1,721,013 research outputs found
Havstulpanprojektet på västkusten 2012 : En studie om påväxtdynamik i norra Bohuslän under båtsäsongen 2012
No full textEtt vanligt sätt att motverka problem med påväxt på båtar är att måla med båtbottenfärger. Men det finns många miljörelaterade problem med användandet av dessa färger och trots omfattande forskning under de senaste åren finns inget effektivt och helt miljövänligt färgalternativ på marknaden idag. Alternativa metoder omfattar mekanisk rengöring, exempelvis med hjälp av högtryckstvätt på spolplatta, eller landförvaring. Sedan år 2001 har Skärgårdsstiftelsen i Stockholm drivit ett projekt som syftar till att minska användandet av giftiga båtbottenfärger genom ett övervakningsprogram med information till allmänheten om när det har satt sig havstulpaner och det är dags att tvätta båten. Längs stora delar av Östersjökusten, där påväxten av havstulpaner är begränsad till ett fåtal tillfällen under båtsäsongen, har detta fungerat relativt bra. På västkusten däremot, är påväxtdynamiken generellt mer komplex, med fler påväxtarter och tätare larvsettlingsperioder under båtsäsongen. Dock finns få studier som kvantitativt har undersökt påväxten längs västkusten samt hur detta varierar under en hel båtsäsong. Syftet med denna studie var därför att i fält dokumentera påväxtdynamiken längs den svenska västkusten under båtsäsongen 2012 samt utvärdera potentialen för att använda mekanisk rengöring av båtar i större utsträckning längs västkusten. Som förväntat, observerades högre artrikedom av påväxt längs västkusten jämfört med vad som normalt förekommer längs ostkusten. Påväxten dominerades av havstulpaner, sjöpungar och musslor, men även mossdjur, hydroider och fintrådiga alger etablerade sig på panelerna. Stor variation i artsammansättning och intensitet av påväxt observerades mellan olika närliggande lokaler, men främst på paneler som hängt i fält i minst fyra veckor. Nysettlade havstulpaner observerades vid varje undersökningstillfälle (d.v.s. varannan vecka) under hela båtsäsongen (dock främst i juni-augusti) vilket indikerar kontinuerlig rekrytering under hela perioden. Påväxten på panelerna överensstämde relativt väl med båtskroven, särskilt under den första tiden efter utplacering i havet. Utifrån resultaten i denna studie skulle rengöring av båtskrov i norra Bohuslän behövas varannan till var fjärde vecka för att hålla svårhanterlig påväxt borta och underlätta rengöring med enklare mekaniska metoder. Projektet var ett samarbete mellan Skärgårdsstiftelsen i Stockholms län och Göteborgs Universitet, med finansiering genom Hav- och vattenmyndigheten.Since 2001, Skärgårdsstiftelsen in Stockholm has been running a monitoring project along the Swedish east coast on barnacle fouling on boats with the aim to reduce the use of toxic antifouling paints, and promote more environmentally friendly methods such as mechanical cleaning. The project involves making observations of barnacle settlement available to the public, so that boats can be taken out of the water in time and cleaned before the barnacles attach too firmly. This system has worked well along parts of the Baltic Sea coast, since barnacles only settle a few times per year. However, on the Swedish west coast the fouling community is generally more complex with higher species diversity and more intense fouling throughout the season. The aim of this study was to document the intensity and dynamics of the fouling community on the Swedish west coast and evaluate the potential for increased use of mechanical cleaning of boat hauls, as an alternative to using antifouling paints. As expected the species diversity and intensity was considerably higher than what is normally observed along the Baltic Sea coast. The fouling community was dominated by barnacles, tunicates and mussels, but also bryozoans, hydroids and filamentous algae were observed. Species composition and intensity of fouling differed considerably between closely located sites, especially after four weeks. Barnacles dominated the community at all sites during the first two weeks after panels had been placed in the sea. Newly settled barnacles were observed throughout the whole boat season, although intensities were highest in June-August. The fouling on the panels corresponded relatively well with what was observed on boat hauls, especially during the first weeks. Based on these results, mechanical cleaning of boat hauls is recommended every two to four weeks, to avoid difficulties in removing fouling organisms using simple mechanical techniques. This project was a collaboration between Skärgårdsstiftelsen in Stockholm and the University of Gothenburg, with funding from the Swedish Agency for Marine and Water Management
From geography to genes: evolutionary perspectives on salinity tolerance in the brackish water barnacle Balanus improvisus
