Microplastics in muscle and blubber of the Pacific walrus (Odobenus rosmarusdivergens).

Sea lions as a natural model for charting the developmental course following in utero exposure to domoic acid.

Accumulation of trace elements in harbour porpoises and their selected helminths: a study from the North Sea and the Baltic Sea.

Marine mammals as global bioindicators of PFAS pollution: A review of advanced analytical methods and machine learning for source apportionment

Sperm whale acoustic ecology around two sub-Antarctic islands.

Spatial and temporal distribution patterns of marine mammals in the southern Sea of Okhotsk around Hokkaido, Japan

Exposure and magnification of PFAS in a temperate estuarine food web, including top predators.

Identification and characterization of broad-spectrum cathelicidin family antimicrobial peptides from the pygmy sperm whale Kogia breviceps.

Background: In the frame of our long-term study in polar seas, the at-sea distribution of “top predators” – seabirds and marine mammals – was studied in the Weddell Sea area, both the well-covered northern one (sub-antarctic Scotia Sea) as well as in the almost unexplored southern and central ones. Method was our usual transect counts lasting 30 min. each, without width limitation. Results and conclusions: Species richness was low, dominated by only a few species, reflecting low diversity. Birds, seals and to some extend whales showed a heterogeneous distribution. They were concentrated in a few “hotspots” on the “continental” shelf and –slope, of South Georgia, South Sandwich and South Shetland (Elephant) islands, and off the Peninsula. Species showed important differences in distribution probably reflecting differences in the food web. In open waters off the shelf, species showed low densities, both in the northern and southern areas. In the case of seabirds, moreover, they were partially over-estimated by the presence of long-distance followers, probably by one order of magnitude. The absence of gentoo penguin might reflect a change in geographical distribution.

Body condition, the relative amount of energy reserves in an individual, reflects nutritional status and overall health in marine mammals and can indicate the influence of stressors on individuals. Energy in marine mammals is primarily stored as lipids within adipocytes in blubber tissue, making blubber thickness a common proxy for body condition. However, blubber also serves structural roles, complicating its use as a body condition indicator. Our objective was to assess the relationship between adipocyte size, a common measure of cetacean adiposity, and blubber thickness in beluga whales (Delphinapterus leucas). We used mixed-effect generalized linear models to test how sex and blubber layer influenced this relationship. We found a significant positive relationship between adipocyte size and blubber thickness in male but not female beluga whales, suggesting sex-specific differences in fat storage or mobilization. Blubber thickness may be maintained in female beluga whales during periods with low energy reserves, for example during gestation and lactation, to preserve buoyancy, insulation, and hydrodynamism, which may be especially important when supporting swimming calves. Continuing to develop methods to assess beluga whale health will further our understanding of the impact of current and future stressors on beluga whale populations.

Many aquatic animals have a well-developed sense of hearing as sound is important for communication underwater. However, this trait leaves them susceptible to injury, and physiological and behavioral impacts from exposure to intense or persistent anthropogenic sounds. We provide an overview of the current state of knowledge on the physiological effects of five main sources of anthropogenic sound: marine traffic, seismic exploration, pile driving, other industrial activity and sonar. Our understanding of impacts varies greatly by sound type and taxon, although the studied species do not represent the full taxonomic diversity. Exposure to ship sounds has been best studied in fish and it generally leads to responses along the stress response cascade, while few studies have been conducted on its physiological effect on invertebrates or marine mammals. Effects of exposure to seismic sound show mixed impact across taxa. Pile driving sounds have been shown in captive studies to result in hearing impairment in marine mammals and can cause injury to fishes. Lethal impacts have been documented from naval sonar on marine mammal species. Currently, physiological impacts from other industrial sound sources are poorly documented across taxa. Overall, given the limited number of species examined in sound impact experiments, it is crucial to establish categorizing principles and guidelines and modeled response pathways to improve management strategies, especially as new sound threats continue to emerge in our changing world.

