Fur Seals Research Articles

Drones reveal spatial patterning of sympatric Alaskan pinniped species and drivers of their local distributions

The Arctic and its adjacent ecosystems are undergoing rapid ecological reorganization in response to the effects of global climate change, and sentinel species provide critical updates as these changes unfold. This study leverages emerging remote sensing techniques to reveal fine-scale drivers of distribution and terrestrial habitat use of two sympatric sentinel species of the central Bering Sea, the Pacific harbor seal (Phoca vitulina richardii (Gray, 1864)) and the northern fur seal (Callorhinus ursinus (Linnaeus, 1758)), at non-breeding haul-outs in the Pribilof Islands. We surveyed these species using unoccupied aircraft systems with thermal and visible-light photography, and we applied distributional modeling techniques to quantify the relative influence of habitat characteristics and social dynamics on the local distributions of these species. Drone imagery yielded locations and population counts of each species, and spatial data products allowed quantitative characterization of occupied sites, revealing that conspecific attraction is a driver of local site selection for both species, and Pacific harbor seals and northern fur seals are differentially limited by terrain characteristics. These findings represent new applications of species distribution modeling at local scales, made possible by ultra-high resolution drone surveillance and photogrammetric techniques, which add new spatial context to past observations and future scenarios in this changing ecosystem.

Understanding the zoonotic pathogen, Coxiella burnetii in Australian fur seal breeding colonies through environmental DNA and genotyping

Context Coxiella burnetii is suspected as a novel pathogen contributing to decreased pup production in Australian fur seals (Arctocephalus pusillus doriferus). It has recently been described from a single breeding colony in Bass Strait, has previously been associated with two decreasing populations of northern hemisphere pinnipeds and is a known reproductive pathogen. Data around its disease ecology in marine mammals are sparse. Aims To determine whether environmental DNA (eDNA) can be used to survey for C. burnetii in Australian fur seal breeding colonies. To determine whether C. burnetii in Australian fur seals is the same genotype as terrestrial Australian C. burnetii. Methods Soil samples were collected from Kanowna Island and Seal Rocks. Placental samples were collected from Kanowna Island. Soil was evaluated for eDNA using a quantitative polymerase chain reaction (qPCR) for com1 gene. Placental samples were evaluated with com1, htpAB and IS1111 markers. Multiple-locus variable number of tandem repeats analysis for three microsatellite loci (ms-24, ms-28 and ms-33) was used to determine relatedness to Australian C. burnetii genotypes. Key results eDNA results varied between pre-and post-pupping at Seal Rocks. When targeting the com1 gene, the post-pupping prevalence at Kanowna Island and Seal Rocks was 59.6% and 90%, respectively. eDNA PCR inhibition of samples was low at 1.9%. There was very poor, sporadic to absent IS1111 amplification in placental samples. The com1 and htpAB qPCRs had an overall prevalence across placental samples of 39.2% and 56.7% respectively. In 90.1% of placental samples (n = 11), the ms-28 locus amplified. Neither ms-24 nor ms-33 amplified. Conclusions eDNA is an effective tool to survey Australian fur seal breeding colonies in the post-pupping period for C. burnetii. The prevalence appears to be much higher in the Seal Rocks colony than in the Kanowna Island colony. It appears that this is not a terrestrial Australian genotype but rather closely related to genotypes detected in marine mammals in the northern hemisphere. Implications This research significantly expands our ability to survey for C. burnetii in Australian fur seals and other marine mammals. It highlights knowledge gaps in our understanding of the disease ecology and phylogeny of C. burnetii in marine mammals.

