After nearly a century of recovery from overhunting, sea otter populations are in abrupt decline over large areas of western Alaska. Increased killer whale predation is the likely cause of these ...declines. Elevated sea urchin density and the consequent deforestation of kelp beds in the nearshore community demonstrate that the otter's keystone role has been reduced or eliminated. This chain of interactions was probably initiated by anthropogenic changes in the offshore oceanic ecosystem.
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Sea otters (Enhydra lutris) have the highest mass-specific metabolic rate of any marine mammal, which is superimposed on the inherently high costs of reproduction and lactation in adult females. ...These combined energetic demands have been implicated in the poor body condition and increased mortality of female sea otters nearing the end of lactation along the central California coast. However, the cost of lactation is unknown and currently cannot be directly measured for this marine species in the wild. Here, we quantified the energetic demands of immature sea otters across five developmental stages as a means of assessing the underlying energetic challenges associated with pup rearing that may contribute to poor maternal condition. Activity-specific metabolic rates, daily activity budgets and field metabolic rates (FMR) were determined for each developmental stage. Mean FMR of pre-molt pups was 2.29 ± 0.81 MJ day(-1) and increased to 6.16 ± 2.46 and 7.41 ± 3.17 MJ day(-1) in post-molt pups and dependent immature animals, respectively. Consequently, daily energy demands of adult females increase 17% by 3 weeks postpartum and continue increasing to 96% above pre-pregnancy levels by the average age of weaning. Our results suggest that the energetics of pup rearing superimposed on small body size, marine living and limited on-board energetic reserves conspire to make female sea otters exceptionally vulnerable to energetic shortfalls. By controlling individual fitness, maternal behavior and pup provisioning strategies, this underlying metabolic challenge appears to be a major factor influencing current population trends in southern sea otters (Enhydra lutris nereis).
1. Longitudinal records of prey selection by 10 adult female sea otters on the Monterey Peninsula, California, from 1983 to 1990 demonstrate extreme inter-individual variation in diet. Variation in ...prey availability cannot explain these differences as the data were obtained from a common spatial-temporal area. 2. Individual dietary patterns persisted throughout our study, thus indicating that they are life-long characteristics. 3. Individual dietary patterns in sea otters appear to be transmitted along matrilines, probably by way of learning during the period of mother-young association. 4. Efficient utilization of different prey types probably requires radically different sensory/motor skills, each of which is difficult to acquire and all of which may exceed the learning and performance capacities of any single individual. This would explain the absence of generalists and inertia against switching, but not the existence of alternative specialists. 5. Such individual variation might arise in a constant environment from frequency-dependent effects, whereby the relative benefit of a given prey specialization depends on the number of other individuals utilizing that prey. Additionally, many of the sea otter's prey fluctuate substantially in abundance through time. This temporal variation, in conjunction with matrilineal transmission of foraging skills, may act to mediate the temporal dynamics of prey specializations. 6. Regardless of the exact cause, such extreme individual variation in diet has broad ramifications for population and community ecology. 7. The published literature indicates that similar patterns occur in many other species.
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Protective legislation and management have led to an increase in California’s sea otter Enhydra lutris nereis population. While sea otter recovery has been linked to ecosystem benefits, sea otter ...predation may negatively affect commercially valuable species. Understanding the potential influence of sea otters is of particular importance as their range expands into estuaries that function as nurseries for commercially valuable species like Dungeness crab Metacarcinus magister. We consider how sea otter predation has affected the abundance and size of juvenile Dungeness crab in Elkhorn Slough, California, USA, and analyzed cancrid crab abundance and size across 4 California estuaries with and without sea otters to understand how biotic and abiotic factors contribute to observed variation in crab size and abundance. We compared trends in southern sea otters relative to Dungeness crab landings in California to assess whether increasing sea otter abundance have negatively impacted landings. In Elkhorn Slough, juvenile Dungeness crab abundance and size have declined since 2012, coinciding with sea otter population growth. However, the impact of sea otters on juvenile Dungeness crab size was habitat-specific and only significant in unvegetated habitat. Across estuaries, we found that cancrid crab abundance and size were negatively associated with sea otter presence. While abiotic factors varied among estuaries, these factors explained little of the observed variation in crab abundance or size. Although we found evidence that sea otters can have localized effects on cancrid crab populations within estuaries, we found no evidence that southern sea otters, at recent population sizes, have negatively impacted Dungeness crab landings in California from 2000–2014.
