Contemporary divergence in early life history in grayling (Thymallus thymallus)

<p>Abstract</p> <p>Background</p> <p>Following colonization of new habitats and subsequent selection, adaptation to environmental conditions might be expected to be rapid. In a mountain lake in Norway, Lesjaskogsvatnet, more than 20 distinct spawning demes of grayling have been established since the lake was colonized, some 20-25 generations ago. The demes spawn in tributaries consistently exhibiting either colder or warmer temperature conditions during spawning in spring and subsequent early development during early summer. In order to explore the degree of temperature-related divergence in early development, a multi-temperature common-garden experiment was performed on embryos from four different demes experiencing different spring temperatures.</p> <p>Results</p> <p>Early developmental characters were measured to test if individuals from the four demes respond differently to the treatment temperatures. There was clear evidence of among-deme differences (genotype - environment interactions) in larval growth and yolk-to-body-size conversion efficiency. Under the cold treatment regime, larval growth rates were highest for individuals belonging to cold streams. Individuals from warm streams had the highest yolk-consumption rate under cold conditions. As a consequence, yolk-to-body-mass conversion efficiency was highest for cold-deme individuals under cold conditions. As we observed response parallelism between individuals from demes belonging to similar thermal groups for these traits, some of the differentiation seems likely to result from local adaptation</p> <p>Conclusion</p> <p>The observed differences in length at age during early larval development most likely have a genetic component, even though both directional and random processes are likely to have influenced evolutionary change in the demes under study.</p

Population differences in early development in grayling (Thymallus thymallus) : a common garden experiment

Following colonization of new habitats and subsequent strong selection, adaptation to environmental conditions might be expected to be rapid. In a mountainous lake in Norway, Lesjaskogsvatnet, more than 20 distinct spawning demes of grayling have been established since the lake was colonized, less than 25 generations ago. The demes spawn in tributaries consistently exhibiting either cold or warm temperature conditions. I conducted a common garden experiment to investigate if differences in early developmental characters had been established between four demes in response to the different nursery environments the grayling embryos and larvae experience. Different subsets of individuals from the four demes were subjected to three different treatment temperatures to test for temperature effects. Traits related to timing of development (i.e. eye pigmentation and hatching) as well as growth and energy consumption (i.e. length and yolk sack size) were measured for individuals from daily samples from all demes in all temperatures. I found no differences in the timing of early developmental traits. However, traits related to larval growth and energy consumption showed significant variation. Such variation most likely reflects genetic differences; however the observed variation did not unambiguously correspond with predictions of countergradient variation or local adaptation. I conclude that the observed differences in growth related traits between demes are most probably a result of both directional and random processes influencing evolutionary change

Sorption, biodegradation and leaching of diuron, hexazinone and sulfometuron-methyl alone and in mixture and effects on soil microrganism

