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  • 1. Agstam-Norlin, O.
    et al.
    Lannergård, E. E.
    Rydin, Emil
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Futter, M. N.
    Huser, B. J.
    A 25-year retrospective analysis of factors influencing success of aluminum treatment for lake restoration2021In: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 200, article id 117267Article in journal (Refereed)
    Abstract [en]

    For more than 50 years, aluminum (Al)-salts have been used with varying degrees of success to inactivate excess mobile phosphorus (P) in lake sediments and restore lake water quality. Here, we analyzed the factors influencing effectiveness and longevity of Al-treatments performed in six Swedish lakes over the past 25 years. Trends in post-treatment measurements of total phosphorus (TP), Chlorophyll a (Chl_a), Secchi disk depth (SD) and internal P loading rates (Li) were analyzed and compared to pre-treatment conditions. All measured water quality parameters improved significantly during at least the first 4 years post-treatment and determination of direct effects of Al-treatment on sediment P release (Li) was possible for three lakes. Improvements in TP (-29 to -80%), Chl_a (-50 to -78%), SD (7 to 121%) and Li (-68 to -94%) were observed. Treatment longevity, determined via decreases in surface water TP after treatment, varied from 7 to >47 years. Lake type, Al dose, and relative watershed area were related to longevity. In addition, greater binding efficiency between Al and P was positively related to treatment longevity, which has not previously been shown. Our findings also demonstrate that adequate, long-term monitoring programs, including proper determination of external loads, are crucial to document the effect of Al-treatment on sediment P release and lake water quality.

  • 2. Ahlgren, Joakim
    et al.
    Grimvall, Anders
    Omstedt, Anders
    Rolff, Carl
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. Swedish Institute for the Marine Environment, Sweden.
    Wikner, Johan
    Temperature, DOC level and basin interactions explain the declining oxygen concentrations in the Bothnian Sea2017In: Journal of Marine Systems, ISSN 0924-7963, E-ISSN 1879-1573, Vol. 170, p. 22-30Article in journal (Refereed)
    Abstract [en]

    Hypoxia and oxygen deficient zones are expanding worldwide. To properly manage this deterioration of the marine environment, it is important to identify the causes of oxygen declines and the influence of anthropogenic activities. Here, we provide a study aiming to explain the declining oxygen levels in the deep waters of the Bothnian Sea over the past 20 years by investigating data from environmental monitoring programmes. The observed decline in oxygen concentrations in deep waters was found to be primarily a consequence of water temperature increase and partly caused by an increase in dissolved organic carbon (DOC) in the seawater (R-Adj(2). = 0.83) as well as inflow from the adjacent sea basin. As none of the tested eutrophication-related predictors were significant according to a stepwise multiple regression, a regional increase in nutrient inputs to the area is unlikely to explain a significant portion of the oxygen decline. Based on the findings of this study, preventing the development of anoxia in the deep water of the Bothnian Sea is dependent on the large-scale measures taken to reduce climate change. In addition, the reduction of the nutrient load to the Baltic Proper is required to counteract the development of hypoxic and phosphate-rich water in the Baltic Proper, which can form deep water in the Bothnian Sea. The relative importance of these sources to oxygen consumption is difficult to determine from the available data, but the results clearly demonstrate the importance of climate related factors such as temperature, DOC and inflow from adjacent basins for the oxygen status of the sea.

  • 3.
    Albert, Séréna
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Bonaglia, Stefano
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. University of Southern Denmark, Denmark; University of Gothenburg, Sweden.
    Stjärnkvist, Nellie
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Winder, Monika
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Thamdrup, Bo
    Nascimento, Francisco J. A
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Influence of settling organic matter quantity and quality on benthic nitrogen cycling2021In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 66, no 5, p. 1882-1895Article in journal (Refereed)
    Abstract [en]

    Coastal sediments are major contributors to global carbon (C) mineralization and nutrient cycling and are tightly linked to processes in the pelagic environment. In this study, we aimed to investigate the regulating potential of quantity and quality of planktonic organic matter (OM) deposition on benthic metabolism, with a particular focus on nitrogen (N) cycling processes. We simulated inputs of spring (C : N 10.9) and summer (C : N 5.6) plankton communities in high and low quantities to sediment cores, and followed oxygen consumption, nutrient fluxes as well as nitrate reduction rates, that is, denitrification and dissimilatory nitrate reduction to ammonium for 10 d. Our results demonstrate the primary importance of OM quality in determining the fate of organic N once it settles to the sediment surface. Settling of N-rich summer plankton material resulted in a similar to twofold lower denitrification efficiency (40-56%) compared to N-poor spring plankton (88-115%). This indicates that N-rich plankton deposition favors recycling of inorganic nutrients to the water column over N-loss via denitrification. OM quantity was positively related to mineralization activity, but this neither directly affected N fluxes nor denitrification activity, highlighting the complex interplay between the OM quantity and quality in regulating N cycling. In light of these new findings, we support the use of simple qualitative indicators such as C : N ratio of OM to investigate how future changes in benthic-pelagic coupling might influence N budgets at the sediment-water interface.

  • 4.
    Albert, Séréna
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Hedberg, Per
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Motwani, Nisha H.
    Sjöling, Sara
    Winder, Monika
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Nascimento, Francisco J. A.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Phytoplankton settling quality has a subtle but significant effect on sediment microeukaryotic and bacterial communities2021In: Scientific Reports, E-ISSN 2045-2322, Vol. 11, no 1, article id 24033Article in journal (Refereed)
    Abstract [en]

    In coastal aphotic sediments, organic matter (OM) input from phytoplankton is the primary food resource for benthic organisms. Current observations from temperate ecosystems like the Baltic Sea report a decline in spring bloom diatoms, while summer cyanobacteria blooms are becoming more frequent and intense. These climate-driven changes in phytoplankton communities may in turn have important consequences for benthic biodiversity and ecosystem functions, but such questions are not yet sufficiently explored experimentally. Here, in a 4-week experiment, we investigated the response of microeukaryotic and bacterial communities to different types of OM inputs comprising five ratios of two common phytoplankton species in the Baltic Sea, the diatom Skeletonema marinoi and filamentous cyanobacterium Nodularia spumigena. Metabarcoding analyses on 16S and 18S ribosomal RNA (rRNA) at the experiment termination revealed subtle but significant changes in diversity and community composition of microeukaryotes in response to settling OM quality. Sediment bacteria were less affected, although we observed a clear effect on denitrification gene expression (nirS and nosZ), which was positively correlated with increasing proportions of cyanobacteria. Altogether, these results suggest that future changes in OM input to the seafloor may have important effects on both the composition and function of microbenthic communities.

  • 5.
    Albert, Séréna
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Liénart, Camilla
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Winder, Monika
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Nascimento, Francisco
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Seasonality and drivers of microeukaryotic and bacterial communities in Baltic Sea soft sedimentsManuscript (preprint) (Other academic)
  • 6. Alexander, Karen A.
    et al.
    Heymans, Johanna J.
    Magill, Shona
    Tomczak, Maciej T.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Holmes, Steven J.
    Wilding, Thomas A.
    Investigating the recent decline in gadoid stocks in the west of Scotland shelf ecosystem using a foodweb model2015In: ICES Journal of Marine Science, ISSN 1054-3139, E-ISSN 1095-9289, Vol. 72, no 2, p. 436-449Article in journal (Refereed)
    Abstract [en]

    Abundance and biomass of cod, haddock, and whiting in the waters off of the west coast of Scotland (wcoS) have undergone large changes in recent years, most notably a recent decline. These three species contribute a considerable part of Scottish demersal landings from this area and as such it is important to understand why these stocks are behaving the way they are. A number of explanations for the decline have been proposed, including: seal predation, pressure from Nephrops trawls, and fishing pressure more generally. We used an ecosystem model of the wcoS continental shelf (<200 m depth) to investigate whether these proposed explanations for declining gadoid stocks are feasible. Results suggest that the rise in the grey seal population over recent years has not led to the decline in gadoid stocks; there is insufficient bycatch by the Nephrops fleet to have a large impact on gadoid stocks; however, fishing, as a key driver of the west of Scotland shelf ecosystem, has impacted stocks and by decreasing fishing levels to maximum sustainable yield cod biomass may increase slightly though not returning to previous levels. Although this means we are little further forward in understanding the cause of recent gadoid declines in the area, the development of this model has enabled us to further our knowledge and understanding of aspects of trophic structure and the impacts of fishing on the wcoS.

