Reassessing the definition of basal metabolic rate: Circadian considerations in avian studies.

The importance of daily fluctuations in avian basal metabolic rate (BMR) was introduced in the classic paper by Aschoff and Pohl (1970) characterizing circadian differences. Since that time, there has been a shift in the BMR literature to accept only values measured in the ρ- (resting) phase of the day as true BMR. We argue that α- (active) and ρ-phases both represent BMR, analogous to the plasticity of BMR seen in seasonal variations, or associated with changes in body composition and restrictions in diet.

Assessing the effects of climate on host-parasite interactions: a comparative study of European birds and their parasites.

Background: Climate change potentially has important effects on distribution, abundance, transmission and virulence of parasites in wild populations of animals.

Methodology/principal Finding: Here we analyzed paired information on 89 parasite populations for 24 species of bird hosts some years ago and again in 2010 with an average interval of 10 years. The parasite taxa included protozoa, feather parasites, diptera, ticks, mites and fleas.

Persistent organic pollutants in ringed seals from the Russian Arctic.

Organochlorine compounds total DDT (ΣDDT), total HCH isomers (ΣHCH), toxaphenes (sum of Parlar 26, 50, 62), mirex, endrin, methoxychlor, total chlorinated benzenes (ΣCBz), total chlordane compounds (ΣCHL), polychlorinated biphenyls (total of 56 congeners; ΣPCBs), polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), and polybrominated diphenyl ethers (sum of 7 tri- to hepta congeners; ΣPBDEs) were analysed in the blubber of adult ringed seals from the four areas of the Russian Arctic (White Sea, Barents Sea, Kara Sea and Chukchi Sea) collected in 2001-2005. Ringed seals from the south-western part of the Kara Sea (Dikson Island - Yenisei estuary) were the most contaminated with ΣDDTs, ΣPCBs, ΣCHL, and mirex as compared with those found in the other three areas of Russian Arctic, while the highest mean concentrations of ΣHCHs and PCDD/Fs were found in the blubber of ringed seals from the Chukchi Sea and the White Sea, respectively. Among all organochlorine compounds measured in ringed seals from the European part of the Russian Arctic, concentrations of ΣDDT and ΣPCBs only were higher as compared with the other Arctic regions.

Scale-dependent response diversity of seabirds to prey in the North Sea.

Functional response diversity is defined as the diversity of responses to environmental change among species that contribute to the same ecosystem function. Because different ecological processes dominate on different spatial and temporal scales, response diversity is likely to be scale dependent. Using three extensive data sets on seabirds, pelagic fish, and zooplankton, we investigate the strength and diversity in the response of seabirds to prey in the North Sea over three scales of ecological organization.

Effects of hydrographic variability on the spatial, seasonal and diel diving patterns of southern elephant seals in the eastern Weddell Sea.

Weddell Sea hydrography and circulation is driven by influx of Circumpolar Deep Water (CDW) from the Antarctic Circumpolar Current (ACC) at its eastern margin. Entrainment and upwelling of this high-nutrient, oxygen-depleted water mass within the Weddell Gyre also supports the mesopelagic ecosystem within the gyre and the rich benthic community along the Antarctic shelf. We used Conductivity-Temperature-Depth Satellite Relay Data Loggers (CTD-SRDLs) to examine the importance of hydrographic variability, ice cover and season on the movements and diving behavior of southern elephant seals in the eastern Weddell Sea region during their overwinter feeding trips from Bouvetøya.

Relationships between metabolic status, corticosterone secretion and maintenance of innate and adaptive humoral immunities in fasted re-fed mallards.

The prolonged exposure of birds to environmental stressors known to affect energy status and glucocorticoid secretion may have several physiological consequences including a decrease in immunocompetence, further compromising the survival of individuals. However, the relationships between these parameters remain poorly understood. To this end, changes in body energy content, plasma corticosterone, adaptive (total plasma immunoglobulin Y; IgY) and innate (natural antibodies; NAbs) immune systems were assessed in female mallards (Anas plathyrhynchos) throughout prolonged fasts of different intensities and subsequent re-feeding.

Salmon farms as a source of organohalogenated contaminants in wild fish.

Organohalogenated contaminants (OHCs), including organochlorines (OCs; PCB, and OC-pesticides), brominated flame retardants (BFRs; polybrominated diphenyl ethers [PBDE], hexabromocyclododecane [HBCD]) and perfluorooctane sulfonate (PFOS), were measured in livers of Atlantic cod (Gadus morhua) and saithe (Pollachius virens) caught in the vicinity of salmon farms (n = 75) and control sites (n = 80) in three regions (59°-70°N) in Norway. Forty-five percent of the farm-associated (FA) fish (60% of the saithe and 30% of the cod) and none of the control fish had salmon feed (aquaculture food pellets) in their digestive tracts. Concentrations of OCs and BFRs were about 50% higher and dominated more by persistent compounds in Atlantic cod compared to saithe.

