Impaired Renal Vein Flow in Atrial Fibrillation: A Potential Risk for Renal Dysfunction.

BACKGROUND Atrial fibrillation (AF) is one of the most common heart rhythm disorders. Identification and early treatment of AF risk factors can improve mortality and morbidity rates. This study aimed to compare the renal venous stasis index (RVSI) and intra-renal venous flow (IRVF) patterns evaluated by intra-renal Doppler ultrasonography in patients with AF and sinus rhythm (SR). MATERIAL AND METHODS A total of 68 patients, 34 with AF (lasting >12 months AF) and 34 with SR (no previous diagnosis of AF and no AF attack in 24-h Holter monitoring) were included in the study. The RVSI was calculated, and the IRVF patterns were determined using intra-renal Doppler ultrasonography. High RVSI was defined as >0.12 RVSI. In addition, echocardiography and a 6-min walk test were performed. A model including diabetes mellitus, hypertension, creatine, Pro-BNP, left ventricular ejection fraction, presence of AF, and systolic pulmonary artery pressure was created to evaluate the effects of variables on high RVSI. RESULTS The RVSI value was significantly higher in patients with AF than in those with SR (P=0.004). The SR group exhibited a higher prevalence of the continuous flow pattern, which is one of the IRVF patterns (P=0.015). In contrast, the biphasic flow pattern was observed more frequently in patients with AF (P=0.003). The presence of AF was found to predict the high RVSI (P=0.002, OR=14.134, 95% CI 2.083-71.277). CONCLUSIONS The presence of AF may affect the IRVF and cause an increase in RVSI.

Effect of Smokeless Tobacco (Maras Powder) on the Epicardial Fat Thickness and Ventricular Repolarization Parameters.

Background and Objectives: Smokeless tobacco (ST) use has recently become an alternative to cigarettes, and it has been concluded that ST is at least as harmful as cigarettes. ST use is thought to play a role in the pathogenesis of arrhythmia by affecting ventricular repolarization. In this study, we aimed to examine the relationships of Maras powder (MP), one of the ST varieties, with epicardial fat thickness and new ventricular repolarization parameters, which have not previously been described. Materials and Methods: A total of 289 male individuals were included in this study between April 2022 and December 2022. Three groups, 97 MP users, 97 smokers, and 95 healthy (non-tobacco), were compared according to electrocardiographic and echocardiographic data. Electrocardiograms (ECG) were evaluated with a magnifying glass by two expert cardiologists at a speed of 50 m/s. Epicardial fat thickness (EFT) was measured by echocardiography in the parasternal short- and long-axis images. A model was created with variables that could affect epicardial fat thickness. Results: There were no differences between the groups regarding body mass index (p = 0.672) and age (p = 0.306). The low-density lipoprotein value was higher in the MP user group (p = 0.003). The QT interval was similar between groups. Tp-e (p = 0.022), cTp-e (p = 0.013), Tp-e/QT (p =0.005), and Tp-e/cQT (p = 0.012) were higher in the MP user group. While the Tp-e/QT ratio did not affect EFT, MP predicted the epicardial fat thickness (p < 0.001, B = 0.522, 95%CI 0.272-0.773). Conclusions: Maras powder may play a role in ventricular arrhythmia by affecting EFT and causing an increase in the Tp-e interval.

The antique genetic plight of the Mediterranean monk seal (Monachus monachus).