  • 7. Alsaffar, Z.
    et al.
    Pearman, J. K.
    Cúrdia, J.
    Ellis, J.
    Calleja, M. Ll
    Ruiz-Compean, P.
    Roth, Florian
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. King Abdullah University of Science and Technology (KAUST), Saudi Arabia; Tvärminne Zoological Station, Finland.
    Villalobos, R.
    Jones, B. H.
    Morán, X. A. G.
    Carvalho, S.
    The role of seagrass vegetation and local environmental conditions in shaping benthic bacterial and macroinvertebrate communities in a tropical coastal lagoon2020In: Scientific Reports, E-ISSN 2045-2322, Vol. 10, no 1, article id 13550Article in journal (Refereed)
    Abstract [en]

    We investigated the influence of seagrass canopies on the benthic biodiversity of bacteria and macroinvertebrates in a Red Sea tropical lagoon. Changes in abundance, number of taxa and assemblage structure were analyzed in response to seagrass densities (low, SLD; high, SHD; seagrasses with algae, SA), and compared with unvegetated sediments. Biological and environmental variables were examined in these four habitats (hereafter called treatments), both in the underlaying sediments and overlaying waters, at three randomly picked locations in March 2017. Differences between treatments were more apparent in the benthic habitat than in the overlaying waters. The presence of vegetation (more than its cover) and changes in sedimentary features (grain size and metals) at local scales influenced the observed biological patterns, particularly for macroinvertebrates. Of note, the highest percentage of exclusive macroinvertebrate taxa (18% of the gamma diversity) was observed in the SHD treatment peaking in the SA for bacteria. Benthic macroinvertebrates and bacteria shared a generally low number of taxa across treatments and locations; approximately, 25% of the gamma diversity was shared among all treatments and locations for macrofauna, dropping to 11% for bacteria. Given the low overlap in the species distribution across the lagoon, sustaining the connectivity among heterogeneous soft sediment habitats appears to be essential for maintaining regional biodiversity. This study addresses a current scientific gap related to the relative contributions of vegetated and unvegetated habitats to biodiversity in tropical regions.

  • 8.
    Aminjafari, Saeid
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography. Stockholm University, Faculty of Science, The Bolin Centre for Climate Research (together with KTH & SMHI).
    Brown, Ian A.
    Stockholm University, Faculty of Science, Department of Physical Geography. Stockholm University, Faculty of Science, The Bolin Centre for Climate Research (together with KTH & SMHI).
    Frappart, F.
    Papa, F.
    Blarel, F.
    Vahidi Mayamey, Farzad
    Stockholm University, Faculty of Science, Department of Physical Geography. Stockholm University, Faculty of Science, The Bolin Centre for Climate Research (together with KTH & SMHI).
    Jaramillo, Fernando
    Stockholm University, Faculty of Science, Department of Physical Geography. Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. Stockholm University, Faculty of Science, Stockholm Resilience Centre. Stockholm University, Faculty of Science, The Bolin Centre for Climate Research (together with KTH & SMHI).
    Distinctive Patterns of Water Level Change in Swedish Lakes Driven by Climate and Human Regulation2024In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 60, no 3, article id e2023WR036160Article in journal (Refereed)
    Abstract [en]

    Despite having approximately 100,000 lakes, Sweden has limited continuous gauged lake water level data. Although satellite radar altimetry (RA) has emerged as a popular alternative to measure water levels in inland water bodies, it has not yet been used to understand the large-scale changes in Swedish lakes. Here, we quantify the changes in water levels in 144 lakes using RA data and in situ gauged measurements to examine the effects of flow regulation and hydroclimatic variability. We use data from several RA missions, including ERS-2, ENVISAT, JASON-1,2,3, SARAL, and Sentinel-3A/B. We found that during 1995–2022, around 52% of the lakes exhibited an increasing trend and 43% a decreasing trend. Most lakes exhibiting an increasing trend were in the north of Sweden, while most lakes showing a decreasing trend were in the south. Regarding the potential effects of regulation, we found that unregulated lakes had smaller trends in water level and dynamic storage than regulated ones. While the seasonal patterns of water levels in the lakes in the north are similar in regulated and unregulated lakes, in the south, they differ substantially. This study highlights the need to continuously monitor lake water levels for adaptation strategies in the face of climate change and understand the downstream effects of water regulatory schemes.

  • 9.
    Aminjafari, Saeid
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Brown, Ian
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Chalov, Sergey
    Simard, Marc
    Lane, Charles R.
    Jarsjö, Jerker
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Darvishi, Mehdi
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Jaramillo, Fernando
    Stockholm University, Faculty of Science, Department of Physical Geography. Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Drivers and extent of surface water occurrence in the Selenga River Delta, Russia2021In: Journal of Hydrology: Regional Studies, E-ISSN 2214-5818, Vol. 38, article id 100945Article in journal (Refereed)
    Abstract [en]

    Study region: Selenga River Delta (SRD), Russia.

    Study focus: How is water occurrence changing in the SRD, and what are the hydroclimatic drivers behind these changes? The presence of water on the surface in river deltas is governed by land use, geomorphology, and the flux of water to and from the Delta. We trained an accurate image classification of the Landsat satellite imagery during the last 33 years to quantify surface water occurrence and its changes in the SRD. After comparing our estimations with global-scale data sets, we determined the hydrological drivers of these changes.

    New hydrological insights for the region: We find mild decreases in water occurrence in 51% of the SRD's surface area from 1987-2002 to 2003-2020. Water occurrence in the most affected areas decreased by 20% and in the most water-gaining areas increased by 10%. We find a significant relationship between water occurrence and runoff (R-2 = 0.56) that does not exist between water occurrence and suspended sediment concentration (SSC), Lake Baikal's water level, and potential evapotranspiration. The time series of water occurrence follows the peaks in the runoff but not its long-term trend. However, the extremes in SSC do not influence surface water occurrence (R-2 < 0.1), although their long-term trends are similar. Contrary to expected, we find that the Delta has a relatively stable long-term water availability for the time being.

  • 10.
    Aminjafari, Saeid
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Brown, Ian
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Frappart, Frédéric
    ISPA, INRAE/Bordeaux Sciences Agro.
    Papa, Fabrice
    LEGOS, Université de Toulouse.
    Blarel, Fabien
    LEGOS, Université de Toulouse.
    Farzad, Vahidi Mayamey
    Jaramillo, Fernando
    Stockholm University, Faculty of Science, Department of Physical Geography. Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. Stockholm University, Faculty of Science, Stockholm Resilience Centre. Stockholm University, Faculty of Science, The Bolin Centre for Climate Research (together with KTH & SMHI).
    Assessing the Effects of Regulation on Swedish Lake Water Levels with Satellite AltimetryManuscript (preprint) (Other academic)
    Abstract [en]

    Lakes are important sources of freshwater for human activities and provide critical ecosystem services. However, despite having approximately 100,000 lakes, Sweden has limited continuous gauged water level data. Although satellite radar altimetry has emerged as a popular alternative to measure water levels in inland water bodies, it is yet to be exploited to understand large-scale changes in inland water bodies in Sweden. Here, we quantify the changes in water levels of 144 lakes using satellite altimetry data and in-situ gauged measurements and examine the effects of flow regulation and hydroclimatic variability. Data from multiple altimetry missions, including ERS-2, ENVISAT, JASON-1,2,3, SARAL, and Sentinel-3A/B, are employed to estimate the variability and yearly and seasonal trends of water levels in two periods, 1995-2022 and 2013-2022. Our study finds that water levels significantly increased in 52% of the lakes during 1995-2022. The increasing trends primarily occurred in northern Sweden and are potentially attributed to earlier snowmelt. On the other hand, 43% of the lakes exhibited a significant decreasing trend, which was mostly concentrated in Southern Sweden. Dividing the set of lakes into regulated and unregulated groups shows how lake regulation in Sweden can partly explain the spatial patterns of water levels and their variability. This study highlights the need to continuously monitor lake water levels for adaptation strategies in the face of climate change and understand the downstream effects of water regulatory schemes.

  • 11.
    Aminjafari, Saeid
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Brown, Ian
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Jaramillo, Fernando
    Stockholm University, Faculty of Science, Department of Physical Geography. Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. Stockholm University, Faculty of Science, Stockholm Resilience Centre. Stockholm University, Faculty of Science, The Bolin Centre for Climate Research (together with KTH & SMHI).
    Evaluating D-InSAR Performance to Detect Small Water Level Fluctuations in LakesManuscript (preprint) (Other academic)
    Abstract [en]

    It is essential to track lake water level fluctuations, however, the number of conventional gauging stations is declining worldwide due to impractical installation and maintenance procedures. Satellite altimetry is a substitute for traditional gauges. Nevertheless, altimetry sensors cannot identify small lakes owing to poor spatial coverage. Their application is limited to lakes falling exactly below the path of the altimeter. Differential Interferometric Synthetic Aperture Radar (D-InSAR) is commonly used to track land deformation and water surface changes, with the latter being comparatively limited and focused mainly on wetlands. We here explore the potential of D-InSAR to track water level changes in two Swedish lakes, focusing on the shoreline in search of potential double-bounce backscattering and analyzing pixel phase changes and coherence. We use Sentinel-1A and Sentinel-1B data from 2019, generate six-day interferograms, and exclude those when corresponding to in-situ water level changes exceeding one phase cycle. We find that D-InSAR is sensitive to minor water level changes, obtaining Lin's correlations of up to 0.63 and 0.89 (RMSE = 9 & 4 mm, respectively). These results evidence the potential of future L-band SAR missions with larger wavelengths, such as NISAR, to track water level changes in lakes and aid water tracking missions such as the SWOT.