Relationship between persistent halogenated organic contaminants and TCDD-toxic equivalents on EROD activity and retinoid and thyroid hormone status in northern fulmars.

We investigated whether the hepatic cytochrome P450 1A activity (measured as 7-ethoxyresorufin-O-deethylase (EROD)) and plasma thyroid hormone and liver retinoid concentrations were explained by liver and blood levels of halogenated organic contaminants (HOCs) in free-ranging breeding northern fulmars (Fulmarus glacialis) from Bjørnøya in the Norwegian Arctic. Hepatic EROD activity and liver levels of 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalents (TEQs) were positively correlated, suggesting that hepatic EROD activity is a good indicator for dioxin and dioxin-like HOC exposure in breeding northern fulmars. There were not found other strong relationships between HOC concentrations and hepatic EROD activity, plasma thyroid or liver retinoid concentrations in the breeding northern fulmars.

Volatile siloxanes in the European arctic: assessment of sources and spatial distribution.

The purpose of this study was to investigate presence and potential accumulation of cyclic volatile methyl siloxanes (cVMS) in the Arctic environment. Octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) were analyzed in sediment, zooplankton, Atlantic cod (Gadus morhua), shorthorn sculpin (Myxocephalus scorpius), and bearded seal (Erignathus barbatus) collected from the Svalbard archipelago within the European Arctic in July 2009. Highest levels were found for D5 in fish collected from Adventfjorden, with average concentrations of 176 and 531 ng/g lipid in Atlantic cod and shorthorn sculpin, respectively.

Predator-prey reversal: a possible mechanism for ecosystem hysteresis in the North Sea?

Removal of large predatory fishes from marine ecosystems has resulted in persistent ecosystem shifts, with collapsed predator populations and super-abundant prey populations. One explanation for these shifts is reversals of predator-prey roles that generate internal feedbacks in the ecosystems. Pelagic forage fish are often predators and competitors to the young life stages of their larger fish predators.

Comparative endocrine disruptive effects of contaminants in ringed seals (Phoca hispida) from Svalbard and the Baltic Sea.

We investigated variables related to thyroid, vitamin A and calcitriol homeostasis, immune function and tumour development in ringed seals (Phoca hispida) from the polluted Baltic Sea and a less polluted reference location at Svalbard, Norway. We also examined the relationships between the biological variables and the concentrations of persistent organic pollutants (POPs) and their hydroxylated (OH) metabolites. Our data show higher plasma concentrations of free triiodothyronine (T3), and ratios of free and total T3 in Baltic seals as compared to Svalbard seals.

The relationship between ultraviolet radiation exposure and vitamin D status.

This paper reviews the main factors influencing the synthesis of vitamin D, with particular focus on ultraviolet radiation exposure. On the global level, the main source of vitamin D is the sun. The effect of solar radiation on vitamin D synthesis depends to some extent on the initial vitamin D levels.

Icing events trigger range displacement in a high-arctic ungulate.

Despite numerous studies of how climate change may affect life history of mammals, few have documented the direct impact of climate on behavior. The Arctic is currently warming, and rain-on-snow and thaw-freeze events leading to ice formation on the ground may increase both in frequency and spatial extent. This is in turn expected to be critical for the winter survival of arctic herbivores.

Seasonal baseline levels of physiological and biochemical parameters in polar cod (Boreogadus saida): Implications for environmental monitoring.

Seasonality of biomarker baseline levels were studied in polar cod (Boreogadus saida), caught in Kongsfjorden, Svalbard, in April, July, September and December, 2006-2007. Physiological parameters (condition factor, gonado- and hepato-somatic indexes, energy reserves, potential metabolic activity and antifreeze activity) in polar cod were used to interpret the seasonality of potential biomarkers. The highest levels of ethoxyresorufin-O-deethylase (EROD) activity occurred concomitantly with the highest potential metabolic activity in July due to e.

EROD activity in liver and gills of polar cod (Boreogadus saida) exposed to waterborne and dietary crude oil.

Polar cod Boreogadus saida an indicator species for biomonitoring in the Arctic was exposed to crude oil in waterborne and dietary experiments. Ethoxyresorufin O-deethylase (EROD) activity was measured in liver and gills of polar cod at weeks 0, 2 and 4 of exposure and following 2 weeks of depuration. EROD increased significantly and dose-dependently in both tissues through both exposure routes.

Climate variability and temporal trends of persistent organic pollutants in the arctic: a study of glaucous gulls.

The impact of climate variability on temporal trends (1997-2006) of persistent organic pollutants (POPs; polychlorinated biphenyls [PCB], hexachlorobenzene [HCB], and oxychlordane) was assessed in glaucous gulls (Larus hyperboreus) breeding in the Norwegian Arctic (n = 240). The Arctic Oscillation (AO: an index of sea-level pressure variability in the Northern Hemisphere above 20 degrees N) with different time lags was used as a climate proxy. The estimated concentrations of POPs in glaucous gull blood/plasma declined substantially (16-60%) over the time period.

