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  • 601. Weich, R G
    et al.
    Granéli, Edna
    Department of Marine Ecology, University of Lund.
    Extracellular alkaline phosphatase activity in Ulva lactuca L1989Ingår i: Journal of Experimental Marine Biology and Ecology, ISSN 0022-0981, E-ISSN 1879-1697, Vol. 129, nr 1, s. 33-44Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Extracellular alkaline phosphatase activity (APA) was detected in the marine macroalga Ulva lactuca, cultivated in laboratory conditions under phosphate limitation. Algal discs were grown in continuous light and in darkness for a maximum of 205 h in sterilized seawater supplied with ammonium nitrate and various phosphate concentrations. APA and phosphate uptake in U. lactuca was stimulated in light whereas inhibition was detected in darkness. APA increased significantly during the cultivation in a phosphate-deficient medium but was suppressed at high external phosphate concentrations. In addition, pretreatment in penicillin over 48 h markedly enhanced enzyme activity during P limitation. The pretreatment in penicillin reduced the number of surface-associated bacteria. Our results indicate that APA in U. lactuca was dependent on the external phosphate concentration, energy from photophosphorylation and bacteria. Since intracellular polyphosphates and an orthophosphate pool still were displayed in 31P NMR spectra after cultivation at phosphate-limiting conditions, P deficiency was not suggested. Unfortunately, NMR spectra reflect total amounts of P compounds and local differences in the P status of the multicellular tissue could not be distinguished. Postulating a negative correlation between the P status and APA, a lower P status in meristematic areas during P limitation was suggested. Alkalisation of the growth medium during algal growth in light, and/or intracellular pH changes may additionally have affected enzyme production. 

  • 602.
    Weissbach, Astrid
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    The role of allelopathy in microbial food webs2011Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Phytoplankton produce allelochemicals; excreted chemical substances that are affecting other microorganisms in their direct environment.

    In my thesis, I investigated strain specific variability in the expression of allelochemicals of the harmful flagellate Prymnesium parvum, that is euryhaline but mainly bloom forming in brackish water. I found a large variation among strains, but further showed that all strains of P. parvum were more allelopathic in brackish water compared to marine water.

    In a marine microbial community, allelochemicals can affect prey, competitors and grazers both, directly and indirectly. For instance, in a food web where grazing controls prey abundance, the negative direct effect of allelochemicals on grazers will positive affect their prey. During my thesis, I investigated how marine microbial communities respond to the addition of allelochemicals. I performed field experiments with microbial communities from seawater collected from different places over Europe, and tested how this communities respond to the addition of allelochemicals from the dinoflagellate Alexandrium tamarense. Before I incubated the microbial communities for several days with A. tamarense algal filtrate, I evaluated the allelopathic efficiency of the algal filtrates with an algal monoculture of Rhodomonas spp. This allowed me to compare the effect of A. tamarense filtrate between the different microbial communities.

    In general, bacteria reached higher abundances when allelochemicals were present. As allelochemicals also inhibited nanoflagellates and ciliates, we concluded, that allelochemicals indirectly benefit bacteria by reducing grazing pressure. In microbial food webs with many heterotrophic grazers, allelochemicals further benefitted other phytoplankton by inhibiting grazers.

    It was also shown that bioavailable DOM is released from a microbial community when allelochemicals are present. As most DOM was released from the seawater fraction > 60 μm, we concluded, that larger microorganisms are more affected by allelochemicals than smaller microorganisms. The results can be explained by the surface to volume ratio of microorganisms: Larger organisms provide more contact surface for allelochemicals, and therefore, are probably more vulnerable towards allelochemicals.

    In conclusion, the effect of allelochemicals on a microbial community depends among others on the structure of the microbial food web, the amount of available DOM, the particle density in the seawater and the composition of the phytoplankton community.

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  • 603.
    Weissbach, Astrid
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    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
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Legrand, Catherine
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV. Alfred Wegener Institute for Polar and Marine Research, Germany.
    Impact of Alexandrium tamarense allelochemicals on DOM dynamics in an estuarine microbial community2012Ingår i: Harmful Algae, ISSN 1568-9883, E-ISSN 1878-1470, Vol. 13, s. 58-64Artikel i tidskrift (Refereegranskat)
    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.

  • 604.
    Weissbach, Astrid
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Legrand, Catherine
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Effect of different salinities on growth and intra- and extracellular toxicity of four strains of the haptophyte Prymnesium parvum2012Ingår i: Aquatic Microbial Ecology, ISSN 0948-3055, E-ISSN 1616-1564, Vol. 67, nr 2, s. 139-149Artikel i tidskrift (Refereegranskat)
    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'.

  • 605.
    Weissbach, Astrid
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Rudström, Maria
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Olofsson, Martin
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    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
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Phytoplankton allelochemical interactions change microbial food web dynamics2011Ingår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 56, nr 3, s. 899-909Artikel i tidskrift (Refereegranskat)
    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.

  • 606.
    Weissbach, Astrid
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Tillmann, Urban
    Legrand, Catherine
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Allelopathic potential of the dinoflagellate Alexandrium tamarense on marine microbial communities2010Ingår i: Harmful Algae, ISSN 1568-9883, E-ISSN 1878-1470, Vol. 10, nr 1, s. 9-18Artikel i tidskrift (Refereegranskat)
    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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  • 607.
    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
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    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 climate2020Ingår i: Harmful Algae, ISSN 1568-9883, E-ISSN 1878-1470, Vol. 91, s. 1-18, artikel-id 101632Artikel i tidskrift (Refereegranskat)
    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.

  • 608.
    Wen, Su
    et al.
    Univ Chinese Academy of Science.
    Hagström, Johannes
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Yuhong, Jia
    Chinese Acad Sci.
    Yaping, Lu
    Chinese Acad Sci.
    Fanxiang, Kong
    Chinese Acad Sci.
    Effects of rice straw on the cell viability, photosynthesis, and growth of Microcystis aeruginosa2014Ingår i: Chinese Journal of Oceanology and Limnology, ISSN 0254-4059, E-ISSN 1993-5005, Vol. 32, nr 1, s. 120-129Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Rice straw is supposed to be an environment-friendly biomaterial for inhibiting the growth of harmful blooms of the cyanobacterium Microcystis aeruginosa. However, its potential mechanism is not well known. To explore this mechanism, the growth, cell viability (esterase activity, membrane potential, and membrane integrity), photosynthesis, and cell size of M. aeruginosa were determined using flow cytometry and Phyto-PAM after exposure to rice straw extracts (RSE). The results show that doses from 2.0 to 10.0 g/L of RSE efficiently inhibited the alga for 15 days, while the physiologic and morphologic responses of the cyanobacteria were time-dependent. RSE interfered with the cell membrane potential, cell size, and in vivo chlorophyll-a fluorescence on the first day. After 7 days of exposure, RSE was transported into the cytosol, which disrupted enzyme activity and photosynthesis. The cyanobacteria then started to repair its physiology (enzyme activity, photosynthesis) and remained viable, suggesting that rice straw act as an algistatic agent.

