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The Otter (Lutra lutra) in Sweden: Contaminants and Health
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Environmental toxicology. Naturhistoriska riksmuseet, Swedish Museum of Natural History.
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In the 1950s the otter started to decline in numbers and distribution in Sweden and other parts of Europe. In 1972 a game law came into force, listing otter as a species that if found dead should be reported and sent to the authorities. The numbers of dead otters reported from different areas indicate population status and distribution. Between 1970 and 2012, 832 otters were sent to the authorities, the majority (66%) during the last ten years. Most were killed in traffic accidents or drowned in fishing gear. However, the main cause of the decline is believed to be environmental contaminants. Experimental data show that a PCB residue level in muscle tissue of 12 mg/kg lw causes reproductive impairment in mink (Neovison vison), suggesting reproductive problems also in the highly PCB-exposed otters in Sweden. Since the bans of PCB and DDT in the mid-1970s, concentrations of these substances in otter and fish have decreased and the otter population is increasing.

Few pathological changes in otters have been found that can be related to high contaminant concentrations. However, we found a correlation between elevated PCB concentrations and alterations in bone mineral density. No relationship was seen between DDE and bone parameters.

The decline of the otter coincided with the decline of grey seals (Halichoerus grypus) and white-tailed sea eagles (Haliaeetus albicilla) in Sweden, all showing decreased reproductive outcome. Reproductive success started to increase for all of them around 1990 and during the same period concentrations of PCB and DDE have decreased in these species.

The body condition among female otters has increased over the study period, indicating an improved health status. However, we found a high prevalence (71%) of cysts on the spermatic duct in otters collected between 1999 and 2012, possibly caused by endocrine disrupting chemicals.

Although the organochlorine concentrations in otters have decreased, otters still face many problems. New threats to the otter population in Scandinavia are the perfluorinated chemicals, including PFOS and PFOA. Results in this thesis show an increasing trend for these compounds in otters up to 2011, including some extremely high concentrations of PFOS in otters from southern Sweden.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2013. , 47 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1051
Keyword [en]
Otter (Lutra lutra), PCB, DDT, PFAAs, reproduction, bone, time trends
National Category
Developmental Biology
Research subject
Biology with specialization in Environmental Toxicology
Identifiers
URN: urn:nbn:se:uu:diva-199068ISBN: 978-91-554-8688-4 (print)OAI: oai:DiVA.org:uu-199068DiVA: diva2:619360
Public defence
2013-06-11, Lindahlsalen, Norbyvägen 18A, Uppsala, 13:00 (English)
Opponent
Supervisors
Available from: 2013-05-21 Created: 2013-05-03 Last updated: 2013-08-30Bibliographically approved
List of papers
1. The otter (Lutra lutra) in Sweden - population trends in relation to ΣDDT and total PCB concentrations during 1968-99
Open this publication in new window or tab >>The otter (Lutra lutra) in Sweden - population trends in relation to ΣDDT and total PCB concentrations during 1968-99
2001 (English)In: Environmental Pollution, ISSN 0269-7491, E-ISSN 1873-6424, Vol. 111, 457-469 p.Article in journal, Editorial material (Refereed) Published
Abstract [en]

Polychlorinated biphenyl (PCB) has been suggested as the major cause of the European otter (Lutra lutra) population decline. This study investigates temporal and geographical changes in otter numbers as well as total PCB and ΣDDT concentrations in otters and their food in diferent parts of Sweden with various pollution impacts during three decades. In Sweden, rare species belong to the State and carcasses of such specimens are sent to the authorities. Two-hundred and eight specimens have been used to investigate temporal and spatial variation in the otter populations during 1968 and 1999. One-hundred and twentyfive of them have been chemically analysed. The population trends in northern Sweden coincide with the temporal trends of the contaminants. When concentrations of PCBs decrease in the environment, otter population increases. Neither aldrin/dieldrin nor mercury pollution seem to explain why the Swedish otter populations decreased dramatically during the 1960s-1980s. In southern Sweden total PCB concentrations are still high and the indications of improvement of the population are weak.

