Search Results (269)

Photobacterium damselae subsp. damselae (Pdd) is an increasingly common bacterium in post-mortem diagnostics of beached marine mammals, but little is known about its precise etiological responsibility. To estimate the prevalence of Pdd in stranded cetaceans from 2017 to 2022 on the Ligurian coast (Pelagos Sanctuary), we tested tissues from 53 stranded individuals belonging to four cetacean species. DNA extracts from cetacean tissue were screened using a polymerase chain reaction (PCR) assay targeting the Pdd ureC gene. Positive samples were screened by PCR for dly, hlyA_pl and hlyA_ch hemolysin genes, which were confirmed by sequencing. Twenty-two out of 53 (41.5%) cetaceans analyzed by PCR were confirmed for Pdd DNA in at least one tissue among those analyzed. Five of these cetaceans were positive for at least one of the hemolysin genes tested. In all Pdd-positive cetaceans, other pathogens that were considered responsible for the causa mortis of the animals were also found. The results provide new information on the spread of Pdd in cetaceans and support the thesis that Pdd might be an opportunistic agent that could contribute to worsening health conditions in subjects already compromised by other pathogens. However, further studies are needed to investigate and deepen this hypothesis. Full article

The franciscana dolphin (Pontoporia blainvillei) is a small cetacean endemic to the coastal waters of the southwestern Atlantic Ocean. Due to its restricted distribution, it is subject to high bycatch mortality in the gillnets used for commercial and artisanal fishing. The rehabilitation of the franciscana is still a major challenge, as most attempts to rehabilitate stranded animals have failed. This study aims to present the case of the rehabilitation of a franciscana dolphin calf, stranded in San Clemente del Tuyú, Argentina, at the beginning of the predation period. The feeding strategy and nutritional profile at different stages during the 88 days of rehabilitation are meticulously detailed. Its diet was prepared by hand based on studies of milk composition, the feeding ecology of franciscana in Argentinean waters, and previous records of the Fundación Mundo Marino Rehabilitation Center. The diets were designed to meet the nutritional needs of franciscana dolphins. In addition, the hematological, cytological, and fecal analyses recorded during the rehabilitation are presented. Although the animal could not be released, due to its death, this report provides baseline information that can improve the ability of veterinarians to care for debilitated, live-stranded dolphins. This information may also be useful in the implementation and development of healthcare protocols for this species. Full article

This case report presents the first molecular identification of a gammacoronavirus in a free-ranging striped dolphin (Stenella coeruleoalba) that was found stranded along the Croatian coastline in 2022. The dolphin exhibited a concurrent infection with cetacean morbillivirus. The gammacoronavirus strain was amplified and sequenced from heart tissue imprinted on an FTA^®card, revealing a notable genetic distance (approximately 8%) from previously characterized cetacean gammacoronaviruses. This finding highlights the importance of including gammacoronaviruses in routine diagnostics for stranded dolphins to gather epidemiological data on their prevalence and potential role in causing disease in cetaceans. This study sets the premises for a further understanding of the diversity and distribution of gammacoronaviruses in marine mammals and highlights the necessity for ongoing surveillance of emerging infectious diseases in wild populations. Full article

The Galapagos Marine Reserve is vital for cetaceans, serving as both a stopover and residency site. However, blue whales, occasionally sighted here, exhibit poorly understood migratory behavior within the Galapagos and the broader Eastern Tropical Pacific. This study, the first to satellite tag blue whales in the Galapagos (16 tagged between 2021 and 2023), explored their behavior in relation to environmental variables like chlorophyll-a concentration, sea surface temperature (SST), and productivity. Key findings show a strong correlation between foraging behavior, high chlorophyll-a levels, productivity, and lower SSTs, indicating a preference for food-rich areas. Additionally, there is a notable association with geomorphic features like ridges, which potentially enhance food abundance. Most tagged whales stayed near the Galapagos archipelago, with higher concentrations observed around Isabela Island, which is increasingly frequented by tourist vessels, posing heightened ship strike risks. Some whales ventured into Ecuador’s exclusive economic zone, while one migrated southward to Peru. The strong 2023 El Niño–Southern Oscillation event led to SST and primary production changes, likely impacting whale resource availability. Our study provides crucial insights into blue whale habitat utilization, informing adaptive management strategies to mitigate ship strike risks and address altered migration routes due to climate-driven environmental shifts. Full article

