Population genomics of the white-beaked dolphin (Lagenorhynchus albirostris): Implications for conservation amid climate-driven range shifts.

Climate change is rapidly affecting species distributions across the globe, particularly in the North Atlantic. For highly mobile and elusive cetaceans, the genetic data needed to understand population dynamics are often scarce. Cold-water obligate species such as the white-beaked dolphin (Lagenorhynchus albirostris) face pressures from habitat shifts due to rising sea surface temperatures in addition to other direct anthropogenic threats. Unravelling the genetic connectivity between white-beaked dolphins across their range is needed to understand the extent to which climate change and anthropogenic pressures may impact species-wide genetic diversity and identify ways to protect remaining habitat. We address this by performing a population genomic assessment of white-beaked dolphins using samples from much of their contemporary range. We show that the species displays significant population structure across the North Atlantic at multiple scales. Analysis of contemporary migration rates suggests a remarkably high connectivity between populations in the western North Atlantic, Iceland and the Barents Sea, while two regional populations in the North Sea and adjacent UK and Irish waters are highly differentiated from all other clades. Our results have important implications for the conservation of white-beaked dolphins by providing guidance for the delineation of more appropriate management units and highlighting the risk that local extirpation may have on species-wide genetic diversity. In a broader context, this study highlights the importance of understanding genetic structure of all species threatened with climate change-driven range shifts to assess the risk of loss of species-wide genetic diversity.

Northerly range expansion and first confirmed records of the smalltooth sand tiger shark, Odontaspis ferox, in the United Kingdom and Ireland.

Three Odontaspis ferox (confirmed by mtDNA barcoding) were found in the English Channel and Celtic Sea in 2023 at Lepe, UK (50.7846, -1.3508), Kilmore Quay, Ireland (52.1714, -6.5937), and Lyme Bay, UK (50.6448, -2.9302). These are the first records of O. ferox in either country, and extend the species' range by over three degrees of latitude, to >52° N. They were ~275 (female), 433 (female), and 293 cm (male) total length, respectively. These continue a series of new records, possibly indicative of a climate change-induced shift in the species' range.

Postglacial Colonization of Northern Coastal Habitat by Bottlenose Dolphins: A Marine Leading-Edge Expansion?

Oscillations in the Earth's temperature and the subsequent retreating and advancing of ice-sheets around the polar regions are thought to have played an important role in shaping the distribution and genetic structuring of contemporary high-latitude populations. After the Last Glacial Maximum (LGM), retreating of the ice-sheets would have enabled early colonizers to rapidly occupy suitable niches to the exclusion of other conspecifics, thereby reducing genetic diversity at the leading-edge. Bottlenose dolphins (genus Tursiops) form distinct coastal and pelagic ecotypes, with finer-scale genetic structuring observed within each ecotype. We reconstruct the postglacial colonization of the Northeast Atlantic (NEA) by bottlenose dolphins using habitat modeling and phylogenetics. The AquaMaps model hindcasted suitable habitat for the LGM in the Atlantic lower latitude waters and parts of the Mediterranean Sea. The time-calibrated phylogeny, constructed with 86 complete mitochondrial genomes including 30 generated for this study and created using a multispecies coalescent model, suggests that the expansion to the available coastal habitat in the NEA happened via founder events starting ~15 000 years ago (95% highest posterior density interval: 4 900-26 400). The founders of the 2 distinct coastal NEA populations comprised as few as 2 maternal lineages that originated from the pelagic population. The low effective population size and genetic diversity estimated for the shared ancestral coastal population subsequent to divergence from the pelagic source population are consistent with leading-edge expansion. These findings highlight the legacy of the Late Pleistocene glacial cycles on the genetic structuring and diversity of contemporary populations.

Vertebral column deformities in white-beaked dolphins from the eastern North Atlantic.

