[Zoonotic potential of brucellosis in marine mammals]. / Potentiel zoonotique de la brucellose des mammifères marins.

Introduction: Brucellosis in marine mammals (cetacean and pinnipeds) has emerged in a very significant way during the last two decades. Currently Brucella ceti and Brucella pinnipedialis are the two recognized species in marine mammals, but available information is still limited. Several genotypes have been identified, and studies on the relationship between sequence type (ST) and organ pathogenicity or tropism have indicated differences in pathogenesis between B. ceti sequences in cetaceans. The zoonotic potential of this disease is based on the identification of the main sources of introduction and spread of Brucella spp. in the marine environment as well as on the factors of exposure of marine mammals and humans to the bacteria. Bibliographic review: This article is a bibliographical review on marine mammal brucellosis, including the features, sources and transmission modes of each Brucella species, as well as their potential pathogenicity in animals and humans. Conclusion: Different genotypes of marine Brucella spp have been isolated from marine mammal species but without any evidence of pathology induced by these bacteria. Associated lesions are variable and include subcutaneous abscesses, meningo-encephalomyelitis, pneumonia, myocarditis, osteoarthritis, orchitis, endometritis, placentitis and abortion. The isolation of marine B. spp from marine mammal respiratory parasites associated to lung injury has raised the intriguing possibility that they may serve as a vector for the transmission of this bacterium.The severity of marine B. spp remains unknown due to the lack of an estimate of the prevalence of this disease in marine mammals. The number of suspected human cases is still very limited. However, by analogy with other germs of the genus Brucella responsible for abortion in ruminants and for a febrile and painful state in human beings, prevention measures are essential. The significant increase in the number of strandings coupled with a high seroprevalence in certain species of marine mammals must be considered for people in direct or indirect contact with these animals. Ongoing epidemiological monitoring combined with extensive post-mortem examinations (necropsy, bacteriology and sequencing) of all species of stranded marine mammals would deepen knowledge on the zoonotic potential of marine Brucella species.

Tetrapod biodiversity in sambaquis from southern Brazil.

Fishermen-hunter-gatherers of sambaquis (Brazilian shell mounds) had an intimate affinity with marine-coastal environments, where they exploited a great variety of fish and mollusks that comprise the best documented fauna from sambaquis. However, other groups of animals as mammals, birds, reptiles, and amphibians are also present in these sites, but are relatively less studied. This paper is the first one focused exclusively on the Tetrapoda biodiversity of sambaquis and aimed to identify tetrapods of ten sites from southern Brazil. We present a faunal inventory and data regarding animal capture and environmental exploitation. We identified the specimens anatomically and taxonomically, analyzed them concerning fragmentation, and quantified the data for the number of identified specimens (NISP) and minimum number of individuals (MNI). Despite the high degree of fragmentation of remains, we identified 46 taxa. As expected, most were from marine animals: cetaceans (total NISP = 2,568 and MNI = 27), otariids (total NISP = 248 and MNI = 32), and seabirds (total NISP = 65 and MNI = 23), indicating great relevance of marine tetrapod fauna as a resource for sambaqui builders (79.39% of NISP). We thus document the close bond between fishermen-hunter-gatherers of sambaquis and the marine tetrapods in southern Brazil.

Meta-analysis of the Cetacea gut microbiome: Diversity, co-evolution, and interaction with the anthropogenic pathobiome.

Despite their critical roles in marine ecosystems, only few studies have addressed the gut microbiome (GM) of cetaceans in a comprehensive way. Being long-living apex predators with a carnivorous diet but evolved from herbivorous ancestors, cetaceans are an ideal model for studying GM-host evolutionary drivers of symbiosis and represent a valuable proxy of overall marine ecosystem health. Here, we investigated the GM of eight different cetacean species, including both Odontocetes (toothed whales) and Mysticetes (baleen whales), by means of 16S rRNA-targeted amplicon sequencing. We collected faecal samples from free-ranging cetaceans circulating within the Pelagos Sanctuary (North-western Mediterranean Sea) and we also included publicly available cetacean gut microbiome sequences. Overall, we show a clear GM trajectory related to host phylogeny and taxonomy (i.e., phylosymbiosis), with remarkable GM variations which may reflect adaptations to different diets between baleen and toothed whales. While most samples were found to be infected by protozoan parasites of potential anthropic origin, we report that this phenomenon did not lead to severe GM dysbiosis. This study underlines the importance of both host phylogeny and diet in shaping the GM of cetaceans, highlighting the role of neutral processes as well as environmental factors in the establishment of this GM-host symbiosis. Furthermore, the presence of potentially human-derived protozoan parasites in faeces of free-ranging cetaceans emphasizes the importance of these animals as bioindicators of anthropic impact on marine ecosystems.