Keyword
Population trends, Otter, PCB, DDT, Sweden
National Category
Developmental Biology
Research subject
Biology with specialization in Environmental Toxicology
Identifiers
urn:nbn:se:uu:diva-199056 (URN)10.1016/S0269-7491(00)00085-3 (DOI)000165205900013 ()
Note

Correction in: Environmental Pollution, vol. 112, issue 3, pp. 521 (2001).

ISI: 000167622400025

Available from: 2013-05-03 Created: 2013-05-03 Last updated: 2017-12-06Bibliographically approved
2. Bone mineral density in Swedish otters (Lutra lutra) in relation to PCB and DDE concentrations
Open this publication in new window or tab >>Bone mineral density in Swedish otters (Lutra lutra) in relation to PCB and DDE concentrations
2010 (English)In: Ecotoxicology and Environmental Safety, ISSN 0147-6513, E-ISSN 1090-2414, Vol. 73, no 5, 1063-1070 p.Article in journal (Refereed) Published
Abstract [en]

The aim of this study is to elucidate if DDE (dichlorodiphenyldichloroethylene) or PCB (polybrominated diphenyls), are responsible for the pathological alterations observed in Swedish otter bone tissues. Femurs from 86 male otters collected between 1832 and 2004 were measured using peripheral quantitative computed tomography (pQCT). Some otters had very high and others fairly low concentrations of OCs (ranging between 1.4-970 mg SigmaPCB/kg l.w. and 0.0-24 mg DDE/kg l.w. in muscle tissue). Positive relationships were found between three of the four cortical bone variables analysed (area, content and thickness) and SigmaPCB concentration, while no significant relationships with DDE concentration were found. None of the trabecular variables were significantly related to PCB or DDE concentration. Three of the four trabecular bone variables showed decreasing values in the beginning and increasing values at the end of period 1974-2004. No temporal trends were found for cortical bone variables. OC concentrations decreased between 1974 and 2004.

National Category
Biological Sciences
Research subject
Ecotoxicology
Identifiers
urn:nbn:se:uu:diva-130397 (URN)10.1016/j.ecoenv.2010.02.008 (DOI)000279623800048 ()20188416 (PubMedID)
Available from: 2010-09-07 Created: 2010-09-07 Last updated: 2017-12-12Bibliographically approved
3. Improved reproductive success in otters (Lutra lutra), grey seals (Halichoerus grypus) and sea eagles (Haliaeetus albicilla) from Sweden in relation to concentrations of organochlorine contaminants
Open this publication in new window or tab >>Improved reproductive success in otters (Lutra lutra), grey seals (Halichoerus grypus) and sea eagles (Haliaeetus albicilla) from Sweden in relation to concentrations of organochlorine contaminants
Show others...
2012 (English)In: Environmental Pollution, ISSN 0269-7491, E-ISSN 1873-6424, Vol. 170, 268-275 p.Article in journal (Refereed) Published
Abstract [en]

We studied indices of reproductive outcome in three aquatic species in relation to organochlorine concentrations during four decades. In female otters, the frequency of signs of reproduction increased after 1990. In grey seals, pregnancy rate increased 1990-2010 and uterine obstructions ceased after 1993. The frequency of uterine tumours was highest 1980-2000. The number of sea eagle nestlings per checked nest increased 1985-2000, while the frequency of desiccated eggs decreased. Organochlorine concentrations decreased at annual rates between 3.5 and 10.2%. The estimated mean concentration (mg/kg lw) for total-PCB decreased from 70 to 8 (otters), from 110 to 15 (seals) and from 955 to 275 (eagles). The corresponding concentrations for Sigma DDT decreased from 3.4 to 0.2 (otters), from 192 to 2.8 (seals) and from 865 to 65 (eagles). This study adds evidence to support the hypothesis that PCBs and DDTs have had strong negative effects on the reproduction and population levels of these species.