Sea otters
Enhydra lutris
have been absent from Oregon, USA, following their extirpation over a century ago. Stakeholder groups and native tribes are advocating for reintroduction to restore historic ...populations. We investigated the potential for successful reintroduction by: (1) estimating expected equilibrium sea otter densities as a function of habitat variables to assess sea otter habitat in Oregon; and (2) spatially relating areas of high expected densities to human activities (e.g. fisheries, recreation, vessel activity, protected areas) to anticipate potential disturbance or fishery resource competition. We estimated that 4538 (1742-8976; 95% CI) sea otters could exist in Oregon, with higher expected abundance (N = 1551) and densities (
x̄
= 2.45 km
-2
) within the southern region. Most core habitat areas (97%), representing clusters of high expected densities, overlapped with some form of human activity. While commercial shipping and tow lanes overlapped little (1%) with core habitat areas, recreational activities (58%) and fisheries (76%) had a higher degree of overlap, posing higher disturbance risk. We anticipate higher resource competition potential with the commercial red sea urchin fishery (67% of harvest areas) than the commercial Dungeness crab fishery (9% of high-catch crabbing grounds). Our study presents the first published carrying capacity estimate for sea otters in Oregon and can provide population recovery targets, focus attention on ecological and socioeconomic considerations, and help to inform a recovery plan for a resident sea otter population. Our findings suggest current available habitat may be sufficient to support a sea otter population, but resource managers may need to further investigate and consider whether current human activities might conflict with reestablishment in Oregon, if plans for a reintroduction continue.
Background
Southern sea otters (Enhydra lutris nereis) rely on intact pelage for thermoregulation, and thus clinically significant demodicosis and associated alopecia can cause morbidity and death.
...Hypothesis/Objectives
This study aimed to describe lesions associated with follicular Demodex sp. infestation, estimate the prevalence and intensity of infestation, describe mite distribution across key anatomical regions, and assess mite presence or absence in relation to lesions and host risk factors.
Animals
Twenty necropsied, wild southern sea otters that stranded along the central California coast from 2005 to 2018.
Methods and materials
Grossly normal and abnormal integument from the head, perineum, genitals, mamillary papillae and limbs was assessed microscopically for mites and mite‐associated pathological findings.
Results
Intrafollicular mites were observed in the integument of 55% of otters and 20% had clinical demodicosis. Demodicosis was considered to be contributory to death or euthanasia in two cases. Although Demodex sp. mites often were observed microscopically in grossly normal skin, the presence of multiple densely‐packed intrafollicular mites generally was associated with pigmentary incontinence, ectatic follicles, lymphoplasmacytic perifolliculitis, and neutrophilic and lymphoplasmacytic, dermal inflammation. Other findings included epidermal hyperplasia, orthokeratotic hyperkeratosis of epidermis and follicular epithelium, concurrent pyoderma and cell necrosis. Perioral integument, especially of the chin, had the highest prevalence of mites and the highest mite density, suggesting facial contact as a means of mite transmission.
Conclusions and clinical importance
Our research confirmed demodectic mange as a contributor to morbidity and mortality in sea otters, with important implications for clinical care, rehabilitation and conservation.
Résumé
Contexte
La loutre de mer de Californie (Enhydra lutris nereis) utilise son pelage intact pour sa thermorégulation et ainsi, une démodécie cliniquement significative et l’alopécie associée peuvent causer une morbidité et la mort.
Hypothèses/Objectifs
Cette étude a pour but de décrire les lésions associées à une infestation folliculaire de Demodex sp., estimer la prévalence et l’intensité de l’infestation, décrire la distribution des acariens à l’aide de régions anatomiques clés et déterminer la présence ou l’absence d’acariens et les facteurs de risque des hôtes.
Sujets
Vingt loutres de mer de Californie sauvages ont été autopsiées après s’être échouées le long de la côte californienne de 2005 à 2018.