Durante a safra agrícola ocorrem aplicações simultâneas ou aplicações de um defensivo agrícola em seguida de outro. Esta prática gera a combinação de resíduos no solo que pode levar a mudanças no destino final destes compostos. Com o objetivo de investigar se a aplicação em mistura influencia no comportamento no solo de diuron, hexazinone e sulfometuron-methyl foram avaliadas a sorção, dessorção, biodegradação, lixiviação e efeito sobre microrganismos dos solos, após aplicação em mistura e isolada destes herbicidas, em diferentes solos. Nos estudos de lixiviação, sorção e biodegradação foram preparadas soluções com herbicidas radiomarcados e não radiomarcados. Nos tratamentos em mistura apenas o herbicida sendo avaliado era radiomarcado e os outros eram padrões analíticos. A avaliação do efeito sobre microrganismos foi realizada após aplicação dos herbicidas e de glicose radiomarcada. O delineamento utilizado foi o inteiramente casualizado. A mineralização e a porcentagem detectada nos lixiviados do solo arenoso, foram maiores quando hexazinone foi aplicado em mistura. A sorção foi menor quando hexazinone estava em mistura com diuron, em um dos cinco solos avaliados. A mineralização e sorção de diuron nos solos não foram influenciadas pela presença de hexazinone e sulfometuron-methyl. No caso de sulfometuron-methyl, a aplicação em mistura aumentou a mineralização do herbicida, contudo, não afetou a lixiviação tampouco a sorção do herbicida. Maior evolução de 14CO2 a partir da glicose foi observada nos tratamentos com sulfometuron-methyl, diuron e da mistura dos três herbicidas em solo arenoso, contudo não foi observado aumento dos efeitos dos herbicidas quando em mistura sobre atividade biológica do solo.Herbicides can either be applied alone or simultaneously during the entire crop cultivation. This practice could potentially promote changes in herbicide behavior in the soil. Thus, the aim of this study was to understand the effect of diuron, hexazinone, and sulfometuron-methyl and its mixtures when applied on the soil. Herbicide sorption, desorption, biodegradation, leaching and its effect on the soil microorganism in contrasting soils textures were evaluated. Radiolabeled and an analytical standard herbicide were used to understand leaching, biodegradation and sorption. Microorganism evaluation was done by adding 14C-glucose. Highest mineralization percentage was observed in hexazinone mixed with diuron and sulfometuron-methyl leachates. The application in mixture did not affect the mineralization or sorption of diuron. In the case of sulfometuron-methyl, the application with diuron and hexazinone increased the mineralization of the herbicide, however it did not affect its leaching or sorption. A greater evolution of 14CO2 was observed in the treatments with sulfometuron-methyl, diuron and the mixture of the three herbicides in sand soil. Nevertheless, the application in mixture did not increase the effects of the herbicides in the soil biological activity

Restoration potential of old dams in Norway. A pilot study of occurrence, characteristics and restoration po-tential in watercourses with anadromous and resident fish stocks.

