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  • 1.
    Aronsson, Andreas
    et al.
    Mid Sweden University, Department of Natural Sciences.
    Ekelund, Nils
    Mid Sweden University, Department of Natural Sciences.
    Biological effects of wood ash application to forest and aquatic ecosystems2004In: Journal of Environmental Quality, ISSN 0047-2425, E-ISSN 1537-2537, Vol. 33, no 5, p. 1595-1605Article, review/survey (Refereed)
    Abstract [en]

    The present review aims to summarize current knowledge in the topic of wood ash application to boreal forest and aquatic ecosystems, and the different effects derived from these actions. Much research has been conducted regarding the effects of wood ash application on forest growth. Present studies show that, generally speaking, forest growth can be increased on wood ash–ameliorated peatland rich in nitrogen. On mineral soils, however, no change or even decreased growth have been reported. The effects on ground vegetation are not very clear, as well as the effects on fungi, soil microbes, and soil‐decomposing animals. The discrepancies between different studies are for the most part explained by abiotic factors such as variation in fertility among sites, different degrees of stabilization, and wood ash dosage used, and different time scales among different studies. The lack of knowledge in the field of aquatic ecosystems and their response to ash application is an important issue for future research. The few studies conducted have mainly considered changes in water chemistry. The biotoxic effects of ash application can roughly be divided into two categories: primary and secondary. Among the primary effects is toxicity deriving from compounds in the wood ash and cadmium is probably the worst among these. The secondary effects of wood ash are generally due to its alkaline capacity and a release of ions into the soil and soil water, and finally, watercourses and lakes. Given current knowledge, we would recommend site‐ and wood ash–specific application practices, rather than broad and general guidelines for wood ash application to forests.

  • 2. Aronsson, Andreas
    et al.
    Ekelund, Nils
    Effects on growth, photosynthesis and pigments of the freshwater moss Fontinalis antipyretica Hedw. after exposure to wood ash solution2006In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 372, no 1, p. 236-246Article in journal (Refereed)
    Abstract [en]

    The application of wood ash from biofuel sources to the forest has been suggested as a source of nutrients for trees and for restoration of acidified soils and surface waters. Studies on the effects of wood ash on aquatic organisms and ecosystems are, however, few. This study investigated the effects of wood ash (0.1–10 g l− 1) on the freshwater moss Fontinalis antipyretica Hedw., which has previously been shown to be a sensitive test organism for assessing environmental pollution. After nine weeks of treatment with wood ash, a significant effect of enhanced stem growth was observed at higher concentrations (1–10 g l− 1). The concentration of wood ash was also correlated with the growth of secondary branches. Photosynthesis (oxygen evolution after 4 h of exposure to wood ash) was significantly lower in the alkaline treatments (no pH adjustment) compared to the treatments with neutral wood ash solutions (pH adjusted to 7.5). Furthermore, photosynthesis in the alkaline wood ash treatments was significantly lower compared to the control. The ratio between the optical density value before and after acidification (OD665/665a) was higher for all wood ash concentrations compared to the control. The OD665/665a values ranged from 1.52 to 1.61 and there was a difference, however not significant, between the alkaline and the neutral treatment at 10 g l− 1 wood ash. This study clearly demonstrated that wood ash may be beneficial for F. antipyretica at moderate concentrations (0.5–5 g l− 1), particularly when a sudden increase in pH is avoided.

  • 3.
    Aronsson, Andreas
    et al.
    Mid Sweden University, Department of Natural Sciences.
    Ekelund, Nils
    Mid Sweden University, Department of Natural Sciences.
    Effects on Motile Factors and Cell Growth of Euglena gracilis After Exposure to Wood Ash Solution; Assessment of Toxicity, Nutrient Availability and pH-Dependency2005In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 162, p. 353-368Article in journal (Refereed)
    Abstract [en]

    Wood ash application (WAA) to the forest has been suggested as a resource of nutrients for trees and for restoration of acidified soils and surface waters. However, studies of the effects of WAA on aquatic systems are few. This study investigated the effects of wood ash (1–25 g L−1) on the unicellular flagellate Euglena gracilis, which has been proved to be a sensitive test organism for assessing environmental change. Long-term (7 days) growth studies and short-term (direct, 24 and 48 h) studies of different motile factors, using the automatic biological test system Ecotox, were conducted. The results show no indication of biotoxic effects due to wood ash (adjusted to neutral) treatments. However, when no adjustments of pH in wood ash solutions were made, inhibitory effects on motile factors and cell growth were observed at higher concentrations of wood ash (10–25 g L−1) due to high pH (> 8). In tests with pH adjusted to neutral, enhanced motility was observed. These results indicate that high concentration of WAA could affect freshwater environments.

  • 4.
    Aronsson, Andreas
    et al.
    Mid Sweden University, Department of Natural Sciences.
    Ekelund, Nils
    Mid Sweden University, Department of Natural Sciences.
    Limnological effects on a first order stream after Wood Ash Application to a boreal forest catchment in Bispgården, Sweden.2008In: Forest Ecology and Management, ISSN 0378-1127, E-ISSN 1872-7042, Vol. 255, no 1, p. 245-253Article in journal (Refereed)
    Abstract [en]

    In Sweden, whole tree harvest is common practice, possibly leading to the depletion of mineral nutrients. Furthermore, the increased use of forestry residues for heat production has caused an increasingly growing amount of by-product consisting of wood ash. Therefore, the Swedish Forest Agency has recommended wood ash application (WAA) to replace the mineral nutrients removed by whole tree harvesting, as well as a means to mitigate the acidification of boreal forests and surface waters. In a multidisciplinary study during 2003–2006 in Bispgården (Sweden), we have investigated the limnological effects on a first order stream after WAA (conducted in 2004; 3000 kg ha−1) to a 50-ha forested catchment. In general, no significant effects on an annual basis were found for acidification parameters, such as pH, alkalinity and toxic forms of aluminum (Al). There was, however, evidence of an increased pH during the spring flood, accompanied by a simultaneous decrease in the frequency of low pH-values (<5.6). Moreover, alkalinity increased in the years 2005 and 2006 compared to that of 2003, although the increase in 2006 was not statistically different from that in 2005 or 2003. High concentrations of Al repeatedly occurred in the stream, and the WAA did not affect the frequencies of high concentrations of toxic Al forms (>50 μg l−1). The benthic diatom community did not change as a result of the wood ash treatment and the diatom-based index IPS (Indice de PulluoSensibilité) indicated no nutrient enrichment or organic pollution of the stream water. There were, however, indices of elevated concentrations of potassium (K) in the aquatic moss Fontinalis antipyretica and in leaves from Alder (Alnus incana). We conclude that wood ash treatment of a forested catchment with the dose and form of ash applied in this study did not modify the freshwater ecosystem of a first order stream.

