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  • 251.
    Holmborn, Towe
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Dahlgren, Kristin
    Holeton, Claire
    Hogfors, Hedvig
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Gorokhova, Elena
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Biochemical proxies for growth and metabolism in Acartia bifilosa (Copepoda, Calanoida)2009In: Limnology and Oceanography: Methods, ISSN 1541-5856, E-ISSN 1541-5856, Vol. 7, p. 785-794Article in journal (Refereed)
    Abstract [en]

    Biochemical proxies are becoming increasingly common for growth assessment in zooplankton. Their suitability is often unknown, however, and proper calibration is lacking. We investigated correlations between physiological variables (ingestion, egg production, and respiration rates) and biochemical indices related to protein synthesis (RNA content, RNA:DNA ratio, RNA:protein ratio, and protein specific aminoacyl-tRNA synthetases [spAARS] activity) in copepods Acartia bifilosa exposed to different algal concentrations (0–1200 µg C L–1). All variables assayed increased with increasing food concentration either linearly (spAARS) or nonlinearly (all other variables). Egg production and ingestion rates were significantly and positively correlated with RNA content and RNA:protein ratio, whereas correlations with spAARS and RNA:DNA ratio were weaker or nonsignificant. However, when RNA:DNA ratio and spAARS activity were used as predictors of ingestion, together they had higher explanatory value than did either variable separately. As there were substantial differences in saturating food concentrations among the assayed variables, applicability of biomarkers as proxies of physiological rates will be more reliable if restricted to the nonsaturated phase of the functional response of either variable, unless both variables saturate simultaneously. These findings contribute to methodology of zooplankton growth assessment and to our understanding of biochemical processes underlying growth and metabolism in copepods.

  • 252.
    Holmborn, Towe
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Goetze, Erica
    University of Hawaii.
    Pollupuu, Maria
    University of Tartu.
    Pollumäe, Arno
    University of Tartu.
    Genetic species identification and low genetic diversity in Pseudocalanus acuspes of the Baltic Sea2011In: Journal of Plankton Research, ISSN 0142-7873, E-ISSN 1464-3774, Vol. 33, no 3, p. 507-515Article in journal (Refereed)
    Abstract [en]

    Calanoid copepods of the genus Pseudocalanus are key species in temperate-boreal marine pelagic ecosystems. Pseudocalanus species are difficult to distinguish morphologically and there is uncertainty regarding the species present in the Baltic Sea. In this study, we investigated the species composition of Pseudocalanus in the Baltic proper and the Gulf of Finland using a restriction fragment length polymorphism approach. Screening of 888 individuals from 13 different stations, sampled during various seasons on a total of 22 different occasions stretching from November 2006 until July 2008, confirmed that P. acuspes is the only Pseudocalanus species normally present in the Baltic Sea. Mitochondrial diversity is exceptionally low in Baltic Sea populations of P. acuspes, as only two cytochrome oxidase I haplotypes were observed in samples ranging from the Gulf of Finland in the north to the Arkona Basin in the south (83 individuals). This unusually low level of genetic diversity indicates that planktonic organisms may experience loss of genetic diversity in marginal Baltic Sea populations, despite large population sizes. Low genetic diversity may negatively impact the species' capacity for adaptation to environmental change.

  • 253.
    Holmborn, Towe
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Gorokhova, Elena
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Erratum to: Relationships between RNA content and egg production rate in Acartia bifilosa (Copepoda, Calanoida) of different spatial and temporal origin2008In: Marine Biology, ISSN 0025-3162, E-ISSN 1432-1793, Vol. 153, no 5, p. 1007-1008Article in journal (Refereed)
  • 254.
    Holmborn, Towe
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Gorokhova, Elena
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Relationships between RNA content and egg production rate in Acartia bifilosa (Copepoda, Calanoida) of different spatial and temporal origin2008In: MARINE BIOLOGY, ISSN 0025-3162, Vol. 153, no 3, p. 483-491Article in journal (Refereed)
    Abstract [en]

    To evaluate factors regulating RNA content (RNA, mu g RNA female(-1)) -egg production rate (EPR, eggs female(-1) day(-1)) relationship and to develop a model for in situ egg production rate estimates for Acartia bifilosa, we (1) measured EPR and RNA in females sampled at geographically distant areas at varying temperature (T, degrees C), (2) determined environmental (station, season, and T), endogenous (prosome length (PL), mm and EPR) variables that influence RNA levels, and (3) explored a set of multiple regression models to predict EPR from RNA, PL, station, season, and T. Egg production experiments were carried out in spring and summer 2005 in the Gulf of Finland and in the western part of the northern Baltic proper. We found that up to 88% of the RNA variation could be explained by variations in PL, EPR, and season/T. In explaining the RNA variability, PL played a major role followed in order of importance by EPR and season/T. Further, PL, RNA, and season/T explained up to 53% of the variation in EPR, nearly half of which is explained by RNA alone. The effect of spatial origin was never significant, suggesting that the derived relationships are general for A. bifilosa inhabiting northern Baltic proper.

  • 255.
    Hommersom, Annelies
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology. Water Insight, The Netherlands.
    Kratzer, Susanne
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Laanen, Marnix
    Ansko, Ilmar
    Ligi, Martin
    Bresciani, Mariano
    Giardino, Claudia
    Beltrán-Abaunza, José M.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Moore, Gerald
    Wernand, Marcel
    Peters, Steef
    Intercomparison in the field between the new WISP-3 and other radiometers (TriOS Ramses, ASD FieldSpec, and TACCS)2012In: Journal of Applied Remote Sensing, ISSN 1931-3195, E-ISSN 1931-3195, Vol. 6, article id 063615Article in journal (Refereed)
    Abstract [en]

    Optical close-range instruments can be applied to derive water quality parameters for monitoring purposes and for validation of optical satellite data. In situ radiometers are often difficult to deploy, especially from a small boat or a remote location. The water insight spectrometer (WISP-3) is a new hand-held radiometer for monitoring water quality, which automatically performs measurements with three radiometers (L-sky, L-u, E-d) and does not need to be connected with cables and electrical power during measurements. The instrument is described and its performance is assessed by an intercomparison to well-known radiometers, under real fieldwork conditions using a small boat and with sometimes windy and cloudy weather. Root mean squared percentage errors relative to those of the TriOS system were generally between 20% and 30% for remote sensing reflection, which was comparable to those of the other instruments included in this study. From this assessment, it can be stated that for the tested conditions, the WISP-3 can be used to obtain reflection spectra with accuracies in the same range as well-known instruments. When tuned with suitable regional algorithms, it can be used for quick scans for water quality monitoring of Chl, SPM, and aCDOM.

  • 256. Hopkins, Tom S.
    et al.
    Bailly, Denis
    Elmgren, Ragnar
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Glegg, Gillian
    Sandberg, Audun
    Stottrup, Josianne G.
    A Systems Approach Framework for the Transition to Sustainable Development: Potential Value Based on Coastal Experiments2012In: Ecology & society, ISSN 1708-3087, E-ISSN 1708-3087, Vol. 17, no 3, p. 39-Article in journal (Refereed)
    Abstract [en]

    This article explores the value of the Systems Approach Framework (SAF) as a tool for the transition to sustainable development in coastal zone systems, based on 18 study sites in Europe, where the SAF was developed and tested. The knowledge gained from these experiments concerns the practical aspects of (a) governance in terms of policy effectiveness, (b) sustainability science in terms of applying transdisciplinary science to social-ecological problems, and (c) simulation analysis in terms of quantifying dysfunctions in complex systems. This new knowledge can help broaden our perspectives on how research can be changed to better serve society. The infusion of systems thinking into research and policy making leads to a preference for multi-issue instead of single-issue studies, an expansion from static to dynamic indicators, an understanding of the boundaries between system-dependent and system-independent problems, and the inclusion of non-market evaluations. It also develops a real partnership among research, management, and stakeholders to establish a quantitative basis for collaborative decision making. Furthermore, the article argues that the transition to sustainable development for coastal systems requires consideration of the scale interdependency from individual to global and recognition of the probable global reorganizational emergence of scale-free networks that could cooperate to maximize the integrated sustainability among them.

