Genetic studies are widely used today to es-tablish the extent of contact between sub-populations. We have been involved in a few studies using genetics to separate stocks deal-Belugas
Innes et al. (2003) used OHC analyses to detect differences between beluga whales from Can-ada and West Greenland. Beluga caught by hunters from various hamlets in the Arctic dif-fered in the concentrations of organochlorine contaminants in their blubber. By applying Canonical Discriminant Analysis (CDA) it was possible to separate all seven sampling loca-tions from each other. The analysis provided evidence that most beluga caught by hunters from Grise Fiord, Canada were not the same as beluga caught while migrating along West Greenland. But as previously outlined, these results are at variation with those from the more direct investigations using satellite te-lemetry (Heide-Jørgensen et al. 2003a). The samples for OHC analyses in Grise Fiord (1984:
n=15; 1985: n=5; 1987: n=8) could have been too few and by chance only represented ani-mals wintering in the North Water (see also Richard et al. 1998b). All compared areas were not sampled in the same year, therefore chang-es over time in OHC levels may also have af-fected the results of the comparison. The Disko belugas were samples in 1992, whereas the Upernavik and Grise Fiord beluga samples were from 1985–1990 and 1984–1987 (Innes et al. 2002). Whether a year-to-year alternation might exist in the choice of wintering area, i.e.
North Water vs. Central West Greenland is uncertain, but according to O’Corry-Crowe et al. (2002) monodontiids have an extreme site fi delity to their selected summering and win-tering grounds in the Arctic.
Minke whales
Detection of possible stock relations among minke whales from North Atlantic minke whales has proved particularly challenging.
Only limited results from satellite telemetry have been obtained for this species, so the best information available to date is based on a large number of analysis from minke whales hunted in Greenlandic and Norwegian li-censed whaling operations over a relatively short time period from 6 May to 31 October 1998. These analyses included contaminants that were used to detect possible stock differ-ences and similarities among minke whales from seven North Atlantic IWC management areas. Overall, the seasonal and spatial
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82 Contaminants in Marine Mammals in Greenland
ties between the populations were detected, the results agreed with the contaminant stud-ies conducted by Dietz et al. (Paper 19). Stable isotope δ15N values were signifi cantly higher in samples from Uummannaq in 1993 com-pared to samples from Avanersuaq in 1984 and 1985, indicating that the narwhals in Uum-mannaq were feeding at a higher trophic level (Paper 19). However, a difference in trophic feeding level over an 8-year period could eas-ily take place, even if narwhals from Avaner-suaq are connected to those at Uummannaq.
Belugas
In an overview study of genetic relationships of Canadian and adjacent stocks of beluga whales by de March et al. (2002), it was shown that belugas from Lancaster Sound were sig-nifi cantly different from those caught in West Greenland (Upernavik and Disko Bay) based on mitochondrial DNA haplotype distribu-tion. This fi nding agrees with the OHC stud-ies of Innes et al. (2002) but contradicts the evidence collected by satellite tracking of known individuals moving between the two areas (Heide-Jørgen et al. 2003a). An overall genetic difference was also reported for belu-gas between Creswell Bay and West Green-land in 1996, where the beluga that moved from Creswell Bay to West Greenland was in-cluded in the genetic analysis reported by de
March et al. (2002). Whilst no difference was found for samples taken in Creswell Bay in 1993, un-fortunately no whales were tagged in that year.
In both 1996 and 2001, the satellite tagged whales visited several West Greenland beluga hunting grounds. These results document that genetic sampling can show varia-ble answers dependent on the sampling year, which is also the case for satellite telemetry (Heide-Jør-gensen et al. 2003a).
ing with narwhals, minke whales and ringed seals (Palsbøll et al. 1997, Andersen et al. 2003, Rew et al. in press), which are some of the key species in our and the AMAP contaminant programmes.