Eloranta, A., Thomassen, G., Bergan, M.A., Andersen, O. & Gregersen, F. 2019. Restoration potential of old dams in Norway. A pilot study of occurrence, characteristics and restoration potential in watercourses with anadromous and resident fish stocks. NINA Report 1628. Norwegian Institute for Nature Research. Man-made migration obstacles and barriers, such as dams and culverts, are among the main reasons why numerous migratory fish stocks (e.g. Atlantic salmon Salmo salar, sea trout Salmo trutta, and European eel Anguilla anguilla) in Norway and elsewhere have become locally endangered or extinct. This is particularly the case in small streams which are often neglected by management authorities, despite of their high importance for fish recruitment and water quality in downstream river, lake and coastal areas. To reach good ecological status in Norwegian freshwaters, river restorations and mapping of migration barriers are urgently needed to improve connectivity and ecological status of these valuable ecosystems. The main objectives of this pilot project were (1) to evaluate the number, location, characteristics and restoration potential of old dams that are no longer in use, and (2) to give an overview of relevant literature and projects related to barrier removals. Data on dams were collected with a publicly available, electronic questionnaire and by conducting field surveys in two types of watercourses: (1) inner and outer coastal areas of Trondheimsfjorden with anadromous fish (sea trout, salmon and/or eel) and (2) tributaries of Drammenselva with resident fish stocks (mainly brown trout, but also lamprey Lampetra sp., eel and freshwater pearl mussel Margaritifera mar-garitifera). Based on our results from 102 dams, only 21% of the reported dams are currently among the 3887 registered dams in the national DamPunkt-database (www.nve.no). Hence, the total number of dams in Norway can be roughly estimated to exceed 18 000. Most dams studied were made of concrete and/or stone and were typically 1–10 m high, 2–20 m wide, and partial or total migration barriers for aquatic biota. Most dams were currently used for hydropower operations, but some were originally built for other purposes. Our field surveys demonstrate that large areas of suitable fish spawning habitats are lost due to dams. In Trondheimsfjorden, numerous (mainly unregistered) dams are built for fish hatcheries that are no longer in operation and thus cause unnecessary fragmentation of anadromous river systems. Our two examples of potential restoration targets in Trondheimsfjorden (i.e., Kaldvella in Gaula river system and Dragvatnet in Hitra) demonstrate how barrier removal or restoration would substantially increase the accessible spawning and nursing habitats for anadromous fish. In Drammenselva area with long history of mining, forestry and hydropower activities, a great proportion of suitable spawning and nursing habitats for brown trout and freshwater pearl mussel is lost due to damming of small streams. Some dams have naturally collapsed and thus create only partial migration barriers for aquatic biota. However, the major and most difficult restoration targets are in the downstream river sections where even some very new dams block migratory fish. Various public institutions have collected information of man-made barriers in Norwegian watercourses. To support efficient and holistic planning and implementation of river restoration projects, these data should be gathered into a single, open-access database. Moreover, a user-friendly registration system (e.g. a mobile application) should be developed for mapping and reporting of old dams and other migration barriers (cf. “citizen-science project”). From an international perspective, Norway should become a more active member in present and future European river restoration projects (e.g. AMBER and Dam Removal Europe). This would help to increase public awareness and involvement, improve ecological status of riverine ecosystems and their valuable biota, and support fundamental applied science with wide international outreach.Eloranta, A., Thomassen, G., Bergan, M.A., Andersen, O. & Gregersen, F. 2019. Restaureringspotensial av gamle demninger i Norge. En pilotundersøkelse av forekomst, egenskaper og gjenopprettingspotensial i vassdrag med diadrome og stedegne fiskebestander. NINA Rapport 1628. Norsk institutt for naturforskning. Menneskeskapte vandringshindre er blant hovedårsakene til at vandrende fiskebestander (f.eks. laks Salmo salar, sjøørret Salmo trutta, og ål Anguilla anguilla) har blitt negativt påvirket eller utryddet i Norge. Dette gjelder spesielt i mindre elver, som er viktige for fiskeproduksjon, men ofte oversett av forvaltningsmyndighetene. I Norske vassdrag er restaurering og kartlegging av vandringshindre et viktig virkemiddel for å gjenopprette konnektivet og god økologisk status i disse mindre, men verdifulle økosystemene. Hovedformålet med dette pilotprosjektet er: (1) å kartlegge antall, plassering, karakteristika og restaureringspotensial for demninger som ikke lenger er i bruk, (2) å gi en oversikt over relevant litteratur og damprosjekter med tanke på å fjerne vandringshindre. Vi samlet data om demninger ved bruk av et åpent spørreskjema hvor folk kunne registrere demninger som ikke lenger var i bruk. Vi valgte også ut to områder for nærmere feltundersøkelser: (1) indre og ytre deler av Trondheimsfjorden med diadrome arter (f.eks. sjøørret, laks og/eller ål) og (2) Drammensvassdraget med sideelver med stedegne fiskebestander (i hovedsak ørret, men også elvemusling Margaritifera margaritifera, niøye Lampetra sp. og ål). Basert på spørreundersøkelsen og feltstudiene (n = 102 demninger), var bare 21% av de demningene vi har registrert blant de 3887 demningene som er registrert i DamPunkt-databasen til NVE. Dette betyr at det kan være totalt mer enn 18 000 demninger i Norge. Den gjennomsnittlige demningen i denne studien var bygd av betong eller stein og var typisk 1–10 m høy, 2–20 m bred og fungerte helt eller delvis som vandringsbarriere for fisk eller andre vannlevende organismer. De fleste av demningene er utnyttet for vannkraftformål, men flere hadde blitt bygd i forbindelse med annen aktivitet. Resultatene fra de to studieområdene viser tydelig at store bekke- og elvearealer egnet som gyteområder er utilgjengelige som følge av demninger i vassdragene. I Trondheimsfjordområdet er flere demninger som ikke lenger er i bruk (og som ikke finnes i NVE sin DamPunkt-database) bygget på grunn av fiskeoppdrett. Disse fører til en fragmentering av anadrom strekning og reduserer gyte- og oppvekstområder. To eksempler (Kaldvella i Gaula og Dragvatnet på Hitra) viser hvordan fjerning av demninger som ikke lenger er i bruk kan øke arealet av de tilgjengelige gyte- og oppvekstområder. I Drammenselvas nedbørsfelt er en stor andel av egnede gyte- og oppvekstområder for ørret og elveperlemusling gjort utilgjengelige på grunn av gruvedrift, tømmerfløting og vannkraft. Noen av demningene har i dag kollapset og utgjør et delvis vandringshinder for vannlevende organismer. De største vandringshindrene ligger i de nedre deler av tilløpselvene (f.eks. Dørja, Bingselva og Hoenselva), der demninger (noen nokså nye), hindrer vandring. Ulike institusjoner i Norge (f.eks. NVE, Statens vegvesen, Fylkesmannen, kommuner og forskningsinstitusjoner) har samlet informasjon om menneskeskapte vandringshindre i vassdrag over hele Norge. For å sikre effektiv og helhetlig planlegging og gjennomføring av elverestaurerings-prosjekter, bør slike data samles i en felles, åpen database. Videre bør det utvikles et brukervennlig registreringssystem (f.eks. en norsk mobilapp) for å tilrettelegge for en storskala kartlegging av vandringshindre i Norge (som “folkeforskningsprosjekt”). Norge burde bli mer aktiv i på-gående og fremtidige europeiske elverestaureringsprosjekter (som AMBER eller Dam Removal Europe). En slik strategi vil bidra til å øke folks bevissthet og involvering i restaureringsprosjekter, forbedre økologisk status i mange vassdrag med tanke på fisk og andre akvatiske organismer, og støtte grunnleggende anvendt forskning med bred, internasjonal rekkevidde