Matériels et méthodes
La peau macroscopiquement normale et anomale de la tête, du périnée, des zones génitales, des papilles mammaires et des membres a été évaluée microscopiquement pour les acariens et les lésions pathologiques liées aux acariens.
Résultats
Les acariens intrafolliculaires ont été observés dans la peau de 55% des loutres et 20% avaient une démodécie clinique. La démodécie a été considérée comme contribuant à la mort ou à l’euthanasie dans deux cas. Bien que les acariens Demodex sp. soient souvent observées dans la peau macroscopiquement normale, la présence multiple d’acariens intrafolliculaires regroupés en amas denses était généralement associée avec de l’incontinence pigmentaire, des follicules ectatiques, une périfolliculite lymphoplasmocytaire et une inflammation dermique neutrophilique et lymphoplasmocytaire. Les autres données regroupent une hyperplasie épidermique, une hyperkératose orthokératosique de l’épiderme et de l’épithélium folliculaire, une pyodermite concomitante et une nécrose cellulaire. La peau péri‐orale, en particulier le menton, avait la prévalence la plus élevée d’acariens et la densité en acarien la plus élevée suggérant un contact facial comme mode de transmission.
Conclusions et importance clinique
Nos recherches confirment que la démodécie participe à la morbidité et à la mortalité des loutres de mer avec implications importantes pour les soins de cliniques, de réhabilitation et de conservation.
RESUMEN
Introducción
las nutrias marinas del sur (Enhydra lutris nereis) dependen de un pelaje en buenas condiciones para la termorregulación y, por lo tanto, la demodicosis clínicamente significativa y la alopecia asociada pueden causar morbilidad y muerte.
Hipótesis/Objetivos
Este estudio tuvo como objetivo describir las lesiones asociadas con la infestación folicular por Demodex sp., estimar la prevalencia e intensidad de la infestación, describir la distribución de ácaros en regiones anatómicas clave y evaluar la presencia o ausencia de ácaros en relación con las lesiones y los factores de riesgo del huésped.
Animales
Veinte nutrias marinas salvajes del sur necropsiadas que quedaron varadas a lo largo de la costa central de California entre 2005 y 2018.
Métodos y materiales
Se evaluó microscópicamente el tegumento macroscópicamente normal y anormal de la cabeza, el perineo, los genitales, las papilas mamilares y las extremidades para detectar ácaros y hallazgos patológicos asociados a los ácaros.
Resultados
Se observaron ácaros intrafoliculares en el tegumento del 55% de las nutrias y el 20% presentó demodicosis clínica. Se consideró que la demodicosis contribuyó a la muerte o la eutanasia en dos casos. Aunque ácaros de Demodex sp. a menudo se observaron microscópicamente en piel macroscópica normal, la presencia de múltiples ácaros intrafoliculares densamente empaquetados generalmente se asoció con incontinencia pigmentaria, folículos ectásicos, perifoliculitis linfoplasmocítica e inflamación dérmica neutrofílica y linfoplasmacítica. Otros hallazgos incluyeron hiperplasia epidérmica, hiperqueratosis ortoqueratósica de epidermis y epitelio folicular, pioderma concurrente y necrosis celular. El tegumento perioral, especialmente del mentón, tuvo la mayor prevalencia de ácaros y la mayor densidad de ácaros, lo que sugiere el contacto facial como medio de transmisión de ácaros.
Conclusiones e importancia clínica
Nuestra investigación confirmó que la sarna demodécica contribuye a la morbilidad y mortalidad en las nutrias marinas, con importantes implicaciones para la atención clínica, la rehabilitación y la conservación.
Zusammenfassung
Hintergrund
Der Seeotter des Südpazifiks (Enhydra lutris nereis) benötigt zur Thermoregulierung zwingend ein intaktes Haarkleid und daher kann eine klinisch signifikante Demodikose und eine damit einhergehende Alopezie Erkrankung und Tod verursachen.
