Marine mammals as sentinel species for oceans and human health

Assessing of the use of proteins A, G, and chimeric protein AG to detect marine mammal immunoglobulins

In recent years, there has been an increase in infectious diseases in marine mammals, including brucellosis, infections of morbillivirus, herpesvirus, and poxvirus. Several serological diagnostic methods, including enzyme-linked immunosorbent assays, immunofluorescence assays (ELISA), and western blotting, have been used to detect antibodies against pathogens in marine mammals. However, options for commercial secondary antibodies used to detect antibodies in marine mammals are limited; therefore, the use of proteins A, G, or chimeric protein AG may provide a suitable alternative. This study aimed to assess the use of proteins A, G, and chimeric protein AG to detect marine mammal immunoglobulins. Currently, there are no comparative studies on the use of proteins A, G, and chimeric protein AG for the detection of immunoglobulins in marine mammals. In this study, we used ten pinnipeds' species (Baikal seal, California sea lion, harbor seal, northern fur seal, ringed seal, South American fur seal, South American sea lion, spotted seal, Steller sea lion, and walrus) and five cetacean species (beluga whale, bottlenose dolphin, harbor porpoise, killer whale, and Pacific white-sided dolphin) and compare binding ability to proteins A, G, or chimeric protein AG by ELISA. The results revealed that the immunoglobulins from pinniped and cetacean species reacted more strongly to protein A than protein G. In addition, the immunoglobulins of pinnipeds and cetaceans showed a strong binding ability to chimeric protein AG. These results suggest that proteins A, G, and chimeric protein AG would be used to help further develop serological assays.

Plastic ingestion by two cetacean groups: Ziphiidae and Delphinidae

The presence of plastic in our environment is having a massive impact on today's marine biota. Whales and dolphins are becoming sentinels of litter pollution as plastic entanglement and ingestion affect them with unknown consequences. Although information exists about this anthropogenic interaction, the compilation of this data on metastudies is difficult due to the use of varied methodologies. A combination of our own data as well as a review of historical data was used to complete an extensive study of how cetaceans are interacting with macro and micro-litter at a global level. Here, we identify the plastic uptake by two cetacean families: Ziphiidae and Delphinidae, thus allowing for a better understanding in order to offer a global overview of their current status. Additionally, analysis was run on the plastic found in the digestive contents of stranded specimens of two Cuvier's beaked whales and fourteen striped dolphins in the Alboran Sea, in the Western Mediterranean, a hotspot for marine megafauna. Out of 623 stranded cetaceans from datasets, beaked whales displayed the highest concentration of macro, meso and microplastic in the Western Pacific Ocean. Regarding striped dolphins, Eastern Spain was the location with the highest plastic ingestion. Moreover, deep divers such as beaked whales ingested more plastic than striped dolphins which could be as a consequence of their feeding behavior or habitat. Thus, this overview provides useful information concerning conservation issues on how cetacean hotspots are highly affected by marine plastic ingestion.

Viral skin diseases in odontocete cetaceans: gross, histopathological, and molecular characterization of selected pathogens

Fifty-five skin lesions from 31 stranded cetaceans along the Canary coasts (2011-2021) were submitted to macroscopic, histological, and molecular analyses to confirm infection by cetacean poxvirus, herpesvirus and cetacean morbillivirus. They were macroscopically categorized into eight categories with respective subcategories according to their color, shape, size, and consistency. Cetacean poxvirus was detected in 54.54% of the skin lesions through real-time and conventional PCRs based on the DNA polymerase gene. Additionally, herpesvirus and morbillivirus were currently detected from 43.63 and 1.82% of the cutaneous lesions, respectively. Coinfection of poxvirus and herpesvirus was detected in nine of them (16.36%), which makes the present study the first to report coinfection by both pathogens in skin lesions in cetaceans. A plausible approach to histopathological characterization of poxvirus-and herpesvirus-positive skin lesions was established. Hyperkeratosis, acanthosis, ballooning degeneration, and intracytoplasmic inclusion bodies in vacuolized keratinocytes through the stratum spinosum were common findings in poxvirus skin lesions. Alphaherpesvirus was associated with a prominent acanthotic epidermis, moderate necrosis, multifocal dyskeratosis, and irregular keratinocytes with both cellular and nuclei pleomorphism. The common histopathological findings of both pathogens were observed in coinfection lesions. However, those associated with herpesvirus were considerably more remarkable. Relationships between molecular and microscopic findings were observed for the lesions that showed tattoo-like and tortuous patterns. Further multidisciplinary diagnostic studies of infected skin lesions are needed to understand the epidemiology of these emerging infectious diseases.

Impact of per- and polyfluorinated alkyl substances (PFAS) on the marine environment: Raising awareness, challenges, legislation, and mitigation approaches under the One Health concept

Per- and polyfluorinated alkyl substances (PFAS) have long been known for their detrimental effects on the ecosystems and living organisms; however the long-term impact on the marine environment is still insufficiently recognized. Based on PFAS persistence and bioaccumulation in the complex marine food network, adverse effects will be exacerbated by global processes such as climate change and synergies with other pollutants, like microplastics. The range of fluorochemicals currently included in the PFAS umbrella has significantly expanded due to the updated OECD definition, raising new concerns about their poorly understood dynamics and negative effects on the ocean wildlife and human health. Mitigation challenges and approaches, including biodegradation and currently studied materials for PFAS environmental removal are proposed here, highlighting the importance of ongoing monitoring and bridging research gaps. The PFAS EU regulations, good practices and legal frameworks are discussed, with emphasis on recommendations for improving marine ecosystem management.

Exploring microplastic contamination in Guiana dolphins (Sotalia guianensis): Insights into plastic pollution in the southwestern tropical Atlantic

Marine mammals are considered sentinel species and may act as indicators of ocean health. Plastic residues are widely distributed in the oceans and are recognised as hazardous contaminants, and once ingested can cause several adverse effects on wildlife. This study aimed to identify and characterise plastic ingestion in the Guiana dolphins (Sotalia guianensis) from the Southwestern Tropical Atlantic by evaluating the stomach contents of stranded individuals through KOH digestion and identification of subsample of particles by LDIR Chemical Imaging System. Most of the individuals were contaminated, and the most common polymers identified were PU, PET and EVA. Microplastics were more prevalent than larger plastic particles (meso- and macroplastics). Smaller particles were detected during the rainy seasons. Moreover, there was a positive correlation between the stomach content mass and the number of microplastics, suggesting contamination through trophic transfer.

Metal-specific biomagnification and trophic dilution in the coastal foodweb of the California sea lion (Zalophus californianus) off Bahía Magdalena, Mexico: The role of the benthic-pelagic foodweb in the trophic transfer of trace and toxic metals

Trace metals concentrations along with stable isotopes ratios were measured in marine algae, sea grass, sponges, echinoderms, mollusks, crustaceans, fishes, and the California sea lion, to assess the bioaccumulation potential and detect potential risks for top predators off Bahia Magdalena, Mexico. We assessed the trophic magnification factor (TMF) to determine the potential for biomagnification of 11 trace metals. The concentrations of Fe and Zn were one order of magnitude higher than all other metals. Concentrations of As, Cu, Cd, Co, Cr, Fe, Mn and Ni correlated negatively with trophic level, supporting trophic dilution (TMF < 1, p > 0.05), while Zn and Hg had significant trophic magnification (TMF > 1, p < 0.05) when assessing only the benthic-pelagic foodweb. This research provides a baseline concentration of metals in multiple species, metal-specific foodweb bioaccumulation and biomagnification of mercury, underscoring the key role of the macrobenthic community as biovectors for trophic transfer of Hg through the foodweb to the California sea lion.

Causes of death and pathogen prevalence in bottlenose dolphins Tursiops truncatus stranded in Alabama, USA, between 2015 and 2020, following the Deepwater Horizon oil spill

Between 2010 and 2014, an unusual mortality event (UME) involving bottlenose dolphins Tursiops truncatus occurred in the northern Gulf of Mexico, associated with the Deepwater Horizon oil spill (DWHOS). Cause of death (COD) patterns in bottlenose dolphins since then have not been analyzed, and baseline prevalence data for Brucella ceti and cetacean morbillivirus, 2 pathogens previously reported in this region, are lacking. We analyzed records from bottlenose dolphins stranded in Alabama from 2015 to 2020 with necropsy and histological findings to determine COD (n = 108). This period included another UME in 2019 associated with prolonged freshwater exposure. A subset of individuals that stranded during this period were selected for molecular testing for Brucella spp. and Morbillivirus spp. Causes of death for all age classes were grouped into 6 categories, including (1) human interaction, (2) infectious disease, (3) noninfectious disease (prolonged freshwater exposure and degenerative), (4) trauma, (5) multifactorial, and (6) unknown. Two additional categories unique to perinates included fetal distress and in utero pneumonia. Human interaction was the most common primary COD (19.4%) followed closely by infectious disease (17.6%) and noninfectious disease (freshwater exposure; 13.9%). Brucella was detected in 18.4% of the 98 animals tested, but morbillivirus was not detected in any of the 66 animals tested. Brucella was detected in some moderately to severely decomposed carcasses, indicating that it may be beneficial to test a broad condition range of stranded animals. This study provides valuable information on COD in bottlenose dolphins in Alabama following the DWHOS and is the first to examine baseline prevalence of 2 common pathogens in stranded animals from this region.

