Marine mammals as sentinel species for oceans and human health

Neonatal Abandonment and Hydrocephalus in Antillean Manatees (Trichechus manatus manatus): Is There a Causal Relationship?

Manatees are semi-social animals, with the mother-calf relationship being considered long-lasting for the species. However, some events lead to the separation of this pair. Orphaned manatee calves can be adopted by other females of the same species. However, if this does not happen and a healthy calf strand is rescued, immediate release represents the best option for the individual. But when immediate release becomes unviable, the animals are taken to rehabilitation centers and can die from various causes. A newborn Antillean manatee was rescued in the north of Brazil, and the attempt at immediate release was unsuccessful; three months later, the animal died. At necropsy, it was observed that the brain was soft and friable, collapsing when placed on a surface, with the corpus callosum region able to be ruptured easily and the cerebral hemispheres lying flaccid. The analysis of serial sections of the brain showed dilated lateral ventricles and a reduction in white matter, making it possible to affirm the presence of congenital hydrocephalus, the main factor that may have led to the abandonment of the offspring.

Target, suspect, and non-target analysis of halogenated organic pollutants in spotted seals (Phoca largha) from Peter the Great Bay, East Sea/Sea of Japan

Target, suspect, and non-target analyses were conducted to investigate the accumulation status of halogenated organic pollutants (HOPs) in spotted seals (Phoca largha Pallas, 1811) from Peter the Great Bay, East Sea/Sea of Japan. Despite long-standing regulations, polychlorinated biphenyls (PCBs) and organochlorine pesticides were highly accumulated, likely due to placental and lactational transfer. Hexabromocyclododecanes were the predominant brominated flame retardants, with their levels increasing with age. Suspect and non-target analyses identified 35 non-target PCBs not routinely monitored, suggesting conventional methods may underestimate PCB concentrations. Regression analysis showed significant correlations between the concentrations of major PCBs (CBs 138 and 153) and the sum of target and non-target PCBs. The study found that 95 % of the seals exceeded threshold levels for PCBs, posing potential health risks. These findings highlight the need for integrated monitoring, combining target and non-target analyses, to better assess and manage the risks of HOPs to marine mammals.

Cetacean species found stranded along Croatian coast of the Adriatic Sea as bioindicators of non-essential trace elements in the environment

In tissues of toothed whales from the Adriatic Sea (muscle, liver, kidney, lung, spleen, adipose tissue and skin) the concentrations of cadmium (Cd), lead (Pb) and arsenic (As) were analysed. In total, 186 dolphins were analysed; 155 bottlenose (Tursiops truncatus), 25 striped (Stenella coeruleoalba) and 6 Risso's dolphins (Grampus griseus). Cadmium concentrations in tissue samples ranged from 0.001 mg/kg in muscle to 16.8 mg/kg wet weight in kidney. Arsenic concentrations in dolphin samples ranged from 0.010 to 12.9 mg/kg ww. The lowest As concentration was found in spleen and highest in liver of bottlenose dolphin. Cadmium and As levels in Risso's dolphins showed higher concentrations in all tissues in comparison to bottlenose and striped dolphins. >50 % of the measured Pb values for all three species of dolphins and examined tissues were lower than 0.1 mg/kg. The accumulation of Cd and As during the lifetime was confirmed. None of the dolphins analysed in this study were exposed to concentrations of Cd in the liver higher than 20 mg/kg wet weight, which can cause renal failure in marine mammals. Numerous species of marine mammals inhabit coastal environments alongside humans and utilize similar food sources, such as fish and cephalopods. Consequently, these mammals can function as valuable indicators of public health concerns.

An operational framework for wildlife health in the One Health approach

Wildlife is an essential component of biodiversity and provides people with multiple social and economic benefits. However, a resurgence of epidemics over the past two decades has highlighted wildlife's role as a potential source of dangerous pathogens for humans and livestock, with devastating consequences worldwide. Simultaneously, numerous reports have indicated that wildlife populations are declining at an alarming rate due to human and livestock pathogens, predation, and competition. An integrated approach to managing wildlife, human, and domestic animal health is therefore clearly needed. Yet this integration often fails to materialize due to a lack of wildlife health standards and know-how. Here, we present an operational framework that follows a step-by-step approach: i) a holistic definition of human health is adapted to the context of other-than-human animals, including wildlife; then, ii) different categories of wildlife living within a landscape or a country are defined based on the management systems under which they live. For each wildlife category, the type (natural vs. anthropogenic) of habitat, the nature of the interface of wildlife with humans and/or livestock, and the level of sanitary control are defined; and finally, iii) the holistic definition of wildlife health is considered in relation to each wildlife category to define health challenges and the domains of expertise required to address them. This framework can assist national and international agencies, including veterinary and wildlife authorities and policy makers, in defining wildlife health priorities, responsibilities, policies and capacity building strategies. The extensive interdisciplinary collaboration needed to manage the many different aspects of wildlife health calls for a more integrated One Health approach.

A systematic review on global zoonotic virus-associated mortality events in marine mammals

Marine mammals play a critical role as sentinels for tracking the spread of zoonotic diseases, with viruses being the primary causative factor behind infectious disease induced mortality events. A systematic review was conducted to document marine mammal mortality events attributed to zoonotic viral infections in published literature across the globe. This rigorous search strategy yielded 2883 studies with 88 meeting inclusion criteria. The studies spanned from 1989 to 2023, with a peak in publications observed in 2020. Most of the included studies were retrospective, providing valuable insights into historical trends. The United States (U.S.) reported the highest number of mortality events followed by Spain, Italy, Brazil and the United Kingdom. Harbor seals were the most impacted species, particularly in regions like Anholt, Denmark and the New England Coast, U.S. Analysis revealed six main viruses responsible for mortality events, with Morbillivirus causing the highest proportion of deaths. Notably, the occurrence of these viral events varied geographically, with distinct patterns observed in different regions. Immunohistochemistry emerged as the most employed detection method. This study underscores the importance of global surveillance efforts in understanding and mitigating the impact of viral infections on marine mammal populations, thereby emphasizing the necessity of collaborative One Health approaches to address emerging threats at the human-animal-environment interface. Additionally, the potential transfer of zoonotic viruses to aquatic organisms used in food production, such as fish and shellfish, highlights the broader implications for food safety, food security and public health.

Comparative review of One Health and Indigenous approaches to wildlife research in Inuit Nunangat

There is increasing interest in One Health and Indigenous methodologies and approaches in wildlife research, but they are not widely used research applications in the Arctic. Both approaches are wide in scope and originate from different knowledge systems but are often compared synonymously. We review the literature of overlap between the term One Health and Inuit Qaujimajatuqangit (Inuit Indigenous Knowledge) throughout Inuit Nunaat on wildlife research. Three databases (SCOPUS, Web of Science, and BIOSIS) were used to find English language articles and books within the bounds of Inuit Nunaat. While One Health and Inuit Qaujimajatuqangit research approaches share synergies, they are fundamentally disparate owing to their differences in epistemology, including views on the natural environment and wildlife management. We describe current examples of One Health being operationalized in Inuit Nunaat and identify potential to address larger and more complex questions about wildlife health, with examples from terrestrial and marine Arctic wildlife. Both Indigenous methodologies and One Health naturally have a human component at their core, which seamlessly lends itself to discussions on wildlife management, as human actions and regulations directly impact environment and wildlife health.

Liver Lesions in Estuarine Dolphins in the Indian River Lagoon, Florida: Does Microcystin Play a Role?

Microcystin (MC), a hepatotoxin produced by cyanobacteria, was introduced into the Indian River Lagoon (IRL), Florida, in 2005 through freshwater outflows. Since then, MC has been detected in humans, domestic animals, and wildlife in the lagoon. Potential public health effects associated with MC exposure along the IRL include an increased risk of non-alcoholic liver disease among area residents. Yet, there are limited studies characterizing liver disease, as well as the potential role of MC, in humans and animals in this region. Thus, histopathology reports (n = 133) were reviewed in the stranded common bottlenose dolphin (Tursiops truncatus truncatus) (n = 156, 2005-2024) to describe liver lesions in this important IRL sentinel. Liver and fecal samples (n = 161) from stranded individuals were screened for MC via an enzyme immunoassay (ELISA). These samples were then confirmed via the 2-methyl-3-methoxy-4-phenylbutyric acid technique (MMPB) to evaluate whether liver histopathologic lesions were linked to MC exposure. Minimally invasive MC screening methods were also assessed using respiratory swabs and vapor. Inflammation (24%, n = 32), fibrosis (23%, n = 31), lipidosis/vacuolation (11%, n = 15), and necrosis (11%, n = 14) were the most common liver anomalies observed. These non-specific lesions have been reported to be associated with MC exposure in numerous species in the peer-reviewed literature. Ten bottlenose dolphins tested positive for the toxin via ELISA, including two individuals with hepatic lipidosis, but none were confirmed by MMPB. Thus, this study did not provide evidence for MC-induced liver disease in IRL bottlenose dolphins. Other causes should be considered for the lesions observed (e.g., heavy metals, metabolic disease, and endoparasites). Respiratory swabs require further validation as a pre-mortem MC screening tool in free-ranging wildlife.