  • 257. Hughes, TP
    et al.
    Bellwood, DR
    Folke, Carl
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    McCook, LJ
    Pandolfi, JM
    No-take areas, herbivory and coral reef resilience2007In: Trends in Ecology and Evolution, Vol. 22, no 1, p. 1-3Article in journal (Refereed)
  • 258. Hughes, TP
    et al.
    Gunderson, LH
    Folke, Carl
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Baird, AH
    Bellwood, D
    Berkes, F
    Crona, Beatrice
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Helfgott, A
    Leslie, H
    Norberg, Jon
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Nyström, Magnus
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Olsson, Per
    interfaculty units, Stockholm Resilience Centre.
    Österblom, Henrik
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Scheffer, M
    Schuttenberg, H
    Adaptive management of the Great Barrier Reef and the Grand Canyon world heritage areas2007In: Ambio, Vol. 36, no 7, p. 586-592Article in journal (Refereed)
  • 259.
    Humborg, Christoph
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Mörth, Carl-Magnus
    Department of Geology and Geochemistry.
    Sundbom, M.
    Wulff, Fredrik
    Department of Systems Ecology.
    Riverine transport of biogenic elements to the Baltic Sea: Past and possible future perspectives2007In: Hydrology and Earth System Science, Vol. 11, p. 1593-1607Article in journal (Refereed)
  • 260.
    Humborg, Christoph
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Mörth, C-M
    Sundbom, M
    Wulff, Fredrik
    Department of Systems Ecology.
    Riverine transport of biogenic elements to the Baltic Sea – past and possible future perspectives2007In: Hydrology and Earth System Sciences, Vol. 11, p. 1-15Article in journal (Refereed)
  • 261.
    Humborg, Christoph
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Smedberg, Erik
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Rodriguez Medina, Miguel
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Mörth, Carl-Magnus
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Changes in dissolved silicate loads to the Baltic Sea: The effects of lakes and reservoirs2008In: Journal of Marine Systems, ISSN 0924-7963, E-ISSN 1879-1573, Vol. 73, no 3-4, p. 223-235Article in journal (Refereed)
    Abstract [en]

    We tested the hypothesis that dissolved silicate (DSi) yields [kg km− 2 yr− 1] of 82 major watersheds of the Baltic Sea can be expressed as a function of the hydraulic load (HL) as a measure of water residence time and the total organic carbon (TOC) concentration, both variables potentially increasing the DSi yield. Most boreal rivers fitted a linear regression model using HL as an independent variable to explain the DSi yield. Rivers with high HL, i.e., shortest residence times, showed highest DSi yields up to 2300 kg km− 2 yr− 1. This is most likely caused by an excess supply of DSi, i.e., the geochemical sources prevail over biological sinks in these boreal watersheds. The DSi yield for regulated and unregulated larger rivers of the boreal watersheds constituting about 40% of the total water discharge and of the total DSi load to the Baltic Sea, respectively, can be expressed as: DSi yield = 190 + 49.5 HL[m yr− 1] + 0.346 TOC [µM] (R2 = 0.80). Since both HL and TOC concentrations have decreased after damming, the DSi yields have decreased significantly in the regulated boreal watersheds, for the River Luleälven we estimated more than 30%. The larger eutrophic watersheds draining cultivated landscape of the southern catchment of the Baltic Sea and representing about 50% of the annual water discharge to the Baltic Sea, deviated from this pattern and showed lower DSi yields between 60–580 kg km− 2 yr− 1. DSi yields showed saturation curve like relationship to HL and it appears that DSi is retained in the watersheds efficiently through biogenic silica (BSi) production and subsequent sedimentation along the entire river network. The relationship between HL and DSi yields for all larger cultivated watersheds was best fitted by a Freundlich isotherm (DSi = 115.7HL109; R2 = 0.73), because once lake and reservoir area exceeds 10% of the watershed area, minimum DSi yields were reached. To estimate an uperturbed DSi yield for the larger eutrophic southeastern watersheds is still difficult, since no unperturbed watersheds for comparison were available. However, a rough estimate indicate that the DSi flux from the cultivated watersheds to the Baltic Sea is nowadays only half the uperturbed flux. Overall, the riverine DSi loads to the Baltic Sea might have dropped with 30–40% during the last century.

  • 262.
    Höglander, Helena
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Hajdu, Susanna
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Skjevik, Ann-Turi
    SMHI, Swedish Meteorological and Hydrological Institute, Oceanographic Unit, Gothenburg.
    Andersson, Agneta
    Umeå Univeristy, Department of Ecology and Environmental Science.
    Karlsson, Chatarina
    Umeå University, Umeå Marine Sciences Centre.
    Pelagial biologi - växtplankton2012In: Havet: om miljötillståndet i i svenska havsområden, Stockholm: Naturvårdsverket , 2012, , p. 2p. 48-49Chapter in book (Other academic)
  • 263. Höök, T.O.
    et al.
    Gorokhova, E.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Hansson, S.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    RNA:DNA ratios of Baltic herring larvae and copepods in embayment and open sea habitats.2008In: ESTUARINE COASTAL AND SHELF SCIENCE, ISSN 0272-7714, Vol. 76, no 1, p. 29-35Article in journal (Refereed)
    Abstract [en]

    Elucidation of important nursery habitats for young fish can aid in the management and assessment of fish stocks. Herring (Clupea harengus) in the Baltic Sea primarily spawn in coastal areas, but larvae are also present in off-shore, open sea areas. To investigate if sheltered coastal habitats provide a better growth environment for larval herring, we compared short-term growth (as indexed by whole body RNA:DNA ratios) of larval herring from three habitat types of the northwest Baltic proper (sheltered inner bay, exposed outer bay, and open sea). In addition, we compared individual RNA content of adult female Eurytemora affinis (a common Baltic copepod) among these different habitats. High RNA levels in these copepods indicate high production of nauplii, which are important food for larval herring. Both RNA:DNA ratios of larval herring and RNA content of E. affinis were significantly greater in embayment habitats, suggesting that the sheltered coastal areas are high quality nursery habitats for young Baltic herring.

  • 264. Jaanus, A
    et al.
    Andersson, A
    Hajdu, Susanna
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Huseby, S
    Jurgenstone, I
    Olenina, I
    Wasmund, N
    Toming, K
    Shifts in the Baltic Sea summer phytoplankton communities in 1992-20062007Report (Other academic)
  • 265.
    Jaeschke, Benedict
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    The relative impact of the combined stresses hypoxia and ionising radiation in the marine bivalve, Mytilus edulisManuscript (preprint) (Other academic)
    Abstract [en]

    A key requirement to accurate risk assessment of the impact of radioactive materials in the environment is the ability to assess the interactions and combined effects of other existing stresses or contaminants. Hypoxia is a common and growing hazard in the world’s oceans. Hypoxia is known to cause radioresistance in tumorous tissues of patients undergoing radiotherapy, however the impacts of radiation on marine organisms exposed to hypoxia is largely untested. The hypoxia tolerant bivalve – the blue mussel, Mytilus edulis - was exposed to a range of doses of gamma radiation (0.04Gy – 4Gy), following acclimatisation to either normoxia (10mgoxygen.l-1) or moderate hypoxia (3mgoxygen.l-1). Oxidative stress (lipid peroxidation) and antioxidant enzyme (catalase and superoxide dismutase) analyses were performed on tissues taken from these mussels. Very little or no effects were observed resulting from irradiation regardless of oxic treatment, however large increases in oxidative stress and antioxidant response were observed in the tissues of mussels acclimatised to hypoxia. The results suggest that the mussels are more impacted by the moderate level of hypoxia than the high doses of radiation, indicating that the endpoints or the species is not sensitive to irradiation and that historical exposure has led to adapted responses to hypoxia.

