Hao
    Jaramillo, Fernando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. Stockholms universitet, Naturvetenskapliga fakulteten, Stockholm Resilience Centre.
    Analysis of Floodplain Dynamics in the Atrato River Colombia Using SAR Interferometry2019Ingår i: Water, ISSN 2073-4441, E-ISSN 2073-4441, Vol. 11, nr 5, artikel-id 875Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Floodplain water flows have large volumetric flowrates and high complexity in space and time that are difficult to understand using water level gauges. We here analyze the spatial and temporal fluctuations of surface water flows in the floodplain of the Atrato River, Colombia, in order to evaluate their hydrological connectivity. The basin is one of the rainiest areas of the world with wetland ecosystems threatened by the expansion of agriculture and mining activities. We used 16 Differential Interferometric Synthetic Aperture Radars (DInSAR) phase observations from the ALOS-PALSAR L-band instrument acquired between 2008-2010 to characterize the flow of surface water. We were able to observe water level change in vegetated wetland areas and identify flooding patterns. In the lower basin, flow patterns are conditioned by fluctuations in the levels of the main river channel, whereas in the middle basin, topography and superficial channels strongly influence the flow and connectivity. We found that the variations in water level in a station on the main channel 87 km upstream explained more than 56% of the variations in water level in the floodplain. This result shows that, despite current expansion of agriculture and mining activities, there remain significant hydrological connectivity between wetlands and the Atrato River. This study demonstrates the use of DInSAR for a spatially comprehensive monitoring of the Atrato River basin hydrology. For the first time, we identified the spatiotemporal patterns of surface water flow of the region. We recommend these observations serve as a baseline to monitor the potential impact of ongoing human activities on surface water flows across the Atrato River basin.

  • 2. Meier, H. E. Markus
    et al.
    Edman, Moa
    Eilola, Kari
    Placke, Manja
    Neumann, Thomas
    Andersson, Helen C.
    Brunnabend, Sandra-Esther
    Dieterich, Christian
    Frauen, Claudia
    Friedland, Rene
    Gröger, Matthias
    Gustafsson, Bo G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland.
    Gustafsson, Erik
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Isaev, Alexey
    Kniebusch, Madline
    Kuznetsov, Ivan
    Müller-Karulis, Bärbel
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Naumann, Michael
    Omstedt, Anders
    Ryabchenko, Vladimir
    Saraiva, Sofia
    Savchuk, Oleg P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Assessment of Uncertainties in Scenario Simulations of Biogeochemical Cycles in the Baltic Sea2019Ingår i: Frontiers in Marine Science, E-ISSN 2296-7745, Vol. 6, artikel-id 46Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Following earlier regional assessment studies, such as the Assessment of Climate Change for the Baltic Sea Basin and the North Sea Region Climate Change Assessment, knowledge acquired from available literature about future scenario simulations of biogeochemical cycles in the Baltic Sea and their uncertainties is assessed. The identification and reduction of uncertainties of scenario simulations are issues for marine management. For instance, it is important to know whether nutrient load abatement will meet its objectives of restored water quality status in future climate or whether additional measures are required. However, uncertainties are large and their sources need to be understood to draw conclusions about the effectiveness of measures. The assessment of sources of uncertainties in projections of biogeochemical cycles based on authors' own expert judgment suggests that the biggest uncertainties are caused by (1) unknown current and future bioavailable nutrient loads from land and atmosphere, (2) the experimental setup (including the spin up strategy), (3) differences between the projections of global and regional climate models, in particular, with respect to the global mean sea level rise and regional water cycle, (4) differing model-specific responses of the simulated biogeochemical cycles to long-term changes in external nutrient loads and climate of the Baltic Sea region, and (5) unknown future greenhouse gas emissions. Regular assessments of the models' skill (or quality compared to observations) for the Baltic Sea region and the spread in scenario simulations (differences among projected changes) as well as improvement of dynamical downscaling methods are recommended.

  • 3.
    Jakobsson, Martin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    Stranne, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    O'Regan, Matt
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    Greenwood, Sarah L.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    Gustafsson, Bo
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Humborg, Christoph
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Weidner, Elizabeth
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper. University of New Hampshire, USA.
    Bathymetric properties of the Baltic Sea2019Ingår i: Ocean Science, ISSN 1812-0784, E-ISSN 1812-0792, Vol. 15, nr 4, s. 905-924Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Baltic Sea bathymetric properties are analysed here using the newly released digital bathymetric model (DBM) by the European Marine Observation and Data Network (EMODnet). The analyses include hypsometry, volume, descriptive depth statistics, and kilometre-scale seafloor ruggedness, i.e. terrain heterogeneity, for the Baltic Sea as a whole as well as for 17 sub-basins defined by the Baltic Marine Environment Protection Commission (HELCOM). We compare the new EMODnet DBM with IOWTOPO the previously most widely used DBM of the Baltic Se aproduced by the Leibniz-Institut fur Ostseeforschung Warnemiinde (IOW), which has served as the primary gridded bathymetric resource in physical and environmental studies for nearly two decades. The area of deep water exchange between the Bothnian Sea and the Northern Baltic Proper across the Aland Sea is specifically analysed in terms of depths and locations of critical bathymetric sills. The EMODnet DBM provides a bathymetric sill depth of 88 m at the northern side of the Aland Sea and 60 m at the southern side, differing from previously identified sill depths of 100 and 70 m, respectively. High-resolution multibeam bathymetry acquired from this deep water exchange path, where vigorous bottom currents interacted with the seafloor, allows us to assess what presently available DBMs are missing in terms of physical characterization of the seafloor. Our study highlights the need for continued work towards complete high-resolution mapping of the Baltic Sea seafloor.

  • 4.
    Ehrnsten, Eva
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland.
    Norkko, Alf
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland.
    Timmermann, Karen
    Gustafsson, Bo G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland.
    Benthic-pelagic coupling in coastal seas - Modelling macrofaunal biomass and carbon processing in response to organic matter supply2019Ingår i: Journal of Marine Systems, ISSN 0924-7963, E-ISSN 1879-1573, Vol. 196, s. 36-47Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Benthic macrofauna is an important component linking pelagic and benthic ecosystems, especially in productive coastal areas. Through their metabolism and behaviour, benthic animals affect biogeochemical fluxes between the sediment and water column. Mechanistic models that quantify these benthic-pelagic links are imperative to understand the functioning of coastal ecosystems. In this study, we develop a dynamic model of benthic macrofauna to quantify the relationship between organic matter input and benthic macrofaunal biomass in the coastal zone. The model simulates the carbon dynamics of three functional groups of benthic macrofauna and their sediment food sources and is forced by a hydrodynamic-biogeochemical model simulating pelagic physical and biological dynamics. The model reproduces measured time-series of macrofaunal biomass from two coastal sites with contrasting sedimentation in the Baltic Sea in 1993-2005 with comparatively high accuracy, including a major increase at one of the sites dominated by the bivalve Limecola (Macoma) balthica. This shift in community composition suggests altered pathways of organic matter degradation: 39% of simulated sedimentation was mineralised by macrofauna in 2005 compared to 10% in 1995. From the early 2000s onward macrofaunal biomass seems to be food-limited, as ca 80% of organic carbon sedimentation was processed by the deposit-feeding macrofauna at both sites. This model is a first step to help quantify the role of macrofauna in marine coastal ecosystem functioning and biogeochemical cycles and build predictive capacity of the effects of anthropogenic stressors, such as eutrophication and climate change, on coastal ecosystems.

  • 5. Jansson, Torbjörn
    et al.
    Andersen, Hans Estrup
    Hasler, Berit
    Höglind, Lisa
    Gustafsson, Bo G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland.
    Can investments in manure technology reduce nutrient leakage to the Baltic Sea?2019Ingår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 48, nr 11, s. 1264-1277Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, quantitative models of the agricultural sector and nutrient transport and cycling are used to analyse the impacts in the Baltic Sea of replacing the current Greening measures of the EU's Common Agricultural Policy with a package of investments in manure handling. The investments aim at improving nutrient utilization and reducing nitrogen leaching, based on the assumption that lagging farms and regions can catch up with observed good practice. Our results indicate that such investments could reduce nitrogen surpluses in agriculture by 18% and nitrogen concentrations in the Baltic Sea by 1 to 9% depending on the basin. The Greening measures, in contrast, are found to actually increase nitrogen leaching.

  • 6. Jansson, Torbjörn
    et al.
    Estrup Andersen, Hans
    Hasler, Berit
    Höglind, Lisa
    Gustafsson, Bo G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland.
    Can investments in manure technology reduce nutrient leakage to the Baltic Sea?2019Ingår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 48, nr 11Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, quantitative models of the agricultural sector and nutrient transport and cycling are used to analyse the impacts in the Baltic Sea of replacing the current Greening measures of the EU's Common Agricultural Policy with a package of investments in manure handling. The investments aim at improving nutrient utilization and reducing nitrogen leaching, based on the assumption that lagging farms and regions can catch up with observed good practice. Our results indicate that such investments could reduce nitrogen surpluses in agriculture by 18% and nitrogen concentrations in the Baltic Sea by 1 to 9% depending on the basin. The Greening measures, in contrast, are found to actually increase nitrogen leaching.