  • 609.
    Wennersten, Lena
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Forsman, Anders
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Population-level consequences of polymorphism, plasticity and randomized phenotype switching: a review of predictions2012Ingår i: Biological Reviews, ISSN 1464-7931, E-ISSN 1469-185X, Vol. 87, nr 3, s. 756-767Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    The consequences of among-individual phenotypic variation for the performance and ecological success of populations and species has attracted growing interest in recent years. Earlier reviews of this field typically address the consequences for population processes of one specific source of variation (plasticity or polymorphism), or consider one specific aspect of population performance, such as rate of speciation. Here we take a broader approach and study earlier reviews in order to summarize and compare predictions regarding several population-level consequences of phenotypic variation stemming from genetic polymorphism, developmental plasticity or randomized phenotype switching. Unravelling cause-dependent consequences of variation may increase our ability to understand the ecological dynamics of natural populations and communities, develop more informed management plans for protection of biodiversity, suggest possible routes to increased productivity and yield in natural and managed biological systems, and resolve inconsistencies in patterns and results seen in studies of different model systems. We find an overall agreement regarding the effects of higher levels of phenotypic variation generated by different sources, but also some differences between fine-grained and coarse-grained environments, modular and unitary organisms, mobile and sessile organisms, and between flexible and fixed traits. We propose ways to test the predictions and identify issues where current knowledge is limited and future lines of investigation promise to provide important novel insights.

  • 610.
    Wennersten, Lena
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Karpestam, Einat
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Forsman, Anders
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Phenotype manipulation influences microhabitat choice in pygmy grasshoppers2012Ingår i: Current Zoology, ISSN 1674-5507, Vol. 58, nr 3, s. 392-400Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The matching habitat choice hypothesis posits that individuals actively choose those microhabitats that best match their specificphenotype to maximize fitness. Despite the profound implications, matching habitat choice has not been unequivocally demonstrated. Weconducted two experiments to examine the impact of pigmentation pattern in the color polymorphic pygmy grasshopper Tetrix subulata onhabitat choice in a laboratory thermal mosaic arena. We found no behavioral differences in the thermal mosaic among pygmy grasshoppersbelonging to either pale, intermediate or dark natural color morphs. However, after manipulating the grasshoppers’ phenotype, the utilizationthrough time of warmer and colder parts of the arena was different for black-painted and white-painted individuals. White-paintedindividuals used warmer parts of the arena, at least during the initial stage of the experiment. We conclude that microhabitat choicerepresents a form of behavioural plasticity. Thus, even if the choice itself is flexible and not genetically determined, it can still lead to spatialgenetic structure in the population because the phenotypes themselves may be genetically mediated

  • 611.
    Wille, Michelle
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Viruses on the wing: evolution and dynamics of influenza A virus in the Mallard reservoir2015Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis explores the evolution of avian influenza A viruses (IAV), as well as host-pathogen interactions between these viruses and their main reservoir host, the Mallard (Anas platyrhynchos). IAV is a genetically diverse, multi-host virus and wild birds, particularly dabbling ducks, are the natural reservoir. At our study site, up to 30% of migratory Mallards are infected with IAV during an autumn season, and host a large number of virus subtypes. IAV diversity is driven by two main mechanisms: mutation, driving genetic drift; and reassortment following co-infection, resulting in genetic shift.

     

    Reassortment is pervasive within an autumn season, both across multiple subtypes and within a single subtype. It is a key genetic feature in long-term maintenance of common subtypes, as it allows for independent lineage turn-over, generating novel genetic constellations. I hypothesize that the decoupling of successful constellations and generation of novel annual constellations enables viruses to escape herd immunity; these genetic changes must confer antigenic change for the process to be favourable. Indeed, in an experiment utilizing vaccines, circulating viruses escaped homosubtypic immunity, resulting in the proliferation of infections with the same subtype as the vaccine. While the host plays an important role in shaping IAV evolutionary genetics, one must consider that Mallards are infected with a multitude of other microorganisms. Here, Mallards were infected with IAV, gamma coronaviruses, and avian paramyxovirus type 1 simultaneously, and we found a putative synergistic interaction between IAV and gamma coronaviruses.

     

    Mallards occupy the interface between humans, poultry, and wild birds, and are the reservoir of IAV diversity. New incursions of highly pathogenic H5 viruses to both Europe and North America reaffirms the role of wild birds, particularly waterfowl, in diffusion of viruses spatially. Using European low pathogenic viruses and Mallard model, this thesis contributes to aspects of epidemiology, ecology, and evolutionary dynamics of waterfowl viruses, particularly IAV

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    Wille_Kappa_2015
  • 612.
    Wille, Michelle
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). Uppsala University.
    Latorre-Margalef, Neus
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). University of Georgia, USA.
    Tolf, Conny
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Stallknecht, D. E.
    University of Georgia, USA.
    Waldenström, Jonas
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    No evidence for homosubtypic immunity of influenza H3 in Mallards following vaccination in a natural experimental system2017Ingår i: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 26, nr 5, s. 1420-1431Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Mallard (Anas platyrhynchos) is an important reservoir species for influenza A viruses (IAV), and in this host, prevalence and virus diversity are high. Studies have demonstrated the presence of homosubtypic immunity, where individuals are unlikely to be reinfected with the same subtype within an autumn season. Further, evidence for heterosubtypic immunity exists, whereby immune responses specific for one subtype offer partial or complete protection against related HA subtypes. We utilized a natural experimental system to determine whether homo- or heterospecific immunity could be induced following experimental vaccination. Thirty Mallards were vaccinated with an inactivated H3, H6 or a sham vaccine and after seroconversion were exposed to naturally infected wild conspecifics. All ducks were infected within 2days and had both primary and secondary infections. Overall, there was no observable difference between groups; all individuals were infected with H3 and H10 IAV. At the cessation of the experiment, most individuals had anti-NP antibodies and neutralizing antibodies against H10. Not all individuals had H3 neutralizing antibodies. The isolated H3 IAVs revealed genetic dissimilarity to the H3 vaccine strain, specifically substitutions in the vicinity of the receptor-binding site. There was no evidence of vaccine-induced homosubtypic immunity to H3, a likely result of both a poor H3 immune response in the ducks and H3 immune escape. Likewise, there was no observed heterosubtypic protection related to H6 vaccination. This study highlights the need for experimental approaches to assess how exposure to pathogens and resulting immune processes translates to individual and population disease dynamics.