Disentangling the impact of Late Quaternary climate change from human activities can have crucial implications on the conservation of endangered species. We investigated the population genetics and demography of the Mediterranean monk seal (Monachus monachus), one of the world's most endangered marine mammals, through an unprecedented dataset encompassing historical (extinct) and extant populations from the eastern North Atlantic to the entire Mediterranean Basin. We show that Cabo Blanco (Western Sahara/Mauritania), Madeira, Western Mediterranean (historical range) and Eastern Mediterranean regions segregate into four populations. This structure is probably the consequence of recent drift, combined with long-term isolation by distance (R2 = 0.7), resulting from prevailing short-distance (less than 500 km) and infrequent long-distance dispersal (less than 1500 km). All populations (Madeira especially), show high levels of inbreeding and low levels of genetic diversity, seemingly declining since historical time, but surprisingly not being impacted by the 1997 massive die-off in Cabo Blanco. Approximate Bayesian Computation analyses support scenarios combining local extinctions and a major effective population size decline in all populations during Antiquity. Our results suggest that the early densification of human populations around the Mediterranean Basin coupled with the development of seafaring techniques were the main drivers of the decline of Mediterranean monk seals.

Effect of the number of parity on right heart chamber quantification.

INTRODUCTION: Pregnancy is a process that can cause several physiologic changes to the cardiovascular system such as ventricular hypertrophy and dilation of cardiac chambers. Although there are studies about pregnancy-related changes in echocardiographic examination; there is no data about the long-term effects of parity on these alterations. Therefore, we evaluated the long-term effect of pregnancy on right ventricular (RV) dilation and RV hypertrophy and their relation to the parity number. METHODS: This prospective study included a total of 600 women (200 consecutive women who had no parity, 200 women who had a parity number of 1 to 4 and 200 women who had a parity number of more than 4). Right chambers' measurements were compared between the groups. RESULTS: In echocardiographic analysis, RV and right atrial dimensions and areas and RV wall thickness were higher in parous women. On the other hand, RV systolic function parameters were significantly lower in parous women. These significant changes showed a gradual increase or decrease by increasing parity number. By multivariate hierarchical logistic regression analysis, the four independent factors that increased the risk of RV dilation were age (OR: 1.16 CI: 1.10-1.20), body mass index (OR: 1.05, CI: 1.02-1.08), smoking (OR: 1.87, CI: 1.28-4.02), and giving a birth (OR: 3.94 CI: 1.82-8.81). There was also independent relationship between the number of parity and RV hypertrophy even after adjustment for several confounders. CONCLUSION: Pregnancy-related physiological changes mostly resolve after delivery. This study about long-term effects of pregnancy on RV has demonstrated that there is a significant relation between the number of parity and either RV dilation or RV hypertrophy. Each parity had also additive effect on these changes.

Prognostic significance of pre-procedural prognostic nutritional index in patients with carotid artery stenting.

BACKGROUND: Inflammation and malnutrition play a critical role in the outcomes of patients undergoing carotid artery stenting (CAS). Prognostic nutritional index (PNI) is commonly utilized to evaluate the peri-operative immune-nutritional status of patients undergoing colorectal cancer surgery and is independently associated with survival. We assessed the association between immune-nutritional status, indexed by PNI, and outcomes in CAS patients. METHODS: A total of 615 patients hospitalized for CAS in a tertiary heart center were enrolled in the study. PNI was calculated using the following formula: 10× serum albumin value (g/dL) + 0.005 × total lymphocyte count in the peripheral blood (per mm3). In-hospital and 5-year outcomes (ipsilateral stroke, major stroke, transient ischemic attack, myocardial infarction, and mortality) were compared between the tertiles of PNI. RESULTS: In-hospital outcomes were similar between the groups except the increased mortality in decreasing tertiles of PNI. During a mean follow-up duration of 51.1 months, the lower PNI tertile was related to unfavorable outcomes. After adjusting for multi-model Cox regression analysis, PNI persisted as an independent prognostic factor for mortality and major stroke. CONCLUSION: PNI was independently associated with long-term mortality and major stroke in CAS patients. Malnutrition and inflammation, which can be assessed easily and quickly using PNI, have an important prognostic value in the patients undergoing CAS.

History of expansion and anthropogenic collapse in a top marine predator of the Black Sea estimated from genetic data.