Abstract A recently discovered site in southern Mississippi considered early Arikareean based on identified mammals represents the first of this age from the Gulf Coastal Plain outside of Florida. The Jones Branch Local Fauna was recovered from deltaic/estuarine deposits low in the Catahoula Formation resting unconformably on marl/clay beds of the subjacent, upper Rupelian (lower Oligocene), marine Paynes Hammock Formation. In addition to well-preserved plant material plus reptiles, amphibians, and fishes, the mammals are represented primarily by species previously known almost exclusively from the Great Plains, the northern Rocky Mountains (Montana), and/or John Day region, Oregon, with only a few apparently endemic to the Gulf Coastal Plain. Genera representative of the former include the proscalopid Mesoscalops , the sciurid Hesperopetes , the aplodontiid Downsimus , the putative early castoroid Eutypomys , the castorid Microtheriomys , the eomyids Apeomys and Leptodontomys , the florentiamyid Kirkomys , the mustelids Corumictis and Promartes , the tapir Protapirus , the leptochoerid Leptochoerus , the anthracothere Elomeryx , and the hornless ruminants Hypertragulus and ? Leptomeryx. Mesoscalops , Downsimus , and Apeomys are represented by new species. Additionally, a new genus and species of lagomorph is described, Oligolagus welleri , as is a new genus and new species of eomyid, Paraktioeomys palmeri. Known from both regions is the marsupial Herpetotherium , an apatemyid provisionally referred to Sinclairella , and the borophagine Phlaocyon. Gulf Coastal Plain endemics include the protoceratid Prosynthetoceras orthrionanus and apparently Oligolagus n. gen. and Paraktioeomys n. gen. The geographically broadly distributed horse Miohippus , rhinoceros Diceratherium , and giant entelodont Daeodon are also present. Marine mammals are represented by the dugong Crenatosiren olseni and the odontocete Agorophius pygmaeus. Additionally noted are two taxa from stratigraphically lower formations that are not part of the Jones Branch LF. These include a large species of the entelodont Archaeotherium and the anthracothere Elomeryx armatus , both of which were previously unknown along the Gulf Coastal Plain. The long recognized biotic disparity between the Midcontinent and Gulf Coastal Plain by the early Miocene was not yet strongly apparent during the early to middle Oligocene. UUID: http://zoobank.org/c1b57f31-4ed1-42fb-bf31-c803e2e61cfd

Ultrasound diagnostics in stranded wild dolphins allows for the rapid identification of a number of underlying problems and prompt initiation of treatment. Ultrasound diagnostics for animals kept in captivity is no less important. Regular clinical observation and chest ultrasound examinations can effectively detect most diseases at an early compensatory stage, without waiting for a sharp deterioration in condition or decompensation [2-4]. In this regard, radiographic examinations are inferior to ultrasound due to their ability to assess only the overall condition of the chest cavity, the high cost and safety issues associated with using the equipment, and the impossibility of regular dynamic assessment due to the constant exposure to ionizing radiation [1]. This paper presents a method for ultrasound examination of the respiratory system in both wild and captive marine mammals. The non-invasive nature of this method and the potential for detailed real-time assessment of

Following near‐extinction from 20th‐Century industrial whaling, fin whales are now reappearing in growing numbers in Antarctic waters. Shipboard and aerial surveys have documented their return to ancestral feeding grounds along the Western Antarctic Peninsula. Using behavioural analyses based on satellite telemetry data, this study aims to complement existing knowledge on the ecology of fin whales, with insights into movement patterns and behaviour at feeding grounds that support some of the largest aggregations of baleen whales ever observed. In the austral autumn (March and April) of 2021 and 2023, four and nine fin whales, respectively, were equipped with satellite transmitters at their foraging grounds off Elephant Island. Their movements were tracked for durations ranging from 4 to 39 days (SD = 9 days). Behavioural analyses employing a two‐state Hidden‐Markov model (HMM) were conducted to assess the whales’ activity states. The HMM revealed that fin whales dedicated almost 80% of their time to area‐restricted search, a behaviour commonly associated with foraging. Most individuals (n = 8) exhibited a notable site fidelity to the waters off the Northern coast of Elephant Island. Three whales moved away from the tagging location in different directions: south‐west into the Bransfield Strait, east towards the South Orkneys, and south towards the Weddell Sea, where they again engaged in area‐restricted search. The concentration of foraging behaviour around Elephant Island, the South Orkneys and the Northern region of the Weddell Sea highlights known and potentially novel core feeding grounds within the Western Antarctic Peninsula and Islands IMMA (Important Marine Mammal Area). The identification of these foraging areas within an IMMA strengthens the urgent need for special protection to ensure the continued recovery of this species and preserve core feeding habitats.