Gut bacterial communities in Atlantic bottlenose dolphins (Tursiops truncatus) throughout a disease-driven (Morbillivirus) unusual mortality event

Gut microbiomes are important determinants of animal health. In sentinel marine mammals where animal and ocean health are connected, microbiome impacts can scale to ecosystem-level importance. Mass mortality events affect cetacean populations worldwide, yet little is known about the contributory role of their gut bacterial communities to disease susceptibility and progression. Here, we characterized bacterial communities from fecal samples of common bottlenose dolphins, Tursiops truncatus, across an unusual mortality event (UME) caused by dolphin Morbillivirus (DMV). 16S rRNA gene sequence analysis revealed similar diversity and structure of bacterial communities in individuals stranding before, during, and after the 2013-2015 Mid-Atlantic Bottlenose Dolphin UME and these trends held in a subset of dolphins tested by PCR for DMV infection. Fine-scale shifts related to the UME were not common (10 of 968 bacterial taxa) though potential biomarkers for health monitoring were identified within the complex bacterial communities. Accordingly, acute DMV infection was not associated with a distinct gut bacterial community signature in T. truncatus. However, temporal stratification of DMV-positive dolphins did reveal changes in bacterial community composition between early and late outbreak periods, suggesting that gut community disruptions may be amplified by the indirect effects of accumulating health burdens associated with chronic morbidity.

Brucella ceti Infection in Striped Dolphins from Italian Seas: Associated Lesions and Epidemiological Data

Brucella ceti infections have been increasingly reported in cetaceans. In this study, we analyzed all cases of B. ceti infection detected in striped dolphins stranded along the Italian coastline between 2012 and 2021 (N = 24). We focused on the pathogenic role of B. ceti through detailed pathological studies, and ad hoc microbiological, biomolecular, and serological investigations, coupled with a comparative genomic analysis of the strains. Neurobrucellosis was observed in 20 animals. The primary histopathologic features included non-suppurative meningoencephalitis (N = 9), meningitis (N = 6), and meningoencephalomyelitis (N = 5), which was also associated with typical lesions in other tissues (N = 8). Co-infections were detected in more than half of the cases, mostly involving Cetacean Morbillivirus (CeMV). The 24 B. ceti isolates were assigned primarily to sequence type 26 (ST26) (N = 21) and, in a few cases, ST49 (N = 3). The multilocus sequence typing (cgMLST) based on whole genome sequencing (WGS) data showed that strains from Italy clustered into four genetically distinct clades. Plotting these clades onto a geographic map suggests a link between their phylogeny and the topographical distribution. These results support the role of B. ceti as a primary neurotropic pathogen for striped dolphins and highlight the utility of WGS data in understanding the evolution of this emerging pathogen.

Establishment and characterization of a novel kidney cell line derived from the common bottlenose dolphin

Common bottlenose dolphin (Tursiops truncatus) is a well-known cetacean species that inhabits temperate and tropical seas worldwide. Limited supply and poor quality of samples hinder the investigation of the effects of various pathogens and environmental pollutants on this cetacean species. Cultured cells are useful for experimental studies; however, no cell lines derived from cetaceans are generally available. Therefore, in this study, we established a novel kidney cell line, TK-ST, derived from T. truncatus. Primary cells exhibited the morphological characteristics of epithelial and fibroblast cells, but their immortalization and passaging resulted in a predominantly epithelial cell morphology. TK-ST was immortalized using the large T SV40 antigen and human telomerase reverse transcriptase and exhibited long-term stable cell growth. TK-ST cells are generally cultured in Dulbecco's modified Eagle's medium with 10% fetal bovine serum at 37°C and 5% CO2 but can also be cultured in 5-20% fetal bovine serum and several other classical media commonly used for common animal cell culture. TK-ST cells were found to be susceptible to several viruses, including the dolphin morbillivirus (most important virus in cetaceans), and exhibited cytopathic effects, facilitating the replication of the dolphin morbillivirus. Furthermore, mRNA expression levels of cytokine genes were increased in TK-ST cells after stimulation with lipopolysaccharides and poly(I:C). Therefore, the novel TK-ST cell line derived in this study can potentially be used for further in vitro studies on cetaceans.

Identification of key features relating to the coexistence mechanisms of trace elements and per- and polyfluoroalkyl substances (PFASs) in marine mammals

Organic and inorganic substances coexist in the livers of marine mammals and may correlate with one another; however, their coexistence mechanisms and relevant key features remain largely unknown. In this study, temporal variations (2011-2021) in the concentrations of nine trace elements and 19 per- and polyfluoroalkyl substances (PFASs) in the livers of Indo-Pacific humpback dolphins (Sousa chinensis) and finless porpoises (Neophocaena phocaenoides) were investigated. Interannual Cd in dolphins increased significantly whereas Pb concentrations decreased over the past decade (p < 0.05). Interannual levels of seven and four PFASs in dolphins and porpoises decreased significantly with time (p < 0.05). By further extending the timescale to 1993-2021, the sensitivity of trace elements to annual change further increased, whereas the sensitivity of PFASs remained relatively stable. Cu levels, similar to the majority of PFASs, were negatively correlated with the body length of the studied cetaceans, which led to positive correlations of Cu with six long-chain perfluoroalkyl carboxylic acids, perfluorodecane sulfonic acid, and perfluoroethylcyclohexane sulfonic acid. The concentrations of trace elements in the cetacean liver were closely correlated with cetacean sex, species, and body length, whereas PFAS concentration was responsive to time-related features such as stranded season and year. By further employing a machine learning method, we demonstrated that body length and a time-related factor (year) played a crucial role in predicting the concentrations of certain trace elements and PFASs, respectively, particularly Cu and perfluoroheptanoic acid.

A heavy burden: Metal exposure across the land-ocean continuum in an adaptable carnivore

Urbanisation and associated anthropogenic activities release large quantities of toxic metals and metalloids into the environment, where they may bioaccumulate and threaten both wildlife and human health. In highly transformed landscapes, terrestrial carnivores may be at increased risk of exposure through biomagnification. We quantified metallic element and metalloid exposure in blood of caracals (Caracal caracal), an adaptable felid inhabiting the rapidly urbanising, coastal metropole of Cape Town, South Africa. Using redundancy analysis and mixed-effect models, we explored the influence of demography, landscape use, and diet on the concentration of 11 metals and metalloids. Although species-specific toxic thresholds are lacking, arsenic (As) and chromium (Cr) were present at potentially sublethal levels in several individuals. Increased use of human-transformed landscapes, particularly urban areas, roads, and vineyards, was significantly associated with increased exposure to aluminium (Al), cobalt (Co) and lead (Pb). Foraging closer to the coast and within aquatic food webs was associated with increased levels of mercury (Hg), selenium (Se) and arsenic, where regular predation on seabirds and waterbirds likely facilitates transfer of metals from aquatic to terrestrial food webs. Further, several elements were linked to lower haemoglobin levels (chromium, mercury, manganese, and zinc) and elevated levels of infection-fighting cells (mercury and selenium). Our results highlight the importance of anthropogenic activities as major environmental sources of metal contamination in terrestrial wildlife, including exposure across the land-ocean continuum. These findings contribute towards the growing evidence suggesting cities are particularly toxic areas for wildlife. Co-exposure to a suite of metal pollutants may threaten the long-term health and persistence of Cape Town's caracal population in unexpected ways, particularly when interacting with additional known pollutant and pathogen exposure. The caracal is a valuable sentinel for assessing metal exposure and can be used in pollution monitoring programmes to mitigate exposure and promote biodiversity conservation in human-dominated landscapes.

Cetaceans as Bioindicators to Assess Alkylphenol Exposure and Hormone-Disrupting Effects in the South China Sea

Alkylphenols (APs) represent one of the highest exposure levels among endocrine disrupting chemicals (EDCs) in the South China Sea (SCS) due to their extensive use as plastic additives. The concerns about EDCs, including APs, have been reiterated since the surge in plastic waste from the COVID-19 response, but far less is known about the response of AP loadings in the SCS to emerging public policies and activities, including the COVID-19 pandemic. Here, we used cetaceans as bioindicators for monitoring two major APs, 4-nonylphenol (4-NP) and 4-tert-octylphenol (4-t-OP), in nine stranded cetacean species (n = 110) in the SCS between 2004 and 2021. Prior to the COVID-19, APs loads showed decreasing temporal trends for finless porpoises and humpback dolphins, most likely due to China's restrictions on AP use or a shift in dominant prey species. Unexpectedly, AP loads continued to decline after the COVID-19 outbreak, probably due to a temporal-lag response of marine AP fluxes to the pandemic. The health risk assessments based on hormone biomarkers and toxicity thresholds suggest the potential adverse effects of APs on cetaceans, while recent declines in APs, though limited, may mitigate the detrimental impacts.