The Moscow Embassy of George Kennan and American Diplomacy in the Cold War

This paper studies the operations of the Embassy of the United States of America in Moscow headed by G. F. Kennan (May — September 1952) in the context of Cold War diplomatic history. Based on an analysis of documents located in the Archive of the Foreign Policy of the Russian Federation, this study focuses on such key international issues as peaceful settlement of the Korean war, resolution of the German issue, and the signing of a treaty protecting fur seals in the Pacific basin. This article highlights the role of the American Embassy in Moscow, and of Ambassador Kennan in particular, in the discussion of these issues, and the nature of the embassy staff members’ interactions with Soviet authorities. The archival materials concerning the Soviet-American relations in 1952 provide clear evidence that the diplomatic corps faced severe difficulties under the conditions of military and political confrontation of the Cold War. The paper also elucidates the reasons for declaring Kennan persona non grata. Finally, the author considers the influence of the Moscow ambassadorship on Kennan’s perception of communism and the Soviet social system. He became convinced not only of the Soviet political system’s bureaucratic inertia and clumsiness, its excessive centralization, and its total focus on Stalin’s personality, but also of the extreme straightforwardness and uncompromising nature of American foreign policy towards the Soviet Union.

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.

Ecosystem shifts inferred from long-term stable isotope analysis of male Antarctic fur seal Arctocephalus gazella teeth

The Atlantic sector of the Southern Ocean has been rapidly changing over the last century. Many of those changes are driven by climate anomalies such as the El Niño-Southern Oscillation and the Southern Annular Mode, which affect biological processes that scale up the food web. We used δ13C and δ15N time series of dentine growth layer groups (as a proxy of individual foraging history from multiple years, n = 41 teeth) to assess temporal shifts in foraging habits of subadult/adult male Antarctic fur seals Arctocephalus gazella (AFSs) in 2 areas of high concentration of Antarctic krill Euphausia superba: the South Shetland Islands and the South Orkney Islands. Our analyses, which represent the first long-term isotopic assessment of male AFS sampled in Antarctic waters, revealed a significant decrease of δ13C (0.04‰ yr-1) from 1974 to 2015 and a decrease of δ15N after the late 1990s. The observed changes are likely driven by shifts in latitudinal and longitudinal distribution of krill and increased incorporation of 15N-enriched sources (higher trophic level prey and/or feeding in different areas) in the most recent period for reasons that are not yet clear. We were able to trace ecosystem changes through isotopic bio-archives of Antarctic fur seals, highlighting the role of this species as an ecosystem indicator of the trophic cascade effects caused by climate change in the Southern Ocean.

The role of different age and sex groups of Callorchinus ursinus in the life cycle of Uncinaria lucasi

One of the most pathogenic helminth species for the young of the northern fur seal (Callorchinus ursinus) is the nematode (Ancylostomatidae family) Uncinaria lucasi. The ecology of the definitive host determines the adaptation of the parasite to the host, the development of additional transmission mechanisms. The main adaptation of the parasite to the host is the ability of invasive larvae to settle in the tissues of all sex and age groups of the seal herd, which makes it possible to avoid wintering in the ground. At present, the fate of these larvae is unknown, as well as the role of each of the age groups of seals in the implementation of the life cycle of this helminthiasis, in connection with which the purpose of the work was to determine the role of the sex and age groups of the seal herd to maintain the hostparasitic system of the seal – uncinaria. The study found that female northern fur seals are a mandatory link in the life cycle of U. lucasi and they should be considered as.

The Relevance of Skilled In-water Guides in Swim-With Wildlife Tours

Commercial in-water interactions (IWIs) with wildlife may hold potential risks for their participants. Precautionary mechanisms for mitigating such risk factors are crucial for safe human–wildlife encounters. One of those tools is the provision of skilled in-water guides, yet across the industry it is not a standard practice. This article communicates the relevance of in-water guides for the safety and well-being of tour participants, substantiated by semistructured interview data obtained in three case study locations in the South Pacific. Participants interacting with humpback whales (Megaptera novaeangliae), New Zealand fur seals (Arctocephalus forsteri), and bull sharks (Carcharhinus leucas) reported various benefits from the presence of in-water guides, including anxiety relief, elevated confidence and perception of safety, and obtainment of information on animal behavior. Apart from tourist safety, a deployment of in-water guides would also constitute an effective way of managing inappropriate tourist behavior. Hence, the results of this study strongly suggest the inclusion of in-water guides in commercial operations for tourist safety and management in future licensing schemes.

