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  • 101.
    Sörenson, Eva
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Bertos-Fortis, Mireia
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Farnelid, Hanna
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Kremp, Anke
    Finnish Environment Institute, Finland;Leibniz Institute for Baltic Sea Research Warnemunde, Germany.
    Kruget, Karen
    Max Planck Institute for Marine Microbiology, Germany.
    Lindehoff, Elin
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Finnish Environment Institute, Finland.
    Legrand, Catherine
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Consistency in microbiomes in cultures of Alexandrium species isolated from brackish and marine waters2019In: Environmental Microbiology Reports, ISSN 1758-2229, E-ISSN 1758-2229, Vol. 11, no 3, p. 425-433Article in journal (Refereed)
    Abstract [en]

    Phytoplankton and bacteria interactions have a significant role in aquatic ecosystem functioning. Associations can range from mutualistic to parasitic, shaping biogeochemical cycles and having a direct influence on phytoplankton growth. How variations in phenotype and sampling location, affect the phytoplankton microbiome is largely unknown. A high‐resolution characterization of the bacterial community in cultures of the dinoflagellate Alexandrium was performed on strains isolated from different geographical locations and at varying anthropogenic impact levels. Microbiomes of Baltic Sea Alexandrium ostenfeldii isolates were dominated by Betaproteobacteria and were consistent over phenotypic and genotypic Alexandrium strain variation, resulting in identification of an A. ostenfeldii core microbiome. Comparisons with in situ bacterial communities showed that taxa found in this A. ostenfeldii core were specifically associated to dinoflagellate dynamics in the Baltic Sea. Microbiomes of Alexandrium tamarense and minutum, isolated from the Mediterranean Sea, differed from those of A. ostenfeldii in bacterial diversity and composition but displayed high consistency, and a core set of bacterial taxa was identified. This indicates that Alexandrium isolates with diverse phenotypes host predictable, species‐specific, core microbiomes reflecting the abiotic conditions from which they were isolated. These findings enable in‐depth studies of potential interactions occurring between Alexandrium and specific bacterial taxa.

  • 102.
    Theulen, Jan
    et al.
    r Global Environmental Sustainability, HeidelbergCement Group, Germany .
    Legrand, Catherine
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Harvesting CO2 from cement kiln flue gas using micro-algae: valuable biomass production in Sweden2016Conference paper (Other academic)
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  • 103. Thorén, AK
    et al.
    Legrand, Catherine
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Herrmann, Jan
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Transport and transformation of de-icing urea from airport runways in a constructed wetland system2003In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 48, no 5, p. 283-290Article in journal (Refereed)
    Abstract [en]

    Urea, NH2-CO-NH2, is used as a de-icing agent at Kalmar Airport, southeast Sweden. During 1998-2001, urea contributed on average 30% of the yearly nitrogen (N) transport of 41,000 kg via Tornebybacken stream to the coastal zone of the Baltic Sea. In order to reduce stream transport of N from airport, agricultural and other diffuse sources, a wetland was constructed in 1996. Annual wetland retention of total-N varied in the range of 2,500-8,1100 kg (6-36% of influent) during 1998-2001, according to mass balances calculated from monthly sampling. During airport de-icing, January-March 2001, 660 kg urea-N out of 2,600 kg applied urea-N reached the wetland according to daily sampling. This indicated that 75% of the urea was transformed before entering the wetland. Urea was found to be only a minor part (8%) of total-N in the wetland influent. Calculations of cumulative urea-N loads at the wetland inlet and outlet respectively, showed a significant urea. transformation during February 2001 with approximately 40% of the incoming urea-N being transformed in the wetland system. These results show that significant amounts of urea can be transformed in a wetland system at air temperatures around 0degreesC. 