Cetaceans are the next frontier for vocal rhythm research.

While rhythm can facilitate and enhance many aspects of behavior, its evolutionary trajectory in vocal communication systems remains enigmatic. We can trace evolutionary processes by investigating rhythmic abilities in different species, but research to date has largely focused on songbirds and primates. We present evidence that cetaceans-whales, dolphins, and porpoises-are a missing piece of the puzzle for understanding why rhythm evolved in vocal communication systems. Cetaceans not only produce rhythmic vocalizations but also exhibit behaviors known or thought to play a role in the evolution of different features of rhythm. These behaviors include vocal learning abilities, advanced breathing control, sexually selected vocal displays, prolonged mother-infant bonds, and behavioral synchronization. The untapped comparative potential of cetaceans is further enhanced by high interspecific diversity, which generates natural ranges of vocal and social complexity for investigating various evolutionary hypotheses. We show that rhythm (particularly isochronous rhythm, when sounds are equally spaced in time) is prevalent in cetacean vocalizations but is used in different contexts by baleen and toothed whales. We also highlight key questions and research areas that will enhance understanding of vocal rhythms across taxa. By coupling an infraorder-level taxonomic assessment of vocal rhythm production with comparisons to other species, we illustrate how broadly comparative research can contribute to a more nuanced understanding of the prevalence, evolution, and possible functions of rhythm in animal communication.

Introduction to the special issue on fish bioacoustics: Hearing and sound communicationa).

Fish bioacoustics, or the study of fish hearing, sound production, and acoustic communication, was discussed as early as Aristotle. However, questions about how fishes hear were not really addressed until the early 20th century. Work on fish bioacoustics grew after World War II and considerably in the 21st century since investigators, regulators, and others realized that anthropogenic (human-generated sounds), which had primarily been of interest to workers on marine mammals, was likely to have a major impact on fishes (as well as on aquatic invertebrates). Moreover, passive acoustic monitoring of fishes, recording fish sounds in the field, has blossomed as a noninvasive technique for sampling abundance, distribution, and reproduction of various sonic fishes. The field is vital since fishes and aquatic invertebrates make up a major portion of the protein eaten by a signification portion of humans. To help better understand fish bioacoustics and engage it with issues of anthropogenic sound, this special issue of The Journal of the Acoustical Society of America (JASA) brings together papers that explore the breadth of the topic, from a historical perspective to the latest findings on the impact of anthropogenic sounds on fishes.

Modeling the influence of bacteria concentration on the mechanical properties of self-healing concrete (SHC) for sustainable bio-concrete structures.

In this research paper, the intelligent learning abilities of the gray wolf optimization (GWO), multi-verse optimization (MVO), moth fly optimization, particle swarm optimization (PSO), and whale optimization algorithm (WOA) metaheuristic techniques and the response surface methodology (RSM) has been studied in the prediction of the mechanical properties of self-healing concrete. Bio-concrete technology stimulated by the concentration of bacteria has been utilized as a sustainable structural concrete for the future of the built environment. This is due to the recovery tendency of the concrete structures after noticeable structural failures. However, it requires a somewhat expensive exercise and technology to create the medium for the growth of the bacteria needed for this self-healing ability. The method of data gathering, analysis and intelligent prediction has been adopted to propose parametric relationships between the bacteria usage and the concrete performance in terms of strength and durability. This makes is cheaper to design self-healing concrete structures based on the optimized mathematical relationships and models proposed from this exercise. The performance of the models was tested by using the coefficient of determination (R2), root mean squared errors, mean absolute errors, mean squared errors, variance accounted for and the coefficient of error. At the end of the prediction protocol and model performance evaluation, it was found that the classified metaheuristic techniques outclassed the RSM due their ability to mimic human and animal genetics of mutation. Furthermore, it can be finally remarked that the GWO outclassed the other methods in predicting the concrete slump (Sl) with R2 of 0.998 and 0.989 for the train and test, respectively, the PSO outclassed the rest in predicting the flexural strength with R2 of 0.989 and 0.937 for train and test, respectively and the MVO outclassed the others in predicting the compressive strength with R2 of 0.998 and 0.958 for train and test, respectively.