  • 7. Rydin, Emil
    et al.
    Kumblad, Linda
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Capturing past eutrophication in coastal sediments - Towards water-quality goals2019Ingår i: Estuarine, Coastal and Shelf Science, ISSN 0272-7714, E-ISSN 1096-0015, Vol. 221, s. 184-188Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Bjornofjarden is a semi-enclosed brackish bay located in the Stockholm archipelago (Baltic Sea, Sweden). Anthropogenic phosphorus (P) loading to the bay over the past century has overwhelmed the largely unchanged natural supply of elements and compounds that permanently sequester P in sediments. At the same time, eutrophication has shifted surface sediments from oxic to anoxic conditions and reduced their P-retention capacity. Consequently, the release of P from anoxic sediments has become the main P source to the water column. Here we report on a long-term remediation program to reverse eutrophication in Bjornofjarden. After the implementation of measures that reduced the land-based external load to the bay, sediment-P retention was increased by mixing a solution of aluminum (Al) chloride into the anoxic and azoic sediments (> 6 m water depth) at a dose of 50 g Al/m(2), a first in a brackish environment. As a result, P accumulation in the surface sediment reached 2.0 gP/m(2) after 14 years, corresponding to 1.6 mg P/m(2)-day. This is the first time that the P accumulation rate has been determined in aquatic sediments following the addition of P-sequestering material, such as Al. The P that accumulated was dissolved P that mainly migrated from below the layer of P accumulation. The aim of the Al-addition was to sequester legacy P that had accumulated during the past century and to return Bjornofjarden to a low productivity regime, which would allow the surface sediment to become oxic and enable natural P binding by iron.

  • 8. Villnäs, Anna
    et al.
    Janas, Urszula
    Josefson, Alf B.
    Kendzierska, Halina
    Nygård, Henrik
    Norkko, Joanna
    Norkko, Alf
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland.
    Changes in macrofaunal biological traits across estuarine gradients: implications for the coastal nutrient filter2019Ingår i: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 622, s. 31-48Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Benthic macrofaunal communities have a profound impact on organic matter turnover and nutrient cycling in marine sediments. Their activities are of particular importance in the coastal filter, where nutrients and organic matter from land are transformed and/or retained before reaching the open sea. The benthic fauna modify the coastal filter directly (through consumption, respiration, excretion and biomass production) and indirectly (through bioturbation). It is hard to experimentally quantify faunal contribution to the coastal filter over large spatial and temporal scales that encompass significant environmental and biological heterogeneity. However, estimates can be obtained with biological trait analyses. By using benthic biological traits, we explored how the potential contribution of macrofaunal communities to the coastal filter differ between inner and outer sites in an extensive archipelago area and examine the generality of the observed pattern across contrasting coastal areas of the entire Baltic Sea. Estimates of benthic bioturbation, longevity and size (i.e. 'stability') and total energy and nutrient contents differed between coastal areas and inner versus outer sites. Benthic traits indicative of an enhanced nutrient turnover but a decreased capacity for temporal nutrient retention dominated inner sites, while outer sites were often dominated by larger individuals, exhibiting traits that are likely to enhance nutrient uptake and retention. The overarching similarities in benthic trait expression between more eutrophied inner vs. less affected outer coastal sites across the Baltic Sea suggest that benthic communities might contribute in a similar manner to nutrient recycling and retention in the coastal filter over large geographical scales.

  • 9.
    Ehrnsten, Eva
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland.
    Bauer, Barbara
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. Friedrich Schiller University Jena, Germany; German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Germany.
    Gustafsson, Bo G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland.
    Combined Effects of Environmental Drivers on Marine Trophic Groups - A Systematic Model Comparison2019Ingår i: Frontiers in Marine Science, E-ISSN 2296-7745, Vol. 6, artikel-id 492Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The responses of food webs to simultaneous changes in several environmental drivers are still poorly understood. As a contribution to filling this knowledge gap, we investigated the major pathways through which two interlinked environmental drivers, eutrophication and climate, affect the biomass and community composition of fish and benthic macrofauna. For this aim, we conducted a systematic sensitivity analysis using two models simulating the dynamics of benthic and pelagic food webs in the Baltic Sea. We varied environmental forcing representing primary productivity, oxygen conditions and water temperature in all possible combinations, over a range representative of expected changes during the 21st century. Both models indicated that increased primary productivity leads to biomass increase in all parts of the system, however, counteracted by expanding hypoxia. Effects of temperature were complex, but generally small compared to the other drivers. Similarities across models give confidence in the main results, but we also found differences due to different representations of the food web in the two models. While both models predicted a shift in benthic community composition toward an increased abundance of Limecola (Macoma) balthica with increasing productivity, the effects on deposit-feeding and predatory benthic groups depended on the presence of fish predators in the model. The model results indicate that nutrient loads are a stronger driver of change for ecosystem functions in the Baltic Sea than climate change, but it is important to consider the combined effects of these drivers for proper management of the marine environment.

  • 10. Pope, John G.
    et al.
    Bartolino, Valerio
    Kulatska, Nataliia
    Bauer, Barbara
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Horbowy, Jan
    Ribeiro, Joana P. C.
    Sturludottir, Erla
    Thorpe, Robert
    Comparing the steady state results of a range of multispecies models between and across geographical areas by the use of the jacobian matrix of yield on fishing mortality rate2019Ingår i: Fisheries Research, ISSN 0165-7836, E-ISSN 1872-6763, Vol. 209, s. 259-270Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Like other fisheries models, multispecies models are subject to various sources of error. However, with regard to their use for ecosystem-based fisheries management (EBFM) between model errors are likely to be most important. As multispecies models are by definition many-dimensional, comparing them is potentially a complex task. The paper uses a simple approach. This is to calculate the Jacobian matrix of long term steady state catch by species with respect to the fishing mortality relative to status quo levels on all species. This enables the comparison of the relative strength of species interactions among models both within and between regions. This Jacobian matrix approach to comparing multispecies models is applied to available models for the North Sea, the Baltic Sea and from Icelandic waters. Moreover, this information is used to provide the basis for estimating a multidimensional quadratic yield surface for each model in the near field. Used this way it is possible to compare different model estimations of fishing mortality rate changes needed to approach yield-related management goals. The results suggest considerable variation between models in their detailed results but more coherence in suggesting directions for changing fishing mortality rate. Thus the approach is of considerable importance in specifying the confidence with which it is possible to make multispecies predictions for EBFM.

  • 11. Meysick, Lukas
    et al.
    Ysebaert, Tom
    Jansson, Anna
    Montserrat, Francesc
    Valanko, Sebastian
    Villnäs, Anna
    Boström, Christoffer
    Norkko, Joanna
    Norkko, Alf
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland.
    Context-dependent community facilitation in seagrass meadows along a hydrodynamic stress gradient2019Ingår i: Journal of Sea Research, ISSN 1385-1101, E-ISSN 1873-1414, Vol. 150, s. 8-23Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Foundation species host diverse associated communities by ameliorating environmental stress. The strength of this facilitative effect can be highly dependent on the underlying biotic and abiotic context. We investigated community level patterns of macrofauna associated with and adjacent to the marine foundation species eelgrass (Zostera marina) along a hydrodynamic stress gradient. We could demonstrate that the relative importance of this foundation species for its infaunal community increases with environmental variables associated with increasing hydrodynamic stress (depth, sand ripples formation, sediment grain size and organic content). Faunal assemblages in proximity to the Zostera patch edges, however, showed no (infauna) or negative (epifauna) response to hydrodynamic stress. Our study highlights that the facilitative outcome of a foundation species is conditional to the faunal assemblage in question and can be highly variable even between positions within the habitat.

  • 12. Hutchings, Alec M.
    et al.
    Antler, Gilad
    Wilkening, Jean
    Basu, Anirban
    Bradbury, Harold J.
    Clegg, Josephine A.
    Gorka, Marton
    Lin, Chin Yik
    Mills, Jennifer
    Pellerin, Andre
    Redeker, Kelly R.
    Sun, Xiaole
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Turchyn, Alexandra
    Creek Dynamics Determine Pond Subsurface Geochemical Heterogeneity in East Anglian (UK) Salt Marshes2019Ingår i: Frontiers in Earth Science, ISSN 2296-6463, Vol. 7, artikel-id 41Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Salt marshes are complex systems comprising ephemerally flooded, vegetated platforms hydraulically fed by tidal creeks. Where drainage is poor, formation of saline-water ponds can occur. Within East Anglian (UK) salt marshes, two types of sediment chemistries can be found beneath these ponds; iron-rich sediment, which is characterized by high ferrous iron concentration in subsurface porewaters (up to 2 mM in the upper 30 cm); and sulfide-rich sediment, which is characterized by high porewater sulfide concentrations (up to 8 mM). We present 5 years of push-core sampling to explore the geochemistry of the porewater in these two types of sediment. We suggest that when organic carbon is present in quantities sufficient to exhaust the oxygen and iron content within pond sediments, conditions favor the presence of sulfide-rich sediments. In contrast, in pond sediments where oxygen is present, primarily through bioirrigation, reduced iron can be reoxidised and thus recycled for further reduction, favoring the perpetuation of iron-rich sedimentary conditions. We find these pond sediments can alter significantly over an annual timescale. We carried out a drone survey, with ground-truthed measurements, to explore the spatial distribution of geochemistry in these ponds. Our results suggest that a pond's proximity to a creek partially determines the pond subsurface geochemistry, with iron-rich ponds tending to be closer to large creeks than sulfide-rich ponds. We suggest differences in surface delivery of organic carbon, due to differences in the energy of the ebb flow, or the surface/subsurface delivery of iron may control the distribution. This could be amplified if tidal inundations flush ponds closer to creeks more frequently, removing carbon and flushing with oxygen. These results suggest that anthropogenic creation of drainage ditches could shift the distribution of iron- and sulfide-rich ponds and thus have an impact on nutrient, trace metal and carbon cycling in salt marsh ecosystems.

