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primary intracranial fibrosarcoma in a southern sea otter enhydra lutris nereis.southern sea otters enhydra lutris nereis, a threatened marine mammal species, face numerous environmental and infectious disease challenges in their native habitat of coastal california, usa. however, there are few published cases describing neoplasia in sea otters despite their relatively long life span when cared for in aquarium settings. an 18 yr old neutered male southern sea otter, born and raised in human care, presented with an acute onset of seizures and dull mentation. magnetic resonan ...202032213668
seasonal and spatial variation in toxoplasma gondii contamination in soil in urban public spaces in california, united states.toxoplasma gondii is a zoonotic parasite that can have severe implications for human health. acutely infected cats shed environmentally resistant t. gondii oocysts in their faeces that contaminate soil, and soil can serve as a reservoir of infection for humans. free-roaming domestic cats are thought to play an important role in environmental contamination with t. gondii, but few studies have directly measured the direct contribution of free-roaming cats to t. gondii in soil.202031677251
adaptations for amphibious vision in sea otters (enhydra lutris): structural and functional observations.sea otters (enhydra lutris) are amphibious mammals that maintain equal in-air and underwater visual acuity. however, their lens-based underwater accommodative mechanism presumably requires a small pupil that may limit sensitivity across light levels. in this study, we consider adaptations for amphibious living by assessing the tapetum lucidum, retina, and pupil dynamics in sea otters. the sea otter tapetum lucidum resembles that of terrestrial carnivores in thickness and fundic coverage. a heavi ...202032666146
isolation, characterization, and ecotoxicological application of marine mammal skin fibroblast cultures.marine mammal cell cultures are a multifunctional instrument for acquiring knowledge about life in the world's oceans in physiological, biochemical, genetic, and ecotoxicological aspects. we succeeded in isolation, cultivation, and characterization of skin fibroblast cultures from five marine mammal species. the cells of the spotted seal (phoca largha), the sea lion (eumetopias jubatus), and the walrus (odobenus rosmarus) are unpretentious to the isolation procedure. the sea otter (enhydra lutri ...202033078324
trophic downgrading reduces spatial variability on rocky reefs.trophic downgrading in coastal waters has occurred globally during recent decades. on temperate rocky reefs, this has resulted in widespread kelp deforestation and the formation of sea urchin barrens. we hypothesize that the intact kelp forest communities are more spatially variable than the downgraded urchin barren communities, and that these differences are greatest at small spatial scales where the influence of competitive and trophic interactions is strongest. to address this, benthic commun ...202033093542
keystone predators govern the pathway and pace of climate impacts in a subarctic marine ecosystem.predator loss and climate change are hallmarks of the anthropocene yet their interactive effects are largely unknown. here, we show that massive calcareous reefs, built slowly by the alga clathromorphum nereostratum over centuries to millennia, are now declining because of the emerging interplay between these two processes. such reefs, the structural base of aleutian kelp forests, are rapidly eroding because of overgrazing by herbivores. historical reconstructions and experiments reveal that ove ...202032913100
robust age estimation of southern sea otters from multiple morphometrics.reliable age estimation is an essential tool to assess the status of wildlife populations and inform successful management. aging methods, however, are often limited by too few data, skewed demographic representation, and by single or uncertain morphometric relationships. in this study, we synthesize age estimates in southern sea otters enhydra lutris nereis from 761 individuals across 34 years of study, using multiple noninvasive techniques and capturing all life stages from 0 to 17 years of ag ...202032884643
olfaction at depth: cribriform plate size declines with dive depth and duration in aquatic arctoid carnivorans.it is widely accepted that obligate aquatic mammals, specifically toothed whales, rely relatively little on olfaction. there is less agreement about the importance of smell among aquatic mammals with residual ties to land, such as pinnipeds and sea otters. field observations of marine carnivorans stress their keen use of smell while on land or pack ice. yet, one dimension of olfactory ecology is often overlooked: while underwater, aquatic carnivorans forage "noseblind," diving with nares closed, ...202032760503
canine distemper virus in the sea otter (enhydra lutris) population in washington state, usa.before 2001, all serosurveys for morbilliviruses in sea otters (enhydra lutris) in california, washington, and alaska, usa, documented a 0% seroprevalence. the first published serologic detections of morbillivirus in sea otters occurred in 2001-02 in live-captured washington sea otters, with a documented 80% seroprevalence. we conducted a retrospective study of sea otter cases from 1989 to 2010 compiled at the us geological survey, national wildlife health center to identify cases of morbillivir ...202032609600
cascading social-ecological costs and benefits triggered by a recovering keystone predator.predator recovery often leads to ecosystem change that can trigger conflicts with more recently established human activities. in the eastern north pacific, recovering sea otters are transforming coastal systems by reducing populations of benthic invertebrates and releasing kelp forests from grazing pressure. these changes threaten established shellfish fisheries and modify a variety of other ecosystem services. the diverse social and economic consequences of this trophic cascade are unknown, par ...202032527830
missing link: california rock crabs serve as intermediate hosts for the parasite helicometrina nimia.parasites can have strong effects on invertebrate host behaviour, fecundity and survival in marine ecosystems. however, parasites are often poorly documented and still rarely integrated into marine ecological modelling; comprehensive surveys of infection in marine invertebrates are sporadic at best. for example, rock crabs are an important part of californian coastal ecosystems, both as regulators of mussel populations and non-native species, and as prey items for predators like sea otters, but ...202032281537
reductions in the dietary niche of southern sea otters (enhydra lutris nereis) from the holocene to the anthropocene.the sea otter (enhydra lutris) is a marine mammal hunted to near extinction during the 1800s. despite their well-known modern importance as a keystone species, we know little about historical sea otter ecology. here, we characterize the ecological niche of ancient southern sea otters (e. lutris nereis) using δ13c analysis and δ15n analysis of bones recovered from archaeological sites spanning ~7,000 to 350 years before present (n = 112 individuals) at five regions along the coast of california. ...202032273989
