title: Reproductive Failure in UK Harbour Porpoises Phocoena phocoena: Legacy of Pollutant Exposure?
abstract: Reproductive failure in mammals due to exposure to polychlorinated biphenyls (PCBs) can occur either through endocrine disrupting effects or via immunosuppression and increased disease risk. To investigate further, full necropsies and determination of summed 25 polychlorinated biphenyls congeners (∑PCBs lipid weight) in blubber were undertaken on 329 UK-stranded female harbour porpoises (1990-2012). In sexually mature females, 25/127 (19.7%) showed direct evidence of reproductive failure (foetal death, aborting, dystocia or stillbirth). A further 21/127 (16.5%) had infections of the reproductive tract or tumours of reproductive tract tissues that could contribute to reproductive failure. Resting mature females (non-lactating or non-pregnant) had significantly higher mean ∑PCBs (18.5 mg/kg) than both lactating (7.5 mg/kg) and pregnant females (6 mg/kg), though not significantly different to sexually immature females (14.0 mg/kg). Using multinomial logistic regression models ΣPCBs was found to be a significant predictor of mature female reproductive status, adjusting for the effects of confounding variables. Resting females were more likely to have a higher PCB burden. Health status (proxied by "trauma" or "infectious disease" causes of death) was also a significant predictor, with lactating females (i.e. who successfully reproduced) more likely to be in good health status compared to other individuals. Based on contaminant profiles (>11 mg/kg lipid), at least 29/60 (48%) of resting females had not offloaded their pollutant burden via gestation and primarily lactation. Where data were available, these non-offloading females were previously gravid, which suggests foetal or newborn mortality. Furthermore, a lower pregnancy rate of 50% was estimated for "healthy" females that died of traumatic causes of death, compared to other populations. Whether or not PCBs are part of an underlying mechanism, we used individual PCB burdens to show further evidence of reproductive failure in the North-east Atlantic harbour porpoise population, results that should inform conservation management.
authors.affiliation: Institute of Zoology, Zoological Society of London, Regent's Park, London, United Kingdom.
authors.forename: Sinéad
authors.initials: S
authors.lastname: Murphy
authors.affiliation: Centre for Environment, Fisheries and Aquaculture Science, Lowestoft, United Kingdom.
authors.forename: Jonathan L
authors.initials: JL
authors.lastname: Barber
authors.affiliation: Oceanlab, University of Aberdeen, Newburgh, Aberdeenshire, United Kingdom.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Learmonth
authors.affiliation: Oceanlab, University of Aberdeen, Newburgh, Aberdeenshire, United Kingdom.
authors.forename: Fiona L
authors.initials: FL
authors.lastname: Read
authors.affiliation: Institute of Zoology, Zoological Society of London, Regent's Park, London, United Kingdom.
authors.forename: Robert
authors.initials: R
authors.lastname: Deaville
authors.affiliation: Institute of Zoology, Zoological Society of London, Regent's Park, London, United Kingdom.
authors.forename: Matthew W
authors.initials: MW
authors.lastname: Perkins
authors.affiliation: Scottish Marine Animal Stranding Scheme, SRUC Veterinary Services Drummondhill, Inverness, United Kingdom.
authors.forename: Andrew
authors.initials: A
authors.lastname: Brownlow
authors.affiliation: Scottish Marine Animal Stranding Scheme, SRUC Veterinary Services Drummondhill, Inverness, United Kingdom.
authors.forename: Nick
authors.initials: N
authors.lastname: Davison
authors.affiliation: Marine Environmental Monitoring, Penwalk, Llechryd, Cardigan, Ceredigion, United Kingdom.
authors.forename: Rod
authors.initials: R
authors.lastname: Penrose
authors.affiliation: Oceanlab, University of Aberdeen, Newburgh, Aberdeenshire, United Kingdom.
authors.forename: Graham J
authors.initials: GJ
authors.lastname: Pierce
authors.affiliation: Institute of Zoology, Zoological Society of London, Regent's Park, London, United Kingdom; Centre for Environment, Fisheries and Aquaculture Science, Lowestoft, United Kingdom.
authors.forename: Robin J
authors.initials: RJ
authors.lastname: Law
authors.affiliation: Institute of Zoology, Zoological Society of London, Regent's Park, London, United Kingdom.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Jepson
mesh_terms: D000818:Animals; D004784:Environmental Monitoring; D005260:Female; D016015:Logistic Models; D050741:Phocoena / Q000502:physiology*; D011078:Polychlorinated Biphenyls / Q000032:analysis* / Q000633:toxicity; D011247:Pregnancy; D012098:Reproduction / Q000187:drug effects*; D006113:United Kingdom; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D014874:Water Pollutants, Chemical; D011078:Polychlorinated Biphenyls