High aluminum content in bone of marine mammals and its relation with source levels and origin

Although aluminum is widely distributed in the earth's crust, its environmental availability and wildlife assimilation rates are only partially known. Here we analyze aluminum concentrations in bone from 10 species of marine mammals inhabiting 3 geographic areas subject to different aluminum inputs: the Río de la Plata estuary (Uruguay), the coastal waters of Mauritania and the Galapagos archipelago (Ecuador). Overall, concentrations were unusually high as compared to those of terrestrial animals, with lowest concentrations in the Galapagos archipelago, then the Río de la Plata estuary and finally Mauritania. The aluminum source varied between regions, prevailing anthropogenic sources in the Río de la Plata Estuary and natural sources (wind-blown dust) in Mauritanian waters. The type of source determined contamination levels: anthropogenic sources were most significant for coastal species and showed a decline with distance of habitat from shoreline, while natural sources had a higher influence on open waters because of the dearth of biogenic silica that eliminates aluminum from the water column. Since aluminum remains in bone for several decades, marine mammal bone reflects historical levels of aluminum and therefore is a good bioindicator of the aluminum concentration of the marine environment.

Bone mineral density and microarchitecture change during skeletal growth in harbor seals (Phoca vitulina) from the German coast

Across species, the skeletal system shares mutual functions, including the protection of inner organs, structural basis for locomotion, and acting as an endocrine organ, thus being of pivotal importance for survival. However, insights into skeletal characteristics of marine mammals are limited, especially in the growing skeleton. Harbor seals (Phoca vitulina) are common marine mammals in the North and Baltic Seas and are suitable indicators of the condition of their ecosystem. Here, we analyzed whole-body areal bone mineral density (aBMD) by dual-energy X-ray absorptiometry (DXA) and lumbar vertebrae by high-resolution peripheral quantitative computed tomography (HR-pQCT) in neonate, juvenile, and adult harbor seals. Along skeletal growth, an increase in two-dimensional aBMD by DXA was paralleled by three-dimensional volumetric BMD by HR-pQCT, which could be attributed to an increasing trabecular thickness while trabecular number remained constant. Strong associations were observed between body dimensions (weight and length) and aBMD and trabecular microarchitecture (R² = 0.71-0.92, all p < 0.001). To validate the results of the DXA measurement (i.e., the standard method used worldwide to diagnose osteoporosis in humans), we performed linear regression analyses with the three-dimensional measurements from the HR-pQCT method, which revealed strong associations between the two imaging techniques (e.g., aBMD and Tb.Th: R² = 0.96, p < 0.0001). Taken together, our findings highlight the importance of systematic skeletal investigations in marine mammals during growth, illustrating the high accuracy of DXA in this context. Regardless of the limited sample size, the observed trabecular thickening is likely to represent a distinct pattern of vertebral bone maturation. As differences in nutritional status, among other factors, are likely to affect skeletal health, it appears essential to routinely perform skeletal assessments in marine mammals. Placing the results in the context of environmental exposures may allow effective measures to protect their populations.

Evaluation of a marine mammal status and trends contaminants indicator for European waters

Marine mammals are vulnerable to the bioaccumulation, biomagnification and lactational transfer of specific types of pollutants, such as industrial polychlorinated biphenyls (PCBs), due to their long-life spans, feeding at a high trophic level and unique fat stores that can serve as depots for these lipophilic contaminants. Currently, European countries are developing indicators for monitoring pollutants in the marine environment and assessing the state of biodiversity, requirements under both Regional Seas Conventions and European legislation. As sentinel species for marine ecosystem and human health, marine mammals can be employed to assess bioaccumulated contaminants otherwise below current analytical detection limits in water and lower trophic level marine biota. To aid the development of Regional Seas marine mammal contaminants indicators, as well as Member States obligations under descriptor 8 of the EU Marine Strategy Framework Directive, the current study aims to further develop appropriate methodological standards using data collected by the established UK marine mammal pollutant monitoring programme (1990 to 2017) to assess the trends and status of PCBs in harbour porpoises. Within this case study, temporal trends of PCB blubber concentration in juvenile harbour porpoises were analysed using multiple linear regression models and toxicity thresholds for the onset of physiological (reproductive and immunological) endpoints were applied to all sex-maturity groups. Mean PCB blubber concentrations were observed to decline in all harbour porpoise Assessment Units and OSPAR Assessment Areas in UK waters. However, a high proportion of animals were exposed to concentrations deemed to be a toxicological threat, though the relative proportion declined in most Assessment Units/Areas over the last 10 years of the assessment. Recommendations were made for improving the quality of the assessment going forward, including detailing monitoring requirements for the successful implementation of such an indicator.

An evolutionary medicine perspective on the cetacean pulmonary immune system - The first identification of SP-D and LBP in the bottlenose dolphin (Tursiops truncatus)

Evolutionary medicine expresses the present status of biomolecules affected by past evolutionary events. To clarify the whole picture of cetacean pneumonia, which is a major threat to cetaceans, their pulmonary immune system should be studied from the perspective of evolutionary medicine. In this in silico study, we focused on cetacean surfactant protein D (SP-D) and lipopolysaccharide-binding protein (LBP) as two representative molecules of the cetacean pulmonary immune system. Sequencing and analyzing SP-D and LBP in the bottlenose dolphin (Tursiops truncatus) lung and liver tissue collected post-mortem elucidated not only basic physicochemical properties but also their evolutionary background. This is the first study to report the sequences and expression of SP-D and LBP in the bottlenose dolphin. Besides, our findings also suggest the direction of an evolutionary arms race in the cetacean pulmonary immune system. These results have important positive implications for cetacean clinical medicine.

Virulence factors of Gram-negative bacteria from free-ranging Amazon river dolphins (Inia geoffrensis)

Freshwater cetaceans play a significant role as sentinel animals, providing important data on animal species and aquatic ecosystem health. They also may serve as potential reservoirs of emerging pathogens and host virulence genes in their microbiota. In this study, we evaluated virulence factors produced by Gram-negative bacteria recovered from individuals belonging to two populations of free-ranging Amazon river dolphins (Inia geoffrensis). A total of 132 isolates recovered from the oral cavity, blowhole, genital opening and rectum of 21 river dolphins, 13 from Negro River and 8 from Tapajós River, Brazil, were evaluated for the production of virulence factors, such as biofilms and exoproducts (proteases, hemolysins and siderophores), in planktonic and biofilm forms. In planktonic form, 81.1% (107/132) of the tested bacteria of free-ranging Amazon river dolphins were able to produce virulence factors, with 44/132 (33.4%), 65/132 (49,2%) and 54/132 (40,9%) positive for protease, hemolysin and siderophore production, respectively. Overall, 57/132 (43.2%) of the isolates produced biofilms and, under this form of growth, 66/132 (50%), 88/132 (66.7%) and 80/132 (60.6%) of the isolates were positive for protease, hemolysin and siderophore production. In general, the isolates showed a higher release of exoproducts in biofilm than in planktonic form (P < 0.001). The present findings show that Amazon river dolphins harbor potentially pathogenic bacteria in their microbiota, highlighting the importance of monitoring the micro-organisms from wild animals, as they may emerge as pathogens for humans and other animals.

Emerging and legacy contaminants in common minke whale from the Barents sea

Persistent organic pollutants (POPs), including brominated flame retardants (BFRs), perfluoroalkyl substances (PFAS) and metals, can accumulate in marine mammals and be transferred to offspring. In this study, we analyzed 64 lipophilic POPs, including four emerging BFRs, in the blubber, liver and muscle of 17 adult common minke whales (Balaenoptera acutorostrata) from the Barents Sea to investigate occurrence and tissue partitioning. In addition, the placental transfer concentration ratios of 14 PFAS and 17 metals were quantified in the muscle of nine female-fetus pairs to investigate placental transfer. Legacy lipophilic POPs were the dominating compound group in every tissue, and we observed generally lower levels compared to previous studies from 1992 to 2001. We detected the emerging BFRs hexabromobenzene (HBB) and pentabromotoluene (PBT), but in low levels compared to the legacy POPs. We detected nine PFAS, and levels of perfluorooctane sulfonate (PFOS) were higher than detected from the same population in 2011, whilst levels of Hg were comparable to 2011. Levels of lipophilic contaminants were higher in blubber compared to muscle and liver on both a wet weight and lipid adjusted basis, but tissue partitioning of the emerging BFRs could not be determined due to the high number of samples below the limit of detection. The highest muscle ΣPFAS levels were quantified in fetuses (23 ± 8.7 ng/g ww), followed by adult males (7.2 ± 2.0 ng/gg ww) and adult females (4.5 ± 1.1 ng/g ww), showing substantial placental transfer from mother to fetus. In contrast, Hg levels in the fetus were lower than the mother. Levels were under thresholds for risk of health effects in the whales. This study is the first to report occurrence and placental transfer of emerging contaminants in common minke whales from the Barents Sea, contributing valuable new data on pollutant levels in Arctic wildlife.