long-term ecological impacts from oil spills: comparison of exxon valdez, hebei spirit, and deepwater horizon.the long-term ecological impacts of the exxon valdez oil spill (evos) are compared to two extensively studied and more recent large spills: deepwater horizon (dwh) and the hebei spirit oil spill (hsos). each of the three spills differed in magnitude and duration of oil released, environmental conditions, ecological communities, response and clean up measures, and ecological recovery. the evos began on march 24, 1989, and released 40.8 million liters of alaska north slope crude oil into the cold, ...202032267150
novel infections of corynosoma enhydri and profilicollis sp. (acanthocephala: polymorphidae) identified in sea otters enhydra lutris.infectious disease is a major cause of mortality for sea otters enhydra lutris, a keystone species of continued concern for conservationists. parasitic infection has long been identified as a cause of mortality in otters in both alaska and california, usa. corynosoma enhydri (acanthocephala) is the only parasite that uses sea otters as its primary definitive host and is highly prevalent in otter populations; however, it is generally considered unimportant both pathologically and ecologically, al ...202032132276
spatial epidemiological patterns suggest mechanisms of land-sea transmission for sarcocystis neurona in a coastal marine mammal.sarcocystis neurona was recognised as an important cause of mortality in southern sea otters (enhydra lutris nereis) after an outbreak in april 2004 and has since been detected in many marine mammal species in the northeast pacific ocean. risk of s. neurona exposure in sea otters is associated with consumption of clams and soft-sediment prey and is temporally associated with runoff events. we examined the spatial distribution of s. neurona exposure risk based on serum antibody testing and assess ...202032111856
use of the acth challenge test to identify the predominant glucocorticoid in the southern sea otter (enhydra lutris nereis).after nearly being hunted to extinction during the fur trade of the late 20th century, sea otter (enhydra lutris) populations have recovered to varying degrees of their historical range. while overall population numbers and range have increased, there are regions in which expansion has occurred at a slower rate and/or animal numbers have decreased, which may be a result of chronic stress from a variety of sources. some have employed glucocorticoid analysis in their attempts to validate these exp ...202032038847
leptospirosis in northern sea otters (enhydra lutris kenyoni) from washington, usa.we diagnosed leptospirosis in six northern sea otters (enhydra lutris kenyoni) that stranded on beaches in washington state, us in 2002. significant gross findings included cyanotic oral mucous membranes, renal swelling, congestion or pale streaks on the cut surface of renal lobules, hematuria, dehydration, lymphadenopathy, pulmonary congestion, and rarely adrenal hemorrhage and congestion. histopathology showed lymphoplasmacytic tubulointerstitial nephritis with intraluminal spirochetes and imm ...202031880990
first draft genome of the sable, martes zibellina.members of genus martes provide early warning signals about forest ecosystem health and are designated as a management indicator species. as one of the most widespread members in martes, the sable (martes zibellina) is a circumboreal small predator found throughout all taiga zoogeographical zones of eurasia and shows distinct population differentiation and morphological variations. to support further studies on striking local adaptation and population evolution, we present the first sable genome ...202032058545
aquatic adaptation and depleted diversity: a deep dive into the genomes of the sea otter and giant otter.despite its recent invasion into the marine realm, the sea otter (enhydra lutris) has evolved a suite of adaptations for life in cold coastal waters, including limb modifications and dense insulating fur. this uniquely dense coat led to the near-extinction of sea otters during the 18th-20th century fur trade and an extreme population bottleneck. we used the de novo genome of the southern sea otter (e. l. nereis) to reconstruct its evolutionary history, identify genes influencing aquatic adaptati ...201931212313
there and back again - the return of the nasal mite halarachne halichoeri to seals in german waters.the nasal mite halarachne halichoeri (acari; halarachnidae) is adapted to live in the marine environment with pinnipeds as its primary host and can cause different levels of upper respiratory disease in both harbour seals (phoca vitulina) and grey seals (halichoerus grypus). historical reports of h. halichoeri occurring in seals from german waters date back to the end of the 19th century. however, with the disappearance of the grey seal from german waters as a consequence of human over-exploitat ...201931061792
pathology and epidemiology of nasopulmonary acariasis (halarachne sp.) in southern sea otters (enhydra lutris nereis).halarachne sp. nasal mites infest harbor seals (phoca vitulina) and southern sea otters (enhydra lutris nereis) in california, but little is known about the pathophysiology of these infestations, or risk factors for exposure. to investigate these questions, a retrospective case-control study was performed using necropsy data from 70 mite-infested sea otters, and 144 non-infested controls. case records for sea otters examined by pathologists from february 1999 through may 2015 were examined to as ...201931011527
species recovery and recolonization of past habitats: lessons for science and conservation from sea otters in estuaries.recovering species are often limited to much smaller areas than they historically occupied. conservation planning for the recovering species is often based on this limited range, which may simply be an artifact of where the surviving population persisted. southern sea otters (enhydra lutris nereis) were hunted nearly to extinction but recovered from a small remnant population on a remote stretch of the california outer coast, where most of their recovery has occurred. however, studies of recentl ...201931844568
sea otters shown to have low genetic diversity. 201931584653
dry versus wet and gross: comparisons between the dry skull method and gross dissection in estimations of jaw muscle cross-sectional area and bite forces in sea otters.bite force is a measure of feeding performance used to elucidate links between animal morphology, ecology, and fitness. obtaining live individuals for in vivo bite-force measurements or freshly deceased specimens for bite force modeling is challenging for many species. thomason's dry skull method for mammals relies solely on osteological specimens and, therefore, presents an advantageous approach that enables researchers to estimate and compare bite forces across extant and even extinct species. ...201931513299
type x strains of toxoplasma gondii are virulent for southern sea otters (enhydra lutris nereis) and present in felids from nearby watersheds.why some toxoplasma gondii-infected southern sea otters (enhydra lutris nereis) develop fatal toxoplasmosis while others have incidental or mild chronic infections has long puzzled the scientific community. we assessed robust datasets on t. gondii molecular characterization in relation to detailed necropsy and histopathology results to evaluate whether parasite genotype influences pathological outcomes in sea otters that stranded along the central california coast. genotypes isolated from sea ot ...201931431162