Two major ecological transitions marked the history of the Black Sea after the last Ice Age. The first was the postglacial transition from a brackish-water to a marine ecosystem dominated by porpoises and dolphins once this basin was reconnected back to the Mediterranean Sea (ca. 8,000 y B.P.). The second occurred during the past decades, when overfishing and hunting activities brought these predators close to extinction, having a deep impact on the structure and dynamics of the ecosystem. Estimating the extent of this decimation is essential for characterizing this ecosystem's dynamics and for formulating restoration plans. However, this extent is poorly documented in historical records. We addressed this issue for one of the main Black Sea predators, the harbor porpoise, using a population genetics approach. Analyzing its genetic diversity using an approximate Bayesian computation approach, we show that only a demographic expansion (at most 5,000 y ago) followed by a contemporaneous population collapse can explain the observed genetic data. We demonstrate that both the postglacial settlement of harbor porpoises in the Black Sea and the recent anthropogenic activities have left a clear footprint on their genetic diversity. Specifically, we infer a strong population reduction (~90%) that occurred within the past 5 decades, which can therefore clearly be related to the recent massive killing of small cetaceans and to the continuing incidental catches in commercial fisheries. Our study thus provides a quantitative assessment of these demographically catastrophic events, also showing that two separate historical events can be inferred from contemporary genetic data.

Postglacial climate changes and rise of three ecotypes of harbour porpoises, Phocoena phocoena, in western Palearctic waters.

Despite no obvious barriers to gene flow in the marine realm, environmental variation and ecological specializations can lead to genetic differentiation in highly mobile predators. Here, we investigated the genetic structure of the harbour porpoise over the entire species distribution range in western Palearctic waters. Combined analyses of 10 microsatellite loci and a 5085 base-pair portion of the mitochondrial genome revealed the existence of three ecotypes, equally divergent at the mitochondrial genome, distributed in the Black Sea (BS), the European continental shelf waters, and a previously overlooked ecotype in the upwelling zones of Iberia and Mauritania. Historical demographic inferences using approximate Bayesian computation (ABC) suggest that these ecotypes diverged during the last glacial maximum (c. 23-19 kilo-years ago, kyrbp). ABC supports the hypothesis that the BS and upwelling ecotypes share a more recent common ancestor (c. 14 kyrbp) than either does with the European continental shelf ecotype (c. 28 kyrbp), suggesting they probably descended from the extinct populations that once inhabited the Mediterranean during the glacial and post-glacial period. We showed that the two Atlantic ecotypes established a narrow admixture zone in the Bay of Biscay during the last millennium, with highly asymmetric gene flow. This study highlights the impacts that climate change may have on the distribution and speciation process in pelagic predators and shows that allopatric divergence can occur in these highly mobile species and be a source of genetic diversity.

How Scientific Are We in the Field of Cardiology?

OBJECTIVE: The current study investigated the contribution of the dissertations produced in the field of cardiology to the scientific literature and the factors affecting the publication process. METHODS: The study included 1049 cardiology dissertations archived in the national thesis center database between January 2010 and December 2017. The titles (English and Turkish), abstracts, and author names of cardiology dissertations were searched in Google Academic, TR Directory, and PubMed Central databases. In addition to their publication rates, the subject of the cardiology dissertations, the type of research, the type of institution, the academic title of the cardiology dissertation advisors, the duration of publication, the index of the published journals, and the quartile ranking of the Science Citation Index and Science Citation Index Expanded journals were examined. RESULTS: Among the reviewed 1049 cardiology dissertations 42.7% (n = 448) were published in a journal. The publication rate of cardiology dissertations among male authors was 43.5% and among female authors 40.1%. The cardiology dissertations were published at the highest rate after the 60th month. Among the published cardiology dissertations, 63.4% (n = 284) appeared in journals indexed by the Science Citation Index and Science Citation Index Expanded. There was no statistically significant relationship between the academic titles of cardiology dissertation advisors and the quartile ranking of Science Citation Index and Science Citation Index Expanded journals (P = 0.072). CONCLUSIONS: There were difficulties in transforming into a publication of dissertations in the field of cardiology to gain an academic identity. Incentives should be created to increase the desire and motivation of the residents.