  • 5. Aronsson, Andreas
    et al.
    Ekelund, Nils
    Respiration measurements can assess the fitness of Gammarus pulex (L.) after exposure to different contaminants; experiments with wood ash, cadmium and aluminum2005In: Archive für Hydrobiologie, ISSN 0003-9136, Vol. 164, no 4, p. 479-491Article in journal (Refereed)
    Abstract [en]

    Wood ash application has been suggested as a means to mitigate acidification of surface waters. However little is known about the effects of wood ash to freshwater organisms. A Clark-type oxygen electrode was used to investigate the effects of wood ash, cadmium and aluminum on the respiration of the freshwater amphipod Gammarus pulex (L.). Harmful effects following wood ash addition were primarily found to be explained by elevated pH. At high concentrations (> 1g/l) of wood ash the respiration of G. pulex decreased when no adjustment of pH was made, a response that was negatively correlated to the elevated pH (r = −0.43). An ion-related response was also detected in the pH-adjusted (pH 7) tests, although it was not statistically significant. Cadmium proved to be sublethal in the range of 0.2–0.4 mg/l in a 24-h exposure. Mortality was 100 % at 0.5 and 1.0 mg Cd/l. No effects were detected after exposure to Al, due to the high pH (pH 7–8) of the solutions and the subsequently low concentrations of labile monomeric Al. We demonstrate that the method described in this paper could be a useful probe for the detection of sublethal concentrations of contaminants in freshwater ecosystems.

  • 6. Beery, Thomas
    et al.
    Stålhammar, Sanna
    Jönsson, K. Ingemar
    Wamsler, Christine
    Bramryd, Torleif
    Brink, Ebba
    Ekelund, Nils
    Malmö högskola, Faculty of Education and Society (LS), Department of Nature, Environment and Society (NMS).
    Johansson, Michael
    Palo, Thomas
    Schubert, Per
    Malmö högskola, Faculty of Education and Society (LS), Department of Nature, Environment and Society (NMS).
    Perceptions of the ecosystem services concept: Opportunities and challenges in the Swedish municipal context2016In: Ecosystem Services, ISSN 2212-0416, E-ISSN 2212-0416, Vol. 17, p. 123-130Article in journal (Refereed)
    Abstract [en]

    A current focus of ecosystem services (ES) implementation is on the municipal level of government where international and national legislation and policies have to be translated into practice. Given this focus, an understanding of perceptions within municipalities of the ES concept is crucial to support the implementation process. Against this background, this paper examines the perceptions of Swedish municipal stakeholders for the ES concept. A 2013 Swedish federal mandate that states that the values of ecosystem services should be considered in relevant decision-making processes, provides a timely context. Current perceptions, preconditions and awareness are explored via interviews and analyses. The results show that the views on the ecosystem services concept and its usefulness are generally very positive. Conceptual knowledge use is perceived as important as is the recognition of monetary valuation of ES. However, clarification of the distinction between implicit and explicit use of the concept by stakeholders is needed. Finally, results indicate that a deeper understanding of monetary valuation of ecosystem services by municipal staff members is connected with a more critical view on monetary valuation. It is concluded that detailed and clear definitions and guidelines are needed in order to support the process of implementing ES in municipalities.

  • 7. Björn, Gunvor S
    et al.
    Ekelund, Nils
    Björn, Lars Olof
    Light-induced lineardichroism in photoreversibly photochromic sensor pigments - IV. Lack of chromophore rotation in  phycochrome b immobilized in vitro.1984In: Physiologia Plantarum, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 60, p. 253-256Article in journal (Refereed)
    Abstract [en]

    In photochromic pigments, immobilized on Sepharose beads to prevent reorientation of the molecules, linear absorption dichroism can be induced with plane‐polarized light. This phenomenon was used to study the relation between the carrier protein and the chromophore in the photochromic cyanobacterial pigment, phycochrome b, from Tolypothrix distorta var. symplocoides Hansgirg, strain UTEX 424 (formerly IUCC 424). It was found that the transition moment of the chromophore has the same direction with respect to the protein in the long‐wavelength and the short‐wavelength forms of phycochrome b. This contrasts to earlier results for phytochrome in higher plants, in which the transition moment was found to rotate 32° (or 180°—32°) when the long‐wavelength form was converted to the short‐wavelength form or vice versa.

  • 8.
    Björn, Lars Olof
    et al.
    Inst. för cell- och organismbiologi, Lunds universitet.
    Ekelund, Nils
    Inst. för naturvetenskap och miljö, Mittuniversitetet.
    Dinoflagellater – hopplock från livets smörgåsbord [Dinoflagellates – collections from the smorgasbord of the living world]2005In: Svensk Botanisk Tidskrift, ISSN 0039-646X, Vol. 99, p. 7-16Article in journal (Other (popular science, discussion, etc.))
    Abstract [en]

    The dinoflagellates constitute a group within the protistan supergroup Alveolata, and can be referred neither to the plant nor the animal kingdom. They swim about using two flagella and orient using various stimuli. About half of the species are capable of oxygenic photosynthesis, but most of them complement this with capture of prey. Some live entirely by capturing small organisms, others are parasites. Some species are able to emit light. The group has a long evolutionary history, and almost as many extinct species as extant ones have been described. Remarkable is the way the photosynthetically potent dinoflagellates have acquired their chloroplasts by endosymbiosis with photosynthetic organisms from many different groups. In some cases repeated endosymbiotic events have taken place.

  • 9. Björn, Lars Olof
    et al.
    Ekelund, Nils
    Inst. för naturvetenskap, Mittuniversitetet.
    Koraller och deras fotosyntetiska endosymbionter, zooxantellerna2006In: Svensk Botanisk Tidskrift, ISSN 0039-646X, Vol. 100, no 4, p. 263-270Article in journal (Other (popular science, discussion, etc.))
  • 10. Braune, W
    et al.
    Ekelund, Nils
    Institutionen för Fysiologisk Botanik, Lunds Universitet.
    Phototactic responses in Haematococcus lacustris and its modification by light intensity and the carotenoid biosynthesis inhibitor Norflurazon1990In: Archives of Microbiology, ISSN 0302-8933, E-ISSN 1432-072X, Vol. 154, p. 448-452Article in journal (Refereed)
    Abstract [en]

    At fluence rates below 45 W· m-2 cells of the flagellate stage of Haematococcus lacustris react only positively phototactically with a rather high degree of orientation (indicated by r values up to 0.66 with the Rayleigh test). The directedness of orientation decreases with decreasing irradiance. The degree of directedness of the phototactic response depends on the intensity of preirradiation: Low light intensity applied after strong light application results in a “dark reaction” (low r values), low light given after darkness stimulates a rather high degree of directedness of positive phototaxis. Weak blue light (λ=483 nm; 0.4 W · m-2) stimulates positive phototactic response, whereas comparable red light (λ=658 nm; 0.5 W · m-2) does not.

