► Unpublished and published data were compiled for Arctic fish, birds, and mammals. ► These data were compared to available toxicological threshold limits. ► Toothed whales, polar bears, and some bird and fish species exceeded the limits. ► Increasing mercury concentrations are observed for some Arctic species. ► These exceeded thresholds and increasing Hg trends are of concern. a b s t r a c t a r t i c l e i n f o This review critically evaluates the available mercury (Hg) data in Arctic marine biota and the Inuit population against toxicity threshold values. In particular marine top predators exhibit concentrations of mercury in their tissues and organs that are believed to exceed thresholds for biological effects. Species whose concentrations exceed threshold values include the polar bears (Ursus maritimus), beluga whale (Delphinapterus leucas), pilot whale (Globicephala melas), hooded seal (Cystophora cristata), a few seabird species, and landlocked Arctic char (Salvelinus alpinus). Toothed whales appear to be one of the most vulnerable groups, with high concentrations Science of the Total Environment 443 (2013) [775][776][777][778][779][780][781][782][783][784][785][786][787][788][789][790]

Invasive plants provide ample opportunity to study evolutionary shifts that occur after introduction to novel environments. However, although genetic characters pre-dating introduction can be important determinants of later success, large-scale investigations of historical genetic structure have not been feasible. Common ragweed (Ambrosia artemisiifolia L.) is an invasive weed native to North America that is known for its allergenic pollen. Palynological records from sediment cores indicate that this species was uncommon before European colonization of North America, and ragweed populations expanded rapidly as settlers deforested the landscape on a massive scale, later becoming an aggressive invasive with populations established globally. Towards a direct comparison of genetic structure now and during intense anthropogenic disturbance of the late 19th century, we sampled 45 natural populations of common ragweed across its native range as well as historical herbarium specimens collected up to 140 years ago. Bayesian clustering analyses of 453 modern and 473 historical samples genotyped at three chloroplast spacer regions and six nuclear microsatellite loci reveal that historical ragweed's spatial genetic structure mirrors both the palaeo-record of Ambrosia pollen deposition and the historical pattern of agricultural density across the landscape. Furthermore, for unknown reasons, this spatial genetic pattern has changed substantially in the intervening years. Following on previous work relating morphology and genetic expression between plants collected from eastern North America and Western Europe, we speculate that the cluster associated with humans' rapid transformation of the landscape is a likely source of these aggressive invasive populations.

Highlights d 49 vertebrate species detected through metabarcoding of airborne eDNA from the zoo d Detections included 30 mammal, 13 bird, 4 fish, 1 amphibian, and 1 reptile species d 6 to 21 vertebrate species were detected per air filtering sample d Shorter geographical distance and higher biomass increased probability of detection

Mercury concentrations in hair from 397 Greenland polar bears (Ursusmaritimus) sampled between 1892 and 2001 were analyzed for temporal trends. In East Greenland the concentrations showed a significant (p < 0.0001, n = 27) increase of 3.1%/year in the period 1892-1973. In Northwest Greenland, a similar (p < 0.0001, n = 69) increase of 2.1%/year was found, which continued until 1991, when the most recent samples were obtained. In East Greenland, a significant (p = 0.009, n = 322) decrease of 0.8%/year was observed after 1973. Two Northwest Greenland samples from 1300 A.D. had a mean value of 0.52 mg/kg of dry weight, which can be considered as a baseline level. The Hg concentration during 1985-1991 from Northwest Greenland (mean value of 7.45 mg/kg of dry weight) was more than 14-fold higher than the assumed baseline level from 1300 A.D. from the same region (i.e., about 93% anthropogenic). Although a decrease was found in East Greenland after 1973, the concentration is still ca. 11-fold higher than the baseline level (i.e., about 90% anthropogenic).