Parasitic Infections in Stranded Whales and Dolphins in Canary Islands (2018-2022): An Update

The Canary Islands are considered a hot spot for marine species biodiversity. Each stranded cetacean has provided important scientific, biological and pathological information. The morphological identification of parasites in these stranded cetaceans is the main aim of the present article. An investigation to identify parasites was carried out in 233 stranded animals (2018-2022), which were submitted for necropsy. Adult and sub-adult/juvenile animals were the most parasitized age categories, and eighteen parasite species were morphologically identified, including nematodes (Crassicauda grampicola, Crassicauda anthonyi, Halocercus delphini, Anisakis simplex, Stenurus globicephalae, Stenurus ovatus), trematodes (Nasitrema delphini, Oschmarinella rochebruni, Brachycladium atlanticum, Pholeter gastrophilus), cestodes (Clistobothrium delphini, Clistobothrium grimaldii), acanthocephalans (Bolbosoma vasculosum, Bolbosoma capitatum), protists (Toxoplasma gondii) and crustaceans (Conchoderma auritum, Xenobalanus globicipitis, Pennella balaenoptera), as well as nine genera: Crassicauda sp., Halocercus sp., Anisakis sp., Stenurus sp., Nasitrema sp., Oschmarinella sp., Dyphyllobothrium sp., Cyamus sp., Conchoderma sp., and Sarcocystis sp. These could not be identified at the species level. Differences in the host specificity of some parasites were observed, varying in prevalence. The accurate morphological identification of the parasites affecting these marine mammals is essential to understanding disease epidemiology, assessing cetacean populations' health status, and developing effective conservation and management strategies.

Phthalates and fatty acid markers in free-ranging cetaceans from an insular oceanic region: Ecological niches as drivers of contamination

Plastic additives, such as phthalates, are ubiquitous contaminants that can have detrimental impacts on marine organisms and overall ecosystems' health. Valuable information about the status and resilience of marine ecosystems can be obtained through the monitoring of key indicator species, such as cetaceans. In this study, fatty acid profiles and phthalates were examined in blubber biopsies of free-ranging individuals from two delphinid species (short-finned pilot whale - Globicephala macrorhynchus, n = 45; common bottlenose dolphin - Tursiops truncatus, n = 39) off Madeira Island (NE Atlantic). This investigation aimed to explore the relations between trophic niches (epipelagic vs. mesopelagic), contamination levels, and the health status of individuals within different ecological and biological groups (defined by species, residency patterns and sex). Multivariate analysis of selected dietary fatty acids revealed a clear niche segregation between the two species. Di-n-butylphthalate (DBP), diethyl phthalate (DEP), and bis(2-ethylhexyl) phthalate (DEHP) were the most prevalent among the seven studied phthalates, with the highest concentration reached by DEHP in a bottlenose dolphin (4697.34 ± 113.45 ng/g). Phthalates esters (PAEs) concentration were higher in bottlenose dolphins (Mean ∑ PAEs: 947.56 ± 1558.34 ng/g) compared to pilot whales (Mean ∑ PAEs: 229.98 ± 158.86 ng/g). In bottlenose dolphins, DEHP was the predominant phthalate, whereas in pilot whales, DEP and DBP were more prevalent. Health markers suggested pilot whales might suffer from poorer physiological conditions than bottlenose dolphins, although high metabolic differences were seen between the two species. Phthalate levels showed no differences by ecological or biological groups, seasons, or years. This study is the first to assess the extent of plastic additive contamination in free-ranging cetaceans from a remote oceanic island system, underscoring the intricate relationship between ecological niches and contaminant exposure. Monitoring these chemicals and their potential impacts is vital to assess wild population health, inform conservation strategies, and protect critical species and habitats.

Epidemiology of marine turtle fibropapillomatosis and tumour-associated chelonid alphaherpesvirus 5 (ChHV5; Scutavirus chelonidalpha5) in North-Western Mexico: a scoping review implementing the one health approach

Fibropapillomatosis (FP) - tumour-associated chelonid alphaherpesvirus 5 (ChHV5; Scutavirus chelonidalpha5) - is a disease that affect marine turtles around the world, and characterized by the formation of cutaneous tumours that can appear anywhere on the body. We carried out a thorough literature search (from 1990 to 2024) in the feeding sites of North-western Mexico, a region that hosts important habitats for feeding, development, and reproduction for five of the seven existing sea turtle species. We found 18 reports recording a total of 32 cases of FP and/or ChHV5/Scutavirus chelonidalpha5 in coastal and insular areas of North-western Mexico. Baja California Sur resulted with the highest number of cases (75%). While the first case of ChHV5/Scutavirus chelonidalpha5 infection was reported in 2004, the presence of FP tumours was reported in 2014 and became more frequent between 2019 and 2024. The affected species were black, Chelonia mydas (50%), olive ridley, Lepidochelys olivacea (46.8%) and loggerhead turtles, Caretta caretta (3.2%). Tumours occurred mainly in anterior flippers (46.1%) and neck (22.5%), and most had a nodular and verrucous appearance with a rough surface. In the study region, there is a potential sign of the emergence of the ChHV5/Scutavirus chelonidalpha5 infections and FP disease during the last 20 years, with a rapid increase during the last 10 years. As long as infections by ChHV5/Scutavirus chelonidalpha5 and the prevalence of the FP disease may be potentially influenced by anthropogenic activities, a One Health approach is needed to understand and improve sea turtles' health.

Detection of Toxoplasma gondii in wild bivalves from the Kerguelen and Galapagos archipelagos: influence of proximity to cat populations, exposure to marine currents and kelp density

Oocysts of the protozoan Toxoplasma gondii are found in felid feces and can be washed into coastal waters, where they persist for months, attaching to algae and accumulating in invertebrates. We used wild bivalves to assess contamination of coastal waters of the Kerguelen and Galapagos archipelagos by this zoonotic parasite. Additionally, we leveraged the contrasting situations of these archipelagos to identify some potential drivers of contamination. In the Galapagos, with a cat density reaching 142 per km2, 15.38% of the sampled oysters (Saccostrea palmula) tested positive for T. gondii by quantitative real-time PCR (qPCR) (n = 260), and positive samples were found in all eight sampling sites. In Kerguelen, with 1-3 cats per km2, 40.83% of 120 tested mussels (Mytilus edulis platensis) were positive, and positive samples were found in four out of the five sampling sites. These findings provide evidence of T. gondii contamination in the coastal waters of these archipelagos. Furthermore, T. gondii-positive bivalves were found on islands located 20 km away (Galapagos) and 5 km away (Kerguelen) from the nearest cat population, indicating that T. gondii oocysts can disperse through waterborne mechanisms over several kilometers from their initial deposition site. In the Galapagos, where runoff is infrequent and all sites are exposed to currents, the prevalence of qPCR-positive bivalves did not show significant variations between sites (p = 0.107). In Kerguelen where runoff is frequent and site exposure variable, the prevalence varied significantly (p < 0.001). The detection of T. gondii in Kerguelen mussels was significantly correlated with the site exposure to currents (odds ratio (OR) 60.2, p < 0.001) and the on-site density of giant kelp forests (OR 2.624, p < 0.001). This suggests that bivalves can be contaminated not only by oocysts transported by currents but also by consuming marine aggregates containing oocysts that tend to form in kelp forests.

