Cecilie Miljeteig

Eggshell thinning and decreased concentrations of vitamin E are associated with contaminants in eggs of ivory gulls

The ivory gull is a high Arctic seabird species threatened by climate change and contaminant exposure. High levels of contaminants have been reported in ivory gull Pagophila eburnea eggs from Svalbard and the Russian Arctic. The present study investigated associations between high levels of contaminants (organochlorinated pesticides (OCPs), polychlorinated biphenyls (PCBs), brominated flame retardants (BFRs), perfluorinated alkyl substances (PFASs) and mercury (Hg)) and three response variables: eggshell thickness, retinol (vitamin A) and α-tocopherol (vitamin E). Negative associations were found between levels of OCPs, PCBs and BFRs and eggshell thickness (p<0.021) and α-tocopherol (p<0.023), but not with retinol (p>0.1). There were no associations between PFASs and mercury and the three response variables. Furthermore, the eggshell thickness was 7-17% thinner in the present study than in archived ivory gull eggs (≤1930). In general, a thinning above 16 to 20% has been associated with a decline in bird populations, suggesting that contaminant-induced eggshell thinning may constitute a serious threat to ivory gull populations globally.

Description of microsatellite markers and genotyping performances using feathers and buccal swabs for the Ivory gull (Pagophila eburnea)

We report 22 new polymorphic microsatellites for the Ivory gull (Pagophila eburnea), and we describe how they can be efficiently co‐amplified using multiplexed polymerase chain reactions. In addition, we report DNA concentration, amplification success, rates of genotyping errors and the number of genotyping repetitions required to obtain reliable data with three types of noninvasive or nondestructive samples: shed feathers collected in colonies, feathers plucked from living individuals and buccal swabs. In two populations from Greenland (n = 21) and Russia (Severnaya Zemlya Archipelago, n = 21), the number of alleles per locus varied between 2 and 17, and expected heterozygosity per population ranged from 0.18 to 0.92. Twenty of the markers conformed to Hardy–Weinberg and linkage equilibrium expectations. Most markers were easily amplified and highly reliable when analysed from buccal swabs and plucked feathers, showing that buccal swabbing is a very efficient approach allowing good quality DNA retrieval. Although DNA amplification success using single shed feathers was generally high, the genotypes obtained from this type of samples were prone to error and thus need to be amplified several times. The set of microsatellite markers described here together with multiplex amplification conditions and genotyping error rates will be useful for population genetic studies of the Ivory gull.

Stage‐dependent and sex‐dependent sensitivity to water‐soluble fractions of fresh and weathered oil in the marine copepod Calanus finmarchicus

Acute toxicity differs between species but also varies within a species. Important intraspecific factors are the exposure duration and properties of the animal such as life stage, sex, and physiological status. In the present study, the acute toxicity of water-soluble fractions (WSFs) from fresh and artificially weathered oil was followed over time in different life stages of the calanoid copepod Calanus finmarchicus, including adult males and females. The life stages differ in size but also in lipid content and physiology. To meaningfully compare the sensitivity of the different stages, the authors fitted a toxicokinetic-toxicodynamic (TKTD) model from the framework of the General Unified Threshold Model of Survival (GUTS) to the mortality patterns over time. The oil WSFs could not be treated as single compounds: the rapid effect at high doses could not be reconciled with the slow effect at low doses. Treating the oil as a mixture of 2 component blocks could, however, capture these patterns satisfactorily. Even though the early life stages of animals are generally considered to be the most vulnerable, the adult males of C. finmarchicus turned out to be most sensitive, followed by the early copepodites. Naupliar larvae were equally susceptible to oil toxicity as late copepodites and adult females. The relationship between the GUTS model parameters and the physiological traits for the different life stages remains, however, unclear.

Sublethal exposure to crude oil enhances positive phototaxis in the calanoid copepod Calanus finmarchicus.

We investigated the effects of exposure to sublethal concentrations of the water accommodated fraction (WAF) of fresh crude oil on phototactic behavior of the calanoid copepod Calanus finmarchicus (Gunnerus) copepodite stage 5 (C5). Exposure was conducted in closed bottle systems, and behavior was tested in a tailored setup. Exposure times were 24, 48, 72, and 96 h, and the chosen exposure concentration was 25% of the recorded LC50 value for the WAF (309 ± 32 μg/L total hydrocarbon, including 20.37 ± 0.51 μg/L total PAH). The exposure significantly increased the positive phototactic behavior of the copepods after 24 h exposure and a similar significant effect was observed for all exposure durations. Additionally, experiments were conducted with nonexposed copepods with low lipid reserves. The main effect of the exposure was a shift in the response to light toward a more positive phototaxis, similar to that observed in nonexposed C. finmarchicus with low lipid reserves. The observed change in phototactic behavior observed in these studies suggests that the depth distribution of this species could be altered following an oil spill. Thus, further research is warranted to determine the possible interactive effects of light and oil spill exposures on Calanus population dynamics under field conditions.