  • 104. Thorén, AK
    et al.
    Legrand, Catherine
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Tonderski, K
    Temporal export of nitrogen from a constructed wetland: influence of hydrology and senescing submerged plants2004In: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 23, no 4-5, p. 233-249Article in journal (Refereed)
    Abstract [en]

    Nitrogen export was measured during monthly monitoring in an 18-ha constructed wetland in southeast Sweden 1998-2001. To investigate the influence of increased water flow on wetland nitrogen export, we performed intensive sampling (eight samples per day) of total-N, urea-N, NH4+-N, NO3--N in January-March 2001. Investigations of wetland plant distribution 1997-2001 and submerged plant biomass were combined with investigations of plant nitrogen content 1998-2001, to test the hypothesis that nitrogen export was linked to wetland plant decomposition. Nitrogen was exported from the wetland (3.3 kg N ha(-1) d(-1)), during the end of the intensive sampling period (19 February-12 March), coinciding with increased water flow (from 0.2 to 0.6 m(3) s(-1)). Plant cover expanded rapidly and nitrogen assimilated in the submerged plant community was estimated to be 39 kg ha(-1) in July 2001. After senescence in April the following year, plant biomass was reduced by 75%. We concluded that a significant part (40%) of this wetland nitrogen export might be associated with the release of organic and inorganic nitrogen from the senesced submerged plant community. Moreover, we hypothesize that nitrogen removal in wetlands in cold temperate climate may be limited by temporal nitrogen export induced by high water flow velocity when wetland plants are decomposing.

  • 105. Uronen, P
    et al.
    Kuuppo, P
    Legrand, Catherine
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Tamminen, T
    Allelopathic effects of toxic haptophyte Prymnesium parvum lead to release of dissolved organic carbon and increase in bacterial biomass2007In: Microbial Ecology, ISSN 0095-3628, E-ISSN 1432-184X, Vol. 54, no 1, p. 183-193Article in journal (Refereed)
    Abstract [en]

    The haptophyte Prymnesium parvum has lytic properties, and it affects coexisting phytoplankton species through allelopathy. We studied the effect of P. parvum allelo-chemicals on the lysis of the nontoxic and nonaxenic cryptomonad Rhodomonas salina and the consequent release of dissolved organic carbon (DOC). Changes in production, cell density, and biomass of associated bacteria were measured over 12 h. Six different combinations of P. parvum and R. salina cultures, their cell-and bacteria-free filtrates, and growth media as controls were used in the experiments. When P. parvum and R. salina cells were mixed, a significant increase in DOC concentration was measured within 30 min. Bacterial biomass increased significantly during the next 6 to 12 h when R. salina was mixed either with the P. parvum culture or the cell-free P. parvum filtrates (allelochemicals only). In contrast, bacterial biomass did not change in the treatments without the allelopathic action (without R. salina cells). Blooms of P. parvum alter the functioning of the planktonic food web by increasing carbon transfer through the microbial loop. In addition, P. parvum may indirectly benefit from the release of DOC as a result of its ability to ingest bacteria, by which it can acquire nutrients during limiting conditions.

  • 106. Uronen, P
    et al.
    Lehtinen, S
    Legrand, Catherine
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Kuuppo, P
    Tamminen, T
    Haemolytic activity and allelopathy of the haptophyte Prymnesium parvum in nutrient-limited and balanced growth conditions2005In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 299, p. 137-148Article in journal (Refereed)
    Abstract [en]