MEASUREMENT OF INTRAOCULAR PRESSURE USING REBOUND TONOMETRY IN ANESTHETIZED PERUVIAN FUR SEALS (ARCTOCEPHALUS AUSTRALIS) FROM PUNTA SAN JUAN, PERU.

Ocular disease in pinnipeds under human care is well described, and intraocular pressure (IOP) can be impacted by a variety of ophthalmic conditions. Species-specific reference parameters from clinically normal animals are instrumental for understanding how ophthalmic diseases may impact ocular pressures. IOP measurements were obtained using rebound tonometry from free-ranging Peruvian fur seals (Arctocephalus australis unnamed subspecies) at Punta San Juan, Peru, over a 6-yr period (2010-2016). Retrospective data obtained from 108 (81 adults and 27 neonates comprising 69 females and 39 males) anesthetized fur seals with normal anterior segment ophthalmic examinations was included in the analysis. Differences in IOP from each eye were compared to categorical variables (age, year, sex, restraint) using an independent-samples t test. All univariate results with a significance of P < 0.05 were included in multivariate analysis. Of the 13 general linear models evaluated, the top two for both the right and the left eye included age class when all variables were evaluated simultaneously. Neonates had significantly lower IOP values than adults in both the right eye (17.5 mm Hg; 95% confidence interval [CI]: 14.0-21.1 mm Hg compared to 33.5 mm Hg; 95% CI: 31.0-36.1 mm Hg, respectively) and the left eye (18.4 mm Hg; 95% CI: 14.4-22.5 mm Hg compared to 32.3 mm Hg; 95% CI: 29.3-35.3 mm Hg, respectively). Anesthesia method was not statistically significant (P > 0.05). This is the first report of normal IOP measurements for any fur seal species. Described data can be used to improve diagnosis and management of ocular alterations in pinnipeds.

Feel the beat: cape fur seal males encode their arousal state in their bark rate.

The cape fur seal is one of the most colonial mammal species in the world. Breeding colonies are composed of harems held by mature males (older than 10years) with up to 30 females and their pups, while roaming subadult males (younger and socially immature) are kept away from bulls' territories. As in other pinnipeds, cape fur seals are highly vocal and use acoustic signals in all their social interactions. Males produce barks-short vocalizations always produced in sequences-for territorial defense, mating behaviors, and agonistic interactions. These calls convey information about the sex, age class, and individual identity. This study investigated whether motivational cues such as the arousal state can be encoded in territorial males' barks and whether these cues are decoded by listening sub-adult males. The rate (number of calls per unit of time) and fundamental frequency of barks were found to significantly increase during high arousal state interactions (i.e., male-male confrontation) compared to spontaneous barks. Playback experiments revealed that subadult males responded with a higher level of vigilance when territorial males' barks had a faster bark rate. This mechanism of decoding the bulls' arousal state from barks will likely constitute an advantage for both bulls and the subadult males, by avoiding or reducing physical conflicts, and thereby reducing energy expenditure and the risk of injury. This study is the first experimental evidence of cape fur seals' using vocal rhythmic patterns to modulate their social interactions.

The cost of a meal: factors influencing prey profitability in Australian fur seals.