The Natural History Museum of the University of Pisa hosts the most important osteological collection of extant cetaceans in Italy as well as one of the most relevant all over Europe. Furthermore, it also preserves a significant palaeontological collection that includes several holotypes and otherwise unique specimens of Archaeoceti (archaic cetaceans), Mysticeti (baleen whales) and Odontoceti (toothed whales). Here, we provide a historical overview of these collections and the corresponding displays, with special attention paid to the origin, development and design of the ‘Archaeocete Hall’ and ‘Cetacean Gallery’. These comprise what may be the largest exhibition worldwide among those dedicated exclusively to cetaceans—one that includes 28 complete skeletons and one skull belonging to 27 extant species as well as fossils of nine extinct species. Our review also reveals that the museum exhibitions feature the oldest known specimen of Mesoplodon bowdoini and the type specimen of Ziphius savi, the latter being a validly described species that is currently regarded as a junior synonym of Ziphius cavirostris. Also significant is the display of several holotype specimens of fossil species such as the protocetid archaeocete Aegyptocetus tarfa, the balaenid baleen whales Balaena montalionis and Balaenula astensis, and the monodontid Casatia thermophila. The Archaeocete Hall and Cetacean Gallery are highly appreciated by visitors as well as perused by the museum’s educational team. The online archiving of 3D models of many of the MSNUP specimens on the open-access digital repository Sketchfab and their subsequent dissemination through the Wikimedia platforms has led to the creation of a major osteological resource—one that is broadly accessible to internet users worldwide. Full article

The monitoring of stranded marine mammals represents a strategic method to assess their health, conservation status, and ecological role in the marine ecosystem. Networks worldwide track stranding events for the passive monitoring of mortality patterns, emerging and reemerging pathogens, climate change, and environmental degradation from a One Health perspective. This study summarizes pathogen prevalence data from the Italian Stranding Network (ISN) derived from post-mortem investigations on cetaceans found dead stranded along the Italian coastline between 2015 and 2020. The decomposition of the carcasses and logistics limited the post-mortem examination to 585 individuals, out of 1236 single-stranding reports. The most relevant pathogens identified were Cetacean Morbillivirus, Herpesvirus, Brucella spp., and Toxoplasma gondii, whose roles as environmental stressors are well known, despite their real impact still needing to be investigated in depth. Statistical analysis showed that age and sex seem to be positively related to the presence of pathogens. This study represents the first step in harmonizing post-mortem investigations, which is crucial for evidence-based conservation efforts. Implementing diagnostic and forensic frameworks could offer an indirect insight into the systematic monitoring of diseases to improve the identification of regional and temporal hotspots in which to target specific mitigation, management, and conservation strategies. Full article

The marine parasitic nematode Anisakis simplex has a complex life cycle including marine mammals (mainly cetaceans) as definitive hosts, invertebrates (e.g., copepods and euphausiids) as the first paratenic hosts, and a wide range of fish species acting as second paratenic hosts. During the life cycle, the larva encounters a wide range of biotic (host immune factors and microelectric activity) and abiotic conditions (temperature and pH). We hypothesized that these factors may explain the differential behaviour of the nematode, recognized during the different life cycle stages. In this study, third-stage larvae (L3) of A. simplex were isolated from freshly caught Atlantic herring (Clupea harengus) from FAO zone 27. We exposed nematodes to different pH values (pH 2 to 9) at different temperature levels (4, 14, 21 and 37 °C), electric currents (6 mA, 12 mA, 18 mA) and different concentrations of fish immune cells. The nematode larvae exhibited significantly differential behaviour (stretched non-aggregated, spiral non-aggregated and aggregated) and activity levels when exposed to the different physicochemical conditions. We recorded negative correlations between activity and pH (maximum at pH 2) and positive correlations between activity and temperature (maximum at 37 °C). The nematode larvae were affected when exposed to electricity and fish immune cells. Electric currents at 6 mA induced minor changes, but at 12 mA and 18 mA, the majority or all nematode larvae aggregated and rolled up into spirals. Exposure to leukocytes, isolated from rainbow trout head kidney and spleen, induced a similar concentration-dependent spiralling process in larvae. We discuss these behavioural patterns of A. simplex as adaptations to conditions encountered by the worm larvae during the different stages of their complex life cycle. Full article