New occurrences of the bone-eating worm Osedax from Late Cretaceous marine reptiles and implications for its biogeography and diversification.

The bone-eating worm Osedax is a speciose and globally distributed clade, primarily found on whale carcasses in marine environments. The earliest fossil evidence for Osedax borings was previously described in plesiosaur and sea turtle bones from the mid-Cretaceous of the United Kingdom, representing the only unequivocal pre-Oligocene occurrences. Confirming through CT scanning, we present new evidence of Osedax borings in three plesiosaur specimens and, for the first time, identify borings in two mosasaur specimens. All specimens are from the Late Cretaceous: one from the Cenomanian of the United Kingdom, two from the Campanian of the southeastern United States, and two from the Maastrichtian of Belgium. This extends the geographic range of Osedax in the Cretaceous to both sides of the northern Atlantic Ocean. The bones contain five borehole morphotypes, potentially created by different species of Osedax, with the Cenomanian specimen containing three morphotypes within a single tooth. This combined evidence of heightened species diversity by the Cenomanian and broad geographic range by the Campanian potentially indicates an earlier origin and diversification for this clade than previously hypothesized. Preservational biases indicate that Osedax was probably even more widely distributed and speciose in the Cretaceous than apparent in the fossil record.

Language-like efficiency and structure in house finch song.

Communication needs to be complex enough to be functional while minimizing learning and production costs. Recent work suggests that the vocalizations and gestures of some songbirds, cetaceans and great apes may conform to linguistic laws that reflect this trade-off between efficiency and complexity. In studies of non-human communication, though, clustering signals into types cannot be done a priori, and decisions about the appropriate grain of analysis may affect statistical signals in the data. The aim of this study was to assess the evidence for language-like efficiency and structure in house finch (Haemorhous mexicanus) song across three levels of granularity in syllable clustering. The results show strong evidence for Zipf's rank-frequency law, Zipf's law of abbreviation and Menzerath's law. Additional analyses show that house finch songs have small-world structure, thought to reflect systematic structure in syntax, and the mutual information decay of sequences is consistent with a combination of Markovian and hierarchical processes. These statistical patterns are robust across three levels of granularity in syllable clustering, pointing to a limited form of scale invariance. In sum, it appears that house finch song has been shaped by pressure for efficiency, possibly to offset the costs of female preferences for complexity.

Evolutionary genetics of pulmonary anatomical adaptations in deep-diving cetaceans.

BACKGROUND: Cetaceans, having experienced prolonged adaptation to aquatic environments, have undergone evolutionary changes in their respiratory systems. This process of evolution has resulted in the emergence of distinctive phenotypic traits, notably the abundance of elastic fibers and thickened alveolar walls in their lungs, which may facilitate alveolar collapse during diving. This structure helps selective exchange of oxygen and carbon dioxide, while minimizing nitrogen exchange, thereby reducing the risk of DCS. Nevertheless, the scientific inquiry into the mechanisms through which these unique phenotypic characteristics govern the diving behavior of marine mammals, including cetaceans, remains unresolved. RESULTS: This study entails an evolutionary analysis of 42 genes associated with pulmonary fibrosis across 45 mammalian species. Twenty-one genes in cetaceans exhibited accelerated evolution, featuring specific amino acid substitutions in 14 of them. Primarily linked to the development of the respiratory system and lung morphological construction, these genes play a crucial role. Moreover, among marine mammals, we identified eight genes undergoing positive selection, and the evolutionary rates of three genes significantly correlated with diving depth. Specifically, the SFTPC gene exhibited convergent amino acid substitutions. Through in vitro cellular experiments, we illustrated that convergent amino acid site mutations in SFTPC contribute positively to pulmonary fibrosis in marine mammals, and the presence of this phenotype can induce deep alveolar collapse during diving, thereby reducing the risk of DCS during diving. CONCLUSIONS: The study unveils pivotal genetic signals in cetaceans and other marine mammals, arising through evolution. These genetic signals may influence lung characteristics in marine mammals and have been linked to a reduced risk of developing DCS. Moreover, the research serves as a valuable reference for delving deeper into human diving physiology.

