The composition and structure of a component community can vary widely across host populations of the same host species. Revealing the causes and consequences of geographical variation in parasite community composition is of great importance in order to determine parasites role in an ecosystem. Divergence in parasite infections among sympatric polymorphic Arctic charr is commonly associated with ...

Parasites play a key role in the biodiversity and dynamics of an ecosystem, either by affecting host mortality and/or host reproduction. Spawning comes with a great cost in time and energy, and in times of poor conditions this time and energy is better directed into growth and survival to increase future success. The phenomenon of skipped spawning, where sexually mature fish skip a reproductive ...

Allopatrisk ørret og røye i innsjøer er økologisk svært like med hensyn på nærings- og habitatpreferanser. I allopatri foretrekker begge artene å beite bunndyr i de littorale delene av innsjøen. I sympatri observeres ofte en segregering i nærings- og habitatvalg mellom ørret og røye, der røya skifter fra det prefererte habitatet, og går over til å beite mer zooplankton i de pelagiale delene av ...

An increased pressure of human activities that can introduce new infectious agents and therefore alter host-pathogen interactions, resulting in epizootics and biodiversity loss, challenges the Southern Ocean. Health status information and the potential effect of disease outbreaks in the Southern Ocean fauna is scare and evaluating the susceptibility to new infectious agents is decisive for its ...

Reindeer (Rangifer tarandus tarandus) inhabit the Arctic and have evolved adaptions to meet the climatic challenges in this region. Peripheral heterothermia, which is a heat conserving mechanism in homeotherms during cold exposure, is well documented in the reindeer and manifests itself in tissue temperatures in the extremities well below 10°C. It is, however, unknown whether peripheral heteothermia ...

The pineal gland is part of the endocrine system involved with rhythmic activity in e.g. fish. The main product of the pineal gland is the indole hormone melatonin, synthesised from the amino acid tryptophan. Melatonin is mainly synthesized when it is dark, as light inhibit the production. For this reason melatonin is thought to be strongly involved in biological rhythms. Arctic charr (Salvelinus ...

The once pristine Arctic is now facing negative alterations with a rapidly changing climate, increasing human activity, and plastic pollution. Seabirds are intrinsic to the marine ecosystems, and in recent years, plastic ingestion by seabirds has been of increasing concern because of the potential negative impact on individual and population levels. The aim of this study was to investigate the plastic ...

Russiske forskere introduserte kongekrabben, Paralithodes camtschaticus, til Barentshavet på 1960 og 1970-tallet for å gi lokale fiskere en ny art å høste av. Det var antatt at spredning til norske farvann var lite sannsynlig. Artens etablering ble en suksess sett fra russisk side. Kongekrabben har nå spredt seg over hele kysten av Finnmark fylke, og Porsangerfjorden er den siste av fjordene ...

Anthropogenic and natural stressors can affect ecosystems negatively and it is therefore important to have a clear understanding of the responses of organisms to stressors. The Northern Goshawk (Accipiter gentilis) is a common raptor species of the boreal forest ecosystem and its location at the top of its food chain makes it a special target for two important stressors; endoparasitism and environmental ...

Predator aversion is an important adaptation that can significantly lower the mortality rate among prey animals, but avoiding a predator requires knowing and recognizing them. The predator aversion of Common gulls and Mallard ducks at Prestvannet Lake, Tromsø, Northern Norway was tested in an experiment by placing differing objects resembling snakes next to bread during the summer and autumn of 2017. ...