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One level at which persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons PAHs) can exert damage is by causing DNA strand‐breaks or nucleotide base modifications, which, if unrepaired, can lead to embryonic mutations, abnormal development and cancer. In marine ecosystems, genotoxicity is expected to be particularly strong in long‐lived apex predators due to pollutant bioaccumulation. We conducted 32P‐postlabeling analyses optimized for the detection and quantification of aromatic/hydrophobic DNA adducts in the livers of 40 sexually‐mature North Atlantic harbour porpoises (Phocoena phocoena) stranded along the English and Welsh coastlines. We examined hepatic tissue to search for inflammatory and preneoplastic lesions and examine their association with adduct levels. Adducts were found in all porpoises (mean: 17.56 ± 11.95 per 108 nucleotides), and were higher than levels reported for marine vertebrates from polluted sites. The pollutants causing the induced DNA adducts could not be further characterized. Hepatic DNA damage did not correlate with levels of blubber POP concentrations (including total polychlorinated biphenyl [PCBs], dichlorodiphenyltrichloroethane [DDT] and dieldrin); PAH concentrations were not available for the present study. However, DNA damage predicted occurrence of inflammatory and preneoplastic lesions. Further, our data showed a reduction in hepatic DNA adduct levels with age in the 40 animals examined while POP concentrations, particularly PCBs, increased with age. Using a different dataset of 145 mature male harbour porpoises confirmed that higher contaminant levels (total PCBs, DDT and dieldrin) are found in older animals. The reduction in hepatic DNA adduct levels in older animals was in accordance with other studies which show that suppression of hepatic CYP1A enzyme activity at high PCB concentrations might impact on CYP1A‐mediated DNA adduct formation of PAHs which are ubiquitous environmental pollutants and readily metabolized by CYP1A to species binding to DNA. In summary, our study shows that pollutant‐induced DNA damage is prevalent in harbour porpoises from UK waters and may lead to detectable sub‐lethal hepatic damage. Environ. Mol. Mutagen. 59:613–624, 2018. © 2018 The Authors Environmental and Molecular Mutagenesis published by Wiley Periodicals, Inc. on behalf of Environmental Mutagen Society [ABSTRACT FROM AUTHOR]

To evaluate the transfer of Sellafield-derived radiocarbon ( 14 C) to top predators in the UK marine environment, 14 C activities were examined in stranded marine mammals. All samples of harbour porpoise ( Phocoena phocoena ) obtained from the Irish Sea showed 14 C enrichment above background. Mammal samples obtained from the West of Scotland, including harbour porpoise, grey seals ( Halichoerus grypus ) and harbour seals ( Phoca vitulina ) showed 14 C enrichment but to a lesser extent. This study demonstrates, for the first time, enriched 14 C is transferred through the marine food web to apex predators as a consequence of ongoing nuclear reprocessing activities at Sellafield. Total Sellafield 14 C discharge activity 24 months prior to stranding and, in particular, distance of animal stranding site from Sellafield are significant variables affecting individual 14 C activity. 14 C activities of West of Scotland harbour porpoises suggest they did not forage in the Irish Sea prior to stranding, indicating a high foraging fidelity. [ABSTRACT FROM AUTHOR]

Ecological indicators for monitoring strategies are expected to combine three major characteristics: ecological significance, statistical credibility, and cost-effectiveness. Strategies based on stranding networks rank highly in cost-effectiveness, but their ecological significance and statistical credibility are disputed. Our present goal is to improve the value of stranding data as population indicator as part of monitoring strategies by constructing the spatial and temporal null hypothesis for strandings. The null hypothesis is defined as: small cetacean distribution and mortality are uniform in space and constant in time. We used a drift model to map stranding probabilities and predict stranding patterns of cetacean carcasses under H0 across the North Sea, the Channel and the Bay of Biscay, for the period 1990–2009. As the most common cetacean occurring in this area, we chose the harbour porpoise Phocoena phocoena for our modelling. The difference between these strandings expected under H0 and observed strandings is defined as the stranding anomaly. It constituted the stranding data series corrected for drift conditions. Seasonal decomposition of stranding anomaly suggested that drift conditions did not explain observed seasonal variations of porpoise strandings. Long-term stranding anomalies increased first in the southern North Sea, the Channel and Bay of Biscay coasts, and finally the eastern North Sea. The hypothesis of changes in porpoise distribution was consistent with local visual surveys, mostly SCANS surveys (1994 and 2005). This new indicator could be applied to cetacean populations across the world and more widely to marine megafauna. [ABSTRACT FROM AUTHOR]