This study outlines the procedures used for collecting, processing, and categorizing data on 16 new mammal species for mainland Portugal, belonging to four taxonomic groups: Eulipotyphla (1), Chiroptera (4), Rodentia (2), and Cetacea (9). Data collection and processing encompassed field and lab work and bibliographic compilation. Data categorization involves, whenever possible, the assessment of the approximate number of mature individuals in populations, the extent of occurrence, and the area of occupancy. The approach employed led to the classification of eight out of the 16 species into an IUCN category: two non-volant small mammals and one bat species were designated as Vulnerable, requiring ongoing monitoring; one rodent and three cetaceans were assigned to Data Deficient due to insufficient available information; and a single bat species was classified as Least Concern due to the high abundance of local populations. For small mammals and bats, alterations to natural systems and climate change emerged as the most relevant threatening factors, while for cetaceans, human activities such as fishing, commercial shipping, and tourism were identified as the primary survival risks. It is recommended to maintain action programs that assist in defining strategic orientations for the implementation of conservation measures on a case-by-case basis. Full article

Neurobrucellosis in cetaceans, caused by Brucella ceti, is a relevant cause of death in striped dolphins (Stenella coeruleoalba) from the Mediterranean Sea. Serological tests are not used as a routinary technique for the diagnosis of this infection. We briefly describe the pathological findings of nine free-ranging stranded cetaceans diagnosed with Brucella disease or infection in our veterinary necropsy service from 2012 to 2022. The findings included focal diskospondylitis and non-suppurative meningitis, choroiditis and radiculitis. Additionally, an exploratory serological study was conducted in sixty-six frozen sera collected in the period 2012–2022 from fifty-seven striped dolphins, five Risso’s dolphins (Grampus griseus), two common bottlenose dolphins (Tursiops truncatus), one common dolphin (Delphinus delphis) and one pilot whale (Globicephala melas) to compare antibody levels in Brucella-infected (n = 8) and non-infected (n = 58) animals, classified by the cause of death, sex, age class and cetacean morbillivirus (CeMV) infection status. The authors hypothesized that active infection in cases of neurobrucellosis would elicit a stronger, detectable humoral response compared to subclinical infections. We performed a commercial competition ELISA (cELISA) using serial serum dilutions for each sample, considering a percentage of inhibition (PI) of ≥40% as positive. A titer of 1:160 was arbitrarily determined as the seropositivity threshold. Seropositive species included striped dolphins and Risso’s dolphins. Seroprevalence was higher in animals with neurobrucellosis (87.5%) compared to the overall seroprevalence (31.8%) and to other causes of death, indicating, likely, a high sensitivity but low specificity for neurobrucellosis. Animals with chronic CeMV seemed to have higher seroprevalences, as well as juveniles, which also had a higher disease prevalence. These results indicate, as in other studies, that antibodies are not decisive against clinical brucellosis, although they may indicate a carrier state, and that CeMV may influence Brucella epidemiology. More research is required to elucidate the epidemiology and pathogenesis and to resolve the complicated host–pathogen interaction in Brucella species. Full article