  • 266.
    Jaeschke, Benedict C.
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Bradshaw, Clare
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Bioaccumulation of tritiated water in phytoplankton and trophic transfer of organically bound tritium to the blue mussel, Mytilus edulis2013In: Journal of Environmental Radioactivity, ISSN 0265-931X, E-ISSN 1879-1700, Vol. 115, p. 28-33Article in journal (Refereed)
    Abstract [en]

    Large releases of tritium are currently permitted in coastal areas due to assumptions that it rapidly disperses in the water and has a low toxicity due to its low energy emissions. This paper presents a laboratory experiment developed to identify previously untested scenarios where tritium may concentrate or transfer in biota relevant to Baltic coastal communities. Phytoplankton populations of Dunaliella tertiolecta and Nodularia spumigena were exposed at different growth-stages, to tritiated water (HTO; 10 MBq l(-1)). Tritiated D. tertiolecta was then fed to mussels, Mytilus edulis, regularly over a period of three weeks. Activity concentrations of phytoplankton and various tissues from the mussel were determined. Both phytoplankton species transformed HTO into organically-bound tritium (OBT) in their tissues. D. tertiolecta accumulated significantly more tritium when allowed to grow exponentially in HTO than if it had already reached the stationary growth phase; both treatments accumulated significantly more than the corresponding treatments of N. spumigena. No effect of growth phase on bioaccumulation of tritium was detectable in N. spumigena following exposure. After mussels were given 3 feeds of tritiated D. tertiolecta, significant levels of tritium were detected in the tissues. Incorporation into most mussel tissues appeared to follow a linear relationship with number of tritiated phytoplankton feeds with no equilibrium, highlighting the potential for biomagnification. Different rates of incorporation in species from a similar functional group highlight the difficulties in using a 'representative' species for modelling the transfer and impact of tritium. Accumulations of organic tritium into the mussel tissues from tritiated-phytoplankton demonstrate an environmentally relevant transfer pathway of tritium even when water-concentrations are reduced, adding weight to the assertion that organically bound tritium acts as a persistent organic pollutant. The persistence, potential for biomagnification and the increased toxicity of organic tritium increases the potential impact on the environment following a release of HTO; current legislation does not adequately take into account the nature of organic forms of tritium and therefore may be underestimating accumulation and toxic effect of tritium in the environment. Such information is necessary to accurately assess the distribution of tritium following routine releases, and to adequately protect the environment and humans.

  • 267.
    Jaeschke, Benedict
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Lind, Ole Christian
    University of Life Sciences (UMB), Norway.
    Bradshaw, Clare
    Stockholm University, Faculty of Science.
    Salbu, Brit
    University of Life Sciences (UMB), Norway .
    Retention of radioactive particles and associated effects in the filter-feeding marine mollusc Mytilus edulisManuscript (preprint) (Other academic)
    Abstract [en]

    Radioactive particles are aggregates of radioactive atoms formed by, e.g., condensation or precipitation of radionuclides or breakdown of larger radioactive materials, and can contain significant radioactivity. They have been released into the environment from nuclear weapons tests, and from accidents and effluents within the fuel nuclear cycle.

    Aquatic filter feeders can be expected to take up and potentially retain radioactive particles, which could then provide concentrated localised doses to nearby tissues. Despite the high potential for accumulation and the potency of radioactive exposure, studies of the retention of radioactive particles in filter feeders are scarce. This study experimentally investigated the retention and effects of radioactive particles in the blue mussel, Mytilus edulis.

    The spent fuel particles, collected in the field, comprised of a U and Al alloy containing fission products such as 137Cs and 90Sr/90Y. The particles were introduced into mussels in suspension with plankton food or through implantation under the mantle tissue. Induced effects of the particle exposure were measured using micronucleus and Comet assays on haemocytes. Of those particles introduced with food, 37.5 % were retained for 70 h, and were found in the siphons and gills, with the notable exception of one particle that was ingested, found in the stomach. Those not retained seemed to have been actively rejected by the mussels. In several cases where particles were retained or implanted, white marks suggesting necrosis were seen in the tissues near the particles; these are thought to be caused by radiation and physical irritation. The largest and most radioactive particle (estimated dose rate 3.18 ±0.06 Gy.h-1) caused the largest such mark in the mantle tissue; in this case, increased micronucleus frequency and Comet tail DNA % was also observed in the haemolymph collected from the muscle, implying that non-targeted effects of radiation were induced by the high dose particle.

    The results showed that radioactive particles can potentially be retained by blue mussels and retained high activity particles can potentially induce negative effects, particularly in tissues close to such particles. Thus, current methods which are used for risk assessment that calculate “no-effect dose” estimates and are based upon the absorbed dose equivalent limit are inadequate for radioactive particle exposures. In addition, knowledge is lacking about the ecological implications of radioactive particles, for example potential recycling within a population, or trophic transfer in the food chain.

  • 268.
    Jaeschke, Benedict
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Millward, Geoffrey E.
    Moody, A. John
    Jha, Awadhesh N.
    Tissue-specific incorporation and genotoxicity of different forms of tritium in the marine mussel, Mytilus edulis2011In: Environmental Pollution, ISSN 0269-7491, E-ISSN 1873-6424, Vol. 159, no 1, p. 274-280Article in journal (Refereed)
    Abstract [en]

    Marine mussels (Mytilus edulis) were exposed to seawater spiked with tritiated water (HTO) at a dose rate of 122 and 79 mu Gy h(-1) for 7 and 14 days, respectively, and tritiated glycine (T-Gly) at a dose rate of 4.9 mu Gy h(-1) over 7 days. This was followed by deputation in clean seawater for 21 days. Tissues (foot, gills, digestive gland, mantle, adductor muscle and byssus) and DNA extracts from tissues were analysed for their tritium activity concentrations. All tissues demonstrated bio-accumulation of tritium from HTO and T-Gly. Tritium from T-Gly showed increased incorporation into DNA compared to HTO. About 90% of the initial activity from HTO was depurated within one day, whereas T-Gly was depurated relatively slowly, indicating that tritium may be bound with different affinities in tissues. Both forms of tritium caused a significant induction of micronuclei in the haemocytes of mussels. Our findings identify significant differential impacts on Mytilus edulis of the two chemical forms of tritium and emphasise the need for a separate classification and control of releases of tritiated compounds, to adequately protect the marine ecosystem.

  • 269. James, P.
    et al.
    Tzoulas, K.
    Adams, M.D.
    Barber, A.
    Box, J.
    Breuste, J.
    Elmqvist, Thomas
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Frith, M.
    Gordon, C.
    Greening, K.L.
    Handley, J.
    Haworth, S.
    Kazmierczak, A.E.
    Johnston, M.
    Korpela, K.
    Moretti, M.
    Niemelä, J.
    Pauleit, S.
    Roe, M.H.
    Sadler, J.P.
    Ward Thompson, C.
    Towards an integrated understanding of green space in the European built environment2009In: Urban Forestry & Urban Greening, ISSN 1618-8667, E-ISSN 1610-8167, Vol. 8, no 2, p. 65-75Article in journal (Refereed)
    Abstract [en]

    In recent years social, economic and environmental considerations have led to a reevaluation of the factors that contribute to sustainable urban environments. Increasingly, urban green space is seen as an integral part of cities providing a range of services to both the people and the wildlife living in urban areas. With this recognition and resulting from the simultaneous provision of different services, there is a real need to identify a research framework in which to develop multidisciplinary and interdisciplinary research on urban green space. In order to address these needs, an iterative process based on the delphi technique was developed, which comprised email-mediated discussions and a two-day symposium involving experts from various disciplines. The two outputs of this iterative process were (i) an integrated framework for multidisciplinary and interdisciplinary research and (ii) a catalogue of key research questions in urban green space research. The integrated framework presented here includes relevant research areas (i.e. ecosystem services, drivers of change, pressures on urban green space, human processes and goals of provision of urban green space) and emergent research themes in urban green space studies (i.e. physicality, experience, valuation, management and governance). Collectively these two outputs have the potential to establish an international research agenda for urban green space, which can contribute to the better understanding of people's relationship with cities.