Immunity in Sea Turtles: Review of a Host-Pathogen Arms Race Millions of Years in the Running

The immune system of sea turtles is not completely understood. Sea turtles (as reptiles) bridge a unique evolutionary gap, being ectothermic vertebrates like fish and amphibians and amniotes like birds and mammals. Turtles are ectotherms; thus, their immune system is influenced by environmental conditions like temperature and season. We aim to review the turtle immune system and note what studies have investigated sea turtles and the effect of the environment on the immune response. Turtles rely heavily on the nonspecific innate response rather than the specific adaptive response. Turtles' innate immune effectors include antimicrobial peptides, complement, and nonspecific leukocytes. The antiviral defense is understudied in terms of the diversity of pathogen receptors and interferon function. Turtles also mount adaptive responses to pathogens. Lymphoid structures responsible for lymphocyte activation and maturation are either missing in reptiles or function is affected by season. Turtles are a marker of health for their marine environment, and their immune system is commonly dysregulated because of disease or contaminants. Fibropapillomatosis (FP) is a tumorous disease that afflicts sea turtles and is thought to be caused by a virus and an environmental factor. We aim, by exploring the current understanding of the immune system in turtles, to aid the investigation of environmental factors that contribute to the pathogenesis of this disease and provide options for immunotherapy.

Whiskers provide time-series of toxic and essential trace elements, Se:Hg molar ratios, and stable isotope values of an apex Antarctic predator, the leopard seal

In an era of rapid environmental change and increasing human presence, researchers need efficient tools for tracking contaminants to monitor the health of Antarctic flora and fauna. Here, we examined the utility of leopard seal whiskers as a biomonitoring tool that reconstructs time-series of significant ecological and physiological biomarkers. Leopard seals (Hydrurga leptonyx) are a sentinel species in the Western Antarctic Peninsula due to their apex predator status and top-down effects on several Antarctic species. However, there are few data on their contaminant loads. We analyzed leopard seal whiskers (n = 18 individuals, n = 981 segments) collected during 2018-2019 field seasons to acquire longitudinal profiles of non-essential (Hg, Pb, and Cd) and essential (Se, Cu, and Zn) trace elements, stable isotope (ẟ15N and ẟ13C) values and to assess Hg risk with Se:Hg molar ratios. Whiskers provided between 46 and 286 cumulative days of growth with a mean ~ 125 days per whisker (n = 18). Adult whiskers showed variability in non-essential trace elements over time that could partly be explained by changes in diet. Whisker Hg levels were insufficient (<20 ppm) to consider most seals being at "high" risk for Hg toxicity. Nevertheless, maximum Hg concentrations observed in this study were greater than that of leopard seal hair measured two decades ago. However, variation in the Se:Hg molar ratios over time suggest that Se may detoxify Hg burden in leopard seals. Overall, we provide evidence that the analysis of leopard seal whiskers allows for the reconstruction of time-series ecological and physiological data and can be valuable for opportunistically monitoring the health of the leopard seal population and their Antarctic ecosystem during climate change.

Communicating ocean and human health connections: An agenda for research and practice

The emergence of ocean and human health (OHH) science as a distinct scholarly discipline has led to increased research outputs from experts in both the natural and social sciences. Formal research on communication strategies, messaging, and campaigns related to OHH science remains limited despite its importance as part of the social processes that can make knowledge actionable. When utilized to communicate visible, local issues for targeting audiences, OHH themes hold the potential to motivate action in pursuit of solutions to environmental challenges, supplementing efforts to address large-scale, abstract, or politicized issues such as ocean acidification or climate change. Probing peer-reviewed literature from relevant areas of study, this review article outlines and reveals associations between society and the quality of coastal and marine ecosystems, as well as key themes, concepts, and findings in OHH science and environmental communication. Recommendations for future work concerning effective ocean and human health science communication are provided, creating a platform for innovative scholarship, evidence-based practice, and novel collaboration across disciplines.

Seascape genomics of common dolphins (Delphinus delphis) reveals adaptive diversity linked to regional and local oceanography

Background

High levels of standing genomic variation in wide-ranging marine species may enhance prospects for their long-term persistence. Patterns of connectivity and adaptation in such species are often thought to be influenced by spatial factors, environmental heterogeneity, and oceanographic and geomorphological features. Population-level studies that analytically integrate genome-wide data with environmental information (i.e., seascape genomics) have the potential to inform the spatial distribution of adaptive diversity in wide-ranging marine species, such as many marine mammals. We assessed genotype-environment associations (GEAs) in 214 common dolphins (Delphinus delphis) along > 3000 km of the southern coast of Australia.

Results

We identified 747 candidate adaptive SNPs out of a filtered panel of 17,327 SNPs, and five putatively locally-adapted populations with high levels of standing genomic variation were disclosed along environmentally heterogeneous coasts. Current velocity, sea surface temperature, salinity, and primary productivity were the key environmental variables associated with genomic variation. These environmental variables are in turn related to three main oceanographic phenomena that are likely affecting the dispersal of common dolphins: (1) regional oceanographic circulation, (2) localised and seasonal upwellings, and (3) seasonal on-shelf circulation in protected coastal habitats. Signals of selection at exonic gene regions suggest that adaptive divergence is related to important metabolic traits.

Conclusion

To the best of our knowledge, this represents the first seascape genomics study for common dolphins (genus Delphinus). Information from the associations between populations and their environment can assist population management in forecasting the adaptive capacity of common dolphins to climate change and other anthropogenic impacts.

Body burdens and distribution of mercury and selenium in bottlenose, striped and Risso's dolphins along the Adriatic coast: A 20-year retrospective

Top marine predators present high mercury concentrations in their tissues due to biomagnification in the marine food chain. This study reports mercury (Hg) and selenium (Se) status, and the Hg:Se molar ratio assessment in bottlenose (Tursiops truncatus), striped (Stenella coeruleoalba) and Risso's dolphins (Grampus griseus). Total Hg and Se concentrations were determined in muscle, liver, kidney, lung, spleen, adipose tissue and skin collected from 186 specimens stranded in the Croatian part of Adriatic Sea from 1995 to 2014. Total Hg concentrations in tissue samples ranged from 0.001 in the spleen to 2238 mg/kg wet weight in liver. Se concentrations in dolphin samples ranged from 0.010 to 2916 mg/kg ww. Minimum Se concentration was found in muscle and maximum Se concentration were found in liver of bottlenose dolphin. Hg and Se levels in Risso's dolphins showed higher concentrations in all tissues in comparison to bottlenose and striped dolphins. Significant and positive correlations were observed between age and Hg concentrations (P < 0.05). In 66.6 % of Risso's, 15.3 % of bottlenose dolphins and one stranded striped dolphin in this study, the hepatic concentration of Hg exceeded the higher toxic thresholds (400 mg/kg w.w.) previously defined as evidence of liver damage in marine mammals. The Hg:Se molar ratio in the liver of Risso's dolphin was 0.670. The liver of adult bottlenose dolphins showed expected values (0.870), while the liver of young dolphins had a high ratio (0.750), non-specific for the age group. The Hg:Se molar ratio in the liver of striped dolphins was 0.390, which is lower than the literature values.

Exploring lipid affinities of persistent organic pollutants and MeO-PBDEs in blubber of marine mammals

Although lipophilic compounds have been the focus of numerous studies in marine mammals, their association with lipids is widely accepted, but rarely scrutinized. This pilot study aimed to investigate potential relationships between individual lipids from different lipid classes identified through a non-targeted Nuclear Magnetic Resonance (NMR) based lipidomics approach and legacy POPs in the blubber of long-finned pilot whales, sperm whales, common bottlenose dolphins, and Indo-Pacific bottlenose dolphins. Concentrations of selected POPs such as HCB and HCHs in sperm whales from Tasmania were found to differ from those in long-finned pilot whales and common bottlenose dolphins from the same location. Profiles of NMR spectra measured in blubber of sperm whales were also distinctly different compared to the pilot whales and common bottlenose dolphins. Two groups of Indo-Pacific bottlenose dolphins from South Australia that were 20 years apart showed highly comparable profiles of NMR signals despite having higher concentrations of several POP classes in the more recent group. More specific correlations were investigated between selected POPs (n = 12) and all detected NMR signals (n = 63) in all species. Outcomes were species-specific, but difficult to interpret due to the lack of available literature for marine mammals and the small sample sizes per species. Because of the key role of lipids in the bioaccumulation of POPs and in the incidence of diseases, more attention should be given to the identification and characterization of lipid species in future toxicological studies. However, future studies should focus on one marine mammal species to increase sample sizes and limit the number of confounding factors, such as diet, that can influence POP and lipid levels and profiles.