Narwhals
Based on mtDNA, Palsbøll et al. (1997) detect-ed fi ve sub-populations of narwhal from Northern Baffi n Bay, Eastern Greenland, Uum-mannaq district, the 1994 sassat at Kitsissuar-suit and the remaining western Greenland lo-calities including Melville Bay, Upernavik dis-trict & Disko Bay, except for the 1994 sassat samples. A later study comparing eight areas/
years with a larger sample size documented the same general pattern but also added more details (Riget et al. 2002). As satellite tracking of narwhals from Inglefi eld Bredning has only resulted in short-term results (Heide-Jørgensen unpublished), genetics and telemetry cannot be compared from this region. The genetic comparisons in mtDNA between a sample from Avanersuaq and Uummannaq narwhals showed signifi cant differences in the compari-son carried out by Palsbøll (1997), but using a larger volume of material and splitting up the sample years from Avanersuaq into two peri-ods a connection was shown between these populations in one of two comparisons (Riget et al. 2002). In the comparisons where
similari-Photo 13. Samples from too few pods may effect the answers to stock discrimina-tion. Photo: R. Dietz.
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ated minke whale sub-populations: West Greenland, Central North Atlantic-East Greenland-Jan Mayen area, NE Atlantic (Svalbard, the Barents Sea and northwestern Norway), and the North Sea. The genetic four region pattern was detected in a heavy metal study by Born et al. (2003) and a multi-ele-ment study Born et al. (2007). Comparisons of OHCs and fatty acids suggested a three re-gion model where the North Sea and Jan Mayen differed respectively (Hobbs et al.
2003, Møller et al. 2003), whereas 137Cs and stable isotopes showed other patterns (Born et al. 2002b, 2003).
Part conclusion genetics, stable isotopes and fatty acids
Genetics provide the strongest supplementary dis-cipline to satellite tagging of animals for obtaining information on population differences. However, results of both techniques are dependent on sample size and methods. Other markers, such as stable isotopes and fatty acids can be used to understand feeding behaviour and link these to contaminant loads but can also provide supplementary infor-mation on stock structures.
Monodontiid sampling
The results above bring into question how clearly genetic studies can discriminate be-tween stocks of narwhals and belugas col-lected from the hunt. Palsbøll et al. (2002) suggested that, due to the nature of the ge-netic sampling programs, gege-netic studies are more likely to discriminate pods of related whales, rather than stocks in different areas.
The samples for genetic studies are often col-lected from harvest events, where whales from the same pod are killed. Consequently, there is a high risk of obtaining samples from related individuals. This same sampling bias may be true for whales from satellite-tagging studies at a specifi c site; however, in many harvest situations, entire pods of a single fa-mily unit are sampled for genetic studies, which results in a higher degree of interrela-tedness than individual whales that are live captured over a period of days in estuaries.
For this reason there is a need to conduct ge-netic analyses on the same animals as are tracked by telemetry, so that movements and genetics can be compared directly and so that family relations in group sampling and mi-gration patters can be compared.
Ringed seals
Rew et al. (in press) detected no signifi cant levels of genetic heterogeneity among ringed seals from Avanersuaq, Upernavik and Kan-gaatsiaq (Northwest Greenland) and Dan-markshavn and Kong Oscars Fjord (North-east Greenland). Nanortalik ringed seals showed genetic differences to Northwest and Northeast Greenland seal, whereas Northeast Greenland and Svalbard were similar. Diver-gence was also observed between Northwest and Northeast Greenland. These results doc-ument that year-round open water and all-year solid ice cover reduces connectivity among seal populations. These existing barri-ers are likely to change as a result of climatic change (Rew et al. in press).
Minke whales
A study by Andersen et al. (2003) document-ed the existence of four genetically
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Photo: R. Dietz
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Conclusions 3
etz
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86 Contaminants in Marine Mammals in Greenland
tic marine food chain. Differences in trophic level of food, and possible im-pacts of climatic variability and change are important information that, if possi-ble, should be taken into account in geo-graphical and temporal trend compari-sons and future predictions.
(iii) Geographical patterns can be detected in con-taminant concentrations within Greenlandic and other Arctic marine mammal popula-tions, refl ecting regional loading of the sys-tems.
(iii) Clear geographical trends in contami-nants can be detected within the Arctic.
Northwest Greenland and the central Ca-nadian Arctic have the highest concentra-tions of Hg, Central West Greenland and Northwest Greenland have the highest concentrations of Cd, while East Green-land together with Svalbard and Kara Sea have the highest levels of most lipophilic OHCs. This information can be used to identify maximum human exposure, where possible biological effects due to high levels of contaminants are most like-ly to occur, and where the lowest exposed animals can be obtained as reference groups.