  • 270. Jensen, O. P.
    et al.
    Hansson, Sture
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Didrikas, T.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Stockwell, J. D.
    Hrabik, T. R.
    Axenrot, T.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Kitchell, J. F.
    Foraging, bioenergetic and predation constraints on diel vertical migration: field observations and modelling of reverse migration by young-of-the-year herring Clupea harengus2011In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 78, no 2, p. 449-465Article in journal (Refereed)
    Abstract [en]

    Diel vertical migration (DVM) of young-of-the-year (YOY) herring Clupea harengus and one of their major predators, pikeperch Sander lucioperca, was examined using bottom-mounted hydroacoustics in Himmerfjarden, a brackish bay of the Baltic Sea, in summer. In contrast to previous studies on DVM of C. harengus aggregated across size and age classes, YOY C. harengus showed a reverse DVM trajectory, deeper at night and, on average, shallower during the day. This pattern was observed consistently on five acoustic sampling occasions in 3 years and was corroborated by two out of three trawl surveys. Large acoustic targets (target strength >-33 dB, probably piscivorous S. lucioperca > 45 cm) showed a classic DVM trajectory, shallow at night and deeper during the day. Variability in YOY C. harengus vertical distribution peaked at dawn and dusk, and their vertical distribution at midday was distinctly bimodal. This reverse DVM pattern was consistent with bioenergetic model predictions for YOY C. harengus which have rapid gut evacuation rates and do not feed at night. Reverse DVM also resulted in low spatial overlap with predators.

  • 271.
    Johannesson, Kerstin
    et al.
    Göteborgs universitet.
    Hansson, Sture
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Hansson, Lars-Anders
    Lunds universitet.
    Eriksson, Lars-Ove
    Sveriges lantbruksuniversitet.
    Greenberg, Larry
    Karlstads universitet.
    Larsson, Per
    Kalmar universitet.
    Magnhagen, Carin
    Sveriges lantbruksuniversitet.
    Persson, Lennart
    Umeå universitet.
    Ulfstrand, Staffan
    Uppsala universitet.
    Ta med fisket i nya havsmyndigheten.2009In: Göteborgs-PostenArticle in journal (Other (popular science, discussion, etc.))
  • 272. Johansson, Siw
    et al.
    Wulff, Fredrik
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Bonsdorff, Erik
    The MARE Research Program 1999-2006 - Reflections on program management2007In: Ambio, Vol. 36, no 2, p. 119-122Article in journal (Other academic)
  • 273. Josefsson, Sarah
    et al.
    Leonardsson, Kjell
    Gunnarsson, Jonas S.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Wiberg, Karin
    Bioturbation-Driven Release of Buried PCBs and PBDEs from Different Depths in Contaminated Sediments2010In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 44, no 19, p. 7456-7464Article in journal (Refereed)
    Abstract [en]

    Bioturbation can remobilize previously buried contaminants, leading to an increased exposure of aquatic biota. The remobilization of buried polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) from three different sediment depth layers (2.0-2.5 cm, 5.0-5.5 cm, and 10.0-10.5 cm) was studied in a laboratory experiment with two benthic macrofauna species, the amphipod Monoporeia affinis and the polychaete Marenzelleria spp. Remobilization of PCBs and PBDEs was significantly higher in the presence of Marenzelleria spp. than in M. affinis treatments and controls (without macrofauna). The highest remobilization occurred from the most shallow layers (2.0-2.5 cm > 5.0-5.5 cm > 10.0-10.5 cm), but contaminants were remobilized due to bioturbation from layers down to at least 10 cm. Congeners with lower hydrophobicity were remobilized to a higher extent than more hydrophobic congeners. The contaminant distribution between the particulate and the dissolved phase in the water column depended on hydrophobicity and burial depth of the contaminant, with congeners from deeper layers displaying an increased distribution to the particulate phase. Release fluxes and sediment-to-water mass transfer coefficients (MTCs) show that bioturbation by the polychaete Marenzelleria spp. can lead to a significant remobilization of buried contaminants from Baltic Sea sediments.

  • 274. Josefsson, Sarah
    et al.
    Leonardsson, Kjell
    Gunnarsson, Jonas S.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Wiberg, Karin
    Influence of contaminant burial depth on the bioaccumulation of PCBs and PBDEs by two benthic invertebrates (Monoporeia affinis and Marenzelleria spp.)2011In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 85, no 9, p. 1444-1451Article in journal (Refereed)
    Abstract [en]

    The bioaccumulation of buried polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) added to specific depths in sediment (2.0-2.5, 5.0-5.5 and 10.0-10.5 cm) was studied in two infaunal species with similar feeding habits (surface deposit-feeders) but different bioturbation modes. The deep-burrowing polychaetes Marenzelleria spp. (Mz) displayed up to 36 times higher tissue concentrations of buried (spiked) contaminants than the surface-dwelling biodiffusing amphipod Monoporeia affinis. The differences in bioaccumulation were most pronounced for less hydrophobic contaminants due to the bioirrigating activity of Mz. Contaminants buried at shallow depths displayed higher accumulation than more deeply buried contaminants. In contrast, the bioaccumulation of unspiked (native) contaminants with a unifo vertical distribution in the sediment was similar between the species. For Mz, the BSAFs increased with increased K(ow) for the uniformly distributed contaminants, but decreased for the buried contaminants, which indicates that the dominant uptake routes of the buried contaminants can differ from the uniformly distributed contaminants. The surface sediment concentration of buried contaminants increased in Mz treatments, showing that Mz bioturbation can remobilize historically buried contaminants to the biologically active surface layer and increase the exposure for surface-dwelling species.

  • 275. Josefsson, Sarah
    et al.
    Schaanning, Morten
    Samuelsson, Göran S.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Gunnarsson, Jonas S.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Olofsson, Ida
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Eek, Espen
    Wiberg, Karin
    Capping Efficiency of Various Carbonaceous and Mineral Materials for In Situ Remediation of Polychlorinated Dibenzo-p-dioxin and Dibenzofuran Contaminated Marine Sediments: Sediment-to-Water Fluxes and Bioaccumulation in Boxcosm Tests2012In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 46, no 6, p. 3343-3351Article in journal (Refereed)
    Abstract [en]

    The efficiency of thin-layer capping in reducing sediment-to-water fluxes and bioaccumulation of polychlorinated dibenzo-p-dioxins and dibenzofurans, hexachlorobenzene, and octachlorostyrene was investigated in a boxcosm experiment. The influence of cap thickness (0.5-5 cm) and different cap materials was tested using a three-factor experimental design. The cap materials consisted of a passive material (coarse or fine limestone or a marine clay) and an active material (activated carbon (AC) or kraft lignin) to sequester the contaminants. The cap thickness and the type of active material were significant factors, whereas no statistically significant effects of the type of passive material were observed. Sediment-to-water fluxes and bioaccumulation by the two test species, the surface-dwelling Nassarius nitidus and the deep-burrowing Nereis spp., decreased with increased cap thickness and with addition of active material. Activated carbon was more efficient than lignin, and a similar to 90% reduction of fluxes and bioaccumulation was achieved with 3 cm caps with 3.3% AC. Small increases in fluxes with increased survival of Nereis spp. indicated that bioturbation by Nereis spp. affected the fluxes.