Five white-beaked dolphins Lagenorhynchus albirostris with outwardly vertebral kyphosis, kyphoscoliosis or lordosis were identified during a photo-identification survey of over 400 individuals (2002-2013) in Faxaflói and Skjálfandi Bays, Iceland. In addition, 3 stranding reports from Denmark, The Netherlands and the UK were analysed, providing both external observation and post mortem details of axial deviations of the vertebral column in this species. Two of the free-ranging cases and 2 of the stranded specimens appeared to have an acquired disease, either as a direct result of trauma, or indirectly from trauma/wound and subsequent infection and bony proliferation, although we were unable to specifically identify the causes. Our data represent a starting point to understand vertebral column deformations and their implications in white-beaked dolphins from the eastern North Atlantic. We recommend for future necropsy cases to conduct macro- and microscopic evaluation of muscle from both sides of the deformed region, in order to assess chronic or acute conditions related to the vertebral deformations and cause of death.

Ecological opportunities and specializations shaped genetic divergence in a highly mobile marine top predator.

Environmental conditions can shape genetic and morphological divergence. Release of new habitats during historical environmental changes was a major driver of evolutionary diversification. Here, forces shaping population structure and ecotype differentiation ('pelagic' and 'coastal') of bottlenose dolphins in the North-east Atlantic were investigated using complementary evolutionary and ecological approaches. Inference of population demographic history using approximate Bayesian computation indicated that coastal populations were likely founded by the Atlantic pelagic population after the Last Glacial Maxima probably as a result of newly available coastal ecological niches. Pelagic dolphins from the Atlantic and the Mediterranean Sea likely diverged during a period of high productivity in the Mediterranean Sea. Genetic differentiation between coastal and pelagic ecotypes may be maintained by niche specializations, as indicated by stable isotope and stomach content analyses, and social behaviour. The two ecotypes were only weakly morphologically segregated in contrast to other parts of the World Ocean. This may be linked to weak contrasts between coastal and pelagic habitats and/or a relatively recent divergence. We suggest that ecological opportunity to specialize is a major driver of genetic and morphological divergence. Combining genetic, ecological and morphological approaches is essential to understanding the population structure of mobile and cryptic species.

Habitat-driven population structure of bottlenose dolphins, Tursiops truncatus, in the North-East Atlantic.

Despite no obvious barrier to gene flow, historical environmental processes and ecological specializations can lead to genetic differentiation in highly mobile animals. Ecotypes emerged in several large mammal species as a result of niche specializations and/or social organization. In the North-West Atlantic, two distinct bottlenose dolphin (Tursiops truncatus) ecotypes (i.e. 'coastal' and 'pelagic') have been identified. Here, we investigated the genetic population structure of North-East Atlantic (NEA) bottlenose dolphins on a large scale through the analysis of 381 biopsy-sampled or stranded animals using 25 microsatellites and a 682-bp portion of the mitochondrial control region. We shed light on the likely origin of stranded animals using a carcass drift prediction model. We showed, for the first time, that coastal and pelagic bottlenose dolphins were highly differentiated in the NEA. Finer-scale population structure was found within the two groups. We suggest that distinct founding events followed by parallel adaptation may have occurred independently from a large Atlantic pelagic population in the two sides of the basin. Divergence could be maintained by philopatry possibly as a result of foraging specializations and social organization. As coastal environments are under increasing anthropogenic pressures, small and isolated populations might be at risk and require appropriate conservation policies to preserve their habitats. While genetics can be a powerful first step to delineate ecotypes in protected and difficult to access taxa, ecotype distinction should be further documented through diet studies and the examination of cranial skull features associated with feeding.

Cetacean range and climate in the eastern North Atlantic: future predictions and implications for conservation.