  • 11. Brink, Ebba
    et al.
    Wamsler, Christine
    Adolfsson, Maria
    Axelsson, Monika
    Beery, Thomas
    Björn, Helena
    Bramryd, Torleif
    Ekelund, Nils
    Malmö University, Faculty of Education and Society (LS), Department of Natural Science, Mathematics and Society (NMS).
    Jepshon, Therese
    Narvelo, Widar
    Jönsson, Ingemar K
    Palo, Thomas
    Stålhammar, Sanna
    Thiere, Geraldine
    Ness, Barry
    Sjeldrup, Magnus
    On the road to research municipalities: Analysing transdisciplinarity in municipal ecosystem services and adaptation planning2018In: Sustainability Science, ISSN 1862-4065, E-ISSN 1862-4057, Vol. 13, no 3, p. 765-784Article in journal (Refereed)
    Abstract [en]

    Transdisciplinary research and collaboration is widely acknowledged as a critical success factor for solution- oriented approaches that can tackle complex sustainability challenges, such as biodiversity loss, pollution, and climate-related hazards. In this context, city governments’ engagement in transdisciplinarity is generally seen as a key condition for societal transformation towards sustainability. However, empirical evidence is rare. This paper presents a self-assessment of a joint research project on ecosystem services and climate adaptation planning (ECOSIMP) undertaken by four universities and seven Swedish municipalities. We apply a set of design principles and guiding questions for transdisciplinary sustainability projects and, on this basis, identify key aspects for supporting university–municipality collaboration. We show that: (1) selecting the number and type of project stakeholders requires more explicit consideration of the purpose of societal actors’ participation; (2) concrete, interim benefits for participating practitioners and organisations need to be continuously discussed; (3) promoting the ‘inter’, i.e., interdisciplinary and inter-city learning, can support transdisciplinarity and, ultimately, urban sustainability and long-term change. In this context, we found that design principles for transdisciplinarity have the potential to (4) mitigate project shortcomings, even when transdisciplinarity is not an explicit aim, and (5) address differences and allow new voices to be heard. We propose additional guiding questions to address shortcomings and inspire reflexivity in transdisciplinary projects.

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  • 12.
    Christensen, Jonas
    et al.
    Malmö University, Faculty of Health and Society (HS), Department of Social Work (SA).
    Ekelund, Nils
    Malmö University, Faculty of Education and Society (LS), Department of Natural Science, Mathematics and Society (NMS).
    Melin, Margareta
    Malmö University, Faculty of Culture and Society (KS), School of Arts and Communication (K3).
    Widén, Pär
    Malmö University, Faculty of Education and Society (LS), Department of Culture, Languages and Media (KSM).
    The Beautiful Risk of Collaborative and Interdisciplinary Research. A Challenging Collaborative and Critical Approachtoward Sustainable Learning Processes in Academic Profession2021In: Sustainability, E-ISSN 2071-1050, Vol. 13, p. 1-20Article in journal (Refereed)
    Abstract [en]

    In this article, we aim to identify and explore possibilities and challenges of academicinterdisciplinary capacities and ethos. The objective is that this knowledge could be used both infuture interdisciplinary research projects and in educational settings. We achieve this through selfreflectivelearning processes among a group of interdisciplinary scholars from four distinctly differentsubjects. The method used is an autoethnographic and empirical self-reflective approach to datacollection, analysis and deconstruction of professional learning processes. This also serves to establishresearch methodological trustworthiness and authenticity. The results show that interdisciplinarityis undervalued by grant-giving institutions and the academic system, in general. It also entailstime-consuming and risky research practices. However, interdisciplinary and collaborative researchcreates a more innovative and stimulating learning environment and enforces new ways of thinkingand doing, in ascertaining each individual’s knowledge and competences. We argue that a long-terminterdisciplinary and collaborative research process could enhance and raise a critical thinking andcreative consciousness among scholars, contributing to a more holistic, sustainable and socially robustlearning in research and higher education. Finally, we conclude that this academic interdisciplinarycapacity and ethos could be framed and enhanced by the notion of Challenge-Based Learning.

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  • 13.
    Christersson, Cecilia E.
    et al.
    Malmö University, Faculty of Odontology (OD).
    Melin, Margareta
    Malmö University, Faculty of Culture and Society (KS), School of Arts and Communication (K3).
    Widén, Pär
    Malmö University, Faculty of Education and Society (LS), Department of Culture, Languages and Media (KSM).
    Ekelund, Nils
    Malmö University, Faculty of Education and Society (LS), Department of Natural Science, Mathematics and Society (NMS).
    Christensen, Jonas
    Malmö University, Faculty of Health and Society (HS), Department of Social Work (SA).
    Lundegren, Nina
    Malmö University, Faculty of Odontology (OD).
    Staaf, Patricia
    Malmö University, Faculty of Education and Society (LS), Centre for Teaching and Learning (CAKL).
    Challenge-Based Learning in Higher Education: A Malmö University Position Paper2022In: International Journal of Innovative Teaching and Learning in Higher Education, ISSN 2644-1624, Vol. 3, no 1, p. 1-14Article in journal (Refereed)
    Abstract [en]

    Higher education institutions (HEIs) have a pivotal role in fulfilling the social dimension of sustainability and contributing to a complex changing society. To meet these challenges, Malmö University has in interdisciplinary groups researched the role of challenge-based learning (CBL) in relation to staff, students, disciplines, and stakeholders. This position paper is based on that work. Malmö University argues that with a CBL approach, HEIs will actively contribute to the building of a sustainable learning society through collaboration in education, research, and innovation. This paper theoretically explores the CBL approach as a collaborative learning exchange within HEIs and society at large. CBL is defined through eight key elements, clustered as entities of three domains: diversity and inclusion, co-creation and collaboration, and change agents and contextual challenges. These are discussed and empirically exemplified with the purpose to support designing, planning, and accomplishing CBL in teaching and learning in HE for a global learning society.

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    Fulltext
  • 14.
    Danilov, R. A.
    et al.
    Department of Applied Science, Mid Sweden University.
    Ekelund, Nils
    Department of Applied Science, Mid Sweden University.
    Effects of increasing doses of UV-B radiation on photosynthesis and motility in Chlamydomonas reinhardtii2000In: Folia microbiologica (Prague), ISSN 0015-5632, E-ISSN 1874-9356, Vol. 45, no 1, p. 41-44Article in journal (Refereed)
    Abstract [en]

    Effects of increasing doses of UV-B radiation on photosynthetic efficiency (PE) and motility inChlamydomonas reinhardtii were investigated. The exposure time ranged from 10 to 120 min at 0.73 W/m2 UV-B radiation. A decrease in compensation points (CP) was followed by an increase in PE on extending the UV-B treatment up to 60 min. The subsequent increase in PE was accompanied by increasing CPs. Enhanced doses of UV-B radiation thus have a stimulatory effect on the PE inC. reinhardtii. No inhibitory effects could be detected. No statistically significant differences in motility could be observed due to an extremely high variation of values.

  • 15.
    Danilov, R
    et al.
    Department of Applied Science, Mid Sweden University.
    Ekelund, Nils
    Department of Applied Science, Mid Sweden University.
    Applicability of growth rate, cell shape, and motility of Euglena gracilis as physiological parameters for bioassessment at lower concentrations of toxic substances: An experimental approach2001In: Environmental Toxicology, ISSN 1520-4081, E-ISSN 1522-7278, Vol. 16, no 1, p. 78-83Article in journal (Refereed)
    Abstract [en]

    The responses of the growth rate, motility, and cell shape in the green flagellate Euglena gracilis to different concentrations of waste water substances from the pulp and paper industry were tested in a long‐term study (7 days). Samples before (uncleaned sample) and after (cleaned sample) the treatment in a cleaning system were studied. The influence of different doses of UV‐B radiation on cell shape and motility was also investigated. No statistically significant effects of increasing concentrations of the waste substances both before and after the cleaning process (except inhibition by the undiluted uncleaned effluent) on the growth rate in E. gracilis were observed. Cell shape turned out to be an unreliable physiological parameter for assessing the toxicity at lower concentrations of waste water substances. No significant patterns could be observed in the response of the cell shape to the different concentrations of the waste water substances or to UV‐B radiation. Motility has been concluded to be a more sensitive parameter than cell shape. However, no clear patterns were observed in the response of the motility to the different concentrations of the waste water substances studied. Increasing concentrations of the uncleaned sample demonstrated a defense against UV‐B radiation, due to the high absorbance in the UV‐B range, when effects on motility were examined. We conclude that contrary to the results reported in the literature earlier, cell shape and motility of E. gracilis are not universal physiological parameters for bioassessment at lower concentrations of toxic substances, including metals such as copper and zinc from the pulp and paper industry. The long‐duration tests had, in general, higher significance than those of short duration.