No full textHow species respond to changes in their environment is a fundamental question in biology. This has become an increasingly important issue as anthropogenic effects of climate change and biological invasions have major impacts on marine ecosystems worldwide. In this thesis I investigated the role of salinity tolerance from an evolutionary perspective, using a wide range of techniques, spanning from population genetics and common-garden experiments to characterizing potential genes involved in osmoregulation in barnacles. I used the acorn barnacle species Balanus (Amphibalanus) improvisus, which displays a remarkably broad salinity tolerance, to investigate how this trait has influenced the species' potential to establish in new environments, and respond to projected near-future salinity reductions in coastal seas. I also examined physiological and molecular mechanisms that may be involved in osmoregulation in B. improvisus. I further analysed population genetic structure using microsatellites and mitochondrial DNA, and related the results to anthropogenic and natural dispersal dynamics on both global and regional (Baltic Sea) scales. I found high genetic diversity in most populations, with many shared haplotypes between distant populations. This supports the hypothesis that maritime shipping is an important vector for the dispersal of the cosmopolitan species B. improvisus. Nonetheless, natural larval dispersal is also important on smaller geographical scales, such as within the Baltic Sea. Marked genetic differentiation between northern and southern Baltic Sea populations raises the question whether there is restricted gene flow within the Baltic Sea, creating potential for local adaptations to evolve. To investigate the extent to which the broad distribution of B. improvisus along the Baltic Sea salinity gradient is explained by local adaptation versus physiological plasticity, I performed a common-garden experiment in which multiple populations were exposed to different salinities and multiple fitness-related phenotypic traits were recorded. The experiment confirmed that phenotypic plasticity, rather than local adaptation, explained the broad distribution of the species along the salinity gradient. Interestingly, all populations of B. improvisus performed best at low and intermediate salinities in many fitness-related traits (survival, growth and reproduction), although other traits (e.g. shell strength an juvenile growth) indicated higher costs associated with low salinity. A candidate gene approach was used to investigate the molecular basis of broad salinity tolerance in B. improvisus by characterizing the Na+/K+ ATPase (NAK) of B. improvisus – an ion transporter commonly involved in active osmoregulation in many species. We identified two main gene variants in B. improvisus (NAK1 and NAK2), and found that NAK1 mRNA existed in two isoforms that were differentially expressed in different life stages and adult tissues, suggesting an active role in osmoregulation. Lastly, I summarise current knowledge about salinity tolerance in barnacles and outline new research directions to further our understanding of the physiological and molecular mechanisms involved in salinity tolerance in barnacles
Havstulpanprojektet på västkusten 2012 [Elektronisk resurs] : En studie om påväxtdynamik i norra Bohuslän under båtsäsongen 2012
No full textEtt vanligt sätt att motverka problem med påväxt på båtar är att måla med båtbottenfärger. Men det finns många miljörelaterade problem med användandet av dessa färger och trots omfattande forskning under de senaste åren finns inget effektivt och helt miljövänligt färgalternativ på marknaden idag. Alternativa metoder omfattar mekanisk rengöring, exempelvis med hjälp av högtryckstvätt på spolplatta, eller landförvaring. Sedan år 2001 har Skärgårdsstiftelsen i Stockholm drivit ett projekt som syftar till att minska användandet av giftiga båtbottenfärger genom ett övervakningsprogram med information till allmänheten om när det har satt sig havstulpaner och det är dags att tvätta båten. Längs stora delar av Östersjökusten, där påväxten av havstulpaner är begränsad till ett fåtal tillfällen under båtsäsongen, har detta fungerat relativt bra. På västkusten däremot, är påväxtdynamiken generellt mer komplex, med fler påväxtarter och tätare larvsettlingsperioder under båtsäsongen. Dock finns få studier som kvantitativt har undersökt påväxten längs västkusten samt hur detta varierar under en hel båtsäsong. Syftet med denna studie var därför att i fält dokumentera påväxtdynamiken längs den svenska västkusten under båtsäsongen 2012 samt utvärdera potentialen för att använda mekanisk rengöring av båtar i större utsträckning längs västkusten. Som förväntat, observerades högre artrikedom av påväxt längs västkusten jämfört med vad som normalt förekommer längs ostkusten. Påväxten dominerades av havstulpaner, sjöpungar och musslor, men även mossdjur, hydroider och fintrådiga alger etablerade sig på panelerna. Stor variation i artsammansättning och intensitet av påväxt observerades mellan olika närliggande lokaler, men främst på paneler som hängt i fält i minst fyra veckor. Nysettlade havstulpaner observerades vid varje undersökningstillfälle (d.v.s. varannan vecka) under hela båtsäsongen (dock främst i juni-augusti) vilket indikerar kontinuerlig rekrytering under hela perioden. Påväxten på panelerna överensstämde relativt väl med båtskroven, särskilt under den första tiden efter utplacering i havet. Utifrån resultaten i denna studie skulle rengöring av båtskrov i norra Bohuslän behövas varannan till var fjärde vecka för att hålla svårhanterlig påväxt borta