(iv) Temporal trends in contaminant levels can be detected for key species in the Greenland eco-system, refl ecting global trends in emissions and pathways.
(iv) Investigations of animal hard tissue and other long-term environmental archives have revealed long-term increases of Hg with a substantial anthropogenic contri-bution. East of Greenland this increase levelled-off somewhere around the 1960s-1970s, followed by signifi cant declines. In West Greenland, Hg increased through-out the 20th century but detailled infor-mation concerning trends during recent decades is sparse. Some West Greenland time series, as well as Central Canadian Arctic time-series indicate a continued in-crease of Hg.
The present study has documented contami-nant exposure within the Greenland ecosys-tem. Suggested conclusions to the seven the-sis points claimed in the introduction are as follows:
(i) Basic parameters such as age and sex of the animal, tissue type, and season of collection, are likely to affect contaminant concentra-tions in biota.
(i) Older animals tend to have higher con-centrations of Hg and Cd than younger animals in the Greenland marine ecosys-tem. In some cases the increase with age levels-off in old animals and for Cd in liver and kidney a decrease relative to the maximum level may be seen in old ani-mals. Differences among sexes are sel-dom recorded for Hg and Cd. Although not consistent among all species, OHC groups or studies, adult males tend to have higher concentrations of OHCs than juvenile and adult females in the Green-land marine ecosystem. In mammals, fat soluble contaminants can be transferred from females to offspring through gesta-tion and lactagesta-tion, giving mature females a mechanism for excreting these com-pounds and thereby reducing their body burden. Mercury concentrations are high-est in liver, Cd is highhigh-est in kidney and OHCs are highest in adipose or liver. The dynamics behind the pathways and accu-mulation of contaminants are complex and may be driven by many processes.
Seasonal differences should, if possible, be taken into account in geographical and temporal trend comparisons.
(ii) Ecosystem structure, differences in trophic level, biomagnifi cation characteristics, and climatic differences will have an affect on con-taminant concentrations in biota.
(ii) Due to the longer food chains and hence higher trophic levels of most marine top predators, Hg, Cd and OHC loads in these species are higher than those found in terrestrial ecosystems. Clear biomagni-fi cations are observed for Hg, OHCs and to certain extent Cd throughout the
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have been introduced at the national and in-ternational level. Most of the time-series based on contaminants analyses in soft tissue however, currently still include too few sam-pling years to provide a clear picture of inter-annual variation, and onset- and end of the relative change over time. Some highly rele-vant sample matrices, including polar bear samples available for the east coast of Green-land provide the potential for a high resolu-tion insight into trends over the time period from 1983 until today, with sampling contin-uing.
(v) The most highly exposed groups in the Arctic system, i.e. top predators, may be affected by contaminants, however even well defi ned and examined epidemiologic disease outbreaks such as PDV can be hard to link to contami-nant levels due to confounding parameters.
The best available time series for “legacy OHCs” such as PCBs, DDTs, HCHs, HCB, chlordanes, dieldrin, and coplanar PCBs show a decline in levels of these contami-nants. Time-series on toxaphene, PCDDs and PCDFs are more uncertain, but may be de-creasing. Increases in concentrations of a number of “new” OHCs such as the PBDEs and the PFCs took place prior to the turn of the millennium in the entire Arctic. PFCs con-tinue to increase in Greenland, but there is some evidence that PFCs and PBDEs over re-cent years this trend may have decreased or reversed in some areas.
The Greenland results are, in most cases consistent with longer time-series from other parts of the Arctic, but with a delay relative to the trends observed in Northern Europe. The observed trends show a response to regula-tions restricting the use of chemicals, which
Photo 14. Increased OHC concentrations have been linked to reduced size in both male an female polar bear reproductive organs. Photo: R. Dietz.
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88 Contaminants in Marine Mammals in Greenland
However, this was not the case for immu-nological organs such as lymph nodes, spleen, thymus and thyroid tissue. How-ever, no relationship was found between skull pathology and organohalogens.