Hypothese/Ziele
Diese Studie zielte darauf ab, Veränderungen, die mit einer follikulären Demodex sp. Infektion einhergehen, zu beschreiben, die Prävalenz und die Intensität des Befalls abzuschätzen, die Milbenverteilung an den anatomischen Schlüsselregionen zu beschreiben, und die Milbenpräsenz oder deren Fehlen in Relation zu den Veränderungen und den Risikofaktoren des Wirtes zu beurteilen.
Tiere
Es wurden zwanzig wilde südliche Seeotter, die entlang der Küste Zentralkaliforniens zwischen 2005 und 2018 gestrandet waren, autopsiert.
Methoden und Materialien
Makroskopisch normale und abnormale Haut von Kopf, Perineum, den Genitalien, der Brustwarzen und der Extremitäten wurden mikroskopisch auf Milben und auf pathologische Befunde im Zusammenhang mit Milben untersucht.
Ergebnisse
Es wurden intrafollikuläre Milben in der Haut von 55% der Otter gefunden, wobei 20% von ihnen eine klinische Demodikose aufwiesen. Die Demodikose wurde als ursächlich für den Tod und die Euthanasie in zwei Fällen angesehen. Obwohl Demodex sp. Milben oft mikroskopisch in mit freiem Auge normaler Haut gefunden wurden, wurde das Vorkommen von multiplen dicht gepackten intrafollikulären Milben generell mit Pigmentinkontinenz, ektatischen Follikeln, lymphoplasmazytischer Perifollikulitis, und neutrophiler und lymphoplasmazytischer, dermaler Entzündung gesehen. Die Haut rundum den Mund, vor allem am Kinn, zeigte die höchste Prävalenz von Milben und die höchste Milbendichte, was auf einen Gesichtskontakt als Übertragungsweg für die Milben hinweist.
Schlussfolgerungen und klinische Bedeutung
Unsere Forschung bestätigte die Demodexmilbe als Beitragende zur Morbidität und Mortalität der Seeotter, was wichtige Implikationen für ihre klinische Versorgung, Rehabilitation und Erhaltung darstellt.
要約
背景
南方ラッコ (Enhydra lutris nereis)の体温調節は無傷の毛に依存するため、臨床的に著しいニキビダニ症およびそれに伴う脱毛症は、病的疾患や死亡の原因となることがある。
仮説/目的
本研究の目的は、毛包寄生性ニキビダニ属に関連する病変の記述、寄生の有病率および強度の推定、主要な解剖学的領域におけるダニの分布の記述、病変および宿主の危険因子との関連におけるダニの有無を評価することであった。
被験動物
2005年から2018年までカリフォルニア中央海岸で座礁した野生の南方ラッコ20頭を剖検した。
材料と方法
頭部、会陰部、生殖器、乳頭および四肢の総じて正常または異常な皮膚を顕微鏡的に評価し、ダニおよびダニに関連した病理学的所見を調査した。
結果
ラッコの55%の皮膚には毛包内にダニが観察され、20%には臨床的にニキビダニ症が認められた。そのうち2例は死亡または安楽死の原因と考えられた。正常な皮膚においてしばしばニキビダニが顕微鏡下で観察されたが、毛包内に密に詰まった複数のダニの存在は、一般的に色素脱、拡張性毛包、リンパ球形質細胞性毛包周囲炎、好中球性およびリンパ球形質細胞性の真皮の炎症と関連していた。その他の所見としては、表皮過形成、表皮および毛包漏斗部の正角化性角化亢進、膿皮症および細胞壊死を併発していた。口周囲の皮膚、特に顎部でダニの有病率が最も高く、ダニ密度も最も高かったことから、顔面接触がダニの感染手段であることが示唆された。
結論と臨床上の重要性
本研究は、ラッコの罹患率および死亡率の一因であるニキビダニを確認し、臨床ケア、リハビリテーション、管理に重要な意味を持つことを示した。
摘要
背景
方海獭依赖于被毛完整来进行体温调节, 因此具有临床意义的蠕形螨病和造成的脱毛可导致其发病和死亡。
假设/目的
本研究旨在描述毛囊蠕形螨侵染造成的病变, 评估侵染的流行率和严重程度, 描述关键解剖区域的螨虫分布, 并评估是否存在造成病变的螨虫, 以及宿主风险因素。
动物
2005年至2018年, 在加利福尼亚中部海岸搁浅并进行尸检的20只野生南方海獭。
方法和材料
采自外观正常和异常的头部、会阴、生殖器、乳头和四肢皮肤, 评估显微镜下螨虫及螨虫相关的病理学结果。
结果
在55%的水獭皮肤中观察到毛囊内螨虫, 20%患有临床蠕形螨病。在2个病例中, 蠕形螨病导致了死亡或因此而人道处死。尽管在外观正常的皮肤中, 通过显微镜经常能观察到蠕形螨虫体, 多处毛囊内出现的密集螨虫, 通常造成色素失禁、毛囊扩张、淋巴浆细胞性毛囊周炎以及中性粒细胞和淋巴浆细胞性真皮炎症。其他结果包括表皮增生、表皮和毛囊上皮的正角化性过度角化、并发脓皮病和细胞坏死。口周皮肤, 尤其是颏部, 螨虫侵染率最高, 螨虫密度最高, 这提示面部接触是螨虫传播的一种途径。
结论和临床重要性
我们的研究证实蠕形螨是海獭发病和死亡的因素, 临床护理、康复和保护具有重要意义。
Resumo
Contexto
As lontras do mar do Sul (Enhydra lutris nereis) dependem da pelagem intacta para termorregulação e, portanto, demodiciose clinicamente significativa e alopecia associada podem causar morbidade e morte.
Hipótese/Objetivos
Este estudo teve como objetivo descrever lesões associadas à infestação folicular por Demodex sp., estimar a prevalência e intensidade da infestação, descrever a distribuição de ácaros nas principais regiões anatômicas e avaliar a pr