Contaminant Exposure and Liver and Kidney Lesions in North American River Otters in the Indian River Lagoon, Florida

The harmful algal bloom (HAB) liver toxin microcystin (MC) and trace element biomagnification were previously detected in organisms in the Indian River Lagoon (IRL), Florida. Since there are no routine screening programs for these contaminants, liver tissue from North American river otters (Lontra canadensis), an important sentinel species in the IRL, was screened for MC via enzyme-linked immunoassay (ELISA), followed by confirmatory analyses via liquid-chromatography/mass spectrometry methods (LC-MS/MS). Liver and kidney samples were evaluated for trace element (As, Cd, Co, Cu, Fe, Hg, Mn, Mo, Pb, Se, Tl, and Zn) bioaccumulation via inductively coupled plasma mass spectrometry (ICP-MS). Histopathologic evaluation of the liver and kidney was conducted to assess possible correlation with toxic insults. Forty-three river otters were evaluated (2016-2022). Microcystin was not detected in any river otter sample (n = 37). Of those tested for trace element bioaccumulation (n = 22), no sample measured above provided reference ranges or estimated toxic thresholds for this species. There were no statistically significant patterns observed based on season, year, or age class, but sex had a small influence on trace element levels in the kidney. One individual had a kidney Cu level (52 μg/g dry weight) higher than any previously reported for this species. Trace elements were detected at presumed background levels providing baselines for future monitoring. For otters with available histopathologic evaluation (n = 28), anomalies indicative of contaminant exposure (non-specific inflammation, necrosis, and/or lipidosis) were present in the liver and kidney of 18% and 4% of individuals, respectively. However, since these lesions were not linked to abnormal trace element bioaccumulation or MC exposure, other causes (e.g., infectious disease) should be considered.

Marine mammals as indicators of Anthropocene Ocean Health

The current state of marine mammal populations reflects increasing anthropogenic impacts on the global Ocean. Adopting a holistic approach towards marine mammal health, incorporating healthy individuals and healthy populations, these taxa present indicators of the health of the overall Ocean system. Their present deterioration at the animal, population and ecosystem level has implications for human health and the global system. In the Anthropocene, multiple planetary boundaries have already been exceeded, and quiet tipping points in the Ocean may present further uncertainties. Long and short-term monitoring of marine mammal health in the holistic sense is urgently required to assist in evaluating and reversing the impact on Ocean Health and aid in climate change mitigation.

Pathogen Prevalence in Cetaceans Stranded along the Italian Coastline between 2015 and 2020

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.

Current species protection does not serve its porpoise-Knowledge gaps on the impact of pressures on the Critically Endangered Baltic Proper harbour porpoise population, and future recommendations for its protection

Successful management requires information on pressures that threaten a species and areas where conservation actions are needed. The Baltic Proper harbour porpoise population was first listed as Critically Endangered by the International Union for the Conservation of Nature in 2008. Now, 16 years later, there is no change in conservation status despite ample conservation policy calling for its protection and an urgent need for management action to protect this population. Here, we provide an overview of the current status of the population, highlight knowledge gaps on the impact of pressures, and make recommendations for management of anthropogenic activities. Based on an exceeded limit for anthropogenic mortality, the high concentrations of contaminants in the Baltic Sea, combined with reductions in prey availability and increases in underwater noise, it is inferred that this population is likely still decreasing in size and conservation action becomes more urgent. As bycatch and unprotected underwater explosions result in direct mortality, they must be reduced to zero. Inputs of contaminants, waste, and existing and emerging noise sources should be minimised and regulated. Additionally, ecosystem-based sustainable management of fisheries is paramount in order to ensure prey availability, and maintain a healthy Baltic Sea. Stranding networks to routinely assess individuals for genetic population assignment and health need to be expanded, to identify rare samples from this population. Knowledge is still scarce on the population-level impact of each threat, along with the cumulative impact of multiple pressures on the population. However, the current knowledge and management instruments are sufficient to apply effective protection for the population now. While bycatch is the main pressure impacting this population, urgent conservation action is needed across all anthropogenic activities. Extinction of the Baltic Proper harbour porpoise population is a choice: decision-makers have the fate of this genetically and biologically distinct marine mammal population in their hands.

Levels of polycyclic aromatic hydrocarbons and organochlorine pesticides in sea snakes (Elapidae: Hydrophiinae) from Sharjah, United Arab Emirates

This study reports OCP and PAH concentrations in the tissues of stranded sea snakes from Sharjah, UAE. Samples from 10 Hydrophis lapemoides, 2 Hydrophis ornatus and 1 Hydrophis curtus were analyzed. Muscle, liver and fat tissues were extracted using micro-QuEChERs, followed by d-SPE and analyzed using GC/MS. Higher concentrations of OCPs were detected, while PAHs were more frequently detected. Significant correlations suggest that OCPs and PAHs do bioaccumulate in the tissues of sea snakes. Additionally, OCPs with lower log Kow (octanol-water partition coefficient) values were mainly detected in the muscle samples of H. lapemoides, whereas OCPs with higher log Kow values were more commonly present in the liver and fat samples. The concentrations of OCPs reported in this study were higher than those previously documented in other marine reptiles in the UAE or sea snakes from different geographical regions.

Intercorrelations of Chlorinated Paraffins, Dechloranes, and Legacy Persistent Organic Pollutants in 10 Species of Marine Mammals from Norway, in Light of Dietary Niche

Short-, medium-, and long-chain chlorinated paraffins (CPs) (SCCPs, MCCPs, and LCCPs) and dechloranes are chemicals of emerging concern; however, little is known of their bioaccumulative potential compared to legacy contaminants in marine mammals. Here, we analyzed SCCPs, MCCPs, LCCPs, 7 dechloranes, 4 emerging brominated flame retardants, and 64 legacy contaminants, including polychlorinated biphenyls (PCBs), in the blubber of 46 individual marine mammals, representing 10 species, from Norway. Dietary niche was modeled based on stable isotopes of nitrogen and carbon in the skin/muscle to assess the contaminant accumulation in relation to diet. SCCPs and dechlorane-602 were strongly positively correlated with legacy contaminants and highest in killer (Orcinus orca) and sperm (Physeter macrocephalus) whales (median SCCPs: 160 ng/g lw; 230 ng/g lw and median dechlorane-602: 3.8 ng/g lw; 2.0 ng/g lw, respectively). In contrast, MCCPs and LCCPs were only weakly correlated to recalcitrant legacy contaminants and were highest in common minke whales (Balaenoptera acutorostrata; median MCCPs: 480 ng/g lw and LCCPs: 240 ng/g lw). The total contaminant load in all species was dominated by PCBs and legacy chlorinated pesticides (63-98%), and MCCPs dominated the total CP load (42-68%, except 11% in the long-finned pilot whale Globicephala melas). Surprisingly, we found no relation between contaminant concentrations and dietary niche, suggesting that other large species differences may be masking effects of diet such as lifespan or biotransformation and elimination capacities. CP and dechlorane concentrations were higher than in other marine mammals from the (sub)Arctic, and they were present in a killer whale neonate, indicating bioaccumulative properties and a potential for maternal transfer in these predominantly unregulated chemicals.

Phenotypic and genotypic antimicrobial resistance patterns in honey bee (Apis mellifera L.) bacterial symbionts

Antimicrobial resistance (AMR) is a major global public health problem. Nevertheless, the knowledge of the factors driving the spread of resistance among environmental microorganisms is limited, and few studies have been performed worldwide. Honey bees (Apis mellifera L.) have long been considered bioindicators of environmental pollution and more recently also of AMR. In this study, 53 bacterial strains isolated from the body surface of honey bees at three ontogenetic stages, collected from ten different geographic locations, were tested for their phenotypic and genotypic resistance to eight classes of the most widely used antimicrobials in human and veterinary medicine. Results showed that 83% of the strains were resistant to at least one antimicrobial and 62% were multidrug-resistant bacteria, with a prevalence of resistance to nalidixic acid, cefotaxime, and aztreonam. A high percentage of isolates harbouring at least one antimicrobial gene was also observed (85%). The gene encoding resistance to colistin mcr-1 was the most abundant, followed by those for tetracycline tetM and tetC. Geographical features influenced the distribution of these traits more than bacterial species or bee stage, supporting the use of honey bee colonies and their associated bacteria as indicators to monitor environmental resistance. This approach can improve the scientific understanding of this global threat by increasing data collection capacity.

Trace element concentrations in common dolphins (Delphinus delphis) in the Celtic Seas ecoregion: Interelement relationships and effects of life history and health status

Given the increased extraction of trace elements for use by new and emerging technologies, monitoring the environmental fate and potential effects of these compounds within the aquatic environment has never been more critical. Here, hepatic trace element concentrations were assessed in a key sentinel predator, the common dolphin (Delphinus delphis), using a long-term dataset. Variation in concentrations were assessed in relation to other elements, time period, decomposition state, sex, age, total body length, sexual maturity and nutritional status, and cause of death. Additionally, mercury toxicity thresholds for evaluating risk were reviewed and employed. Concentrations of elements which bioaccumulate, THg, MeHg, Cd, and Pb, in addition to Se and V, were strongly correlated with age, and/or body length. An association was observed between Zn concentrations and disease status, with significantly higher concentrations measured in individuals that died from infectious disease, compared to other causes. Strong inter-elemental relationships were detected, namely between Hg and Se, MeHg and Se, Cd and Se, and Cu and Zn. While THg:Se molar ratio values were observed to increase with age and body length, approaching equimolarity. THg was largely comprised of inorganic Hg in older individuals, potentially bound to Se, therefore the effects from THg toxicity may possibly be less important than originally assumed. In contrast, higher MeHg:Hg ratio values were reported in juveniles, suggesting a poorer efficiency in demethylation and a higher sensitivity. The generation of data on proportions of hepatic MeHg and inorganic Hg is highly informative to both future toxicity threshold assessments within pollutant indicator assessments, and to understanding the ultimate fate of mercury in the marine web.

