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[{"key": "dc.contributor.advisor", "value": "Salonen, Jouni", "language": null, "element": "contributor", "qualifier": "advisor", "schema": "dc"}, {"key": "dc.contributor.advisor", "value": "Sj\u00f6nberg, Tuomo", "language": null, "element": "contributor", "qualifier": "advisor", "schema": "dc"}, {"key": "dc.contributor.advisor", "value": "Taskinen, Jouni", "language": null, "element": "contributor", "qualifier": "advisor", "schema": "dc"}, {"key": "dc.contributor.author", "value": "P\u00f6l\u00f6nen, Henna", "language": null, "element": "contributor", "qualifier": "author", "schema": "dc"}, {"key": "dc.date.accessioned", "value": "2025-06-19T05:49:23Z", "language": null, "element": "date", "qualifier": "accessioned", "schema": "dc"}, {"key": "dc.date.available", "value": "2025-06-19T05:49:23Z", "language": null, "element": "date", "qualifier": "available", "schema": "dc"}, {"key": "dc.date.issued", "value": "2025", "language": null, "element": "date", "qualifier": "issued", "schema": "dc"}, {"key": "dc.identifier.uri", "value": "https://jyx.jyu.fi/handle/123456789/103759", "language": null, "element": "identifier", "qualifier": "uri", "schema": "dc"}, {"key": "dc.description.abstract", "value": "Jokihelmisimpukka (Margaritifera margaritifera) eli raakku on luokiteltu Suomessa eritt\u00e4in uhanalaiseksi. Lajia uhkaa erityisesti sen elinalueiden heikkeneminen, kuten valuma-alueiden maank\u00e4yt\u00f6st\u00e4 johtuva kiintoaineksen kulkeutuminen jokiin. T\u00e4m\u00e4 on erityisen vahingollista jokipohjaan kaivautuneille poikasille, jotka tarvitsevat hapekkaan pohjan selviyty\u00e4kseen. Jokihelmisimpukan elinalueita onkin nykyisin pyritty parantamaan erilaisten kunnostusten avulla. T\u00e4m\u00e4n tutkimuksen tavoitteena oli selvitt\u00e4\u00e4 kahden Pohjois-Pohjanmaalla sijaitsevan raakkupuron jokipohjan soveltuvuutta jokihelmisimpukan poikasille ja kyseisill\u00e4 puroilla tehtyjen kunnostusten vaikutusta jokipohjien happioloihin ja poikasten menestymiseen. Koeasetelmassa viljeltyj\u00e4 jokihelmisimpukan poikasia asetettiin sek\u00e4 muokatuille poikassoraikkoalueille ett\u00e4 muokkaamattomille jokipohjille 1, 5 ja 10 cm syvyyksille poikaslevyill\u00e4 3 kk ajaksi. Alueilta arvioitiin my\u00f6s jokipohjien happiolot redox-mittarilla sek\u00e4 menetelm\u00e4tutkimusmieless\u00e4 my\u00f6s naulatestill\u00e4, mik\u00e4 osoittautui toimivaksi menetelm\u00e4ksi redox-mittauksen rinnalla. Norssipurossa poikasten selviytyminen oli 1 ja 5 cm syvyydess\u00e4, ja kasvu 5 ja 10 cm syvyydess\u00e4, parempaa poikassoraikkoalueilla kuin kontrollialueilla. Haukiojassa poikasten selviytymisess\u00e4 ei ollut eroa alueiden v\u00e4lill\u00e4, mutta kasvussa havaittiin ero 10 cm syvyydess\u00e4 poikassoraikkoalueiden hyv\u00e4ksi. Norssipuron poikassoraikkoalueilla oli my\u00f6s korkeammat redox-arvot 5 cm syvyydess\u00e4 ja syvemm\u00e4lle ulottuva ruoste nauloissa kuin kontrollialueilla, viitaten korkeampaan hapen m\u00e4\u00e4r\u00e4\u00e4n. Haukiojassa redox-arvoissa ei havaittu eroa poikassoraikko- ja kontrollialueiden v\u00e4lill\u00e4, mutta siell\u00e4kin ruoste ulottui nauloissa syvemm\u00e4lle poikassoraikkoalueilla kuin kontrollialueilla. Tulosten perusteella jokipohjien happioloja sek\u00e4 poikasten selviytymist\u00e4 ja kasvua voidaan parantaa elinymp\u00e4rist\u00f6kunnostusten, erityisesti poikasia varten kunnostettavien soraikkoalueiden, avulla. Tutkimuksessa huomattiin my\u00f6s alkupituudeltaan suurempien poikasten selviytyneen elossa pienempi\u00e4 poikasia paremmin, mik\u00e4 tulee huomioida laitoskasvatus- ja istutustoiminnassa jatkossa.", "language": "fi", "element": "description", "qualifier": "abstract", "schema": "dc"}, {"key": "dc.description.abstract", "value": "Freshwater pearl mussel (Margaritifera margaritifera) is classified as endangered species in Finland. The species is threatened especially by habitat deterioration, e.g. land-use of catchment areas that causes river bed siltation. This is especially harmful to juvenile mussels that are completely buried into the river bed and need oxygen rich habitat to survive. Therefore, new restoration methods for the habitats of freshwater pearl mussel have been developed and used today. The purpose of this study was to examine the suitability of the river beds of two Northern Ostrobothnian freshwater pearl mussel rivers for the juveniles. In addition, the effects of restoration for the oxygen conditions and survival and growth of juvenile mussels were investigated. Cultured juveniles were placed into the river beds in 1, 5 and 10 cm depths in juvenile plates for three months. Oxygen conditions in the same sites were assessed by measuring redox values, and also by using so-called nail test, a potential new method to estimate the oxygen conditions in river beds. In Norssipuro the survival of juveniles was higher in 1 and 5 cm depth, and growth in 5 and 10 cm depth, in the restored gravel beds compared to control sites. In