There is increasing evidence that the distributions of a large number of species are shifting with global climate change as they track changing surface temperatures that define their thermal niche. Modelling efforts to predict species distributions under future climates have increased with concern about the overall impact of these distribution shifts on species ecology, and especially where barriers to dispersal exist. Here we apply a bio-climatic envelope modelling technique to investigate the impacts of climate change on the geographic range of ten cetacean species in the eastern North Atlantic and to assess how such modelling can be used to inform conservation and management. The modelling process integrates elements of a species' habitat and thermal niche, and employs "hindcasting" of historical distribution changes in order to verify the accuracy of the modelled relationship between temperature and species range. If this ability is not verified, there is a risk that inappropriate or inaccurate models will be used to make future predictions of species distributions. Of the ten species investigated, we found that while the models for nine could successfully explain current spatial distribution, only four had a good ability to predict distribution changes over time in response to changes in water temperature. Applied to future climate scenarios, the four species-specific models with good predictive abilities indicated range expansion in one species and range contraction in three others, including the potential loss of up to 80% of suitable white-beaked dolphin habitat. Model predictions allow identification of affected areas and the likely time-scales over which impacts will occur. Thus, this work provides important information on both our ability to predict how individual species will respond to future climate change and the applicability of predictive distribution models as a tool to help construct viable conservation and management strategies.

Cetacean Intracytoplasmic Eosinophilic Globules: A Cytomorphological, Histological, Histochemical, Immunohistochemical, and Proteomic Characterization.

The nature, etiopathogenesis, and clinicopathologic relevance of the prevalent intracytoplasmic eosinophilic globules (IEGs) within hepatocytes of cetaceans are unknown. This study aims to evaluate the presence and characterize the IEGs in the hepatocytes of cetaceans using histochemical and immunohistochemical electron microscopy, Western blot, lectin histochemistry, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry techniques. A total of 95/115 (83%) animals (16 species) exhibited histologically evident intracytoplasmic round to oval, single to multiple, hyaline eosinophilic globules within the hepatocytes. These globules were largely PAS-positive, diastase resistant, and were immunopositive for fibrinogen (FB, 97%), albumin (Alb, 85%), and α1-antitrypsine (A1AT, 53%). The IEG positivity for FB and A1AT were correlated with live-stranding, hepatic congestion and a good nutritional status. The cetaceans lacking IEGs were consistently dead stranded and had poor body conditions. The IEGs in 36 bycaught cetaceans were, all except one, FB-positive and A1AT-negative. The IEGs exhibited morphologic and compositional variations at the ultrastructural level, suggesting various stages of development and/or etiopathogenesis(es). The glycocalyx analysis suggested an FB- and A1AT-glycosylation pattern variability between cetaceans and other animals. The proteomic analyses confirmed an association between the IEGs and acute phase proteins, suggesting a relationship between acute stress (i.e., bycatch), disease, and cellular protective mechanisms, allowing pathologists to correlate this morphological change using the acute hepatocytic cell response under certain stress conditions.

The first report of meningitis in a Greenland shark (Somniosus microcephalus).

The Greenland shark (Somniosus microcephalus) is a large species of shark found in the North Atlantic and Arctic Oceans and is believed to be the longest living vertebrate. Relatively little is known about its biology, abundance, health or diseases. In March 2022, only the third reported UK stranding of this species occurred and it was the first to undergo post-mortem examination. The animal was a sexually immature female, measuring 3.96 m in length and 285 kg in weight, and was in poor nutritional state. Gross findings included haemorrhages in the skin and soft tissues, particularly of the head, and silt in the stomach suggestive of live stranding, bilateral corneal opacity, slightly turbid cerebrospinal fluid (CSF) and patchy congestion of the brain. Histopathological findings included keratitis and anterior uveitis, fibrinonecrotic and lymphohistiocytic meningitis of the brain and proximal spinal cord and fibrinonecrotizing choroid plexitis. A near pure growth of a Vibrio organism was isolated from CSF. This is believed to be the first report of meningitis in this species.

Determination of 56 per- and polyfluoroalkyl substances in top predators and their prey from Northern Europe by LC-MS/MS.

