In Four Polar Bears (Ursus Maritimus) That Swam Malnourished from East Greenland to Iceland
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Science of the Total Environment 533 (2015) 290–296 Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv Polyhalogenated compounds (PCBs, chlordanes, HCB and BFRs) in four polar bears (Ursus maritimus) that swam malnourished from East Greenland to Iceland Walter Vetter a,⁎, Vanessa Gall a, Karl Skírnisson b a University of Hohenheim, Institute of Food Chemistry, Garbenstr. 28, D-70593 Stuttgart, Germany b University of Iceland, Keldur, Institute for Experimental Pathology, IS-112 Reykjavík, Iceland HIGHLIGHTS GRAPHICAL ABSTRACT • Four polar bears swam in malnourished condition from East-Greenland to Iceland. • Organohalogen compounds (PCBs, chlor- dane, PBBs, PBDEs, HCB) were quantified. • Dec-602 was tentatively identified in all tissues and an unknown compound in liver. article info abstract Article history: Levels of organohalogen compounds (PCBs, chlordane, PBB 153, PBDEs, HCB) were determined in adipose tissue, Received 24 March 2015 liver, kidney and muscle of four polar bears which swam and/or drifted to Iceland in extremely malnourished Received in revised form 2 July 2015 condition. Since the colonization in the 9th century polar bears have been repeatedly observed in Iceland. Accepted 3 July 2015 However, in recent years three of the animals have clearly left their natural habitat in poor condition in May or Available online xxxx June, i.e. at the end of the major feeding season. The fourth bear is believed to have drifted with melting ice to Editor: D. Barcelo North-Eastern Iceland in mid-winter. The concentrations of the POPs were within the range or higher than the typical concentrations measured in polar bears from the East Greenland population. In addition to the targeted Keywords: compounds, we tentatively detected Dechlorane 602 and its potential hydrodechlorinated Cl11-metabolite in Polyhalogenated compounds all samples. Moreover, a polychlorinated compound which partly co-eluted with PCB 209 was detected in all POPs liver samples but not in adipose tissue, kidney or muscle. The mass spectrum of the potential metabolite did Dechlorane-602 not allow determining its structure. Polar bears are good swimmers and can reach Iceland from the ice edge of Unknown liver peak East Greenland within a few days. Potential reasons for the swims are briefly discussed. Polar bears © 2015 Elsevier B.V. All rights reserved. Malnorishment 1. Introduction Different persistent organic pollutants (POPs) have been detected in ⁎ Corresponding author at: University of Hohenheim, Institute of Food Chemistry fl (170b) Garbenstraße 28, 70593 Stuttgart, Germany. Arctic ora and fauna due to atmospheric long range transport from in- E-mail address: [email protected] (W. Vetter). dustrialized and agricultural areas (Jones and de Voogt, 1999). As the http://dx.doi.org/10.1016/j.scitotenv.2015.07.011 0048-9697/© 2015 Elsevier B.V. All rights reserved. W. Vetter et al. / Science of the Total Environment 533 (2015) 290–296 291 top predator of the Arctic marine food web, polar bears (Ursus 2.2. Size and condition maritimus), which feed predominantly on ringed seals (Verreault et al., 2005), have been highly exposed to such pollutants as a result of All individuals were malnourished on their arrival in Iceland. The their bioaccumulation in the food chain. The natural habitats of polar lipid content of the samples was determined by isolation of the visible bears are found throughout the ice-covered seas of the circumpolar body fat reservoir and weighing it with an accuracy of one kilogram. Arctic (Stirling and Derocher, 2012). Polar bears are not native in PB-1 (male, 22.5 years old) weighed 220 kg and had a body length of Iceland, which is located south of the Arctic Circle in the North Atlantic 209 cm. The lipid content was approximately 10% of the body weight. Ocean, between North America and Europe. Sightings of polar bears in This individual arrived in Iceland on June 3, 2008 (Fig. S1, Supporting Iceland have been documented since the 9th century: at least 500 Information), i.e. at the end of the mating season and after the annual polar bears have reached the island, including 50–60 in the 20th century seal-pup hunting period on the ice north of Iceland in late winter and (Petersen and Haraldsson, 1993). Usually these polar bears traveled before the seasonal fasting from summer to fall (Polischuk et al., with pack ice drifts towards Northwest, North and Northeast Iceland. 