Abstract: Liver butyltin concentrations (monobutyl, dibutyl and tributyltin (TBT)) in harbour porpoises (n =410) have been determined during 1992–2005, and again in 2009 following a ban on the use of tributyltin-based antifouling paints on ships. The aim was to assess the effectiveness of the regulation, which was implemented during 2003–2008. Since the ban was put in place summed butyltin concentrations have declined. Also, the percentage of animals in which TBT was detected has fallen sharply, indicating the cessation of fresh inputs. In 1992, 1993 and 1995, TBT was detected in 100% of samples analysed. In 2003–2005, once the implementation of the ban had begun, this fell to 61–72%, and in 2009, following the completion of the ban, had reduced to 4.3% (i.e. in only 1 of 23 samples analysed). Thus we conclude that the ban has proved effective in reducing TBT inputs to the seas from vessels. [Copyright &y& Elsevier]

Abstract: The associations between polychlorinated biphenyls (PCBs) exposure and involution of lymphoid tissue and development of epithelial-lined cysts in the thymus of UK-stranded harbour porpoises (Phocoena phocoena) (n =170) were tested. Percentage of thymic lymphoid tissue (%TLT) was histologically quantified. Multiple regression analyses (n =169) demonstrated significant positive correlation between %TLT and nutritional status (p <0.001) and significant negative association between %TLT and onset of sexual maturity (p <0.001). However, in a subgroup of porpoises with total PCB levels above a proposed threshold of toxicity (>17mg/kg lipid weight) (n =109), the negative association between %TLT (as dependent variable) and summed blubber concentrations of 25 chlorobiphenyl congeners (∑25CBs) remained significant (p <0.01) along with nutritional status (p <0.001) and onset of sexual maturity (p <0.001). These results suggest PCB-induced immuno suppression may be occurring in harbour porpoises in UK waters but only at concentrations that exceed proposed toxicity thresholds for marine mammals. In contrast, development of thymic cysts appears predominantly age-related. [Copyright &y& Elsevier]

Since 1990, tissue samples from UK-stranded and -bycaught cetaceans have been available for study of contaminant burdens. These have been used to study spatial and temporal trends in concentrations in UK waters, and to investigate potential associations between contaminants and health status. We describe the current status of cetaceans (primarily harbour porpoises, Phocoena phocoena ) in UK waters in relation to pollution. Concentrations of BDEs, HBCD, and the organochlorine pesticides are declining. In contrast, concentrations of CBs have plateaued following earlier reductions due to regulation of use, and further reductions are likely to take decades. Blubber PCB concentrations are still at toxicologically significant levels in many harbour porpoises and regularly occur at even higher levels in bottlenose dolphins and killer whales due to their higher trophic level in marine food chains. Further reductions in PCB inputs into the marine environment are needed to mitigate risk from PCB exposure in these species. [ABSTRACT FROM AUTHOR]

Hearing is one of the major senses in whales and dolphins (cetaceans). This is the first report of severe mycotic otitis media in a cetacean, a juvenile female harbour porpoise ( Phocoena phocoena) from British waters that stranded alive. Gross examinations were followed by histological and microbiological investigations of the auditory apparatus. Both tympanic cavities and periotic sinuses displayed copious greenish-yellow purulent and caseous material . Severe fungal infestation by Aspergillus terreus was documented in the otic region but not in any other site of the body. Adjacent to the promontorium, massive accumulation of fibrinous secretion and infiltration of clusters of inflammatory cells were present. Newly formed cysts and vessels replaced the round window membrane location, reminiscent of granulation tissue. Inflammatory cells and a severe fibrin net were noted within the perilymphatic spaces of scala tympani and scala vestibuli, indicative of an acute fibrinous otitis. Inflammatory reactions have probably been caused by this fungal organism. The basilar membrane was solely covered by a simple cuboidal epithelium. Complete absence of sensory cells of the Organ of Corti characterised a further severe phenomenon, which possibly led to the animal's poor nutritional status and stranding. Potential portals of entry are being discussed. [ABSTRACT FROM AUTHOR]