concentrations of organohalogens (pcbs, ddts, pbdes) in hunted and stranded northern sea otters (enhydra lutris kenyoni) in alaska from 1992 to 2010: links to pathology and feeding ecology.many organohalogen compounds (ohcs) are persistent organic pollutants (pops) found in appreciable concentrations in marine predators. while production of some pops has declined or ceased in recent decades, their capacity for global transport and bioaccumulation results in observations of unchanging or increasing concentrations in marine systems. sea otters (enhydra lutris) have been advocated as an environmental sentinel for contaminants due to their longevity, site fidelity and prey species tha ...201931326802
trophic control of cryptic coralline algal diversity.understanding how trophic dynamics drive variation in biodiversity is essential for predicting the outcomes of trophic downgrading across the world's ecosystems. however, assessing the biodiversity of morphologically cryptic lineages can be problematic, yet may be crucial to understanding ecological patterns. shifts in keystone predation that favor increases in herbivore abundance tend to have negative consequences for the biodiversity of primary producers. however, in nearshore ecosystems, cora ...201931285351
the evolution of gametic compatibility and compatibility groups in the sea urchin mesocentrotus franciscanus: an avenue for speciation in the sea.the generation of reproductive incompatibility between groups requires a rare genotype with low compatibility to increase in frequency. we tested the hypothesis that sexual conflict driven by the risk of polyspermy can generate compatibility groups in gamete recognition proteins (grps) in the sea urchin mesocentrotus franciscanus. we examined variation in the sperm (bindin) and egg (ebr1) grps, how this variation influences fertilization success and how allele frequencies shift in these grps ove ...201931125112
sex and occupation time influence niche space of a recovering keystone predator.predators exert strong effects on ecological communities, particularly when they re-occupy areas after decades of extirpation. within species, such effects can vary over time and by sex and cascade across trophic levels. we used a space-for-time substitution to make foraging observations of sea otters (enhydra lutris) across a gradient of reoccupation time (1-30 years), and nonmetric multidimensional scaling (nmds) analysis to ask whether (a) sea otter niche space varies as a function of occupat ...201930962895
wild sea otter mussel pounding leaves archaeological traces.wild sea otters (enhydra lutris) are the only marine mammals that habitually use stones while foraging, using them to break open hard-shelled foods like marine snails and bivalves. however, the physical effects of this behavior on local environments are unknown. we show that sea otters pounding mussels on tidally emergent rocks leave distinct material traces, which can be recognized using methods from archaeology. we observed sea otters pounding mussels at the bennett slough culverts site, calif ...201930872658
experiments reveal limited top-down control of key herbivores in southern california kelp forests.predator responses to gradients in prey density have important implications for population regulation and are a potential structuring force for subtidal marine communities, particularly on rocky reefs where herbivorous sea urchins can drive community state shifts. on rocky reefs in southern california where predatory sea otters have been extirpated, top-down control of sea urchins by alternative predators has been hypothesized but rarely tested experimentally. in laboratory feeding assays, preda ...201930648729
mycoplasma enhydrae sp. nov. isolated from southern sea otters (enhydra lutris nereis).five mycoplasma strains have been isolated from the oropharynx of southern sea otters (enhydra lutris nereis) from the central california coast, usa. these strains were phenotypically and genetically characterized and compared to other established mycoplasma species. all five strains hydrolysed arginine but not urea, but did not produce acid from glucose, and all were isolated and propagated under anaerobic and aerobic atmospheric conditions at +35-37 ˚c using either sp4 or pplo medium supplemen ...201930543510
viral emergence in marine mammals in the north pacific may be linked to arctic sea ice reduction.climate change-driven alterations in arctic environments can influence habitat availability, species distributions and interactions, and the breeding, foraging, and health of marine mammals. phocine distemper virus (pdv), which has caused extensive mortality in atlantic seals, was confirmed in sea otters in the north pacific ocean in 2004, raising the question of whether reductions in sea ice could increase contact between arctic and sub-arctic marine mammals and lead to viral transmission acros ...201931700005
non-trophic impacts from white sharks complicate population recovery for sea otters.complex interactions between protected populations may challenge the recovery of whole ecosystems. in california, white sharks (carcharodon carcharias) mistargeting southern sea otters (enhydra lutris nereis) are an emergent impact to sea otter recovery, inhibiting the broader ecosystem restoration sea otters might provide. here, we integrate and analyze tracking and stranding data to compare the phenology of interactions between white sharks and their targeted prey (elephant seals, mirounga ang ...201931236228
collagen fingerprinting and the earliest marine mammal hunting in north america.the submersion of late pleistocene shorelines and poor organic preservation at many early archaeological sites obscure the earliest effects of humans on coastal resources in the americas. we used collagen fingerprinting to identify bone fragments from middens at four california channel island sites that are among the oldest coastal sites in the americas (~12,500-8,500 cal bp). we document paleocoastal human predation of at least three marine mammal families/species, including northern elephant s ...201829968785
are the ghosts of nature's past haunting ecology today?humans have decimated populations of large-bodied consumers and their functions in most of the world's ecosystems. it is less clear how human activities have affected the diversity of habitats these consumers occupy. rebounding populations of some predators after conservation provides an opportunity to begin to investigate this question. recent research shows that following long-term protection, sea otters along the northeast pacific coast have expanded into estuarine marshes and seagrasses, and ...201829738721
comparative ecology of bartonella and brucella infections in wild carnivores.phylogenetic sister clades bartonella and brucella within the order rhizobiales present some common biological characteristics as well as evident differences in adaptations to their mammalian reservoirs. we reviewed published data on bartonella and brucella infections in wild carnivores to compare the ecology of these bacteria in relatively similar host environments. arthropod vectors are the main mechanism for bartonella species transmission between mammalian hosts. the role of arthropods in tr ...201830662899
eye optics in semiaquatic mammals for aerial and aquatic vision.based on anatomical measurements of refractive structures in the eye, the positions of focused images were computed for several groups of semiaquatic mammals: rodents, a nonpinniped semiaquatic carnivore (the sea otter), and pinniped carnivores (seals, sea lions, and the walrus). in semiaquatic rodents, eye optics enable emmetropia in the air but cause substantial hypermetropia in the water. in semiaquatic carnivores, there are several mechanisms for amphibious vision that focus images on the re ...201830799395