Non-essential heavy metals and protective effects of selenium against mercury toxicity in endangered Australian sea lion (Neophoca cinerea) pups with hookworm disease

The endangered Australian sea lion, Neophoca cinerea, faces ongoing population decline. Identification of key threats to N. cinerea population recovery, including disease and pollutants, is an objective of the species' recovery plan. Previous studies have identified Uncinaria sanguinis, an intestinal nematode, as a significant cause of disease and mortality in N. cinerea pups. Given the impact of heavy metals on the immune response, investigation of these pollutants is critical. To this end, the concentrations of arsenic (As), total mercury (Hg), cadmium (Cd), chromium (Cr), lead (Pb) and selenium (Se) were determined in blood collected from N. cinerea pups sampled during the 2017/18, 2019 and 2020/21 breeding seasons at Seal Bay Conservation Park, South Australia. Significant differences (p < 0.05) in Hg, As, Cr, and Se concentrations and molar ratio of Se:Hg were seen between breeding seasons. Pup age, maternal parity and inter-individual foraging behaviour were considered factors driving these differences. The concentrations of Hg (357, 198 and 241 µg/L) and As (225, 834 and 608 µg/L) were high in 2017/18, 2019 and 2020/21 respectively with Hg concentrations in the blood of N. cinerea pups above toxicological thresholds reported for marine mammals. The concentration of Se (1332, 647, 763 µg/L) and molar ratio of Se:Hg (9.47, 7.98 and 6.82) were low compared to other pinniped pups, indicating potential vulnerability of pups to the toxic effects of Hg. Significant (p < 0.05) negative associations for Pb and Cd with several red blood cell parameters suggest they could be exacerbating the anaemia caused by hookworm disease. Temporal (age-related) changes in element concentrations were also seen, such that pup age needs to be considered when interpreting bioaccumulation patterns. Further investigation of the role of elevated heavy metal concentrations on N. cinerea pup health, disease and development is recommended, particularly with respect to immunological impacts.

Trace metal concentrations in California sea lions from rookeries exposed to different levels of coastal urbanization in Baja California, Mexico

Concentrations of total mercury, total selenium, and cadmium ([THg], [TSe], [Cd]) were determined in hair of California sea lion (Zalophus californianus) pups from four islands of the Gulf of California and the Baja California Pacific coast (NG, CG, NP, and CP) to identify geographical differences and the effect of Se against Hg toxicity (TSe:THg molar ratio). THg displayed a strong north-south trend for both ecoregions, while TSe presented a significantly high concentration only for CG. TSe:THg molar ratios decreased when [THg] increased, with the lowest ratios presenting in NG pups, in which [THg] exceeded toxicological thresholds of concern. [Cd] presented similar values at all study sites except CG, which presented the lowest level. The present study shows that proximity to urbanized coastal areas has a strong influence on [THg] in pups, while [TSe] and [Cd] are probably more related to the physiological requirements of the species, and environmental conditions.

Field measurements reveal exposure risk to microplastic ingestion by filter-feeding megafauna

Microparticles, such as microplastics and microfibers, are ubiquitous in marine food webs. Filter-feeding megafauna may be at extreme risk of exposure to microplastics, but neither the amount nor pathway of microplastic ingestion are well understood. Here, we combine depth-integrated microplastic data from the California Current Ecosystem with high-resolution foraging measurements from 191 tag deployments on blue, fin, and humpback whales to quantify plastic ingestion rates and routes of exposure. We find that baleen whales predominantly feed at depths of 50-250 m, coinciding with the highest measured microplastic concentrations in the pelagic ecosystem. Nearly all (99%) microplastic ingestion is predicted to occur via trophic transfer. We predict that fish-feeding whales are less exposed to microplastic ingestion than krill-feeding whales. Per day, a krill-obligate blue whale may ingest 10 million pieces of microplastic, while a fish-feeding humpback whale likely ingests 200,000 pieces of microplastic. For species struggling to recover from historical whaling alongside other anthropogenic pressures, our findings suggest that the cumulative impacts of multiple stressors require further attention.

Dolphins and sea turtles may host zoonotic parasites and pathogenic bacteria as indicators of anthropic pressure in the Gulf of Taranto (Northern Ionian Sea, Central-Eastern Mediterranean Sea)

The occurrence of protozoan parasites Giardia duodenalis and Cryptosporidium spp. such as the pathogenic bacteria Salmonella spp. and Escherichia coli was molecularly investigated in the following free ranging species of striped dolphins (Stenella coeruleoalba), Risso's dolphins (Grampus griseus) as well as loggerhead (Caretta caretta) and green (Chelonia mydas) sea turtles living in the Gulf of Taranto (Mediterranean Sea). Out of forty-one investigated individuals belonging to the 4 species, 13 (31.7%) were positive to one or more pathogens and zoonotic G. duodenalis assemblage A, Cryptosporidium parvum and S. enterica were identified in striped dolphins, loggerhead and green sea turtles. In this work, the presence of these opportunistic pathogens has been investigated in fecal samples of free ranging dolphin and sea turtle species for the first time. Moreover, this is the first record of C. parvum in loggerhead sea turtles. These results may provide baseline data for the potential role of cetaceans and sea turtles as potential sentinel species for zoonotic and terrestrial pathogens in the marine environment.

Implications of Escherichia coli community diversity in free-ranging Australian pinniped pups

Escherichia coli is a widely studied bacterium, commonly used as an indicator of faecal contamination. Investigations into the structure and diversity of E. coli in free-ranging wildlife species has been limited. The objective of this study was to characterise intra-individual and inter-species E. coli phylotype and B2 sub-type diversity in free-ranging Australian pinniped pups, to determine whether a single E. coli colony is representative of the phylotype and B2 sub-type diversity in these hosts. Faecal samples were collected from free-ranging Australian fur seal (Arctocephalus pusillus doriferus), Australian sea lion (Neophoca cinerea) and long-nosed fur seal (Arctocephalus forsteri) pups from three breeding colonies between 2018 and 2021. Faecal swabs from thirty randomly selected pups (n = 10 from each species) were cultured and ten E. coli colonies were selected from each culture based on morphology and separation between colonies on agar plates. Molecular screening techniques were utilised to assign isolates to phylotypes and B2 sub-types. There was no significant difference (p > 0.05) in either intra-individual or inter-species E. coli phylotype and B2 sub-type diversity. The B2 phylotype was the most dominant, with 78% of isolates (n = 234) assigned to this phylotype. Host factors (species, weight [kg] and standard length [cm]) did not significantly affect phylotype diversity. The absence of intra-individual and inter-species differences in E. coli diversity at a phylotype level suggests that a single E. coli colony could be used as an indicator of overall diversity of E. coli at a phylotype level in A. p. doriferus, N. cinerea and A. forsteri pups. These findings can be used to simplify and improve the efficiency of sampling protocols for ongoing monitoring of human-associated E. coli phylotypes in free-ranging pinniped populations.

Organotins Remain a Serious Threat to the Indo-Pacific Humpback Dolphins in the Pearl River Estuary

Marine mammals often accumulate high levels of environmental contaminants, even those that are globally regulated regarding usage, raising concerns about their health status. Here, we conducted the first investigation of tissue distribution, spatiotemporal trends, and potential risks of six organotin compounds (OTs) in Indo-Pacific humpback dolphins (n = 101) from the northern South China Sea during 2003-2021. We detected the highest level of hepatic triphenyltin in these humpback dolphins compared with the results reported in cetaceans globally, and the liver accumulated the highest OT concentrations than other analyzed tissues. Despite the downward trend of butyltins in humpback dolphins after the global ban on the use of OTs as antifouling paints, levels of phenyltins have continued to increase over the past 20 years, suggesting that the other applications of phenyltins in South China remain prevalent. In vitro and in vivo analyses revealed that tissue-relevant doses of OTs could induce agonistic effects on the dolphin peroxisome proliferator-activated receptor γ as a master regulator of lipid homeostasis and altered the dolphin fatty acid profiles. Our results highlight the lipid-disrupting effects of current OT exposure in humpback dolphins and emphasize the need for further efforts to eliminate OT contamination in South China.