  • 12.
    Aminjafari, Saeid
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Brown, Ian
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Vahidi Mayamey, Farzad
    Jaramillo, Fernando
    Stockholm University, Faculty of Science, Department of Physical Geography. Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. Stockholm University, Faculty of Science, Stockholm Resilience Centre. Stockholm University, Faculty of Science, The Bolin Centre for Climate Research (together with KTH & SMHI).
    The Potential of D-InSAR for Water Level Estimation in Swedish LakesManuscript (preprint) (Other academic)
    Abstract [en]

    Lakes are valuable water resources that support aquatic and terrestrial ecosystems and supply fresh water for the agricultural, industrial, and urban sectors worldwide. Although water levels should be tracked to monitor these services, conventional gauging is unfeasible in most lakes. This study explores the potential, advantages, and limitations of using Differential Interferometric Synthetic Aperture Radar (D-InSAR) to estimate small water level changes in lakes (i.e., less than the full cycle of the SAR signal) and overall long-term direction of change. We validated the method across the shores of 30 Swedish lakes with gauged observations during 2019. We used Sentinel-1A/B images with a six-day temporal separation to construct consecutive interferograms and accumulated the phase changes in pixels of high coherence to build time series of water levels. We find that the accumulated phase change replicates the magnitude of water levels in seven lakes in Southern Sweden, where water level changes seldom exceed a complete SAR phase (i.e., 1.8 cm in the vertical direction), evident from the Concordance Correlation Coefficients (0.30 < CCC < 0.55). Furthermore, D-InSAR can estimate the long-term direction of water level change (i.e., increase or decrease) in all 30 lakes. We elaborate on the possible explanation for this last finding. The novel methodology could be used to validate future altimetry missions such as SWOT in lakes worldwide and can be improved with upcoming SAR missions with longer wavelengths.

  • 13.
    Aminjafari, Saeid
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography. Stockholm University, Faculty of Science, The Bolin Centre for Climate Research (together with KTH & SMHI).
    Brown, Ian
    Stockholm University, Faculty of Science, Department of Physical Geography. Stockholm University, Faculty of Science, The Bolin Centre for Climate Research (together with KTH & SMHI).
    Vahidi Mayamey, Farzad
    Stockholm University, Faculty of Science, Department of Physical Geography. Stockholm University, Faculty of Science, The Bolin Centre for Climate Research (together with KTH & SMHI).
    Jaramillo, Fernando
    Stockholm University, Faculty of Science, Department of Physical Geography. Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. Stockholm University, Faculty of Science, Stockholm Resilience Centre. Stockholm University, Faculty of Science, The Bolin Centre for Climate Research (together with KTH & SMHI).
    Tracking Centimeter-Scale Water Level Changes in Swedish Lakes Using D-InSAR2024In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 60, no 2, article id e2022WR034290Article in journal (Refereed)
    Abstract [en]

    Lakes are valuable water resources that support aquatic and terrestrial ecosystems and supply fresh water for the agricultural, industrial, and urban sectors worldwide. Although water levels should be tracked to monitor these services, conventional gauging is unfeasible in most lakes. This study applies Differential Interferometric Synthetic Aperture Radar (D-InSAR) to estimate small water level changes, less than 2 cm, in Swedish lakes over 6-day intervals. We validated the method across the shores of 30 Swedish lakes with gauged observations in 2019. We used Sentinel-1A/B images with a 6-day temporal separation to construct consecutive interferograms and accumulated the phase changes in pixels of high coherence to build a time series of water levels. We find that the accumulated phase change obtained by D-InSAR replicates the magnitude of water levels in seven lakes in Southern Sweden, where water levels change slowly, less than 2 cm per 6-day period, as validated by in-situ gauges. In addition, this study demonstrates the application of D-InSAR to estimate the long-term direction of water level change (i.e., increase or decrease) in all 30 lakes. This work reveals the utility of high temporal resolution water level observations in support of other satellite water level instruments such as conventional altimeters and the recently launched Surface Water and Ocean Topography Mission.

  • 14.
    Ammar, Yosr
    et al.
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Puntila-Dodd, Riikka
    Department of Aquatic Sciences, University of Helsinki, Helsinki, Finland.
    Tomczak, Maciej T.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Nyström, Magnus
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Blenckner, Thorsten
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Exploring future ecosystem novelty and resilience using the adaptive cycleManuscript (preprint) (Other academic)
    Abstract [en]

    Marine ecosystems worldwide are under unprecedented pressure from the impacts of climate change and human activities. Such pressure increased novelty in species assemblages, i.e., assemblages increasingly outside their historical range of variation. It may further rise in the future, and whether it will unfold and influence resilience remains unclear. Using the adaptive cycle, we explore the relationship between resilience and novelty under the compound effect of climate, nutrient load, and fishing management scenarios in the Finnish Archipelago Sea (FAS) future food web model. Novelty was measured as the minimum dissimilarity over time relative to a specific baseline. Ecological Network Analysis indices associated to the model: ascendancy, capacity, and overhead flow, were used as indicators of connectedness, potential, and resilience axes of the adaptive cycle. A model-based clustering method distinguished four regimes determined by the impact of the nutrient load and climate on the bottom-up dynamic of the FAS food web. Resilience decreased in regimes where higher and faster novelty emerged in response to warmer climate pathways. The number of reorganization phases of the adaptive cycle, characterized by the generation of novelty, was greater in regimes under low nutrient load management scenarios. We highlight the importance of understanding ecosystem reorganization and resilience in a growing Anthropogenic novelty to inform future management. 

  • 15. Andersen, Hans Estrup
    et al.
    Blicher-Mathiesen, Gitte
    Thodsen, Hans
    Mejlhede Andersen, Peter
    Larsen, Søren E.
    Stålnacke, Per
    Humborg, Christoph
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Mörth, Carl-Magnus
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Smedberg, Erik
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Identifying Hot Spots of Agricultural Nitrogen Loss Within the Baltic Sea Drainage Basin2016In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 227, no 1Article in journal (Refereed)
    Abstract [en]

    Agricultural management practices are among the major drivers of agricultural nitrogen (N) loss. Legislation and management incentives for measures to mitigate N loss should eventually be carried out at the individual farm level. Consequently, an appropriate scale to simulate N loss from a scientific perspective should be at the farm scale. A data set of more than 4000 agricultural fields with combinations of climate, soils and agricultural management which overall describes the variations found in the Baltic Sea drainage basin was constructed. The soil-vegetation-atmosphere model Daisy (Hansen et al. 2012) was used to simulate N loss from the root zone of all agricultural fields in the data set. From the data set of Daisy simulations, we identified the most important drivers for N loss by multiple regression statistics and developed a statistical N loss model. By applying this model to a basin-wide data set on climate, soils and agricultural management at a 10 x 10 km scale, we were able to calculate root-zone N losses from the entire Baltic Sea drainage basin and identify N loss hot spots in a consistent way and at a level of detail not hitherto seen for this area. Further, the root-zone N loss model was coupled to estimates of nitrogen retention in catchments separated into retention in groundwater and retention in surface waters allowing calculation of the coastal N loading.

  • 16. Andersen, Jesper H.
    et al.
    Carstensen, Jacob
    Conley, Daniel J.
    Dromph, Karsten
    Fleming-Lehtinen, Vivi
    Gustafsson, Bo G.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre, Baltic Nest Institute.
    Josefson, Alf B.
    Norkko, Alf
    Villnäs, Anna
    Murray, Ciarán
    Long-term temporal and spatial trends in eutrophication status of the Baltic Sea2017In: Biological Reviews, ISSN 1464-7931, E-ISSN 1469-185X, Vol. 92, no 1, p. 135-149Article in journal (Refereed)
    Abstract [en]

    Much of the Baltic Sea is currently classified as 'affected by eutrophication'. The causes for this are twofold. First, current levels of nutrient inputs (nitrogen and phosphorus) from human activities exceed the natural processing capacity with an accumulation of nutrients in the Baltic Sea over the last 50-100 years. Secondly, the Baltic Sea is naturally susceptible to nutrient enrichment due to a combination of long retention times and stratification restricting ventilation of deep waters. Here, based on a unique data set collated from research activities and long-term monitoring programs, we report on the temporal and spatial trends of eutrophication status for the open Baltic Sea over a 112-year period using the HELCOM Eutrophication Assessment Tool (HEAT 3.0). Further, we analyse variation in the confidence of the eutrophication status assessment based on a systematic quantitative approach using coefficients of variation in the observations. The classifications in our assessment indicate that the first signs of eutrophication emerged in the mid-1950s and the central parts of the Baltic Sea changed from being unaffected by eutrophication to being affected. We document improvements in eutrophication status that are direct consequences of long-term efforts to reduce the inputs of nutrients. The reductions in both nitrogen and phosphorus loads have led to large-scale alleviation of eutrophication and to a healthier Baltic Sea. Reduced confidence in our assessment is seen more recently due to reductions in the scope of monitoring programs. Our study sets a baseline for implementation of the ecosystem-based management strategies and policies currently in place including the EU Marine Strategy Framework Directives and the HELCOM Baltic Sea Action Plan.