measures of effective population size in sea otters reveal special considerations for wide-ranging species.conservation genetic techniques and considerations of the evolutionary potential of a species are increasingly being applied to species conservation. for example, effective population size (ne) estimates are useful for determining the conservation status of species, yet accurate estimates of current ne remain difficult to obtain. the effective population size can contribute to setting federal delisting criteria, as was done for the southern sea otter (enhydra lutris nereis). after being hunted t ...201830459829
from the predictable to the unexpected: kelp forest and benthic invertebrate community dynamics following decades of sea otter expansion.the recovery of predators has the potential to restore ecosystems and fundamentally alter the services they provide. one iconic example of this is keystone predation by sea otters in the northeast pacific. here, we combine spatial time series of sea otter abundance, canopy kelp area, and benthic invertebrate abundance from washington state, usa, to examine the shifting consequences of sea otter reintroduction for kelp and kelp forest communities. we leverage the spatial variation in sea otter re ...201830311056
lactation and resource limitation affect stress responses, thyroid hormones, immune function, and antioxidant capacity of sea otters (enhydra lutris).lactation is the most energetically demanding stage of reproduction in female mammals. increased energetic allocation toward current reproduction may result in fitness costs, although the mechanisms underlying these trade-offs are not well understood. trade-offs during lactation may include reduced energetic allocation to cellular maintenance, immune response, and survival and may be influenced by resource limitation. as the smallest marine mammal, sea otters (enhydra lutris) have the highest ma ...201830250713
complete genome sequence of a novel sea otterpox virus.members of the poxviridae family are large, double-stranded dna viruses that replicate in the cytoplasm of their host cells. the subfamily chordopoxvirinae contains viruses that infect a wide range of vertebrates including marine mammals within the balaenidae, delphinidae, mustelidae, odobenidae, otariidae, phocidae, and phocoenidae families. recently, a novel poxvirus was found in a northern sea otter pup (enhydra lutris kenyoni) that stranded in alaska in 2009. the phylogenetic relationships o ...201830225673
active touch in sea otters: in-air and underwater texture discrimination thresholds and behavioral strategies for paws and vibrissae.sea otters (enhydra lutris) are marine predators that forage on a wide array of cryptic, benthic invertebrates. observational studies and anatomical investigations of the sea otter somatosensory cortex suggest that touch is an important sense for detecting and capturing prey. sea otters have two well-developed tactile structures: front paws and facial vibrissae. in this study, we use a two-alternative forced choice paradigm to investigate tactile sensitivity of a sea otter subject's paws and vib ...201830224372
defining the risk landscape in the context of pathogen pollution: toxoplasma gondii in sea otters along the pacific rim.pathogens entering the marine environment as pollutants exhibit a spatial signature driven by their transport mechanisms. the sea otter (enhydra lutris), a marine animal which lives much of its life within sight of land, presents a unique opportunity to understand land-sea pathogen transmission. using a dataset on toxoplasma gondii prevalence across sea otter range from alaska to california, we found that the dominant drivers of infection risk vary depending upon the spatial scale of analysis. a ...201830109036
sudden collapse of a mesopredator reveals its complementary role in mediating rocky reef regime shifts.while changes in the abundance of keystone predators can have cascading effects resulting in regime shifts, the role of mesopredators in these processes remains underexplored. we conducted annual surveys of rocky reef communities that varied in the recovery of a keystone predator (sea otter, enhydra lutris) and the mass mortality of a mesopredator (sunflower sea star, pycnopodia helianthoides) due to an infectious wasting disease. by fitting a population model to empirical data, we show that sea ...201830051864
an update on toxoplasma gondii infections in northern sea otters (enhydra lutris kenyoni) from washington state, usa.toxoplasmosis in marine mammals is epidemiologically and clinically important. toxoplasma gondii antibodies (by modified agglutination test, cut-off ≥1:25) were detected in serum of 65 of 70 (92.9%) northern sea otters (enhydra lutris kenyoni) from washington state, usa. brains and/or muscles of 44 sea otters were bioassayed in mice (inf-γ knock-out [ko], swiss webster outbred [sw]) and viable t. gondii was isolated from 22 of 44 (50%); t. gondii strains were lethal to ko mice but not sw mice. t ...201829941160
bioerosion by pit-forming, temperate-reef sea urchins: history, rates and broader implications.sea urchins are dominant members of rocky temperate reefs around the world. they often occur in cavities within the rock, and fit so tightly, it is natural to assume they sculpted these "pits." however, there are no experimental data demonstrating they bore pits. if they do, what are the rates and consequences of bioerosion to nearshore systems? we sampled purple sea urchins, strongylocentrotus purpuratus, from sites with four rock types, three sedimentary (two sandstones and one mudstone) and o ...201829466357
monitoring dynamic spatio-temporal ecological processes optimally.population dynamics vary in space and time. survey designs that ignore these dynamics may be inefficient and fail to capture essential spatio-temporal variability of a process. alternatively, dynamic survey designs explicitly incorporate knowledge of ecological processes, the associated uncertainty in those processes, and can be optimized with respect to monitoring objectives. we describe a cohesive framework for monitoring a spreading population that explicitly links animal movement models with ...201829369341
the dimensionality of individual niche variation.the inherently multidimensional nature of the niche has not yet been integrated into the investigation of individual niche specialization within populations. we propose a framework for modeling the between- and within-individual components of the population niche as a set of variance-covariance matrices, which can be visualized with ellipses or ellipsoids. these niche components can be inferred using multiple response mixed models, and can incorporate diverse types of data, including diet compos ...201829282710
size, growth, and density data for shallow-water sea urchins from mexico to the aleutian islands, alaska, 1956-2016.size, growth, and density have been studied for north american pacific coast sea urchins strongylocentrotus purpuratus, s. droebachiensis, s. polyacanthus, mesocentrotus (strongylocentrotus) franciscanus, lytechinus pictus, centrostephanus coronatus, and arbacia stellata by various workers at diverse sites and for varying lengths of time from 1956 to present. numerous peer-reviewed publications have used some of these data but some data have appeared only in graduate theses or the gray literatur ...201829281144