Role of Malnutrition in Atrial Fibrillation: A Prospective Study including Individuals ≥ 75 Years of Age.

BACKGROUND: Atrial fibrillation (AF) is the most common rhythm disorder in the elderly. The AF can cause life-threatening thromboembolic complications. Therefore, there is a need to determine the risk factors of AF. In this study, we aimed to examine the association of markers of malnutrition with AF in individuals aged 75 years and older and to find the factors that may affect mortality. METHODS: In this prospective study, 358 consecutive individuals aged 75 years and older presenting to the cardiology outpatient clinic were included. All participants were divided into AF and sinus rhythm (SR) groups. In addition, a questionnaire and scoring system were used to assess malnutrition status. Information was obtained from all patients through outpatient clinic visits or telephone interviews for one year. Death from any cause was considered as the endpoint. RESULTS: AF was observed in 71 (19.8%) patients. Death was higher in patients with AF (p < 0.001), high CONUT score (p = 0.018), and GLIM malnutrition (p = 0.018). GLIM malnutrition caused a 2.8-fold increase in the development of AF. CONCLUSIONS: Screening for malnutrition in the elderly is essential. According to GLIM criteria, malnutrition may play a role in the development of AF and increase one-year mortality in the elderly.

Evolutionary history and seascape genomics of Harbour porpoises (Phocoena phocoena) across environmental gradients in the North Atlantic and adjacent waters.

The Harbour porpoise (Phocoena phocoena) is a highly mobile cetacean species primarily occurring in coastal and shelf waters across the Northern hemisphere. It inhabits heterogeneous seascapes broadly varying in salinity and temperature. Here, we produced 74 whole genomes at intermediate coverage to study Harbour porpoise's evolutionary history and investigate the role of local adaptation in the diversification into subspecies and populations. We identified ~6 million high quality SNPs sampled at eight localities across the North Atlantic and adjacent waters, which we used for population structure, demographic and genotype-environment association analyses. Our results suggest a genetic differentiation between three subspecies (P.p. relicta, P.p. phocoena and P.p. meridionalis), and three distinct populations within P.p. phocoena: Atlantic, Belt Sea and Proper Baltic Sea. Effective population size and Tajima's D suggest population contraction in Black Sea and Iberian porpoises, but expansion in the P.p. phocoena populations. Phylogenetic trees indicate post-glacial colonization from a southern refugium. Genotype-environment association analysis identified salinity as major driver in genomic variation and we identified candidate genes putatively underlying adaptation to different salinity. Our study highlights the value of whole genome resequencing to unravel subtle population structure in highly mobile species, shows how strong environmental gradients and local adaptation may lead to population differentiation, and how neutral and adaptive markers can give different perspectives on population subdivision. The results have great conservation implications as we found inbreeding and low genetic diversity in the endangered Black Sea subspecies and identified the critically endangered Proper Baltic Sea porpoises as a separate population.

Genetic and historic evidence for climate-driven population fragmentation in a top cetacean predator: the harbour porpoises in European water.