  • 276. Jungerstam, Jennifer
    et al.
    Erlandsson, Johan
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    McQuaid, Christopher D.
    Porri, Francesca
    Westerbom, Mats
    Kraufvelin, Patrik
    Is habitat amount important for biodiversity in rocky shore systems?: A study of South African mussel assemblages2014In: Marine Biology, ISSN 0025-3162, E-ISSN 1432-1793, Vol. 161, no 7, p. 1507-1519Article in journal (Refereed)
    Abstract [en]

    Habitat-forming species on rocky shores are often subject to high levels of exploitation, but the effects of subsequent habitat loss and fragmentation on associated species and the ecosystem as a whole are poorly understood. In this study, the effects of habitat amount on the fauna associated with mussel beds were investigated, testing for the existence of threshold effects at small landscape scales. Specifically, the relationships between mussel or algal habitat amount and: associated biodiversity, associated macrofaunal abundance and density of mussel recruits were studied at three sites (Kidd's Beach, Kayser's Beach and Kini Bay) on the southern and south-eastern coasts of South Africa. Samples, including mussel-associated macrofauna, of 10 x 10 cm were taken from areas with 100 % mussel cover (Perna perna or a combination of P. perna and Mytilus galloprovincialis) at each site. The amount of habitat provided by mussels and algae surrounding the sampled areas was thereafter determined at the 4.0 m(2) scale. A number of significant positive relationships were found between the amount of surrounding mussel habitat and the abundances of several taxa (Anthozoa, Malacostraca and Nemertea). Likewise, there were positive relationships between the amount of surrounding algal habitat and total animal abundance as well as abundance of mussel recruits at one site, Kini Bay. In contrast, abundance of mussel recruits showed a significant negative relationship with the amount of mussel habitat at Kayser's Beach. Significant negative relationships were also detected between the amount of mussel habitat and species richness and total abundance at Kidd's Beach, and between amount of mussel habitat and the abundance of many taxa (Bivalvia, Gastropoda, Maxillopoda, Ophiuroidea, Polychaeta and Pycnogonida) at all three sites. No threshold effects were found, nor were significant relationships consistent across the investigated sites. The results indicate that the surrounding landscape is important in shaping the structure of communities associated with these mussel beds, with significant effects of the amount of surrounding habitat per se. The strength and the direction of habitat effects vary, however, between shores and probably with the scale of observation as well as with the studied dependent variables (e.g. diversity, abundance, mussel recruitment, species identity), indicating the complexity of the processes structuring macrofaunal communities on these shores.

  • 277. Järemo, J.
    et al.
    Almqvist, G.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    The effects of propagule pressure and age-specific alterations in demographic parameters on the establishment of the round goby in the Baltic Sea.Manuscript (Other academic)
  • 278.
    Kadin, Martina
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Man, murres and modern fisheries: A case study in the Baltic Sea2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Overfishing and climate change put increasing pressure on marine systems, with effects on commercially targeted fish and top predators dependent on these resources. To achieve sustainable resource use, governance mechanisms need to incorporate knowledge about ecosystem dynamics. Another key for success is the perception among actors about the challenges oceans are facing. Seabirds have become well-known symbols of coasts and oceans and their struggles with the consequences of human actions provide an illustration of the need to properly govern marine resources. Seabirds can be useful indicators of states of marine systems, forming tools that can help informing ecosystem approaches to management. The thesis focuses on the piscivorous seabird the common murre Uria aalge in the Baltic Sea, investigating two different aspects of interactions between seabirds and fisheries. In paper I, the effects of food quality and quantity during the chick-rearing period were investigated. Food quality (sprat Sprattus sprattus weight-at-age), but not quantity (sprat abundance), was positively related to murre fledging success. The adjustments of parental effort in relation to quality and quantity showed the opposite pattern – no relationships between parental effort and sprat weight-at-age but a negative relationship between sprat abundance and the duration of foraging trips. Paper II uses a long-term ring recovery dataset to study murre bycatch in Baltic Sea fisheries. We found an increase in the proportion bycatch between 1972 and 2008, and a strong bimodal intraannual pattern in bycatches, with peaks in spring and autumn, similar in three investigated periods. Uncertain finding dates were common and could potentially affect conclusions about intraannual patterns. Reported bycatches were concentrated to waters around the Hel peninsula, Poland. In recent years, 2000-2008, an increase of reported bycatch could be observed in the southeastern parts of the Baltic Sea. The findings of this thesis can aid the selection and interpretation of indicators for ecosystem approaches to Baltic Sea fisheries management, and further be used to communicate the need for such approaches.

  • 279. Kahru, Matti
    et al.
    Savchuk, Oleg
    Stockholm University, Faculty of Science, Department of Systems Ecology. marin ekologi.
    Elmgren, Ragnar
    Stockholm University, Faculty of Science, Department of Systems Ecology. marin ekologi.
    Satellite measurements of cyanobacterial bloom frequency in the Baltic Sea: interannual and spatial variability2007In: Marine Ecology Progress Series, Vol. 343, p. 15-23Article in journal (Refereed)
  • 280.
    Karlson, Agnes
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Almqvist, Gustaf
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Skóra, KE
    Appelberg, Magnus
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Indications of competition between non-indigenous round goby and native flounder in the Baltic Sea2007In: ICES Journal of Marine Science, Vol. 64, no 3, p. 479-486Article in journal (Refereed)
  • 281.
    Karlson, Agnes M. L.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Benthic use of phytoplankton blooms: uptake, burial and biodiversity effects in a species-poor system2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Animals living in marine sediments (the second largest habitat on earth) play a major role in global biogeochemical cycling. By feeding on organic matter from settled phytoplankton blooms they produce food for higher trophic levels and nutrients that can fuel primary production. In the Baltic Sea, anthropogenic stresses, such as eutrophication and introductions of invasive species, have altered phytoplankton dynamics and benthic communities. This thesis discusses the effects of different types of phytoplankton on the deposit-feeding community and the importance of benthic biodiversity for fate of the phytoplankton bloom-derived organic matter.

    Deposit-feeders survived and fed on settled cyanobacterial bloom material and in doing so accumulated the cyanobacterial toxin nodularin. Their growth after feeding on cyanobacteria was much slower than on a diet of spring bloom diatoms. The results show that settling blooms of cyanobacteria are used as food without obvious toxic effects, although they do not sustain rapid growth of the fauna. Since all tested species accumulated the cyanotoxin, negative effects higher up in the food web can not be ruled out. Both species composition and richness of deposit-feeding macrofauna influenced how much of the phytoplankton bloom material that was incorporated in fauna or retained in the sediment. The mechanism behind the positive effect of species richness was mainly niche differentiation among functionally different species, resulting in a more efficient utilization of resources at greater biodiversity. This was observed even after addition of an invasive polychaete species. Hence, species loss can be expected to affect benthic productivity negatively. In conclusion, efficiency in organic matter processing depends both on pelagic phytoplankton quality and benthic community composition and species richness.

  • 282.
    Karlson, Agnes M. L.
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Mozuraitis, Raimondas
    Deposit-feeders accumulate the cyanobacterial toxin nodularin2011In: Harmful Algae, ISSN 1568-9883, E-ISSN 1878-1470, Vol. 12, p. 77-81Article in journal (Refereed)
    Abstract [en]

    Blooms of toxic cyanobacteria may potentially affect food web productivity and even be a human health hazard. In the Baltic Sea, regularly occurring summer blooms of nitrogen-fixing cyanobacteria are often dominated by Nodularia spumigena, which produces the potent hepatotoxin nodularin. Evidence of sedimentation of these blooms indicates that benthic fauna can be exposed to nodularin. In a one month experiment, we simulated the settling of a summer bloom dominated by N. spumigena in sediment microcosms with three species of sediment-dwelling, deposit-feeding macrofauna, the amphipods Monoporeia affinis and Pontoporeia femorata and the bivalve Macoma balthica, and analyzed nodularin in the animals by HPLC-ESI-MS (high-performance liquid chromatography-electrospray ionization-mass spectrometry). We found nodularin in quantities of 50-120 ng g(-1) DW. The results show that deposit-feeding macrofauna in the Baltic Sea may contribute to trophic transfer of nodularin.