Effects of duty cycle on passive acoustic monitoring metrics: The case of blue whale songs.

Long-term fixed passive acoustic monitoring of cetacean populations is a logistical and technological challenge, often limited by the battery capacity of the autonomous recorders. Depending on the research scope and target species, temporal subsampling of the data may become necessary to extend the deployment period. This study explores the effects of different duty cycles on metrics that describe patterns of seasonal presence, call type richness richness, and daily call rate of three blue whale acoustics populations in the Southern Indian Ocean. Detections of blue whale calls from continuous acoustic data were subsampled with three different duty cycles of 50%, 33%, and 25% within listening periods ranging from 1 min to 6 h. Results show that reducing the percentage of recording time reduces the accuracy of the observed seasonal patterns as well as the estimation of daily call rate and call call type richness. For a specific duty cycle, short listening periods (5-30 min) are preferred to longer listening periods (1-6 h). The effects of subsampling are greater the lower the species' vocal activity or the shorter their periods of presence. These results emphasize the importance of selecting a subsampling scheme adapted to the target species.

Molecular characterization of cetacean poxviruses along the coast of mainland Portugal.

Cetacean poxvirus (CePV) is the causative agent of tattoo skin disease (TSD) in dolphins, porpoises and whales, a condition characterized by pinhole, ring-like lesions or generalized tattoo-like skin lesions. This study genetically characterized cetacean poxviruses from stranded animals along mainland Portugal. Samples from skin lesions compatible with TSD were obtained from 4 odontocete species (Delphinus delphis, Stenella coeruleoalba, Phocoena phocoena, and Tursiops truncatus) and analyzed using a conventional PCR assay targeting the DNA polymerase gene partially. Among the positive samples (n = 29, 65.9%), a larger DNA polymerase gene fragment was obtained, allowing a robust phylogenetic analysis. Nineteen samples (43.2%) were successfully amplified and sequenced using Sanger sequencing. By combining 11 of these sequences with those from public databases, a maximum likelihood phylogenetic tree was constructed, revealing high heterogeneity within the group. These findings contribute to a better understanding of the genetic diversity, epidemiology, phylogenetics, and evolution of CePV.

Localized Expression of Olfactory Receptor Genes in the Olfactory Organ of Common Minke Whales.

Baleen whales (Mysticeti) possess the necessary anatomical structures and genetic elements for olfaction. Nevertheless, the olfactory receptor gene (OR) repertoire has undergone substantial degeneration in the cetacean lineage following the divergence of the Artiodactyla and Cetacea. The functionality of highly degenerated mysticete ORs within their olfactory epithelium remains unknown. In this study, we extracted total RNA from the nasal mucosae of common minke whales (Balaenoptera acutorostrata) to investigate ORs' localized expression. All three sections of the mucosae examined in the nasal chamber displayed comparable histological structure. However, the posterior portion of the frontoturbinal region exhibited notably high OR expression. Neither the olfactory bulb nor the external skin exhibited the expression of these genes. Although this species possesses four intact non-class-2 ORs, all the ORs expressed in the nasal mucosae belong to class-2, implying the loss of aversion to specific odorants. These anatomical and genomic analyses suggest that ORs are still responsible for olfaction within the nasal region of baleen whales, enabling them to detect desirable scents such as prey and potential mating partners.

Organohalogen compounds in a hotspot for chemical pollution: Assessment in free-ranging Atlantic spotted dolphins (Stenella frontalis).