Occurrence of Antimicrobial-Resistant Escherichia coli in Marine Mammals of the North and Baltic Seas: Sentinels for Human Health

Antimicrobial resistance is a global health threat that involves complex, opaque transmission processes in the environment. In particular, wildlife appears to function as a reservoir and vector for antimicrobial-resistant bacteria as well as resistance genes. In the present study, the occurrence of antimicrobial-resistant Escherichia coli was determined in marine mammals and various fish species of the North and Baltic Seas. Rectal or faecal swabs were collected from 66 live-caught or stranded marine mammals and 40 fish specimens. The antimicrobial resistance phenotypes and genotypes of isolated E. coli were determined using disk diffusion tests and PCR assays. Furthermore, isolates were assigned to the four major phylogenetic groups of E. coli. Additionally, post mortem examinations were performed on 41 of the sampled marine mammals. The investigations revealed resistant E. coli in 39.4% of the marine mammal samples, while no resistant isolates were obtained from any of the fish samples. The obtained isolates most frequently exhibited resistance against aminoglycosides, followed by β-lactams. Of the isolates, 37.2% showed multidrug resistance. Harbour porpoises (Phocoena phocoena) mainly carried E. coli isolates belonging to the phylogenetic group B1, while seal isolates were most frequently assigned to group B2. Regarding antimicrobial resistance, no significant differences were seen between the two sampling areas or different health parameters, but multidrug-resistant isolates were more frequent in harbour porpoises than in the sampled seals. The presented results provide information on the distribution of antimicrobial-resistant bacteria in the North and Baltic Seas, and highlight the role of these resident marine mammal species as sentinels from a One Health perspective.

Global PBDE contamination in cetaceans. A critical review

This review summarizes the most relevant information on PBDEs' occurrence and their impacts in cetaceans at global scale, with special attention on the species with the highest reported levels and therefore the most potentially impacted by the current and continuous release of these substances. This review also emphasizes the anthropogenic and environmental factors that could increase concentrations and associated risks for these species in the next future. High PBDE concentrations above the toxicity threshold and stationary trends have been related to continuous import of PBDE-containing products in cetaceans of Brazil and Australia, where PBDEs have never been produced. Non-decreasing levels documented in cetaceans from the Northwest Pacific Ocean might be linked to the increased e-waste import and ongoing production and use of deca-BDE that is still allowed in China. Moreover, high levels of PBDEs in some endangered species such as beluga whales (Delphinapterus leucas) in St. Lawrence Estuary and Southern Resident killer whales (Orcinus Orca) are influenced by the discharge of contaminated waters deriving from wastewater treatment plants. Climate change related processes such as enhanced long-range transport, re-emissions from secondary sources and shifts in migration habits could lead to greater exposure and accumulation of PBDEs in cetaceans, above all in those species living in the Arctic. In addition, increased rainfall could carry greater amount of contaminants to the marine environment, thereby, enhancing the exposure and accumulation especially for coastal species. Synergic effects of all these factors and ongoing emissions of PBDEs, expected to continue at least until 2050, could increase the degree of exposure and menace for cetacean populations. In this regard, it is necessary to improve current regulations on PBDEs and broader the knowledge about their toxicological effects, in order to assess health risks and support regulatory protection for cetacean species.

Trace elements in blood of Baltic gray seal pups (Halichoerus grypus) from the Gulf of Riga and their relationship with biochemical and clinical parameters

Trace elements are pollutants of both natural and anthropogenic origin which can influence negatively on ecosystem and wildlife health. We evaluated trace element in blood samples of gray seal (Halichoerus grypus) stranded in the Gulf of Riga and their influence on their health status through hematological and biochemical profiles. Zn showed the highest levels followed by Cu > Se > Pb > THg > As. Cr and Cd were not detected. Most trace element levels were generally comparable to those reported in seal species; however, high Pb values were observed in those sample showing detectable concentrations (<0.046-257.6 μg/kg ww). Significant positive correlations were found between trace elements concentrations and various biochemical parameters, including Se-ASAT, Se:Hg-ASAT, Cu-TP, Cu-ALB, CuCa, Zn-ALAT, ZN-LDH, ZnP, Zn-Segment neutrophils, and Pb-CK. Nevertheless, most relationships were not strong enough (p > 0.04) to assume a toxicological implication. Despite its limitations, this information could serve as the baseline for future research.

Pooled resequencing of larvae and adults reveals genomic variations associated with Ostreid herpesvirus 1 resistance in the Pacific oyster Crassostrea gigas

The Ostreid herpesvirus 1 (OsHV-1) is a lethal pathogen of the Pacific oyster (Crassostrea gigas), an important aquaculture species. To understand the genetic architecture of the defense against the pathogen, we studied genomic variations associated with herpesvirus-caused mortalities by pooled whole-genome resequencing of before and after-mortality larval samples as well as dead and surviving adults from a viral challenge. Analysis of the resequencing data identified 5,271 SNPs and 1,883 genomic regions covering 3,111 genes in larvae, and 18,692 SNPs and 28,314 regions covering 4,863 genes in adults that were significantly associated with herpesvirus-caused mortalities. Only 1,653 of the implicated genes were shared by larvae and adults, suggesting that the antiviral response or resistance in larvae and adults involves different sets of genes or differentiated members of expanded gene families. Combined analyses with previous transcriptomic data from challenge experiments revealed that transcription of many mortality-associated genes was also significantly upregulated by herpesvirus infection confirming their importance in antiviral response. Key immune response genes especially those encoding antiviral receptors such as TLRs and RLRs displayed strong association between variation in regulatory region and herpesvirus-caused mortality, suggesting they may confer resistance through transcriptional modulation. These results point to previously undescribed genetic mechanisms for disease resistance at different developmental stages and provide candidate polymorphisms and genes that are valuable for understanding antiviral immune responses and breeding for herpesvirus resistance.

Long-term increase in mortality of Indo-Pacific humpback dolphins (Sousa chinensis) in the Pearl River Estuary following anthropic activities: Evidence from the stranded dolphin mortality analysis from 2003 to 2017

With the dramatic increase in anthropogenic threats to the Pearl River Estuary (PRE), the population size of the Indo-Pacific humpback dolphins (Sousa chinensis) has significantly decreased over the past decade. To understand the impact and potential risks of intense human activities on these dolphins, factors related to the mortality of humpback dolphins in the PRE were investigated by a detailed examination of 343 dolphin specimens stranded during 2003-2017. There was a significant (p < 0.01) increasing trend for humpback dolphin stranding, reflecting the accelerating rate of the population decline. A large proportion of strandings (35.88%) were neonates. A low recruitment rate implies slow population growth, and hence, limited capacity to resist anthropogenic stress. The most commonly diagnosed causes of death were vessel collision and net entanglement. The concentrations of trace metals, polychlorinated biphenyl (PCB) congeners, dichlorodiphenyltrichloroethane, polycyclic aromatic hydrocarbons, and most of per- and polyfluoroalkyl substances (PFASs) in the dolphin samples were greater than those previously reported in cetaceans globally. Furthermore, Cu, PCB77, PCB169, PCB81, PCB37, and PFASs (excluding PFBA, PFPeA, PFHxA, PFHxDA, and PFODA) were the major pollutants accumulated in neonates. 67% of PCB, 78% of Cu, and 100% of perfluorooctane sulfonate concentrations in the neonates exceeded the threshold for toxicological effects in marine mammals, suggesting that these compounds could be important factors contributing to the low survival rate of calves in this area. This study revealed that vessel transportation, fishing activities, and pollutant bioaccumulation are the three major causes of humpback dolphin mortality in the PRE. These results highlight the need for more efforts to restrict anthropogenic activities, especially vessel traffic, the catching of these marine animals and fishing, and pollutant discharge, in order to prevent vulnerable species from continuous population decline and further extinction.

Franciscana dolphins, Pontoporia blainvillei, as environmental sentinels of the world's largest mining disaster: Temporal trends for organohalogen compounds and their consequences for an endangered population

On November 5th, 2015, the Fundão dam collapsed in Minas Gerais, southeastern Brazil, releasing millions of cubic meters of mud containing mining residue into the Doce River. Two weeks later, the mud arrived to the marine environment, triggering changes in franciscana dolphin habitat, Pontoporia blainvillei, from Franciscana Management Area Ia. This is an isolated population of the most endangered cetacean species in the South Atlantic Ocean. Organohalogen compounds (OHCs) may pose a threat to this endangered population because of their endocrine disrupting properties. Hence, this study sought to determine if there were differences in the bioaccumulation profile of OHC (PCBs, DDTs, Mirex, HCB, HCHs, PBDEs, PBEB, HBBZ and MeO-BDEs) in franciscana dolphins before and after dam collapse and to build a temporal trend. Blubber of 33 stranded individuals was collected in Espírito Santo state for organohalogen assessment between 2003 and 2019. Differences were found between franciscana dolphins collected prior to and after the disaster. Additionally, significant temporal trends for organochlorine pesticides and natural and anthropogenic organobromine were detected. The increase in pesticide concentrations after 2015 is suggestive of their reavailability in the environment. The decline in organobromine over time could be due to their debromination in the marine environment and alterations in the composition of their natural producers. PCBs remained stable during the period of the study. Our findings show an increase in endocrine disruptor concentrations, which is of great concern for this endangered population.