    Prymnesium parvum (Haptophyceae) was grown in 3 different nutrient treatments in semi-continuous cultures, where the N:P molar ratios were modified to 80:1, 4:1 and 16:1. The nutrient concentrations in the media affected the cellular nutrient content of P parvum. The phosphorus content showed larger flexibility in the cells and determined more the cellular nutrient ratios than nitrogen or carbon. Toxicity was measured as haemolytic activity 14 times during the culturing, All the cultures were toxic during the exponential growth, but toxicity increased in the nutrient limited cultures during semi-continuous dilution. The allelopathic effect of P parvum was examined with low cell densities (final abundance 2 and 5 x 10(3) cells ml(-1)) on cryptomonad Rhodomonas salina. With lower cell density, cell structures of R. salina were damaged in one-third of the cells and the cell density decreased slightly. With higher P. parvum cell density, less than half of the R. salina cells remained in the nutrient limited cultures after 23 h. P. parvum grown in nutrient balanced cultures negatively affected R. salina cells. The cellular N:P ratio, which was scaled to the Redfield ratio, could explain 67 and 75% of the variation in the haemolytic activity and the allelopathic effect, respectively. Our results confirm the hypothesis that nutrient deficiency increases toxicity of P. parvum. The haemolytic activity varied during semi-continuous culturing, but it was significantly dependent on intracellular N:P ratios. Due to the allelopathic effect, formation of a P. parvum bloom may accelerate after a critical cell density is reached when the competing species are eliminated.

  • 107.
    Weissbach, Astrid
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Bechemin, Christian
    French research Institute for the exploitation of the sea (Ifremer), L`Houmeau, France.
    Genauzeau, Sylvie
    French research Institute for the exploitation of the sea (Ifremer), L`Houmeau, France.
    Rudström, Maria
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Legrand, Catherine
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences. Alfred Wegener Institute for Polar and Marine Research, Germany.
    Impact of Alexandrium tamarense allelochemicals on DOM dynamics in an estuarine microbial community2012In: Harmful Algae, ISSN 1568-9883, E-ISSN 1878-1470, Vol. 13, p. 58-64Article in journal (Refereed)
    Abstract [en]

    Plankton and dissolved organic carbon (DOC) dynamics in fractionated estuarine microbial communities (<150 μm, <60 μm and <20 μm), incubated with allelopathic (lytic) or non allelopathic (non-lytic) Alexandrium tamarense filtrates were investigated over a period of 48 h. Additionally, the amount of dissolved organic matter (DOM) available for bacterial growth in the treatments was measured via bacterial seawater culture experiments immediately and 6 h after addition of A. tamarense filtrates. The lack of effect on DOC concentrations and plankton community composition in lytic treatments indicated that allelochemicals did not inhibit the growth of the microbial community. Nevertheless, bacterial seawater culture experiments provided evidence that lytic filtrate addition provoked the release of bioavailable DOM from the microbial community. Since DOM was only released from the largest seawater fraction, microorganisms >60 μm were probably most sensitive towards allelochemicals.

  • 108.
    Weissbach, Astrid
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Legrand, Catherine
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Effect of different salinities on growth and intra- and extracellular toxicity of four strains of the haptophyte Prymnesium parvum2012In: Aquatic Microbial Ecology, ISSN 0948-3055, E-ISSN 1616-1564, Vol. 67, no 2, p. 139-149Article in journal (Refereed)
    Abstract [en]

    The present study investigates the effect of brackish (7 PSU) and marine (26 PSU) salinity on physiological parameters and intra- and extracellular toxicity in 4 strains of Prymnesium parvum Carter. The different P. parvum strains were grown in batch cultures in 2 trials under different experimental conditions to test the development of intra- and extracellular toxicity during growth. The response of P. parvum toxicity to salinity was validated using 2 protocols. Intra-specific variations in growth rate, maximal cell density (yield) and cell morphology were controlled by salinity. Extracellular toxicity was higher at 7 PSU in all strains, but no correlation was found between intra- and extracellular toxicity. The variation of extracellular toxicity in response to salinity was much greater than that of intracellular toxicity, which indicates that P. parvum may be producing a variety of substances contributing to its various types of 'toxicity'.