Verminous bronchitis and pneumonia by nasal trematodes in Greater Caribbean manatees from Puerto Rico

Five adult Greater Caribbean manatees Trichechus manatus manatus were found stranded on various coasts of Puerto Rico; 2 stranded alive and 3 stranded dead. Clinical signs observed in live-stranded manatees included emaciation, weakness, bradypnea, arrhythmia, and nasal mucus discharge. Postmortem examinations revealed serosanguinous, mucohemorrhagic, or suppurative exudate in bronchi associated with luminal adult Pulmonicola cochleotrema (range: 18-182 trematodes), accompanied by pulmonary abscesses in 2 cases. Histologically, we observed eosinophilic bronchopneumonia of varying severity (n = 4) and chronic erosive to eosinophilic tracheobronchitis (n = 4) with squamous metaplasia (n = 3) and intralesional trematodes and eggs. The trematode identity was confirmed and compared through molecular analysis for the amplified 18S rDNA fragment. Comorbidities included enteric chiorchosis (n = 5), gastric heterocheilosis (n = 4), malnutrition (n = 4), trauma related to watercraft collision (n = 3), systemic toxoplasmosis (n = 1), acute bacterial peritonitis (n = 1), and interstitial nephritis (n = 1), suggesting that immunosuppression was a predisposing factor for lower respiratory tract pulmonicolosis. Based on lesion severity, clinical signs, and the presence and absence of other findings to explain death, this condition was considered the primary cause of death in 1 manatee, a contributory cause of death in 3 manatees, and an incidental finding in 1 individual. These clinicopathological descriptions will facilitate the diagnosis and clinical management of pulmonicolosis in T. manatus, a species endangered with extinction.

Bioaccumulation of trace elements in marine mammals: New data and transplacental transfer on threatened species

Coastal areas are affected by urban, industrial and agriculture pollutants runoff, wastewater and stormwater discharges, making this environment the final repository of chemical contaminants. These contaminants have the potential to spread out to the entire food chain, impacting marine life and the quality of their habitat. In this aspect, the concept of marine mammals as bioindicators provides an approach to the degree of contamination in the environment and to the identification and management of multiple sources of contaminants. The present study analyzed several elements like As, Ba, Cd, Cr, Cu, Hg, Mn, Mo, Ni, Pb, V and Zn in liver tissue from two dolphin species: Sotalia guianensis, a near-threatened species, and the vulnerable Pontoporia blainvillei. In the study, we also investigated if dolphins (population) recorded using the heaviest urban areas have higher concentrations of contaminants in their tissues. Dolphin samples (n = 40 S. guianensis; n = 97 P. blainvillei) were collected by daily monitoring carried out by Santos Basin Beach Monitoring Project (PMP-BS), from stranded individuals found in São Paulo state. The Spearman's rank correlation showed distinct correlations in the accumulation of trace elements by both species, indicating different sources of exposure to the elements studied or distinct biochemical processes between species. Interspecific and intraspecific variations were observed, possibly related to the individual distribution and feeding habits. Correlations were observed between age and concentrations of trace elements, positive for Cd, Hg and Mo. Finally, our findings indicate high levels of Cu, Zn, and concentrations of As, V and Hg in fetuses, in particular, an analysis was performed on a fetus found inside a stranded individual, indicating placental transfer as the first route of exposure for some elements.

Antibiotic Resistance of Bacteria Isolated from Clinical Samples and Organs of Rescued Loggerhead Sea Turtles (Caretta caretta) in Southern Italy

Antimicrobial resistance affects all environments, endangering the health of numerous species, including wildlife. Increasing anthropic pressure promotes the acquisition and dissemination of antibiotic resistance by wild animals. Sea turtles, being particularly exposed, are considered sentinels and carriers of potential zoonotic pathogens and resistant strains. Therefore, this study examined the antibiotic resistance profiles of bacteria isolated from loggerhead sea turtles hospitalised in a rescue centre of Southern Italy over a 9-year period. Resistance to ceftazidime, doxycycline, enrofloxacin, flumequine, gentamicin, oxytetracycline and sulfamethoxazole-trimethoprim was evaluated for 138 strains isolated from the clinical samples or organs of 60 animals. Gram-negative families were the most isolated: Vibrionaceae were predominant, followed by Shewanellaceae, Pseudomonadaceae, Enterobacteriaceae and Morganellaceae. These last three families exhibited the highest proportion of resistance and multidrug-resistant strains. Among the three Gram-positive families isolated, Enterococcaceae were the most represented and resistant. The opportunistic behaviour of all the isolated species is particularly concerning for diseased sea turtles, especially considering their resistance to commonly utilised antibiotics. Actually, the multiple antibiotic resistance was higher when the sea turtles were previously treated. Taken together, these findings highlight the need to improve antimicrobial stewardship and monitor antibiotic resistance in wildlife, to preserve the health of endangered species, along with public and environmental health.

Metal Levels in Striped Dolphins (Stenella coeruleoalba) and Common Dolphins (Delphinus delphis) Stranded along the Sicilian Coastlines of the Mediterranean Sea

Dolphins, top predators of the aquatic food chain, are used as sentinel species of marine pollution as they are sensitive to environmental changes and able to accumulate a large content of contaminants. Several EU directives promote study of marine mammalians as bio-indicators to evaluate the presence of contaminants in the aquatic environment, such as the Mediterranean Sea, which is rich in environmental pollutants due to its geographic and geo-morphological characteristics. The aim of this study was to evaluate the content of toxic and essential metals and metalloids (Hg, Pb, Cd, As, Se and Zn), through ICP-MS analysis, in organs/tissues (liver, muscle, lung, kidney and skin) of striped dolphins (Stenella coeruleoalba) and common dolphins (Delphinus delphis) stranded along the Sicilian coastlines of the Mediterranean Sea. The results confirm the exposure of dolphins to toxic metals and metalloids, with the highest Hg levels observed in skin and liver, although a low Metal Pollution Index (MPI) was found in all samples of both dolphin species. From a comparative analysis of trace metals and metalloids according to sex and state of development, the highest levels of Cd and As were found in females vs. males and adults vs. juveniles, except for Pb in both species, and significant differences were observed between the two species, size of specimens, and organs/tissues analyzed. The highest Hg levels were correlated to those of essential metals Se and Zn, expressed as molar ratios, to evaluate the potential synergic effect of these detoxifying elements against Hg toxicity. This study confirms the rule of Stenella coeruleoalba and Delphinus delphis as valid sentinel species of the Mediterranean Sea, to verify the trend of metals pollution in this aquatic environment and, consequently, the health of these marine species.

Infrared Thermography of the Blowhole as a Potential Diagnostic Tool for Health Assessment in Killer Whales (Orcinus orca)

Killer whales (Orcinus orca) are experiencing increasing environmental pressures, with some ecotypes being identified as endangered, and the development and validation of non-invasive health assessment tools is critical for assessing the well-being of individuals within these endangered populations. Infrared thermography of the blowhole is a non-contact method of temperature measurement that was recently investigated in killer whales in managed care. Two male killer whales presenting with clinical signs at separate institutions had veterinary clinical health assessments performed, which included infrared thermography of the blowhole as well as concurrent rectal temperature measurement. The current case report is aimed at describing the clinical use of infrared thermography of the blowhole as a method to detect elevated body temperature in two killer whales. Both animals exhibited blowhole temperatures above the previously reported values (36.4 °C and 37.6 °C; the mean in healthy whales is reported to be 34.21 ± 1.47 °C) with concurrently elevated rectal temperatures, as well as clinicopathologic findings consistent with a systemic inflammatory response (e.g., neutrophilia, increased fibrinogen and erythrocyte sedimentation rate, hypoferritinemia). Following veterinary intervention, both animals' blowhole and rectal temperatures returned to baseline. Infrared thermography of the blowhole represents a promising tool for the identification of pyrexic animals and with further investigation may be considered as part of conservation health assessments for threatened free-ranging populations.