  • 613.
    Williams, C. M.
    et al.
    Univ Georgia, USA.
    Dupont, A. M.
    Univ Georgia, USA.
    Loevenich, J.
    Univ Georgia, USA.
    Post, A. F.
    URI, USA.
    Dinasquet, Julie
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). Univ Copenhagen, Denmark.
    Yager, P. L.
    Univ Georgia, USA.
    Pelagic microbial heterotrophy in response to a highly productive bloom of Phaeocystis antarctica in the Amundsen Sea Polynya, Antarctica2016Ingår i: Elementa: Science of the Anthropocene, E-ISSN 2325-1026, Vol. 4, s. 1-18, artikel-id 000102Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Heterotrophic bacteria play a key role in marine carbon cycling, and understanding their activities in polar systems is important for considering climate change impacts there. One goal of the ASPIRE project was to examine the relationship between the phytoplankton bloom and bacterial heterotrophy in the Amundsen Sea Polynya (ASP). Bacterial abundance, production (BP), respiration, growth efficiency, and extracellular enzyme activity (EEA) were compared to nutrient and organic matter inventories, chlorophyll a (Chl a), viral and microzooplankton abundance, and net primary production (NPP). Bacterial production and respiration clearly responded (0.04-4.0 and 10-53 mu g C L-1 d(-1), respectively) to the buildup of a massive Phaeocystis antarctica bloom (Chl a: 0.2-22 mu g L-1), with highest rates observed in the central polynya where Chl a and particulate organic carbon (POC) were greatest. The highest BP rates exceeded those reported for the Ross Sea or any other Antarctic coastal system, yet the BP: NPP ratio (2.1-9.4%) was relatively low. Bacterial respiration was also high, and growth efficiency (2-27%; median = 10%) was similar to oligotrophic systems. Thus, the integrated bacterial carbon demand (0.8-2.8 g C m(-2) d(-1)) was a high fraction (25-128%; median = 43%) of NPP during bloom development. During peak bloom, activity was particle-associated: BP and EEA correlated well with POC, and size fractionation experiments showed that the larger size fraction (> 3 mu m) accounted for a majority (similar to 75%) of the BP. The community was psychrophilic, with a 5x reduction in BP when warmed to 20 degrees C. In deeper waters, respiration remained relatively high, likely fueled by the significant downward particle flux in the region. A highly active, particle-associated, heterotrophic microbial community clearly responded to the extraordinary phytoplankton bloom in the ASP, likely limiting biological pump efficiency during the early season.

  • 614.
    Williams, Richard A. J.
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). Univ Kansas, USA.;Univ Complutense Madrid, Spain.
    Owens, Hannah L.
    Univ Kansas, USA;Univ Florida, USA.
    Clamp, John
    North Carolina Cent Univ, USA.
    Peterson, A. Townsend
    Univ Kansas, USA.
    Warren, Alan
    Nat Hist Museum, UK.
    Martin-Cereceda, Mercedes
    Univ Complutense Madrid, Spain.
    Endemicity and climatic niche differentiation in three marine ciliated protists2018Ingår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 63, nr 6, s. 2727-2736Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The biogeographic pattern of single-celled eukaryotes (protists), including ciliates, is poorly understood. Most marine species are believed to have a relatively high dispersal potential, such that both globally distributed and geographically isolated taxa exist. Primary occurrence data for three large, easily identified ciliate species, Parafavella gigantea, Schmidingerella serrata, and Zoothamnium pelagicum, and environmental data drawn from the National Oceanic and Atmospheric Administration's World Ocean Atlas were used to estimate each species' spatial and environmental distributions using Maxent v3.3.3k. The predictive power of the models was tested with a series of spatial stratification studies, which were evaluated using partial receiver operating characteristic (ROC) statistics. Differences between niches occupied by each taxon were evaluated using background similarity tests. All predictions showed significant ability to anticipate test points. The null hypotheses of niche similarity were rejected in all background similarity tests comparing the niches among the three species. This article provides the first quantitative assessment of environmental conditions associated with three species of ciliates and a first estimate of their spatial distributions in the North Atlantic, which can serve as a benchmark against which to document distributional shifts. These species follow consistent, predictable patterns related to climate and environmental biochemistry; the importance of climatic conditions as regards protist distributions is noteworthy considering the effects of global climate change.

  • 615.
    Williams, Richard A. J.
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Tolf, Conny
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Waldenström, Jonas
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Molecular identification of papillomavirus in ducks2018Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, artikel-id 9096Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Papillomaviruses infect many vertebrates, including birds. Persistent infections by some strains can cause malignant proliferation of cells (i.e. cancer), though more typically infections cause benign tumours, or may be completely subclinical. Sometimes extensive, persistent tumours are recorded-notably in chaffinches and humans. In 2016, a novel papillomavirus genotype was characterized from a duck faecal microbiome, in Bhopal, India; the sixth papillomavirus genotype from birds. Prompted by this finding, we screened 160 cloacal swabs and 968 faecal samples collected from 299 ducks sampled at Ottenby Bird Observatory, Sweden in 2015, using a newly designed real-time PCR. Twenty one samples (1.9%) from six individuals (2%) were positive. Eighteen sequences were identical to the published genotype, duck papillomavirus 1. One additional novel genotype was recovered from three samples. Both genotypes were recovered from a wild strain domestic mallard that was infected for more than 60 days with each genotype. All positive individuals were adult (P = 0.004). Significantly more positive samples were detected from swabs than faecal samples (P < 0.0001). Sample type data suggests transmission may be via direct contact, and only infrequently, via the oral-faecal route. Infection in only adult birds supports the hypothesis that this virus is sexually transmitted, though more work is required to verify this.