Haukioja there was no difference in survival between the restored and control sites but growth was higher in restored beds between 10 cm depth zones. In Norssipuro the redox values were higher in 5 cm depth and there were more rust in the nails in restored than in control sites. In Haukioja there were no differences in redox values between study sites but there were more rust in the nails in restored than in control sites. The nail test was proven as a useful method to assess oxygen conditions inside river bed. Overall, the results indicate that oxygen conditions of river beds and thus survival and growth of juvenile freshwater pearl mussels can be improved by river restoration. In addition the survival of juveniles was higher among the individuals with larger size in the beginning of the experiment. This should be taken into account e.g. in releasing laboratory-produced juveniles in nature.", "language": "en", "element": "description", "qualifier": "abstract", "schema": "dc"}, {"key": "dc.description.provenance", "value": "Submitted by Paivi Vuorio (paelvuor@jyu.fi) on 2025-06-19T05:49:23Z\nNo. of bitstreams: 0", "language": "en", "element": "description", "qualifier": "provenance", "schema": "dc"}, {"key": "dc.description.provenance", "value": "Made available in DSpace on 2025-06-19T05:49:23Z (GMT). No. of bitstreams: 0\n Previous issue date: 2025", "language": "en", "element": "description", "qualifier": "provenance", "schema": "dc"}, {"key": "dc.format.extent", "value": "45", "language": null, "element": "format", "qualifier": "extent", "schema": "dc"}, {"key": "dc.language.iso", "value": "fin", "language": null, "element": "language", "qualifier": "iso", "schema": "dc"}, {"key": "dc.rights", "value": "In Copyright", "language": null, "element": "rights", "qualifier": null, "schema": "dc"}, {"key": "dc.subject.other", "value": "naulatesti", "language": null, "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.subject.other", "value": "poikaslevy", "language": null, "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.subject.other", "value": "poikassoraikko", "language": null, "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.subject.other", "value": "virtavesikunnostus", "language": null, "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.title", "value": "Jokipohjan laadun vaikutus jokihelmisimpukan (Margaritifera margaritifera) poikasten selviytymiseen ja kasvuun", "language": null, "element": "title", "qualifier": null, "schema": "dc"}, {"key": "dc.type", "value": "master thesis", "language": null, "element": "type", "qualifier": null, "schema": "dc"}, {"key": "dc.identifier.urn", "value": "URN:NBN:fi:jyu-202506195548", "language": null, "element": "identifier", "qualifier": "urn", "schema": "dc"}, {"key": "dc.contributor.faculty", "value": "Matemaattis-luonnontieteellinen tiedekunta", "language": "fi", "element": "contributor", "qualifier": "faculty", "schema": "dc"}, {"key": "dc.contributor.faculty", "value": "Faculty of Sciences", "language": "en", "element": "contributor", "qualifier": "faculty", "schema": "dc"}, {"key": "dc.contributor.department", "value": "Bio- ja ymp\u00e4rist\u00f6tieteiden laitos", "language": "fi", "element": "contributor", "qualifier": "department", "schema": "dc"}, {"key": "dc.contributor.department", "value": "Department of Biological and Environmental Science", "language": "en", "element": "contributor", "qualifier": "department", "schema": "dc"}, {"key": "dc.contributor.organization", "value": "Jyv\u00e4skyl\u00e4n yliopisto", "language": null, "element": "contributor", "qualifier": "organization", "schema": "dc"}, {"key": "dc.contributor.organization", "value": "University of Jyv\u00e4skyl\u00e4", "language": null, "element": "contributor", "qualifier": "organization", "schema": "dc"}, {"key": "dc.subject.discipline", "value": "Akvaattiset tieteet", "language": "fi", "element": "subject", "qualifier": "discipline", "schema": "dc"}, {"key": "dc.subject.discipline", "value": "Aquatic sciences", "language": "en", "element": "subject", "qualifier": "discipline", "schema": "dc"}, {"key": "dc.type.coar", "value": "http://purl.org/coar/resource_type/c_bdcc", "language": null, "element": "type", "qualifier": "coar", "schema": "dc"}, {"key": "dc.rights.copyright", "value": "\u00a9 The Author(s)", "language": "fi", "element": "rights", "qualifier": "copyright", "schema": "dc"}, {"key": "dc.rights.accesslevel", "value": "openAccess", "language": null, "element": "rights", "qualifier": "accesslevel", "schema": "dc"}, {"key": "dc.type.publication", "value": "masterThesis", "language": null, "element": "type", "qualifier": "publication", "schema": "dc"}, {"key": "dc.subject.yso", "value": "jokihelmisimpukka", "language": null, "element": "subject", "qualifier": "yso", "schema": "dc"}, {"key": "dc.rights.url", "value": "https://rightsstatements.org/page/InC/1.0/", "language": null, "element": "rights", "qualifier": "url", "schema": "dc"}]
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