mortality trends in northern sea otters ( enhydra lutris kenyoni) collected from the coasts of washington and oregon, usa (2002-15).during 2002-15 we examined the causes of mortality in a population of northern sea otters ( enhydra lutris kenyoni). beachcast sea otters were collected primarily from the us coast of washington. although there are no permanent sea otter residents in oregon, several beachcast otters were collected from the oregon coast. infectious diseases were the primary cause of death (56%) for otters we examined. sarcocystosis was the leading infectious cause of death (54%) and was observed throughout the st ...201829261446
molecular characterization and prevalence of halarachne halichoeri in threatened southern sea otters (enhydra lutris nereis).parasitism, particularly in concert with other sublethal stressors, may play an important, yet underappreciated role in morbidity and mortality of threatened species. during necropsy of southern sea otters (enhydra lutra nereis) from california submitted to the marine wildlife veterinary care and research center's sea otter necropsy program between 1999 and 2017, pathologists occasionally observed nasopulmonary mites infesting the respiratory tracts. infestation was sometimes accompanied by lesi ...201830370218
streptococcus phocae in marine mammals of northeastern pacific and arctic canada: a retrospective analysis of 85 postmortem investigations.:  streptococcus phocae is a pathogen of marine mammals, although its pathogenicity remains poorly understood. recovery of this bacterium from asymptomatic carriers suggests that it is an opportunistic pathogen. we investigated the role of s. phocae in naturally occurring disease and its significance as a pathogen based on postmortem investigations. between 2007 and 2012, 1,696 whole carcasses, tissue samples, or both were submitted from the northeastern pacific and arctic canada for diagnostic ...201828982020
optimal marine mammal welfare under human care: current efforts and future directions.marine mammals include cetaceans, pinnipeds, sirenians, sea otters and polar bears, many of which are charismatic and popular species commonly kept under human care in zoos and aquaria. however, in comparison with their fully terrestrial counterparts their welfare has been less intensively studied, and their partial or full reliance on the aquatic environment leads to unique welfare challenges. in this paper we attempt to collate and review the research undertaken thus far on marine mammal welfa ...201828927965
ecosystem features determine seagrass community response to sea otter foraging.comparing sea otter recovery in california (ca) and british columbia (bc) reveals key ecosystem properties that shape top-down effects in seagrass communities. we review potential ecosystem drivers of sea otter foraging in ca and bc seagrass beds, including the role of coastline complexity and environmental stress on sea otter effects. in bc, we find greater species richness across seagrass trophic assemblages. furthermore, cancer spp. crabs, an important link in the seagrass trophic cascade obs ...201829221592
toxoplasma gondii infection in wild mustelids and cats across an urban-rural gradient.the increase in human population and domestic pets, such as cats, are generating important consequences in terms of habitat loss and pathogen pollution of coastal ecosystems with potential to generate negative impacts in marine biodiversity. toxoplasma gondii is the etiological agent of zoonotic disease toxoplasmosis, and is associated with cat abundance and anthropogenic disturbance. the presence of t. gondii oocysts in the ocean has negatively affected the health status of the threatened south ...201829924844
selective regimes and functional anatomy in the mustelid forelimb: diversification toward specializations for climbing, digging, and swimming.anatomical traits associated with locomotion often exhibit specializations for ecological niche, suggesting that locomotor specializations may constitute selective regimes acting on limb skeletal traits. to test this, i sampled 42 species of mustelidae, encompassing climbing, digging, and swimming specialists, and determined whether trait variation reflects locomotor specialization by performing a principal components analysis on 14 forelimb traits. in addition to brownian motion models, three o ...201729152182
feeding capability in the extinct giant siamogale melilutra and comparative mandibular biomechanics of living lutrinae.at 50 kg in estimated weight, the extinct siamogale melilutra is larger than all living otters, and ranks among the largest fossil otters. the biomechanical capability of s. melilutra jaws as related to their large size is unknown but crucial to reconstructing the species' potentially unique ecological niche. here we compare the mandibular biomechanics of s. melilutra using engineering-based performance measures against ten extant otter biomechanical models. despite a wide range of feeding prefe ...201729123190
durophagous biting in sea otters (enhydra lutris) differs kinematically from raptorial biting of other marine mammals.sea otters represent an interesting model for studies of mammalian feeding evolution. although they are marine mammals, sea otters returned to the sea relatively recently and feed at the surface. therefore, they represent a transitional stage of aquatic adaptation. currently no feeding performance studies of sea otters have been conducted. the main objective of this study was to characterize the feeding kinematic profile in sea otters. it was hypothesized that sea otters would exhibit a terrestr ...201729074703
serendipity in a salt marsh: detecting frequent sea otter haul outs in a marsh ecosystem. 201728960281
the genome of the northern sea otter (enhydra lutris kenyoni).the northern sea otter inhabits coastal waters of the northern pacific ocean and is the largest member of the mustelidae family. dna sequencing methods that utilize microfluidic partitioned and non-partitioned library construction were used to establish the sea otter genome. the final assembly provided 2.426 gbp of highly contiguous assembled genomic sequences with a scaffold n50 length of over 38 mbp. we generated transcriptome data derived from a lymphoma to aid in the determination of functio ...201729232880
oil spills and marine mammals in british columbia, canada: development and application of a risk-based conceptual framework.marine mammals are inherently vulnerable to oil spills. we developed a conceptual framework to evaluate the impacts of potential oil exposure on marine mammals and applied it to 21 species inhabiting coastal british columbia (bc), canada. oil spill vulnerability was determined by examining both the likelihood of species-specific (individual) oil exposure and the consequent likelihood of population-level effects. oil exposure pathways, ecology, and physiological characteristics were first used to ...201728695252
explicit not implicit preferences predict conservation intentions for endangered species and biomes.conservation of biodiversity is determined in part by human preferences. preferences relevant to conservation have been examined largely via explicit measures (e.g., a self-reported degree of liking), with implicit measures (e.g., preconscious, automatic evaluations) receiving relatively less attention. this is the case despite psychological evidence from other contexts that implicit preferences are more informative of behavior. thus, the type of measure that predicts conservation intentions for ...201728135298