  • 16.
    Danilov, R
    et al.
    Department of Applied Science, Mid Sweden University.
    Ekelund, Nils
    Department of Applied Science, Mid Sweden University.
    Autumn phytoplankton assemblages in temperate lakes of different eutrophication level in the middle part of Sweden2000In: Nordic Journal of Botany, ISSN 0107-055X, E-ISSN 1756-1051, Vol. 20, no 2, p. 225-232Article in journal (Refereed)
    Abstract [en]

    Phytoplankton assemblages were studied during autumn 1998 in oligo‐, meso‐ and eutrophic lakes in central Sweden (62°54′N). Differences in phytoplankton assemblages have been detected both in space and time. In eutrophic lakes coccoid Chlorophyceae dominated quantitatively during September and October. Diatoms were the most diverse group in all types of lakes in September and in meso‐ and oligotrophic lakes in October. In November Cryptophyceae became the most abundant group in all lakes. The total richness of species decreased in the meso‐ and oligotrophic environments in November compared to September and October, whilst in the eutrophic environment it remained almost unchanged. Cluster analyses, using both presence‐absence and presence‐absence in combination with abundance matrices, showed similar results and a good resolution between the lakes of different eutrophication conditions. We conclude that the phytoplankton assemblages of the lakes studied depended on the trophic conditions and thus they can be used for resolution between different eutrophication levels.

  • 17.
    Danilov, R
    et al.
    Department of Applied Science, Mid Sweden University.
    Ekelund, Nils
    Department of Applied Science, Mid Sweden University.
    Comparative studies on the usefulness of seven ecological indices for the marine coastal monitoring close to the shore.2001In: Environmental Monitoring & Assessment, ISSN 0167-6369, E-ISSN 1573-2959, Vol. 66, p. 265-279Article in journal (Refereed)
    Abstract [en]

    The simultaneous behaviour of seven ecological indices(Hurlbert’s, Margalef’s, Menhinick’s, Shannon’s,species number, Jaccard’s and saprobic index) wasstudied based on phytoplankton data close to the shoreon the East coast of Sweden during the summer 1998.The sampling stations had a similar eutrophicationlevel and were located in bays. Standard phytoplanktondatabases were used in calculating the indices, whichwere later compared using cluster analysis.Hurlbert’s, Margalef’s, Menhinick’s, Shannon’s andspecies number indices, as measure of communitydiversity, produced similar trends which oftendiffered from those based on Jaccard’s index ofsimilarity. However, the simultaneous use of theseindices was found meaningful as a possible part of themonitoring close to the shore. The application of asaprobic index lead to erroneous conclusions in thestudied case.

  • 18.
    Danilov, R
    et al.
    Department of Natural and Environmental Sciences, Mid Sweden University.
    Ekelund, Nils
    Department of Natural and Environmental Sciences, Mid Sweden University.
    Comparison of usefulness of three types of artificial substrata (glass, wood and plastic) when studying settlement patterns of periphyton in lakes of different trophic status2001In: Journal of Microbiological Methods, ISSN 0167-7012, E-ISSN 1872-8359, Vol. 45, p. 167-170Article in journal (Refereed)
  • 19.
    Danilov, R
    et al.
    Department of Natural Sciences, Mid Sweden University.
    Ekelund, Nils
    Department of Natural Sciences, Mid Sweden University.
    Effects of copper on growth rate, cell shape, motility and photosynthesis in the green flagellate Euglena gracilis in a long-term experiment2000In: Biologia, ISSN 0006-3088, E-ISSN 1336-9563, Vol. 55, no 4, p. 413-418Article in journal (Refereed)
    Abstract [en]

    The green flagellate Euglena gracilis was treated for seven days with concentrations of copper ranging from 0.02 mg L-1 to 2.0 mg L-1. No inhibiting effects were detected in any physiological parameters measured. In general, it seems that enhanced copper concentrations stimulated photosynthetic efficiency (PE) of E. gracilis. Concentrations of copper reported to be critical for the other algae studied (from 0.10 mg L-1 to 0.14 mg L-1) did not show any severe negative effects on E. gracilis. An unusual trend was observed where an increase in PE was followed by an increase in light irradiance necessary to achieve light compensation point. High capacity of E. gracilis to adapt to copper stress is being discussed as a possible explanation for the trends detected.

  • 20.
    Danilov, R
    et al.
    Department of Natural and Environmental Sciences, Mid Sweden University.
    Ekelund, Nils
    Department of Natural and Environmental Sciences, Mid Sweden University.
    Effects of Cu2+, Ni2+, Pb2+, Zn2+ and pentachlorophenol on photosynthesis and motility in Chlamydomonas reinhardtii in short-term exposure experiments2001In: BMC Ecology, E-ISSN 1472-6785, Vol. 1, no 1, article id 1Article in journal (Refereed)
    Abstract [en]

    Heavy metals, especially copper, nickel, lead and zinc, have adverse effects on terrestrial and in aquatic environments. However, their impact can vary depending on the nature of organisms. Taking into account the ability of heavy metals to accumulate in sediments, extended knowledge of their effects on aquatic biota is needed. In this context the use of model organisms (often unicellular), which allows for rapid assessment of pollutants in freshwater, can be of advantage. Pentachlorophenol has been extensively used for decades as a bleaching agent by pulp- and paper industry. Pentachlorophenol tends to accumulate in the nature. We aim to determine if photosynthesis and motility can be used as sensitive physiological parameters in toxicological studies of Chlamydomonas reinhardtii, a motile green unicellular alga. It is discussed if photosynthesis and motility can be used as sensitive physiological parameters in toxicological studies.