  • 13.
    Broman, Elias
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik. Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Motwani, Nisha H.
    Bonaglia, Stefano
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik. University of Southern Denmark, Denmark.
    Landberg, Tommy
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Nascimento, Francisco J. A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik. Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Sjöling, Sara
    Denitrification responses to increasing cadmium exposure in Baltic Sea sediments2019Ingår i: Aquatic Toxicology, ISSN 0166-445X, E-ISSN 1879-1514, Vol. 217, artikel-id 105328Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Benthic ecosystems have come under intense pressure, due to eutrophication-driven oxygen decline and industrial metal contamination. One of the most toxic metals is Cadmium (Cd), which is lethal to many aquatic organisms already at low concentrations. Denitrification by facultative anaerobic microorganisms is an essential process to transform, but also to remove, excess nitrate in eutrophied systems. Cd has been shown to decrease denitrification and sequester free sulfide, which is available when oxygen is scarce and generally inhibits complete denitrification (i.e. N2O to N2). In polluted sediments, an interaction between oxygen and Cd may influence denitrification and this relationship has not been studied. For example, in the Baltic Sea some sediments are double exposed to both Cd and hypoxia. In this study, we examined how the double exposure of Cd and fluctuations in oxygen affects denitrification in Baltic Sea sediment. Results show that oxygen largely regulated N2O and N2 production after 21 days of exposure to Cd (ranging from 0 to 500 μg/L, 5 different treatments, measured by the isotope pairing technique (IPT)). In the high Cd treatment (500 μg/L) the variation in N2 production increased compared to the other treatments. Increases in N2 production are suggested to be an effect of 1) enhanced nitrification that increases NO3− availability thus stimulating denitrification, and 2) Cd successfully sequestrating sulfide (yielding CdS), which allows for full denitrification to N2. The in situ field sediment contained initially high Cd concentrations in the pore water (∼10 μg/L) and microbial communities might already have been adapted to metal stress, making the effect of low Cd levels negligible. Here we show that high levels of cadmium pollution might increase N2 production and influence nitrogen cycling in marine sediments.

  • 14. Norkko, Joanna
    et al.
    Pilditch, Conrad A.
    Gammal, Johanna
    Rosenberg, Rutger
    Enemar, Arvid
    Magnusson, Marina
    Granberg, Maria E.
    Lindgren, J. Fredrik
    Agrenius, Stefan
    Norkko, Alf
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland.
    Ecosystem functioning along gradients of increasing hypoxia and changing soft-sediment community types2019Ingår i: Journal of Sea Research, ISSN 1385-1101, E-ISSN 1873-1414, Vol. 153, artikel-id 101781Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Marine ecosystems world-wide are threatened by oxygen deficiency, with potential serious consequences for ecosystem functioning and the goods and services they provide. While the effects of hypoxia on benthic species diversity are well documented, the effects on ecosystem function have only rarely been assessed in real-world settings. To better understand the links between structural changes in macro- and meiofaunal communities, hypoxic stress and benthic ecosystem function (benthic nutrient fluxes, community metabolism), we sampled a total of 11 sites in Haystensfjord and Askerofjord (Swedish west coast) in late summer, coinciding with the largest extent and severity of seasonal hypoxia in the area. The sites spanned oxic to anoxic bottom water, and a corresponding gradient in faunal diversity. Intact sediment cores were incubated to measure fluxes of oxygen and nutrients (NO3-, NO2-, NH4+, PO43-, SiO4) across the sediment-water interface. Sediment profile imaging (SPI) footage was obtained from all sites to assess structural elements and the bioturbadon depth, and additional samples were collected to characterise sediment properties and macro- and meiofaunal community composition. Bottom-water O-2 concentration was the main driver of macrofauna communities, with highest abundance and biomass, as well as variability, at the sites with intermediate O-2 concentration. Meiofauna on the other hand was less sensitive to bottom-water O-2 concentration. Oxygen was the main driver of nutrient fluxes too, but macrofauna as well meiofauna were also significant predictors; DistLM analyses indicated that O-2 concentration, macrofaunal abundance or biomass, and meiofaunal abundance collectively explained 63%, 30% and 28% of the variation in sediment O-2 consumption, NH4+ flux and PO43+ flux, respectively. The study provides a step towards a more realistic understanding of the link between benthic fauna and ecosystem functioning, and the influence of disturbance on this relationship, which is important for management decisions aimed at protecting the dwindling biodiversity in the coastal zones around the world.

  • 15. Gammal, Johanna
    et al.
    Järnström, Marie
    Bernard, Guillaume
    Norkko, Joanna
    Norkko, Alf
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland.
    Environmental Context Mediates Biodiversity–Ecosystem Functioning Relationships in Coastal Soft-sediment Habitats2019Ingår i: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 22, nr 1, s. 137-151Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The ongoing loss of biodiversity and global environmental changes severely affect the structure of coastal ecosystems. Consequences, in terms of ecosystem functioning, are, however, difficult to predict because the context dependency of the biodiversity–ecosystem function relationships within these heterogeneous seascapes is poorly understood. To assess the effects of biological and environmental factors in mediating ecosystem functioning (nutrient cycling) in different natural habitats, intact sediment cores were collected at 18 sites on a grain size gradient from coarse sand to silt, with varying organic matter content and vegetation. To assess ecosystem functioning, solute fluxes (O2, NH4+, PO43−, Si) across the sediment–water interface were measured. The macrofaunal communities changed along the grain size gradient with higher abundance, biomass and number of species in coarser sediments and in habitats with more vegetation. Across the whole gradient, the macrofauna cumulatively accounted for 25% of the variability in the multivariate solute fluxes, whereas environmental variables cumulatively accounted for 20%. Only the biomass and abundance of a few of the most dominant macrofauna species, not the number of species, appeared to contribute significantly to the nutrient recycling processes. Closer analyses of different sediment types (grouped into coarse, medium and fine sediment) showed that the macrofauna was an important predictor in all sediment types, but had the largest impact in fine and medium sediments. The results imply that even if the ecosystem functioning is similar in different sediment types, the underpinning mechanisms are different, which makes it challenging to generalize patterns of functioning across the heterogeneous shallow coastal zones.

  • 16.
    Bauer, Barbara
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. Friedrich Schiller University Jena, Germany; German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Germany.
    Gustafsson, Bo G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland.
    Hyytiäinen, Kari
    Meier, H. E. Markus
    Müller-Karulis, Bärbel
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. Latvian Institute of Aquatic Ecology, Latvia.
    Saraiva, Sofia
    Tomczak, Maciej T.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Food web and fisheries in the future Baltic Sea2019Ingår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 48, nr 11, s. 1337-1349Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We developed numerical simulations of potential future ecological states of the Baltic Sea ecosystem at the end of century under five scenarios. We used a spatial food web (Ecospace) model, forced by a physical-biogeochemical model. The scenarios are built on consistent storylines that describe plausible developments of climatic and socioeconomic factors in the Baltic Sea region. Modelled species diversity and fish catches are driven by climate- and nutrient load-related changes in habitat quality and by fisheries management strategies. Our results suggest that a scenario including low greenhouse gas concentrations and nutrient pollution and ecologically focused fisheries management results in high biodiversity and catch value. On the other hand, scenarios envisioning increasing societal inequality or economic growth based on fossil fuels, high greenhouse gas emissions and high nutrient loads result in decreased habitat quality and diminished biodiversity. Under the latter scenarios catches are high but they predominantly consist of lower-valued fish.

  • 17.
    Kautsky, Lena
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Qvarfordt, Susanne
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Schagerström, Ellen
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Fucus vesiculosus adapted to a life in the Baltic Sea: impacts on recruitment, growth, re-establishment and restoration2019Ingår i: Botanica Marina, ISSN 0006-8055, E-ISSN 1437-4323, Vol. 62, nr 1, s. 17-30Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fucus vesiculosus is common both on the tidal coasts of the North Atlantic and in the Baltic Sea, where it has adapted to low salinity and nontidal conditions over the last 7000 years. During the late 1970s and early 1980s, extensive declines of F. vesiculosus populations were reported in the Baltic Proper, mainly attributed to high nutrient loads. During the past 30-40 years, considerable efforts have been made to reduce nutrient runoff to coastal areas but few successful initiatives to restore F. vesiculosus populations have been performed. In this paper, we present how substratum manipulation, i.e. clean rocky surfaces, brushing rocks, Hildenbrandia rubra cover and different filamentous algae, as well as different algal exudates, affect the recruitment and survival of juvenile F.vesiculosus. Further, we show through a 5-year field experiment that it will take at least 4-5 years to reach reproductive age for F. vesiculosus in the Baltic Sea. We also present transplantation studies from two different areas, showing that epiphytic load, light, grazing and type of substratum are some of the factors that need to be taken into consideration in order to achieve successful restoration of F. vesiculosus.