mitogenomes and relatedness do not predict frequency of tool-use by sea otters.many ecological aspects of tool-use in sea otters are similar to those in indo-pacific bottlenose dolphins. within an area, most tool-using dolphins share a single mitochondrial haplotype and are more related to each other than to the population as a whole. we asked whether sea otters in california showed similar genetic patterns by sequencing mitogenomes of 43 otters and genotyping 154 otters at 38 microsatellite loci. there were six variable sites in the mitogenome that yielded three haplotype ...201728330975
brucella infection in asian sea otters (enhydra lutris lutris) on bering island, russia.infection with brucella spp., long known as a cause of abortion, infertility, and reproductive loss in domestic livestock, has increasingly been documented in marine mammals over the past two decades. we report molecular evidence of brucella infection in asian sea otters (enhydra lutris lutris). brucella dna was detected in 3 of 78 (4%) rectal swab samples collected between 2004 and 2006 on bering island, russia. these 78 animals had previously been documented to have a brucella seroprevalence o ...201728715292
other helicobacters, gastric and gut microbiota.the current article is a review of the most important and relevant literature published in 2016 and early 2017 on non-helicobacter pylori helicobacter infections in humans and animals, as well as interactions between h. pylori and the microbiota of the stomach and other organs. some putative new helicobacter species were identified in sea otters, wild boars, dogs, and mice. many cases of helicobacter fennelliae and helicobacter cinaedi infection have been reported in humans, mostly in immunocomp ...201728891140
discovery of the fossil otter enhydritherium terraenovae (carnivora, mammalia) in mexico reconciles a palaeozoogeographic mystery.the north american fossil otter enhydritherium terraenovae is thought to be partially convergent in ecological niche with the living sea otter enhydra lutris, both having low-crowned crushing teeth and a close association with marine environments. fossil records of enhydritherium are found in mostly marginal marine deposits in california and florida; despite presence of very rich records of fossil terrestrial mammals in contemporaneous localities inland, no enhydritherium fossils are hitherto kn ...201728615353
sea otters, social justice, and ecosystem-service perceptions in clayoquot sound, canada.we sought to take a first step toward better integration of social concerns into empirical ecosystem service (es) work. we did this by adapting cognitive anthropological techniques to study the clayoquot sound social-ecological system on the pacific coast of canada's vancouver island. we used freelisting and ranking exercises to elicit how locals perceive ess and to determine locals' preferred food species. we analyzed these data with the freelist-analysis software package anthropac. we consider ...201727406400
first report of an adult tapeworm (cestoda: diphyllobothriidea) in a southern sea otter (enhydra lutris nereis).we present a novel case of an intestinal cestode infection in a southern sea otter (enhydra lutris nereis). the cestode species diplogonoporus tetrapterus was confirmed genetically. stable isotope analysis of whiskers collected from the sea otter did not confirm the consumption of fish as the route of exposure.201728640666
serologic detection of subtype-specific antibodies to influenza a viruses in southern sea otters (enhydra lutris nereis).there are approximately 3,000 southern sea otters (enhydra lutris nereis) in the nearshore environment along the california coast, and the species is classified as threatened under the endangered species act. we tested sera from 661 necropsied southern sea otters sampled from 1997 to 2015 to determine overall exposure to influenza a viruses (iavs) and to identify subtype-specific antibody responses. using an enzyme-linked immunosorbent assay (elisa), antibodies to iav nucleoproteins were detecte ...201728513329
isolation and characterization of a novel marine brucella from a southern sea otter (enhydra lutris nereis), california, usa.we characterize brucella infection in a wild southern sea otter ( enhydra lutris nereis) with osteolytic lesions similar to those reported in other marine mammals and humans. this otter stranded twice along the central california coast, us over a 1-yr period and was handled extensively at two wildlife rehabilitation facilities, undergoing multiple surgeries and months of postsurgical care. ultimately the otter was euthanized due to severe, progressive neurologic disease. necropsy and postmortem ...201728151078
endemic infection of stranded southern sea otters (enhydra lutris nereis) with novel parvovirus, polyomavirus, and adenovirus.over the past century, the southern sea otter (sso; enhydra lutris nereis) population has been slowly recovering from near extinction due to overharvest. the sso is a threatened species under federal law and a fully protected species under california law. through a multiagency collaborative program, stranded animals are rehabilitated and released, while deceased animals are necropsied and tissues are cryopreserved to facilitate scientific study. here, we processed archival tissues to enrich part ...201728192039
novel urease-negative helicobacter sp. 'h. enhydrae sp. nov.' isolated from inflamed gastric tissue of southern sea otters.a total of 31 sea otters enhydra lutris nereis found dead or moribund (and then euthanized) were necropsied in california, usa. stomach biopsies were collected and transected with equal portions frozen or placed in formalin and analyzed histologically and screened for helicobacter spp. in gastric tissue. helicobacter spp. were isolated from 9 sea otters (29%); 58% (18 of 31) animals were positive for helicobacter by pcr. the helicobacter sp. was catalase- and oxidase-positive and urease-negative ...201728177288
the flehmen response and pseudosuckling in a captive, juvenile southern sea otter (enhydra lutris nereis).a juvenile, female sea otter (enhydra lutris nereis) was observed in 43 instances of the flehmen response over 19 days from may through july of 2015 at the oregon zoo. in all flehmen grimace observations, the juvenile sea otter engaged in nibbling, nosing, or licking the peri-mammary or anogenital areas of a non-lactating, geriatric female sea otter. the flehmen behavior observed was consisted with the sequences of behavior documented in other mammals, lifting the head, elevating the nose to the ...201728111787
an integrated data model to estimate spatiotemporal occupancy, abundance, and colonization dynamics.ecological invasions and colonizations occur dynamically through space and time. estimating the distribution and abundance of colonizing species is critical for efficient management or conservation. we describe a statistical framework for simultaneously estimating spatiotemporal occupancy and abundance dynamics of a colonizing species. our method accounts for several issues that are common when modeling spatiotemporal ecological data including multiple levels of detection probability, multiple d ...201728052322