Restoration potential of old dams in Norway. A pilot study of occurrence, characteristics and restoration po-tential in watercourses with anadromous and resident fish stocks.

Eloranta, A., Thomassen, G., Bergan, M.A., Andersen, O. & Gregersen, F. 2019. Restoration potential of old dams in Norway. A pilot study of occurrence, characteristics and restoration potential in watercourses with anadromous and resident fish stocks. NINA Report 1628. Norwegian Institute for Nature Research. Man-made migration obstacles and barriers, such as dams and culverts, are among the main reasons why numerous migratory fish stocks (e.g. Atlantic salmon Salmo salar, sea trout Salmo trutta, and European eel Anguilla anguilla) in Norway and elsewhere have become locally endangered or extinct. This is particularly the case in small streams which are often neglected by management authorities, despite of their high importance for fish recruitment and water quality in downstream river, lake and coastal areas. To reach good ecological status in Norwegian freshwaters, river restorations and mapping of migration barriers are urgently needed to improve connectivity and ecological status of these valuable ecosystems. The main objectives of this pilot project were (1) to evaluate the number, location, characteristics and restoration potential of old dams that are no longer in use, and (2) to give an overview of relevant literature and projects related to barrier removals. Data on dams were collected with a publicly available, electronic questionnaire and by conducting field surveys in two types of watercourses: (1) inner and outer coastal areas of Trondheimsfjorden with anadromous fish (sea trout, salmon and/or eel) and (2) tributaries of Drammenselva with resident fish stocks (mainly brown trout, but also lamprey Lampetra sp., eel and freshwater pearl mussel Margaritifera mar-garitifera). Based on our results from 102 dams, only 21% of the reported dams are currently among the 3887 registered dams in the national DamPunkt-database (www.nve.no). Hence, the total number of dams in Norway can be roughly estimated to exceed 18 000. Most dams studied were made of concrete and/or stone and were typically 1–10 m high, 2–20 m wide, and partial or total migration barriers for aquatic biota. Most dams were currently used for hydropower operations, but some were originally built for other purposes. Our field surveys demonstrate that large areas of suitable fish spawning habitats are lost due to dams. In Trondheimsfjorden, numerous (mainly unregistered) dams are built for fish hatcheries that are no longer in operation and thus cause unnecessary fragmentation of anadromous river systems. Our two examples of potential restoration targets in Trondheimsfjorden (i.e., Kaldvella in Gaula river system and Dragvatnet in Hitra) demonstrate how barrier removal or restoration would substantially increase the accessible spawning and nursing habitats for anadromous fish. In Drammenselva area with long history of mining, forestry and hydropower activities, a great proportion of suitable spawning and nursing habitats for brown trout and freshwater pearl mussel is lost due to damming of small streams. Some dams have naturally collapsed and thus create only partial migration barriers for aquatic biota. However, the major and most difficult restoration targets are in the downstream river sections where even some very new dams block migratory fish. Various public institutions have collected information of man-made barriers in Norwegian watercourses. To support efficient and holistic planning and implementation of river restoration projects, these data should be gathered into a single, open-access database. Moreover, a user-friendly registration system (e.g. a mobile application) should be developed for mapping and reporting of old dams and other migration barriers (cf. “citizen-science project”). From an international perspective, Norway should become a more active member in present and future European river restoration projects (e.g. AMBER and Dam Removal Europe). This would help to increase public awareness and involvement, improve ecological status of riverine ecosystems and their valuable biota, and support fundamental applied science with wide international outreach

Restoration potential of old dams in Norway. A pilot study of occurrence, characteristics and restoration po-tential in watercourses with anadromous and resident fish stocks.