  • 18.
    Bayer, Tina K.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap och analytisk kemi.
    Gustafsson, Erik
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Brakebusch, Matthias
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap och analytisk kemi.
    Beer, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap och analytisk kemi.
    Future Carbon Emission From Boreal and Permafrost Lakes Are Sensitive to Catchment Organic Carbon Loads2019Ingår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 124, nr 7, s. 1827-1848Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Carbon storage, processing, and transport in freshwater systems are important components of the global carbon cycle and sensitive to global change. However, in large-scale modeling this part of the boundless carbon cycle is often lacking or represented in a very simplified way. A new process-oriented lake biogeochemical model is used for investigating impacts of changes in atmospheric CO2 concentrations and organic carbon loading from the catchment on future greenhouse gas emissions from lakes across two boreal to subarctic regions (Northern Sweden and Alaska). Aquatic processes represented include carbon, oxygen, phytoplankton, and nutrient dynamics leading to CO2 and CH4 exchanges with the atmosphere. The model is running inside a macroscale hydrological model and may be easily implemented into a land surface scheme. Model evaluation demonstrates the validity in terms of average concentration of nutrients, algal biomass, and organic and inorganic carbon. Cumulative annual emissions of CH4 and CO2, as well as pathways of CH4 emissions, also compare well to observations. Model calculations imply that lake emissions of CH4 may increase by up to 45% under the Representative Concentration Pathway 8.5 scenario until 2100, and CO2 emissions may increase by up to 80% in Alaska. Increasing organic carbon loading to the lakes resulted in a linear response in CO2 and CH4 emissions across both regions, but increases in CO2 emissions from subarctic lakes in Sweden were lower than for southern boreal lakes, probably due to the higher importance of imported vegetation-generated inorganic carbon for CO2 emission from subarctic lakes.

  • 19.
    Piemontese, Luigi
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholm Resilience Centre.
    Fetzer, Ingo
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholm Resilience Centre.
    Rockström, Johan
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholm Resilience Centre. Potsdam Institute for Climate Impact Research, Germany.
    Jaramillo, Fernando
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholm Resilience Centre. Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Future Hydroclimatic Impacts on Africa: Beyond the Paris Agreement2019Ingår i: Earth's Future, ISSN 1384-5160, E-ISSN 2328-4277, Vol. 7, nr 7, s. 748-761Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Projections of global warming in Africa are generally associated with increasing aridity and decreasing water availability. However, most freshwater assessments focus on single hydroclimatic indicators (e.g., runoff, precipitation, or aridity), lacking analysis on combined changes in evaporative demand, and water availability on land. There remains a high degree of uncertainty over water implications at the basin scale, in particular for the most water-consuming sector-food production. Using the Budyko framework, we perform an assessment of future hydroclimatic change for the 50 largest African basins, finding a consistent pattern of change in four distinct regions across the two main emission scenarios corresponding to the Paris Agreement, and the business as usual. Although the Paris Agreement is likely to lead to less intense changes when compared to the business as usual, both scenarios show the same pattern of hydroclimatic shifts, suggesting a potential roadmap for hydroclimatic adaptation. We discuss the social-ecological implications of the projected hydroclimatic shifts in the four regions and argue that climate policies need to be complemented by soil and water conservation practices to make the best use of future water resources.

  • 20. Barboza, Francisco R.
    et al.
    Kotta, Jonne
    Weinberger, Florian
    Jormalainen, Veijo
    Kraufvelin, Patrik
    Molis, Markus
    Schubert, Hendrik
    Pavia, Henrik
    Nylund, Göran M.
    Kautsky, Lena
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Schagerström, Ellen
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Rickert, Esther
    Saha, Mahasweta
    Fredriksen, Stein
    Martin, Georg
    Torn, Kaire
    Ruuskanen, Ari
    Wahl, Martin
    Geographic variation in fitness-related traits of the bladderwrack Fucus vesiculosus along the Baltic Sea-North Sea salinity gradient2019Ingår i: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 9, nr 16, s. 9225-9238Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the course of the ongoing global intensification and diversification of human pressures, the study of variation patterns of biological traits along environmental gradients can provide relevant information on the performance of species under shifting conditions. The pronounced salinity gradient, co-occurrence of multiple stressors, and accelerated rates of change make the Baltic Sea and its transition to North Sea a suitable region for this type of study. Focusing on the bladderwrack Fucus vesiculosus, one of the main foundation species on hard-bottoms of the Baltic Sea, we analyzed the phenotypic variation among populations occurring along 2,000 km of coasts subjected to salinities from 4 to >30 and a variety of other stressors. Morphological and biochemical traits, including palatability for grazers, were recorded at 20 stations along the Baltic Sea and four stations in the North Sea. We evaluated in a common modeling framework the relative contribution of multiple environmental drivers to the observed trait patterns. Salinity was the main and, in some cases, the only environmental driver of the geographic trait variation in F. vesiculosus. The decrease in salinity from North Sea to Baltic Sea stations was accompanied by a decline in thallus size, photosynthetic pigments, and energy storage compounds, and affected the interaction of the alga with herbivores and epibiota. For some traits, drivers that vary locally such as wave exposure, light availability or nutrient enrichment were also important. The strong genetic population structure in this macroalgae might play a role in the generation and maintenance of phenotypic patterns across geographic scales. In light of our results, the desalination process projected for the Baltic Sea could have detrimental impacts on F. vesiculosus in areas close to its tolerance limit, affecting ecosystem functions such as habitat formation, primary production, and food supply.

  • 21. Centurioni, Luca R.
    et al.
    Turton, Jon
    Lumpkin, Rick
    Braasch, Lancelot
    Brassington, Gary
    Chao, Yi
    Charpentier, Etienne
    Chen, Zhaohui
    Corlett, Gary
    Dohan, Kathleen
    Donlon, Craig
    Gallage, Champika
    Hormann, Verena
    Ignatov, Alexander
    Ingleby, Bruce
    Jensen, Robert
    Kelly-Gerreyn, Boris A.
    Koszalka, Inga M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Meteorologiska institutionen (MISU). Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Lin, Xiaopei
    Lindstrom, Eric
    Maximenko, Nikolai
    Merchant, Christopher J.
    Minnett, Peter
    O'Carroll, Anne
    Paluszkiewicz, Theresa
    Poli, Paul
    Poulain, Pierre-Marie
    Reverdin, Gilles
    Sun, Xiujun
    Swail, Val
    Thurston, Sidney
    Wu, Lixin
    Yu, Lisan
    Wang, Bin
    Zhang, Dongxiao
    Global in situ Observations of Essential Climate and Ocean Variables at the Air-Sea Interface2019Ingår i: Frontiers in Marine Science, E-ISSN 2296-7745, Vol. 6, artikel-id 419Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    The air-sea interface is a key gateway in the Earth system. It is where the atmosphere sets the ocean in motion, climate/weather-relevant air-sea processes occur, and pollutants (i.e., plastic, anthropogenic carbon dioxide, radioactive/chemical waste) enter the sea. Hence, accurate estimates and forecasts of physical and biogeochemical processes at this interface are critical for sustainable blue economy planning, growth, and disaster mitigation. Such estimates and forecasts rely on accurate and integrated in situ and satellite surface observations. High-impact uses of ocean surface observations of essential ocean/climate variables (EOVs/ECVs) include (1) assimilation into/validation of weather, ocean, and climate forecast models to improve their skill, impact, and value; (2) ocean physics studies (i.e., heat, momentum, freshwater, and biogeochemical air-sea fluxes) to further our understanding and parameterization of air-sea processes; and (3) calibration and validation of satellite ocean products (i.e., currents, temperature, salinity, sea level, ocean color, wind, and waves). We review strengths and limitations, impacts, and sustainability of in situ ocean surface observations of several ECVs and EOVs. We draw a 10-year vision of the global ocean surface observing network for improved synergy and integration with other observing systems (e.g., satellites), for modeling/forecast efforts, and for a better ocean observing governance. The context is both the applications listed above and the guidelines of frameworks such as the Global Ocean Observing System (GOOS) and Global Climate Observing System (GCOS) (both co-sponsoredby the Intergovernmental Oceanographic Commission of UNESCO, IOC-UNESCO; the World Meteorological Organization, WMO; the United Nations Environment Programme, UNEP; and the International Science Council, ISC). Networks of multiparametric platforms, such as the global drifter array, offer opportunities for new and improved in situ observations. Advances in sensor technology (e.g., low-cost wave sensors), high-throughput communications, evolving cyberinfrastructures, and data information systems with potential to improve the scope, efficiency, integration, and sustainability of the ocean surface observing system are explored.

  • 22. Powers, S. M.
    et al.
    Chowdhury, R. B.
    MacDonald, G. K.
    Metson, G. S.
    Beusen, A. H. W.
    Bouwman, A. F.
    Hampton, S. E.
    Mayer, B. K.
    McCrackin, M. L.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Vaccari, D. A.
    Global Opportunities to Increase Agricultural Independence Through Phosphorus Recycling2019Ingår i: Earth's Future, ISSN 1384-5160, E-ISSN 2328-4277, Vol. 7, nr 4, s. 370-383Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Food production hinges largely upon access to phosphorus (P) fertilizer. Most fertilizer P used in the global agricultural system comes from mining of nonrenewable phosphate rock deposits located within few countries. However, P contained in livestock manure or urban wastes represents a recyclable source of P. To inform development of P recycling technologies and policies, we examined subnational, national, and global spatial patterns for two intersections of land use affording high P recycling potential: (a) manure-rich cultivated areas and (b) populous cultivated areas. In turn, we examined overlap between P recycling potential and nation-level P fertilizer import dependency. Populous cultivated areas were less abundant globally than manure-rich cultivated areas, reflecting greater segregation between crops and people compared to crops and livestock, especially in the Americas. Based on a global hexagonal grid (290-km(2) grid cell area), disproportionately large shares of subnational hot spots for P recycling potential occurred in India, China, Southeast Asia, Europe, and parts of Africa. Outside of China, most of the remaining manure-rich or pulous cultivated areas occurred within nations that had relatively high imports of P fertilizer (net P import:consumption ratios >= 0.4) or substantial increases in fertilizer demand between the 2000s (2002-2006) and 2010s (2010-2014). Manure-rich cultivated grid cells (those above the 75th percentiles for both manure and cropland extent) represented 12% of the global grid after excluding cropless cells. Annually, the global sum of animal manure P was at least 5 times that contained in human excreta, and among cultivated cells the ratio was frequently higher (median = 8.9). The abundance of potential P recycling hot spots within nations that have depended on fertilizer imports or experienced rising fertilizer demand could prove useful for developing local P sources and maintaining agricultural independence.

