Arctocephalus Tropicalis Research Articles

Post-mortem detection of hemoplasmas (hemotropic Mycoplasma spp.) in South American fur seal (Arctocephalus australis) sampled in Rio Grande do Sul State, southern Brazil

Hemotropic mycoplasmas are bacteria that attaches to erythrocytes surface, which some species presents zoonotic concerns. In the suborder Pinnipedia, genera Otaria and Arctocephalus are prominent in Brazil. This study investigated the occurrence of hemoplasmas in Arctocephalus sp. and Otaria flavescens found dead along the coast of a Southern Brazilian State. DNA from 135 spleen samples were extracted and subjected to conventional PCR protocols, targeting the 16 S rRNA and 23 S rRNA gene. Three (2.22 %) Arctocephalus australis were positive in the 16 S rRNA gene, and no samples amplified in the 23 S rRNA gene. Samples from this study clustered with Zalophus californianus and Arctocephalus tropicalis mycoplasmas on a Bayesian phylogenetic analysis. Genetic diversity analysis suggested distinct genotypes, indicating A. australis as a new host for hemoplasma, and also a potential putative novel hemoplasma genotype. These findings raises future awareness for pinnipeds conservation, and adds Mycoplasma spp. to be taken into consideration when clinically evaluating rescued animals.

Metabolomics approach for predicting stomach and colon contents in dead Arctocephalus pusillus pusillus, Arctocephalus tropicalis, Lobodon carcinophaga and Ommatophoca rossii from sub-Antarctic region.

The dietary habits of seals play a pivotal role in shaping management and administration policies, especially in regions with potential interactions with fisheries. Previous studies have utilized various methods, including traditional approaches, to predict seal diets by retrieving indigestible prey parts, such as calcified structures, from intestines, feces, and stomach contents. Additionally, methods evaluating nitrogen and stable isotopes of carbon have been employed. The metabolomics approach, capable of quantifying small-scale molecules in biofluids, holds promise for specifying dietary exposures and estimating disease risk. This study aimed to assess the diet composition of five seal species-Arctocephalus pusillus pusillus, Lobodon carcinophaga, Ommatophoca rossii, and Arctocephalus tropicalis 1 and 2-by analyzing stomach and colon contents collected from stranded dead seals at various locations. Metabolite concentrations in the seal stomach and colon contents were determined using Nuclear Magnetic Resonance Spectroscopy. Among the colon and stomach contents, 29 known and 8 unknown metabolites were identified. Four metabolites (alanine, fumarate, lactate, and proline) from stomach contents and one metabolite (alanine) from colon contents showed no significant differences between seal species (p>0.05). This suggests that traces of these metabolites in the stomach and colon contents may be produced by the seals' gut microbiome or derived from other animals, possibly indicating reliance on fish caught at sea. Despite this insight, the cause of death for stranded seals remains unclear. The study highlights the need for specific and reliable biomarkers to precisely indicate dietary exposures across seal populations. Additionally, there is a call for the development of relevant metabolite and disease interaction networks to explore disease-related metabolites in seals. Ultimately, the metabolomic method employed in this study reveals potential metabolites in the stomach and colon contents of these seal species.

Contest competition and injury in adult male sub-Antarctic fur seals

AbstractWe recorded intra-sexual behaviour of adult male sub-Antarctic fur seals Arctocephalus tropicalis at Gough Island, Southern Ocean, during the 1975/76 summer breeding season. Our re-analysed data address male ‘contest competition’, which relates to the costs of intra-sexual disputes, including fights. We considered the risks/benefits of fighting through investigation of injuries (n = 353) sustained by adult males (n = 124) in fights. Injuries were predominantly on the forequarters, especially around the insertion areas of the front flippers (41%) with its sparse pelage, compared to the neck and chest areas combined (29%), an area which is well protected by thick pelage. The infliction of serious, sometimes debilitating, injuries to competitors increases a male’s access to females. Injuries predominate in injured, defeated males that gather at non-breeding sites, suggesting that injuries inflicted by dominant males were successful in excluding competing males from breeding sites.