Fluctuating asymmetry in polar bears showed variable results dependant on the analyhical method used. Some of the lacking skeletal effects were probably due to subeffect exposure to OHCs, infl uence of nutritional status, genetic factors or other confounding environmental factors such as climate change. A daily intake of amounts of 50–200 g marine mammal blubber from Greenland may cause an impairment of the immune system in top predators.
For well-defined mass mortality events, such as the two PDV outbreaks, where considerable effort was expended on the detection of deaths and investigation of possible population effects, it has not been possible to establish any clear linkage between contaminants, immuno-suppres-sion and number of deaths caused by the disease. A large number of confounding factors play a major role in such disease (v) Epidemiological studies on Arctic human
populations indicate neuropsychological dysfunction in some humans that resem-ble effects seen in experimental animals.
The fi rst histopathological and neuro-chemical receptor biomarkers investiga-tions indicated that effects of Hg can not be excluded. Cardiovascular and maybe other effects of Hg at higher trophic levels may be reduced and in some cases elimi-nated by the protective effect of Se, which is present in surplus in the Arctic marine ecosystem. Although Cd concentrations in several marine species are above thresh-old effect levels, Cd has not so far been proven to cause effects in Arctic wildlife.
Reduced size of reproductive organs was found for both male and female po-lar bears in relation to increased OHC concentrations. However, previous ob-servation on pseudohermaphroditism in female polar bears from Svalbard could not be verifi ed from examination of a sin-gle animal from Greenland that was found with an enlarged clitoris. Tissue al-terations were found in liver and kidney that could be linked to certain OHCs.
Photo 15. Satellite telemetry work have identifi ed polar bear population throughout the Arctic. Photo: R. Dietz.
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Other species like ringed seal have only been studied in Northwest Greenland, whereas other toothed whales and beard-ed seals have yet to be studibeard-ed.
In some regions outside Greenland, contaminant samples and samples for bi-ological effect parameters can only be ob-tained during tagging operations. Satel-lite tagging and contaminant analysis from the same animals has the potential for linking contaminant levels with dis-persal, behaviour and possible effects on the tagged animals. In cases where tag-ging has proven diffi cult to conduct, ge-netic studies on hunted animals or using biopsies represents the best supplemen-tary discipline to satellite tagging for re-solving population relationships. Con-taminants have also been used elucidate population relationships. Other disci-plines such as stable isotopes and fatty acids may be used to provide supplemen-tary information on stock structures, in addition to information to understand feeding behaviour and explain and nor-malize contaminant loads.
events. The epidemiology of PDV in Euro-pean seals showed that previous contact to PDV, local population growth rates, meta-population structure, and seasonality of the infection has a major infl uence on the de-gree of spread of the pathogen.
(vi) The Inuit population can reduce their con-taminant intake by following food recom-mendations and thereby reduce their risk of being affected by contaminants.
(vi) The Inuit population can minimize their contaminants intake and risk of health problems by reducing their intake of in-ternal organs (Hg, Cd and PFCs), fatty tis-sue (OHCs) and preferentially eating low trophic species. Intake of young animals will result in lower Cd and Hg and OHC exposure. For OHCs, consumption of adult female animals may result in lower intakes compared to consumption of adult males. International legislation and changes in anthropogenic processes are beginning to reduce the unintended trans-boundary exposure of the Arctic ecosys-tem, which will result in reduced contam-inant intake of the Greenlandic and other Arctic population. At the same time, these foods are sources of important nutrients and changes in diet can bring other health risks. Food advisories should hence be developed by relevant health authorities in consultation with local people, to pre-vent that changes in diet will result in un-intentional adverse affects on health.
(vii) Population structure studies are highly rele-vant to both the conduct of contaminant monitoring and to the interpretation of infor-mation on contaminant patterns and trends in the Arctic.
(vii) Marine mammal distribution is of major importance for planning contaminant studies and ensuring the valid interpreta-tion of results of such studies. New infor-mation based on satellite telemetry is ac-cumulating for key species such as polar bear, narwhals, belugas, walrus and some baleen whales, for some regions and sea-sons in Greenlandic and adjacent waters.
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Photo: R. Dietz
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