Despite decreasing anthropogenic mercury (Hg) emissions in Europe and the banning and restriction of many persistent organic pollutants (POPs) under the Stockholm Convention, Mediterranean marine mammals still have one of the highest body burdens of persistent pollutants in the world. Moreover, the Mediterranean basin is one of the most sensitive to climate change, with likely changes in the biogeochemical cycle and bioavailability of Hg, primary productivity, and the length and composition of pelagic food webs. The availability of food resources for marine mammals is also affected by widespread overfishing and the increasing number of alien species colonizing the basin. After reporting the most recent findings on the biogeochemical cycle of Hg in the Mediterranean Sea and the physico-chemical and bio-ecological factors determining its exceptional bioaccumulation in odontocetes, this review discusses possible future changes in the bioavailability of the metal. Recent ocean–atmosphere–land models predict that in mid-latitude seas, water warming (which in the Mediterranean is 20% faster than the global average) is likely to decrease the solubility of Hg and favor the escape of the metal to the atmosphere. However, the basin has been affected for thousands of years by natural and anthropogenic inputs of metals and climate change with sea level rise (3.6 ± 0.3 mm year⁻¹ in the last two decades), and the frequency of extreme weather events will likely remobilize a large amount of legacy Hg from soils, riverine, and coastal sediments. Moreover, possible changes in pelagic food webs and food availability could determine dietary shifts and lower growth rates in Mediterranean cetaceans, increasing their Hg body burden. Although, in adulthood, many marine mammals have evolved the ability to detoxify monomethylmercury (MMHg) and store the metal in the liver and other organs as insoluble HgSe crystals, in Mediterranean populations more exposed to the metal, this process can deplete the biological pool of Se, increasing their susceptibility to infectious diseases and autoimmune disorders. Mediterranean mammals are also among the most exposed in the world to legacy POPs, micro- and nanoplastics, and contaminants of emerging interest. Concomitant exposure to these synthetic chemicals may pose a much more serious threat than the Se depletion. Unfortunately, as shown by the literature data summarized in this review, the most exposed populations are those living in the NW basin, the main feeding and reproductive area for most Mediterranean cetaceans, declared a sanctuary for their protection since 2002. Thus, while emphasizing the adoption of all available approaches to mitigate anthropogenic pressure with fishing and maritime traffic, it is recommended to direct future research efforts towards the assessment of possible biological effects, at the individual and population levels, of chronic and simultaneous exposure to Hg, legacy POPs, contaminants of emerging interest, and microplastics. Full article

This article deals with Central Nervous System (CNS) disorders of marine mammals as putative neuropathology and neuropathogenesis models for their human and, to some extent, their animal “counterparts” in a dual “One Health” and “Translational Medicine” perspective. Within this challenging context, special emphasis is placed upon Alzheimer’s disease (AD), provided that AD-like pathological changes have been reported in the brain tissue of stranded cetacean specimens belonging to different Odontocete species. Further examples of potential comparative pathology interest are represented by viral infections and, in particular, by “Subacute Sclerosing Panencephalitis” (SSPE), a rare neurologic sequela in patients infected with Measles virus (MeV). Indeed, Cetacean morbillivirus (CeMV)-infected striped dolphins (Stenella coeruleoalba) may also develop a “brain-only” form of CeMV infection, sharing neuropathological similarities with SSPE. Within this framework, the global threat of the A(H5N1) avian influenza virus is another major concern issue, with a severe meningoencephalitis occurring in affected pinnipeds and cetaceans, similarly to what is seen in human beings. Finally, the role of Brucella ceti-infected, neurobrucellosis-affected cetaceans as putative neuropathology and neuropathogenesis models for their human disease counterparts is also analyzed and discussed. Notwithstanding the above, much more work is needed before drawing the conclusion marine mammal CNS disorders mirror their human “analogues”. Full article

A female narrow-ridged finless porpoise (Neophocaena asiaeorientalis) stranded on a beach on Jeju Island showed epithelial proliferative skin lesions on its body. Two false killer whales (Pseudorca crassidens), caught using nets near Gangneung and Samcheok, respectively, had multiple plaques on their penile epidermis. Histological examination of the epidermis revealed that all the lesions had common features, including accentuated rete pegs, ballooning changes, and eosinophilic intranuclear inclusion (INI) bodies. Based on the histopathological results, herpesvirus infection was suspected, and thus further analysis was conducted using herpesvirus-specific primers. Based on nested polymerase chain reaction (PCR) tests using the herpesvirus-detectable primers, the PCR products demonstrated two fragments: a 222-base-pair (bp) sequence of the DNA polymerase gene, SNUABM_CeHV01, showing 96.4% identity with a bottlenose dolphin herpesvirus from the Jeju narrow-ridged finless porpoise; and a 222 bp sequence of the DNA polymerase gene, SNUABM_CeHV02, showing 95.95% identity with the same bottlenose dolphin herpesvirus from the Gangneung and Samcheok false killer whales. The significance of this study lies in its ability to demonstrate the existence of novel cetacean herpesviruses in South Korean seawater, representing an important step forward in studying potentially harmful pathogens that affect endangered whale and dolphin populations. Full article