predicting animal home-range structure and transitions using a multistate ornstein-uhlenbeck biased random walk.the home-range concept is central in animal ecology and behavior, and numerous mechanistic models have been developed to understand home range formation and maintenance. these mechanistic models usually assume a single, contiguous home range. here we describe and implement a simple home-range model that can accommodate multiple home-range centers, form complex shapes, allow discontinuities in use patterns, and infer how external and internal variables affect movement and use patterns. the model ...201727893946
morphological analysis of long bones in semi-aquatic mustelids and their terrestrial relatives.the locomotor environment and behavior of quadrupedal mammals exert functional constraints on their limbs. therefore long bone shapes are thought to reflect at least partially the species' locomotor ecology. semi-aquatic species move through two media with distinct density and viscosity and their locomotor apparatus should therefore reflect a trade-off between the divergent functional constraints it faces. adaptation to a semi-aquatic lifestyle occurred independently in otters (lutrinae) and min ...201627794537
ontogenetic scaling of theoretical bite force in southern sea otters (enhydra lutris nereis).sexual dimorphism attributed to niche divergence is often linked to differentiation between the sexes in both dietary resources and characters related to feeding and resource procurement. although recent studies have indicated that southern sea otters (enhydra lutris nereis) exhibit differences in dietary preferences as well as sexual dimorphism in skull size and shape, whether these intersexual differences translate to differentiation in feeding performances between the sexes remains to be inve ...201627617357
comparison of human and southern sea otter (enhydra lutris nereis) health risks for infection with protozoa in nearshore waters.cryptosporidium and giardia spp. are waterborne, fecally-transmitted pathogens that cause economic loss due to gastroenteritis and beach closures. we applied quantitative microbial risk assessment (qmra) to determine the health risks for humans and sea otters due to waterborne exposure of cryptosporidium and giardia spp. when swimming in three types of surface waters: river, stormwater and wastewater effluent during the wet and dry seasons in the central coast of california. this is the first ap ...201627525585
the high cost of reproduction in sea otters necessitates unique physiological adaptations.superimposed on inherently high basal metabolic demands, the additional energetic requirements of reproduction can push female sea otters beyond physiological limits. indeed, the resulting energy imbalance contributes to disproportionately high rates of mortality at the end of lactation in this species. to examine and quantify metabolic changes associated with reproduction, we measured the resting metabolic rate (rmr) of a female sea otter across gestation, lactation and non-reproductive periods ...201627489214
pharmacokinetic indices for cefovecin after single-dose administration to adult sea otters (enhydra lutris).seven sea otters received a single subcutaneous dose of cefovecin at 8 mg/kg body weight. plasma samples were collected at predetermined time points and assayed for total cefovecin concentrations using ultra-performance liquid chromatography and tandem mass spectrometry. the mean (±sd) noncompartmental pharmacokinetic indices were as follows: cmax (obs) 70.6 ± 14.6 μg/ml, tmax (obs) 2.9 ± 1.5 h, elimination rate constant (kel ) 0.017 ± 0.002/h, elimination half-life (t1/2kel) 41.6 ± 4.7 h, area ...201627212054
antidog igg secondary antibody successfully detects igg in a variety of aquatic mammals.serological tests play an important role in the detection of wildlife diseases. however, while there are many commercial assays and reagents available for domestic species, there is a need to develop efficient serological assays for wildlife. in recent years, marine mammals have represented a wildlife group with emerging infectious diseases, such as influenza, brucellosis, and leptospirosis. however, with the exception of disease-agent-specific assays or functional assays, few reports describe t ...201628080908
auditory sensitivity and masking profiles for the sea otter (enhydra lutris).sea otters are threatened marine mammals that may be negatively impacted by human-generated coastal noise, yet information about sound reception in this species is surprisingly scarce. we investigated amphibious hearing in sea otters by obtaining the first measurements of absolute sensitivity and critical masking ratios. auditory thresholds were measured in air and underwater from 0.125 to 40 khz. critical ratios derived from aerial masked thresholds from 0.25 to 22.6 khz were also obtained. the ...201626610978
detection and characterization of diverse coccidian protozoa shed by california sea lions.tissue-cyst forming coccidia in the family sarcocystidae are etiologic agents of protozoal encephalitis in marine mammals including the federally listed southern sea otter (enhydra lutris). california sea lions (zalophus californianus), whose coastal habitat overlaps with sea otters, are definitive hosts for coccidian protozoa provisionally named coccidia a, b and c. while coccidia a and b have unknown clinical effects on aquatic wildlife hosts, coccidia c is associated with severe protozoal dis ...201627141438
california mussels (mytilus californianus) as sentinels for marine contamination with sarcocystis neurona.sarcocystis neurona is a terrestrial parasite that can cause fatal encephalitis in the endangered southern sea otter (enhydra lutris nereis). to date, neither risk factors associated with marine contamination nor the route of s. neurona infection to marine mammals has been described. this study evaluated coastal s. neurona contamination using california mussels (mytilus californianus) as sentinels for pathogen pollution. a field investigation was designed to test the hypotheses that (1) mussels ...201627003262
dual congenital transmission of toxoplasma gondii and sarcocystis neurona in a late-term aborted pup from a chronically infected southern sea otter (enhydra lutris nereis).toxoplasma gondii and sarcocystis neurona are protozoan parasites with terrestrial definitive hosts, and both pathogens can cause fatal disease in a wide range of marine animals. close monitoring of threatened southern sea otters (enhydra lutris nereis) in california allowed for the diagnosis of dual transplacental transmission of t. gondii and s. neurona in a wild female otter that was chronically infected with both parasites. congenital infection resulted in late-term abortion due to dissemina ...201626494610
prevalence, pathology, and risk factors associated with streptococcus phocae infection in southern sea otters (enhydra lutris nereis), 2004-10.recent studies have implicated beta-hemolytic streptococci as opportunistic pathogens of marine mammals, including southern sea otters (enhydra lutris nereis), but little is known about their prevalence or pathophysiology. herein, we focus on risk factors for sea otter infection by a single beta-hemolytic streptococcal species, streptococcus phocae. streptococcus phocae was first identified as a marine mammal pathogen in 1994, and the first report in southern sea otters was in 2009. its broad ho ...201626555115