Recent climate change has triggered profound reorganization in northeast Atlantic ecosystems, with substantial impact on the distribution of marine assemblages from plankton to fishes. However, assessing the repercussions on apex marine predators remains a challenging issue, especially for pelagic species. In this study, we use Bayesian coalescent modelling of microsatellite variation to track the population demographic history of one of the smallest temperate cetaceans, the harbour porpoise (Phocoena phocoena) in European waters. Combining genetic inferences with palaeo-oceanographic and historical records provides strong evidence that populations of harbour porpoises have responded markedly to the recent climate-driven reorganization in the eastern North Atlantic food web. This response includes the isolation of porpoises in Iberian waters from those further north only approximately 300 years ago with a predominant northward migration, contemporaneous with the warming trend underway since the 'Little Ice Age' period and with the ongoing retreat of cold-water fishes from the Bay of Biscay. The extinction or exodus of harbour porpoises from the Mediterranean Sea (leaving an isolated relict population in the Black Sea) has lacked a coherent explanation. The present results suggest that the fragmentation of harbour distribution range in the Mediterranean Sea was triggered during the warm 'Mid-Holocene Optimum' period (approx. 5000 years ago), by the end of the post-glacial nutrient-rich 'Sapropel' conditions that prevailed before that time.

Population genetic structure of the short-beaked common dolphin from the Black Sea and the Turkish Straits System.

Our study aims to assess the population connectivity, evolutionary history, and conservation status of the short-beaked common dolphin in the Black Sea and Turkish Straits System (TSS). We also include DNA sequences from the Atlantic Ocean and the Mediterranean Sea to provide a regional perspective to our localized study. Analysis of 366 base pairs of mitochondrial DNA D-loop fragments from 37 samples collected from short-beaked common dolphins in the Black Sea, TSS, and Aegean Sea revealed 13 haplotypes, eight of which have not been previously reported. While analysis of samples archived on GenBank revealed 89 different haplotypes across the region. The haplotype network contains two main peripheral groups that include individuals from all locations. Haplotypes from the Atlantic Ocean are scattered across the network and no obvious population separation was detected. Some shared haplotypes potentially indicate multi-directional colonization events of the Mediterranean Sea from the eastern Atlantic Ocean. Moreover, some less widely distributed haplotypes suggest some level of more recent genetic connectivity through the Strait of Gibraltar and the TSS and point out the importance of these straits in the dispersal of short-beaked common dolphins. The haplotype and nucleotide diversity values were lower in the Black Sea, TSS, and western Mediterranean Sea when compared to the Atlantic Ocean, supporting the expansion of Atlantic populations into the Mediterranean and the Black Seas. Differentiation was observed between the Atlantic Ocean, and the Mediterranean Sea, TSS and the Black Sea based on Фst but not between Mediterranean and the Black Seas. For common dolphins, which have high dispersal potential, the protection of open seas and narrow seaways to enhance connectivity may be crucial.

Levels of heavy metals in some commercial fish species captured from the Black Sea and Mediterranean coast of Turkey.

The distribution of some heavy metals in the muscle tissue of Merlangius merlangus (whiting), Mullus barbatus (red mullet), Engraulis encrasicholus (anchovy) from Black and Mediterranean Seas were studied. The highest Al (95.313 microg/g dw), Mn (1.390 microg/g dw), Zn (25.416 microg/g dw) concentration was detected in E. encrasicholus from Black Sea; the highest Li (3.200 microg/g dw) concentration was detected in E. encrasicholus from Mediterranean Sea; the highest Cd (1.685 microg/g dw) concentration was detected in M. merlangus from Mediterranean Sea; the highest Ni (1.363 microg/g dw) concentration was detected in M. merlangus from Black Sea; the highest Pb (0.727 microg/g dw) concentration was detected in M. barbatus from Black Sea and the highest Cr (1.893 microg/g dw), Fe (21.901 microg/g dw) concentration was detected in M. barbatus from Mediterranean Sea.

Constructing the genetic population demography of the invasive lionfish Pterois miles in the Levant Basin, Eastern Mediterranean.