  • 616.
    Williamson, Craig E.
    et al.
    Miami University, USA.
    Neale, Patrick J.
    Smithsonian Environmental Research Center, USA.
    Hylander, Samuel
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Rose, Kevin C.
    Rensselaer Polytechnic Institute, USA.
    Figueroa, Félix L.
    University of Malaga, Spain.
    Robinson, Sharon A.
    University of Wollongong, Australia.
    Häder, Donat-P.
    Friedrich-Alexander Universität, Germany.
    Wängberg, Sten-Åke
    University of Gothenburg, Sweden.
    Worrest, Robert C.
    Columbia University, USA.
    The interactive effects of stratospheric ozone depletion, UV radiation, and climate change on aquatic ecosystems2019Ingår i: Photochemical and Photobiological Sciences, ISSN 1474-905X, E-ISSN 1474-9092, Vol. 18, nr 3, s. 717-746Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This assessment summarises the current state of knowledge on the interactive effects of ozone depletion and climate change on aquatic ecosystems, focusing on how these affect exposures to UV radiation in both inland and oceanic waters. The ways in which stratospheric ozone depletion is directly altering climate in the southern hemisphere and the consequent extensive effects on aquatic ecosystems are also addressed. The primary objective is to synthesise novel findings over the past four years in the context of the existing understanding of ecosystem response to UV radiation and the interactive effects of climate change. If it were not for the Montreal Protocol, stratospheric ozone depletion would have led to high levels of exposure to solar UV radiation with much stronger negative effects on all trophic levels in aquatic ecosystems than currently experienced in both inland and oceanic waters. This “world avoided” scenario that has curtailed ozone depletion, means that climate change and other environmental variables will play the primary role in regulating the exposure of aquatic organisms to solar UV radiation. Reductions in the thickness and duration of snow and ice cover are increasing the levels of exposure of aquatic organisms to UV radiation. Climate change was also expected to increase exposure by causing shallow mixed layers, but new data show deepening in some regions and shoaling in others. In contrast, climate-change related increases in heavy precipitation and melting of glaciers and permafrost are increasing the concentration and colour of UV-absorbing dissolved organic matter (DOM) and particulates. This is leading to the “browning” of many inland and coastal waters, with consequent loss of the valuable ecosystem service in which solar UV radiation disinfects surface waters of parasites and pathogens. Many organisms can reduce damage due to exposure to UV radiation through behavioural avoidance, photoprotection, and photoenzymatic repair, but meta-analyses continue to confirm negative effects of UV radiation across all trophic levels. Modeling studies estimating photoinhibition of primary production in parts of the Pacific Ocean have demonstrated that the UV radiation component of sunlight leads to a 20% decrease in estimates of primary productivity. Exposure to UV radiation can also lead to positive effects on some organisms by damaging less UV-tolerant predators, competitors, and pathogens. UV radiation also contributes to the formation of microplastic pollutants and interacts with artificial sunscreens and other pollutants with adverse effects on aquatic ecosystems. Exposure to UV-B radiation can decrease the toxicity of some pollutants such as methyl mercury (due to its role in demethylation) but increase the toxicity of other pollutants such as some pesticides and polycyclic aromatic hydrocarbons. Feeding on microplastics by zooplankton can lead to bioaccumulation in fish. Microplastics are found in up to 20% of fish marketed for human consumption, potentially threatening food security. Depletion of stratospheric ozone has altered climate in the southern hemisphere in ways that have increased oceanic productivity and consequently the growth, survival and reproduction of many sea birds and mammals. In contrast, warmer sea surface temperatures related to these climate shifts are also correlated with declines in both kelp beds in Tasmania and corals in Brazil. This assessment demonstrates that knowledge of the interactive effects of ozone depletion, UV radiation, and climate change factors on aquatic ecosystems has advanced considerably over the past four years and confirms the importance of considering synergies between environmental factors.

  • 617.
    Wilson, Samuel T.
    et al.
    University of Hawai‘i at Manoa, USA.
    Barone, Benedetto
    University of Hawai‘i at Manoa, USA.
    Ascani, Francois
    University of Hawai‘i at Manoa, USA ; University of Hawai‘i at Hilo, USA.
    Bidigare, Robert R.
    University of Hawai‘i at Manoa, USA ; University of Hawai‘i, USA.
    Church, Matthew J.
    University of Hawai‘i at Manoa, USA.
    Del Valle, Daniela A.
    University of Hawai‘i at Manoa, USA.
    Dyhrman, Sonya T.
    University of Hawai‘i at Manoa, USA ; Columbia University, USA.
    Ferrón, Sara
    University of Hawai‘i at Manoa, USA.
    Fitzsimmons, Jessica N.
    University of Hawai‘i at Manoa, USA.
    Juranek, Laurie W.
    Oregon State University, USA.
    Kolber, Z. S.
    Letelier, R. M.
    Martínez-García, Sandra
    University of Hawai‘i at Manoa, USA.
    Nicholson, D. P.
    Richards, K. J.
    Rii, Y. M.
    Rouco, M.
    Viviani, D. A.
    White, A. E.
    Zehr, J. P.
    Karl, D. M.
    Short-term variability in euphotic zone biogeochemistry and primary productivity at Station ALOHA: A case study of summer 20122015Ingår i: Global Biogeochemical Cycles, ISSN 0886-6236, E-ISSN 1944-9224, Vol. 29, nr 8, s. 1145-1164Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Time-series observations are critical to understand the structure, function, and dynamics of marine ecosystems. The Hawaii Ocean Time-series program has maintained near-monthly sampling at Station ALOHA (22°45′N, 158°00′W) in the oligotrophic North Pacific Subtropical Gyre (NPSG) since 1988 and has identified ecosystem variability over seasonal to interannual timescales. To further extend the temporal resolution of these near-monthly time-series observations, an extensive field campaign was conducted during July-September 2012 at Station ALOHA with near-daily sampling of upper water-column biogeochemistry, phytoplankton abundance, and activity. The resulting data set provided biogeochemical measurements at high temporal resolution and documents two important events at Station ALOHA: (1) a prolonged period of low productivity when net community production in the mixed layer shifted to a net heterotrophic state and (2) detection of a distinct sea-surface salinity minimum feature which was prominent in the upper water column (0-50 m) for a period of approximately 30 days. The shipboard observations during July-September 2012 were supplemented with in situ measurements provided by Seagliders, profiling floats, and remote satellite observations that together revealed the extent of the low productivity and the sea-surface salinity minimum feature in the NPSG.

  • 618. Witzgall, P
    et al.
    Trematerra, P
    Liblikas, Ilme
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Bengtsson, M
    Unelius, C. Rikard
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Pheromone communication channels in tortricid moths: lower specificity of alcohol vs. acetate geometric isomer blends2010Ingår i: Bulletin of entomological research, ISSN 0007-4853, E-ISSN 1475-2670, Vol. 100, nr 2, s. 225-230Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Discrimination of conspecific and heterospecific signals is a key element in the evolution of specific mate recognition systems. Lepidopteran pheromone signals are typically composed of several compounds that synergize attraction of conspecific and inhibit attraction of heterospecific males. Blends convey specificity, but not their single components, that are typically shared by several species. Many sex pheromones are blends of geometric or positional isomers of straight-chain acetates, while species-specific blends of analogous alcohols have not been described. We have, therefore, studied the attraction of tortricid moths to the geometric isomers (E,E)-, (E,Z)-, (Z,E)- and (Z,Z)-8,10-dodecadien-1-ol. Only one species responding to these alcohols seemed to be attracted to a blend of two isomers, while most species are attracted to only one alcohol isomer. Lack of a pronounced synergist or antagonist effect of the other geometric isomers explains the lack of specific attraction to isomer blends and reduces accordingly the number of specific communication signals composed of these alcohols. In comparison, many more species respond to the analogous (E,E)-, (E,Z)-, (Z,E)- and (Z,Z)-8,10-dodecadienyl acetates and their binary blends. The acetate isomers all play a behavioural role, either as attractants, attraction synergists or antagonists, and thus promote specific communication with acetate blends. Male moths seem to discriminate the acetate isomers with greater precision than the analogous alcohols. It is proposed that discrimination is facilitated by steric differences between the four acetate isomers, as compared to the more uniform steric properties of the alcohols.