Marine mammals have high potential for dispersal, yet behavioral or environmental constraints can limit gene flow. This is true for the endangered sperm whale, Physeter macrocephalus, which has a global distribution and long-distance migrations. While previous studies revealed mitochondrial population structure with weak nuclear structure globally, genomic approaches examining this pattern have been limited. Understanding connectivity is critical for the management of this species due to population declines relative to pre-whaling numbers and increased recent anthropogenic stressors. We investigated connectivity between two regions, the U.S. Gulf of Mexico and the western North Atlantic Ocean, using reduced representation genomic and mitochondrial control region sequencing of 73 sperm whales. Relatedness decreased with geographic distance, likely due to the presence of social groups and familial structure. Nuclear markers showed no population structure (FST = 0.001-0.008), while mitochondrial structure was high (FST = 0.36-0.65), consistent with male-biased dispersal and female philopatry. Female-only analyses showed higher differentiation for mitochondrial but not nuclear markers; male-only analyses revealed no structure. Across all samples, genetic diversity (nuclear: 0.0014; mitochondrial: 0.0017) and effective population size (Ne = 460) were low. Given this low diversity and evidence for partitioning of genetic variation, we recommend managers treat these two regions as distinct to preserve existing variation and promote resilience of this species. These results illustrate that despite the increased power of a genomic approach, it is essential to consider the biology of the species at hand and leverage both mitochondrial and nuclear markers to understand the genetic structure of threatened species.

Marine mammals, fish and fisheries exploit overlapping prey resources; yet the causal nature of their interactions remains unresolved due to limited data and complex ecosystem dynamics. In this study, we combine food web modelling with causal inference to quantify causal effects between marine mammals and commercially important fish species in the Norwegian Sea and Barents Sea. We first extract multiple food web dynamics from an existing mass-balanced linear inverse food web model and use these as inputs to causal modelling. A key methodological step is to translate the food web network into a temporally explicit causal diagram. By mapping biomass flows onto causal links, we quantify causal effects for both the short term (1 year lag) and the long term (30 year simulation). We find that the increase in marine mammal biomass has predominantly negative and potentially large-but highly uncertain-effects on fish biomass. In contrast, an increase in fish biomass produces smaller, positive effects on marine mammals. Long-term simulations reveal dampened impacts, indicating partial compensation over time. The results from this study, which combines food web dynamics modelling with causal inference, can support more precise, data-informed and ecologically grounded fisheries and marine mammal management in the North Atlantic.

Per- and polyfluoroalkyl substances (PFAS) continue to increase in concentration and prevalence in the environment due to the creation of emerging PFAS and the lack of breakdown of legacy compounds. PFAS are known to both bioaccumulate and biomagnify; therefore, species higher on the food chain, such as marine mammals, are highly exposed to these chemicals. Although studies suggest that considerable maternal transfer of persistent organic pollutants occurs via lactation, data are still lacking on the temporal trends associated with PFAS exposure. In this study, we first optimized the extraction for PFAS from 5 and 1mL of goat's milk using a QuEChERS extraction method to account for precious breast milk samples that are often only available in small volumes. We then utilized a set of dolphin breastmilk samples from an individual mother across a 2-year lactation period to evaluate longitudinal trends in PFAS concentrations and profiles. Thirty PFAS were detected using a multidimensional platform combining liquid chromatography, ion mobility spectrometry, and mass spectrometry (LC-IMS-MS), and of these, 20 PFAS were detected continuously across the nursing window of 103-706days. Quantitative analysis using LC-IMS-MS specifically showed concentrations of perfluorooctanesulfonic acid (PFOS) alone surpass weekly intake recommendations, allometrically scaled to dolphins, from the European Food Safety Authority and Food Standards Australia New Zealand by more than 25-fold. PFOS, however, decreased slightly over time, possibly due to transfer from feedings. Suspect screening and non-targeted analysis also identified 12 compounds including 2 long-chained perfluorosulfonic acids not traditionally evaluated in targeted analyses, as well as the PFOS precursors, perfluoroethylcyclohexane sulfonate (PFECHS) and 2-(N-ethylperfluorooctanesulfonamido) ethyl phosphate (SAmPAP). This study therefore suggests that breastmilk is a major contributor to early-life PFAS exposure for mammals, particularly to long-chained PFAS.

We used immunohistochemistry and PCR to identify Neospora caninum in 6 infected marine mammal species, including 2 pups, that stranded in the northeastern Pacific Ocean. Our findings suggest the expansion of this parasite's host range to marine mammals, underscoring the effect of terrestrial pathogens that flow from land to sea.

An effect factor for macro- and microplastic ingestion impacts on marine ecosystems for use in life cycle assessment.

High accumulation and potential health risks of organic ultraviolet absorbents in humpback dolphins from the South China Sea.