Incidental pinnipeds at high latitudes of the Vestfold Hills, Prydz Bay, East Antarctica

AbstractSpecies distributions are predicted to change with future climate-associated ecosystem changes such that so-called ‘vagrant’ individuals may become established or re-establish in areas currently thought to be beyond their principle ranges. Survey data were collated for occurrences of pinniped (seal) species at very high latitudes of the Vestfold Hills, East Antarctica. Aside from Weddell seals (Leptonychotes weddellii) and southern elephant seals (Mirounga leonina), which aggregate annually at the Vestfold Hills to breed and/or moult, three other pinniped species were observed with the recession of the fast-ice edge. Leopard seal (Hydrurga leptonyx) occurrences increased with an increase in a seasonally abundant prey resource, and crabeater seals (Lobodon carcinophaga) were seen at a time that coincides with their moult period. Occurrences of sub-adult male Antarctic fur seals (Arctocephalus gazella) increase the known southward range for this species and may reflect population increases at source populations in the Kerguelen Plateau area. Although there were no direct sightings of Ross seals (Ommatophoca rossii), their presence close to the Vestfold Hills was detected by underwater passive acoustic monitoring. Sightings of obligate drift-ice species and sub-Antarctic fur seals may change at the Vestfold Hills with climate-mediated changes in sea-ice conditions.

First record of ocular albinism in sub-Antarctic fur seal (Arctocephalus tropicalis) pups on Marion Island

We report on an occurrence of ocular albinism in sub-Antarctic fur seal (Arctocephalus tropicalis) pups born on Marion Island, Prince Edward Archipelago. While previous observations have documented pups with atypical lanugo pelage colorations, this is the first case involving hypopigmentation of both fur and other tissues, including the eyes and nails. During the austral summer of 2021/22, we encountered four sub-Antarctic fur seal pups displaying this anomalous pigmentation. These anomalous individuals were found along two beaches on the island’s western side and one beach on the eastern side during an island-wide fur seal census. Although the characteristics observed strongly suggest ocular albinism, confirmation would be necessary through genetic analyses. The absence of melanin in mammalian eyes is known to compromise visual acuity, which may likely result in reduced survival beyond the weaning period, explaining the paucity of such adults in this well-observed population.

Long-term changes in petrel populations on Inaccessible Island, Tristan da Cunha, inferred from the diet of Brown Skuas Stercorarius antarcticus

Petrels that breed in burrows and return to their colonies after dark are among the most poorly studied seabirds. Brown Skuas Stercorarius antarcticus (family Stercorariidae) are major predators of burrowing petrels at many seabird breeding islands in the Southern Ocean, so monitoring the diet of skuas can provide insights into petrel population trends. Regurgitated pellets and other prey remains indicate that petrels comprise 94% (monthly range 91–97%) of all prey items in the pellets and other prey remains on Inaccessible Island, Tristan da Cunha. Other seabirds (0.7%), land birds (1.0%), subantarctic fur seals Arctocephalus tropicalis (0.5%) and marine animals (3.5%) make up the remainder of the Brown Skua diet. At least 12 species of petrels are eaten, including two species that are not known to breed on Inaccessible Island, but five taxa comprised over 98% of all petrels eaten: Fregetta storm petrels (44%), White-faced Storm Petrels Pelagodroma marina (23%), Broad-billed Prions Pachyptila vittata (21%), Great Shearwaters Ardenna gravis (6%) and Common Diving Petrels Pelecanoides urinatrix (5%). Pellets containing 2 or 3 avian prey items (15% of pellets) were more likely to contain conspecifics than heterospecifics, indicating either local differences in prey distribution or individual dietary specialisation. The prey composition changed seasonally linked to the phenology of the prey species, with White-faced Storm Petrels more common in the skua diet in spring, and Fregetta storm petrels in summer. Fur seals and Great Shearwaters have become more important in the skua diet, reflecting known or suspected increases in the populations of these species on the island, whereas the populations of Common Diving Petrels and Subantarctic Shearwaters Puffinus elegans may have decreased. Modal tarsal length of Fregetta storm petrels changed from 37 mm in 1987/89 to 39 mm in 2009, suggesting a possible increase of F. tropica relative to F. grallaria in the skua diet. However, overall there has been little change in the diet of Brown Skuas on this island over the last four decades.