Strongly increasing blood concentrations of lipid-soluble organochlorines in high arctic common eiders during incubation fast.

Female common eiders (Somateria mollissima) starve during the nesting stage and may loose 30-45% of their initial body mass, mostly through lipid mobilization. In this study, the effects of fasting on the blood concentrations of three lipid-soluble organochlorines (OCs: polychlorinated biphenyl [PCB]-153; 1-dichloro-2,2-bis (p-chlorophenyl) ethylene [p,p'-DDE]; and hexachlorobenzene [HCB]) were examined in eiders breeding in the high Arctic. Blood samples were taken from females (n=47) at day 5 and day 20 of the incubation period.

Observational evidence of risk-sensitive reproductive allocation in a long-lived mammal.

Organisms should adopt a risk-sensitive reproductive allocation when summer reproductive allocation competes with survival in the coming winter. This trade off is shown through autumn female body mass, which acts as an insurance against unpredictable winter environmental conditions. We tested this hypothesis on female reindeer in a population that has experienced a time period of dramatic increase in abundance.

Biomarker responses in polar cod (Boreogadus saida) exposed to the water soluble fraction of crude oil.

In order to mimic the biological effects of an oil spill in Arctic waters, we examined several types of biomarkers (genes, enzymes, metabolites, and DNA damage) in polar cod Boreogadus saida experimentally exposed to the water soluble fractions of crude oil. During 4 weeks of exposure, induction of the studied biomarkers exceeded baseline levels. The mRNA expression of the cytochrome P4501A1 (cyp1a1) gene was the most promising biomarker, with glutathione S-transferase (gst) as a suitable complement.

Short- and long-term consequences of reproductive decisions: an experimental study in the puffin.

The purpose of the present study was to inspect the response of the Atlantic Puffin (Fratercula arctica) to an experimental manipulation of the investment needed to successfully raise an offspring. We achieved this by replacing an old offspring with a younger chick, and vice versa, thereby prolonging and shortening the chick-rearing period. To examine any costs of reproduction we then followed the breeding success, the recruitment of young to the population, and the survival of parents for 11 years following the manipulation.

Biomarker responses in polar cod (Boreogadus saida) exposed to dietary crude oil.

Polar cod Boreogadus saida were exposed weekly to two doses of dietary crude oil for 4 weeks followed by 2 weeks of depuration. Administered doses corresponded on average to 4 and 9microgSigmaPAHsg(-1)fishweek(-1). Cytochrome P4501A1 (cyp1a1) and glutathione S-transferase (gst) mRNA expression, ethoxyresorufin O-deethylase (EROD) activity and metabolites in the bile showed strong and dose-dependent inductions at 2 and 4 weeks of exposure.

Perfluorinated and other persistent halogenated organic compounds in European shag (Phalacrocorax aristotelis) and common eider (Somateria mollissima) from Norway: a suburban to remote pollutant gradient.

Samples of two marine bird species, European shag (Phalacrocorax aristotelis) and common eider (Somateria mollissima) sampled at a remote coastal site in Norway were analysed for POPs and PFCs. Additionally samples of common eider were analysed from two other locations in Norway, representing a gradient from "densely populated" to "remote". The variety, concentration and distribution of lipophilic POPs in comparison to PFCs were investigated.

Hormone, vitamin and contaminant status during the moulting/fasting period in ringed seals (Pusa [Phoca] hispida) from Svalbard.

This study investigates the potential effects of moulting, and the concomitant period of fasting undertaken by ringed seals, on hormone, vitamin and contaminant status in adult animals in a population from Svalbard, Norway, which has relatively low contaminant levels. Concentrations of circulating total and free thyroxine and triiodothyronine, circulating and hepatic vitamin A, hepatic persistent organic pollutants and their circulating hydroxyl metabolites were higher in moulting seals compared to pre-moulting seals. The opposite trend was observed for body condition, circulating calcitriol levels and hepatic mRNA expression of thyroid hormone receptor beta.

Quantitative structure - photodegradation relationships of polybrominated diphenyl ethers, phenoxyphenols and selected organochlorines.

Among other developments, the technological revolution has lead to introduction of new chemicals to better serve in instruments and materials. The consequences of the extensive increase in use of new chemicals can be detected in the environment world wide, i.e.

Intestinal parasites of the Arctic fox in relation to the abundance and distribution of intermediate hosts.

The intestinal parasite community of Arctic foxes (Vulpes lagopus) on the Svalbard archipelago in the High Arctic was investigated in relation to the abundance and distribution of intermediate hosts. Five species of cestodes (Echinococcus multilocularis, Taenia crassiceps, Taenia polyacantha, Taenia krabbei and Diphyllobothrium sp.), ascaridoid nematodes and one unidentified acanthocephalan species were found.