  • 23.
    Humborg, Christoph
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland.
    Geibel, Marc C.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Sun, Xiaole
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    McCrackin, Michelle
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Mörth, Carl-Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    Stranne, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    Jakobsson, Martin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    Gustafsson, Bo
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland.
    Sokolov, Alexander
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Norkko, Alf
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland.
    Norkko, Joanna
    High Emissions of Carbon Dioxide and Methane From the Coastal Baltic Sea at the End of a Summer Heat Wave2019Ingår i: Frontiers in Marine Science, E-ISSN 2296-7745, Vol. 6, artikel-id 493Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The summer heat wave in 2018 led to the highest recorded water temperatures since 1926 - up to 21 degrees C - in bottom coastal waters of the Baltic Sea, with implications for the respiration patterns in these shallow coastal systems. We applied cavity ring-down spectrometer measurements to continuously monitor carbon dioxide (CO2) and methane (CH4) surface-water concentrations, covering the coastal archipelagos of Sweden and Finland and the open and deeper parts of the Northern Baltic Proper. This allowed us to (i) follow an upwelling event near the Swedish coast leading to elevated CO2 and moderate CH 4 outgassing, and (ii) to estimate CH4 sources and fluxes along the coast by investigating water column inventories and air-sea fluxes during a storm and an associated downwelling event. At the end of the heat wave, before the storm event, we found elevated CO2 (1583 mu atm) and CH4 (70 nmol/L) concentrations. During the storm, a massive CO2 sea-air flux of up to 274 mmol m(-2) d(-1) was observed. While water-column CO2 concentrations were depleted during several hours of the storm, CH4 concentrations remained elevated. Overall, we found a positive relationship between CO2 and CH4 wind-driven sea-air fluxes, however, the highest CH4 fluxes were observed at low winds whereas highest CO2 fluxes were during peak winds, suggesting different sources and processes controlling their fluxes besides wind. We applied a box-model approach to estimate the CH4 supply needed to sustain these elevated CH4 concentrations and the results suggest a large source flux of CH4 to the water column of 2.5 mmol m(-2) d(-1). These results are qualitatively supported by acoustic observations of vigorous and widespread outgassing from the sediments, with flares that could be traced throughout the water column penetrating the pycnocline and reaching the sea surface. The results suggest that the heat wave triggered CO2 and CH4 fluxes in the coastal zones that are comparable with maximum emission rates found in other hot spots, such as boreal and arctic lakes and wetlands. Further, the results suggest that heat waves are as important for CO2 and CH4 sea-air fluxes as the ice break up in spring.

  • 24. Virtanen, Elina A.
    et al.
    Norkko, Alf
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland.
    Nyström Sandman, Antonia
    Viitasalo, Markku
    Identifying areas prone to coastal hypoxia - the role of topography2019Ingår i: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 16, nr 16, s. 3183-3195Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hypoxia is an increasing problem in marine ecosystems around the world. While major advances have been made in our understanding of the drivers of hypoxia, challenges remain in describing oxygen dynamics in coastal regions. The complexity of many coastal areas and lack of detailed in situ data have hindered the development of models describing oxygen dynamics at a sufficient spatial resolution for efficient management actions to take place. It is well known that the enclosed nature of seafloors and reduced water mixing facilitates hypoxia formation, but the degree to which topography contributes to hypoxia formation and small-scale variability of coastal hypoxia has not been previously quantified. We developed simple proxies of seafloor heterogeneity and modeled oxygen deficiency in complex coastal areas in the northern Baltic Sea. According to our models, topographical parameters alone explained similar to 80 % of hypoxia occurrences. The models also revealed that less than 25 % of the studied seascapes were prone to hypoxia during late summer (August-September). However, large variation existed in the spatial and temporal patterns of hypoxia, as certain areas were prone to occasional severe hypoxia (O-2 < 2 mg L-1), while others were more susceptible to recurrent moderate hypoxia (O-2 < 4.6 mg L-1). Areas identified as problematic in our study were characterized by low exposure to wave forcing, high topographic shelter from surrounding areas and isolation from the open sea, all contributing to longer water residence times in seabed depressions. Deviations from this topographical background are probably caused by strong currents or high nutrient loading, thus improving or worsening oxygen status, respectively. In some areas, connectivity with adjacent deeper basins may also influence coastal oxygen dynamics. Developed models could boost the performance of biogeochemical models, aid developing nutrient abatement measures and pinpoint areas where management actions are most urgently needed.

  • 25. Zhang, Zhouling
    et al.
    Sun, Xiaole
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Dai, Minhan
    Cao, Zhimian
    Fontorbe, Guillaume
    Conley, Daniel J.
    Impact of human disturbance on the biogeochemical silicon cycle in a coastal sea revealed by silicon isotopes2019Ingår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Biogeochemical silicon (Si) cycling in coastal systems is highly influenced by anthropogenic perturbations in recent decades. Here, we present a systematic study on the distribution of stable Si isotopes of dissolved silicate (delta Si-30(DSi)) in a highly eutrophic coastal system, the Baltic Sea. Besides the well-known processes, diatom production and dissolution regulating delta Si-30(DSi) values in the water column, we combined field data with a box model to examine the role of human disturbances on Si cycling in the Baltic Sea. Results reveal that (1) damming led to increased delta Si-30(DSi) values in water but had little impacts on their vertical distribution; (2) decrease in saltwater inflow due to enhanced thermal stratification had negligible impacts on the delta Si-30(DSi) distribution. An atypical vertical distribution of delta Si-30(DSi) with higher values in deep water (1.57-1.95 parts per thousand) relative to those in surface water (1.24-1.68 parts per thousand) was observed in the central basin. Model results suggest the role of enhanced biogenic silica (BSi) deposition and subsequently regenerated dissolved silicate (DSi) flux from sediments. Specifically, eutrophication enhances diatom production, resulting in elevated exports of highly fractionated BSi to deep water and sediments. In situ sedimentary geochemical processes, such as authigenic clay formation, further fractionate Si isotopes and increase pore-water delta Si-30(DSi) values, which then leads to pore-water DSi flux carrying higher delta Si-30(DSi) compositions into deep water. Our findings provide new quantitative information on how the isotope-based Si cycle responds to human perturbations in coastal seas and shed lights on shifts of Si export to open ocean.

  • 26. Hermans, Martijn
    et al.
    K. Lenstra, Wytze
    van Helmond, Niels A. G. M.
    Behrends, Thilo
    Egger, Matthias
    Séguret, Marie J. M.
    Gustafsson, Erik
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum, Baltic Nest Institute.
    Gustafsson, Bo G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum, Baltic Nest Institute. University of Helsinki, Finland.
    Slomp, Caroline P.
    Impact of natural re-oxygenation on the sediment dynamics of manganese, iron and phosphorus in a euxinic Baltic Sea basin2019Ingår i: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 246, s. 174-196Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Baltic Sea is characterized by the largest area of hypoxic (oxygen (O2) < 2 mg L−1) bottom waters in the world’s ocean induced by human activities. Natural ventilation of these O2-depleted waters largely depends on episodic Major Baltic Inflows from the adjacent North Sea. In 2014 and 2015, two such inflows led to a strong rise in O2 and decline in phosphate (HPO42−) in waters below 125 m depth in the Eastern Gotland Basin. This provided the opportunity to assess the impact of such re-oxygenation events on the cycles of manganese (Mn), iron (Fe) and phosphorus (P) in the sediment for the first time. We demonstrate that the re-oxygenation induced the activity of sulphur (S)-oxidising bacteria, known as Beggiatoaceae in the surface sediment where a thin oxic and suboxic layer developed. At the two deepest sites, strong enrichments of total Mn and to a lesser extent Fe oxides and P were observed in this surface layer. A combination of sequential sediment extractions and synchrotron-based X-ray spectroscopy revealed evidence for the abundant presence of P-bearing rhodochrosite and Mn(II) phosphates. In contrast to what is typically assumed, the formation of Fe oxides in the surface sediment was limited. We attribute this lack of Fe oxide formation to the high flux of reductants, such as sulphide, from deeper sediments which allows Fe(II) in the form of FeS to be preserved and restricts the penetration of O2 into the sediment. We estimate that enhanced P sequestration in surface sediments accounts for only ∼5% of water column HPO42− removal in the Eastern Gotland Basin linked to the recent inflows. The remaining HPO42− was transported to adjacent areas in the Baltic Sea. Our results highlight that the benthic O2 demand arising from the accumulation of organic-rich sediments over several decades, the legacy of hypoxia, has major implications for the biogeochemical response of euxinic basins to re-oxygenation. In particular, P sequestration in the sediment in association with Fe oxides is limited. This implies that artificial ventilation projects that aim at removing water column HPO42− and thereby improving water quality in the Baltic Sea will likely not have the desired effect.