Knowledge of the factors shaping the foraging behaviour of species is central to understanding their ecosystem role and predicting their response to environmental variability. To maximise survival and reproduction, foraging strategies must balance the costs and benefits related to energy needed to pursue, manipulate, and consume prey with the nutritional reward obtained. While such information is vital for understanding how changes in prey assemblages may affect predators, determining these components is inherently difficult in cryptic predators. The present study used animal-borne video data loggers to investigate the costs and benefits related to different prey types for female Australian fur seals (Arctocephalus pusillus doriferus), a primarily benthic foraging species in the low productivity Bass Strait, south-eastern Australia. A total of 1,263 prey captures, resulting from 2,027 prey detections, were observed in 84.5 h of video recordings from 23 individuals. Substantial differences in prey pursuit and handling times, gross energy gain and total energy expenditure were observed between prey types. Importantly, the profitability of prey was not significantly different between prey types, with the exception of elasmobranchs. This study highlights the benefit of animal-borne video data loggers for understanding the factors that influence foraging decisions in predators. Further studies incorporating search times for different prey types would further elucidate how profitability differs with prey type.

Environmental drivers of foraging behaviour during long-distance foraging trips of male Antarctic fur seals

Animals may use long-distance foraging trips to capitalize on spatiotemporal variation in food availability, allowing individuals to maximize resource gain from foraging effort. This is particularly important for dimorphic species with polygynous mating where males face strong selection pressures to attain large size and access to reproductive females. We tracked 17 male Antarctic fur seals, Arctocephalus gazella , during their prolonged postbreeding trips and assessed links between their movements and environmental predictors of profitable feeding areas. Males made one of two types of trips: a long trip to the Antarctic ice edge or shorter trips to areas where the southern Antarctic Circumpolar Current fronts generate high biological activity. The trip type was not determined by body size but was related to departure date from the breeding area, suggesting that males must trade off opportunities at the breeding area (reproductive, social interactions) and foraging opportunities between breeding seasons. Regardless of trip structure, males focused search effort far from foraging areas of central-place foraging seabirds and seals including female Antarctic fur seals provisioning offspring. Males showed clear spatiotemporal patterns in dive behaviour, with deep dives in shelf waters during the day and predominantly shallower dives in pelagic waters at night. Diel dive patterns showed monthly changes in photoperiod and lunar phase, consistent with feeding on vertically migrating prey. However, males did not use area-restricted search to focus dive effort, instead performing a mix of foraging and nonforaging behaviour within and between restricted search areas. We discuss the scale and type of inference that can be made from movement models, given the behavioural constraints that govern long-distance trips in vast, heterogeneous environments like the Southern Ocean. • Males made two types of long-distance trip, related to departure date not body size. • Foraging and nonforaging behaviour occurred throughout these trips. • Males foraged mostly away from breeding seals, in areas of high biological activity. • Diel dive behaviour aligned with changes in solar and lunar light.

Fluctuations in serum steroid hormone concentrations and body mass during growth and sexual maturation in captive northern fur seals (Callorhinus ursinus).

Northern fur seals (Callorhinus ursinus) have a distinct life history pattern comprising annual terrestrial breeding and oceanic migration, and the physiological changes associated with these patterns are of particular interest for understanding their environmental adaptations. However, owing to their oceanic distribution, limited information is available on the reproductive physiology of wild individuals during the immature stage and the winter migration period. This study aimed to determine the relationships among the seasonal hormone profiles, body growth, age, and pregnancy using monthly serum samples collected over 3–5 years from two male and two female captive individuals during pubescence and sexual maturation. Small increases in the serum testosterone signaled puberty in males aged 3 and 4 years. Thereafter, males showed considerable increases in testosterone during breeding seasons, indicating sexual maturity. Immature female serum progesterone was maintained at low levels, but after pubescence, females showed an increase in serum progesterone in August, the month next to the peak of delivery, followed by a decrease. In non-pregnant females, progesterone did not increase significantly until the next breeding season, but in pregnant females, they increased again from February to March and then gradually decreased. Immature males increased body mass constantly and reached puberty when their body mass exceeded 20 kg, and they showed seasonal weight fluctuations after puberty. These results provide fundamental information for determining sexual maturity and pregnancy in this species based on sex steroid hormones and body mass measurements.