  • 619. Woin, P
    et al.
    Larsson, Per
    Department of Ecology, Limnology, University of Lund.
    Phthalate esters reduce predation efficiency of dragonfly larvae (Odonata; Aeshna)1987Ingår i: Bulletin of Environmental Contamination and Toxicology, ISSN 0007-4861, E-ISSN 1432-0800, Vol. 38, nr 2, s. 220-225Artikel i tidskrift (Refereegranskat)
  • 620.
    Wolf, Annett
    Linnéuniversitetet, Universitetsförvaltningen. Forest Ecology, Institute of Terrestrial Ecosystems, Department of Environmental Science, ETH Zurich, Universitätsstrasse 16, CH-8092 Zurich, Switzerland.
    Estimating the potential impact of vegetation on the water cycle requires accurate soil water parameter estimation2011Ingår i: Ecological Modelling, ISSN 0304-3800, E-ISSN 1872-7026, Vol. 222, nr 15, s. 2595-2605Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It is well known that vegetation dynamics at the catchment scale depends on the prevailing weather and soil moisture conditions. Soil moisture, however, is not equally distributed in space due to differences in topography, weather patterns, soil properties and the type and amount of vegetation cover. To elucidate the complex interaction between vegetation and soil moisture, the dynamic vegetation model LPJ-GUESS (Smith et al., 2001), which provides estimations of vegetation dynamics, but does not consider lateral water fluxes was coupled with the hydrological TOPMODEL (cf. Beven, 2001) in order to be able to evaluate the importance of these lateral fluxes. The new model LG-TM was calibrated and validated in two climatically different mountain catchments. The estimations of runoff were good, when monthly and weekly time scales were considered, although the low flow periods at winter time were somewhat underestimated. The uncertainty in the climate induced change vegetation carbon storage caused by the uncertainty in soil parameters was up to 3–5 kg C m−2 (depending on elevation and catchment), compared to the total change in vegetation carbon storage of 5–9 kg C m−2. Therefore accurate estimates of the parameters influencing the water holding capacity of the soil, for example depth and porosity, are necessary when estimating future changes in vegetation carbon storage. Similarly, changes in plant transpiration due to climatic changes could be almost double as high (88 mm m−2) in the not calibrated model compared to the new model version (ca 50 mm m−2 transpiration change). The uncertainties in these soil properties were found to be more important than the lateral water exchange between grid cells, even in steep topography at least for the temporal and spatial resolution used here.

  • 621. Worm, Boris
    et al.
    Lotze, Heike K.
    Boström, Christoffer
    Engkvist, Roland
    Högskolan i Kalmar, Naturvetenskapliga institutionen.
    Labanauskas, Vytautas
    Sommer, Ulrich
    Marine diversity shift linked to interactions among grazers, nutrients and propagule banks1999Ingår i: Marine Ecology Progress Series, ISSN 0171-8630, Vol. 185, s. 309-314Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Diverse coastal seaweed communities dominated by perennial fucoids become replaced by species-poor turfs of annual algae throughout the Baltic Sea. A large scale field survey and factorial field experiments indicated that grazers maintain the fucoid cornmunity through selective consumption of annual algae. Interactive effects between grazers and dormant propagules of annual algae. stored in a 'marine seed bank', determine the response of this system to anthropogenic nutrient loading. Nutrients override grazer control and accelerate the loss of algal diversity in the presence but not in the absence of a propagule bank. This irnplies a novel role of propagule banks for community regulation and ecosystem response to manne eutrophication.

     

  • 622.
    Wu, Xiaofen
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Structure and function of microbial communities in acid sulfate soil and the terrestrial deep biosphere2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis describes the use of different DNA sequencing technologies to investigate the structure and function of microbial communities in two extreme environments, boreal acid sulfate soil and the terrestrial deep biosphere.

    The first of the two investigated environments was soils containing un-oxidized metal sulfides that are termed ‘potential acid sulfate soil’ (PASS) materials. If these materials are exposed to atmospheric oxygen by either natural phenomena (e.g., land uplift) or human activities (e.g., drainage) then the metal sulfides become oxidized and the PASS becomes acidic and is defined as an ‘acid sulfate soil’ (ASS). The resulting acid and metal release from metal sulfide oxidation can lead to severe environmental damage. Although acidophilic microorganisms capable of catalyzing acid and metal release have been identified from many sulfide mineral containing environments, the microbial community of boreal PASSs/ASSs remains unclear. This study investigated the physicochemical and microbial characteristics of PASSs and ASSs from the Risöfladan experimental field in Vasa, Finland. Sanger sequencing of 16S rRNA gene sequences of microorganisms present in the PASSs and ASSs were mostly assigned to acidophilic species and environmental clones previously identified from acid- and metal-contaminated environments. Enrichment cultures inoculated from the ASS demonstrated that the acidophilic microorganisms were responsible for catalyzing acid and metal release from PASSs/ASSs. Lastly, the study investigated how to mitigate metal sulfide oxidation and the concomitant formation of sulfuric acid by treating ASSs in situ with CaCO3 or Ca(OH)2 suspensions. The DNA sequencing still identified acidophilic microorganisms after the chemical treatments. However, the increased pH during and after treatment suggested that the activity of the acidophiles might be inhibited. This study was the first to identify the microbial community present in boreal PASSs/ASSs and suggested that treatment with basic compounds may inhibit microbial catalysis of metal sulfide dissolution.

    The second studied environment was the deep, dark terrestrial subsurface that is suggested to be both extremely stable and highly oligotrophic. Despite the scarcity of carbon and energy sources, the deep biosphere is estimated to constitute up to 20% of the total biomass on earth and thus, represents the largest microbial ecosystem. However, due to the difficulties of accessing this environment and our inability to cultivate the indigenous microbial populations, details of the diversity and metabolism of these communities remain largely unexplored. This study was carried out at Äspö Hard Rock Laboratory, Sweden and utilized second-generation sequencing to identify the taxonomic composition and genetic potential of planktonic and biofilm populations. Community DNA sequencing of planktonic cells from three water types at varied age and depth (‘modern marine’, ‘undefined mixed’, and ‘old saline’) showed the existence of ultra-small cells capable of passing through a 0.22 μm filter that were phylogenetically distinct communities from the >0.22 μm fraction. The reduced cell size and/or genome size suggested a potential adaptation to the oligotrophic environment in the terrestrial deep biosphere. The identified planktonic communities were dominated by Proteobacteria, Candidate divisions, unclassified archaea, and unclassified bacteria. Functional analysis of the assembled genomes showed that the planktonic population from the shallow modern marine water demonstrated a predominantly anaerobic and heterotrophic lifestyle. In contrast, the deeper, old saline water was more closely aligned with the hypothesis of a hydrogen-driven deep biosphere. Metagenomic analysis of subsurface biofilms from ‘modern marine’ and ‘old saline’ water types suggested only a subset of populations were involved in initial biofilm formation. The identified biofilm populations from both water types were distinct from the planktonic community and were suggested to be dominated by hydrogen fed, chemolithoautotrophic and diazotrophic populations.