Eloranta, A., Thomassen, G., Bergan, M.A., Andersen, O. & Gregersen, F. 2019. Restoration potential of old dams in Norway. A pilot study of occurrence, characteristics and restoration potential in watercourses with anadromous and resident fish stocks. NINA Report 1628. Norwegian Institute for Nature Research. Man-made migration obstacles and barriers, such as dams and culverts, are among the main reasons why numerous migratory fish stocks (e.g. Atlantic salmon Salmo salar, sea trout Salmo trutta, and European eel Anguilla anguilla) in Norway and elsewhere have become locally endangered or extinct. This is particularly the case in small streams which are often neglected by management authorities, despite of their high importance for fish recruitment and water quality in downstream river, lake and coastal areas. To reach good ecological status in Norwegian freshwaters, river restorations and mapping of migration barriers are urgently needed to improve connectivity and ecological status of these valuable ecosystems. The main objectives of this pilot project were (1) to evaluate the number, location, characteristics and restoration potential of old dams that are no longer in use, and (2) to give an overview of relevant literature and projects related to barrier removals. Data on dams were collected with a publicly available, electronic questionnaire and by conducting field surveys in two types of watercourses: (1) inner and outer coastal areas of Trondheimsfjorden with anadromous fish (sea trout, salmon and/or eel) and (2) tributaries of Drammenselva with resident fish stocks (mainly brown trout, but also lamprey Lampetra sp., eel and freshwater pearl mussel Margaritifera mar-garitifera). Based on our results from 102 dams, only 21% of the reported dams are currently among the 3887 registered dams in the national DamPunkt-database (www.nve.no). Hence, the total number of dams in Norway can be roughly estimated to exceed 18 000. Most dams studied were made of concrete and/or stone and were typically 1–10 m high, 2–20 m wide, and partial or total migration barriers for aquatic biota. Most dams were currently used for hydropower operations, but some were originally built for other purposes. Our field surveys demonstrate that large areas of suitable fish spawning habitats are lost due to dams. In Trondheimsfjorden, numerous (mainly unregistered) dams are built for fish hatcheries that are no longer in operation and thus cause unnecessary fragmentation of anadromous river systems. Our two examples of potential restoration targets in Trondheimsfjorden (i.e., Kaldvella in Gaula river system and Dragvatnet in Hitra) demonstrate how barrier removal or restoration would substantially increase the accessible spawning and nursing habitats for anadromous fish. In Drammenselva area with long history of mining, forestry and hydropower activities, a great proportion of suitable spawning and nursing habitats for brown trout and freshwater pearl mussel is lost due to damming of small streams. Some dams have naturally collapsed and thus create only partial migration barriers for aquatic biota. However, the major and most difficult restoration targets are in the downstream river sections where even some very new dams block migratory fish. Various public institutions have collected information of man-made barriers in Norwegian watercourses. To support efficient and holistic planning and implementation of river restoration projects, these data should be gathered into a single, open-access database. Moreover, a user-friendly registration system (e.g. a mobile application) should be developed for mapping and reporting of old dams and other migration barriers (cf. “citizen-science project”). From an international perspective, Norway should become a more active member in present and future European river restoration projects (e.g. AMBER and Dam Removal Europe). This would help to increase public awareness and involvement, improve ecological status of riverine ecosystems and their valuable biota, and support fundamental applied science with wide international outreach

Restoration potential of old dams in Norway. A pilot study of occurrence, characteristics and restoration po-tential in watercourses with anadromous and resident fish stocks.