The recent invasion of the lionfish Pterois miles to the Mediterranean draws major concerns to the fate of the indigenous ecosystem, based on previous knowledge of the species' detrimental capabilities as an introduced species in the Western Atlantic Ocean. In order to determine invasive patterns in the Eastern Mediterranean, we compared the genetic divergence of two mtDNA markers, the COI and D-loop, between and within the introduced Levantine and native range Red Sea populations of the lionfish. COI region presented a remarkably shallow genealogy, and both genes have failed to show a definite geographic population structure, with non-significant AMOVA and low pairwise FST values. A shared haplotype across all localities in the D-loop provided probable confirmation for the Red Sea origin of the invasive population, and a number of introduced haplotypes indicated that the Mediterranean populations are a product of multiple invasion events. Finally, we observed large haplotype diversity in the Red Sea samples that were absent from the introduced localities, implying a possible future enforcement to the invasive genetic pool in the Mediterranean Sea.

Rise of oceanographic barriers in continuous populations of a cetacean: the genetic structure of harbour porpoises in Old World waters.

BACKGROUND: Understanding the role of seascape in shaping genetic and demographic population structure is highly challenging for marine pelagic species such as cetaceans for which there is generally little evidence of what could effectively restrict their dispersal. In the present work, we applied a combination of recent individual-based landscape genetic approaches to investigate the population genetic structure of a highly mobile extensive range cetacean, the harbour porpoise in the eastern North Atlantic, with regards to oceanographic characteristics that could constrain its dispersal. RESULTS: Analyses of 10 microsatellite loci for 752 individuals revealed that most of the sampled range in the eastern North Atlantic behaves as a 'continuous' population that widely extends over thousands of kilometres with significant isolation by distance (IBD). However, strong barriers to gene flow were detected in the south-eastern part of the range. These barriers coincided with profound changes in environmental characteristics and isolated, on a relatively small scale, porpoises from Iberian waters and on a larger scale porpoises from the Black Sea. CONCLUSION: The presence of these barriers to gene flow that coincide with profound changes in oceanographic features, together with the spatial variation in IBD strength, provide for the first time strong evidence that physical processes have a major impact on the demographic and genetic structure of a cetacean. This genetic pattern further suggests habitat-related fragmentation of the porpoise range that is likely to intensify with predicted surface ocean warming.

Comparison and origins of polycyclic aromatic hydrocarbons (PAHs) in the entrance and the exit of the Turkish Straits System (TSS).

Investigations of total petroleum hydrocarbons (TPHs) in water and polycyclic aromatic hydrocarbons (PAHs) in sediments were performed in the entrance and the exit of the Turkish Straits System (TSS) in autumn of 2016 and spring of 2017. TPH and PAH values ranged from 1.7 to 11.6 µg/l and 120 to 2912 ng/g (dw), respectively. On the basis of the given surface fluxes of the TSS, average petroleum flows were calculated as 1631 t/y from the Black Sea to the Marmara Sea and 8484 t/y from the Marmara Sea to the Aegean Sea. Pollution by PAHs ranged from relatively moderate to high. The most polluted sediments were collected from regions affected by shipping, such as Riva and Seddülbahir located at the entrance and the exit of the TSS, respectively. Moreover, origins of PAHs were determined using the ratios of PAH congeners. The main origins of PAHs were found as both pyrolytic and petrogenic at most stations.

Correction: The effects of marine traffic on the behaviour of Black Sea harbour porpoises (Phocoena phocoena relicta) within the Istanbul Strait, Turkey.

[This corrects the article DOI: 10.1371/journal.pone.0172970.].

The effects of marine traffic on the behaviour of Black Sea harbour porpoises (Phocoena phocoena relicta) within the Istanbul Strait, Turkey.