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  • 623.
    Yager, P. L.
    et al.
    Univ Georgia, USA.
    Sherrell, R. M.
    Rutgers State Univ, USA.
    Stammerjohn, S. E.
    Univ Colorado, USA.
    Ducklow, H. W.
    Columbia Univ, USA.
    Schofield, O. M. E.
    Rutgers State Univ, USA.
    Ingall, E. D.
    Georgia Inst Technol, USA.
    Wilson, S. E.
    Bangor Univ, UK.
    Lowry, K. E.
    Stanford Univ, USA.
    Williams, C. M.
    Univ Georgia, USA.
    Riemann, Lasse
    Univ Copenhagen, Denmark.
    Bertilsson, S.
    Uppsala University.
    Alderkamp, A-C
    Stanford Univ, USA.
    Dinasquet, Julie
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). Univ Copenhagen, Denmark.
    Logares, R.
    CSIC, Spain.
    Richert, I.
    Uppsala University.
    Sipler, R. E.
    Coll William & Mary, USA.
    Melara, A. J.
    Univ Georgia, USA.
    Mu, L.
    Univ Georgia, USA.
    Newstead, R. G.
    Bangor Univ, UK.
    Post, A. F.
    Florida Atlantic Univ, USA.
    Swalethorp, R.
    Tech Univ Denmark, Denmark;University of Gothenburg.
    van Dijken, G. L.
    Stanford Univ, USA.
    A carbon budget for the Amundsen Sea Polynya, Antarctica: Estimating net community production and export in a highly productive polar ecosystem2016Ingår i: Elementa: Science of the Anthropocene, E-ISSN 2325-1026, Vol. 4, artikel-id 000140Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Polynyas, or recurring areas of seasonally open water surrounded by sea ice, are foci for energy and material transfer between the atmosphere and the polar ocean. They are also climate sensitive, with both sea ice extent and glacial melt influencing their productivity. The Amundsen Sea Polynya (ASP) is the greenest polynya in the Southern Ocean, with summertime chlorophyll a concentrations exceeding 20 mu g L-1. During the Amundsen Sea Polynya International Research Expedition (ASPIRE) in austral summer 2010-11, we aimed to determine the fate of this high algal productivity. We collected water column profiles for total dissolved inorganic carbon (DIC) and nutrients, particulate and dissolved organic matter, chlorophyll a, mesozoo-plankton, and microbial biomass to make a carbon budget for this ecosystem. We also measured primary and secondary production, community respiration rates, vertical particle flux and fecal pellet production and grazing. With observations arranged along a gradient of increasing integrated dissolved inorganic nitrogen drawdown (Delta DIN; 0.027-0.74 mol N m(-2)), changes in DIC in the upper water column (ranging from 0.2 to 4.7 mol C m(-2)) and gas exchange (0-1.7 mol C m(-2)) were combined to estimate early season net community production (sNCP; 0.2-5.9 mol C m(-2)) and then compared to organic matter inventories to estimate export. From a phytoplankton bloom dominated by Phaeocystis antarctica, a high fraction (up to similar to 60%) of sNCP was exported to sub-euphotic depths. Microbial respiration remineralized much of this export in the mid waters. Comparisons to short-term (2-3 days) drifting traps and a year-long moored sediment trap capturing the downward flux confirmed that a relatively high fraction (3-6%) of the export from similar to 100 m made it through the mid waters to depth. We discuss the climate-sensitive nature of these carbon fluxes, in light of the changing sea ice cover and melting ice sheets in the region.

  • 624.
    Yildirim, Yeserin
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). Massey Univ, New Zealand.
    Anderson, Marti J.
    Massey Univ, New Zealand.
    Hansson, Bengt
    Lund University.
    Patel, Selina
    Univ Auckland, New Zealand.
    Millar, Craig D.
    Univ Auckland, New Zealand.
    Rainey, Paul B.
    Massey Univ, New Zealand;Max Planck Inst Evolutionary Biol, Germany;PSL Res Univ, France.
    Genetic structure of the grey side-gilled sea slug (Pleurobranchaea maculata) in coastal waters of New Zealand2018Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 13, nr 8, artikel-id e0202197Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Pleurobranchaea maculata is a rarely studied species of the Heterobranchia found throughout the south and western Pacific-and recently recorded in Argentina-whose population genetic structure is unknown. Interest in the species was sparked in New Zealand following a series of dog deaths caused by ingestions of slugs containing high levels of the neurotoxin tetrodotoxin. Here we describe the genetic structure and demographic history of P. maculata populations from five principle locations in New Zealand based on extensive analyses of 12 microsatellite loci and the COI and CytB regions of mitochondrial DNA (mtDNA). Microsatellite data showed significant differentiation between northern and southern populations with population structure being associated with previously described regional variations in tetrodotoxin concentrations. However, mtDNA sequence data did not support such structure, revealing a star-shaped haplotype network with estimates of expansion time suggesting a population expansion in the Pleistocene era. Inclusion of publicly available mtDNA sequence sea slugs from Argentina did not alter the star-shaped network. We interpret our data as indicative of a single founding population that fragmented following geographical changes that brought about the present day north-south divide in New Zealand waters. Lack of evidence of cryptic species supports data indicating that differences in toxicity of individuals among regions are a consequence of differences in diet.

  • 625.
    Zehr, Jonathan P.
    et al.
    University of California, USA.
    Shilova, Irina N.
    University of California, USA.
    Farnelid, Hanna
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). University of California, USA.
    Muñoz-Marín, Maria del Carmen
    University of California, USA;University of Córdoba, Spain.
    Turk-Kubo, Kendra A.
    University of California, USA.
    Unusual marine unicellular symbiosis with the nitrogen-fixing cyanobacterium UCYN-A2017Ingår i: Nature Microbiology, E-ISSN 2058-5276, Vol. 2, nr 1, s. 1-10, artikel-id 16214Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nitrogen fixation — the reduction of dinitrogen (N2) gas to biologically available nitrogen (N) — is an important source of N for terrestrial and aquatic ecosystems. In terrestrial environments, N2-fixing symbioses involve multicellular plants, but in the marine environment these symbioses occur with unicellular planktonic algae. An unusual symbiosis between an uncultivated unicellular cyanobacterium (UCYN-A) and a haptophyte picoplankton alga was recently discovered in oligotrophic oceans. UCYN-A has a highly reduced genome, and exchanges fixed N for fixed carbon with its host. This symbiosis bears some resemblance to symbioses found in freshwater ecosystems. UCYN-A shares many core genes with the ‘spheroid bodies’ of Epithemia turgida and the endosymbionts of the amoeba Paulinella chromatophora. UCYN-A is widely distributed, and has diversified into a number of sublineages that could be ecotypes. Many questions remain regarding the physical and genetic mechanisms of the association, but UCYN-A is an intriguing model for contemplating the evolution of N2-fixing organelles.