Patterns of occurrence of the sub-Antarctic fur seal Arctocephalus tropicalis (Gray 1872) in Southern Brazil: climatic and environmental associations

Patterns of occurrence of the sub-Antarctic fur seal Arctocephalus tropicalis (Gray 1872) in Southern Brazil: climatic and environmental associations

Cryptorchidism in the sub-Antarctic fur seal Arctocephalus tropicalis

The prevalence of cryptorchidism, a condition when one or more testes failed to move to their proper position(s), was evaluated for sub-Antarctic fur seals from Gough Island, South Atlantic. The reproductive tracts of male fur seals (n = 123) were examined and reproductive organs measured in a previous study. Only one fur seal, a 5-year-old sexually mature male, had one inguinal testis on the right side, and a small abdominal one situated below the kidney on the same side. A matching contralateral testis could not be located, neither in the scrotum or inguinal canal nor within the abdominal cavity. Amongst pinnipeds, cryptorchids rarely occurred in northern fur seals (0.01% to 0.02% prevalence), harbour seals (undetermined prevalence) and in sub-Antarctic fur seals (0.8% prevalence). Inconsequential on a population level, the rare instances of cryptorchidism in seals are interesting curiosities.

Aspects of the skin morphology in the sub-Antarctic fur seal Arctocephalus tropicalis

The present study examined whether sweat glands are present in the skin of sub-Antarctic fur seals, Arctocephalus tropicalis, using standard histological procedures and light microscopy. Aspects of the microanatomy and histology of skin were described to elucidate structure and function. Sweat glands were present both in the furred areas of the body trunk, as well as in naked skin areas of the flippers. The density of the apocrine sweat glands appeared higher in fur-covered areas than in naked areas, while the size of sweat glands was similar amongst naked and fur-covered skin. The superficial position of sweat glands in the dermis of naked skin areas and the large, coiled, tubular nature of the secretory portion seem to indicate sweat gland activity in contrast to the deep lying, narrow sweat glands in fur-covered areas.

Pinnipeds carriers of pathogenic Leptospira: New data based on molecular characterization

Leptospirosis is a bacterial disease caused by the infection of pathogenic strains of the genus Leptospira, endemic in tropical and subtropical regions. Although well documented in terrestrial animals and humans, little information is available on its distribution and impact on marine animals. Despite clinical manifestations that may occur, the occurrence of carriers was suggested in some species. Nevertheless, there are few studies regarding the infection by Leptospira sp. in marine mammals. In this context, and considering the One Health approach, the present aimed to investigate pinnipeds' role as Leptospira sp. carriers. Kidneys of 47 pinnipeds of two species, Arctocephalus australis (n = 40) and Arctocephalus tropicalis (n = 7) were collected. DNA was extracted and the diagnosis was performed through LipL32-PCR and genetic characterization based on secY gene sequencing. Phylogenetic analysis and haplotype networks were constructed. Pathogenic Leptospira sp. DNA was detected in 31.9% (15/47) of the tested pinnipeds. It was possible to amplify and sequence eight strains (6 for A. australis, 2 for A. tropicalis), all identified as L. interrogans, with high similarity with sequences from Icterohaemorrhagiae serogroup. Phylogenetic analysis revealed sequences from the present study grouped in species-specific unique clusters, but very close to others from humans, wild animals, and domestic animals. We demonstrate that pinnipeds could act as carriers, and play an important role in leptospirosis dynamics.

CLINICO-PATHOLOGIC FINDINGS AND PATHOGEN SCREENING IN FUR SEALS (ARCTOCEPHALUS AUSTRALIS AND ARCTOCEPHALUS TROPICALIS) STRANDED IN SOUTHEASTERN BRAZIL, 2018.