Per- and polyfluoroalkyl substances (PFAS) are a group of emerging substances that have proved to be persistent and highly bioaccumulative. They are broadly used in various applications and are known for their long-distance migration and toxicity. In this study, 65 recent specimens of a terrestrial apex predator (Common buzzard), freshwater and marine apex predators (Eurasian otter, harbour porpoise, grey seal, harbour seal) and their potential prey (bream, roach, herring, eelpout) from northern Europe (United Kingdom, Germany, the Netherlands and Sweden) were analyzed for the presence of legacy and emerging PFAS, employing a highly sensitive liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) method. 56 compounds from 14 classes were measured; 13 perfluoroalkyl carboxylic acids (PFCAs), 7 perfluoroalkyl sulphonic acids (PFSAs), 3 perfluorooctane sulfonamides (FOSAs), 4 perfluoroalkylphosphonic acids (PFAPAs), 3 perfluoroalkylphosphinic acids (PFPi's), 5 telomer alcohols (FTOHs), 2 mono-substituted polyfluorinated phosphate esters (PAPs), 2 di-substituted polyfluorinated phosphate esters (diPAPs), 6 saturated fluorotelomer acids (FTAS), 3 unsaturated fluorotelomer acids (FTUAs), 2 N-Alkyl perfluorooctane sulfonamidoethanols (FOSEs), 3 fluorotelomer sulphonic acids (FTSAs), 2 perfluoroether carboxylic acids (PFECAs) and 1 chlorinated perfluoroether sulphonic acid (Cl-PFESA). All samples were lyophilized before analysis, in order to enhance extraction efficiency, improve the precision and achieve lower detection limits. The analytes were extracted from the dry matrices through generic methods of extraction, using an accelerated solvent extraction (ASE), followed by clean-up through solid phase extraction (SPE). Method detection limits and method quantification limits ranged from 0.02 to 1.25 ng/g wet weight (ww) and from 0.05 to 3.79 ng/g (ww), respectively. Recovery ranged from 40 to 137%. Method precision ranged from 3 to 20 %RSD. The sum of PFAS concentration in apex predators livers ranged from 0.2 to 20.2 µg/g (ww), whereas in the fish species muscle tissues it ranged from 16 to 325 ng/g (ww). All analyzed specimens were primarily contaminated with PFOS, while the three PFPi's included in this study exhibited frequency of appearance (FoA) 100 %. C9 to C13 PFCAs were found at high concentrations in apex predator livers, while the overall PFAS levels in fish fillets also exceeded ecotoxicological thresholds. The findings of our study show a clear association between the PFAS concentrations in apex predators and the geographical origin of the specimens, with samples that were collected in urban and agricultural zones being highly contaminated compared to samples from pristine or semi-pristine areas. The high variety of PFAS and the different PFAS composition in the apex predators and their prey (AP&P) samples is alarming and strengthens the importance of PFAS monitoring across the food chain.

Modular organizations of novel cetacean papillomaviruses.

The phylogenetic position of cetacean papillomaviruses (PVs: Omikron-PVs and Upsilon-PVs) varies depending on the region of the genome analysed. They cluster together with Alpha-PVs when analysing early genes and with Xi-PVs and Phi-PVs when analysing late genes. We cloned and sequenced the complete genomes of five novel PVs, sampled from genital and oesophageal lesions of free-ranging cetaceans: Delphinus delphis (DdPV1), Lagenorhynchus acutus (TtPV3 variant), and Phocoena phocoena (PphPV1, PphPV2, and PphPV3). Using Maximum Likelihood and Bayesian approaches, all cetacean PVs constituted a monophyletic group with Alpha-, Omega-, and Dyodelta-PVs as inferred from E1-E2 early genes analyses, thus matching the shared phenotype of mucosal tropism. However, cetacean PVs, with the exception of PphPV3, were the closest relatives of Xi-PVs and Phi-PVs in L2-L1 late genes analyses, isolated from cow and goat, thus reflecting the close relationship between Cetacea and Artiodactyla. Our results are compatible with a recombination between ancestral PVs infecting the Cetartiodactyla lineage. Our study supports a complex evolutionary scenario with multiple driving forces for PV diversification, possibly including recombination and also interspecies transmission.