  • 626.
    Zhang, Hao
    et al.
    Chinese Univ Hong Kong, Peoples Republic of China.
    Yoshizawa, Susumu
    Univ Tokyo, Japan.
    Sun, Ying
    Chinese Univ Hong Kong, Peoples Republic of China.
    Huang, Yongjie
    Chinese Univ Hong Kong, Peoples Republic of China.
    Chu, Xiao
    Chinese Univ Hong Kong, Peoples Republic of China.
    Gonzalez, Jose M.
    Univ La Laguna, Spain.
    Pinhassi, Jarone
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Luo, Haiwei
    Chinese Univ Hong Kong, Peoples Republic of China.
    Repeated evolutionary transitions of flavobacteria from marine to non-marine habitats2019Ingår i: Environmental Microbiology, ISSN 1462-2912, E-ISSN 1462-2920, Vol. 21, nr 2, s. 648-666Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The taxonomy of marine and non-marine organisms rarely overlap, but the mechanisms underlying this distinction are often unknown. Here, we predicted three major ocean-to-land transitions in the evolutionary history of Flavobacteriaceae, a family known for polysaccharide and peptide degradation. These unidirectional transitions were associated with repeated losses of marine signature genes and repeated gains of non-marine adaptive genes. This included various Na+-dependent transporters, osmolyte transporters and glycoside hydrolases (GH) for sulfated polysaccharide utilization in marine descendants, and in non-marine descendants genes for utilizing the land plant material pectin and genes facilitating terrestrial host interactions. The K+ scavenging ATPase was repeatedly gained whereas the corresponding low-affinity transporter repeatedly lost upon transitions, reflecting K+ ions are less available to non-marine bacteria. Strikingly, the central metabolism Na+-translocating NADH: quinone dehydrogenase gene was repeatedly gained in marine descendants, whereas the H+-translocating counterpart was repeatedly gained in non-marine lineages. Furthermore, GH genes were depleted in isolates colonizing animal hosts but abundant in bacteria inhabiting other non-marine niches; thus relative abundances of GH versus peptidase genes among Flavobacteriaceae lineages were inconsistent with the marine versus non-marine dichotomy. We suggest that phylogenomic analyses can cast novel light on mechanisms explaining the distribution and ecology of key microbiome components.

  • 627.
    Zhao, Tao
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för kemi och biomedicin (KOB). KTH Royal Instute of Technology, Sweden;Örebro University, Sweden.
    Ganji, Suresh
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för kemi och biomedicin (KOB).
    Bohman, Björn
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för kemi och biomedicin (KOB). University of Western Australia, Australia.
    Weinstein, Philip
    University of Adelaide, Australia.
    Krokene, Paal
    Norwegian Institute of Bioeconomy Research, Norway.
    Borg-Karlsson, Anna-Karin
    KTH Royal Instute of Technology, Sweden.
    Unelius, C. Rikard
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för kemi och biomedicin (KOB).
    Convergent evolution of semiochemicals across Kingdoms: bark beetles and their fungal symbionts2019Ingår i: The ISME Journal, ISSN 1751-7362, E-ISSN 1751-7370, Vol. 13, nr 6, s. 1535-1545Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Convergent evolution of semiochemical use in organisms from different Kingdoms is a rarely described phenomenon. Treekilling bark beetles vector numerous symbiotic blue-stain fungi that help the beetles colonize healthy trees. Here we show for the first time that some of these fungi are able to biosynthesize bicyclic ketals that are pheromones and other semiochemicals of bark beetles. Volatile emissions of five common bark beetle symbionts were investigated by gas chromatography-mass spectrometry. When grown on fresh Norway spruce bark the fungi emitted three well-known bark beetle aggregation pheromones and semiochemicals (exo-brevicomin, endo-brevicomin and trans-conophthorin) and two structurally related semiochemical candidates (exo-1,3-dimethyl-2,9-dioxabicyclo[3.3.1]nonane and endo-1,3-dimethyl-2,9-dioxabicyclo[3.3.1] nonane) that elicited electroantennogram responses in the spruce bark beetle Ips typographus. When grown on malt agar with 13C D-Glucose, the fungus Grosmannia europhioides incorporated 13C into exo-brevicomin and trans-conophthorin. The enantiomeric compositions of the fungus-produced ketals closely matched those previously reported from bark beetles. The production of structurally complex bark beetle pheromones by symbiotic fungi indicates cross-kingdom convergent evolution of signal use in this system. This signaling is susceptible to disruption, providing potential new targets for pest control in conifer forests and plantations.

  • 628.
    Zhao, Yan
    et al.
    Chinese Acad Sci, Peoples Republic of China.
    Tang, Yu
    Lanzhou Univ, Peoples Republic of China.
    Yu, Zicheng
    Lehigh Univ, USA.
    Li, Huan
    Lanzhou Univ, Peoples Republic of China.
    Yang, Bao
    Chinese Acad Sci, Peoples Republic of China.
    Zhao, Wenwei
    Lanzhou Univ, Peoples Republic of China;Univ Cologne, Germany.
    Li, Furong
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). Lanzhou Univ, Peoples Republic of China.
    Li, Quan
    Chinese Acad Sci, Peoples Republic of China.
    Holocene peatland initiation, lateral expansion, and carbon dynamics in the Zoige Basin of the eastern Tibetan Plateau2014Ingår i: The Holocene, ISSN 0959-6836, E-ISSN 1477-0911, Vol. 24, nr 9, s. 1137-1145Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Zoige Basin on the eastern Tibetan Plateau has the largest area of highland peatlands in China. However, the development history of these peatlands is still poorly understood. Understanding how these carbon-rich ecosystems responded to change in the Asian summer monsoons during the Holocene will provide insight into the peatland carbon accumulation processes under different climate boundary conditions. Here, we document the timing of initiation and expansion histories of these peatlands using 59 new basal peat ages across the Zoige Basin, with 29 ages for initiation analysis and 30 additional ages for lateral expansion analysis. Also, we synthesized basal ages from 26 sites and carbon accumulation records at four sites from previous studies in this region. The results show that the peatland initiation is widespread at 11.5-10 and 7-6 kyr (1 kyr = 1000 cal. yr BP) and the minimum initiation periods occurred after 5 kyr. Our multiple basal ages along eight transects show that slopes are a dominant control on peatland lateral expansion rates, with very slow and less variable rates at slopes >0.4 degrees. Furthermore, we found a significant relationship between peatland basal ages and peat depths from 85 sites, suggesting relatively uniform peat properties. Carbon accumulation rates from detailed downcore analysis at four sites and on the basis of peat depth-basal age relationship show similar patterns with a peak carbon accumulation at 10-8 kyr. On the basis of estimated mean values of bulk density and carbon content from the region, the Holocene average C accumulation for the Zoige Basin is 31.1 g C/m(2)/yr. The widespread peatland initiation and rapid accumulation in the early Holocene were likely in response to higher temperature and stronger summer monsoon intensity, while the slowdown of peatland development during the late Holocene might have been caused by climate cooling and drying.