Among pinnipeds, four Otariidae species (eared seals) have been reported as occasional or frequent vagrants along the coast of Brazil, mainly in the southern region. These animals usually arrive debilitated during winter and are directed to rehabilitation. Nevertheless, available information on sanitary aspects of stranded pinnipeds in Brazil is limited. Increased fur seal strandings (n=23) were recorded during the 2018 winter season in southeast Brazil (Iguape, Ilha Comprida, and Ilha do Cardoso, Sao Paulo State) compared to 2017 (n=2). Of these 23 fur seals, two were found dead and were in a good postmortem condition, and four died during rehabilitation and were subsequently necropsied. The remaining fur seals were not analyzed due to advanced decomposition (9/23) or successful rehabilitation (8/23). Herein, we report the antemortem hematology (n=4) and postmortem pathologic, parasitologic, and molecular analysis results as well as the most likely cause of stranding and/ or death (CSD) in five free-ranging juvenile South American fur seals (Arctocephalus australis) and one free-ranging juvenile subantarctic fur seal (Arctocephalus tropicalis). All animals were males, and all but one had poor body condition. Pathologic examinations revealed a variety of lesions, predominantly hemodynamic disturbances, endoparasitism, and inflammatory disease processes of suspected infectious nature. Molecular analyses detected gammaherpesvirus infections in two South American seals and one subantarctic fur seal, Sarcocystis sp. in one subantarctic fur seal, and Neospora spp. in two South American fur seals. All seals were PCR-negative for morbillivirus, flavivirus, and Toxoplasma gondii. The most likely CSDs were: starvation (2), aspiration pneumonia (1), asphyxia (1), predator attack (1), and presumed systemic infectious disease (1). These findings expand the geographic range of various pathogens of pinnipeds and may be of value to first responders, clinicians, and diagnosticians.

Fish prey of sub-Antarctic fur seals Arctocephalus tropicalis at the Tristan da Cunha Islands, South Atlantic Ocean

Some top predator populations in the South Atlantic and South Indian oceans are in decline, presumably contingent upon reduced food availability, precipitated by climate change. This phenomenon impacts on the positions of major ocean frontal zones which are hypothesised to act as natural dispersal borders for fish in the Southern Ocean. We investigate this hypothesis by establishing the fish diet of sub-Antarctic fur seals, Arctocephalus tropicalis, at Tristan da Cunha Island (37°15′S, 12°25′W) and Gough Island (40°19′S, 9°57′W), South Atlantic Ocean. The diets of these island populations, located on either side of the Subtropical Convergence, are compared with published dietary information from populations further south on islands located within the Polar Frontal Zone. To this end, fur seal scats were collected and analysed for remains of hard parts from prey in 2012–2013. The myctophid fish Gymnoscopelus piabilis, Protomyctophum tenisoni and Symbolophorus barnardi predominated in the diet. Lampichthys gemellarii, Myctophum aurolaternatum, S. barnardi and the Diaphus genus are recorded for the first time in the diet of A. tropicalis. Sub-Antarctic fur seal populations clustered around the Subtropical Convergence (~ 41°40′S), compared with those in the Polar Frontal Zone (~ 47°25′S to ~ 50°47′S), showed a considerable difference in the myctophid fish prey taken. The latitudinal differences in the fish diet of sub-Antarctic fur seals support suggestions that major frontal zones act as natural dispersal borders for fish in the Southern Ocean.

Status of pinnipeds on mid-Atlantic ridge islands, South Atlantic Ocean

The status of pinnipeds on mid-Atlantic ridge islands is reviewed to detect trends that may relate to climate change. Small numbers of southern elephant seals Mirounga leonina breed on Gough Island (40°S, 10°W) and at Bouvetoya (54°24′S, 03°21′E) where numbers remained small over ~ 68 years. Vagrant southern elephant seals wandered farther north to tropical Saint Helena Island (15°57′S, 5°41′W) in historical times but have not been recorded there more recently. This suggests a contraction of their distributional range, as manifested in the decline in numbers to imminent extinction at Gough Island. At Gough Island and at Tristan da Cunha (37°05′S, 12°17′W), leopard seals Hydrurga leptonyx and Antarctic fur seals Arctocephalus gazella are occasional seasonal transients from Antarctic and sub-Antarctic islands and the circumpolar sea ice farther to the south. Large populations of Antarctic fur seals A. gazella and sub-Antarctic fur seals A. tropicalis breed at Bouvetoya and Gough Island, respectively. The current state of both populations is uncertain as other populations of conspecifics in the South Atlantic and South Indian oceans are in decline ostensibly contingent upon reduced food availability, likely precipitated by climate change.

Vagrant sub-Antarctic fur seal at tropical Ascension Island, South Atlantic Ocean

Knowledge of extra-limital movements of seals improves our understanding of species’ dispersal and dispersion abilities and patterns, and perhaps environmental changes. Canvassing and internet literature searches revealed the sighting of a vagrant adult male sub-Antarctic fur seal Arctocephalus tropicalis on the coast adjacent to George Town (7° 56′ S, 14° 25′ W), Ascension Island, in 2010. Although finer details of the sighting are sketchy, this is the first sighting of any seal at Ascension Island, and the northernmost sighting on record for the species on the mid-Atlantic Ridge islands. The likely source of the vagrant is the population at Gough Island (40° 20′ S, 9° 54′ W) some 3624 km further south in the Atlantic. The vagrant likely moved westward from Gough Island to the Brazilian coast, then northwards in coastal waters, eventually reaching Ascension Island.