  • 27.
    Svedäng, Henrik
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. Swedish Institute for the Marine Environment (SIME), Sweden; Swedish University of Agricultural Sciences (SLU), Sweden.
    Barth, Julia M. I.
    Svensson, Anders
    Jonsson, Patrik
    Jentoft, Sissel
    Knutsen, Halvor
    André, Carl
    Local cod (Gadus morhua) revealed by egg surveys and population genetic analysis after longstanding depletion on the Swedish Skagerrak coast2019Ingår i: ICES Journal of Marine Science, ISSN 1054-3139, E-ISSN 1095-9289, Vol. 76, nr 2, s. 418-429Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Dramatic and persistent reductions in Atlantic cod (Gadus morhua) are common in many coastal areas. While offshore cod stocks still were abundant and productive, the Swedish west coast showed signs of diminishing adult cod abundance at the beginning of the 1980s, where the local cod component was considered to be extirpated. To survey the present cod spawning activity and stock composition, we initiated egg trawling over two consecutive years (203 hauls in total) in combination with population genetic analyses (425 individually genotyped eggs). Here, we provide evidence of cod spawning at the Swedish Skagerrak coast, suggesting recolonization or that local cod has recovered from a nearly depleted state. Early stage eggs were found inside fjords too far to have been transported by oceanic drift from offshore spawning areas. The cod eggs were genetically similar in early to late life-stages and cluster mainly with the local adult cod, indicating that eggs and adults belong to the same genetic unit. The cod eggs were genetically differentiated from adult North Sea cod, and, to a lesser degree, also from the Kattegat and Öresund cod, i.e. indicating a possible recovery of local coastal stock.

    The patterns of the genetic structure in the inshore areas are, however, difficult to fully disentangle, as Atlantic cod in the North Sea-Skagerrak area seem to be a mixture of co-existing forms: local cod completing their entire life cycle in fjords and sheltered areas, and oceanic populations showing homing behaviours. The egg abundances are considerably lower compared with what is found in similar studies along the Norwegian Skagerrak coast. Nevertheless, the discovery of locally spawning cod along the Swedish west coast—although at low biomasses—is an encouraging finding that highlights the needs for endurance in protective measures and of detailed surveys to secure intraspecific biodiversity and ecosystem services.

  • 28.
    Bauer, Barbara
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. German Centre for Integrative Biodiversity Research (iDiv), Germany.
    Horbowy, Jan
    Rahikainen, Mika
    Kulatska, Nataliia
    Müller-Karulis, Bärbel
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Tomczak, Maciej T.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Bartolino, Valerio
    Model uncertainty and simulated multispecies fisheries management advice in the Baltic Sea2019Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 14, nr 1, artikel-id e0211320Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Different ecosystem models often provide contrasting predictions (model uncertainty), which is perceived to be a major challenge impeding their use to support ecosystem-based fisheries management (EBFM). The focus of this manuscript is to examine the extent of model disagreements which could impact management advice for EBFM in the central Baltic Sea. We compare how much three models (EwE, Gadget and a multispecies stock production model) differ in 1) their estimates of fishing mortality rates (Fs) satisfying alternative hypothetical management scenario objectives and 2) the outcomes of those scenarios in terms of performance indicators (spawning stock biomasses, catches, profits). Uncertainty in future environmental conditions affecting fish was taken into account by considering two seal population growth scenarios and two nutrient load scenarios. Differences in the development of the stocks, yields and profits exist among the models but the general patterns are also sufficiently similar to appear promising in the context of strategic fishery advice. Thus, we suggest that disagreements among the ecosystem models will not impede their use for providing strategic advice on how to reach management objectives that go beyond the traditional maximum yield targets and for informing on the potential consequences of pursuing such objectives. This is especially true for scenarios aiming at exploiting forage fish sprat and herring, for which the agreement was the largest among our models. However, the quantitative response to altering fishing pressure differed among models. This was due to the diverse environmental covariates and the different number of trophic relationships and their functional forms considered in the models. This suggests that ecosystem models can be used to provide quantitative advice only after more targeted research is conducted to gain a deeper understanding into the relationship between trophic links and fish population dynamics in the Baltic Sea.

  • 29. Villnas, Anna
    et al.
    Norkko, Alf
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland.
    Lehtonen, Kari K.
    Multi-level responses of Macoma balthica to recurring hypoxic disturbance2019Ingår i: Journal of Experimental Marine Biology and Ecology, ISSN 0022-0981, E-ISSN 1879-1697, Vol. 510, s. 64-72Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The frequency of seasonal and short-term hypoxia is increasing in coastal seas. How such repeated disturbances affect key species that have important roles for ecosystem processes and functions remains, however, unknown. By performing a field experiment we explored if the bivalve Macoma balthica can cope with short-term, recurring hypoxic stress, and investigated how hypoxia affects the condition of surviving bivalves. By combining data on different levels of biological organization, i.e., on physiology (biomarker response), behaviour and demography, we identified stress responses before the population declined. One pulse of hypoxic disturbance (3 days) resulted in behavioural alterations, as adult M. balthica extended their siphons, emerged towards the sediment surface and expressed decreased reburial rates. However, the demographic structure of the population remained unaltered. Several pulses of recurring hypoxic stress resulted in physiological response with changes in glutathione reductase and acetylcholinesterase enzyme activities. The recurring hypoxic disturbance was observed to affect juvenile bivalves before adults, while pro-longed hypoxia reduced the entire bivalve population. Our results clearly show that hypoxic stress changes the behaviour and physiology of M. balthica before demographic changes occur, which is likely to have severe implications for the contribution of this key species to ecosystem functioning. That a combination of measures at different levels of organization can detect disturbances at an early stage suggests that such an approach would be useful for assessing the effects of disturbances on marine ecosystems that are increasingly affected by anthropogenic change.

  • 30. Westerbom, Mats
    et al.
    Mustonen, Olli
    Jaatinen, Kim
    Kilpi, Mikael
    Norkko, Alf
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. Helsinki University, Finland.
    Population Dynamics at the Range Margin: Implications of Climate Change on Sublittoral Blue Mussels (Mytilus trossulus)2019Ingår i: Frontiers in Marine Science, E-ISSN 2296-7745, Vol. 6, artikel-id UNSP 292Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Examining changes in abundance and demographic rates at species distribution margins may provide the first signs of broader species responses to environmental change. Still, the joint impact of space and time have remained relatively unstudied in most marginal regions. In order to examine the influence of climate variability on mussel distribution patterns, we monitored three sublittoral and marginal blue mussel (Mytilus trossulus) populations, spaced along a salinity gradient. Densities and biomasses peaked toward the saltier parts of the study area and showed relatively larger variations toward the low saline edge. Temporally, the areas showed a consistent increase in abundance after a synchronized large-scale recruitment event, which was followed by a decline in population size, occurring much faster toward the very range edge. Salinity, temperature, winter severity, and wave exposure explained most of the spatiotemporal variation in mussel abundances and adults showed positive effects on recruit abundance. We show empirically that the dynamics of edge populations are not driven by large changes in climate variables but that small spatial and temporal changes in key environmental variables have large and non-linear population level effects. Our results also show that fluctuating recruitment is a key factor for population stability affecting the storage potential of marginal populations, which dramatically decrease toward the edge. Our study provides a window into future population patterns and processes that drive marginal mussel populations in an altered sea characterized by rising temperature and declining salinity.

  • 31.
    Jaramillo, Fernando
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Stockholm Resilience Centre. Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Desormeaux, Amanda
    Hedlund, Johanna
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholm Resilience Centre.
    Jawitz, James W.
    Clerici, Nicola
    Piemontese, Luigi
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholm Resilience Centre.
    Alexandra Rodríguez-Rodriguez, Jenny
    Adolfo Anaya, Jesús
    Blanco-Libreros, Juan F.
    Borja, Sonia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Celi, Jorge
    Chalov, Sergey
    Chun, Kwok Pan
    Cresso, Matilda
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Destouni, Georgia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Dessu, Shimelis Behailu
    Di Baldassarre, Giuliano
    Downing, Andrea
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholm Resilience Centre.
    Espinosa, Luisa
    Ghajarnia, Navid
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Girard, Pierre
    Gutiérrez, Álvaro G.
    Hansen, Amy
    Hu, Tengfei
    Jarsjö, Jerker
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Kalantary, Zahra
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Labbaci, Adnane
    Licero-Villanueva, Lucia
    Livsey, John
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Machotka, Ewa
    Stockholms universitet, Humanistiska fakulteten, Institutionen för Asien-, Mellanöstern- och Turkietstudier.
    McCurley, Kathryn
    Palomino-Ángel, Sebastián
    Pietron, Jan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Price, René
    Ramchunder, Sorain J.
    Ricaurte-Villota, Constanza
    Ricaurte, Luisa Fernanda
    Dahir, Lula
    Rodríguez, Erasmo
    Salgado, Jorge
    Sannel, A. Britta K.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Carolina Santos, Ana
    Seifollahi-Aghmiuni, Samaneh
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Sjöberg, Ylva
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Sun, Lian
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Beijing Normal University, China.
    Thorslund, Josefin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Vigouroux, Guillaume
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Wang-Erlandsson, Lan
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholm Resilience Centre.
    Xu, Diandian
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Hohai University, China.
    Zamora, David
    Ziegler, Alan D.
    Åhlén, Imenne
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Priorities and Interactions of Sustainable Development Goals (SDGs) with Focus on Wetlands2019Ingår i: Water, ISSN 2073-4441, E-ISSN 2073-4441, Vol. 11, nr 3, artikel-id 619Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Wetlands are often vital physical and social components of a country's natural capital, as well as providers of ecosystem services to local and national communities. We performed a network analysis to prioritize Sustainable Development Goal (SDG) targets for sustainable development in iconic wetlands and wetlandscapes around the world. The analysis was based on the information and perceptions on 45 wetlandscapes worldwide by 49 wetland researchers of the Global Wetland Ecohydrological Network (GWEN). We identified three 2030 Agenda targets of high priority across the wetlandscapes needed to achieve sustainable development: Target 6.3-Improve water quality; 2.4-Sustainable food production; and 12.2-Sustainable management of resources. Moreover, we found specific feedback mechanisms and synergies between SDG targets in the context of wetlands. The most consistent reinforcing interactions were the influence of Target 12.2 on 8.4-Efficient resource consumption; and that of Target 6.3 on 12.2. The wetlandscapes could be differentiated in four bundles of distinctive priority SDG-targets: Basic human needs, Sustainable tourism, Environmental impact in urban wetlands, and Improving and conserving environment. In general, we find that the SDG groups, targets, and interactions stress that maintaining good water quality and a wise use of wetlandscapes are vital to attaining sustainable development within these sensitive ecosystems.