  • 17. Anderson, Leif G.
    et al.
    Ek, Jörgen
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Ericson, Ylva
    Humborg, Christoph
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Semiletov, Igor
    Sundbom, Marcus
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Ulfsbo, Adam
    Export of calcium carbonate corrosive waters from the East Siberian Sea2017In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 14, no 7, p. 1811-1823Article in journal (Refereed)
    Abstract [en]

    The Siberian shelf seas are areas of extensive biogeochemical transformation of organic matter, both of marine and terrestrial origin. This in combination with brine production from sea ice formation results in a cold bottom water of relative high salinity and partial pressure of carbon dioxide (pCO(2)). Data from the SWERUS-C3 expedition compiled on the icebreaker Oden in July to September 2014 show the distribution of such waters at the outer shelf, as well as their export into the deep central Arctic basins. Very high pCO(2) water, up to similar to 1000 mu atm, was observed associated with high nutrients and low oxygen concentrations. Consequently, this water had low saturation state with respect to calcium carbonate down to less than 0.8 for calcite and 0.5 for aragonite. Waters undersaturated in aragonite were also observed in the surface in waters at equilibrium with atmospheric CO2; however, at these conditions the cause of undersaturation was low salinity from river runoff and/or sea ice melt. The calcium carbonate corrosive water was observed all along the continental margin and well out into the deep Makarov and Canada basins at a depth from about 50 m depth in the west to about 150 m in the east. These waters of low aragonite saturation state are traced in historic data to the Canada Basin and in the waters flowing out of the Arctic Ocean north of Greenland and in the western Fram Strait, thus potentially impacting the marine life in the North Atlantic Ocean.

  • 18. Angove, Charlotte
    et al.
    Norkko, Alf
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. University of Helsinki, Finland.
    Gustafsson, Camilla
    Assessing the efficiencies and challenges for nutrient uptake by aquatic plants2018In: Journal of Experimental Marine Biology and Ecology, ISSN 0022-0981, E-ISSN 1879-1697, Vol. 507, p. 23-30Article in journal (Refereed)
    Abstract [en]

    Aquatic plant meadows are valuable components to the 'coastal filter' and it is important to understand the processes that drive their ability to cycle nutrients. However, at present, the field-based evidence for understanding the drivers of nutrient uptake by plants is lacking. This study aimed to investigate how well individual shoots of aquatic plants could meet their nitrogen demands using the sediment nutrient pool (porewater ammonium) and to explore which traits helped to facilitate such uptake. Several species were investigated in shallow, submerged (2-4 m) mixed-species communities in the northern Baltic Sea using incubation experiments with enriched ammonium. After a 3.5 h incubation time, individuals were collected and analysed for nitrogen (% DW) and N-15 (at-%) concentrations. Uptake by plants was calculated per unit nitrogen in response to the N-15 labelled source and to overall nitrogen availability. Background porewater ammonium availability was highly variable between individual plants. Species identity did not significantly affect uptake metrics and the effect of ambient porewater availability was weak. As biomass increased there were significant logarithmic declines in the 95th quantiles of nutrient uptake rates, ambient porewater nutrient availability and aboveground nitrogen tissue concentrations (% DW). Such findings suggested that uptake rates of plants were significantly demand driven and the nutrient conditions of the porewater were significantly driven by the demands of the plant. Findings parameterised the unfulfilled potential for some aquatic plants to cycle nutrients more efficiently and highlighted the potential importance of access to new nutrient sources as a way of enhancing nutrient cycling by aquatic plants. Plant traits and community properties such as the activity of infauna could facilitate such an access and are likely important for nutrient uptake.

  • 19. Angove, Charlotte
    et al.
    Norkko, Alf
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. University of Helsinki, Finland.
    Gustafsson, Camilla
    The Fight to Capture Light: Functional Diversity Is Related to Aquatic Plant Community Productivity Likely by Enhancing Light Capture2020In: Frontiers in Marine Science, E-ISSN 2296-7745, Vol. 7, article id 140Article in journal (Refereed)
    Abstract [en]

    Functional diversity (FD) experiments are highly effective for investigating how a community interacts with its environment. However, such experiments using morphological and chemical traits have not been conducted for submerged aquatic plants and their insights would be highly valuable for understanding the ecology of these communities. We conducted a 15-week field experiment in the Baltic Sea where we manipulated the species composition of aquatic plant communities to investigate functional diversity. We constructed artificial triculture communities with different species compositions to change the Community Weighted Means (CWMs) and variability of traits. We measured nine plant traits and tested how community productivity (CP) was related to FD, trait CWMs and community trait ranges. CP varied by more than four times across treatments and functional richness was significantly related to CP. Functional evenness and functional divergence were not significantly related to CR Height, leaf area and delta C-13 were significantly related to CP. Leaf delta C-13 trends with CP suggested that the carbon supply is not replete, yet species composition was partly responsible for the relationship. Plant height likely had multifaceted benefits to CP because there was evidence of a competitive height interaction between the tallest and 2 nd tallest species, therefore the effects of plant height to CP would have been disproportionally large. The height of the tallest species significantly drove the variability of the community height range, which was significantly related to CP and it had a relatively large influence on the calculation of FD indices. Leaf area, which was strongly correlated to plant height, was also significantly related to CR The significant relationship between functional richness and CP was most likely driven by the presence of taller plants. FD likely enhanced CP, by selecting for extreme trait values which enhanced production (selection effect), while niche complementarity effects were not observed. This study provides experimental evidence and mechanistic insights into the role of FD and specific traits for CP in submerged aquatic plant communities. To conclude, FD was significantly related to CP of temperate aquatic plant communities likely by selecting for traits which enhanced light capture, with consequences for carbon supply.

  • 20. Aronsson, Helena
    et al.
    Nyström, Sofia
    Malmer, Elsa
    Kumblad, Linda
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Winqvist, Camilla
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Losses of phosphorus, potassium and nitrogen from horse manure left on the ground2022In: Acta Agriculturae Scandinavica - Section B, ISSN 0906-4710, E-ISSN 1651-1913, Vol. 72, no 1, p. 893-901Article in journal (Refereed)
    Abstract [en]

    In this five-month Swedish field study, we examined losses of nutrients from horse manure over time, in order to examine how regularly manure should be cleared from paddocks in order to minimise the risk of nutrient leaching. Small heaps of manure (400 g) were placed in open cylinders outdoors and samples (five replicates) were taken on 12 occasions from December 2020 to May 2021. The samples were analysed for weight, dry matter content and concentrations of total nitrogen (N), ammonium N, total phosphorus (P), water-extractable P (WEP), potassium (K) and carbon (C). There was a fast decline in P and K concentrations and a strong correlation between accumulated precipitation and losses from the manure into the soil. The mean reduction in total-P was 11 mg P kg−1 manure dry weight per mm accumulated precipitation. Manure N was retained in the manure over the five-month period. In conclusion, this study demonstrated high mobility of P and K, indicating a need for strategies for rapid removal of manure from paddocks. Daily removal of manure from paddocks used year-round would, approximately, save 1.7 kg P and 5.5 kg K per horse per year, which could be recycled to replace non-renewable mineral fertilisers.

  • 21. Asmala, Eero
    et al.
    Gustafsson, Camilla
    Krause-Jensen, Dorte
    Norkko, Alf
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. University of Helsinki, Finland.
    Reader, Heather
    Staehr, Peter A.
    Carstensen, Jacob
    Role of Eelgrass in the Coastal Filter of Contrasting Baltic Sea Environments2019In: Estuaries and Coasts, ISSN 1559-2723, E-ISSN 1559-2731, Vol. 42, no 7, p. 1882-1895Article in journal (Refereed)
    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.

  • 22. Attard, K. M.
    et al.
    Rodil, Iván F.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. University of Helsinki, Finland.
    Berg, P.
    Norkko, J.
    Norkko, Alf
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. University of Helsinki, Finland.
    Glud, R. N.
    Seasonal metabolism and carbon export potential of a key coastal habitat: The perennial canopy-forming macroalga Fucus vesiculosus2019In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 64, no 1, p. 149-164Article in journal (Refereed)
    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.