  • 109.
    Weissbach, Astrid
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Legrand, Catherine
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Hemolytic activity, allelopathy and growth rates of four strains of Prymnesium parvumManuscript (preprint) (Other academic)
  • 110.
    Weissbach, Astrid
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Rudström, Maria
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Olofsson, Martin
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Bechemin, Christian
    IFREMER, France.
    Icely, John D
    Sagremarisco, Portugal.
    Newton, Alice
    Norwegian Institute for Air Research NIVA.
    Tillmann, Urban
    Alfred Wegener Institute for Polar and Marine Research, Germany.
    Legrand, Catherine
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Phytoplankton allelochemical interactions change microbial food web dynamics2011In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 56, no 3, p. 899-909Article in journal (Refereed)
    Abstract [en]

    This study investigates the effect of filtrates from an allelopathic dinoflagellate, Alexandrium tamarense, onfour microbial food webs that have been manipulated experimentally from natural seawater by modifying theavailability of resources in the form of dissolved organic carbon with additions of peptone, and by altering thegrazing pressure with size fractionation. Bacterial production was generally not affected by allelochemicals, butbacteria showed higher net growth in all food webs when allelochemicals were added, whereas heterotrophicnanoflagellates . 7 mm and ciliates were constrained in all food webs. Allelochemicals had the largest negativeeffects on microbial communities with low grazing pressure. In food webs with high grazing pressure andadditional resources, phytoplankton and small nanoflagellates were positively affected by the addition ofallelochemicals, suggesting that those were interfering with trophic interactions in the microbial communities. Bythe lysis of organisms sensitive towards allelochemicals, resources are made available and grazing pressure oncertain microorganisms is reduced. However, the intensity of these interactions is modulated by both theavailability of resources and the biomass of grazers in the initial food web.

  • 111.
    Weissbach, Astrid
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Tillmann, Urban
    Legrand, Catherine
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Allelopathic potential of the dinoflagellate Alexandrium tamarense on marine microbial communities2010In: Harmful Algae, ISSN 1568-9883, E-ISSN 1878-1470, Vol. 10, no 1, p. 9-18Article in journal (Refereed)
    Abstract [en]

    The impacts of two strains of the dinoflagellate Alexandrium tamarense, differing in lytic activity, on the abundance and the composition of microbial communities (<150 μm) were studied in North Sea water during spring with Phaeocystis globosa as a dominant species. Cell-free suspensions (supernatant) of exponentially growing lytic and non-lytic Alexandrium culture were added at different concentrations to natural microbial communities under nutrient rich conditions. The non-lytic strain had a positive impact on diatoms whereas the lytic strain suppressed phytoplankton growth in comparison to the control. P. globosa, present as single cells in the initial community, increased in abundance and formed colonies in all treatments. However, total abundance and number of colonies was low with lytic Alexandriumadditions, whereas shape of the colonies, but not abundance of cells, was affected by non-lytic Alexandrium additions. During the 4-day experiment, bacterial abundance was constantly higher with high lytic additions (highest concentration equivalent to 1000 cells ml−1) whereas nanoflagellate abundance in the same treatments was found to be lower at the end of the experiment. Initial bacterial community composition differed significantly among lytic Alexandrium, non-lyticAlexandrium and North Sea water. However, neither bacterial activity nor composition was significantly affected by the supernatants after 96 h. Our results indicated that Alexandrium allelochemicals do not inhibit growth and production of bacteria in seawater collected during spring in the North Sea.