2002). PB-2, a 14.5 year old female (142 kg body weight, 194 cm body Some were killed on arrival, but frequently the animals disappeared length) also arrived after the mating season on June 16, 2008 (Fig. S1, when they returned back to the drift ice. Some of these accounts refer Supporting Information). The annuli pattern in the cementum layer to cadavers discovered on the shore or even remains that were found suggested that this old female had given birth to cubs on three occa- in fishing nets off the coast. sions, which had most likely been successfully raised to weaning; the Between 2008 and 2011, four polar bears left their natural distribu- cubs were born when the female was six, nine and 12 years old tion range and swam to Iceland. These individuals which most likely (Skírnisson, 2009). Furthermore, a broad dark-staining incremental originated from the East Greenland population were shot when they ar- line when the female was five year old suggested that it had spent the rived in Iceland. At the time of their arrival, the East Greenland ice edge winter in a maternity den and given birth to cubs that were not raised was only 110 to 170 km away from Iceland (Skírnisson, unpublished (Skírnisson, 2009). Despite arriving shortly after the seasonal seal- data). Polar bears are good swimmers, and are able to travel this hunting period, the female had no fat reservoir left in the body, so that distance in a few days. For instance, a satellite-tracked female polar adipose tissue could not be analyzed. Immediately after its arrival the bear was found to have swum 687 km in nine days at an average exhausted old female laid down in a colony of eider ducks close to the speed of 3 km/h (Durner et al., 2011). At such a speed, the polar bears sea shore and did not attempt to move, hunt or eat. Being close to in this study would have made the journey to Iceland in 1.5–2.4 days. death, it was shot 30 h after its arrival in Iceland. Autopsy revealed Dissections revealed the polar bears to be in very poor condition with water in the lungs (evidence of heart failure). Her condition at the unusually little, if any, lipid reservoirs left. At least two of these onset of the swim (to Iceland) remains unknown but prolonged starva- malnourished animals are believed to have left their natural habitat in tion before leaving its habitat and/or during the long stay in water prior East Greenland already in poor body condition. Depending on the time to the arrival in Iceland is regarded to have depleted all fat reserves. spent during the swim to Iceland some lipid depletion would have PB-3 was a subadult female (4.5 years old, 138 kg body weight, occurred in transit as polar bears usually do not hunt and feed in the 173 cm body length) shot in North-Eastern Iceland on January 27, open sea (Durner et al., 2011). 2010 (Fig. S1, Supporting Information). Before arriving in Iceland it is In this study we analyzed persistent organic pollutants (POPs) in believed this young female had been located close to the ice edge adipose, liver, kidney and muscle tissue of the four polar bears. Since north of Iceland. The animal is thought to have drifted, perhaps on an they had not consumed any food in Iceland we compared the POP pat- iceberg into the Gulf Stream where the ice melted whereon prevailing tern in the polar bears in order to determine whether the concentra- wind and water currents from the northeast would have aided its swim- tions and compound ratios were characteristic for polar bears already ming and drifting journey to northwest Iceland (Skírnisson and examined from the neighboring East-Greenland population. We also Sigurðardóttir, 2010). The body fat reservoir of this animal was ~6% of screened the samples for new contaminants and considered some the body weight, probably not unusual for this time of year, being a potential reasons that might have influenced the decision of the polar few months prior to the seasonal feeding on the ice. PB-4 was a sub- bears to swim away from their natural range. adult, 3.5 year old female (95 kg body weight, 193 cm body length) which was detected and shot in North-West Iceland on May 2, 2011 (Fig. S1, Supporting Information). This animal's body fat reservoir was 2. Materials and methods ~5% of its body weight. Samples of these animals were compared with those of a 6.5 year old 2.1. Arrival of polar bears in Iceland and sampling young male (260 kg body weight, 205 cm body length), killed in its natural habitat at the ice-edge north of Iceland in June 1993 and later Four polar bears (PB-1 to PB-4) were shot soon after their swim to dissected at the Institute for Experimental Pathology in Iceland. Lipid Iceland in 2008, 2010, and 2011. The polar bears were dissected and reservoir contributed ~25% to the body weight (Klobes et al., 1998). processed by specialists from the Institute for Experimental Pathology, This apparently healthy individual did not show the same degree of Reykjavík, Iceland. Samples for measurements of polyhalogenated com- malnourishment and was considered to be typical for healthy polar pounds were taken from the liver, skeletal muscles, kidney and subcuta- bears at the ice edge north of Iceland.