Survey of selected pathogens in free-ranging pinnipeds in Uruguay

Marine mammals, regarded as sentinels of aquatic ecosystem health, are exposed to different pathogens and parasites under natural conditions. We surveyed live South American fur seals Arctocephalus australis and South American sea lions Otaria flavescens in Uruguay for Leptospira spp., canine distemper virus (CDV), Mycobacterium spp., Toxoplasma gondii, and Neospora caninum. Samples were collected from 2007 to 2013. The seroprevalence of Leptospira spp. was 37.6% positive, 50.9% negative, and 11.5% suspect for A. australis (n = 61) while for O. flavescens (n = 12) it was 67% positive, 25% negative, and 8% suspect. CDV RNA was not detected in any of the analyzed samples. Most animals tested seropositive to tuberculosis antigens by WiZo ELISA (A. australis: 29/30; O. flavescens: 20/20); reactivity varied with a novel ELISA test (antigens MPB70, MPB83, ESAT6 and MPB59). Seroprevalence against N. caninum and T. gondii was 6.7 and 13.3% positive for O. flavescens and 0 and 2.2% positive for A. australis respectively. To evaluate possible sources of infection for pinnipeds, wild rats Rattus rattus and semi-feral cats Felis catus were also tested for Leptospira spp. and T. gondii respectively. Water samples tested for Leptospira revealed saprofitic L. bioflexa. Pathogenic Leptospira were detected in the kidneys of 2 rats, and cats tested positive for T. gondii (100%). These results represent a substantial contribution to the study of the health status of wild pinnipeds in Uruguay.

A Comparative Study of Mini-FLOTAC With Traditional Coprological Techniques in the Analysis of Cetacean Fecal Samples

Free-ranging cetaceans are considered sentinels for the marine ecosystem's health. New and non-invasive methods have been set up for the collection of fecal samples from free-ranging big whales at sea, permitting to gain an excellent epidemiological picture of parasitic infections in wild populations. To select the best protocol to be used for copromicroscopic examination in cetaceans stool samples, we evaluated the sensitivity of two commonly used techniques, i.e., a sedimentation-floatation method and the Mini-FLOTAC through validation by helminth isolation from the digestive tract. For this aim, gastrointestinal content and fecal samples were collected during necropsy from 44 cetaceans, including bottlenose dolphins (Tursiops truncatus), striped dolphins (Stenella coeruleoalba), sperm whales (Physeter macrocephalus), Risso's dolphins (Grampus griseus), Cuvier's beaked whales (Ziphius cavirostris), pilot whale (Globicephala melas), and fin whales (Balaenoptera physalus). Helminths were recovered through washing and filtering of the gastrointestinal contents and morphologically identified. Copromicroscopic examinations were performed on formalin-preserved fecal samples, using a sodium nitrate, sodium thiosulphate, and sucrose solution (s.g. = 1.450) for both methods. Helminths belonging to 9 taxa (i.e., the trematodes Synthesium tursionis, Synthesium delamurei, Campula palliata, Braunina cordiformis, Pholeter gastrophilus, the nematode Anisakis sp., cestodes of the family Tetrabothriidae and the acanthocephalan Bolbosoma sp.) were isolated. Eggs referable to the same taxa, with the exception of cestodes, were found in copromicroscopic analyses. Sensitivity of the Mini-FLOTAC method appeared higher or equal for all taxa, proving superior to the sedimentation-flotation method for the detection of all except Anisakis sp. The concordance of the two tests indeed revealed a moderate to perfect agreement (kappa values 0.42–1). Not excluding the limitations inherent to the techniques themselves, explanations for false-negative results at copromicroscopy could be linked to parasite-related factors, including prepatent infections, low parasitic burdens, or intermittent egg shedding. Notwithstanding these limitations, this study evidenced that the Mini-FLOTAC protocol approximates more accurately the composition of the gastrointestinal helminthic community of cetaceans from copromicroscopic examination, providing at the same time a quantitative estimation.

Assessing Marine Endocrine-Disrupting Chemicals in the Critically Endangered California Condor: Implications for Reintroduction to Coastal Environments

Coastal reintroduction sites for California condors (Gymnogyps californianus) can lead to elevated halogenated organic compound (HOC) exposure and potential health impacts due to the consumption of scavenged marine mammals. Using nontargeted analysis based on comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC/TOF-MS), we compared HOC profiles of plasma from inland and coastal scavenging California condors from the state of California (CA), and marine mammal blubber from CA and the Gulf of California off Baja California (BC), Mexico. We detected more HOCs in coastal condors (32 ± 5, mean number of HOCs ± SD, n = 7) than in inland condors (8 ± 1, n = 10) and in CA marine mammals (136 ± 87, n = 25) than in BC marine mammals (55 ± 46, n = 8). ∑DDT-related compounds, ∑PCBs, and total tris(chlorophenyl)methane (∑TCPM) were, respectively, ∼7, ∼3.5, and ∼148 times more abundant in CA than in BC marine mammals. The endocrine-disrupting potential of selected polychlorinated biphenyls (PCB) congeners, TCPM, and TCPMOH was determined by in vitro California condor estrogen receptor (ER) activation. The higher levels of HOCs in coastal condors compared to those in inland condors and lower levels of HOC contamination in Baja California marine mammals compared to those from the state of California are factors to consider in condor reintroduction efforts.

Toxoplasma gondii Infection in Marine Animal Species, as a Potential Source of Food Contamination: A Systematic Review and Meta-Analysis

PURPOSE

Many marine animals are infected and susceptible to toxoplasmosis, which is considered as a potential transmission source of Toxoplasma gondii to other hosts, especially humans. The current systematic review and meta-analysis aimed to determine the prevalence of T. gondii infection among sea animal species worldwide and highlight the existing gaps.

METHODS

Data collection was systematically done through searching databases, including PubMed, Science Direct, Google Scholar, Scopus, and Web of Science from 1997 to July 2020.

RESULTS

Our search strategy resulted in the retrieval of 55 eligible studies reporting the prevalence of marine T. gondii infection. The highest prevalence belonged to mustelids (sea otter) with 54.8% (95% CI 34.21-74.57) and cetaceans (whale, dolphin, and porpoise) with 30.92% (95% CI 17.85-45.76). The microscopic agglutination test (MAT) with 41 records and indirect immunofluorescence assay (IFA) with 30 records were the most applied diagnostic techniques for T. gondii detection in marine species.

CONCLUSIONS

Our results indicated the geographic distribution and spectrum of infected marine species with T. gondii in different parts of the world. The spread of T. gondii among marine animals can affect the health of humans and other animals; in addition, it is possible that marine mammals act as sentinels of environmental contamination, especially the parasites by consuming water or prey species.

Untargeted plasma metabolomic analysis of wild bottlenose dolphins (Tursiops truncatus) indicate protein degradation when in poorer health

Cumulative exposure to sub-lethal anthropogenic stressors can affect the health and reproduction of coastal cetaceans and hence their population viability. To date, we do not have a clear understanding of the notion of health for cetaceans in an ecological context; that is, how health status affects the ability of individuals to survive and reproduce. Here, we make use of a unique health-monitoring programme of estuarine bottlenose dolphins in South Carolina and Florida to determine de novo changes in biological pathways, using untargeted plasma metabolomics, depending on the health status of individuals obtained from veterinary screening. We found that individuals that were in a poor health state had lower circulating amino acids pointing towards increased involvement of gluconeogenesis (i.e., new formation of glucose). More mechanistic work is needed to disentangle the interconnection between health and energy metabolism in cetaceans to mediate potential metabolic constraints they may face during periods of stress.

A comparative study of the fecal microbiota of gray seal pups and yearlings ‐ a marine mammal sentinel species

Gray seals (Halichoerus grypus) can act as sentinel species reflecting the condition of the environment they inhabit. Our previous research identified strains of pathogenic Campylobacter and Salmonella, originating from both human and agricultural animal hosts, on rectal swabs from live gray seal (H. grypus) pups and yearlings on the Isle of May, Scotland, UK. We examined rectal swabs from the same pup (n = 90) and yearling (n = 19) gray seals to gain further understanding into the effects of age‐related changes (pup vs. yearling) and three different natal terrestrial habitats on seal pup fecal microbiota. DNA was extracted from a subset of rectal swabs (pups n = 23, yearlings n = 9) using an optimized procedure, and the V4 region of the 16S ribosomal RNA gene was sequenced to identify each individual's microbiota. Diversity in pup samples was lower (3.92 ± 0.19) than yearlings (4.66 ± 0.39) although not significant at the p = 0.05 level (p = 0.062) but differences in the composition of the microbiota were (p < 0.001). Similarly, differences between the composition of the microbiota from pups from three different terrestrial habitats (Pilgrim's Haven [PH], Rona Rocks [RR], and Tarbet Slope [TS]) were highly significant (p < 0.001). Pairwise tests showed significant differences between all three habitats: PH versus TS (p = 0.019), PH versus RR (p = 0.042) and TS versus RR (p = 0.020). This preliminary study suggests a general trend, that seal microbiomes are modified by both age and, in pups, different terrestrial habitats. Furthermore, knowledge of the microbiota species present has the potential to be used in determining the environmental quality index.