Aspergillosis in the middle ear of a harbour porpoise (Phocoena phocoena): a case report.

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.

Juvenile harbor porpoises in the UK are exposed to a more neurotoxic mixture of polychlorinated biphenyls than adults.

Polychlorinated biphenyls (PCBs) are a group of 209 persistent and bio-accumulative toxic pollutants present as complex mixtures in human and animal tissues. Harbor porpoises accumulate some of the highest levels of PCBs because they are long-lived mammals that feed at a high trophic level. Studies typically use the sum of a suite of individual chlorobiphenyl congeners (CBs) to investigate PCBs in wildlife. However, toxic effects and thresholds of CB congeners differ, therefore population health risks of exposure may be under or over-estimated dependent on the congener profiles present. In this study, we found congener profiles varied with age, sex and location, particularly between adult females and juveniles. We found that adult females had the highest proportions of octa-chlorinated congeners whilst juveniles had the highest proportions of tri- and tetra-chlorinated congeners. This is likely to be a consequence of pollutant offloading between mothers and calves during lactation. Analysis of the individual congener toxicities found that juveniles were exposed to a more neurotoxic CB mixture at a time when they were most vulnerable to its effects. These findings are an important contribution towards our understanding of variation in congener profiles and the potential effects and threats of PCB exposure in cetaceans.

Epidemiological pattern of tattoo skin disease: a potential general health indicator for cetaceans.

The presence of tattoo skin disease (TSD) was examined in 1392 free-ranging and dead odontocetes comprising 17 species from the Americas, Europe, South Africa, New Zealand and Greenland. We investigated whether TSD prevalence varied with sex, age and health status. TSD was encountered in cetaceans from the Pacific and Atlantic Oceans as well as in those from the North, Mediterranean and Tasman Seas. No clear patterns related to geography and host phylogeny were detected, except that prevalence of TSD in juveniles and, in 2 species (dusky dolphin Lagenorhynchus obscurus and Burmeister's porpoise Phocoena spinipinnis), in adults was remarkably high in samples from Peru. Environmental factors and virus properties may be responsible for this finding. Sex did not significantly influence TSD prevalence except in the case of Peruvian P. spinipinnis. Generally, there was a pattern of TSD increase in juveniles compared to calves, attributed to the loss of maternal immunity. Also, in most samples, juveniles seemed to have a higher probability of suffering TSD than adults, presumably because more adults had acquired active immunity following infection. This holo-endemic pattern was inverted in poor health short-beaked common dolphins Delphinus delphis and harbour porpoises Phocoena phocoena from the British Isles, and in Chilean dolphins Cephalorhynchus eutropia from Patagonia, where adults showed a higher TSD prevalence than juveniles. Very large tattoos were seen in some adult odontocetes from the SE Pacific, NE Atlantic and Portugal's Sado Estuary, which suggest impaired immune response. The epidemiological pattern of TSD may be an indicator of cetacean population health.

Forensic microbiology reveals that Neisseria animaloris infections in harbour porpoises follow traumatic injuries by grey seals.

Neisseria animaloris is considered to be a commensal of the canine and feline oral cavities. It is able to cause systemic infections in animals as well as humans, usually after a biting trauma has occurred. We recovered N. animaloris from chronically inflamed bite wounds on pectoral fins and tailstocks, from lungs and other internal organs of eight harbour porpoises. Gross and histopathological evidence suggest that fatal disseminated N. animaloris infections had occurred due to traumatic injury from grey seals. We therefore conclude that these porpoises survived a grey seal predatory attack, with the bite lesions representing the subsequent portal of entry for bacteria to infect the animals causing abscesses in multiple tissues, and eventually death. We demonstrate that forensic microbiology provides a useful tool for linking a perpetrator to its victim. Moreover, N. animaloris should be added to the list of potential zoonotic bacteria following interactions with seals, as the finding of systemic transfer to the lungs and other tissues of the harbour porpoises may suggest a potential to do likewise in humans.