  • 32. Bernard, Guillaume
    et al.
    Gammal, Johanna
    Järnström, Marie
    Norkko, Joanna
    Norkko, Alf
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland.
    Quantifying bioturbation across coastal seascapes: Habitat characteristics modify effects of macrofaunal communities2019Ingår i: Journal of Sea Research, ISSN 1385-1101, E-ISSN 1873-1414, Vol. 152, artikel-id 101766Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Bioturbation by benthic macrofauna communities plays a significant role in the setting and maintenance of important ecosystem functions and the delivery of associated ecosystem services. We investigated the context dependence of bioturbation performed by natural benthic communities in the coastal northern Baltic Sea by quantifying three bioturbation metrics (particle mixing intensity, surface sediment reworking and bioturbation depth) across 18 sites ranging from cohesive muddy sediments to non-cohesive coarse sands, while accounting for the complexity of natural communities and habitat characteristics. We identified two distinct patterns of bioturbation; in fine sediments bioturbation rates were highly variable and in coarse sediments bioturbation rates were less variable and characterized by lower maximal values. Using distance-based linear multiple regressions, we found that 75.5% of the variance in bioturbation rates in fine sediment could be explained by key functional groups/species abundance and/or biomass (i.e. biomass of the gallery-diffusors and abundances of biodiffusors, surface modifiers, conveyors and gallery diffusors, respectively). In coarse sediment, 47.8% of the variance in bioturbation rates could be explained by a combination of environmental factors (grain size, organic matter content, buried plant material) and faunal functional groups, although fauna alone explained only 13% of this variance. Bioturbation in fine sediments was therefore more predictable based on the composition of benthic fauna. In coarse sediment, the bioturbation activities of benthic fauna were strongly modified by habitat characteristics (including the presence of buried plant material, sediment organic content and grain size) whereas in fine sediments this was not the case. Our results therefore highlight that variability in spatial patterns of bioturbation is a result of complex relationships between macrofauna community structure, sediment type and other habitat characteristics, likely modifying bioturbation performance of individual fauna.

  • 33. Gustafsson, Camilla
    et al.
    Norkko, Alf
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland.
    Quantifying the importance of functional traits for primary production in aquatic plant communities2019Ingår i: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 107, nr 1, s. 154-166Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    1. Aquatic plant meadows are important coastal habitats that sustain many ecosystem functions such as primary production and carbon sequestration. Currently, there is a knowledge gap in understanding which plant functional traits, for example, leaf size or plant height underlie primary production in aquatic plant communities.

    2. To study how plant traits are related to primary production, we conducted a field survey in the Baltic Sea, Finland, which is characterized by high plant species and functional diversity. Thirty sites along an exposure gradient were sampled (150 plots), and nine plant morphological and chemical traits measured. The aim was to discern how community-weighted mean traits affect community production and whether this relationship changes along an environmental gradient using structural equation modelling (SEM).

    3. Plant height had a direct positive effect on production along an exposure gradient (r=0.33) and indirect effects through two leaf chemical traits, leaf delta N-15 and leaf delta C-13 (r=0.24 and 0.18, respectively) resulting in a total effect of 0.28. In plant communities experiencing varying exposure, traits such as root N concentration and leaf delta N-15 had positive and negative effects on production, respectively.

    4. Synthesis. Our results demonstrate that the relationship between aquatic plant functional traits and community production is variable and changes over environmental gradients. Plant height generally has a positive effect on community production along an exposure gradient, while the link between other traits and production changes in plant communities experiencing varying degrees of exposure. Thus, the underlying biological mechanisms influencing production differ in plant communities, emphasizing the need to resolve variability and its drivers in real-world communities. Importantly, functionally diverse plant communities sustain ecosystem functioning differently and highlight the importance of benthic diversity for coastal ecosystem stability.

  • 34.
    Hansen, Joakim P.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Sundblad, Göran
    Bergström, Ulf
    N. Austin, Åsa
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Donadi, Serena
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik. Swedish University of Agricultural Sciences (SLU), Sweden.
    Eriksson, Britas Klemens
    Eklöf, Johan S.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Recreational boating degrades vegetation important for fish recruitment2019Ingår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 48, nr 6, s. 539-551Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recreational boating increases globally and associated moorings are often placed in vegetated habitats important for fish recruitment. Meanwhile, assessments of the effects of boating on vegetation, and potential effects on associated fish assemblages are rare. Here, we analysed (i) the effect of small-boat marinas on vegetation structure, and (ii) juvenile fish abundance in relation to vegetation cover in shallow wave-sheltered coastal inlets. We found marinas to have lower vegetation cover and height, and a different species composition, compared to control inlets. This effect became stronger with increasing berth density. Moreover, there was a clear positive relationship between vegetation cover and fish abundance. We conclude that recreational boating and related moorings are associated with reduced cover of aquatic vegetation constituting important habitats for juvenile fish. We therefore recommend that coastal constructions and associated boating should be allocated to more disturbance tolerant environments (e.g. naturally wave-exposed shores), thereby minimizing negative environmental impacts.

  • 35.
    Svanbäck, Annika
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    McCrackin, Michelle L.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Swaney, Dennis P.
    Linefur, Helena
    Gustafsson, Bo G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland.
    Howarth, Robert W.
    Humborg, Christoph
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland.
    Reducing agricultural nutrient surpluses in a large catchment - Links to livestock density2019Ingår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 648, s. 1549-1559Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The separation between crop- and livestock production is an important driver of agricultural nutrient surpluses in many parts of the world. Nutrient surpluses can be symptomatic of poor resource use efficiency and contribute to environmental problems. Thus, it is important not only to identify where surpluses can be reduced, but also the potential policy tools that could facilitate reductions. Here, we explored linkages between livestock production and nutrient flows for the Baltic Sea catchment and discuss management practices and policies that influence the magnitude of nutrient surpluses. We found that the majority of nutrients cycled through the livestock sector and that large nitrogen and phosphorus surpluses often occurred in regions with high livestock density. Imports of mineral fertilizers and feed to the catchment increased overall surpluses, which in turn increased the risk of nutrient losses from agriculture to the aquatic environment. Many things can be done to reduce agricultural nutrient surpluses; an important example is using manure nutrients more efficiently in crop production, thereby reducing the need to import mineral fertilizers. Also, existing soil P reserves could be used to a greater extent, which further emphasizes the need to improve nutrient management practices. The countries around the Baltic Sea used different approaches to manage agricultural nutrient surpluses, and because eight of the coastal countries are members in the European Union (EU), common EU policies play an important role in management. We observed reductions in surpluses between 2000 and 2010 in some countries, which suggested the influence of different approaches to management and policy and that there are opportunities for further improvement. However, the separation between crop and livestock production in agriculture appears to be an underlying cause of nutrient surpluses; thus, further research is needed to understand how policy can address these structural issues and increase sustainability in food production.

  • 36.
    Fransner, Filippa
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Meteorologiska institutionen (MISU).
    Fransson, Agneta
    Humborg, Christoph
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland.
    Gustafsson, Erik
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum, Baltic Nest Institute.
    Tedesco, Letizia
    Hordoir, Robinson
    Nycander, Jonas
    Stockholms universitet, Naturvetenskapliga fakulteten, Meteorologiska institutionen (MISU).
    Remineralization rate of terrestrial DOC as inferred from CO2 supersaturated coastal waters2019Ingår i: Biogeosciences Discussions, ISSN 1810-6277, E-ISSN 1810-6285, Vol. 16, nr 3, s. 863-879Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Coastal seas receive large amounts of terrestrially derived organic carbon (OC). The fate of this carbon, and its impact on the marine environment, is however poorly understood. Here we combine underway CO2 partial pressure (pCO2) measurements with coupled 3D hydrodynamical-biogeochemical modelling to investigate whether remineralization of terrestrial dissolved organic carbon (tDOC) can explain CO2 supersaturated surface waters in the Gulf of Bothnia, a subarctic estuary. We find that a substantial remineralization of tDOC, and that a strong tDOC induced light attenuation dampening the primary production, is required to reproduce the observed CO2 supersaturated waters in the nearshore areas. A removal rate of tDOC of the order of one year, estimated in a previous modelling study in the same area, gives a good agreement between modelled and observed pCO2. The remineralization rate is on the same order as bacterial degradation rates calculated from published incubation experiments, suggesting that this remineralization could be caused by bacterial degradation. Furthermore, the observed high pCO2 values during the ice covered season argues against photochemical degradation as the main removal mechanism. All of the remineralized tDOC is outgassed to the atmosphere in the model, turning the northernmost part of the Gulf of Bothnia to a source of atmospheric CO2.