concentration and retention of toxoplasma gondii surrogates from seawater by red abalone (haliotis rufescens).small marine snails and abalone have been identified as high- and low-risk prey items, respectively, for exposure of threatened southern sea otters to toxoplasma gondii, a zoonotic parasite that can cause fatal encephalitis in animals and humans. while recent work has characterized snails as paratenic hosts for t. gondii, the ability of abalone to vector the parasite has not been evaluated. to further elucidate why abalone predation may be protective against t. gondii exposure, this study aimed ...201627573192
prevalence of algal toxins in alaskan marine mammals foraging in a changing arctic and subarctic environment.current climate trends resulting in rapid declines in sea ice and increasing water temperatures are likely to expand the northern geographic range and duration of favorable conditions for harmful algal blooms (habs), making algal toxins a growing concern in alaskan marine food webs. two of the most common hab toxins along the west coast of north america are the neurotoxins domoic acid (da) and saxitoxin (stx). over the last 20 years, da toxicosis has caused significant illness and mortality in m ...201628073526
evolutionary relationships between digeneans of the family brachycladiidae odhner, 1905 and their marine mammal hosts: a cophylogenetic study.cophylogenetic studies examine the congruence between host and parasite phylogenies. there are few studies that quantify the relative contribution of coevolutionary events, i.e. duplication, loss, failure-to-diverge, host-switching and spreading in trophically-transmitted parasites at the marine realm. we addressed this issue in the brachycladiidae, a cosmopolitan digenean family specific to marine mammals. we used, for the first time, distance-based and event-based methods to explicitly test th ...201626721312
organization of the retinal ganglion layer and retinal resolution in the sea otter (enhydra lutris). 201610833638
trophic cascades on the edge: fostering seagrass resilience via a novel pathway.despite widespread degradation, some coastal ecosystems display remarkable resilience. for seagrasses, a century-old paradigm has implicated macroalgal blooms stimulated by anthropogenic nutrient, loading as a primary driver of seagrass decline, yet relatively little attention has been given to drivers of seagrass resilience. in elkhorn slough, ca, an estuarine system characterized by extreme anthropogenic nutrient loading and macroalgal (ulva spp.) blooms, seagrass (zostera marina) beds have re ...201627167224
sea otters, kelp forests, and the extinction of steller's sea cow.the late pleistocene extinction of so many large-bodied vertebrates has been variously attributed to two general causes: rapid climate change and the effects of humans as they spread from the old world to previously uninhabited continents and islands. many large-bodied vertebrates, especially large apex predators, maintain their associated ecosystems through top-down forcing processes, especially trophic cascades, and megaherbivores also exert an array of strong indirect effects on their communi ...201626504217
the high cost of motherhood: end-lactation syndrome in southern sea otters (enhydra lutris nereis) on the central california coast, usa.sea otters ( enhydra lutris ) have exceptionally high energetic requirements, which nearly double during lactation and pup care. thus, females are extremely vulnerable to caloric insufficiency. despite a number of compensatory strategies, the metabolic challenge of reproduction culminates in numerous maternal deaths annually. massive depletion of energy reserves results in a case presentation that we define as end-lactation syndrome (els), characterized by moderate to severe emaciation not attri ...201626967137
accounting for size-specific predation improves our ability to predict the strength of a trophic cascade.predation can influence the magnitude of herbivory that grazers exert on primary producers by altering both grazer abundance and their per capita consumption rates via changes in behavior, density-dependent effects, and size. therefore, models based solely on changes in abundance may miss key components of grazing pressure. we estimated shifts in grazing pressure associated with changes in the abundance and per capita consumption rates of sea urchins triggered by size-selective predation by sea ...201626941943
osteosarcoma of the maxilla with concurrent osteoma in a southern sea otter (enhydra lutris nereis).southern sea otters (enhydra lutris nereis) are threatened marine mammals that belong to the family mustelidae and are native to the coast of central california. neoplasia is reported infrequently in sea otters. an adult female free-ranging southern sea otter was found alive at pebble beach, monterey county, california, on january 1st, 1994 and died soon after capture. the carcass was submitted to the us geological survey - national wildlife health center for necropsy examination. grossly, a mas ...201622520807
of mussels and men.some species are more equal than others. robert t. paine (american ecologist, 1933-2016) discovered that if you remove starfish - what he called a "keystone species" - from a tide pool, the complex ecosystem collapses. without the predator starfish, mussels choke out other animals and plants. this phenomenon is general. sea otters eat the sea urchins that eat the kelp that provides food and habitat for other species. on the vast serengeti plains, wildebeest "mow" the grass, protecting habitat fo ...201627585022
permissible home range estimation (phre) in restricted habitats: a new algorithm and an evaluation for sea otters.parametric and nonparametric kernel methods dominate studies of animal home ranges and space use. most existing methods are unable to incorporate information about the underlying physical environment, leading to poor performance in excluding areas that are not used. using radio-telemetry data from sea otters, we developed and evaluated a new algorithm for estimating home ranges (hereafter permissible home range estimation, or "phre") that reflects habitat suitability. we began by transforming si ...201627003710
a unique feeding strategy of the extinct marine mammal kolponomos: convergence on sabretooths and sea otters.mammalian molluscivores feed mainly by shell-crushing or suction-feeding. the extinct marine arctoid, kolponomos, has been interpreted as an otter-like shell-crusher based on similar dentitions. however, neither the masticatory biomechanics of the shell-crushing adaptation nor the way kolponomos may have captured hard-shelled prey have been tested. based on mandibular symphyseal morphology shared by kolponomos and sabre-toothed carnivores, we hypothesize a sabretooth-like mechanism for kolponomo ...201626936242
novel finding of widespread occurrence and accumulation of bisphenol a diglycidyl ethers (badges) and novolac glycidyl ethers (noges) in marine mammals from the united states coastal waters.bisphenol a diglycidyl ether (badge)- and bisphenol f diglycidyl ether (bfdge)-based epoxy resins have a broad range of applications, including serving as inner coatings of food and beverage cans and as protective coatings in marine construction. prior to this study, no studies had examined the occurrence and bioaccumulation of badges or bfdges in aquatic organisms. in this study, badge, bfdge, and nine of their derivatives were determined in 121 tissue (liver, kidney, blubber, and brain) sample ...201626800265
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