Night on Earth

Night on Earth

Predatory species left stranded following the collapse of the sardine Sardinops sagax (Pappe, 1854) stock off the northern Benguela upwelling system: A review

Sardine Sardinops sagax (Pappe, 1854) is an important forage species, in the northern Benguela Upwelling System (nBUS). Sardine was a key forage species of the pelagic component in the nBUS, but the population collapsed due to a combination of overfishing and ecosystem change and variability in the nBUS. Multiple predators depended on sardine as high-quality food at the time when it was abundant. This study reviewed the current knowledge of predators' diet pre- and post-collapse of the sardine population stock in the nBUS. Data were sourced from previous studies on the trophic interaction in the nBUS. The historical and contemporary diets of commercially exploited species that prey on sardine were found to be relatively well documented while there are data deficiencies for non-commercially exploited species including cetaceans, sharks and some non-commercially exploited fish species. Amongst the species most reliant on sardine as prey are African penguin Spheniscus demersus, Cape gannet Morus capensis, Cape cormorant Phalacrocorax capensis, Cape monkfish Lophius vomerinus, shallow-water hake Merluccius capensis, deep-water hake M. paradoxus, snoek Thyrsites atun, Albacore tuna Thunnus alalunga, Cape fur seal Arctocephalus pusillus, Common dolphins Delphinus delphis, Dusky dolphins Lagenorhynchus obscurus, Heaviside's dolphins Cephalorhynchus heavisidii, six gills shark Hexanchus griseus, copper sharks Carcharhinus brachyurus, school shark Galeorhinus galeus and pelagic sharks Prionace glauca. Some predatory species such as the African penguin, Cape cormorant, Cape gannet, and school shark, are considered endangered as per the International Union for the Conservation of Nature (IUCN) Red List criteria. Populations of Albacore tuna and Cape monkfish are near threatened, while Cape fur seals, common dolphins, and shallow-water hake are considered the least concerned on the IUCN list. Although the collapse of sardine has affected the food webs it has not resulted in collapse, rather there have been changes. Three prey species; bearded goby, Cape horse mackerel, and jellyfish, were identified as alternative prey for some of the predators that previously fed on sardine. This review showed how overexploitation of sardine could have had far-reaching effects on the nBUS through feeding linkages. Goby, although a low-quality prey, is a successful substitute for sardine probably mostly due to its high abundance, tolerance to low oxygen and ability to thrive in warm waters. However, further studies are needed to establish the strength of the ecological linkages of the prey species that replaced sardine in the diets of the predators.

Peruvian Fur Seals as Archivists of El Niño Southern Oscillation Effects

Peru’s coastal waters are characterized by significant environmental fluctuation due to periodic El Niño- La Niña- Southern Oscillation (ENSO) events. This variability results in ecosystem-wide food web changes which are reflected in the tissues of the Peruvian fur seal (Arctocephalus australis). Stable isotope ratios (δ13C and δ15N) in Peruvian fur seal vibrissae (whiskers) are used to infer temporal primary production and dietary variations in individuals. Sea surface temperature anomaly (SSTA) recordings from the Niño 1+2 Index region captured corresponding ENSO conditions. Fluctuations in δ15N values were correlated to SSTA records, indicating that ENSO conditions likely impact the diet of these apex predators over time. Anomalous warm phase temperatures corresponded to decreased δ15N values, whereas cold phase anomalous conditions corresponded to increased δ15N values, potentially from upwelled, nutrient-rich water. Vibrissae δ13C values revealed general stability from 2004 to 2012, a moderate decline during 2013 (La Niña conditions) followed by a period of increased values concurrent with the 2014–2016 El Niño event. Both δ13C and δ15N values were inversely correlated to each other during the strongest El Niño Southern Oscillation event on record (2014–2016), possibly indicating a decline in production leading to an increase in food web complexity. Lower δ13C and δ15N values were exhibited in female compared to male fur seal vibrissae. Findings suggest ENSO conditions influence resource availability, possibly eliciting changes in pinniped foraging behavior as well as food web of the endangered Peruvian fur seal.