Myeloid and histiocytic sarcomas in subantarctic fur seals Arctocephalus tropicalis, Brazil

Histopathological and immunohistochemical methods were used to diagnose round cell tumors in 2 subantarctic fur seals Arctocephalus tropicalis with marked anemia. Although wild-born, both individuals were placed under human care while juveniles in a Brazilian aquarium. Both pinnipeds were PCR tested for herpesvirus, and 1 was infected with otariid gammaherpesvirus 5 (OtHV-5), previously described in a subantarctic fur seal stranded in Brazil. Although some gammaherpesviruses can cause sarcomas and other neoplasms, it was not possible to definitively associate OtHV-5 with the neoplasm. To our knowledge, these are the first neoplasm records in subantarctic fur seals.

Sub-Antarctic fur seals depredate northern rockhopper penguins at Nightingale Island, Tristan da Cunha

The most plausible hypothesis for declining population trends of some marine top predators at the northern extent of their breeding ranges in the Southern Ocean is that it results from environmental change. Sub-Antarctic fur seals Arctocephalus tropicalis are opportunistic and pelagic foragers that feed on a variety of fish, cephalopods, and crustaceans throughout their range. Penguins are also targeted, but to what extent remains uncertain, with only two records to date: Amsterdam Island, South Indian Ocean, where they kill and feed on northern rockhopper penguins Eudyptes moseleyi; and Gough Island, the southernmost island in the Tristan da Cunha archipelago, South Atlantic Ocean, where they are suspected to be significant predators of northern rockhopper penguins based on an unprecedented number of penguin carcasses (> 100) found floating at sea in 2011. We report the first documented records of such predations from the northern islands in the Tristan archipelago. Over three austral summers (2015–2017), northern rockhopper penguins with severe injuries were frequently observed at Nightingale Island. The cause of the wounds was unknown, but seal or shark attacks seemed probable. In January 2019, the first confirmed sighting of a sub-Antarctic fur seal, predating a healthy northern rockhopper penguin at sea off Nightingale Island was recorded. It remains uncertain whether the large A. tropicalis population at the Tristan da Cunha islands is significant predators of northern rockhopper penguins, but this could partly explain the significant recent decrease in northern rockhopper penguin population numbers.

What’s in a whisker? High-throughput analysis of twenty-eight C19 and C21 steroids in mammalian whiskers by ultra-performance convergence chromatography-tandem mass spectrometry

Obtaining longitudinal endocrinological data from free-ranging animals remains challenging. Steroid hormones can be extracted sequentially from non-invasively sampled biologically inert keratinous tissues, such as feathers, nails, hair and whiskers. However, uncertainty regarding the type and levels of steroids incorporated into such tissues complicates their utility in wildlife studies. Here, we developed a novel, comprehensive method to analyze fourteen C19 and fourteen C21 steroids deposited chronologically along the length of seal whiskers in a single, 6-minute chromatographic step, using ultra-performance convergence chromatography-tandem mass spectrometry. The limits of detection and quantification ranged from 0.01 to 2 ng/mL and from 0.1 to 10 ng/mL, respectively. The accuracy and precision were within acceptable limits for steroids at concentrations ≥2 ng/mL. The recovery (mean = 107.5% at 200 ng/mL), matrix effect and process efficiency of steroids evaluated, using blanked whisker matrix samples, were acceptable. The method was applied to the analysis of steroid hormone levels in adult female whisker segments obtained from southern elephant seals (Mirounga leonina), n = 10, and two fur seal species, Antarctic fur seals (Arctocephalus gazella; n = 5) and subantarctic fur seals (Arctocephalus tropicalis; n = 5), sampled between 2012 and 2017. In the whisker subsamples analyzed (n = 71), the median concentration of steroid hormones detected above the LOQ ranged from 2.0 to 273.7 pg/mg. This was the first extraction of multiple C19 and C21 steroids, including their C11-oxy metabolites, from the whiskers of mammals. Measuring hormones sequentially along the whisker lengths can contribute to our understanding of the impact of stress associated with environmental/climate changes that affect the health, survival of organisms, as well as to delineate the reproductive cycles of free-living mammals with cryptic life stages.