The assessment of chemical pollution in free-ranging living mammals is viable using remote biopsies and portrays a comprehensive scenario of environmental health. The Southwestern Atlantic Ocean holds incredible biodiversity, but it is under the constant and invisible threat of persistent organic pollutants (POPs) of anthropogenic origin, such as pesticides, brominated flame retardants, and industrial-use compounds (e.g., PCBs). Thus, this study aimed to assess the bioaccumulation of POPs (PCBs, DDTs, HCB, mirex and PBDEs) and natural organobromine compounds (MeO-BDEs) using gas-chromatography coupled to mass spectrometry in biopsy samples of Atlantic spotted dolphins (Stenella frontalis, n = 20) that inhabit and forage both inside and in adjacent areas to degraded (Guanabara Bay) and conserved (Ilha Grande Bay) coastal bays in the Southeastern Brazil. Among the studied compounds, PCBs were predominant in the contamination profile with median concentration of 97.0 µg.g-1 lipid weight (lw), followed by the sum of the p,p' isomers of DDT, DDD, and DDE of 11.0 µg.g-1 lw, the brominated flame retardants PBDEs of 1.6 µg.g-1 lw, and the other organochlorine pesticides mirex of 0.78 µg.g-1 lw, and HCB of 0.049 µg.g-1 lw. The MeO-BDEs were detected with a median concentration of 22.8 µg.g-1 lw. 85 % of the Atlantic spotted dolphins analyzed in this study presented PCB concentration that exceeded even the less conservative threshold limits for adverse health effects (41 µg.g-1 lw). This study shows that despite the conservation status of preserved bays, cetacean species foraging in these locations are still under increased threat. Hence chemical pollution demands local and global efforts to be mitigated.

A new strategy for groundwater level prediction using a hybrid deep learning model under Ecological Water Replenishment.

Accurate prediction of the groundwater level (GWL) is crucial for sustainable groundwater resource management. Ecological water replenishment (EWR) involves artificially diverting water to replenish the ecological flow and water resources of both surface water and groundwater within the basin. However, fluctuations in GWLs during the EWR process exhibit high nonlinearity and complexity in their time series, making it challenging for single data-driven models to predict the trend of groundwater level changes under the backdrop of EWR. This study introduced a new GWL prediction strategy based on a hybrid deep learning model, STL-IWOA-GRU. It integrated the LOESS-based seasonal trend decomposition algorithm (STL), improved whale optimization algorithm (IWOA), and Gated recurrent unit (GRU). The aim was to accurately predict GWLs in the context of EWR. This study gathered GWL, precipitation, and surface runoff data from 21 monitoring wells in the Yongding River Basin (Beijing Section) over a period of 731 days. The research results demonstrate that the improvement strategy implemented for the IWOA enhances the convergence speed and global search capabilities of the algorithm. In the case analysis, evaluation metrics including the root mean square error (RMSE), mean absolute error (MAE), mean absolute percentage error (MAPE), and Nash-Sutcliffe efficiency (NSE) were employed. STL-IWOA-GRU exhibited commendable performance, with MAE achieving the best result, averaging at 0.266. When compared to other models such as Variance Mode Decomposition-Gated Recurrent Unit (VMD-GRU), Ant Lion Optimizer-Support Vector Machine (ALO-SVM), STL-Particle Swarm Optimization-GRU (STL-PSO-GRU), and STL-Sine Cosine Algorithm-GRU (STL-SCA-GRU), MAE was reduced by 18%, 26%, 11%, and 29%, respectively. This indicates that the model proposed in this study exhibited high prediction accuracy and robust versatility, making it a potent strategic choice for forecasting GWL changes in the context of EWR.

Analysis and prediction of ground deformation in Yinxi Industrial Park based on time-series InSAR technology.