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  • 112.
    Wells, Mark L.
    et al.
    Univ Maine, USA;Minist Nat Resources, China.
    Karlson, Bengt
    Swedish Meteorological and Hydrological Institute, Sweden, Sweden.
    Wulff, Angela
    University of Gothenburg, Sweden.
    Kudela, Raphael
    Univ Calif Santa Cruz, USA.
    Trick, Charles
    Western Univ, Canada;Schulich Sch Med & Dent, Canada.
    Asnaghi, Valentina
    Univ Genova DiSTAV, Italy.
    Berdalet, Elisa
    CSIC, Spain.
    Cochlan, William
    San Francisco State Univ, USA.
    Davidson, Keith
    Scottish Assoc Marine Sci, UK.
    De Rijcke, Maarten
    Flanders Marine Inst VLIZ, Belgium.
    Dutkiewicz, Stephanie
    MIT, USA.
    Hallegraeff, Gustaaf
    Univ Tasmania, Australia.
    Flynn, Kevin J.
    Swansea Univ, UK.
    Legrand, Catherine
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Paerl, Hans
    Univ North Carolina Chapel Hill, USA.
    Silke, Joe
    Marine Inst, Ireland.
    Suikkanen, Sanna
    Marine Res Ctr, Finland.
    Thompson, Peter
    CSIRO, Australia.
    Trainer, Vera L.
    NOAA, USA.
    Future HAB science: Directions and challenges in a changing climate2020In: Harmful Algae, ISSN 1568-9883, E-ISSN 1878-1470, Vol. 91, p. 1-18, article id 101632Article in journal (Refereed)
    Abstract [en]

    There is increasing concern that accelerating environmental change attributed to human-induced warming of the planet may substantially alter the patterns, distribution and intensity of Harmful Algal Blooms (HABs). Changes in temperature, ocean acidification, precipitation, nutrient stress or availability, and the physical structure of the water column all influence the productivity, composition, and global range of phytoplankton assemblages, but large uncertainty remains about how integration of these climate drivers might shape future HABs. Presented here are the collective deliberations from a symposium on HABs and climate change where the research challenges to understanding potential linkages between HABs and climate were considered, along with new research directions to better define these linkages. In addition to the likely effects of physical (temperature, salinity, stratification, light, changing storm intensity), chemical (nutrients, ocean acidification), and biological (grazer) drivers on microalgae (senso lato), symposium participants explored more broadly the subjects of cyanobacterial HABs, benthic HABs, HAB effects on fisheries, HAB modelling challenges, and the contributions that molecular approaches can bring to HAB studies. There was consensus that alongside traditional research, HAB scientists must set new courses of research and practices to deliver the conceptual and quantitative advances required to forecast future HAB trends. These different practices encompass laboratory and field studies, long-term observational programs, retrospectives, as well as the study of socioeconomic drivers and linkages with aqua culture and fisheries. In anticipation of growing HAB problems, research on potential mitigation strategies should be a priority. It is recommended that a substantial portion of HAB research among laboratories be directed collectively at a small sub-set of HAB species and questions in order to fast-track advances in our understanding. Climate-driven changes in coastal oceanographic and ecological systems are becoming substantial, in some cases exacerbated by localized human activities. That, combined with the slow pace of decreasing global carbon emissions, signals the urgency for HAB scientists to accelerate efforts across disciplines to provide society with the necessary insights regarding future HAB trends.

  • 113.
    Wolanski, E
    et al.
    Australian Institute of Marine Science, Australia.
    Newton, A
    Universidade do Algarve, Portugal.
    Rabalais, N
    Louisiana Universities Marine Consortium, USA.
    Legrand, Catherine
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Coastal Zone Management2013In: Reference Module in Earth Systems and Environmental Sciences / [ed] Scott A. Elias (editor in chief), Oxford: Elsevier, 2013Chapter in book (Other academic)
    Abstract [en]

    This article presents a scientific overview of the processes and the impact of environmental degradation of coastal waters due to human activities on the adjoining land. The direct effects range from eutrophication and harmful algal blooms, to hypoxia and anoxia. The indirect effects are more subtle and can also lead to the collapse of the ecosystem as in the case of coral reefs or seagrass meadows. Engineering solutions alone are not available to prevent this degradation that can only be reversed, or prevented, using a basin-wide ecohydrology approach.

  • 114. Wolanski, E
    et al.
    Rabalais, N
    Newton, A
    Legrand, Catherine
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Ecohydrology of coastal waters, boundaries and limitations2008Other (Other academic)
123 101 - 114 of 114
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