  • 21.
    Danilov, R
    et al.
    Department of Applied Science, Mid Sweden University.
    Ekelund, Nils
    Department of Applied Science, Mid Sweden University.
    Effects of different levels of UV-B radiation on marine epilithic communities: a short-term microcosm study.2000In: Scienta Marina, Vol. 64, no 4, p. 363-368Article in journal (Refereed)
    Abstract [en]

    Epilithic communities from brackish coastal water of the east coast of Sweden were studied in order to reveal their responses to different levels of UV-B radiation. The experiment was conducted for seven days in an indoor microcosm system. The epilithic communities were exposed daily to different doses of UV-B radiation: 1, 3, 5 and 7 hours, respectively. The intensity of the UV-B radiation used was similar to that in natural environments. After seven days clear shifts both in species composition and community structure were observed. All species of diatoms showed negative correlation with enhanced levels of UV-B. On the other hand, abundance of cyanobacteria was positively correlated with enhanced levels of UV-B (Calothrix aeruginea, R=0.49;Oscillatoria amphibia, R=0.93; Pseudanabaena mucicola, R=0.26). Communities dominated by diatoms and green algae at the initial stage of the experiment did show a drastic decrease in diatom abundance under UV-B stress and finally became dominated by cyanobacteria. Among green algae the abundance of Cladophora sericea correlated positively (R=0.33) with enhanced exposure to UV-B, while Monoraphidium-species exhibited negative correlation to UV-B. Otherwise, no significant correlation between other green algae species identified and UV-B stress could be detected. We conclude that UV-B radiation, even at lower levels, is capable to induce severe changes to marine epilithic communities. The trends revealed in the present study predict a shift from communities dominated by diatoms and green algae to those dominated by cyanobacteria.

  • 22.
    Danilov, R
    et al.
    Department of Natural and Environmental Sciences, Mid Sweden University.
    Ekelund, Nils
    Department of Natural and Environmental Sciences, Mid Sweden University.
    Effects of pH on the growth rate, motility and photosynthesis in Euglena gracilis2001In: Folia microbiologica (Prague), ISSN 0015-5632, E-ISSN 1874-9356, Vol. 46, no 6, p. 549-554Article in journal (Refereed)
    Abstract [en]

    The influence of pH 3–10 on the growth, motility and photosynthesis inEuglena gracilis was demonstrated during a 7-d cultivation. The cells did not survive at pH<4 and >8, highest growth rate being detected at pH 7. Motility followed a similar patterns as growth rate. Photosynthetic response curves were shown to be of the same type over the whole pH range. High respiration was characteristic for cells grown at pH 5 and 6, the lowest one at 7. At high and also at low pH more active respiration was found which can be considered as a protective response on proton stress. Respiration was not completely inhibited with potassium cyanide. Photosynthesis was the most effective at pH 6; lower and higher pH decreased photosynthetic efficiency. pH affected more the growth rate than the photosynthesis.

  • 23.
    Danilov, R
    et al.
    Department of Natural and Environmental Sciences, Mid Sweden University.
    Ekelund, Nils
    Department of Natural and Environmental Sciences, Mid Sweden University.
    Effects of short-term and long-term aluminium stress on photosynthesis, respiration and reproductive capacity in a unicellular green flagellate (Euglena gracilis)2002In: Acta hydrochim. Hydrobiol, Vol. 30, no 4, p. 190-196Article in journal (Refereed)
    Abstract [en]

    Effects of short‐term (1 h exposure) and long‐term (7 d exposure) aluminium stress on photosynthesis and reproductive capacity have been studied in Euglena gracilis strain Z. Following concentrations of Altot (added as AlCl3) were tested: 0.5 mg L‐1, 1.0 mg L‐1, 1.5 mg L‐1, 2.5 mg L‐1, 5.0 mg L‐1, 7.5 mg L‐1, 10.0 mg L‐1, and 15.0 mg L‐1 Al, respectively. Growth rates at different aluminium concentrations did not show significant differences, except at 15.0 mg L‐1Al. Initial respiration was higher in long‐term than in the short‐term experiments. It is supposed that an energy‐dependent mechanism of excretion of aluminium ions has been active in the stressed cells. Consequently, the cells of E. gracilis after long‐term exposure to aluminium are believed to be more acclimatised to the aluminium stress. Photosynthetic efficiency (PE) has been negatively affected by aluminium in all experiments performed. Differences between control algae and those treated with aluminium were significant in all cases. PE in long‐term experiments was in general significantly higher at all concentrations of aluminium studied, compared to the short‐term experiments. The aluminium concentrations tested led only to a general decrease in PE while the level of decrease was not especially concentration‐dependent. In general, aluminium tolerance of E. gracilis can be estimated as low, especially by short‐term exposure. However, good acclimatisation capacity of this green flagellate to aluminium doses by long‐term exposure can be supposed.

  • 24. Danilov, R
    et al.
    Ekelund, Nils
    Mitthögskolan.
    Effects of solar radiation, humic substances and nutrients on phytoplankton biomass in Lake Solumsjö, Sweden.2001In: Hydrobiologia, ISSN 0018-8158, Vol. 444, p. 203-212Article in journal (Refereed)
  • 25.
    Danilov, R
    et al.
    Department of Applied Science, Mid Sweden University.
    Ekelund, Nils
    Department of Applied Science, Mid Sweden University.
    Influence of chlorophyll concentrations on the reliability of measurements with an oxygen electrode when studying photosynthetic efficiency in bioassays using microalgae2000In: Journal of Applied Phycology, ISSN 0921-8971, E-ISSN 1573-5176, Vol. 12, no 1, p. 63-67Article in journal (Refereed)
    Abstract [en]

    Euglena gracilis and Chlamydomonas reinhardtii were used as model organisms to establish the best conditions for studying photosynthetic efficiency using the Light Pipette – experimental system, which enables sensitive detection of changes in oxygen evolution/consumption and an easy collection and digitalisation of data. Chlorophyll concentrations of 0.005, 0.025, 0.050 and 0.075 mgmL-1 were investigated using different light regimes. Cultures of E. gracilis at the same chlorophyll concentration absorbed more light(measured at 580 μmol m-2 s-1) than those of C. reinhardtii. Cell density had a considerable effect on the reliability of measurements. Chlorophyll concentrations between 0.025 mgChl ml-1 and 0.050 mgChlml-1 can be recommended when applying the Light Pipette system in bioassays using microalgae.

  • 26.
    Danilov, R
    et al.
    Department of Applied Science, Mid Sweden University.
    Ekelund, Nils
    Department of Applied Science, Mid Sweden University.
    Influence of waste water from the paper industry and UV-B radiation on the photosynthetic efficiency of Euglena gracilis1999In: Journal of Applied Phycology, ISSN 0921-8971, E-ISSN 1573-5176, Vol. 11, p. 157-163Article in journal (Refereed)
    Abstract [en]

    The green flagellate Euglena gracilis has been used as a model organism to elucidate the possible large-scale and short-term effects of waste substances from the pulp and paper industry on photosynthetic efficiency (PE). Different concentrations of waste substances before and after treatment in a cleaning system were studied. The uncleaned sample at concentrations up to 1:10 and the cleaned sample at concentrations up to 1:5 showed stimulating effects on the PE after 7 days of incubation compared to the control. The effects of waste substances on the PE of E. gracilis were also studied in combination with short-term studies (20 and 40 min) of ultraviolet-B radiation (UV-B, 280–320 nm). It was shown that increasing concentrations of the uncleaned sample had continuously stimulating effects on the PE and worked protectively against UV-B radiation. The cleaned sample exhibited no effects, or negative effects, on the PE of E. gracilis together with UV-B radiation compared to the experiments with only UV-B radiation. At the concentration 1:1 of the cleaned sample an increase in the PE was detected due to the high concentration of the coloured substances and a decrease in the UV-B penetration. PE revealed itself to be highly sensitive for detecting toxic effects on E. gracilis and is thus very promising for use in regular toxicity tests of waste water from pulp and paper industry.