Toxoplasmosis and Sarcocystis spp. infection in wild pinnipeds of the Brazilian coast.

The protozoans Toxoplasma gondii and Sarcocystis spp. (Sarcocystidae: Apicomplexa) affect a wide variety of vertebrates. Both have been reported to infect pinnipeds, with impacts on health ranging from inapparent to fulminant disease and death. However, little is known regarding their infections and associated pathology in South American pinnipeds. We used histological techniques to survey for the presence of T. gondii and Sarcocystis spp. in 51 stranded pinnipeds from Brazil. Immunohistochemical and molecular assays were employed in those cases consistent with Sarcocystidae infection. T. gondii cysts were detected in the central nervous system and heart of a South American fur seal Arctocephalus australis, associated with meningoencephalitis, myocarditis and endocarditis, and confirmed by immunohistochemistry. Additionally, this animal presented Sarcocystis sp. cysts in brain and heart tissues. Four additional specimens-2 Subantarctic fur seals A. tropicalis, an Antarctic fur seal A. gazella and another South American fur seal-presented intrasarcoplasmic cysts compatible with Sarcocystis spp. in muscle samples. There was no inflammation associated with the Sarcocystis spp. tissue cysts and all cysts were negative for S. neurona immunohistochemistry. The B1 gene of T. gondii was amplified in the 5 pinnipeds infected by Sarcocystidae protozoans. To our knowledge, this is the first report of toxoplasmosis in wild South American pinnipeds and of Sarcocystis spp. in South American fur seals. Detection of terrestrial parasites in aquatic mammals could be an indicator of their presence in the marine environment.

Preferred, small-scale foraging areas of two Southern Ocean fur seal species are not determined by habitat characteristics

BackgroundTo understand and predict the distribution of foragers, it is crucial to identify the factors that affect individual movement decisions at different scales. Individuals are expected to adjust their foraging movements to the hierarchical spatial distribution of resources. At a small local scale, spatial segregation in foraging habitat happens among individuals of closely situated colonies. If foraging segregation is due to differences in distribution of resources, we would expect segregated foraging areas to have divergent habitat characteristics.ResultsWe investigated how environmental characteristics of preferred foraging areas differ between two closely situated Subantarctic fur seal (Arctocephalus tropicalis) colonies and a single Antarctic fur seal (A. gazella) colony that forage in different pelagic areas even though they are located well within each other’s foraging range. We further investigated the influence of the seasonal cycle on those environmental factors. This study used tracking data from 121 adult female Subantarctic and Antarctic fur seals, collected during summer and winter (2009–2015), from three different colonies. Boosted Regression Tree species distribution models were used to determine key environmental variables associated with areas of fur seal restricted search behaviour. There were no differences in the relative influence of key environmental variables between colonies and seasons. The variables with the most influence for each colony and season were latitude, longitude and magnitude of sea-currents. The influence of latitude and longitude is a by-product of the species’ distinct foraging areas, despite the close proximity (< 25 km) of the colonies. The predicted potential foraging areas for each colony changed from summer to winter, reflecting the seasonal cycle of the Southern Ocean. The model predicted that the potential foraging areas of females from the three colonies should overlap, and the fact they do not in reality indicates that factors other than environmental are influencing the location of each colony’s foraging area.ConclusionsThe results indicated that small scale spatial segregation of foraging habitats is not driven by bottom-up processes. It is therefore important to also consider other potential drivers, e.g. competition, information transfer, and memory, to understand animal foraging decisions and movements.

Stalked barnacles on an adult male sub-Antarctic fur seal at Inaccessible Island, Tristan da Cunha

An adult male sub-Antarctic fur seal, Arctocephalus tropicalis, on Inaccessible Island in the Tristan da Cunha archipelago (TdC), was observed infested with goose barnacles, likely Lepas australis. Although adult females have been recorded to carry goose barnacles, this is the first record from an adult male at a breeding island. Males remain at sea throughout winter, so it is not clear why there are not more records of goose barnacles attached to their pelage.