Hepatic DNA damage in harbour porpoises (Phocoena phocoena) stranded along the English and Welsh coastlines.

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 32 P-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.

Inter-individual differences in contamination profiles as tracer of social group association in stranded sperm whales.

Ecological and physiological factors lead to different contamination patterns in individual marine mammals. The objective of the present study was to assess whether variations in contamination profiles are indicative of social structures of young male sperm whales as they might reflect a variation in feeding preferences and/or in utilized feeding grounds. We used a total of 61 variables associated with organic compounds and trace element concentrations measured in muscle, liver, kidney and blubber gained from 24 sperm whales that stranded in the North Sea in January and February 2016. Combining contaminant and genetic data, there is evidence for at least two cohorts with different origin among these stranded sperm whales; one from the Canary Island region and one from the northern part of the Atlantic. While genetic data unravel relatedness and kinship, contamination data integrate over areas, where animals occured during their lifetime. Especially in long-lived animals with a large migratory potential, as sperm whales, contamination data may carry highly relevant information about aggregation through time and space.

Beached bachelors: An extensive study on the largest recorded sperm whale Physeter macrocephalus mortality event in the North Sea.

Between the 8th January and the 25th February 2016, the largest sperm whale Physeter macrocephalus mortality event ever recorded in the North Sea occurred with 30 sperm whales stranding in five countries within six weeks. All sperm whales were immature males. Groups were stratified by size, with the smaller animals stranding in the Netherlands, and the largest in England. The majority (n = 27) of the stranded animals were necropsied and/or sampled, allowing for an international and comprehensive investigation into this mortality event. The animals were in fair to good nutritional condition and, aside from the pathologies caused by stranding, did not exhibit significant evidence of disease or trauma. Infectious agents were found, including various parasite species, several bacterial and fungal pathogens and a novel alphaherpesvirus. In nine of the sperm whales a variety of marine litter was found. However, none of these findings were considered to have been the primary cause of the stranding event. Potential anthropogenic and environmental factors that may have caused the sperm whales to enter the North Sea were assessed. Once sperm whales enter the North Sea and head south, the water becomes progressively shallower (<40 m), making this region a global hotspot for sperm whale strandings. We conclude that the reasons for sperm whales to enter the southern North Sea are the result of complex interactions of extrinsic environmental factors. As such, these large mortality events seldom have a single ultimate cause and it is only through multidisciplinary, collaborative approaches that potentially multifactorial large-scale stranding events can be effectively investigated.

Mixing of porpoise ecotypes in southwestern UK waters revealed by genetic profiling.

Contact zones between ecotypes are windows for understanding how species may react to climate changes. Here, we analysed the fine-scale genetic and morphological variation in harbour porpoises (Phocoena phocoena) around the UK by genotyping 591 stranded animals at nine microsatellite loci. The data were integrated with a prior study to map at high resolution the contact zone between two previously identified ecotypes meeting in the northern Bay of Biscay. Clustering and spatial analyses revealed that UK porpoises are derived from two genetic pools with porpoises from the southwestern UK being genetically differentiated, and having larger body sizes compared to those of other UK areas. Southwestern UK porpoises showed admixed ancestry between southern and northern ecotypes with a contact zone extending from the northern Bay of Biscay to the Celtic Sea and Channel. Around the UK, ancestry blends from one genetic group to the other along a southwest--northeast axis, correlating with body size variation, consistent with previously reported morphological differences between the two ecotypes. We also detected isolation by distance among juveniles but not in adults, suggesting that stranded juveniles display reduced intergenerational dispersal. The fine-scale structure of this admixture zone raises the question of how it will respond to future climate change and provides a reference point for further study.

Nuclear reprocessing-related radiocarbon (14C) uptake into UK marine mammals.

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