Search results for "joki"
showing 10 items of 103 documents
Rehabilitation of two northern river lamprey (Lampetra fluviatilis) populations impacted by various anthropogenic pressures : lessons learnt in the p…
2019
The pioneering work done during the past three decades in the regulated Rivers Perhonjoki and Kalajoki, Finland, to study and rehabilitate river lamprey populations is presented. The effects of various anthropogenic activities and rehabilitation measures are evaluated based on habitat surveys and long-term monitoring of larval densities, numbers of adults migrating upstream and of transformers migrating downstream. Telemetric tracking and tagging experiments were used to determine the efficacy of fishways. Lamprey populations in both rivers decreased in the 1980s and 1990s. This was linked to obstructed upstream migration of adults and deterioration of habitats for different life stages due…
The endangered freshwater pearl mussel Margaritifera margaritifera shows adaptation to a local salmonid host in Finland
2022
1. The freshwater pearl mussel Margaritifera margaritifera (FPM) is an endangered unionid which has a glochidium larva that attaches to the gills of Atlantic salmon Salmo salar or brown trout S. trutta, although some FPM populations have been shown to exclusively attach to only one of these species. The origin of host fish populations may be crucial for conservation actions for this mussel species, but the relative suitability of local (sympatric) and non- local (allopatric) salmonid populations as the hosts for FPM has been studied only rarely. We hypothesised that FPM glochidia would show adaptation to local salmonid strains and, there-fore, that they would be more successful (abundant, l…
Immunization of trout (Salmo trutta) against freshwater pearl mussel (Margaritifera margaritifera) by duck mussel (Anodonta anatina) glochidia
2013
Freshwater pearl mussel Margaritifera margaritifera is endangered throughout its range of distribution in Europe. In some rivers M. margaritifera may co-occur with the duck mussel Anodonta anatina. Brown trout Salmo trutta serves as suitable fish host for both mussel species. Thus it is possible that exposure of brown trout to A. anatina glochidia might increase resistance of fish against M. margaritifera glochidia. The aim was to test this ‘cross immunity hypothesis’. Brown trout were immunized by duck mussel (Anodonta anatina) glochidia in late May. Then brown trout were challenged by pearl mussel (Margaritifera margaritifera) glochidia in late August after the A. anatina glochidia were d…
Harjuskannan tila ja luonnonvaraisen lisääntymisen mahdollisuudet Kokemäenjoessa
2008
Tilaushistorioiden tekijöiden kirjoittajaidentiteetit ja identiteettien rakentuminen
2014
Maisterintutkielmassani tutkin suomalaisten tilaushistorioita kirjoittaneiden henkilöiden kirjoittajaidentiteettiä ja näiden identiteettien rakentumista. Tutkimukseni aineisto on hankittu sähköisellä kyselyllä, johon kutsuttiin noin 80 vastaajaa Suomen tietokirjailijat ry:n kautta sekä suoraan sähköpostikutsuilla omien kontaktieni avulla. Kyselyyn vastasi 39 henkilöä. Kysely koostui sekä monivalintakysymyksistä että avoimista kysymyksistä. Kysymysten avulla kartoitettiin ensin vastaajien taustaa (ikä, sukupuoli, koulutus, työelämä) ja sitten heidän omia kokemuksiaan tilaushistorioiden kirjoittamisesta. Vastausten analysointiin olen käyttänyt niin sanottua grounded theory -lähestymistapaa. T…
Interactions between two parasites of brown trout (Salmo trutta): Consequences of preinfection
2018
Preinfection by one parasitic species may facilitate or by contrast hamper the subsequent penetration and/or establishment of other parasites in a host. The biology of interacting species, timing of preinfection, and dosage of subsequent parasite exposure are likely important variables in this multiparasite dynamic infection process. The increased vulnerability to subsequent infection can be an important and often overlooked factor influencing parasite virulence. We investigated how the preinfection by freshwater pearl mussel Margaritifera margaritifera glochidia could influence the success of subsequent infection by the common trematode Diplostomum pseudospathaceum in brown trout Salmo tru…