Sepetiba Bay, located in southwestern Rio de Janeiro state, in southeastern Brazil, is a region of extreme anthropogenic impact, and is home to a large population of Guiana dolphins, which face increasing and cumulative pressures on their physical health. Cetacean body condition provides a useful indicator for the evaluation of the conservation status of marine mammals. Given this, the present study quantified the proportion of dolphins with different body condition scores and assessed temporal variation in these scores between 2017 and 2022 through the analysis of photographic records. We analyzed the photographs and identified the individuals using FinFindR and classified each individual based on its apparent body condition. A total of 29,737 photographs were taken during the study, and 79 individuals were identified, of which 68.35% were in poor condition. The evidence suggests that the Guiana dolphins are in relatively poor condition overall, possibly reflecting the cumulative impact of human activities in Sepetiba Bay. Full article

Cetacean strandings are valuable sources of data about their life history, health status, population trends, and impact of threats. We examined the strandings along the Bulgarian coast of the Black Sea for a period of 13 years from 2010 to 2022. A total of 1528 cetacean strandings of all three species inhabiting the basin were recorded: 1031 harbour porpoises Phocoena phocoena, 199 bottlenose dolphins Tursiops truncatus, 97 common dolphins Delphinus delphis, 19 delphinids and 182 unidentified. The highest numbers were observed in 2016 and 2022. Monthly peaks for harbour porpoise and bottlenose dolphin were in July and August and for common dolphin in May. An unusually high mortality of porpoise neonates was recorded in 2015 and 2016. The overall sex ratio showed a slightly higher share of males at 120:100. This bias was the most pronounced for males of common dolphins. Spatial distribution varied interspecifically but was predominantly along the southern coast. Bycatch signs were detected in 80 animals including during the turbot fishing ban period, suggesting the existence of illegal fishing operations. All of this highlights the need for better reinforcement and control to ensure both the conservation of endangered cetaceans and the sustainability of fisheries. Improvement in data collection is needed to improve the quality of information. Full article

A national cetacean stranding response program in Taiwan has evolved significantly in the past three decades. Initially co-ordinated by National Taiwan University from 1994, the program transitioned to the Taiwan Cetacean Society in 1999, and local governments took on a more prominent role after 2009. A comprehensive stranding database (1994–2018) has been maintained, which documented 1320 stranding events involving 1698 animals from at least 27 species. The most commonly stranded species include finless porpoises, bottlenose dolphins, Kogia spp., and Risso’s dolphins. The stranding rates varied annually and seasonally, with increases noted from an average of 16 events per year for the first 3 years to 44–58 events per year between 1997 and 2015, and a sharp rise to over 90 events per year for the period of the last three years. Seasonal variations were also significant, with higher stranding rates during the northeastern monsoon (NEM, October to next April) than that during southwestern monsoon (SWM, May to September). From the aspect of distribution, more frequent and even strandings occurred along the coast of northern Taiwan, while mass strandings were concentrated in the southwestern counties during NEM. Among all strandings, 390 events (29.5%) and 660 animals (38.9%) were live ones. Under great effort in rescuing and rehabilitating 52 cases, 15 cetacean individuals have been released since 2000. Additionally, there have been 56 mass strandings involving at least 11 species since 1994, predominated by pygmy killer whales, particularly during the NEM season along the southwest coast. This study not only contributes to our understanding of the stranding patterns and diversity of the cetaceans in Taiwan, but also provides valuable insights for future conservation strategies on cetaceans in the western Pacific. Full article