Living organisms show seasonality in a wide array of functions such as reproduction, fattening, hibernation, and migration. At temperate latitudes, changes in photoperiod maintain the alignment of annual rhythms with predictable changes in the environment.The appropriate physiological response to changing photoperiod in mammals requires retinal detection of light and pineal secretion of melatonin, ...

Arctic summer sea ice extent is decreasing and thinning, forming melt ponds that cover more than 50% of the sea ice area during the peak of the melting season. Despite of this, ice algal communities in melt ponds are understudied and so are their contribution to the Arctic Ocean primary production and carbon turnover. While melt ponds have been considered as low productive, recent studies suggest ...

In the northern hemisphere, humpback whales (<i>Megaptera novaeangliae</i>) typically migrate between summer/autumn feeding grounds at high latitudes, and specific winter/spring breeding grounds at low latitudes. Northeast Atlantic (NEA) humpback whales for instance forage in the Barents Sea and breed either in the West Indies, or the Cape Verde Islands, undertaking the longest recorded mammalian ...

Three genetically discrete morphs of Arctic charr in Loch Rannoch, Scotland originated from a recent divergence within the lake (in situ) (piscivore and benthivore morphs) and from secondary contact of two older lineages (ex situ; a planktivore–piscivore/ benthivore divergence). To test if the expression of traits with strong functional roles was linked to the age of the divergence, fin and ...

Arctic wildlife is facing multiple stressors, including increasing plastic pollution. Seabirds are intrinsic to marine ecosystems, but most seabird populations are declining. We lack knowledge on plastic ingestion in many arctic seabird species, and there is an urgent need for more information to enable risk assessment and monitoring. Our study aimed to investigate the occurrence of plastics in ...

The muscle cells and extracellular matrices (ECMs) of two teleost-infecting blood flukes belonging to distinct evolutionary lineages of the Aporocotylidae (Digenea) were examined using Transmission Electron Microscopy. Four morphotypes of muscle cells were found in the freshwater species Sanguinicola sp., but were considered to be various developmental stages of a single cisternic type. In the marine ...

The Arctic is warming rapidly, with concomitant sea ice losses and ecosystem changes. The animals most vulnerable to Arctic food web changes are long-lived and slow-growing such as marine mammals, which may not be able to adapt rapidly enough to respond to changes in their resource bases. To determine the current extent and sources of these resource bases, we examined isotopic and trophic niches ...

Triploidy is induced in Atlantic salmon (Salmo salar) to produce sterile fish for genetic containment and to hinder early sexual maturation in farmed fish, but it can have unwanted negative effects on growth, health, and welfare. However, the growth and welfare of triploid fish may be improved by adjusting the rearing environment, feeding conditions and diets. This study evaluated physiological ...

The rhythm of life on earth is shaped by seasonal changes in the environment. Plants and animals show profound annual cycles in physiology, health, morphology, behaviour and demography in response to environmental cues. Seasonal biology impacts ecosystems and agriculture, with consequences for humans and biodiversity. Human populations show robust annual rhythms in health and well-being, and the ...

Arctic reindeer experience extreme changes in environmental light from continuous summer daylight to continuous winter darkness. Here, we show that they may have a unique mechanism to cope with winter darkness by changing the wavelength reflection from their tapetum lucidum (TL). In summer, it is golden with most light reflected back directly through the retina, whereas in winter it is deep ...