Eloranta, A., Thomassen, G., Bergan, M.A., Andersen, O. & Gregersen, F. 2019. Restoration potential of old dams in Norway. A pilot study of occurrence, characteristics and restoration potential in watercourses with anadromous and resident fish stocks. NINA Report 1628. Norwegian Institute for Nature Research. Man-made migration obstacles and barriers, such as dams and culverts, are among the main reasons why numerous migratory fish stocks (e.g. Atlantic salmon Salmo salar, sea trout Salmo trutta, and European eel Anguilla anguilla) in Norway and elsewhere have become locally endangered or extinct. This is particularly the case in small streams which are often neglected by management authorities, despite of their high importance for fish recruitment and water quality in downstream river, lake and coastal areas. To reach good ecological status in Norwegian freshwaters, river restorations and mapping of migration barriers are urgently needed to improve connectivity and ecological status of these valuable ecosystems. The main objectives of this pilot project were (1) to evaluate the number, location, characteristics and restoration potential of old dams that are no longer in use, and (2) to give an overview of relevant literature and projects related to barrier removals. Data on dams were collected with a publicly available, electronic questionnaire and by conducting field surveys in two types of watercourses: (1) inner and outer coastal areas of Trondheimsfjorden with anadromous fish (sea trout, salmon and/or eel) and (2) tributaries of Drammenselva with resident fish stocks (mainly brown trout, but also lamprey Lampetra sp., eel and freshwater pearl mussel Margaritifera mar-garitifera). Based on our results from 102 dams, only 21% of the reported dams are currently among the 3887 registered dams in the national DamPunkt-database (www.nve.no). Hence, the total number of dams in Norway can be roughly estimated to exceed 18 000. Most dams studied were made of concrete and/or stone and were typically 1–10 m high, 2–20 m wide, and partial or total migration barriers for aquatic biota. Most dams were currently used for hydropower operations, but some were originally built for other purposes. Our field surveys demonstrate that large areas of suitable fish spawning habitats are lost due to dams. In Trondheimsfjorden, numerous (mainly unregistered) dams are built for fish hatcheries that are no longer in operation and thus cause unnecessary fragmentation of anadromous river systems. Our two examples of potential restoration targets in Trondheimsfjorden (i.e., Kaldvella in Gaula river system and Dragvatnet in Hitra) demonstrate how barrier removal or restoration would substantially increase the accessible spawning and nursing habitats for anadromous fish. In Drammenselva area with long history of mining, forestry and hydropower activities, a great proportion of suitable spawning and nursing habitats for brown trout and freshwater pearl mussel is lost due to damming of small streams. Some dams have naturally collapsed and thus create only partial migration barriers for aquatic biota. However, the major and most difficult restoration targets are in the downstream river sections where even some very new dams block migratory fish. Various public institutions have collected information of man-made barriers in Norwegian watercourses. To support efficient and holistic planning and implementation of river restoration projects, these data should be gathered into a single, open-access database. Moreover, a user-friendly registration system (e.g. a mobile application) should be developed for mapping and reporting of old dams and other migration barriers (cf. “citizen-science project”). From an international perspective, Norway should become a more active member in present and future European river restoration projects (e.g. AMBER and Dam Removal Europe). This would help to increase public awareness and involvement, improve ecological status of riverine ecosystems and their valuable biota, and support fundamental applied science with wide international