  • 283.
    Karlson, Agnes M. L.
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Nascimento, Francisco J. A.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Näslund, Johan
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Elmgren, Ragnar
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Higher diversity of deposit-feeding macrofauna enhances phytodetritus processing2010In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 91, no 5, p. 1414-1423Article in journal (Refereed)
    Abstract [en]

    The link between biodiversity and ecosystem functioning is an important question that remains unresolved, particularly in marine systems, in which cycling of organic matter by benthic organisms is of global significance. Direct observations of specific resource use by each species in single- and multispecies communities, as quantified by stable isotopes, facilitates a mechanistic understanding of the importance of each species for ecosystem functioning. We tested the effects of altered biodiversity (species richness) of deposit-feeding macrofauna on incorporation and burial of phytodetritus in combinations of three species representing natural communities found in the sediments of the species-poor Baltic Sea. The three species, two amphipods and a bivalve, had different rates of incorporation and burial and different needs for carbon (C) and nitrogen (N). The amphipods exhibited clear resource partitioning in sympatry, as a result of vertical separation in the sediment and consequent differential use of food. Communities of several species incorporated more C and N than expected from the respective single-species treatments, due to higher incorporation by surface feeders in multispecies treatments. Community incorporation of N in the most diverse treatment even exceeded N incorporation by a single-species treatment of the best-performing species, showing transgressive over-yielding. This over-yielding was primarily due to positive complementarity in all treatments. Diverse soft bottoms are also likely to be more productive in the long run, as species-specific traits (subsurface feeding) preserve fresh phytodetritus by burying it to depths in the sediment at which the mineralization rate is low. The more diverse sediment communities showed more efficient trophic transfer of phytodetritus, a finding of general significance for understanding biological processes driving the transformation of nutrients and energy in benthic ecosystems.

  • 284.
    Karlson, Agnes M. L.
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Nascimento, Francisco J. A.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Sanna, Suikkanen
    Elmgren, Ragnar
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Benthic fauna affects recruitment from sediments of the harmful cyano­bacterium Nodularia spumigena 2012In: Harmful Algae, ISSN 1568-9883, E-ISSN 1878-1470, Vol. 20, p. 126-131Article in journal (Refereed)
    Abstract [en]

    Physical disturbance and feeding by macrofauna in the sediment can potentially affect bloom initiation of phytoplankton species that have benthic stages in their life cycle. In this experimental study, we investigated how different species of macrozoobenthos can affect the recruitment of Nodularia spumigena from the sediment to the water column. N. spumigena is a toxic, nitrogen-fixing filamentous cyanobacterium, which forms large summer blooms in the Baltic Sea. Benthic recruitment from resting stages (akinetes) and vegetative cells deposited on the seafloor have long been suspected to initiate the blooms. We found that, depending on species-specific traits, deposit-feeding macrofauna (an amphipod, Monoporeia affinis, a bivalve, Macoma balthica and an invasive polychaete, Marenzelleria cf. arctia) has the potential to either reduce or facilitate recruitment of this cyanobacterium. Shorter filament length in treatments with fauna than in the treatment without indicates feeding on or mechanical destruction of N. spumigena by the animals. Our results show the importance of an often overlooked aspect of phytoplankton bloom initiation, the role of macrozoobenthos.

  • 285.
    Karlson, Agnes M. L.
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Näslund, Johan
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Ryden, Sara Blomgren
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Elmgren, Ragnar
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Polychaete invader enhances resource utilization in a species-poor system2011In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 166, no 4, p. 1055-1065Article in journal (Refereed)
    Abstract [en]

    Ecosystem consequences of biodiversity change are often studied from a species loss perspective, while the effects of invasive species on ecosystem functions are rarely quantified. In this experimental study, we used isotope tracers to measure the incorporation and burial of carbon and nitrogen from a simulated spring phytoplankton bloom by communities of one to four species of deposit-feeding macrofauna found in the species-poor Baltic Sea. The recently invading polychaete Marenzelleria arctia, which has spread throughout the Baltic Sea, grows more rapidly than the native species Monoporeia affinis, Pontoporeia femorata (both amphipods) and Macoma balthica (a bivalve), resulting in higher biomass increase (biomass production) in treatments including the polychaete. Marenzelleria incorporated and buried bloom material at rates similar to the native species. Multi-species treatments generally had higher isotope incorporation, indicative of utilization of bloom material, than expected from monoculture yields of the respective species. The mechanism behind this observed over-yielding was mainly niche complementarity in utilization of the bloom input, and was more evident in communities including the invader. In contrast, multi-species treatments had generally lower biomass increase than expected. This contrasting pattern suggests that there is little overlap in resource use of freshly deposited bloom material between Marenzelleria and the native species but it is likely that interference competition acts to dampen resulting community biomass. In conclusion, an invasive species can enhance incorporation and burial of organic matter from settled phytoplankton blooms, two processes fundamental for marine productivity.

  • 286.
    Karlson, Agnes M. L.
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Viitasalo-Frösen, Satu
    Finnish institute of marine research.
    Assimilation of 14C-labelled zooplankton benthic eggs by macrobenthos2009In: Journal of Plankton Research, ISSN 0142-7873, E-ISSN 1464-3774, Vol. 31, no 4, p. 459-463Article in journal (Refereed)
  • 287.
    Karlson, Agnes M.L.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Benthic-pelagic coupling in the northern Baltic Sea: the link between settling cyanobacterial blooms and macrobenthos.2008Licentiate thesis, monograph (Other academic)
  • 288.
    Karlson, Agnes
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Nascimento, Francisco
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Elmgren, Ragnar
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Incorporation and burial of carbon from settling cyanobacterial blooms by deposit-feeding macrofauna2008In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 53, no 6, p. 2754-2758Article in journal (Refereed)
    Abstract [en]

    Summer blooms of filamentous, nitrogen-fixing cyanobacteria are typical of the Baltic Sea, and recent findings indicate that cyanobacteria may be an important food source for the benthos below the euphotic zone. In a 2-week laboratory experiment, we measured incorporation of cyanobacterial carbon by the deposit-feeding amphipod Monoporeia affinis when exposed to 14C-radiolabeled, natural blooms of cyanobacteria dominated by either the toxic Nodularia spumigena or non-toxic Aphanizomenon sp. Carbon from both cyanobacterial blooms was used, with greater incorporation from Aphanizomenon-dominated bloom material than from N. spumigena, indicating that the latter is less suitable as food. However, neither cyanobacterium supported significant amphipod growth. Also, less cyanobacterial carbon was mixed down in the sediment in the N. spumigena treatment, indicating lower bioturbation activity in this treatment. Long-term effects on feeding and survival remain to be studied, especially for the toxic N. spumigena.