  • 23. Attard, Karl M.
    et al.
    Rodil, Iván F.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. University of Helsinki, Finland.
    Berg, Peter
    Mogg, Andrew O. M.
    Westerbom, Mats
    Norkko, Alf
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. University of Helsinki, Finland.
    Glud, Ronnie N.
    Metabolism of a subtidal rocky mussel reef in a high-temperate setting: pathways of organic C flow2020In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 645, p. 41-54Article in journal (Refereed)
    Abstract [en]

    Mytilid mussels form abundant, species-rich reefs on rocky substrates, but the role of this key habitat in carbon (C) cycling remains poorly understood. We performed a seasonal study on a 5 m deep photic Mytilus trossulus reef in the Central Baltic Sea to investigate pathways and rates of organic C flow. Reef gross primary production (GPP) and respiration (R) were estimated seasonally using underwater O2 eddy covariance on hourly and daily timescales. Photogrammetry and biotic sampling were used to quantify reef rugosity and mussel coverage, and to derive mussel filtration and biodeposition. Mussels were highly abundant, reaching ~50000 ind. m-2, and the reef structure increased the seabed surface area by 44%. GPPhourly was up to 20 mmol O2 m-2 h-1 and GPPdaily was up to 107 mmol O2 m-2 d-1, comparable to a nearby seagrass canopy. Hourly eddy fluxes responded linearly to light intensity and flow velocity, with higher velocities enhancing reef O2 uptake at night. Reef Rdaily exceeded GPPdaily on 12 of 13 measurement days, and Rannual (29 mol O2 m-2 yr-1) was 3-fold larger than GPPannual. The reef sustained a productive community of microbes and fauna whose activities accounted for ~50% of Rannual. Horizontal water advection promoted food supply to the reef and likely facilitated substantial lateral C export of mussel biodeposits. Our analyses suggest that a reduction in mussel reef extent due to ongoing environmental change will have major implications for the transport and transformation of C and nutrients within the coastal Baltic Sea.

  • 24. Attard, Karl M.
    et al.
    Rodil, Iván F.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. University of Helsinki, Finland.
    Glud, Ronnie N.
    Berg, Peter
    Norkko, Joanna
    Norkko, Alf
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. University of Helsinki, Finland.
    Seasonal ecosystem metabolism across shallow benthic habitats measured by aquatic eddy covariance2019In: Limnology and Oceanography Letters, E-ISSN 2378-2242, Vol. 4, no 3, p. 79-86Article in journal (Refereed)
    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.

  • 25.
    Austin, Åsa N.
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Hansen, Joakim P.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Donadi, S.
    Bergström, U.
    Eriksson, B. K.
    Sundblad, G.
    Eklöf, Johan S.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Synergistic Effects of Rooted Aquatic Vegetation and Drift Wrack on Ecosystem Multifunctionality2021In: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 24, no 7, p. 1670-1686Article in journal (Refereed)
    Abstract [en]

    Ecosystem multifunctionality is an increasingly popular concept used to approximate multifaceted ecosystem functioning, which in turn may help advance ecosystem-based management. However, while experimental studies have shown a positive effect of diversity on multifunctionality, observational studies from natural systems-particularly aquatic-are scarce. Here, we tested the relative importance of species richness and cover of rooted aquatic vegetation, as well as cover of the loose-lying form of the macroalgae bladderwrack (Fucus vesiculosus), for ecosystem multifunctionality in shallow bays along the western Baltic Sea coast. We estimated multifunctionality based on four indicators of functions that support ecosystem services: recruitment of large predatory fish, grazer biomass, inverted 'nuisance' algal biomass, and water clarity. Piecewise path analysis showed that multifunctionality was driven by high cover of rooted aquatic vegetation and bladderwrack, particularly when the two co-occurred. This synergistic effect was nearly three times as strong as a negative effect of land-derived nitrogen loading. Species richness of aquatic vegetation indirectly benefitted multifunctionality by increasing vegetation cover. Meanwhile, high bladderwrack cover tended to decrease vegetation species richness, indicating that bladderwrack has both positive and negative effects on multifunctionality. We conclude that managing for dense and diverse vegetation assemblages may mitigate effects of anthropogenic pressures (for example, eutrophication) and support healthy coastal ecosystems that provide a range of benefits. To balance the exploitation of coastal ecosystems and maintain their multiple processes and services, management therefore needs to go beyond estimation of vegetation cover and consider the diversity and functional types of aquatic vegetation.

  • 26.
    Austin, Åsa N.
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Hansen, Joakim P.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Donadi, Serena
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Eklöf, Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Relationships between aquatic vegetation and water turbidity: A field survey across seasons and spatial scales2017In: PLOS ONE, E-ISSN 1932-6203, Vol. 12, no 8, article id e0181419Article in journal (Refereed)
    Abstract [en]

    Field surveys often show that high water turbidity limits cover of aquatic vegetation, while many small-scale experiments show that vegetation can reduce turbidity by decreasing water flow, stabilizing sediments, and competing with phytoplankton for nutrients. Here we bridged these two views by exploring the direction and strength of causal relationships between aquatic vegetation and turbidity across seasons (spring and late summer) and spatial scales (local and regional), using causal modeling based on data from a field survey along the central Swedish Baltic Sea coast. The two best-fitting regional-scale models both suggested that in spring, high cover of vegetation reduces water turbidity. In summer, the relationships differed between the two models; in the first model high vegetation cover reduced turbidity; while in the second model reduction of summer turbidity by high vegetation cover in spring had a positive effect on summer vegetation which suggests a positive feedback of vegetation on itself. Nitrogen load had a positive effect on turbidity in both seasons, which was comparable in strength to the effect of vegetation on turbidity. To assess whether the effect of vegetation was primarily caused by sediment stabilization or a reduction of phytoplankton, we also tested models where turbidity was replaced by phytoplankton fluorescence or sediment-driven turbidity. The best-fitting regional-scale models suggested that high sediment-driven turbidity in spring reduces vegetation cover in summer, which in turn has a negative effect on sediment-driven turbidity in summer, indicating a potential positive feedback of sediment-driven turbidity on itself. Using data at the local scale, few relationships were significant, likely due to the influence of unmeasured variables and/or spatial heterogeneity. In summary, causal modeling based on data from a large-scale field survey suggested that aquatic vegetation can reduce turbidity at regional scales, and that high vegetation cover vs. high sediment-driven turbidity may represent two self-enhancing, alternative states of shallow bay ecosystems.

  • 27.
    Austin, Åsa N.
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Hansen, Joakim P.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Donadi, Serena
    Kautsky, Lena
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Eklöf, Johan S.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Stronger effect of individual species’ traits than shading on aquatic plant community productivity and interspecific competition2023In: Aquatic Botany, ISSN 0304-3770, E-ISSN 1879-1522, Vol. 187, article id 103647Article in journal (Refereed)
    Abstract [en]

    Competition is one of the major factors structuring plant communities. Species with similar traits generally compete more intensely and have more similar yield than functionally dissimilar species, which often respond differently to environmental change. Little is known about how the interacting species’ traits influence the effect of environmental change on interspecific competition. However, theory predicts that environmental change should lead to more asymmetric competition, by favouring the species best adapted to the particular environmental change. Here we used a mesocosm experiment with three common aquatic plant species from the Baltic Sea (Northern Europe), to test how community productivity and competition asymmetry were affected by functional dissimilarity, individual species’ traits and a common stressor: shading. Competition asymmetry was defined as the absolute difference in reductions in yield relative to monocultures of two interacting species. Community productivity decreased and competition asymmetry increased with functional dissimilarity of the interacting species, possibly explained by the traits of the superior species, which had higher specific leaf area, maximum canopy height and primary production rate than the subordinate species. Community productivity was not affected by shading, contrary to our expectation, while competition asymmetry was higher in shaded than ambient conditions. Individual species yield depended on species identity and species combination. Only the shortest species was negatively affected by shading. Thus, by favouring tall-growing species, shading can alter interspecific competition. Together, these findings suggest that non-random species loss following environmental change can be caused by competitive exclusion, in addition to a direct effect of abiotic filtering.

  • 28. Barboza, Francisco R.
    et al.
    Kotta, Jonne
    Weinberger, Florian
    Jormalainen, Veijo
    Kraufvelin, Patrik
    Molis, Markus
    Schubert, Hendrik
    Pavia, Henrik
    Nylund, Göran M.
    Kautsky, Lena
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Schagerström, Ellen
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    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 gradient2019In: Ecology and Evolution, E-ISSN 2045-7758, Vol. 9, no 16, p. 9225-9238Article in journal (Refereed)
    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.

  • 29. Basirat, Farzad
    et al.
    Tsang, Chin-Fu
    Tatomir, Alexandru
    Guglielmi, Yves
    Dobson, Patrick
    Cook, Paul
    Dessirier, Benoit
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Juhlin, Christopher
    Niemi, Auli
    Hydraulic Modeling of Induced and Propagated Fractures: Analysis of Flow and Pressure Data From Hydromechanical Experiments in the COSC-1 Deep Borehole in Crystalline Rock Near Åre, Sweden2021In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 57, no 11, article id e2020WR029484Article in journal (Refereed)
    Abstract [en]

    To characterize the coupled hydromechanical behavior of rock fractures, the step-rate injection method for fracture in-situ properties (SIMFIP) was conducted with a specialized downhole probe developed by Guglielmi et al. (2014, https://doi.org/10.1007/s00603-013-0517-1). In June 2019, a field campaign was carried out near Åre, Sweden, where the SIMFIP probe was applied in the Collisional Orogeny in the Scandinavian Caledonides-1 scientific borehole to understand the dynamics of injection-induced fracture initiation, fracture opening, and shearing due to water injection-withdrawal in a borehole interval isolated by two packers. Three intervals were investigated at ∼500 m depth: (a) an unfractured section (intact rock), (b) a section with non-conductive fractures, and (c) a section with hydraulically conductive fractures. Pressure, injection flow rate, and borehole wall displacement were simultaneously measured during the tests. In the present study, the geometry of the induced fracture and deformation of existing fractures at different time stages of the tests are determined based on a hydrologic model by using the measured pressure and flow data during each time stage of the experiment. A numerical model for the fluid flow within the fracture and the packed-off borehole interval is implemented within COMSOL Multiphysics. By matching model simulations with observed data for all three sections, estimates of the induced and propagated fractures' radius and aperture at successive time stages have been obtained in each case. We could also determine the non-linear relationship between fracture aperture and pressure for values above fracture opening pressures. The model results provide insights for the understanding of pressure-induced fracture initiation and propagation in crystalline rock.