Cetacean Stranding Response Program and Spatial-Temporal Analysis in Taiwan, 1994-2018

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.

Mercury Concentrations in Two Populations of the most Endangered Dolphin (Pontoporia blainvillei) from the Southwestern Atlantic Ocean

Mercury contamination has been aggravated by emerging environmental issues, such as climate change. Top predators present concerning Hg concentrations once this metal bioaccumulates and biomagnifies. This study evaluated total mercury (THg) concentrations in tissues of 43 franciscanas (Pontoporia blainvillei) from two populations: the Franciscana Management Area (FMA) IIb and FMA IIIa. Animals from FMA IIIa showed mean concentration 5-times and 2.5-times higher in the liver and kidney (4.73 ± 6.84 and 0.52 ± 0.51 µg.g-1, w.w., respectively) than individuals from FMA IIb (0.89 ± 1.04 and 0.22 ± 0.15 µg.g-1, w.w., respectively). This might be due to: (I) individuals sampled from FMA IIIa being larger and older, and/or (II) the area near FMA IIIa presents environmental features leading to higher THg availability. Coastal contamination can affect franciscanas' health and population maintenance at different levels depending on their life history and, therefore, it should be considered to guide specific conservation actions.

PAHs in franciscana dolphins from the Southwestern Atlantic Ocean: Concentration and maternal transfer assessments

Polycyclic aromatic hydrocarbons (PAHs) are organic compounds ubiquitous in the environment and known for their toxic, mutagenic, and carcinogenic effects. These compounds can bioaccumulate in the biota and be transferred through trophic webs. The franciscana dolphin (Pontoporia blainvillei), as top predators, can be an environmental sentinels. Thus, this study aimed to provide data about PAHs concentration in their hepatic tissue collected on the coast of Espírito Santo (Franciscana Management Area, FMA Ia), Rio de Janeiro (FMA IIa), and São Paulo states (FMA IIb), in Southeastern Brazil. PAHs were detected in 86 % of franciscana dolphins (n = 50). The highest ∑PAHsTotal median concentration was reported in FMA Ia followed by FMA IIb and FMA IIa (1055.6; 523.9, and 72.1 ng.g-1 lipid weight, respectively). Phenanthrene was detected in one fetus and two neonates, showing maternal transfer of PAHs in these dolphins. Evaluating PAHs with potential toxic effects is of utmost importance for the conservation of a threatened species.

A Quantitative Analysis of Microplastics in the Gastrointestinal Tracts of Odontocetes in the Southeast Region of the United States

Microplastics (<5 mm in diameter) are ubiquitous in the oceanic environment, yet microplastic accumulation in marine mammals is vastly understudied. In recent years, efforts have been made to document microplastic profiles in odontocetes. The objective of the present study was to describe and quantify microplastics in the gastrointestinal (GI) tracts of deceased odontocetes that stranded in the southeastern United States. Our study included 24 bottlenose dolphins (Tursiops truncatus), two pygmy sperm whales (Kogia breviceps), one pantropical spotted dolphin (Stenella attenuata), one short-snouted spinner dolphin (Stenella clymene), one Risso's dolphin (Grampus griseus), and one dwarf sperm whale (Kogia sima) obtained from stranding networks in Texas, Alabama, Florida, and Puerto Rico. Contents found in the GI tracts, namely, the stomach and portions of the intestinal tract, were subjected to a laboratory procedure to isolate microplastics. The physical characteristics of microparticles were analyzed with a stereomicroscope, and microplastics were classified by polymer type via Fourier-transform infrared spectroscopy. There was an average of 47.6 ± 41.4 microparticles, ranging from 1 to 193 items per stomach. More specifically, there was an average of 5.6 ± 4.7 microplastics per stomach. The predominant morphologies, colors, and polymer types were fibers, white-colored items, and polyester, respectively. This research contributes to the current knowledge of microplastic exposure in top marine mammal predators and sets the stage for further exploration into the associated risks of microplastics in odontocetes within the United States and worldwide. Environ Toxicol Chem 2024;43:1260-1273. © 2024 SETAC.

Candida spp. in Cetaceans: Neglected Emerging Challenges in Marine Ecosystems

Cetaceans, which are crucial in marine ecosystems, act as sentinels for ecosystem and human-environmental health. However, emerging fungal infections, particularly by Candida spp., pose a growing concern in these marine mammals. This review consolidates current knowledge on the prevalence, clinical manifestations, species distribution, and antifungal resistance of Candida infections in cetaceans. We detail the diverse pathogenic impacts of Candida, including respiratory, dermal, and systemic afflictions, underscoring diagnostic and treatment challenges amid rising antifungal resistance. Our analysis extends beyond health concerns in captive cetaceans, where confinement stress heightens vulnerability, to encompass substantial ecological risks in wild populations. The review emphasizes the One Health perspective, linking cetacean health with broader environmental and human public health issues. We particularly focus on the potential zoonotic transmission of emerging fungal pathogens such as Candida auris and the role of environmental changes in fostering antifungal resistance. The study underscores the need for concerted, interdisciplinary efforts in veterinary, medical, and environmental sciences to enhance understanding and management of Candida infections in cetaceans. We advocate for comprehensive monitoring and collaborative research initiatives to mitigate the rising challenge of these infections. Addressing Candida spp. in cetaceans is not just a conservation priority but a critical step in safeguarding overall marine health and, by extension, human health in the context of evolving infectious diseases.

Endocrine-Disrupting Chemical Exposure Induces Adverse Effects on the Population Dynamics of the Indo-Pacific Humpback Dolphin

Cetaceans play a pivotal role in maintaining the ecological equilibrium of ocean ecosystems. However, their populations are under global threat from environmental contaminants. Various high levels of endocrine-disrupting chemicals (EDCs) have been detected in cetaceans from the South China Sea, such as the Indo-Pacific humpback dolphins in the Pearl River Estuary (PRE), suggesting potential health risks, while the impacts of endocrine disruptors on the dolphin population remain unclear. This study aims to synthesize the population dynamics of the humpback dolphins in the PRE and their profiles of EDC contaminants from 2005 to 2019, investigating the potential role of EDCs in the population dynamics of humpback dolphins. Our comprehensive analysis indicates a sustained decline in the PRE humpback dolphin population, posing a significant risk of extinction. Variations in sex hormones induced by EDC exposure could potentially impact birth rates, further contributing to the population decline. Anthropogenic activities consistently emerge as the most significant stressor, ranking highest in importance. Conventional EDCs demonstrate more pronounced impacts on the population compared to emerging compounds. Among the conventional pollutants, DDTs take precedence, followed by zinc and chromium. The most impactful emerging EDCs are identified as alkylphenols. Notably, as the profile of EDCs changes, the significance of conventional pollutants may give way to emerging EDCs, presenting a continued challenge to the viability of the humpback dolphin population.

Exposure of Urban European Hedgehogs (Erinaceus europaeus) to Toxoplasma gondii in Highly Populated Areas of Northeast Spain

Toxoplasma gondii is a generalist zoonotic parasite that involves a wide range of warm-blooded animals as intermediate hosts and felines as definitive hosts. Recent studies have proved significant positive associations between human population density and T. gondii seroprevalence in wildlife. However, there is limited data regarding T. gondii wildlife in urban areas, where the highest human density occurs. The present study aimed to analyse the T. gondii exposure in urban hedgehogs from the Metropolitan Area of Barcelona, NE Spain. One hundred eighteen hedgehogs were analysed for the presence of antibodies (modified agglutination test; n = 55) and parasite DNA (qPCR; heart = 34; brain = 60). Antibodies were detected in 69.09% of hedgehogs. T. gondii DNA was not detected in any of the analysed samples. The present study reports a high T. gondii seroprevalence in urban hedgehogs in areas surrounding Barcelona, the most densely human-populated area of NE Spain, reinforcing the association between human population density and environmental T. gondii oocysts. The lack of detection by molecular techniques warrants more studies. In the last few decades, the distribution and abundance of European hedgehogs have declined, including their urban populations. Further research is needed to investigate the impact of T. gondii on hedgehog populations.