Winter distribution of juvenile and sub-adult male Antarctic fur seals (Arctocephalus gazella) along the western Antarctic Peninsula

Detailed knowledge of habitat use by marine megafauna is critical to understand their ecological roles and for the adequate management of marine resources. Antarctic fur seals (Arctocephalus gazella) inhabiting the Atlantic sector of the Southern Ocean prey largely on Antarctic krill (Euphausia superba) and play a central role in managing the krill fishery. Here, we assessed the demographic structure of three post-mating, early moult male haul-outs in the South Shetland Islands in early March and calculated the relative contribution of juveniles (1–4 years old) and sub-adult males (5–6 years) to the population remaining in maritime Antarctica after the breeding season. We also satellite tagged 11 juvenile males and four sub-adult males to analyze their movements and develop a species distribution model including both age classes. Our results highlighted the dominance of young individuals in the male population, revealed that they do not behave as central place foragers and identified key environmental drivers that affected their distribution at-sea throughout winter. Predicted potential foraging habitat overlapped highly with the known distribution of Antarctic krill, and identified the waters off the western Antarctic Peninsula and the Scotia Sea as the core of the distribution area of juvenile and sub-adult male Antarctic fur seals in winter. This pattern is similar to that of adult males but totally different from that of adult females, as the latter overwinter in areas at latitude 45–55° S. This segregation has implications for the ecology and management of the krill fishery.

Seroprevalence of Toxoplasma gondii in Pinnipeds under Human Care and in Wild Pinnipeds.

Toxoplasma gondii infection has been reported in numerous species of marine mammals, some of them with fatal consequences. A serosurvey for T. gondii infection was conducted in pinnipeds from an oceanographic park in Portugal (n = 60); stranded pinnipeds on the Portuguese coast (n = 10); and pinnipeds captured in Lorenzensplate, Germany (n = 99). Sera from 169 pinnipeds were tested for the presence of antibodies to T. gondii by the modified agglutination test with a cut-off titre of 25. An overall seroprevalence of 8.9% (95% confidence interval: 5.1–14.2) was observed. Antibody titres of 25, 50, 100, 1600 and ≥3200 were found in five (33.3%), two (13.3%), five (33.3%), one (6.7%) and two (13.3%) animals, respectively. Pinnipeds under human care had a seroprevalence of 20.0% (12/60), in contrast to 2.8% (3/109) in wild pinnipeds (p < 0.001). General results suggest a low exposure of wild pinnipeds to T. gondii, while the seroprevalence found in pinnipeds under human care highlights the importance of carrying out further studies. This is the first serological survey of T. gondii in pinnipeds in Portugal and the first infection report in South African fur seal (Arctocephalus pusillus pusillus).

Comparative Study of the Gut Microbiota Among Four Different Marine Mammals in an Aquarium.