  • 30.
    Bauer, Barbara
    et al.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. Friedrich Schiller University Jena, Germany; German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Germany.
    Gustafsson, Bo G.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. University of Helsinki, Finland.
    Hyytiäinen, Kari
    Meier, H. E. Markus
    Müller-Karulis, Bärbel
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. Latvian Institute of Aquatic Ecology, Latvia.
    Saraiva, Sofia
    Tomczak, Maciej T.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Food web and fisheries in the future Baltic Sea2019In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 48, no 11, p. 1337-1349Article in journal (Refereed)
    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.

  • 31.
    Bauer, Barbara
    et al.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. German Centre for Integrative Biodiversity Research (iDiv), Germany.
    Horbowy, Jan
    Rahikainen, Mika
    Kulatska, Nataliia
    Müller-Karulis, Bärbel
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Tomczak, Maciej T.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Bartolino, Valerio
    Model uncertainty and simulated multispecies fisheries management advice in the Baltic Sea2019In: PLOS ONE, E-ISSN 1932-6203, Vol. 14, no 1, article id e0211320Article in journal (Refereed)
    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.

  • 32.
    Bauer, Barbara
    et al.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Meier, H. E. Markus
    Casini, Michele
    Hoff, Ayoe
    Margoński, Piotr
    Orio, Alessandro
    Saraiva, Sofia
    Steenbeek, Jeroen
    Tomczak, Maciej T.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Reducing eutrophication increases spatial extent of communities supporting commercial fisheries: a model case study2018In: ICES Journal of Marine Science, ISSN 1054-3139, E-ISSN 1095-9289, Vol. 75, no 4, p. 1306-1317Article in journal (Refereed)
    Abstract [en]

    In this study we investigate if eutrophication management has the potential to substantially affect which areas are going to be most suitable for commercial fishing in the future. We use a spatial ecosystem model, forced by a coupled physical-biogeochemical model, to simulate the spatial distribution of functional groups within a marine ecosystem, which depends on their respective tolerances to abiotic factors, trophic interactions, and fishing. We simulate the future long-term spatial developments of the community composition and their potential implications for fisheries under three different nutrient management scenarios and changing climate. The three nutrient management scenarios result in contrasting developments of bottom oxygen concentrations and phytoplankton abundance, with substantial effects on fish production. Nutrient load reduction increases the spatial extent of the areas suitable for the commercially most valuable demersal fish predator and all types of fisheries. This suggests that strategic planning of fishery management strategies could benefit from considering future changes in species distributions due to changes in eutrophication. We show that combining approaches from climate research, physical oceanography, biogeochemistry, biogeography, and trophic ecology with economical information provides a strong foundation to produce scientific knowledge that can support a multisectoral management of ecosystems.

  • 33.
    Bayer, Tina K.
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Gustafsson, Erik
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Brakebusch, Matthias
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Beer, Christian
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Future Carbon Emission From Boreal and Permafrost Lakes Are Sensitive to Catchment Organic Carbon Loads2019In: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 124, no 7, p. 1827-1848Article in journal (Refereed)
    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.

  • 34. Belgrano, Andrea
    et al.
    Novaglio, Camilla
    Svedäng, Henrik
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. University of Gothenburg, Sweden.
    Villasante, Sebastián
    Melián, Carlos J.
    Blenckner, Thorsten
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Bergström, Ulf
    Bryhn, Andreas
    Bergström, Lena
    Bartolino, Valerio
    Sköld, Mattias
    Tomczak, Maciej
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Wikström, Sofia A.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Skriver Hansen, Andreas
    Linke, Sebastian
    Emmerson, Richard
    Morf, Andrea
    Tönnesson, Kajsa
    Mapping and Evaluating Marine Protected Areas and Ecosystem Services: A Transdisciplinary Delphi Forecasting Process Framework2021In: Frontiers in Ecology and Evolution, E-ISSN 2296-701X, Vol. 9, article id 652492Article in journal (Refereed)
    Abstract [en]

    Marine Protected Areas (MPAs) are an important tool for management and conservation and play an increasingly recognised role in societal and human well-being. However, the assessment of MPAs often lacks a simultaneous consideration of ecological and socio-economic outcomes, and this can lead to misconceptions on the effectiveness of MPAs. In this perspective, we present a transdisciplinary approach based on the Delphi method for mapping and evaluating Marine Protected Areas for their ability to protect biodiversity while providing Ecosystem Services (ES) and related human well-being benefits - i.e., the ecosystem outputs from which people benefit. We highlight the need to include the human dimensions of marine protection in such assessments, given that the effectiveness of MPAs over time is conditional on the social, cultural and institutional contexts in which MPAs evolve. Our approach supports Ecosystem-Based Management and highlights the importance of MPAs in achieving restoration, conservation, and sustainable development objectives in relation to EU Directives such as the Marine Strategy Framework Directive (MSFD), the Maritime Spatial Planning Directive (MSPD), and the Common Fisheries Policy (CFP).

  • 35. Belgrano, Andrea
    et al.
    Tomczak, Maciej
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Wood, Daniel
    Working Group On Integrated Assessment of the North Sea (WGINOSE)2020Report (Other academic)
    Abstract [en]

    The Working Group on Integrated Assessment of the North Sea (WGINOSE) aims to provide a holistic analysis of the present and future status of the North Sea Ecosystem and human activities therein. Analyses are split among 14 strata since the North Sea is a diverse ecosystem spanning the shallows of the Southern North Sea banks to the deeps of the Norwegian Trench. State-ofthe-art statistical methods for trend analysis were performed on time-series data spanning 35 years (1984-2019) which show a flat (constant) or downward (declining) trend in all strata for cod, herring and haddock abundance, a consistent upward (rising) trend for temperature and dissolved oxygen, while other fish species and oceanographic variables show both upward, downward or flat trends.

  • 36. Berezina, Anfisa
    et al.
    Yakushev, Evgeniy
    Savchuk, Oleg
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Vogelsang, Christian
    Staalstrom, André
    Modelling the Influence from Biota and Organic Matter on the Transport Dynamics of Microplastics in the Water Column and Bottom Sediments in the Oslo Fjord2021In: Water, E-ISSN 2073-4441, Vol. 13, no 19, article id 2690Article in journal (Refereed)
    Abstract [en]

    The fate of microplastics (MP) in seawater is heavily influenced by the biota: the density of MP particles can be changed due to biofouling, which affects sinking, or MP can be digested by zooplankton and transferred into fecal pellets with increased sinking rate. We hypothesize that seasonal production and degradation of organic matter, and corresponding changes in the plankton ecosystem affect the MP capacity for transportation and burying in sediments in different seasons. This is simulated with a coupled hydrodynamical-biogeochemical model that provides a baseline scenario of the seasonal changes in the planktonic ecosystem and changes in the availability of particulate and dissolved organic matter. In this work, we use a biogeochemical model OxyDep that simulates seasonal changes of phytoplankton (PHY), zooplankton (HET), dissolved organic matter (DOM) and detritus (POM). A specifically designed MP module considers MP particles as free particles (MPfree), particles with biofouling (MPbiof), particles consumed by zooplankton (MPhet) and particles in detritus, including fecal pellets (MPdet). A 2D coupled benthic-pelagic vertical transport model 2DBP was applied to study the effect of seasonality on lateral transport of MP and its burying in the sediments. OxyDep and MP modules were coupled with 2DBP using Framework for Aquatic Biogeochemical Modelling (FABM). A depletion of MP from the surface water and acceleration of MP burying in summer period compared to the winter was simulated numerically. The calculations confirm the observations that the “biological pump” can be one of the important drivers controlling the quantity and the distribution of MP in the water column.