Trace Elements in Stenella coeruleoalba: Assessment of Marine Environmental Pollution and Dolphin Health Status

Heavy metals are environmental contaminants and can easily accumulate and biomagnify in various marine species (fishes and mammalians) at the top of the aquatic food chain. Among marine mammalians, the striped dolphin (Stenella coeruleoalba) is the most abundant cetacean in the Mediterranean Sea and is considered to be a sentinel species to monitor the environmental marine pollution. In this study, the contents of toxic metals and metalloids (Cd, Pb, Hg, and As), micro-elements (Ni, Cr, Cu, Fe, Co, Mn, Se and Zn) and macro-elements (Na, Ca, K, Mg and P) were evaluated by ICP-MS analysis in several organs/tissues (lung, skin, muscle and liver) of Stenella coeruleoalba. The assessment of marine environmental pollution and dolphins health status was carried out through further analysis of the same specific parameters such as the metal pollution index (MPI) and coefficient of condition (K). Finally, the correlation between toxic metals and metalloids and essential micro-elements, expressed as molar ratios, was analyzed to evaluate the detoxifying ability (effectiveness) of Zn, Se and Cu. Data obtained showed the presence of toxic metals and metalloids analyzed in the Stenella coeruleoalba samples but the MPI values suggested a low environmental contamination of the Mediterranean Sea where dolphins lived. The content of micro- and macro-elements was found to be in a normal range for this species and predictive of dolphins good health status, as confirmed by the coefficient of condition K. However, the correlation between toxic and essential metals, expressed as molar ratios, showed that the following toxic metals cannot be detoxified by the essential metals: 66Zn/201Hg, 82Se/201Hg, 63Cu/201Hg and 66Zn/52Cr, 82Se/52Cr, 63Cu/52Cr. Therefore, this study highlights the key role of dolphin Stenella coeruleoalba to assess marine pollution and the importance of analyzing the complete mineral profile to evaluate the animal health status.

Variations in antimicrobial resistance genes present in the rectal faeces of seals in Scottish and Liverpool Bay coastal waters

Antibiotic resistance genes originating from human activity are considered important environmental pollutants. Wildlife species can act as sentinels for coastal environmental contamination and in this study we used qPCR array technology to investigate the variety and abundance of antimicrobial resistance genes (ARGs), mobile genetic elements (MGEs) and integrons circulating within seal populations both near to and far from large human populations located around the Scottish and northwest English coast. Rectal swabs were taken from 50 live grey seals and nine live harbour seals. Nucleic acids were stabilised upon collection, enabling extraction of sufficient quality and quantity DNA for downstream analysis. 78 ARG targets, including genes of clinical significance, four MGE targets and three integron targets were used to monitor genes within 22 sample pools. 30 ARGs were detected, as well as the integrons intl1 and intl2 and tnpA transposase. Four β-lactam, nine tetracycline, two phenicol, one trimethoprim, three aminoglycoside and ten multidrug resistance genes were detected as well as mcr-1 which confers resistance to colistin, an important drug of last resort. No sulphonamide, vancomycin, macrolide, lincosamide or streptogramin B (MLSB) resistance genes were detected. Resistance genes were detected in all sites but the highest number of ARGs (n = 29) was detected in samples derived from grey seals on the Isle of May, Scotland during the breeding season, and these genes also had the highest average abundance in relation to the 16S rRNA gene. This pilot study demonstrates the effectiveness of a culture-independent workflow for global analysis of ARGs within the microbiota of live, free-ranging, wild animals from habitats close to and remote from human habitation, and highlights seals as a valuable indicator species for monitoring the presence, abundance and land-sea transference of resistance genes within and between ecosystems.

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.

Organisation and evolution of the major histocompatibility complex class I genes in cetaceans

A quarter of marine mammals are at risk of extinction, with disease and poor habitat quality contributing to population decline. Investigation of the Major Histocompatibility Complex (MHC) provides insight into species' capacity to respond to immune and environmental challenges. The eighteen available cetacean chromosome level genomes were used to annotate MHC Class I loci, and to reconstruct the phylogenetic relationship of the described loci. The highest number of loci was observed in the striped dolphin (Stenella coeruleoalba), while the least was observed in the pygmy sperm whale (Kogia breviceps) and rough toothed dolphin (Steno bredanensis). Of the species studied, Mysticetes had the most pseudogenes. Evolutionarily, MHC Class I diverged before the speciation of cetaceans. Yet, locus one was genomically and phylogenetically similar in many species, persisting over evolutionary time. This characterisation of MHC Class I in cetaceans lays the groundwork for future population genetics and MHC expression studies.

Genomic Characterization of Listeria monocytogenes and Other Listeria Species Isolated from Sea Turtles

Listeria monocytogenes is a ubiquitous pathogen found both in the environment and food. It can cause listeriosis in a wide range of animals as well as in humans. Investigations on presence, spread and virulence are still limited to terrestrial and human environments. Embracing the One Health Approach, investigating the presence and spread of L. monocytogenes in marine ecosystems and among wildlife, would provide us with useful information for human health. This study investigated the presence of L. monocytogenes and Listeria spp. in two species of sea turtles common in the Mediterranean Sea (Caretta caretta and Chelonia mydas). A total of one hundred and sixty-four carcasses of sea turtles (C. caretta n = 161 and C. mydas n = 3) stranded along the Abruzzo, Molise, Campania, and Calabria coasts, were collected. Brain and fecal samples were taken, enriched, and cultured for the detection of Listeria spp. From the specimens collected, strains of L. monocytogenes (brain n = 1, brain and feces n = 1, multiorgan n = 1 and feces n = 1), L. innocua (feces n = 1 and brain n = 1), and L. ivanovii (brain n = 1) were isolated. Typical colonies were isolated for Whole Genome Sequencing (WGS). Virulence genes, disinfectants/metal resistance, and antimicrobial resistance were also investigated. L. monocytogenes, L. innocua, and L. ivanovii were detected in C. caretta, whilst only L. monocytogenes and L. innocua in C. mydas. Notable among the results is the lack of significant differences in gene distribution between human and sea turtle strains. Furthermore, potentially pathogenic strains of L. monocytogenes were found in sea turtles.

Broad-scale impacts of coastal mega-infrastructure project on obligatory inshore delphinids: A cautionary tale from Hong Kong

Inshore marine habitats experience considerable anthropogenic pressure, as this is where many adverse effects of human activities concentrate. In the rapidly-changing seascape of the Anthropocene, Hong Kong waters at the heart of world's fastest developing coastal region can serve as a preview-window into coastal seas of the future, with ever-growing anthropogenic footprint. Here, we quantify how large-scale coastal infrastructure projects can affect obligatory inshore cetaceans, bringing about population-level consequences that may compromise their long-term demographic viability. As a case in point, we look at the construction of world's longest sea crossing system and broad-scale demographic, social and spatial responses it has caused in a shallow-water delphinid, the Indo-Pacific humpback dolphin (Sousa chinensis). Soon after the infrastructure project began, dolphins markedly altered their home range near construction sites such that these waters no longer functioned as dolphin core areas despite the apparent presence of prey, indicating that anthropogenic impacts outweighed foraging benefits. The contraction of key habitats has in turn led individuals to interact over spatially more constricted area, reshaping their group dynamics and social network. Although there was no apparent decline in dolphin numbers that could be detected with mark-recapture estimates, adult survival rates decreased drastically from 0.960 to 0.904, the lowest estimate for these animals anywhere across the region to date, notably below the previously estimated demographic threshold of their long-term persistence (0.955). It is apparent that during an advanced stage of this coastal infrastructure project, dolphins were under a major anthropogenic pressure that, if sustained, could be detrimental to their long-term persistence as a viable demographic unit. As effective conservation of species and habitats depends on informed management decisions, this study offers a valuable lesson in environmental risk assessment, underscoring the implications of human-induced rapid environmental change on obligatory inshore delphinids-sentinels of coastal habitats that are increasingly degraded in fast-changing coastal seas.

Persistent organic pollutants and polycyclic aromatic hydrocarbons in livers of stranded Arctocephalus australis in southern Brazilian beaches

23 livers of South American fur seal (Arctocephalus australis) found stranded in southern Brazilian beaches were evaluated for Persistent Organic Pollutants (POPs) and Polycyclic Aromatic Hydrocarbons (PAHs). POPs (DDTs, mirex, eldrin, dieldrin, aldrin, isodrin, HCHs, chlordanes and PCBs) and PAHs in livers were Soxhlet extracted, analyzed and quantified using Gas Chromatography Tandem Mass Spectrometry (GC-TQMS). The main POPs found were PCBs and DDTs, totaling 81 %. Among pesticides, mirex followed DDTs, possibly due to usage in Uruguay, followed by Σdrins, ΣCHLs and ΣHCHs. Naphthalene was the major PAH found, while heavier compounds did not significantly bioaccumulate. Concentrations of POPs resembled previous findings for A. australis. Considering only juveniles, no POPs showed significant differences between sexes. Lipidic content, weight and length did not show any correlation with POP concentration. This was the first record of PAHs and PBDEs in South American fur seals, and the levels of these pollutants were relatively low.