och underlätta rengöring med enklare mekaniska metoder. Projektet var ett samarbete mellan Skärgårdsstiftelsen i Stockholms län och Göteborgs Universitet, med finansiering genom Hav- och vattenmyndigheten.Since 2001, Skärgårdsstiftelsen in Stockholm has been running a monitoring project along the Swedish east coast on barnacle fouling on boats with the aim to reduce the use of toxic antifouling paints, and promote more environmentally friendly methods such as mechanical cleaning. The project involves making observations of barnacle settlement available to the public, so that boats can be taken out of the water in time and cleaned before the barnacles attach too firmly. This system has worked well along parts of the Baltic Sea coast, since barnacles only settle a few times per year. However, on the Swedish west coast the fouling community is generally more complex with higher species diversity and more intense fouling throughout the season. The aim of this study was to document the intensity and dynamics of the fouling community on the Swedish west coast and evaluate the potential for increased use of mechanical cleaning of boat hauls, as an alternative to using antifouling paints. As expected the species diversity and intensity was considerably higher than what is normally observed along the Baltic Sea coast. The fouling community was dominated by barnacles, tunicates and mussels, but also bryozoans, hydroids and filamentous algae were observed. Species composition and intensity of fouling differed considerably between closely located sites, especially after four weeks. Barnacles dominated the community at all sites during the first two weeks after panels had been placed in the sea. Newly settled barnacles were observed throughout the whole boat season, although intensities were highest in June-August. The fouling on the panels corresponded relatively well with what was observed on boat hauls, especially during the first weeks. Based on these results, mechanical cleaning of boat hauls is recommended every two to four weeks, to avoid difficulties in removing fouling organisms using simple mechanical techniques. This project was a collaboration between Skärgårdsstiftelsen in Stockholm and the University of Gothenburg, with funding from the Swedish Agency for Marine and Water Management.</p
Japanskt jätteostron invaderar svenska västkusten
No full textSommaren 2007 upptäcktes en ny ostronart vid den svenska västkusten. På flera platser som tidigare varit musselbankar finns nu istället flera hundra ostron per kvadratmeter. Det är japanskt jätteostron Crassostrea gigas som har dykt upp, en art som klassas som en av de mest invasionsbenägna arterna i hela världen och som har ställt till med problem i marina miljöer på många håll. Exakt vilka effekter ostronen kommer att ha i svenska vatten är för tidigt att säga, men det är tydligt att dessa delikatesser är här för att stanna
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Panel comparison observed in marinas in the north-eastern Baltic Sea
No full textIn the present study, we collected data on biofouling in 17 marinas along the Baltic Sea coast during three consecutive boating seasons (May-October 2014, 2015 and 2016). In this context, we compared different monitoring strategies and developed a fouling index (FI) to characterise marinas according to the recorded biofouling abundance and type (defined according to the hardness and strength of attachment to the substrate). Lower FI values, i.e. softer and/or less abundant biofouling, were consistently observed in marinas in the north-eastern Baltic Sea. The decrease in FI from the south-western to the north-eastern Baltic Sea was partially explained by the concomitant decrease in salinity. Nevertheless, most of the observed changes in biofouling seemed to be determined by local factors and inter-annual variability, which emphasizes the necessity for systematic monitoring of biofouling by end-users and/or authorities for the effective implementation of non-toxic antifouling alternatives in marinas
Biofouling abundance and type observed in marinas in the north-eastern Baltic Sea
No full textIn the present study, we collected data on biofouling in 17 marinas along the Baltic Sea coast during three consecutive boating seasons (May-October 2014, 2015 and 2016). In this context, we compared different monitoring strategies and developed a fouling index (FI) to characterise marinas according to the recorded biofouling abundance and type (defined according to the hardness and strength of attachment to the substrate). Lower FI values, i.e. softer and/or less abundant biofouling, were consistently observed in marinas in the north-eastern Baltic Sea. The decrease in FI from the south-western to the north-eastern Baltic Sea was partially explained by the concomitant decrease in salinity. Nevertheless, most of the observed changes in biofouling seemed to be determined by local factors and inter-annual variability, which emphasizes the necessity for systematic monitoring of biofouling by end-users and/or authorities for the effective implementation of non-toxic antifouling alternatives in marinas
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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