outreach.Eloranta, A., Thomassen, G., Bergan, M.A., Andersen, O. & Gregersen, F. 2019. Restaureringspotensial av gamle demninger i Norge. En pilotundersøkelse av forekomst, egenskaper og gjenopprettingspotensial i vassdrag med diadrome og stedegne fiskebestander. NINA Rapport 1628. Norsk institutt for naturforskning. Menneskeskapte vandringshindre er blant hovedårsakene til at vandrende fiskebestander (f.eks. laks Salmo salar, sjøørret Salmo trutta, og ål Anguilla anguilla) har blitt negativt påvirket eller utryddet i Norge. Dette gjelder spesielt i mindre elver, som er viktige for fiskeproduksjon, men ofte oversett av forvaltningsmyndighetene. I Norske vassdrag er restaurering og kartlegging av vandringshindre et viktig virkemiddel for å gjenopprette konnektivet og god økologisk status i disse mindre, men verdifulle økosystemene. Hovedformålet med dette pilotprosjektet er: (1) å kartlegge antall, plassering, karakteristika og restaureringspotensial for demninger som ikke lenger er i bruk, (2) å gi en oversikt over relevant litteratur og damprosjekter med tanke på å fjerne vandringshindre. Vi samlet data om demninger ved bruk av et åpent spørreskjema hvor folk kunne registrere demninger som ikke lenger var i bruk. Vi valgte også ut to områder for nærmere feltundersøkelser: (1) indre og ytre deler av Trondheimsfjorden med diadrome arter (f.eks. sjøørret, laks og/eller ål) og (2) Drammensvassdraget med sideelver med stedegne fiskebestander (i hovedsak ørret, men også elvemusling Margaritifera margaritifera, niøye Lampetra sp. og ål). Basert på spørreundersøkelsen og feltstudiene (n = 102 demninger), var bare 21% av de demningene vi har registrert blant de 3887 demningene som er registrert i DamPunkt-databasen til NVE. Dette betyr at det kan være totalt mer enn 18 000 demninger i Norge. Den gjennomsnittlige demningen i denne studien var bygd av betong eller stein og var typisk 1–10 m høy, 2–20 m bred og fungerte helt eller delvis som vandringsbarriere for fisk eller andre vannlevende organismer. De fleste av demningene er utnyttet for vannkraftformål, men flere hadde blitt bygd i forbindelse med annen aktivitet. Resultatene fra de to studieområdene viser tydelig at store bekke- og elvearealer egnet som gyteområder er utilgjengelige som følge av demninger i vassdragene. I Trondheimsfjordområdet er flere demninger som ikke lenger er i bruk (og som ikke finnes i NVE sin DamPunkt-database) bygget på grunn av fiskeoppdrett. Disse fører til en fragmentering av anadrom strekning og reduserer gyte- og oppvekstområder. To eksempler (Kaldvella i Gaula og Dragvatnet på Hitra) viser hvordan fjerning av demninger som ikke lenger er i bruk kan øke arealet av de tilgjengelige gyte- og oppvekstområder. I Drammenselvas nedbørsfelt er en stor andel av egnede gyte- og oppvekstområder for ørret og elveperlemusling gjort utilgjengelige på grunn av gruvedrift, tømmerfløting og vannkraft. Noen av demningene har i dag kollapset og utgjør et delvis vandringshinder for vannlevende organismer. De største vandringshindrene ligger i de nedre deler av tilløpselvene (f.eks. Dørja, Bingselva og Hoenselva), der demninger (noen nokså nye), hindrer vandring. Ulike institusjoner i Norge (f.eks. NVE, Statens vegvesen, Fylkesmannen, kommuner og forskningsinstitusjoner) har samlet informasjon om menneskeskapte vandringshindre i vassdrag over hele Norge. For å sikre effektiv og helhetlig planlegging og gjennomføring av elverestaurerings-prosjekter, bør slike data samles i en felles, åpen database. Videre bør det utvikles et brukervennlig registreringssystem (f.eks. en norsk mobilapp) for å tilrettelegge for en storskala kartlegging av vandringshindre i Norge (som “folkeforskningsprosjekt”). Norge burde bli mer aktiv i på-gående og fremtidige europeiske elverestaureringsprosjekter (som AMBER eller Dam Removal Europe). En slik strategi vil bidra til å øke folks bevissthet og involvering i restaureringsprosjekter, forbedre økologisk status i mange vassdrag med tanke på fisk og andre akvatiske organismer, og støtte grunnleggende anvendt forskning med bred, internasjonal rekkevidde

