Geese are social birds and form pairs that can last a lifetime, being together throughout the year. Forming pairs and maintaining family groups increase the individual’s social status, giving it easier access to resources and more time to exploit them. Hence, social behaviour is favourable when pairs are building up body reserves before migrating to the breeding grounds as well as after breeding, ...

The current population-based food consumption models assume that harp seals are swallowing fish whole. However, behaviours such as belly-biting and rejection of fishes’ heads has been observed, possibly biasing diet analysis based on hard parts such as otoliths, and consequently underestimating the total food consumption of fish by harp seals. The purpose of this study was to examine whether individual ...

Salmon lice (Lepeophtheirus salmonis) are marine ectoparasites commonly found on salmonid species, where the infection levels on wild salmonids have dramatically increased the latest decade. Sea trout (Salmo trutta) is being used in salmon lice monitoring studies (e.g. NALO) where different sampling gears are used. The interaction between sea trout and lice is complicated, and therefore methodology ...

Tundra ecosystems are changing environments that are greatly affected by plant-herbivore relationships. Many herbivores of different sizes eat, trample or clip plants. However they can also act as support through nutrient addition by faeces. In this study I look at the impact of three sizes of herbivores (large, medium and small) on ten functional groups of plants (nitrogen-fixing forbs, erect ...

Current knowledge of the Arctic marine ecosystem is based primarily on studies performed during the polar day on the pelagic and benthic realms. Both the polar night and the hyperbenthic layer remain substantial knowledge gaps in the understanding of the marine system at high latitudes. To help address these knowledge gaps, this project investigates the hyperbenthic food web structure in Kongsfjord, ...

The effects of 48 hours exposure to mechanically and chemically dispersed oil on juvenile lumpsuckers, as well as the use of gill EROD activity and bile PAH metabolites as potential biomarkers were assessed in this study. This was done by measuring the gill EROD activity, bile PAH metabolites, plasma osmolality, plasma chloride concentration, and gill Na+/K+ATPase activity. The mechanical and ...

Lemmings are famous for their spectacular population cycles that causes waves of biomass through the arctic tundra. Both climate variability and the interaction with the sympatric grey-sided vole have been shown to effect lemming outbreaks. However little is known about the transferability of these effects between peaks. I analyzed the spatial variability using snap-trapping data from two ...

Increased human activities in the Arctic pose a high risk for Arctic organisms to be chronically exposed to petroleum compounds. The endocrine disrupting properties of some of these compounds coupled with the metabolic costs of detoxification may have negative effects on the long and energy intensive reproductive development of polar cod, an Arctic keystone species. In the present study, selected ...

Zooplankton is the link between primary producers and higher trophic levels, so it is of vital importance for the food chain. The strong seasonality in the Arctic affects the vertical distribution of zooplankton in the water column. Predators can also affect the vertical distributions of their prey in the water column due to avoidance adaptations. The importance of these differences between prey and ...

Arctic fox in inland areas has been typically described as a species dependent on rodent populations, but being able to use alternative prey, therefore named an opportunistic specialist. Rodent populations in the low shrub tundra of southern Yamal peninsula exhibit at present low amplitude cycles. The hypothesis for this thesis is that the low abundance of small rodents is not enough to sustain ...