Monitoring ground deformation in industrial parks is of great importance for the economic development of urban areas. However, limited research has been conducted on the deformation mechanism in industrial parks, and there is a lack of integrated monitoring and prediction models. Therefore, this study proposes a comprehensive monitoring and prediction model for industrial parks, utilizing time-series Interferometry Synthetic Aperture Radar (InSAR) technology and the Whale Optimization Algorithm-Back Propagation (WOA-BP) neural network algorithm. Taking Yinxi Industrial Park in Baiyin District as a case study, we used 68 scenes of Sentinel-1A ascending and descending orbit data from June 2018 to April 2021. The Stanford Method for Persistent Scatterers-Permanent Scatterers (StaMPS-PS) and the Small Baseline Subsets-Interferometry Synthetic Aperture Radar (SBAS-InSAR) technologies were employed to obtain the surface deformation information of the park. The deformation information obtained by the two technologies was cross-validated in terms of temporal and spatial distribution, and the vertical and east-west deformation of the park was obtained by combining the ascending and descending orbit data. The results show that the deformation feature points in the line of sight (LOS) direction obtained by the two technologies have a high consistency in spatial distribution, using the ascending orbit data as an example. Additionally, the SBAS-InSAR technology was used to obtain the east-west and vertical deformation results of the park after merging the ascending and descending orbit data for the same period. It was found that the park is mainly affected by vertical deformation, with a maximum subsidence rate of 14.67 mm/yr. The subsidence areas correspond to the deformation positions observed in field survey photos. Based on the ascending orbit deformation data, the two technologies were validated with 585 points of the same latitude and longitude, and the coefficient of determination R2 was found to be 0.82, with a root mean square error (RMSE) of 2.20 mm/a. The deformation rates were also highly consistent. Due to the 47% increase in the number of sampling points provided by the StaMPS-PS technique compared to the SBAS-InSAR technique, the former was found to be more applicable in the industrial park. Based on the ground deformation mechanism in the park, we combined the StaMPS-PS technique with the WOA-BP neural network to construct a deformation zone prediction model. We conducted predictive studies on the deformation zones of buildings and roads within the park, and the results showed that the WOA-optimized BP neural network achieved higher accuracy and lower overall error compared to the unoptimized network. Finally, we analyzed and discussed the geological conditions and inducing factors of ground deformation in the park, providing a reference for a better understanding of the deformation mechanism and early warning of disasters in the industrial park.

Heart rate reduction during voluntary deep diving in free-ranging loggerhead sea turtles.

Air-breathing vertebrates exhibit cardiovascular responses to diving including heart rate reduction (diving bradycardia). Field studies on aquatic mammals and birds have shown that the intensity of bradycardia can vary depending on diving behaviour, such as the depth of dives and dive duration. However, in aquatic reptiles, the variation in heart rate during deep dives under natural conditions has not been fully investigated. In this study, we released five loggerhead sea turtles (Caretta caretta) outfitted with recorders into the sea and recorded their electrocardiogram, depth, water temperature and longitudinal acceleration. After 3 days, the recorders automatically detached from the turtles. The heart rate signals were detected from the electrodes placed on the surface of the plastron. The mean (±s.d.) heart rate of 12.8±4.1 beats min-1 during dives was significantly lower than that of 20.9±4.1 beats min-1 during surface periods. Heart rate during dives varied with dive depth, although it remained lower than that at the surface. When the turtle dived deeper than 140 m, despite the relatively high flipper stroke rate (approximately 19 strokes min-1), the heart rate dropped rapidly to approximately 2 beats min-1 temporarily. The minimum instantaneous heart rate during dives was lower at deeper dive depths. Our results indicate that loggerhead sea turtles show variations in the intensity of diving bradycardia depending on their diving behaviour, similar to that shown by marine mammals and birds.

Conservation energetics of beluga whales: using resting and swimming metabolism to understand threats to an endangered population.

The balance between energetic costs and acquisition in free-ranging species is essential for survival, and provides important insights regarding the physiological impact of anthropogenic disturbances on wild animals. For marine mammals such as beluga whales (Delphinapterus leucas), the first step in modeling this bioenergetic balance requires an examination of resting and active metabolic demands. Here, we used open-flow respirometry to measure oxygen consumption during surface rest and submerged swimming by trained beluga whales, and compared these measurements with those of a commonly studied odontocete, the Atlantic bottlenose dolphin (Tursiops truncatus). Both resting metabolic rate (3012±126.0 kJ h-1) and total cost of transport (1.4±0.1 J kg-1 m-1) of beluga whales were consistent with predicted values for moderately sized marine mammals in temperate to cold-water environments, including dolphins measured in the present study. By coupling the rate of oxygen consumption during submerged swimming with locomotor metrics from animal-borne accelerometer tags, we developed predictive relationships for assessing energetic costs from swim speed, stroke rate and partial dynamic acceleration. Combining these energetic data with calculated aerobic dive limits for beluga whales (8.8 min), we found that high-speed responses to disturbance markedly reduce the whale's capacity for prolonged submergence, pushing the cetaceans to costly anaerobic performances that require prolonged recovery periods. Together, these species-specific energetic measurements for beluga whales provide two important metrics, gait-related locomotor costs and aerobic capacity limits, for identifying relative levels of physiological vulnerability to anthropogenic disturbances that have become increasingly pervasive in their Arctic habitats.