  • 289.
    Karlson, Agnes
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Näslund, Johan
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Blomgren Rydén, Sara
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Effects of a polychaete invader on soft-bottom ecosystem functionsManuscript (preprint) (Other academic)
  • 290. Karlsson, A. M. L.
    et al.
    Almqvist, G.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Skóra, K. E.
    Appelberg, M.
    Indications of competition between non-indigenous round goby and native flounder in the Baltic Sea.2007In: ICES Journal of Marine Science, Vol. 64, p. 479 - 486Article in journal (Refereed)
  • 291.
    Kautsky, Hans
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Wallin, Anders
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Nyström Sandman, Antonia
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Qvarfordt, Susanne
    Improvement of Baltic Sea coastal ecosystems indicated by increased distribution of Fucus vesiculosus L. since 1984Manuscript (preprint) (Other academic)
    Abstract [en]

    Although there are several reports of continued eutrophication in the open Baltic Sea, we found increased distribution and depth penetration of Fucus vesiculosus in the coastal, phytobenthic system, indicating recovery. After a decline in depth penetration of Fucus in the Åland Sea by 3 m, from a maximum of 11.5 m in the 1940s to 8.5 m in 1984, the Fucus plants had again increased their depth distribution in 1992 and 1996, and in 2006 being back to the depths of the 1940s. Also, in the Askö area, data from the national monitoring programme show an increase of the Fucus maximum depth by 1 m between 1993 and 2009. We used Generalized Additive Models (GAM) to predict the change in percent cover of Fucus in the Askö area from 1993 to 2009. The largest change in Fucus coverage was predicted to occur in the inner parts of the archipelago, decreasing further out, thus being related to reductions in nutrient inputs from land sources. The field data however, showed the largest changes in the middle part since coverage and depth penetration of Fucus in the inner parts are limited by the quick change with depth from hard to soft substrates. In the Askö area the results in the inner archipelago could be linked to an increase in the spring Secchi depth since the beginning of the 1990s. The Secchi depth change was in accordance with the trends of decreasing spring primary production and chlorophyll-a concentration. As the most pronounced change in Secchi depth during the time period was a decrease in July and August, the summer conditions seem to have little influence on the depth distribution of Fucus.

  • 292. Klais, Riina
    et al.
    Tamminen, Timo
    Kremp, Anke
    Spilling, Kristian
    An, Byoung Woong
    Hajdu, Susanna
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Olli, Kalle
    Spring phytoplankton communities shaped by interannual weather variability and dispersal limitation: Mechanisms of climate change effects on key coastal primary producers2013In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 58, no 2, p. 753-762Article in journal (Refereed)
    Abstract [en]

    Spring bloom composition in the Baltic Sea, a partially ice-covered brackish coastal waterbody, is shaped by winter-spring weather conditions affecting the relative dominance of diatoms and a heterogeneous assemblage of cold-water dinoflagellates, dominated by the chain-forming Peridiniella catenata and a complex of at least three medium-sized, single-celled species: Biecheleria baltica, Gymnodinium corollarium, and Scrippsiella hangoei. During the last decades, the bloom community has dramatically changed in several basins. We analyze here a 30 yr time series of quantitative phytoplankton data, as predicted by hindcast modeled ice thickness and storminess for three distinct Baltic Sea localities, to verify climate-driven mechanisms affecting the spring bloom composition. Thick (> 30 cm) and long-lasting ice cover favored diatom-dominated spring blooms, and mild winters, with storms and thin ice cover (10 to 20 cm), supported blooms of the B. baltica complex. Dispersal limitation plays an important role in the spatial extent of blooms of the B. baltica complex, caused by intricate interplay of local hydrodynamics and the dinoflagellate life cycle. Proportion peaks of key phytoplankton groups have shifted about 10 d earlier in the northwestern Baltic Sea (P. catenata and diatoms) and in the Gulf of Riga (P. catenata). The significant weather effects imply future shifts in spring bloom composition and consequent biogeochemical cycles, driven by the predicted changes in winter storminess and decrease in ice cover extent and duration in climate change models.

  • 293. Knudby, Anders
    et al.
    Nordlund, Lina
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Remote sensing of seagrasses in a patchy multi-species environment2011In: International Journal of Remote Sensing, ISSN 0143-1161, E-ISSN 1366-5901, Vol. 32, no 8, p. 2227-2244Article in journal (Refereed)
    Abstract [en]

    We tested the utility of IKONOS satellite imagery to map seagrass distribution and biomass in a 4.1 km2 area around Chumbe Island, Zanzibar, Tanzania. Considered to be a challenging environment to map, this area is characterized by a diverse mix of inter- and subtidal habitat types. Our mapped distribution of seagrasses corresponded well to field data, although the total seagrass area was underestimated due to spectral confusion and misclassification of areas with sparse seagrass patches as sparse coral and algae-covered limestone rock. Seagrass biomass was also accurately estimated (r2 = 0.83), except in areas with Thalassodendron ciliatum (r2 = 0.57), as the stems of T. ciliatum change the relationship between light interception and biomass from that of other species in the area. We recommend the use of remote sensing over field-based methods for seagrass mapping because of the comprehensive coverage, high accuracy and ability to estimate biomass. The results obtained with IKONOS imagery in our complex study area are encouraging, and support the use of this data source for seagrass mapping in similar areas.

  • 294.
    Konovalenko, Lena
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Element transport in marine coastal ecosystems – modelling general and element-specific mechanisms2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Understanding the behaviour of naturally-occurring and anthropogenically-derived radionuclides (isotopes) in the marine environment is important, because there is a need for their effective utilization either as in situ tracers or for industry, medical applications, the planning of waste-disposal facilities, and estimations of human and animal health risks. Radionuclides generally have the same chemical properties as their stable element analogues and thus show similar environmental behaviour and cycling to their stable counterparts. However, they are distinguished by potentially enhanced impacts on organisms due to their radioactivity emitted as alpha, beta or gamma radiation. There are many nuclear facilities, such as power reactors, research reactors, waste handling facilities and fuel production facilities located in the drainage area of the Baltic Sea which discharge directly or indirectly into the Baltic Sea. Thus knowledge about factors and processes in space and time that control the fate of radionuclides in the aquatic ecosystem provide the basis for dose and risk assessment for human and biota. Radionuclides’ stable analogues are often elements that have numerous industrial applications and are used widely in society (e.g., metals, rare earth metals). These are often released in aquatic environments and can be toxic. Consequently, they also require better control in order to protect the environment from pollution and provide quick responses in case of accidents. Understanding how such elements are distributed in the freshwater, seawater, sediments and aquatic organisms is therefore important. Modelling is a useful approach for the estimation of possible element concentrations and inventories in the aquatic ecosystem.

    In this thesis a dynamic stochastic compartment model (K-model) for radionuclide transfer in a marine coastal ecosystem was implemented for a coastal area in Öregrundsgrepen, Baltic Sea, Sweden, in order to determine the fate of radionuclides released in the sea water (Paper I). Radionuclide-specific mechanisms such as radionuclide uptake via diet and adsorption of radionuclides to organic surfaces were connected to the ecosystem model. Using the model, we estimated concentration ratios (CR; the ratio of the radionuclide concentration in an organism to the concentration in water) in the ecosystem and compared these with measured data for grazers, benthos, zooplankton and fish for 26 elements. The uncertainty variations of CRs were reduced when the model was parameterised with site data and elements with higher sorption capacity had higher CRs for all organism groups. The K-model was also validated with a 3D hydrodynamic spatial model (D-model) (Paper II). Despite differences in temporal resolution, biological state variables and partition coefficients, the accumulation of Th-230, Cs-135 and Ni-59 in biological compartments was comparable between the models and with site measurements. Both models provided confidence limits for their modelled concentration ratios, an improvement over models that only estimate mean values. The models developed here are useful tools for assessing the degree to which organisms can be affected by the distribution and fate of pollutants in the marine environment.