  • 37.
    Berggren, Hanna
    et al.
    Linnaeus University, Sweden.
    Tibblin, Petter
    Linnaeus University, Sweden.
    Yıldırım, Yeşerin
    Linnaeus University, Sweden.
    Broman, Elias
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Larsson, Per
    Linnaeus University, Sweden.
    Lundin, Daniel
    Linnaeus University, Sweden.
    Forsman, Anders
    Linnaeus University, Sweden.
    Fish Skin Microbiomes Are Highly Variable Among Individuals and Populations but Not Within Individuals2022In: Frontiers in Microbiology, E-ISSN 1664-302X, Vol. 12, article id 767770Article in journal (Refereed)
    Abstract [en]

    Fish skin-associated microbial communities are highly variable among populations and species and can impact host fitness. Still, the sources of variation in microbiome composition, and particularly how they vary among and within host individuals, have rarely been investigated. To tackle this issue, we explored patterns of variation in fish skin microbiomes across different spatial scales. We conducted replicate sampling of dorsal and ventral body sites of perch (Perca fluviatilis) from two populations and characterized the variation of fish skin-associated microbial communities with 16S rRNA gene metabarcoding. Results showed a high similarity of microbiome samples taken from the left and right side of the same fish individuals, suggesting that fish skin microbiomes can be reliably assessed and characterized even using a single sample from a specific body site. The microbiome composition of fish skin differed markedly from the bacterioplankton communities in the surrounding water and was highly variable among individuals. No ASV was present in all samples, and the most prevalent phyla, Actinobacteria, Bacteroidetes, and Proteobacteria, varied in relative abundance among fish hosts. Microbiome composition was both individual- and population specific, with most of the variation explained by individual host. At the individual level, we found no diversification in microbiome composition between dorsal and ventral body sites, but the degree of intra-individual heterogeneity varied among individuals. To identify how genetic and phenotypic characteristics of fish hosts impact the rate and nature of intra-individual temporal dynamics of the skin microbiome, and thereby contribute to the host-specific patterns documented here, remains an important task for future research.

     

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  • 38. Bergström, Lena
    et al.
    Fredriksson, Ronny
    Bergström, Ulf
    Rydin, Emil
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Kumblad, Linda
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Fish community responses to restoration of a eutrophic coastal bay2024In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 53, p. 109-125Article in journal (Refereed)
    Abstract [en]

    Interest in coastal restoration measures is increasing, but information about subsequent ecosystem recovery processes is limited. In Bjornofjarden on the Baltic Sea coast, Stockholm archipelago, a pioneering case study to reduce coastal eutrophication led to improvements and initially halved phosphorus levels. Here, we evaluate the effects of the restoration on the local fish assemblage over one decade after the measures. The study gives a unique possibility to evaluate responses of coastal fish to nutrient variables and abatement in a controlled natural setting. Cyprinid abundance decreased and perch partially increased with decreasing turbidity levels, while mean trophic level increased over time in the restored area. Responses were overall weak, likely attributed to an attenuation of the eutrophication abatement effect over time. The results suggest that nutrient reduction gives slow responses in fish compared to alternative measures such as fishing closures.

  • 39. Bergström, Lena
    et al.
    Kautsky, Lena
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Malm, Torleif
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Rosenberg, Rutger
    Wahlberg, Magnus
    Capetillo, Nastassja Åstrand
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Wilhelmsson, Dan
    Effects of offshore wind farms on marine wildlife-a generalized impact assessment2014In: Environmental Research Letters, E-ISSN 1748-9326, Vol. 9, no 3, p. 034012-Article in journal (Refereed)
    Abstract [en]

    Marine management plans over the world express high expectations to the development of offshore wind energy. This would obviously contribute to renewable energy production, but potential conflicts with other usages of the marine landscape, as well as conservation interests, are evident. The present study synthesizes the current state of understanding on the effects of offshore wind farms on marine wildlife, in order to identify general versus local conclusions in published studies. The results were translated into a generalized impact assessment for coastal waters in Sweden, which covers a range of salinity conditions from marine to nearly fresh waters. Hence, the conclusions are potentially applicable to marine planning situations in various aquatic ecosystems. The assessment considered impact with respect to temporal and spatial extent of the pressure, effect within each ecosystem component, and level of certainty. Research on the environmental effects of offshore wind farms has gone through a rapid maturation and learning process, with the bulk of knowledge being developed within the past ten years. The studies showed a high level of consensus with respect to the construction phase, indicating that potential impacts on marine life should be carefully considered in marine spatial planning. Potential impacts during the operational phase were more locally variable, and could be either negative or positive depending on biological conditions as well as prevailing management goals. There was paucity in studies on cumulative impacts and long-term effects on the food web, as well as on combined effects with other human activities, such as the fisheries. These aspects remain key open issues for a sustainable marine spatial planning.

  • 40.
    Bergström, Lena
    et al.
    Sveriges lantbruksuniversitet, Sverige.
    Wikström, Sofia A.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Halling, Christina
    Sveriges lantbruksuniversitet, Sverige.
    Biodiversitet och ekosystemtjänster i kustområden2021In: Biologisk mångfald, naturnyttor och ekosystemtjänster: Svenska perspektiv på livsviktiga framtidsfrågor / [ed] Håkan Tunón; Klas Sandell, Sveriges Lantbruksuniversitet, 2021, p. 209-219Chapter in book (Refereed)
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  • 41. Bergström, Ulf
    et al.
    Eklöf, Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Sköld, Mattias
    Hansen, Joakim P.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Wikström, Sofia
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Establish no-take zones to protect stocks and ecosystems2024Other (Other academic)
    Abstract [en]

    No-take zones can be an effective tool for protecting fish and crustacean stocks as well as marine ecosystems. However, it is important that these closed areas are properly designed and large enough. Seasonal spawning closures may be easier to enforce, but do not have as strong positive effects as no-take zones.

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    Policy brief: Establish no-take zones to protect stocks and ecosystems
  • 42. Bergström, Ulf
    et al.
    Eklöf, Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Sköld, Mattias
    Hansen, Joakim P.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Wikström, Sofia
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Berkström, Charlotte
    Inför fler fiskefria områden för att skydda bestånd och ekosystem2024Report (Other academic)
    Abstract [sv]

    Fiskefria områden kan vara ett effektivt verktyg för att skydda både fisk- och kräftdjursbestånd och marina ekosystem. Men det är viktigt att områdena utformas på rätt sätt och är tillräckligt stora. Lektidsfredade områden kan vara enklare att driva igenom, men ger inte lika goda effekter.

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  • 43. Bernard, Guillaume
    et al.
    Gammal, Johanna
    Järnström, Marie
    Norkko, Joanna
    Norkko, Alf
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. University of Helsinki, Finland.
    Quantifying bioturbation across coastal seascapes: Habitat characteristics modify effects of macrofaunal communities2019In: Journal of Sea Research, ISSN 1385-1101, E-ISSN 1873-1414, Vol. 152, article id 101766Article in journal (Refereed)
    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.

  • 44.
    Blenckner, Thorsten
    et al.
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Ammar, Yosr
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Müller-Karulis, Bärbel
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Niiranen, Susa
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Arneborg, Lars
    Li, Qiang
    Stockholm University, Faculty of Science, Department of Physical Geography.
    The Risk for Novel and Disappearing Environmental Conditions in the Baltic Sea2021In: Frontiers in Marine Science, E-ISSN 2296-7745, Vol. 8, article id 745722Article in journal (Refereed)
    Abstract [en]

    Future climate biogeochemical projections indicate large changes in the ocean with environmental conditions not experienced at present referred to as novel, or may even disappear. These climate-induced changes will most likely affect species distribution via changes in growth, behavior, evolution, dispersal, and species interactions. However, the future risk of novel and disappearing environmental conditions in the ocean is poorly understood, in particular for compound effects of climate and nutrient management changes. We map the compound risk of the occurrence of future novel and disappearing environmental conditions, analyze the outcome of climate and nutrient management scenarios for the world’s largest estuary, the Baltic Sea, and the potential consequences for three charismatic species. Overall, the future projections show, as expected, an increase in environmental novelty over time. The future nutrient reduction management that improves the eutrophication status of the Baltic Sea contributes to large novel and disappearing conditions. We show the consequences of novel and disappearing environmental conditions for fundamental niches of three charismatic species under different scenarios. This first step toward comprehensively analyzing environmental novelty and disappearing conditions for a marine system illustrates the urgent need to include novelty and disappearing projection outputs in Earth System Models. Our results further illustrate that adaptive management is needed to account for the emergence of novelty related to the interplay of multiple drivers. Overall, our analysis provides strong support for the expectation of novel ecological communities in marine systems, which may affect ecosystem services, and needs to be accounted for in sustainable future management plans of our oceans.

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  • 45.
    Blenckner, Thorsten
    et al.
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Möllmann, Christian
    Stewart Lowndes, Julia
    Griffiths, Jennifer R.
    Stockholm University, Faculty of Science, Stockholm Resilience Centre. Washington State Department of Fish and Wildlife, USA.
    Campbell, Eleanore
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    De Cervo, Andrea
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Belgrano, Andrea
    Boström, Christoffer
    Fleming, Vivi
    Frazier, Melanie
    Neuenfeldt, Stefan
    Niiranen, Susa
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Nilsson, Annika
    Ojaveer, Henn
    Olsson, Jens
    Palmlöv, Christine S.
    Stockholm University, Faculty of Science, Department of Environmental Science.
    Quaas, Martin
    Rickels, Wilfried
    Sobek, Anna
    Stockholm University, Faculty of Science, Department of Environmental Science.
    Viitasalo, Markku
    Wikström, Sofia A.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Halpern, Benjamin S.
    The Baltic Health Index (BHI): Assessing the social-ecological status of the Baltic Sea2021In: People and Nature, E-ISSN 2575-8314, Vol. 3, no 2, p. 359-375Article in journal (Refereed)
    Abstract [en]

    1. Improving the health of coastal and open sea marine ecosystems represents a substantial challenge for sustainable marine resource management, since it requires balancing human benefits and impacts on the ocean. This challenge is often exacerbated by incomplete knowledge and lack of tools that measure ocean and coastal ecosystem health in a way that allows consistent monitoring of progress towards predefined management targets. The lack of such tools often limits capabilities to enact and enforce effective governance.