Seasonal and diel influences on bottlenose dolphin acoustic detection determined by whistles in a coastal lagoon in the southwestern Gulf of California

Marine mammals in subtropical coastal habitats are sentinels of the health of the ecosystem and offer important ecosystem services. They rely on prey that pursues feeding opportunities, while both avoid unfavorable conditions. In many cases, these predator-prey dynamics fluctuate seasonally and are regulated by lunar, tidal, and/or diel cycles (hour). However, these rhythmical patterns may vary under different seasonal conditions. Bottlenose dolphins (Tursiops truncatus) in the Ensenada de La Paz in Baja California Sur, Mexico, were detected acoustically over the course of an annual cycle on 21 separate occasions, covering 640 h from June 2017 to May 2019. The presence of bottlenose dolphins was examined using Generalized Additive Models (GAM) including variables that are related directly to their habitat (direct variables: hour, distance, depth) and to their prey (indirect variables: SST, moon phase and tides). Seasonal differences in the presence of bottlenose dolphins were influenced more by indirect variables (explained deviance: 34.8% vs. 37.7%). Hourly acoustic detections occurred less frequently when SST exceeded 27.4 °C (Aug-End of Nov.) and more frequently at moderate temperatures (22.7 °C to 26.3 °C) in May through July. Moreover, bottlenose dolphins were detected more frequently during waning and new moon phases, at the onset of flood and ebb tides, and during day (04:00 to 20:00). The seasonal differences in acoustic detections rates were highlighted by the global GAM and hierarchical clustering. The strong seasonal pattern indicated possible interactions with rhythmic pattern of bottlenose dolphins. Four candidate variables (SST, moon, tide, and hour) were tested for plausible interaction terms additional to their individual consideration, out of which only hour changed significantly between seasons. The patterns of presence likely increase feeding opportunities or may favor other behaviors such as socializing, resting, or nursing. These might prove responsible for the distinct occurrence and hourly patterns of bottlenose dolphins.

Fetal mercury concentrations in central California Pacific harbor seals: Associated drivers and outcomes

Mercury (Hg) is a well-known toxicant in wildlife and humans. High total Hg concentrations ([THg]) have been reported in central California harbor seals Phoca vitulina richardii. We evaluated the effects of presence/absence of early natal coat (lanugo), year (2012 to 2017), sex, stranding location, and trophic ecology (ẟ¹³C and ẟ¹⁵N values) on hair [THg] along coastal central California. Also examined were [THg] effects on growth rates of pups in rehabilitation and probability of release (e.g., successful rehabilitation). The [THg] ranged from 0.46-81.98 mg kg^-1 dw, and ẟ¹⁵N and ẟ¹³C ranged from 13.6-21.5‰, and -17.2 to -13.0‰, respectively. Stranding location, year, and presence of lanugo coat were important factors explaining variation in [THg]. Seals from Sonoma and San Mateo County had higher [THg] than other locations. Seals with full or partial lanugo coat had lower [THg]. Seals from 2016 and 2017 had higher [THg] than those from 2015. Hair [THg] exceeded lower and upper toxicological thresholds (>20 mg kg^-1 by year (5.88% to 23.53%); >30 mg kg^-1 (0% to 12.31%)) with a pronounced increase from 2015 to 2016. Pups in 2017 had significantly higher odds ratio of [THg] above 20 mg kg^-1 than pups of 2015, and pups in 2016 had significantly higher odds ratio than those from 2013 and 2015 (similar when using 30 mg kg^-1). Pups in Sonoma County had the highest odds ratio for [THg] in lanugo above 20 mg kg^-1. ẟ¹⁵N values were higher in 2015-2017, particularly relative to 2014, probably associated with the El Niño event. The [THg] was not a good predictor for probability of release and mass-specific growth rates in captivity. Further investigation of temporal trends of [THg] in harbor seals is warranted given the relatively high percentage of samples exceeding threshold values, particularly in the most recent sampling years.

Characterization of novel papillomavirus from free-ranging Antillean manatee Trichechus manatus manatus with genital papillomatosis

The Antillean manatee Trichechus manatus manatus is an Endangered species living along the Atlantic coasts of the Americas from Florida (USA), throughout the Caribbean, to Brazil. In July 2020, a manatee with multiple wounds due to boat-inflicted trauma was rescued from the coast east of Cayo Mata, Salinas, Puerto Rico. This manatee had neutropenia, leukopenia, and monocytosis associated with immunosuppression and nutritional deficiency anemia, as well as bacteria and fungi within the lesions. The manatee had genital lesions which included papules and linear plaques, microscopically characterized by mucosal hyperplasia with cytopathic changes typical of papillomavirus infection. Superficial epithelial cells had strong nuclear immunolabeling when examined using a monoclonal antibody specific to papillomavirus. The sequencing data of PCR products with papillomavirus-specific degenerative primers indicated that these lesions contained a novel manatee papillomavirus (Trichechus manatus papillomavirus, TmPV). The genomic DNA was amplified using a rolling circle amplification, and fully sequenced to be 7586 bp (GenBank accession no. OK073977). Other TmPVs were previously isolated from Florida manatees T. manatus latirostris. This novel virus was designated TmPV type 5 (TmPV5) based on its genomic characterization and sequence comparison. The TmPV5 genome shared 50.7, 48.9, 69.4, and 62.1% similarities with TmPV1, TmPV2, TmPV3, and TmPV4, respectively. TmPV5 is classified in the genus Rhopapillomavirus together with other manatee papillomaviruses. After 2.5 mo of veterinary treatment and rehabilitation, the manatee recovered and was released. This is the first report of papillomatosis in a free-ranging Antillean manatee.

Two cetacean species reveal different long-term trends for toxic trace elements in European Atlantic French waters

Cetaceans have been naturally exposed to toxic trace elements (TEs) on an evolutionary time scale. Hence, they have developed mechanisms to control and/or mitigate their toxic effects. These long-lived species located at high trophic positions and bioaccumulating toxic elements are assumed to be good biomonitoring organisms. However, anthropogenic emissions have strongly increased environmental levels of toxic TEs in the last decades, questioning the efficiency of the detoxication mechanisms in cetaceans. In this context, temporal trends of mercury (Hg), cadmium (Cd) and lead (Pb) concentrations were studied through the analysis of 264 individuals from two cetacean species the common dolphin (Delphinus delphis) and the harbour porpoise (Phocoena phocoena) and belonging to two different Management Units (MUs) for the latter. These individuals stranded along the French Atlantic coasts from 2000s to 2017. All the trends presented were age- and sex-corrected and stable isotope ratios of carbon (δ¹³C) and nitrogen (δ¹⁵N) were measured as proxies of their feeding ecology. Results showed that Pb concentrations clearly decreased over time in both species and MUs. This decrease agrees with the lead petrol regulation after 2000s, supporting the use of these species as valuable bioindicators of changes for TE levels in the marine environment. A significant long-term increase of total Hg concentrations was only observed in common dolphins. Cadmium concentrations also revealed different trends over the period in both species. The different Hg and Cd trends observed in the two species, probably reflected a contrasted contamination of habitat and prey species than a global increase of the contamination in the environment. These results highlight the necessity and gain of using different species to monitor changes in marine environments, each of them informing on the contamination of its own ecological niche. Lastly, the Se:Hg molar ratios of species suggested a low risk for Hg toxicity over time.

Female Health Across the Tree of Life: Insights at the Intersection of Women's Health, One Health and Planetary Health

Across the tree of life, female animals share biological characteristics that place them at risk for similar diseases and disorders. Greater awareness of these shared vulnerabilities can accelerate insight and innovation in women's health. We present a broadly comparative approach to female health that can inform issues ranging from mammary, ovarian, and endometrial cancer to preeclampsia, osteoporosis, and infertility. Our focus on female health highlights the interdependence of human, animal, and environmental health. As the boundaries between human and animal environments become blurred, female animals across species are exposed to increasingly similar environmental hazards. As such, the health of female animals has unprecedented relevance to the field of woman's health. Expanding surveillance of animal populations beyond zoonoses to include noncommunicable diseases can strengthen women's health prevention efforts as environmental factors are increasingly implicated in human mortality. The physiology of nonhuman females can also spark innovation in women's health. There is growing interest in those species of which the females appear to have a level of resistance to pathologies that claim millions of human lives every year. These physiologic adaptations highlight the importance of biodiversity to human health. Insights at the intersection of women's health and planetary health can be a rich source of innovations benefitting the health of all animals across the tree of life.