  • 27.
    Danilov, R
    et al.
    Mid Sweden University, Department of Natural Sciences,.
    Ekelund, Nils
    Mid Sweden University, Department of Natural Sciences,.
    Phytoplankton communities at different depths in two eutrophic and two oligotrophic temperate lakes at higher latitude during the period of ice cover2001In: Acta Protozoologica, ISSN 0065-1583, E-ISSN 1689-0027, Vol. 40, p. 109-201Article in journal (Refereed)
    Abstract [en]

    Phytoplankton communities at different depths and at different locations within each lake were studied during the period of ice cover (from January to March) in two eutrophic and two oligotrophic lakes in North-Eastern Sweden. Cryptophyceae, Dinophyceae and Euglenophyceae were dominant during the whole period of investigation in eutrophic environments. Bacillariophyceae, Chlorophyceae, Chrysophyceae and Cyanophyceae were only occasionally found both in eutrophic and oligotrophic lakes. Both in eutrophic and oligotrophic lakes diversity as well as abundance of phytoplankton were considerably higher immediately under ice than near the bottom. No differences in horizontal distribution of phytoplankton assemblages were detected within each lake. However, vertical differences were more profound. It is speculated that both light availability and increased ion concentration under the ice cover can be viewed as main factors determining phytoplankton communities.

  • 28.
    Danilov, R
    et al.
    Department of Applied Science, Mid Sweden University.
    Ekelund, Nils
    Department of Applied Science, Mid Sweden University.
    Responses of photosynthetic efficiency, cell shape and motility in Euglena gracilis (Euglenophyceae) to short-term exposure to heavy metals and pentachlorophenol2001In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 132, p. 61-73Article in journal (Refereed)
    Abstract [en]

    Euglena gracilis was exposed for 24 hr to concentrationsof copper, nickel, lead and zinc ranging from 0.1 to 2.0 mg L-1 and to pentachlorophenol ranging from 0.1 to 10.0 mg L-1. Photosynthetic efficiency (PE) was inhibited by increasing concentrations of the heavy metals. Nickel was foundto be the least toxic of the metals to E. gracilis, whilethe other three metals exhibited similar levels of toxicity. Treatment with pentachlorophenol caused unusual responses of the photosynthetic apparatus probably due to the especially high toxicity of this substance. Both cell shape and motility turned out to be insensitive physiological parameters for the toxicity testing of the substances studied.

  • 29.
    Danilov, R
    et al.
    Department of Applied Science, Mid Sweden University.
    Ekelund, Nils
    Department of Applied Science, Mid Sweden University.
    The efficiency of seven diversity and one similarity indices based on phytoplankton data for assessing the level of eutrophication in lakes in central Sweden.1999In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 234, p. 15-23Article in journal (Refereed)
    Abstract [en]

    Seven diversity and one similarity indices calculated on the basis of phytoplankton data were studied for their usefulness for eutrophication studies in lakes in central Sweden. The lakes of different eutrophication levels (eutrophic, mesotrophic and eutrophic) were investigated monthly during autumn 1998. All of the diversity indices calculated (Hurlbert’s, Margalef’s, Menhinick’s, Shannon’s, Simpson’s, McNaughton’s and Species Number) failed to distinguish between different levels of eutrophication. However, the use of similarity index based on presence–absence matrices of phytoplankton species proved its high efficiency for eutrophication studies in the lakes in central Sweden. The consideration of abundance, additionally to presence–absence data, was concluded not to be as efficient as only presence–absence matrices. We recommend the use of similarity index based on presence–absence matrices of phytoplankton species as a good tool for the assessment of the level of eutrophication in the lakes studied.

  • 30.
    Danilov, R
    et al.
    Department of Applied Science, Mid Sweden University.
    Ekelund, Nils
    Department of Applied Science, Mid Sweden University.
    The use of epiphyton and epilithon data as a base for calculating ecological indices in monitoring of eutrophication in lakes in central Sweden2000In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 248, p. 63-70Article in journal (Refereed)
    Abstract [en]

    Eutrophication was monitored with the aid of one similarity and seven diversity indices in the lakes of different trophic levels (eutrophic, mesotrophic and oligotrophic) in central Sweden. The ecological indices were applied separately to epiphyton and epilithon communities. Epiphyton turned out to be inappropriate for assessing eutrophication in the lakes studied. On the other hand, Hurlbert's, Simpson's and the similarity indices turned out to be promising environmental tools when applied to the data of epilithon.

  • 31.
    Danilov, R
    et al.
    Department of Applied Science, Mid Sweden University.
    Ekelund, Nils
    Department of Applied Science, Mid Sweden University.
    Using the green flagellate Euglena gracilis Klebs as physiological dosimeter: is a long-term bioassay more significant than a short-term one?2001In: Turkish Journal of Botany, ISSN 1300-008X, E-ISSN 1303-6106, Vol. 25, p. 43-44Article in journal (Refereed)
    Abstract [en]

    The use of short-term tests with E. gracilis Klebs in order to assess toxicity cannot be viewed as absolutely preferable. At least in the case with wastewater from the pulp and paper industry, 7 day-tests could lead to more explanatory and significant results.

  • 32.
    Danilov, Roman
    et al.
    Department of Applied Science, Mid Sweden University..
    Ekelund, Nils
    Department of Applied Science, Mid Sweden University..
    Summer phytoplankton dynamics close to the shore in three brackish water bays on the East coast of Sweden (Gulf of Bothnia)2000In: Thaiszia - Journal of Botany, ISSN 1210-0420, Vol. 9, p. 131-142Article in journal (Refereed)
    Abstract [en]

    Three brackish water bays between Härnösand and Sundsvall on the East coast of Sweden (Gulf of Bothnia) were investigated between June and August 1998 in order to reveal summer phytoplankton dynamics close to the coast. All samples were collected at depth of 0,5 m. The results obtained show patterns in phytoplankton dynamics. In the spring Bacillariophyceae dominated, followed by an increase in Dinophyceae and small flagellates of Prasinophyceae and Cryptophyceae. Chlorophyceae were represented during the whole period of investigation especially with species of Monoraphidium, which often dominated or subdominated. In total 84 phytoplankton species were identified. Cluster analyses based on similarities in species’ diversity and their abundance made it easy to distinguish between the bays close to Härnösand and the Bay of Sundsvall. However, no clear differences were found between the sampling stations within the Bay of Sundsvall.