  • 629.
    Zverev, Vitali
    et al.
    University of Turku, Finland.
    Kozlov, Mikhail
    University of Turku, Finland.
    Forsman, Anders
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Zvereva, Elena
    University fo Turku, Finland.
    Ambient temperatures differently influence colour morphs of the leaf beetle Chrysomela lapponica: roles of thermal melanism and developmental plasticity2018Ingår i: Journal of Thermal Biology, ISSN 0306-4565, E-ISSN 1879-0992, Vol. 74, s. 100-109Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We asked whether ambient temperatures can affect morph frequencies within a subarctic population of thepolymorphic leaf beetle Chrysomela lapponica through thermal melanism and/or developmental plasticity. Bodytemperature increased faster in beetles of dark morph than in beetles of light morph under exposure to artificialirradiation. Dark males ran faster than light males in both field and laboratory experiments, and this differencedecreased with increasing ambient air temperature, from significant at 10 °C to non-significant at 20 °C and26 °C. On cold days (6–14 °C), significantly more dark males than light males were found on their host plants incopula (40.8% and 27.3% respectively); on warm days (15–22 °C) this difference disappeared. Light femalesproduced twice as many eggs as dark females; this difference did not depend on the ambient temperature. Theproportion of dark morphs in the progenies of pairs with one dark parent was twice as high as that in theprogenies of pairs in which both parents were light, and this proportion was greater when larvae developed atlow (10 and 15 °C) than at high (20 and 25 °C) temperatures. We conclude that low temperatures may increasethe frequencies of dark morphs in C. lapponica populations due to both the mating advantages of dark males overlight males and developmental plasticity. Variation in frequencies of low-fecund dark morphs in the population,caused by among-year differences in temperature together with density-dependent selection, may contribute tothe evolutionary dynamics of the colour polymorphism and may influence abundance fluctuations in these leafbeetle populations.

  • 630.
    Zvereva, Elena L.
    et al.
    Univ Turku, Finland.
    Castagneyrol, Bastien
    Univ Bordeaux, France.
    Cornelissen, Tatiana
    Univ Fed Minas Gerais, Brazil.
    Forsman, Anders
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Hernandez-Agueero, Juan Antonio
    Univ Rey Juan Carlos, Spain.
    Klemola, Tero
    Univ Turku, Finland.
    Paolucci, Lucas
    Univ Fed Lavras, Brazil;Inst Pesquisa Ambiental Amazonia, Brazil.;Univ Fed Vicosa, Brazil.
    Polo, Vicente
    Univ Rey Juan Carlos, Spain.
    Salinas, Norma
    Pontificia Univ Catolica Peru, Peru.
    Theron, Kasselman Jurie
    Stellenbosch Univ, South Africa.
    Xu, Guorui
    Chinese Acad Sci, China.
    Zverev, Vitali
    Univ Turku, Finland.
    Kozlov, Mikhail V.
    Univ Turku, Finland.
    Opposite latitudinal patterns for bird and arthropod predation revealed in experiments with differently colored artificial prey2019Ingår i: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 9, nr 24, s. 14273-14285Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The strength of biotic interactions is generally thought to increase toward the equator, but support for this hypothesis is contradictory. We explored whether predator attacks on artificial prey of eight different colors vary among climates and whether this variation affects the detection of latitudinal patterns in predation. Bird attack rates negatively correlated with model luminance in cold and temperate environments, but not in tropical environments. Bird predation on black and on white (extremes in luminance) models demonstrated different latitudinal patterns, presumably due to differences in prey conspicuousness between habitats with different light regimes. When attacks on models of all colors were combined, arthropod predation decreased, whereas bird predation increased with increasing latitude. We conclude that selection for prey coloration may vary geographically and according to predator identity, and that the importance of different predators may show contrasting patterns, thus weakening the overall latitudinal trend in top-down control of herbivorous insects.

  • 631.
    Zöttl, Markus
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). Univ Cambridge, UK.
    Vullioud, Philippe
    Univ Cambridge, UK.
    Goddard, Katy
    Kuruman River Reserve, South Africa.
    Torrents-Tico, Miquel
    Kuruman River Reserve, South Africa;Univ Helsinki, Finland.
    Gaynor, David
    Univ Pretoria, South Africa.
    Bennett, Nigel C.
    Univ Pretoria, South Africa.
    Clutton-Brock, Tim
    Univ Cambridge, UK;Univ Pretoria, South Africa.
    Allo-parental care in Damaraland mole-rats is female biased and age dependent, though independent of testosterone levels2018Ingår i: Physiology and Behavior, ISSN 0031-9384, E-ISSN 1873-507X, Vol. 193, s. 149-153Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In Damaraland mole-rats (Fukomys damal-ensis), non-breeding subordinates contribute to the care of offspring born to the breeding pair in their group by carrying and retrieving young to the nest. In social mole-rats and some cooperative breeders, dominant females show unusually high testosterone levels and it has been suggested that high testosterone levels may increase reproductive and aggressive behavior and reduce investment in allo-parental and parental care, generating age and state-dependent variation in behavior. Here we show that, in Damaraland mole-rats, allo-parental care in males and females is unaffected by experimental increases in testosterone levels. Pup carrying decreases with age of the non-breeding helper while the change in social status from non-breeder to breeder has contrasting effects in the two sexes. Female breeders were more likely than female non-breeders to carry pups but male breeders were less likely to carry pups than male non-breeders, increasing the sex bias in parental care compared to allo-parental care. Our results indicate that testosterone is unlikely to be an important regulator of allo-parental care in mole-rats.

  • 632.
    Ålkärr, Linus
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Studies on skin microbiota and growth of Northern pike (Esox lucius) larvae from a translocation experiment in two Swedish wetlands2017Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Yngel av gädda (Esox lucius) från ett translokeringsexperiment utfört i två svenska våtmarker i anslutning till Lerviksbäcken och Oknebäcken användes för att studera slemhinneassocierade bakteriesamhällen på hud och tillväxt hos fiskar från reproduktivt isolerade populationer av anadroma Östersjögäddor. Studier av mikrobiella samhällen gjordes genom att amplifiera och sekvensera gener för 16s rRNA i DNA-extrakt från slemprover. Syftet med detta var att leta efter  tecken på divergens mellan populationer och familjer som kunde tyda på skillnader i mekanismer hos värden som reglerar bindning av mikrober till slemhinnor. Ordination och PERMANOVA, i kombination med analys av alfadiversitet och taxonomisk sammansättning i mikrobiella samhällen, visade att fiskassocierade samhällen var distinkta från och hade högre mångfald än de i fiskarnas omgivande vatten. De två studerade populationerna verkade dock inte skilja sig  med avseende på mikrobiom. En möjlig effekt av genetiskt avstånd mellan individer upptäcktes, men eventuell kontaminering mellan prover kunde ej uteslutas som alternativ förklaring. Längdmätningar på yngel pekade på att populationerna ej skiljer sig åt i kroppslängd slutet av gulesäckstadiet, men att individer uppväxta i Oknebäck var längre än de uppväxta i Lerviksbäcken.

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