Despite an increasing appreciation in the importance of host–microbe interactions in ecological and evolutionary processes, information on the gut microbial communities of some marine mammals is still lacking. Moreover, whether diet, environment, or host phylogeny has the greatest impact on microbial community structure is still unknown. To fill part of this knowledge gap, we exploited a natural experiment provided by an aquarium with belugas (Delphinapterus leucas) affiliated with family Monodontidae, Pacific white-sided dolphins (Lagenorhynchus obliquidens) and common bottlenose dolphin (Tursiops truncatus) affiliated with family Delphinidae, and Cape fur seals (Arctocephalus pusillus pusillus) affiliated with family Otariidae. Results show significant differences in microbial community composition of whales, dolphins, and fur seals and indicate that host phylogeny (family level) plays the most important role in shaping the microbial communities, rather than food and environment. In general, the gut microbial communities of dolphins had significantly lower diversity compared to that of whales and fur seals. Overall, the gut microbial communities were mainly composed of Firmicutes and Gammaproteobacteria, together with some from Bacteroidetes, Fusobacteria, and Epsilonbacteraeota. However, specific bacterial lineages were differentially distributed among the marine mammal groups. For instance, Lachnospiraceae, Ruminococcaceae, and Peptostreptococcaceae were the dominant bacterial lineages in the gut of belugas, while for Cape fur seals, Moraxellaceae and Bacteroidaceae were the main bacterial lineages. Moreover, gut microbial communities in both Pacific white-sided dolphins and common bottlenose dolphins were dominated by a number of pathogenic bacteria, including Clostridium perfringens, Vibrio fluvialis, and Morganella morganii, reflecting the poor health condition of these animals. Although there is a growing recognition of the role microorganisms play in the gut of marine mammals, current knowledge about these microbial communities is still severely lacking. Large-scale research studies should be undertaken to reveal the roles played by the gut microbiota of different marine mammal species.

Establishing a reference interval for acute phase proteins, cytokines, antioxidants and commonly measured biochemical and hematologic parameters in the northern fur seal (Callorhinus ursinus)

Over the past several decades there has been a precipitous decline of northern fur seals (Callorhinus ursinus; NFS) at their breeding grounds on the Pribilof Islands in the Bering Sea. The cause of this decline is likely multifactorial and could include changes in environmental parameters, prey abundance and distribution as well as exposure to pathogens and pollutants. Evaluation of inflammatory markers and antioxidant levels of the current population of fur seals in addition to hematologic and biochemical profiles could provide important information regarding health and subclinical or clinical disease in this population. Serum and plasma samples were obtained from clinically healthy adult female NFS and references intervals were determined for multiple parameters that can be altered in response to the presence of disease and environmental stressors. We established a reference interval for cytokines involved in acute inflammation and infection (TNFa, IL1, IL6, IL8, KC, IL10, C-reactive Protein) by utilizing commercially available canine cross-reactive antibodies. Reference intervals were also established for reactive oxygen species (hydrogen peroxide and malondialdehyde), as well as antioxidant levels (vitamin E and selenium) and acute phase proteins evaluated by serum electrophoresis. To improve the ability to compare and interpret indicators of health and disease in this species, we developed reference intervals for commonly utilized hematologic and biochemical tests in addition to the aforementioned markers of oxidative stress and inflammatory biomarkers. There were several animals identified as outliers indicating that they may have had subclinical illness or inflammation. Further investigation utilizing these tests in clinically ill animals and comparison to animals that exhibit normal behavior and no overt signs of illness could increase our understanding of the utility of measuring these parameters in this species.

Mercury and stable carbon and nitrogen isotopes in the natal Fur of two Antarctic pinniped species

Southern elephant seal (SES) and Antarctic fur seal (AFS) are short Southern Ocean food web top predators and are spatial and temporal trend bioindicators of Antarctic Hg bioavailability. Hg, stable isotope composition (δ13C and δ15N) and trophic position (TP) regarding sex were determined using lanugo samples from Antarctic pinnipeds pups (SES n = 35 and AFS n = 11). Hg concentrations in over 50% of the SES pups (mean 5.9 ± 3.1 mg kg−1 dry wt.) are compatible with those found to cause neurologic damage to polar bears in the Arctic. No significant differences regarding sexes for SES or AFS are found based on mean Hg concentrations normalized by body weight. δ15N values and TPs are similar among both species, indicating that gestating SES and AFS mothers feed at the same trophic level. Significantly different δ13C values were found, indicating distinct feeding grounds for mothers belonging to both species when pup lanugo is formed in utero; while SES females like to feed in Antarctic waters, AFS females remain in sub-Antarctic waters. The differences in Hg and δ13C observed for both species reflect not only contrasting feeding habits and anthropogenic Hg inputs, but also maternal foraging strategies.