  • 33.
    Ekelund, Nils
    Malmö högskola, Faculty of Education and Society (LS), Department of Nature, Environment and Society (NMS).
    Earlier timing of ice breakup in lakes in northern Sweden as a response of a warmer climate2013Conference paper (Other academic)
  • 34.
    Ekelund, Nils
    Department of Plant Physiology, Lund University.
    Effects of calcium channel blockers and DCMU on motility and the photophobic response of Gyrodinium dorsum1989In: Archives of Microbiology, ISSN 0302-8933, E-ISSN 1432-072X, Vol. 151, p. 187-190Article in journal (Refereed)
    Abstract [en]

    The effects of the calcium channel blockers, verapamil, diltiazem and lanthanum ions and the Ca2+ dependency on motility as well as the photophobic response (stop-response) of Gyrodinium dorsum were studied. At Ca2+ concentrations below 10-3 M, motility was inhibited. La3+ inhibits the stop-response, in contrast to verapamil and diltiazem. The only calcium channel blocker that increased the amount of non-motile cells was verapamil. The results indicate that motility are Ca2+ dependent and that the stop-responses of G. dorsum could be affected by extracellular Ca2+. Effects of the photosythesis inhibitor (DCMU) on the stop-response was also determined. With background light of different wavelength (614, 658 and 686 nm) the stop-response increased. DCMU inhibited this effect of background light. Negative results with the monoclonal antibody Pea-25 directed to phytochrome and the results with DCMU, indicate that the stop-response of G. dorsum is coupled to photosynthesis rather than to a phytochrome-like pigment. Oxygen evolution, but not cell movement, was completely inhibited by 10-6 M DCMU.

  • 35.
    Ekelund, Nils
    Department of Natural Sciences, Mid Sweden University.
    Effects of protein synthesis inhibitors on photoinhibition by UV–B (280-320 nm) radiation in the flagellate Euglena gracilis1996In: Scienta Marina, Vol. 60, no 1, p. 95-100Article in journal (Refereed)
    Abstract [en]

    Irradiation of the flagellate Euglena gracilis by UV-B radiation resulted in inhibition of photosynthesis and motility. After 2 h of UV-B radiation (1.2 W m super(-2)) the rates of photosynthesis did not completely recover until after 24 h in visible light. After 24 h in darkness the rate of photosynthesis was lower but the recovery time in darkness after UV-B radiation was about the same as in the visible light. In the presence of lincomycin, inhibitor of chloroplast protein synthesis, therecovery of photoinhibition was totally blocked for up to 16 h recovery in visible light. However, after 24 h recovery in visible light together with lincomycin, photosynthesis was partially recovered but recovery in darkness together with lincomycindid not give any reparation at all of photosynthesis. The inhibition of motility had a slower recovery phase and had not fully recovered even after 72 h in visible light.

  • 36.
    Ekelund, Nils
    Department of Plant Physiology, Lund University.
    Effects of UV-B radiation on growth and motility of four phytoplankton species1990In: Physiologia Plantarum, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 78, p. 590-594Article in journal (Refereed)
    Abstract [en]

    A depletion of the stratospheric ozone layer would result in an increased UV‐B radiation, which could have harmful effects on marine organisms. The aim of this study was to determine the effects of an enhanced UV‐B radiation (280–320 nin) on the motility and growth in four Swedish phytoplanklon species. The different plankton species were exposed to different doses of UV‐B radiation during growth. The growth of the motile dinoflagellates, Gyronidium aureolum Hulburt (Ba 6), and Prorocentrum minimum (Pav.) P. Schiller (Ba 12), was more sensitive to UV‐B radiation than the non‐motile diatoms Dityhim brightwellii (P. West) Grun (Ba 15) and Phaeodactylum tricornutum Bohlin (Ba 16). One week of UV‐B radiation 2 h daily (159 J m−2 day−1), had a dramatic effect on the growth of the dinoflagellates, while the diatoms were nearly unaffected. On the other hand, when given higher intensity of UV‐B radiation (312, 468 and 624 J m−2 day−1) during the initial phase of growth, also the growth of the diatom, D. brightwellii, was inhibited. Not only the growth but also the swimming speed of the dinoflagellates C. aureolum and P. minimum were affected by UV‐B radiation. The speed decreased rapidly after 1–2 h of UV‐B radiation (312 J m−2 day−1), and after longer irradiation times the dinoflagellates lost their motility. G. aureolum exposed to UV‐B radiation, regained normal speed after two weeks of visible light.

  • 37.
    Ekelund, Nils
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Effekter av ozon- och klimatförändringar på växter och djur2008In: Fauna och flora : populär tidskrift för biologi, ISSN 0014-8903, Vol. 103, no 2, p. 10-16Article in journal (Other (popular science, discussion, etc.))
  • 38. Ekelund, Nils
    Forøget ultraviolet stråling og dens betydning for havmiljøet1992In: Naturens Verden, Vol. 2, p. 57-63Article in journal (Other (popular science, discussion, etc.))
  • 39.
    Ekelund, Nils
    Malmö högskola, Faculty of Education and Society (LS), Department of Nature, Environment and Society (NMS).
    Hur påverkar klimatförändringar sjöar och hav? = The potential effects of global climate change on oceans and lakes2012In: Vatten, ISSN 0042-2886, Vol. 68, p. 155-160Article in journal (Other academic)
    Abstract [en]

    Global increases in atmospheric CO2 and temperature are associated with an increase in the temperature of freshwater lakes and marine ecosystems. The ice breakup in lakes occur earlier which gives an opportunity for phytoplankton to grow early in the season. Another effect is a prolonged period of stratification in the lakes. Warming also may cause a shift of species in phytoplankton community. Climate models indicate that bluegreen algae will increase in relative abundance under the predicted future climate. The effects of climate change on marine ecosystems are related to shifts in water temperature, circulation, stratification, nutrient input and pH. An increase in temperature will create a rising sea level, decreasing sea-ice extent in Antarctica and Arctic and a altered patterns of ocean circulation and freshwater input. A greater light penetration into the water column caused by a reduction in sea ice may increase open-water phytoplankton primary production, although nutrient limitation could reduce the level of increase in primary production. In tropical waters are coral reefs very vulnerable to minor increases in temperature. A rising atmospheric CO2 and a resulting increased oceanic CO2 uptake will also reduce the sea-surface pH. A drop in pH makes it more difficult for corals to secrete and maintain their skeletons.

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  • 40.
    Ekelund, Nils
    Lund Univ., Section of Plant Physiology.
    Influence of UV-B radiation on light-response curves, absorption spectra and motility of four phytoplankton species1994In: Physiologia Plantarum, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 91, p. 696-702Article in journal (Refereed)
    Abstract [en]

    Several unicellular algae were exposed to artificial UV‐B (280–320 nm) radiation after adaptation to high (43 W m−2) and low (19 W m−2) visible light. UV‐B radiation had different effects on rates of photosynthesis, motility and absorption spectra for these species. Photosynthesis of Euglena gracilis and the diatom Phaeodactylum tricomution was more sensitive to UV‐B inhibition than that of the dinoflagellates Heterocapsa triquetra and Prorocentrum minimum. Not only UV‐B radiation but also high visible light had a photoinhibitory effect on photosynthesis in all four organisms. The effect on photosynthesis was observed both on the quantum yield and on the light saturation rate of photosynthesis. The dinoflagellates, in contrast to E. gracilis and P. tricorntum, absorbed strongly in the UV region (334 nm) and their absorption peaks increased after growth under high visible light or with or without UV‐B radiation for one week. The swimming speed of H. triquetra decreased more after low visible light and UV‐B radiation compared to high visible light and UV‐B radiation. The negative effects of UV‐B radiation on P. minimum and E. gracilis were most pronounced after high visible light.