    2. We introduce the Baltic Health Index (BHI) as a transparent, collaborative and repeatable assessment tool. The Index complements existing, more ecological-oriented, approaches by including a human dimension on the status of the Baltic Sea, an ecosystem impacted by multiple anthropogenic pressures and governed by a multitude of comprehensive national and international policies. Using a large amount of social-ecological data available, we assessed the health of the Baltic Sea for nine goals that represent the status towards set targets, for example, clean waters, biodiversity, food provision, natural products extraction and tourism.

    3. Our results indicate that the overall health of the Baltic Sea is suboptimal (a score of 76 out of 100), and a substantial effort is required to reach the management objectives and associated targets. Subregionally, the lowest BHI scores were measured for carbon storage, contaminants and lasting special places (i.e. marine protected areas), albeit with large spatial variation.

    4. Overall, the likely future status of all goals in the BHI averaged for the entire Baltic Sea is better than the present status, indicating a positive trend towards a healthier Baltic Sea. However, in some Baltic Sea basins, the trend for specific goals was decreasing, highlighting locations and issues that should be the focus of management priorities.

    5. The BHI outcomes can be used to identify both pan-Baltic and subregional scale management priorities and to illustrate the interconnectedness between goals linked by cumulative pressures. Hence, the information provided by the BHI tool and its further development will contribute towards the fulfilment of the UN Agenda 2030 and its Sustainability Development Goals.

  • 46.
    Bolinius, Dämien J.
    et al.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Sobek, Anna
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Löf, Marie F.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Undeman, Emma
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Evaluating the consumption of chemical products and articles as proxies for diffuse emissions to the environment2018In: Environmental Science: Processes & Impacts, ISSN 2050-7887, E-ISSN 2050-7895, Vol. 20, no 10, p. 1427-1440Article in journal (Refereed)
    Abstract [en]

    In this study we have evaluated the use of consumption of manufactured products (chemical products and articles) in the EU as proxies for diffuse emissions of chemicals to the environment. The content of chemical products is relatively well known. However, the content of articles (products defined by their shape rather than their composition) is less known and currently has to be estimated from chemicals that are known to occur in a small set of materials, such as plastics, that are part of the articles. Using trade and production data from Eurostat in combination with product composition data from a database on chemical content in materials (the Commodity Guide), we were able to calculate trends in the apparent consumption and in-use stocks for 768 chemicals in the EU for the period 2003-2016. The results showed that changes in the apparent consumption of these chemicals over time are smaller than in the consumption of corresponding products in which the chemicals are present. In general, our results suggest that little change in chemical consumption has occurred over the timespan studied, partly due to the financial crisis in 2008 which led to a sudden drop in the consumption, and partly due to the fact that each of the chemicals studied is present in a wide variety of products. Estimated in-use stocks of chemicals show an increasing trend over time, indicating that the mass of chemicals in articles in the EU, that could potentially be released to the environment, is increasing. The quantitative results from this study are associated with large uncertainties due to limitations of the available data. These limitations are highlighted in this study and further underline the current lack of transparency on chemicals in articles. Recommendations on how to address these limitations are also discussed.

  • 47.
    Bonaglia, Stefano
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. University of Southern Denmark, Denmark.
    Broman, Elias
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Brindefalk, Björn
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Hedlund, Erika
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Hjorth, Tomas
    Rolff, Carl
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Nascimento, Francisco J. A.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Udekwu, Klas
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Gunnarsson, Jonas S.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Activated carbon stimulates microbial diversity and PAH biodegradation under anaerobic conditions in oil-polluted sediments2020In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 248, article id 126023Article in journal (Refereed)
    Abstract [en]

    Biodegradation by microorganisms is a useful tool that helps alleviating hydrocarbon pollution in nature. Microbes are more efficient in degradation under aerobic than anaerobic conditions, but the majority of sediment by volume is generally anoxic. Incubation experiments were conducted to study the biodegradation potential of naphthalene-a common polycyclic aromatic hydrocarbon (PAH)-and the diversity of microbial communities in presence/absence of activated carbon (AC) under aerobic/anaerobic conditions. Radio-respirometry experiments with endogenous microorganisms indicated that degradation of naphthalene was strongly stimulated (96%) by the AC addition under anaerobic conditions. In aerobic conditions, however, AC had no effects on naphthalene biodegradation. Bioaugmentation tests with cultured microbial populations grown on naphthalene showed that AC further stimulated (92%) naphthalene degradation in anoxia. Analysis of the 16S rRNA gene sequences implied that sediment amendment with AC increased microbial community diversity and changed community structure. Moreover, the relative abundance of Geobacter, Thiobacillus, Sulfuricurvum, and methanogenic archaea increased sharply after amendment with AC under anaerobic conditions. These results may be explained by the fact that AC particles promoted direct interspecies electron transfer (DIET) between microorganisms involved in PAH degradation pathways. We suggest that important ecosystem functions mediated by microbes-such as hydrocarbon degradation-can be induced and that AC enrichment strategies can be exploited for facilitating bioremediation of anoxic oil-contaminated sediments and soils.

  • 48.
    Bonaglia, Stefano
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences. Lund University, Sweden.
    Klawonn, Isabell
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. IGB-Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Germany.
    De Brabandere, Loreto
    Deutsch, Barbara
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM). Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Thamdrup, Bo
    Brüchert, Volker
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Denitrification and DNRA at the Baltic Sea oxic-anoxic interface: Substrate spectrum and kinetics2016In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 61, no 5, p. 1900-1915Article in journal (Refereed)
    Abstract [en]

    The dependence of denitrification and dissimilatory nitrate reduction to ammonium (DNRA) on different electron donors was tested in the nitrate-containing layer immediately below the oxic-anoxic interface (OAI) at three stations in the central anoxic basins of the Baltic Sea. Additionally, pathways and rates of fixed nitrogen transformation were investigated with N-15 incubation techniques without addition of donors. Denitrification and anammox were always detected, but denitrification rates were higher than anammox rates. DNRA occurred at two sites and rates were two orders of magnitude lower than denitrification rates. Separate additions of dissolved organic carbon and sulfide stimulated rates without time lag indicating that both organotrophic and lithotrophic bacterial populations were simultaneously active and that they could carry out denitrification or DNRA. Manganese addition stimulated denitrification and DNRA at one station, but it is not clear whether this was due to a direct or indirect effect. Ammonium oxidation to nitrite was detected on one occasion. During denitrification, the production of nitrous oxide (N2O) was as important as dinitrogen (N-2) production. A high ratio of N2O to N-2 production at one site may be due to copper limitation, which inhibits the last denitrification step. These data demonstrate the coexistence of a range of oxidative and reductive nitrogen cycling processes at the Baltic OAI and suggest that the dominant electron donor supporting denitrification and DNRA is organic matter. Organotrophic denitrification is more important for nitrogen budgets than previously thought, but the large temporal variability in rates calls for long-term seasonal studies.

  • 49.
    Bonaglia, Stefano
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. University of Gothenburg, Sweden.
    Nascimento, Francisco J. A.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Meiofauna Shaping Biogeochemical Processes2023In: New Horizons in Meiobenthos Research: Profiles, Patterns and Potentials / [ed] Olav Giere; Michaela Schratzberger, Cham: Springer, 2023, p. 33-54Chapter in book (Refereed)
    Abstract [en]

    Biogeochemical processes at the sediment–water interface are essential for the functioning of marine ecosystems. It is a central question in benthic ecology how these processes are controlled and mediated by biotic factors. Particularly, the role of meiobenthos, the most abundant and diverse faunal component in these systems, is little understood and requires more attention. In this chapter, we discuss the impact of meiofauna bioturbation inmarine sediments on significant mechanisms and processes in (a) carbon degradation and oxygen penetration, (b) sulfide dynamics, and (c) nitrogen cycling. Particularly in the growing hypoxic areas of the seafloor where meiofauna is often the only animal group present, the role and bioturbative activities of this central component of the benthos need further scrutiny regarding the decrease of oxygen and increase of toxic hydrogen sulfide. These knowledge gaps in the interaction between meiofauna and marine biogeochemistry are the background for our concluding outlines: We present current research frontiers in order to assess the role of meiofauna as regulators of geochemical processes and microbial activities. These goals require combination of quantitative and qualitative meiobenthos investigations with state-of-the-art experimental work.

  • 50. Borg, Hans
    et al.
    Sundbom, Marcus
    Stockholm University, Faculty of Science, Department of Environmental Science. Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Long-term trends of water chemistry in mountain streams in northern Sweden – recovery from episodic acidification?2012Conference paper (Other academic)
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