Processing of detritus is an important ecosystem function in freshwaters. In rivers and streams, the activity of shredding invertebrates play an important role in processing of coarse-particulate organic matter such as leaf litter. In stream food webs, fish may act as top predators and control activity of consumers such as shredders top down. This top-down effect may be of a directly consumptive nature, ...

Studying baleen whales is challenging and complex, where observation of their habitat, sensory modalities, behavior and physiology, are infrequent and brief. The biochemical and biophysical contribution of mysticetes serve a vital role in maintaining a healthy marine ecosystem, but they are facing anthropogenic threats. Before giving any indications of how these threats affect the baleen whales, it ...

Predation is known to be one of the most important causes of nest failure in ground nesting birds, and many populations are experiencing a decline in breeding success worldwide. Predator abundance are expected to be highest closer to productive areas (i.e. Ecosystem exploitation hypothesis), and vary according to the availability of other prey (i.e. Alternative prey hypothesis). I hypothesized that ...

Stable isotope analysis has been used to examine marine food webs since the 1980s and has become a valuable tool for studying carbon sources and trophic structures in benthic food chains in the Arctic. Prior to the present study, no one has used stabile isotope analysis to test for a difference in the main carbon source or trophic structure along a depth gradient in the Arctic. Carbon sources (pelagic ...

Abstract The Arctic ecosystems and its species are under increased anthropogenic pressure from both climate change and industrial activities. Of special interest is pollution from petrogenic substances, and in particular accidental oil spills, that pose a risk to arctic marine organisms. An oil spill in the Arctic may see crude oil encapsulated into the sea ice and over time leaching to surface ...

The rich broadleaved forests of North Norway have high species diversity. Mappings of biodiversity have been undertaken in the two municipalities Målselv and Bardu, but these mappings are far from exhaustive. This study examines classification methods for mapping rich broadleaved forests with the use of Landsat ETM+ images, and with vegetation indices as ancillary data. Three classifications were ...

In this thesis, shift in diet of Arctic foxes on Svalbard over a long time frame was analyzed. The Svalbard Arctic fox is a generalist who links the terrestrial and marine ecosystems. The objectives were 1) investigate whether there are spatial and temporal trends in Arctic fox diet on Svalbard, 2) determine how important the changes in the environmental variables are for dietary shifts of the Arctic ...

Actuarial senescence is the irreversible decline of survival with increasing age. This phenomenon varies widely between taxa and species along the slow-fast continuum. However, inter-populational senescence differences have been less investigated, especially in the avian order. Here, I compared senescence rate between three contrasting populations of the Atlantic puffin (Fratercula arctica), and ...

The Atlantic salmon (Salmo salar L.) is a commercially important species that exhibits an anadromous life cycle involving migratory movements between freshwater and marine environments. Understanding the fundamental biology of the Atlantic salmon, particularly during key life history transitions such as smoltification, is therefore of great importance. In light of modern biotechnology and the completed ...

Circadian rhythms regulate living organisms over a 24h period. From daily activity to cellular function. The polar regions are subject to different photoperiods across the year, which impact the environmental conditions on a seasonal and daily basis. Evidence of crosstalk between circadian core clock genes and hypoxia with genes involved the mitochondrial dynamics, as well as oxygen sensing, provide ...