Identification of populations and management units is an essential step in the study of natural systems. Still, there is limited consensus regarding how to define populations and management units, and whether genetic methods allow for inference at the relevant spatial and temporal scale. Here, we present a novel approach, integrating genetic, life history and demographic data to identify populations and management units in southern Scandinavian harbour seals. First, 15 microsatellite markers and model- and distance-based genetic clustering methods were used to determine the population genetic structure in harbour seals. Second, we used harbour seal demographic and life history data to conduct population viability analyses (PVAs) in the vortex simulation model in order to determine whether the inferred genetic units could be classified as management units according to Lowe and Allendorf's (Molecular Ecology, 19, 2010, 3038) 'population viability criterion' for demographic independence. The genetic analyses revealed fine-scale population structuring in southern Scandinavian harbour seals and pointed to the existence of several genetic units. The PVAs indicated that the census population size of each of these genetic units was sufficiently large for long-term population viability, and hence that the units could be classified as demographically independent management units. Our study suggests that population genetic inference can offer the same degree of temporal and spatial resolution as 'nongenetic' methods and that the combined use of genetic data and PVAs constitutes a promising approach for delineating populations and management units.

Recent historic abundance is an elusive parameter of great importance for conserving endangered species and understanding the pre-anthropogenic state of the biosphere. The number of studies that have used population genetic theory to estimate recent historic abundance from contemporary levels of genetic diversity has grown rapidly over the last two decades. Such assessments often yield unexpectedly large estimates of historic abundance. We review the underlying theory and common practices of estimating recent historic abundance from contemporary genetic diversity, and critically evaluate the potential issues at various estimation steps. A general issue of mismatched spatio-temporal scales between the estimation itself and the objective of the estimation emerged from our assessment; genetic diversity-based estimates of recent historic abundance represent long-term averages, whereas the objective typically is an estimate of recent abundance for a specific population. Currently, the most promising approach to estimate the difference between recent historic and contemporary abundance requires that genetic data be collected from samples of similar spatial and temporal duration. Novel genome-enabled inference methods may be able to utilize additional information of dense genome-wide distributions of markers, such as of identity-by-descent tracts, to infer recent historic abundance from contemporary samples only.

Environmental changes are prominent in Arctic ecosystems, where the distribution, abundance, life history, and health of marine organisms such as the bowhead whale (Balaena mysticetus) are tightly connected to sea ice and sea temperature. However, due to logistical and other challenges of data collection in the Arctic, appropriate assessments of past, present and future effects of climate change and human activities are lacking for many Arctic species. Environmental DNA (eDNA) is emerging as a noninvasive and cost‐effective way of obtaining genetic material from the environment and has the potential to complement traditional methods for biodiversity and genetic monitoring. In this study, we investigate whether eDNA isolated from seawater samples has the capacity to capture the genetic diversity of bowhead whales in Disko Bay, West Greenland, for the implementation of long‐term genetic monitoring programs of key Arctic marine species. A total of 41 eDNA “footprint” samples were obtained from the water surface after a whale had dived and an additional 54 eDNA samples were collected along transect lines. Samples were screened for bowhead DNA using a species‐specific qPCR primer and probe assay, and a subset of 30 samples were successfully Sanger‐sequenced to generate individual mitochondrial control region haplotypes. Moreover, by shotgun sequencing ten footprint samples on an Illumina NovaSeq platform we show that footprints generally contain less than 1% endogenous DNA, resulting in partial mitochondrial genomes in four samples out of ten samples. Our findings suggest that sampling in the footprint or wake of traveling animals is a promising method for capturing the genetic diversity of bowhead whales and other marine megafauna. With optimization of sampling and target DNA sequencing for higher endogenous DNA yield, seawater eDNA samples have a large potential for implementation in the long‐term population genetic monitoring of marine megafauna in the Arctic and elsewhere.

Assessing and studying the distribution, ecology, diversity and movements of species is key in understanding environmental and anthropogenic effects on natural ecosystems. Although environmental DNA is rapidly becoming the tool of choice to assess biodiversity there are few eDNA sample types that effectively capture terrestrial vertebrate diversity and those that do can be laborious to collect, require special permits and contain PCR inhibitory substances, which can lead to detection failure. Thus there is an urgent need for novel environmental DNA approaches for efficient and cost-effective large-scale routine monitoring of terrestrial vertebrate diversity. Here we show that DNA metabarcoding of airborne environmental DNA filtered from air can be used to detect a wide range of local vertebrate taxa. We filtered air at three localities in Copenhagen Zoo, detecting mammal, bird, amphibian and reptile species present in the zoo or its immediate surroundings. Our study demonstrates that airDNA has the capacity to complement and extend existing terrestrial vertebrate monitoring methods and could form the cornerstone of programs to assess and monitor terrestrial communities, for example in future global next generation biomonitoring frameworks.