Marine traffic is threatening cetaceans on a local and global scale. The Istanbul Strait is one of the busiest waterways, with up to 2,500 vessels present daily. This is the first study to assess the magnitude of short- and long-term behavioural changes of the endangered Black Sea harbour porpoises (Phocoena phocoena relicta) in the presence of marine vessels within the Istanbul Strait. Markov chains were used to investigate the effect of vessel presence on the transition probability between behavioural states (diving, surface-feeding and travelling), and to quantify the effect on the behavioural budget and bout length (duration of time spent in a given state) of porpoises. Further, the changes on swimming directions of porpoises in relation to vessel speed and distance was investigated using generalized linear models. In vessel presence, porpoises were less likely to remain in a given behavioural state and instead more likely to switch to another state. Because of this, the bout length of all three behavioural states decreased significantly in the presence of vessels. The vessel effect was sufficiently large to alter the behavioural budget, with surface-feeding decreasing significantly in the presence of vessels. However, when taking into account the proportion of time that porpoises were exposed to vessels (i.e. 50%), the measured effect size was not large enough to significantly alter the animals' cumulative (diurnal) behavioural budget. Additionally, vessel speed and distance had a significant effect on the probability of porpoises showing a response in their swimming directions. The southern and middle sections of the Istanbul Strait, which have the heaviest marine traffic pressure, had the lowest porpoise sightings throughout the year. Conversely, northern sections that were exposed to a lesser degree of marine traffic hold the highest porpoise sightings. The effect shown in this study in combination with increasing human impacts within the northern sections should be considered carefully and species-specific conservation actions, including establishment of protected areas, should be put in place to prevent the long-term consequences of marine traffic on the Black Sea harbour porpoise population.

Is there a distinct harbor porpoise subpopulation in the Marmara Sea?

Genetic population structure of geographically isolated endangered Black Sea harbor porpoise (Phocoena phocoena relicta) is little known in Turkish waters, especially in the Turkish Straits System (TSS- Marmara Sea, Bosphorus and Dardanelles), which connects the Black Sea and the Aegean Sea. Mitochondrial DNA sequences of 70 new individuals sampled in the Turkish Black Sea, TSS and Aegean Sea, revealed five new haplotypes from the Black Sea. The findings support the idea that harbor porpoises from the Black Sea dispersed into the Aegean through the TSS. Considering signatures of population expansion, all subpopulations showed a signature of population expansion. The network data and the Фst calculations indicated that the Marmara Sea subpopulation was significantly differentiated from all of the other subpopulations, and supports the notion of its isolated. The finding of a potential management unit (MU) within an already heavily impacted subpopulation as a whole suggests that the individuals of P. p. relicta inhabiting the Marmara Sea require a very rigorous conservation strategy to ensure the survival of this subpopulation, represented by its unique haplotype.

Spatially Explicit Analysis of Genome-Wide SNPs Detects Subtle Population Structure in a Mobile Marine Mammal, the Harbor Porpoise.

The population structure of the highly mobile marine mammal, the harbor porpoise (Phocoena phocoena), in the Atlantic shelf waters follows a pattern of significant isolation-by-distance. The population structure of harbor porpoises from the Baltic Sea, which is connected with the North Sea through a series of basins separated by shallow underwater ridges, however, is more complex. Here, we investigated the population differentiation of harbor porpoises in European Seas with a special focus on the Baltic Sea and adjacent waters, using a population genomics approach. We used 2872 single nucleotide polymorphisms (SNPs), derived from double digest restriction-site associated DNA sequencing (ddRAD-seq), as well as 13 microsatellite loci and mitochondrial haplotypes for the same set of individuals. Spatial principal components analysis (sPCA), and Bayesian clustering on a subset of SNPs suggest three main groupings at the level of all studied regions: the Black Sea, the North Atlantic, and the Baltic Sea. Furthermore, we observed a distinct separation of the North Sea harbor porpoises from the Baltic Sea populations, and identified splits between porpoise populations within the Baltic Sea. We observed a notable distinction between the Belt Sea and the Inner Baltic Sea sub-regions. Improved delineation of harbor porpoise population assignments for the Baltic based on genomic evidence is important for conservation management of this endangered cetacean in threatened habitats, particularly in the Baltic Sea proper. In addition, we show that SNPs outperform microsatellite markers and demonstrate the utility of RAD-tags from a relatively small, opportunistically sampled cetacean sample set for population diversity and divergence analysis.