In all organisms, biological rhythms arise from the interaction between endogenous clocks and a rhythmic environment. The timing of sunrise and sunset synchronize internal timing processes and inform the organism not only of the time of day, but also of the time of year. For animals living in polar regions biological timekeeping represents a challenge, given that the sun does not rise during the ...

Species distribution models are a key tool in predicting and projecting population changes in the past, present and future. In the past they have mostly focused on using abiotic interactions for their models. This may be inadequate however as biotic interactions play an important role in determining community composition. Climate change has created and will create many novel communities that have ...

Aim Despite the numerous studies on corvids’ behaviour, their dynamics in different ecosystems is unknown. Ravens and hooded crows are opportunistic generalists acting as both predators and scavengers. Ravens are probably the most specialized scavengers on ungulate carcasses and both species are known as efficient hunters of small rodents. Small rodents are a key species in the tundra as they represent ...

Persistent organic pollutants (POPs) reach the Arctic ecosystems from lower latitudes mostly via air and ocean currents. They biomagnify through Arctic food webs and reach considerably high concentrations in top predators such as polar bears (Ursus maritimus). Although many of these compounds have been banned or restricted for decades, concentrations of polychlorinated byphenyls (PCBs), organochlorine ...

This study investigated the presence and activity of the components of the microbial food web (sepcifically viruses, heterotrophic bacteria and nanoflagellates, and autotrophic Cyanobacteria and pico-nanoflagellates) in the waters around the Svalbard archipelago (Norway) during the polar night period. The study focused on two major questions – are there differences in the community composition in ...

The snow crab (Chionoecetes opilio, O. Fabricius 1788) relatively recently (first reports in 1996) established a population in the Barents Sea. Both the populations size and distribution area have drastically increased since then, and the species is now distributed over large parts of the northern and eastern Barents Sea, and further expansion northward and westward has been predicted. Despite an ...

Among phocids, the hooded seal has the most extreme lactation period. It lasts, for most pups, four days, making it also the shortest lactation period of any mammal. During the lactation period, there is a high energy transfer, which affects and changes the body of the pup in preparation for the following post-weaning fast period. With regard to the decline of the West Ice population, the main purpose ...

As a result of climate change, the Arctic faunas of the Northeast Atlantic have begun to shift in an Atlantic direction. One system exposed to such a change is the Northeast Greenland (NEG) Shelf. However, the colonisation route taken by boreal fauna to the NEG shelf is unknown. This knowledge is essential to predict to what extent boreal fauna will dominate Arctic habitats, and alter ecosystems in ...

Life history strategies of polymorphic Arctic charr in two sub-arctic lakes (Tårnvatn and Skøvatn) with similar environmental- and physiochemical conditions were studied. Disparities in life history traits may reflect ecological adaptations and is suggested an important factor in the incipient speciation process. In this region several lakes have polymorphic charr, and the designation of a fish to ...

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 ...