Abstract: Harbour porpoises sampled within the UK Cetacean Strandings Investigation Programme have been analysed for 25 chlorobiphenyl congeners. In all, 440 porpoises stranded or bycaught during the period 1991–2005 were studied. There are regional differences in the trend in summed congener concentrations over time but, despite controls on PCBs having been in place for decades, they are declining only slowly. Their toxic impacts in UK porpoises – increased susceptibility to infectious disease mortality in the most contaminated individuals – looks likely to continue for some time yet. Further efforts to limit or eliminate PCB discharges to the marine environment are still needed. [Copyright &y& Elsevier]

Abstract: Thirty alternative flame retardant compounds and a suite of 17 brominated diphenyl ether (BDE) congeners were determined in the blubber of 21 harbour porpoises stranded or bycaught around UK coasts during 2008 using GC-MS/MS. Of the 30 compounds, 19 were not detected. Of the remaining 11 compounds, some fell below the lowest calibration level and so were recorded as less than values, but were certainly present in the blubber samples (examples include tetrabromo-p-xylene (TBX), tetrabromo-o-chlorotoluene (TBCT) and 2,3-dibromopropyl-2,4,6-tribromophenyl ether (TBP-DBPE). Concentrations were low, the highest concentration being only 35μgkg−1 wet weight. This contrasted with those of the BDEs, summed concentrations which ranged from 54.6 to 913μgkg−1 wet weight, although levels in porpoise blubber have been declining since 1998. Both Dechlorane Plus (DDC-CO) isomers were detected in some samples, suggesting either that this product has been used in the UK or that its presence may result from atmospheric transport from source regions. BDE183, a marker for the octa-mix PBDE product, was found at low concentrations (0.63 to 1.7μgkg−1 wet weight) and the four nona- and deca-BDE congeners were not detected in any sample. [Copyright &y& Elsevier]

Controls were placed on the production and use of the pentamix polybrominated diphenyl ether (PBDE) formulation within the European Union in 2004. In porpoises stranded or bycaught around the U.K., BDE congeners from this product predominate. Lipid-normalized concentrations of 9 (summed) BDE congeners in the blubber of 415 porpoises sampled during the period 1992-2008 have been investigated for possible time trends resulting from the regulatory action. Our analysis suggests that overall, median Σ9BDE concentrations peaked around 1998 and have since reduced by between 53.8% and 73.5% to 2008. Our best point estimate is that the reduction has been 67.6%. This decline was highly statistically significant (p < 0.001) and was not confounded by a range of other factors which were also considered (area, season, nutritional status, bycaught/stranded, and age class). [ABSTRACT FROM AUTHOR]

With global increases in anthropogenic pressures on wildlife populations comes a responsibility to manage them effectively. The assessment of marine ecosystem health is challenging and often relies on monitoring indicator species, such as cetaceans. Most cetaceans are however highly mobile and spend the majority of their time hidden from direct view, resulting in uncertainty on even the most basic population metrics. Here, we discuss the value of long-term and internationally combined stranding records as a valuable source of information on the demographic and mortality trends of the harbour porpoise (Phocoena phocoena) in the North Sea. We analysed stranding records (n = 16,181) from 1990 to 2017 and demonstrate a strong heterogeneous seasonal pattern of strandings throughout the North Sea, indicative of season-specific distribution or habitat use, and season-specific mortality. The annual incidence of strandings has increased since 1990, with a notable steeper rise particularly in the southern North Sea since 2005. A high density of neonatal strandings occurred specifically in the eastern North Sea, indicative of areas important for calving, and large numbers of juvenile males stranded in the southern parts, indicative of a population sink or reflecting higher male dispersion. These findings highlight the power of stranding records to detect potentially vulnerable population groups in time and space. This knowledge is vital for managers and can guide, for example, conservation measures such as the establishment of time-area-specific limits to potentially harmful human activities, aiming to reduce the number and intensity of human-wildlife conflicts. • International data synthesis to understand wildlife mortality and demographic trends • We demonstrate the value of long-term surveillance exemplified by stranding records. • Our analyses indicate potential vulnerable population groups in time and space. • Analytical methods allow establishment of robust baseline of spatiotemporal variation. • Results guide conservation measures aiming to reduce human-wildlife conflicts at sea. [ABSTRACT FROM AUTHOR]