Rapid loss of maternal immunity and increase in environmentally mediated antibody generation in urban gulls

Monitoring pathogen circulation in wildlife sentinel populations can help to understand and predict the spread of disease at the wildlife-livestock-human interface. Immobile young provide a useful target population for disease surveillance, since they can be easily captured for sampling and their levels of antibodies against infectious agents can provide an index of localized circulation. However, early-life immune responses include both maternally-derived antibodies and antibodies resulting from exposure to pathogens, and disentangling these two processes requires understanding their individual dynamics. We conducted an egg-swapping experiment in an urban-nesting sentinel seabird, the yellow-legged gull, and measured antibody levels against three pathogens of interest (avian influenza virus AIV, Toxoplasma gondii TOX, and infectious bronchitis virus IBV) across various life stages, throughout chick growth, and between nestlings raised by biological or non-biological parents. We found that levels of background circulation differed among pathogens, with AIV antibodies widely present across all life stages, TOX antibodies rarer, and IBV antibodies absent. Antibody titers declined steadily from adult through egg, nestling, and chick stages. For the two circulating pathogens, maternal antibodies declined exponentially after hatching at similar rates, but the rate of linear increase due to environmental exposure was significantly higher in the more prevalent pathogen (AIV). Differences in nestling antibody levels due to parental effects also persisted longer for AIV (25 days, vs. 14 days for TOX). Our results suggest that yellow-legged gulls can be a useful sentinel population of locally transmitted infectious agents, provided that chicks are sampled at ages when environmental exposure outweighs maternal effects.

Pharmaceutical residues in stranded dolphins in the Bay of Biscay

There is a growing concern about the presence of pharmaceuticals on the aquatic environment, while the marine environment has been much less investigated than in freshwater. Marine mammals are suitable sentinel species of the marine environment because they often feed at high trophic levels, have unique fat stores and long lifespan. Some small delphinids in particular serve as excellent sentinel species for contamination in the marine environment worldwide. To the best of our knowledge, no pharmaceuticals have been detected or reported in dolphins so far. In the present study, muscle, liver and blubber samples from three common dolphins (Delphinus delphis) and seven striped dolphins (Stenella coeruleoalba) stranded along the Basque Coast (northern Spain) were collected. A total of 95 pharmaceuticals based on detectability and predicted ability to bioaccumulate in fish were included in the liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis. At least one pharmaceutical was found in 70 % of the individuals. Only three of the 95 monitored pharmaceuticals were detected in dolphin's tissues. Very low concentrations (<1 ng/g) of orphenadrine and pizotifen were found in liver and promethazine in blubber. Herein, the gap in the knowledge regarding the study organisms and marine environments with respect to pharmaceutical pollution, which demands further research to understand if pharmaceuticals are a threat for these apex predators, is highlighted and discussed.

Trace element bioaccumulation, tissue distribution, and elimination in odontocetes stranded in Florida and Georgia, USA over a 15-year period (2007-2021)

Odontocetes obtain nutrients including essential elements through their diet and are exposed to heavy metal contaminants via ingestion of contaminated prey. We evaluated the prevalence, concentration, and tissue distribution of essential and non-essential trace elements, including heavy metal toxicants, in tissue (blubber, kidney, liver, skeletal muscle, skin) and fecal samples collected from 90 odontocetes, representing nine species, that stranded in Georgia and Florida, USA during 2007-2021. Samples were analyzed for concentrations of seven essential (cobalt, copper, iron, manganese, molybdenum, selenium, zinc) and five non-essential (arsenic, cadmium, lead, mercury, thallium) elemental analytes using inductively-coupled plasma mass spectrometry. Risso's dolphins (Grampus griseus) and short-finned pilot whales (Globicephala macrorhynchus) had the highest median concentrations of mercury, cadmium, and lead, while dwarf sperm whales (Kogia sima) had the lowest. Adult pygmy and dwarf sperm whales that stranded in 2019-2021 had higher concentrations of arsenic, copper, iron, lead, manganese, selenium, thallium, and zinc compared to those that stranded in 2010-2018, suggesting an increasing risk of exposure over time. The highest concentrations of many elements (e.g., cadmium, cobalt, copper, manganese, molybdenum, thallium, zinc) were in fecal samples, illustrating the usefulness of this noninvasively collected sample. Aside from fecal samples, hepatic tissues had the highest concentrations of iron, manganese, mercury, molybdenum, and selenium in most species; renal tissues had the highest concentrations of cadmium; skin had the highest concentrations of zinc; and copper, arsenic, and lead concentrations were primarily distributed among the liver and kidneys. Phylogenetic differences in patterns of trace element concentrations likely reflect species-specific differences in diet, trophic level, and feeding strategies, while heterogeneous distributions of elemental analytes among different organ types reflect differences in elemental biotransformation, elimination, and storage. This study illustrates the importance of monitoring toxic contaminants in stranded odontocetes, which serve as important sentinels of environmental contamination, and whose health may be linked to human health.

Prevalence of Toxoplasma gondii in Wild American Mink (Neogale vison): The First Serological Study in Germany and Poland

Toxoplasma gondii is an obligate intracellular protozoan that causes toxoplasmosis in warm-blooded animals. Although most infections in humans and animals are subclinical, an infection can nevertheless be fatal. One of the important characteristics in the epidemiology of this parasite is waterborne transmission. The American mink (Neogale vison), a mammal closely adapted to freshwater ecosystems, is a potential sentinel for T. gondii. We analysed meat juice from the heart of 194 wild minks collected between 2019 and 2022 in five study areas from Germany and Poland and tested for the presence of antibodies against T. gondii. The analysis was performed using a commercial enzyme-linked immunosorbent assay test (ELISA). Antibodies were detected in 45.36% (88/194, 95% confidence interval (CI): 38.39-52.41%) of the analysed animals. While the prevalence values ranged from 37.50% to 49.30%, there was no significant difference in seroprevalence between the study areas. Juveniles were less likely to carry T. gondii antibodies than adults (odds ratio: 0.216), whereas there was no significant difference in prevalence between the sexes (odds ratio: 0.933). The results of our study show that contact with T. gondii is widespread in minks, and the parasite is common in inland freshwater ecosystems in Germany and Poland. This indicates that watercourses play an important role in the spread of T. gondii oocysts.

Closing the Organofluorine Mass Balance in Marine Mammals Using Suspect Screening and Machine Learning-Based Quantification

High-resolution mass spectrometry (HRMS)-based suspect and nontarget screening has identified a growing number of novel per- and polyfluoroalkyl substances (PFASs) in the environment. However, without analytical standards, the fraction of overall PFAS exposure accounted for by these suspects remains ambiguous. Fortunately, recent developments in ionization efficiency (IE) prediction using machine learning offer the possibility to quantify suspects lacking analytical standards. In the present work, a gradient boosted tree-based model for predicting log IE in negative mode was trained and then validated using 33 PFAS standards. The root-mean-square errors were 0.79 (for the entire test set) and 0.29 (for the 7 PFASs in the test set) log IE units. Thereafter, the model was applied to samples of liver from pilot whales (n = 5; East Greenland) and white beaked dolphins (n = 5, West Greenland; n = 3, Sweden) which contained a significant fraction (up to 70%) of unidentified organofluorine and 35 unquantified suspect PFASs (confidence level 2-4). IE-based quantification reduced the fraction of unidentified extractable organofluorine to 0-27%, demonstrating the utility of the method for closing the fluorine mass balance in the absence of analytical standards.

Survey of selected viral agents (herpesvirus, adenovirus and hepatitis E virus) in liver and lung samples of cetaceans, Brazil

Hepatic and pulmonary lesions are common in cetaceans, despite their poorly understood viral etiology. Herpesviruses (HV), adenoviruses (AdV) and hepatitis E virus (HEV) are emerging agents in cetaceans, associated with liver and/or pulmonary damage in mammals. We isolated and molecularly tested DNA for HV and AdV (n = 218 individuals; 187 liver and 108 lung samples) and RNA for HEV (n = 147 animals; 147 liver samples) from six cetacean families. All animals stranded or were bycaught in Brazil between 2001 and 2021. Positive-animals were analyzed by histopathology. Statistical analyses assessed if the prevalence of viral infection could be associated with the variables: species, family, habitat, region, sex, and age group. All samples were negative for AdV and HEV. Overall, 8.7% (19/218) of the cetaceans were HV-positive (4.8% [9/187] liver and 11.1% [12/108] lung), without HV-associated lesions. HV-prevalence was statistically significant higher in Pontoporiidae (19.2%, 10/52) when compared to Delphinidae (4.1%, 5/121), and in southeastern (17.1%, 13/76)-the most industrialized Brazilian region-when compared to the northeastern region (2.4%, 3/126). This study broadens the herpesvirus host range in cetaceans, including its description in pygmy sperm whales (Kogia breviceps) and humpback whales (Megaptera novaeangliae). Further studies must elucidate herpesvirus drivers in cetaceans.