     

  • 295. Krasny, Marianne E.
    et al.
    Russ, Alex
    Tidball, Keith G.
    Elmqvist, Thomas
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Civic ecology practices: Participatory approaches to generating and measuring ecosystem services in cities2014In: Ecosystem Services, ISSN 2212-0416, E-ISSN 2212-0416, Vol. 7, p. 177-186Article in journal (Refereed)
    Abstract [en]

    Civic ecology practices are community based, environmental stewardship actions taken to enhance green infrastructure, ecosystem services, and human well-being in cities and other human-dominated landscapes. Examples include tree planting in post-Katrina New Orleans, oyster restoration in New York City, community gardening in Detroit, friends of parks groups in Seattle, and natural area restoration in Cape Flats, South Africa. Whereas civic ecology practices are growing in number and represent a participatory approach to management and knowledge production as called for by global sustainability initiatives, only rarely are their contributions to ecosystem services measured. In this paper, we draw On literature sources and our prior research in urban social-ecological systems to explore protocols for monitoring biodiversity, functional measures of ecosystem services, and ecosystem services valuation that can be adapted for use by practitioner-scientist partnerships in civic ecology settings. Engaging civic ecology stewards in collecting such measurements presents opportunities to gather data that can be used as feedback in an adaptive co-management process. Further, we suggest that civic ecology practices not only create green infrastructure that produces ecosystem services, but also constitute social-ecological processes that directly generate ecosystem services (e.g., recreation, education) and associated benefits to human well-being.

  • 296.
    Kratzer, Susanne
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology. Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Tett, Paul
    Using bio-optics to investigate the extent of coastal waters: A Swedish case study2009In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 629, no 1, p. 169-186Article in journal (Refereed)
    Abstract [en]

    In order to develop an optical model to map the extent of coastal waters, the authors analyzed variations in bio-optical constituents and submarine optical properties along a transect from the nutrient-enriched coastal bay, Himmerfjärden, out into the open Baltic Sea. The model is a simple implementation of the “ecosystem approach,” because the optical constituents are proxies for important components of ecosystem state. Yellow substance or colored dissolved organic matter (CDOM) is often a marker for terrestrial freshwater or decay processes in the littoral zone. Phytoplankton pigments, especially chlorophyll a, are used as a proxy for phytoplankton biomass that may be stimulated by fluvial or coastal inputs of anthropogenic nutrients. Suspended particulate matter (SPM) is placed in suspension by tidal or wind-wave stirring of shallow seabeds, and is therefore an indicator for physical forcing. It is the thesis of this article that such constituents, and the optical properties that they control, can be used to provide an ecological definition of the extent of the coastal zone. The spatial distribution of the observations was analyzed using a steady-state model that assumes diffusional transport of bio-optical variables along an axis perpendicular to the coast. According to the model, the resulting distribution along this axis can be described as a low-order polynomial (of order 1–3) when moving from a “source” associated with land to the open-sea “sink.” Order 1 implies conservative mixing, and the higher orders imply significant biological or chemical processes within the gradient. The analysis of the transect data confirmed that the trend of each optical component could be described well using a low-order polynomial. Multiple regression analysis was then used to weigh the contribution of each optical component to the spectral attenuation coefficient K d(490) along the transect. The results showed that in this Swedish Baltic case study, the inorganic fraction of the SPM may be used to distinguish between coastal and open-sea waters, as it showed a clear break between coastal and open-sea waters. Alternative models may be needed for coastal waters in which fronts interrupt the continuity of mixing.

  • 297.
    Kratzer, Susanne
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Vinterhav, Christian
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Improvement of MERIS level 2 products in Baltic Sea coastal areas by applying the Improved Contrast between Ocean and Land processor (ICOL) - data analysis and validation2010In: Oceanologia, ISSN 0078-3234, Vol. 52, no 2, p. 211-236Article in journal (Refereed)
    Abstract [en]

    In this paper we compare the following MERIS processors against sea-truthing data: the standard MERIS processor (MEGS 7.4.1), the Case 2 Regional processor (C2R) of the German Institute for Coastal Research (GKSS), and the Case 2 Water Properties processor developed at the Freie Universitat Berlin (FUB). Furthermore, the Improved Contrast between Ocean and Land processor (ICOL), a prototype processor for the correction of adjacency effects from land, was tested on all three processors, and the retrieval of level 2 data was evaluated against sea-truthing data, before and after ICOL processing. The results show that by using ICOL the retrieval of spectral reflectance in the open sea was improved for all processors. After ICOL processing, the FUB showed rather small errors in the blue, but underestimated in the red -34% Mean Normalised Bias (MNB) and 37% Root Mean Square (R,MS). For MEGS the reflectance in the red was underestimated by about -20% MNB and 23% RMS, whereas the reflectance in the other channels was well predicted, even without any ICOL processing. The C2R, underestimated the red with about -27% MNB and 29% RMS and at 412 nm it overestimated the reflectance with about 23% MNB and 29% RMS. At the outer open sea stations ICOL processing did not have a strong effect: the effect of the processor diminishes progressively up to 30 km from land. At the open sea stations the ICOL processor improved chlorophyll retrieval using MEGS from -74% to about 34% MU; and TSM retrieval from -63% to about 22% MNB. Using FUB in combination with ICOL gave even better results for both chlorophyll (25% MNB and 45% RMS) and TSM (-4% MNB and 36% EMS) in the open Baltic Sea. All three processors predicted TSM rather well, but the standard processor gave the best results (-12% MNB and 17% RMS). The C2R had a very low MNB for TSM (1%), but a rather high RMS (54%). The FUB was intermediate with -16% MNB and 31% RMS. In coastal waters, the spectral diffuse attenuation coefficient K-d (490) was well predicted using PUB or MEGS in combination with ICOL (MNB about 12% for FUB and 0.4% for MEGS). Chlorophyll was rather well predicted in the open Baltic Sea using FUB with ICOL (MNB 25%) and even without ICOL processing (MNB about 15%). ICOL-processed MEGS data also gave rather good retrieval of chlorophyll in the coastal areas (MNB of 19% and RMS of 28%). In the open Baltic Sea chlorophyll retrieval gave a MNB of 34% and RMS of 70%, which may be due to the considerable patchiness caused by cyanobacterial blooms. The results presented here indicate that with the MERIS mission, ESA and co-workers are in the process of solving some of the main issues regarding the remote sensing of coastal waters: spatial resolution; land-water adjacency effects; improved level 2 product retrieval in the Baltic Sea, i.e. the retrieval of spectral reflectance and of the water quality products TSM and chlorophyll.

  • 298.
    Kumblad, Linda
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Bradshaw, Clare
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Element composition of biota, water and sediment in the Forsmark area, Baltic Sea: Concentrations, bioconcentration factors and partitioning coefficients (Kd) of 48 elements2008Report (Other academic)
  • 299.
    Kumblad, Linda
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Söderbäck, B
    Löfgren, A
    Lindborg, T
    Wijnbladh, Erik
    Kautsky, Ulrik
    Pools and fluxes of organic matter in a boreal landscape: Implications for a safety assessment of a repository for nuclear waste2006In: Ambio, Vol. 35, no 8, p. 496-504Article in journal (Refereed)
  • 300. Kuussaari, Mikko
    et al.
    Bommarco, Riccardo
    Heikkinen, Risto K.
    Helm, Aveliina
    Krauss, Jochen
    Lindborg, Regina
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Öckinger, Erik
    Pärtel, Meelis
    Pino, Joan
    Rodà, Ferran
    Stefanescu, Constantí
    Teder, Tiit
    Zobel, Martin
    Steffan-Dewenter, Ingolf
    Extinction debt: a challenge for biodiversity conservation2009In: Trends in Ecology & Evolution, ISSN 0169-5347, E-ISSN 1872-8383, Vol. 24, no 10, p. 564-571Article in journal (Refereed)
    Abstract [en]

    Local extinction of species can occur with a substantial delay following habitat loss or degradation. Accumulating evidence suggests that such extinction debts pose a significant but often unrecognized challenge for biodiversity conservation across a wide range of taxa and ecosystems. Species with long generation times and populations near their extinction threshold are most likely to have an extinction debt. However, as long as a species that is predicted to become extinct still persists, there is time for conservation measures such as habitat restoration and landscape management. Standardized long-term monitoring, more high-quality empirical studies on different taxa and ecosystems and further development of analytical methods will help to better quantify extinction debt and protect biodiversity.

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