Typeeksempler på ombygging av dammer i små nedbørfelt for flomdemping

Foreliggende rapport er et FoU‐prosjekt for NVE om muligheter for ombygging av eksisterende dammer i små vassdrag for flomdemping. Hensikten er å se nærmere på hypotesen om at dammer etter ombygging, og primært med selvregulering, kan være et alternativ til eller supplere tradisjonelt flomvern noe som igjen vil gi en bedre arealutnyttelse og uendret økologisk status i vassdraget. Rapporten tar for seg hva som kan oppnås av flomdemping i ulike situasjoner, hvilke skader kan en forvente å få redusert og tilknyttede kostnader. Det sees videre på hvilke andre hensyn som må tas og hvilke rammer et ombyggingstiltak bør gjennomføres innenfor. Vi har gjort en vurdering av de vanligste damtypene i små vassdrag og gitt noen eksempler på tiltak. Blant tiltakene finnes både tradisjonelle og mer utradisjonelle løsninger, som f.eks. bruk av gabioner som vil «tilbakeholde» mindre flommer, men som likevel tåler overtopping ved ekstremflommer. Vi har sett på i hvilke situasjoner det kan være aktuelt å bruke eksisterende dammer til flomdemping. Viktige faktorer her er hydrologien og avstanden mellom dammen og skadeområdet. Dersom restfeltet mellom dam og skadeområde blir for stort, vil selv en stor demping i magasinet få liten virkning på skadeflommen. Vi har i forbindelse med denne studien utarbeidet et verktøy for grovsortering av kandidater av eksisterende magasiner som kan ha tilstrekkelig flomdempingspotensial. Demping kan oppnås både ved heving og senkning i forhold til den etablerte praksisen. Hva som foretrekkes vil avhenge av damtype og magasinforhold, samt hvordan de fysiske tiltakene og endringer i magasinvannstand og vannføring nedstrøms vil påvirke miljø og samfunn. Ved tilstrekkelig kunnskap om vassdraget og tilgrensende områder, samt god planlegging, kan tiltaket i mange tilfeller planlegges slik at det ikke påvirker allmenne interesser i en grad som ikke kan aksepteres. Dette inkluderer f.eks. estetisk utforming, tilrettelegging for friluftsliv, bevaring av kulturminner og verdifullt naturmangfold. Videre kan tiltaket ofte gjennomføres uten at det medfører endret økologisk tilstand i vassdraget siden vi her snakker om allerede eksisterende dammer. Det mest følsomme kvalitetselementet for denne type tiltak vil ofte være fisk. Rapporten er skrevet som et grunnlag for å vurdere om denne type tiltak er gjennomførbare og har en hensikt. Det er etter vår vurdering sannsynligvis et betydelig antall dammer der de fysiske tiltakene som må gjennomføres er overkommelige og sannsynligvis rimelige i forhold til nytteverdien sammenlignet med tradisjonelle flomsikringstiltak. Det må før iverksetting av tiltak undersøkes om tiltaket er konsesjonspliktig eller krever tillatelse etter annen lovgivning

Hepatic magnetic resonance T1-mapping and extracellular volume fraction compared to shear-wave elastography in pediatric Fontan-associated liver disease

Abstract Background Children with Fontan circulation are at risk of developing hepatic fibrosis/cirrhosis. Reliable noninvasive monitoring techniques are lacking or under development. Objective To investigate surrogate indicators of hepatic fibrosis in adolescents with Fontan circulation by evaluating hepatic magnetic resonance (MR) T1 mapping and extracellular volume fraction measurements compared to US shear-wave elastography. Materials and methods We analyzed hepatic native T1 times and extracellular volume fractions with modified Look-Locker inversion recovery. Liver stiffness was analyzed with shear-wave elastography. We compared results between 45 pediatric patients ages 16.7±0.6 years with Fontan circulation and 15 healthy controls ages 19.2±1.2 years. Measurements were correlated to clinical and hemodynamic data from cardiac catheterization. Results MR mapping was successful in 35/45 patients, revealing higher hepatic T1 times (774±44 ms) than in controls (632±52 ms; P &lt;0.001) and higher extracellular volume fractions (47.4±5.0%) than in controls (34.6±3.8%; P &lt;0.001). Liver stiffness was 1.91±0.13 m/s in patients vs. 1.20±0.10 m/s in controls ( P &lt;0.001). Native T1 times correlated with central venous pressures (r=0.5, P =0.007). Native T1 was not correlated with elastography in patients (r=0.2, P =0.1) or controls (r = −0.3, P =0.3). Extracellular volume fraction was correlated with elastography in patients (r=0.5, P =0.005) but not in controls (r=0.2, P =0.6). Conclusion Increased hepatic MR relaxometry and shear-wave elastography values in adolescents with Fontan circulation suggested the presence of hepatic fibrosis or congestion. Central venous pressure was related to T1 times. Changes were detected differently with MR relaxometry and elastography; thus, these techniques should not be used interchangeably in monitoring hepatic fibrosis