A pan-cetacean MHC amplicon sequencing panel developed and evaluated in combination with genome assemblies.

The major histocompatibility complex (MHC) is a highly polymorphic gene family that is crucial in immunity, and its diversity can be effectively used as a fitness marker for populations. Despite this, MHC remains poorly characterised in non-model species (e.g., cetaceans: whales, dolphins and porpoises) as high gene copy number variation, especially in the fast-evolving class I region, makes analyses of genomic sequences difficult. To date, only small sections of class I and IIa genes have been used to assess functional diversity in cetacean populations. Here, we undertook a systematic characterisation of the MHC class I and IIa regions in available cetacean genomes. We extracted full-length gene sequences to design pan-cetacean primers that amplified the complete exon 2 from MHC class I and IIa genes in one combined sequencing panel. We validated this panel in 19 cetacean species and described 354 alleles for both classes. Furthermore, we identified likely assembly artefacts for many MHC class I assemblies based on the presence of class I genes in the amplicon data compared to missing genes from genomes. Finally, we investigated MHC diversity using the panel in 25 humpback and 30 southern right whales, including four paternity trios for humpback whales. This revealed copy-number variable class I haplotypes in humpback whales, which is likely a common phenomenon across cetaceans. These MHC alleles will form the basis for a cetacean branch of the Immuno-Polymorphism Database (IPD-MHC), a curated resource intended to aid in the systematic compilation of MHC alleles across several species, to support conservation initiatives.

Downsizing a heavyweight: factors and methods that revise weight estimates of the giant fossil whale Perucetus colossus.

Extremes in organismal size have broad interest in ecology and evolution because organismal size dictates many traits of an organism's biology. There is particular fascination with identifying upper size extremes in the largest vertebrates, given the challenges and difficulties of measuring extant and extinct candidates for the largest animal of all time, such as whales, terrestrial non-avian dinosaurs, and extinct marine reptiles. The discovery of Perucetus colossus, a giant basilosaurid whale from the Eocene of Peru, challenged many assumptions about organismal extremes based on reconstructions of its body weight that exceeded reported values for blue whales (Balaenoptera musculus). Here we present an examination of a series of factors and methodological approaches to assess reconstructing body weight in Perucetus, including: data sources from large extant cetaceans; fitting published body mass estimates to body outlines; testing the assumption of isometry between skeletal and body masses, even with extrapolation; examining the role of pachyostosis in body mass reconstructions; addressing method-dependent error rates; and comparing Perucetus with known physiological and ecological limits for living whales, and Eocene oceanic productivity. We conclude that Perucetus did not exceed the body mass of today's blue whales. Depending on assumptions and methods, we estimate that Perucetus weighed 60-70 tons assuming a length 17 m. We calculated larger estimates potentially as much as 98-114 tons at 20 m in length, which is far less than the direct records of blue whale weights, or the 270 ton estimates that we calculated for body weights of the largest blue whales measured by length.

A statistical acoustics approach for estimating population-scale bowhead whale migration speed and direction.

Bowhead whales vocalize during their annual fall migration from the Beaufort Sea to the Bering Sea, but the calling rates of individual animals are so low that tracking an individual trajectory is impractical using passive acoustic methods. However, the travel speed and direction of the migrating population can be inferred on a statistical basis by cross-correlating time sequences of call density measured at two locations spaced several kilometers apart. By using the triangulation abilities of a set of vector sensors deployed offshore the Alaskan North Slope between 2008 and 2014, call density time sequences were generated from 1-km wide and 40-km tall rectangular "zones" that were separated by distances ranging from 3.5 to 15 km. The cross-covariances between the two sequences generate a peak corresponding to the average time it takes for whales to travel between the zones. Consistent westward travel speeds of ∼5 km/h were obtained from four different locations on 6 of the 7 years of the study, independent of whether the zones were separated by 3.5, 7, or 15 km. Some sites, however, also revealed a less prominent eastern movement of whales, and shifts in migration speed were occasionally detectable over week-long time scales.