  • 37. Asmala, Eero
    et al.
    Gustafsson, Camilla
    Krause-Jensen, Dorte
    Norkko, Alf
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland.
    Reader, Heather
    Staehr, Peter A.
    Carstensen, Jacob
    Role of Eelgrass in the Coastal Filter of Contrasting Baltic Sea Environments2019Ingår i: Estuaries and Coasts, ISSN 1559-2723, E-ISSN 1559-2731, Vol. 42, nr 7, s. 1882-1895Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Coastal ecosystems act as filters of nutrients from land to the open sea. We investigated the role of eelgrass (Zostera marina) metabolism in the coastal filter transforming nitrogen, phosphorus, and organic carbon. Field campaigns following identical methodologies were carried out at two contrasting coastal locations: the mesohaline and nutrient-rich Roskilde Fjord, Denmark, and the mesotrophic brackish Tvarminne archipelago, Finland. Over the 24-h in situ benthic incubations, we measured oxygen concentrations continuously and assessed changes in DOM characteristics and net fluxes of carbon, nitrogen, and phosphorus. Ecosystem metabolism modeled on the basis of the O-2 data showed that the systems were either net heterotrophic (Roskilde Fjord; - 1.6 and - 2.4 g O-2 m(-2) day(-1) in eelgrass meadow and bare sand, respectively) or had balanced primary production and respiration (Tvarminne; 0.0 and 0.2 g O-2 m(-2) day(-1)). Overall, initial nutrient stoichiometry was a key factor determining benthic-pelagic fluxes of nutrients, which exacerbated the deviations from Redfield ratios of N and P, indicating an efficient use of the limiting nutrient. A net diel uptake of dissolved inorganic N was observed at both locations (- 2.3 mu mol l(-1) day(-1) in Roskilde Fjord and - 0.1 mu mol l(-1) day(-1) in Tvarminne). Despite minor changes in dissolved organic carbon concentrations during the incubations, a marked increase of fluorescent DOM was observed at both locations, suggesting rapid heterotrophic processing of the DOM pool. Our results underline that the biogeochemical role of eelgrass in the coastal filter is not inherent, but strongly dependent on the environmental conditions.

  • 38.
    Broman, Elias
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik. Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Raymond, Caroline
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Sommer, Christian
    Gunnarsson, Jonas S.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Creer, Simon
    Nascimento, Francisco J. A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik. Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Salinity drives meiofaunal community structure dynamics across the Baltic ecosystem2019Ingår i: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 28, nr 16, s. 3813-3829Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Coastal benthic biodiversity is under increased pressure from climate change, eutrophication, hypoxia, and changes in salinity due to increase in river runoff. The Baltic Sea is a large brackish system characterized by steep environmental gradients that experiences all of the mentioned stressors. As such it provides an ideal model system for studying the impact of on‐going and future climate change on biodiversity and function of benthic ecosystems. Meiofauna (animals < 1 mm) are abundant in sediment and are still largely unexplored even though they are known to regulate organic matter degradation and nutrient cycling. In this study, benthic meiofaunal community structure was analysed along a salinity gradient in the Baltic Sea proper using high‐throughput sequencing. Our results demonstrate that areas with higher salinity have a higher biodiversity, and salinity is probably the main driver influencing meiofauna diversity and community composition. Furthermore, in the more diverse and saline environments a larger amount of nematode genera classified as predators prevailed, and meiofauna‐macrofauna associations were more prominent. These findings show that in the Baltic Sea, a decrease in salinity resulting from accelerated climate change will probably lead to decreased benthic biodiversity, and cause profound changes in benthic communities, with potential consequences for ecosystem stability, functions and services.

  • 39.
    Rodil, Iván F.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland; University of Porto, Portugal.
    Lastra, Mariano
    López, Jesús
    Mucha, Ana P.
    Fernandes, Joana P.
    Fernandes, Sara V.
    Olabarria, Celia
    Sandy Beaches as Biogeochemical Hotspots: The Metabolic Role of Macroalgal Wrack on Low-productive Shores2019Ingår i: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 22, nr 1, s. 49-63Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sandy beaches, which represent the most common type of land-sea interface, harbor distinctive biotic communities and regulate the flow of energy between marine and terrestrial ecosystems. Accumulations of sea wrack on sandy beaches are of crucial importance for recycling beach nutrients and for regulating trophic connectivity and coastal functioning. We investigated the role of beaches as biogeochemical hotspots by examining the metabolic activity in accumulations of different species of wrack on two exposed beaches affected by different levels of human pressure. Experimental wrack patches provided large amounts of different sedimentary nutrients over time due to remineralization of the algae. Unsurprisingly, the variation in the nutrients present in the beach sediments was related to the species of wrack considered. Macroalgal wrack was metabolically very active and supported high respiration rates represented by intense CO2 fluxes. Importantly, we demonstrated that the wrack metabolic rate differed significantly depending on the algal species considered. Different macrofauna and bacterial assemblages were identified in the different wrack patches and on the different beaches. We suggest that human activities such as beach grooming can modify the wrack-associated communities, thus contributing to the variability in the biogeochemical processes and metabolic rates. Significant changes in the type and amount of wrack deposited on beaches can change fundamental processes related to the marine-terrestrial transfer of nutrients and energy and to the marine-atmospheric transfer of CO2 emissions, with ecological consequences for nearshore environments.

  • 40. Attard, Karl M.
    et al.
    Rodil, Iván F.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland.
    Glud, Ronnie N.
    Berg, Peter
    Norkko, Joanna
    Norkko, Alf
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland.
    Seasonal ecosystem metabolism across shallow benthic habitats measured by aquatic eddy covariance2019Ingår i: Limnology and oceanography letters, ISSN 2378-2242, Vol. 4, nr 3, s. 79-86Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Shallow benthic habitats are hotspots for carbon cycling and energy flow, but metabolism (primary production and respiration) dynamics and habitat-specific differences remain poorly understood. We investigated daily, seasonal, and annual metabolism in six key benthic habitats in the Baltic Sea using similar to 2900h of in situ aquatic eddy covariance oxygen flux measurements. Rocky substrates had the highest metabolism rates. Habitat-specific annual primary production per m(2) was in the order Fucus vesiculosus canopy>Mytilus trossulus reef>Zostera marina canopy>mixed macrophytes canopy>sands, whereas respiration was in the order M. trossulus>F. vesiculosus>Z. marina>mixed macrophytes> sands>aphotic sediments. Winter metabolism contributed 22-31% of annual rates. Spatial upscaling revealed that benthic habitats drive >90% of ecosystem metabolism in waters <= 5 m depth, highlighting their central role in carbon and nutrient cycling in shallow waters.

  • 41. Attard, K. M.
    et al.
    Rodil, Iván F.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland.
    Berg, P.
    Norkko, J.
    Norkko, Alf
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. University of Helsinki, Finland.
    Glud, R. N.
    Seasonal metabolism and carbon export potential of a key coastal habitat: The perennial canopy-forming macroalga Fucus vesiculosus2019Ingår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 64, nr 1, s. 149-164Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The important role of macroalgal canopies in the oceanic carbon (C) cycle is increasingly being recognized, but direct assessments of community productivity remain scarce. We conducted a seasonal study on a sublittoral Baltic Sea canopy of the brown alga Fucus vesiculosus, a prominent species in temperate and Arctic waters. We investigated community production on hourly, daily, and seasonal timescales. Aquatic eddy covariance (AEC) oxygen flux measurements integrated similar to 40 m(2) of the seabed surface area and documented considerable oxygen production by the canopy year-round. High net oxygen production rates of up to 35 +/- 9 mmol m(-2) h(-1) were measured under peak irradiance of similar to 1200 mu mol photosynthetically active radiation (PAR) m(-2) s(-1) in summer. However, high rates > 15 mmol m(-2) h(-1) were also measured in late winter (March) under low light intensities < 250 mu mol PAR m(-2) s(-1) and water temperatures of similar to 1 degrees C. In some cases, hourly AEC fluxes documented an apparent release of oxygen by the canopy under dark conditions, which may be due to gas storage dynamics within internal air spaces of F. vesiculosus. Daily net ecosystem metabolism (NEM) was positive (net autotrophic) in all but one of the five measurement campaigns (December). A simple regression model predicted a net autotrophic canopy for two-thirds of the year, and annual canopy NEM amounted to 25 mol O-2 m(-2) yr(-1), approximately six-fold higher than net phytoplankton production. Canopy C export was similar to 0.3 kg C m(-2) yr(-1), comparable to canopy standing biomass in summer. Macroalgal canopies thus represent regions of intensified C assimilation and export in coastal waters.

  • 42.
    Gustafsson, Erik
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum, Baltic Nest Institute.
    Hagens, Mathilde
    Sun, Xiaole
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Reed, Daniel C.
    Humborg, Christoph
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum. Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap och analytisk kemi. University of Helsinki, Finland.
    Slomp, Caroline P.
    Gustafsson, Bo G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum, Baltic Nest Institute. University of Helsinki, Finland.
    Sedimentary alkalinity generation and long-term alkalinity development in the Baltic Sea2019Ingår i: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 16, nr 2, s. 437-456Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Enhanced release of alkalinity from the seafloor, principally driven by anaerobic degradation of organic matter under low-oxygen conditions and associated secondary redox reactions, can increase the carbon dioxide (CO2) buffering capacity of seawater and therefore oceanic CO2 uptake. The Baltic Sea has undergone severe changes in oxygenation state and total alkalinity (TA) over the past decades. The link between these conc