Keyword
Reproductive outcome, Otter, Grey seal, White-tailed sea eagle, Organochlorine contamination, Packed vs capillary column GC, Sweden
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-183538 (URN)10.1016/j.envpol.2012.07.017 (DOI)000308450100033 ()
Available from: 2012-12-07 Created: 2012-10-29 Last updated: 2017-12-07Bibliographically approved
4. Increasing concentrations ofperfluoroalkyl acids in Scandinavian otters (Lutra lutra) between 1972 and 2011: a new threat to the otter population?
Open this publication in new window or tab >>Increasing concentrations ofperfluoroalkyl acids in Scandinavian otters (Lutra lutra) between 1972 and 2011: a new threat to the otter population?
Show others...
2013 (English)In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 47, no 20, 11757-11765 p.Article in journal, Editorial material (Refereed) Published
Abstract [en]

Liver samples from 140 otters (Lutra lutra) from Sweden and Norway were analyzed for 10 perfluoroalkyl carboxylic acids (PFCAs; C6-C15), 4 perfluoroalkane sulfonic acids (PFSAs; C4,C6,C8,C10) and perfluorooctane sulfonamide (FOSA). Perfluorooctane sulfonic acid (PFOS) was the dominant compound accounting for approximately 80% of the fluorinated contaminants and showing concentrations up to 16 mu g/g wet weight. Perfluorononanoic acid (PFNA) was the dominant PFCA (up to 640 ng/g wet weight) closely followed by the C10 and C11 homologues. A spatial comparison between otters from southwestern Norway, southern and northern Sweden sampled between 2005 and 2011 revealed that the samples from southern Sweden had generally the largest contaminant load, but two PFCAs and FOSA were higher concentrated in the Norwegian samples. A temporal trend study was performed on otters from southern Sweden collected between 1972 and 2011. Seven PFCAs (C8-C14), PFOS and perfluorodecane sulfonic acid (PFDS) showed significantly increasing trends with doubling times between 5.5 and 13 years. The PFCAs also showed significantly increasing trends over the period 2002 to 2011. These findings together with the exceptionally high liver concentrations of PFOS are of great concern for the Scandinavian otter populations.

Keyword
Perfluoroalkyl acids; otters (Lutra lutra); time trends; Sweden; Norway; PFOS
National Category
Developmental Biology
Research subject
Biology with specialization in Environmental Toxicology
Identifiers
urn:nbn:se:uu:diva-199063 (URN)10.1021/es401485t (DOI)000326123600050 ()
Available from: 2013-05-03 Created: 2013-05-03 Last updated: 2017-12-06Bibliographically approved
5. High prevalence of Müllerian duct remnant cysts on the spermatic duct in wild Eurasian otters (Lutra lutra) from Sweden
Open this publication in new window or tab >>High prevalence of Müllerian duct remnant cysts on the spermatic duct in wild Eurasian otters (Lutra lutra) from Sweden
2013 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 12, e84660- p.Article in journal (Refereed) Published
Abstract [en]

The spermatic ducts (vasa deferentia) of 235 otters (Lutra lutra) found dead between 1999 and 2012 in Sweden were examined for presence of paraductular cysts. Single or multiple elongated uni- or bilateral cysts parallel to the spermatic duct were noted in 72% of the examined males. The cysts were adjacent to, but did not communicate with the lumen of the spermatic duct, and were usually located within a few centimeters of the testis and epididymis. The cysts are proposed to be congenital Mullerian duct remnants. Other morphologic abnormalities in the reproductive organs were not noted within this study. Possible causes of the incomplete regression of the embryonic female gonadal duct are exposure to environmental contaminants such as elevated concentrations of estrogen-like compounds (endocrine disrupting chemicals), inbreeding, or a naturally occurring anatomic defect. No obvious geographical pattern was observed for otters with or without cysts. This is the first study and description of cysts on the spermatic duct in otters.

Keyword
Otter, Müllerian duct remnant, endocrine disrupting chemicals, Sweden
National Category
Developmental Biology
Research subject
Biology with specialization in Environmental Toxicology
Identifiers
urn:nbn:se:uu:diva-199054 (URN)10.1371/journal.pone.0084660 (DOI)000328882000157 ()
Available from: 2013-05-03 Created: 2013-05-03 Last updated: 2017-12-06Bibliographically approved

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