High resolution visualisation of tiemannite microparticles, essential in the detoxification process of mercury in marine mammals

The North Sea is an ecologically rich habitat for marine wildlife which has also been impacted by industrial developments and anthropogenic emissions of contaminants such as mercury. Marine mammals are particularly susceptible to mercury exposure, due to their trophic position, long lifespan, and dependence on (increasingly contaminated) aquatic prey species. To mitigate impact, marine mammals can detoxify methylmercury by binding it to selenium-containing biomolecules, creating insoluble mercury selenide granules. Here, liver, kidney, muscle, and brain samples from an adult male bottlenose dolphin (Tursiops truncatus) with known elevated mercury concentrations were analysed through scanning electron microscopy (SEM). Tiemannite (HgSe) deposits were identified in all organs, ranging from 400 nm to 5 μm in diameter, with particle size being organ-dependent. Although reported in other studies, this is the first time that the three-dimensional nature of tiemannite is captured in marine mammal tissue.

Survival and adaptation of Streptococcus phocae in host environments

Marine mammals are sentinel species representing the "health" of our oceans on which we are dependent. There are many threats to marine mammals including infectious diseases that increase with climate change and pollution of the marine environment. Streptococcus phocae has frequently been isolated from diseased or dead marine mammals. However, its pathogenicity and contribution to disease in marine mammals is still unknown. As bacteria including (potential) pathogens has to deal with different host environments during colonization or infection, we investigated the survival of S. phocae in fresh porcine and phocid blood, in seawater and in the presence of macrophages and (epithelial) cells from harbor seals and pigs. Furthermore, we tested adherence on and invasion of different (marine) mammalian cells by S. phocae. Our results showed that S. phocae can survive in seawater for at least 11 and 28 days at 16°C and 4°C, respectively. It is able to grow in blood of harbor and grey seals, but not in porcine blood. Furthermore, S. phocae is adherent and invasive to cells from seals and pigs, while the portion of invasive cells was higher in seal derived cells. Macrophages of harbor seals were more efficient in killing S. phocae than porcine macrophages. Our results indicate that S. phocae has strategies enabling it to adapt to the marine environment and seal hosts.

The Ecology of Non-Candida Yeasts and Dimorphic Fungi in Cetaceans: From Pathogenicity to Environmental and Global Health Implications

Cetaceans, which are integral to marine ecosystems, face escalating anthropogenic threats, including climate change and pollution, positioning them as critical sentinel species for ocean and human health. This review explores the neglected realm of non-Candida yeasts in cetaceans, addressing the gaps in the understanding of their prevalence, pathogenicity, and environmental impacts. By examining identified species such as Cryptococcus spp., Paracoccidioides spp., and several dimorphic fungi, this review emphasizes global prevalence, epidemiology and ecology, pathogenicity, and potential zoonotic implications. It also discusses the fine line between yeast commensalism and pathogenicity by considering environmental influences such as pollution, climate shifts, and immune suppression. Environmental impact discussions delve into how rising ocean temperatures and pollution can modify yeast mycobiota, potentially affecting marine host health and broader ecosystem dynamics. The cetacean's unique physiology and ecological niches are considered, highlighting potential impacts on behaviors, reproductive success, and survival rates. Identifying crucial knowledge gaps, the review calls for intensified research efforts, employing advanced molecular techniques to unravel the cetacean mycobiome. Systematic studies on yeast diversity, antifungal susceptibility, and their influence on environmental and ecosystem health are proposed, and the balance between commensal and pathogenic species emphasizes the significance of the One Health approach. In conclusion, as marine mammals face unprecedented challenges, unveiling non-Candida yeasts in cetaceans emerges as a critical endeavor with far-reaching implications for the conservation of marine ecosystems and for both animal and human public health.

Hepatic concentrations of per- and polyfluoroalkyl substances (PFAS) in dolphins from south-east Australia: Highest reported globally

Per- and polyfluoroalkyl substances (PFAS) concentrations were investigated in hepatic tissue of four dolphin species stranded along the south-east coast of Australia between 2006 and 2021; Burrunan dolphin (Tursiops australis), common bottlenose dolphin (Tursiops truncatus), Indo-Pacific bottlenose dolphin (Tursiops aduncus), and short-beaked common dolphin (Delphinus delphis). Two Burrunan dolphin populations represented in the dataset have the highest reported global population concentrations of ∑25PFAS (Port Phillip Bay median 9750 ng/g ww, n = 3, and Gippsland Lakes median 3560 ng/g ww, n = 8), which were 50-100 times higher than the other species reported here; common bottlenose dolphin (50 ng/g ww, n = 9), Indo-Pacific bottlenose dolphin (80 ng/g ww, n = 1), and short-beaked common dolphin (61 ng/g ww, n = 12). Also included in the results is the highest reported individual ∑25PFAS (19,500 ng/g ww) and PFOS (18,700 ng/g ww) concentrations, at almost 30 % higher than any other Cetacea reported globally. Perfluorooctane sulfonate (PFOS) was above method reporting limits for all samples (range; 5.3-18,700 ng/g ww), and constituted the highest contribution to overall ∑PFAS burdens with between 47 % and 99 % of the profile across the dataset. The concentrations of PFOS exceed published tentative critical concentrations (677-775 ng/g) in 42 % of all dolphins and 90 % of the critically endangered Burrunan dolphin. This research reports for the first time novel and emerging PFASs such as 6:2 Cl-PFESA, PFMPA, PFEECH and FBSA in marine mammals of the southern hemisphere, with high detection rates across the dataset. It is the first study to show the occurrence of PFAS in the tissues of multiple species of Cetacea from the Australasian region, demonstrating high global concentrations for inshore dolphins. Finally, it provides key baseline knowledge to the potential exposure and bioaccumulation of PFAS compounds within the coastal environment of south-east Australia.

Legacy and emerging contaminants in marine mammals from Argentina

Marine mammals are recognized sentinels of ecosystem health. They are susceptible to the accumulation and biomagnification of pollutants, which constitute one of the greatest threats to their survival. Legacy, such as organochlorine pesticides, and emerging contaminants, like microplastics and pharmaceuticals, may have effects on marine mammals' health at individual and population levels. Therefore, the evaluation of the risks associated with pollutants in this group is of great importance. The aim of this review is to provide information on the occurrence of legacy and emerging contaminants in marine mammals that inhabit Argentine waters. Also, to identify knowledge gaps and suggest best practices for future research. Reports of legacy contaminants referring to organochlorine pesticides and polychlorinated biphenyls were found in five species of cetaceans and two of pinnipeds. With respect to emerging pollutants, the presence of plastics was only evaluated in three species. Reported data was from at least a decade ago. Therefore, it is necessary to update existing information and conduct continuous monitoring to assess temporary trends in pollutants. All the studies were carried out in the province of Buenos Aires and Northern Patagonia indicating a knowledge gap in the southern zone of the Argentine Sea. In addition, pollutants of global environmental concern that have not been studied in Argentina are discussed. Future studies should fill these gaps and a greater effort to understand the relationships between pollutants and their effects on marine mammals is suggested. This issue will make it possible to determine thresholds for all the substances and species evaluated in order to carry out more detailed risk assessments and make decisions for the conservation of marine mammals in Argentine waters.

The first report of Listeria monocytogenes detected in pinnipeds

The aim of this study was to describe the pathology in seals from which Listeria monocytogenes was isolated and investigate if the lesions' nature and severity were related to the phylogeny of isolates. L. monocytogenes was isolated from 13 of 50 (26%) dead grey seal (Halichoerus grypus) pups, six (12%) in systemic distribution, on the Isle of May, Scotland. Similar fatal L. monocytogenes-associated infections were found in a grey seal pup from Carnoustie, Scotland, and a juvenile harbour seal (Phoca vitulina) in the Netherlands. Whole genome sequencing of 15 of the L. monocytogenes isolates identified 13 multilocus sequence types belonging to the L. monocytogenes lineages I and II, but with scant phenotypic and genotypic antimicrobial resistance and limited variation in virulence factors. The phylogenetic diversity present suggests there are multiple sources of L. monocytogenes, even for seal pups born in the same colony and breeding season. This is the first description of L. monocytogenes isolated from, and detected in lesions in, pinnipeds and indicates that infection can be systemic and fatal. Therefore, listeriosis may be an emerging or overlooked disease in seals with infection originating from contamination of the marine environment.