  • 41.
    Ekelund, Nils
    Department of Applied Science, Mid Sweden University.
    Interactions between photosynthesis and ‘light-enhanced dark respiration’ (LEDR) in the flagellate Euglena gracilis after irradiation with ultraviolet radiation2000In: Journal of Photochemistry and Photobiology. B: Biology, ISSN 1011-1344, E-ISSN 1873-2682, Vol. 55, no 1, p. 63-69Article in journal (Refereed)
    Abstract [en]

    The effects of ultraviolet radiation (UV-A, 315–400 nm plus UV-B, 280–315 nm) on photosynthesis and ‘light-enhanced dark respiration’ (LEDR) in Euglena gracilis have been investigated by using light pulses (80 s) with increasing photon fluence rates of 59, 163, 600, 1180, 2080 and 3340 μmol m−2 s−1 and dark periods between the light pulses. LEDR is estimated as the maximum rate of oxygen consumption after a period of light minus the rate of oxygen consumption 30 s after the maximum rate. Without any exposure to UV radiation, the photosynthetic rate and LEDR increase with increasing photon fluence rate. After 20 and 40 min exposures to UV radiation, the photosynthetic rate and LEDR as functions of photon fluence rate are reduced. After a 20 min UV treatment respiration is greater than photosynthesis after the first light pulse of 59 μmol m−2 s−1 radiation, and especially at higher photon fluence rates photosynthesis is lower than the control values. The inhibitory effects of UV radiation on photosynthetic rate and LEDR are greater after a 40 min UV exposure than after a 20 min exposure. Only at 600 μmol m−2 s−1 is the rate of oxygen evolution greater than that of oxygen consumption after a 40 min UV treatment. Both photosynthetic rate and LEDR are inhibited by the photosynthetic inhibitor DCMU (10−5 M) in a similar way, which indicates close regulatory interactions between photosynthesis and LEDR. Potassium cyanide (KCN) inhibits dark respiration more than it inhibits LEDR. Dark respiration is not affected to the same degree by UV radiation as are photosynthesis and LEDR.

  • 42.
    Ekelund, Nils
    Inst f fysiologisk botanik, Lunds universitet.
    Ljusrörelser hos mikroorganismer1988In: Svensk Botanisk Tidskrift, ISSN 0039-646X, Vol. 82, p. 333-336Article, review/survey (Refereed)
  • 43.
    Ekelund, Nils
    Malmö University, Faculty of Education and Society (LS), Department of Natural Science, Mathematics and Society (NMS).
    Spridning av urbana miljöer och dess effekter på ekosystemtjänster2020In: Landskapets betydelse: ELC och EST som inspiration för ett hållbart landskap / [ed] Karen Lagercrantz, Malmö: Opto HB , 2020, , p. 76p. 62-66Chapter in book (Other (popular science, discussion, etc.))
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  • 44.
    Ekelund, Nils
    Department of Plant Physiology, University of Lund.
    Studies on the effects of UV-B radiation on phytoplankton of Sub-Antarctic lakes and ponds1992In: Polar Biology, ISSN 0722-4060, E-ISSN 1432-2056, Vol. 12, p. 533-537Article in journal (Refereed)
    Abstract [en]

    Experiments were performed to determine the effects of UV-B (ultraviolet, 280–320 nm) radiation on motility and growth of phytoplankton from lakes and ponds in South Georgia. After 4 h of solar radiation and 4h artificial radiation (UV-BBE 11.6 kJ m-2 day-1, UV-B lamps) the swimming velocity of Cryptomonas sp. decreased. The growth rate of Botryococcus, Lyngbya sp. and Stauraslrum sp. did not show any significant variations between the different light conditions. The UV-B component was reduced by filtering solar radiation through glass bottles und cellulose acetate. Cloudy days had only 30% of the radiation of clear days in both the PAR (photosynthetic active radiation) and UV-B regions. The ponds contained large amounts of humic substances, which are responsible for the absorbance in the UV region.

  • 45.
    Ekelund, Nils
    Department of Plant Physiology, Lund University.
    The effect of UV-B radiation and humic substances on growth and motility of the flagellate, Euglena gracilis1993In: Journal of Plankton Research, ISSN 0142-7873, E-ISSN 1464-3774, Vol. 15, p. 715-722Article in journal (Refereed)
    Abstract [en]

    The effects of ultraviolet-B radiation (UV-B, 250–315 nm) were determined on Euglena gracilis with respect to speed, phototactic orientation, specific growth rate, and in the presence of humic substances. Humic substances had a protective effect when studying the speed and specific growth rate. However, the degree of phototactic orientation decreased in UV-B radiation both with and without humic substances. The inhibition of O2 evolution and speed was most pronounced when using cutoff filters WG280 and WG295. The photosynthetic inhibitor DCMU (10−6 M) did not have any effect on the speed, but the 02 evolution decreased to zero. The effect of different wavelengths in the UV-B region on the speed of E.gracilis showed the maximum sensitivity at 280 and 290 nm.

  • 46.
    Ekelund, Nils
    Department of Plant Physiology, Lund University.
    The effects of UV-B radiation on dinoflagellates1991In: Journal of plant physiology (Print), ISSN 0176-1617, E-ISSN 1618-1328, Vol. 138, p. 274-278Article in journal (Refereed)
    Abstract [en]

    Ultraviolet radiation, UV-B (280-320 nm), has harmful effects on marine phytoplankton. The presentexperiments were done to determine the effects of UV-B radiation on motility and growth of four marine motile dinoflagellates, Gyrodinium aureolum, Prorocentrum minimum, Heterocapsa triquetra and Scrippsiella trochoidea. The specific growth rate of the dinoflagellates showed an inhibition after 1 hour UV-B (1.5 kj m(su-2}day-1) daily during 1 week. The motility of H. triquetra showed a pronounced inhibition after 12 kJ m-2day-1, the motility of S. trochoidea did not show the same sensitivity to UV-B radiation. The photosynthetic inhibitor DCMU (10-5M) inhibited the motility of S. trochoidea but not the motility of H. triquetra. Action spectra (UV-B, 280-320 nm) for inhibition of motility of G. aureolum showed the maximum sensitivity at 280 and 290 nm.

  • 47.
    ekelund, nils
    Malmö University, Faculty of Education and Society (LS), Department of Natural Science, Mathematics and Society (NMS).
    Urbaniseringens effekter på våra ekosystem och landskap2020In: Tidskriften Landskap, ISSN 2001-1903, no 2, p. 40-41Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    För närvarande lever vi i en tid med stora samhällsutmaningar och som ytterligare aktualiserades hösten 2018 när International Plant Protection Convention, IPPC publicerade en rapport gällande de klimatförändringar som pågår (IPCC, 2018).

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  • 48.
    Ekelund, Nils
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Växter som kan simma2012In: Havsutsikt., ISSN 1104-0513, Vol. 1, p. 8-9Article in journal (Other (popular science, discussion, etc.))
  • 49.
    Ekelund, Nils
    Department of Natural Sciences, Mid Sweden University.
    Växters fotosyntes vid förändrade miljöförhållanden.2001In: Fauna och flora : populär tidskrift för biologi, ISSN 0014-8903, Vol. 96, no 1, p. 15-24Article in journal (Other (popular science, discussion, etc.))
  • 50.
    Ekelund, Nils
    Inst f fysiologisk botanik, Lunds universitet.
    Öresund1989Report (Other (popular science, discussion, etc.))
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