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The existence of individual prey specializations has been reported for an ever-growing number of taxa, and has important ramifications for our understanding of predator–prey dynamics. We use the ...California sea otter population as a case study to validate the use of archival time–depth data to detect and measure differences in foraging behaviour and diet. We collected observational foraging data from radio-tagged sea otters that had been equipped with Mk9 time depth recorders (TDRs, Wildlife Computers, Redmond, WA). After recapturing the study animals and retrieving the TDRs it was possible to compare the two data types, by matching individual dives from the TDR record with observational data and thus examining behavioural correlates of capture success and prey species. Individuals varied with respect to prey selection, aggregating into one of three distinct dietary specializations. A number of TDR-derived parameters, particularly dive depth and post-dive surface interval, differed predictably between specialist types. A combination of six dive parameters was particularly useful for discriminating between specialist types, and when incorporated into a multivariate cluster analysis, these six parameters resulted in classification of 13 adult female sea otters into three clusters that corresponded almost perfectly to the diet-based classification (1 out of 13 animals was misclassified). Thus based solely on quantifiable traits of time–depth data that have been collected over an appropriate period (in this case 1 year per animal), it was possible to assign female sea otters to diet type with >90% accuracy. TDR data can thus be used as a tool to measure the degree of individual specialization in sea otter populations, a conclusion that will likely apply to other diving marine vertebrates as well. Our ultimate goals must be both to understand the causes of individual specialization, and to incorporate such variation into models of population- and community-level food web dynamics.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Sea urchin population demographics can respond to changes in keystone species abundances, with the magnitude of these responses varying depending on environmental influences. In this study, sea ...urchin populations were surveyed across 15 Aleutian archipelago islands over a 30-year period to understand how patterns of sea urchin demography (density, biomass, and size structure) varied through different ecological regimes that were caused by changes in the abundance of sea otters, a keystone species in this system. To examine long-term changes in sea urchin demographics, four time periods across the recent decline of sea otters were examined: during sea otter presence (1987-1994), nearing absence at the end of the decline (1997-2000), 10 years postdecline (2008-2010), and 15-20 years following the loss of sea otters from the ecosystem (2014-2017). Our results show that when sea otters were broadly present, sea urchin demographics were generally similar across the archipelago, with few urchins that had large-sized bodies. During this time, bottom-up environmental controls were muted relative to top-down forces from keystone predation. However, as sea otters declined and remained absent from the system, abiotic factors became more influential on sea urchin biomass, density, and size structure. In particular, differences among island groups during these periods were correlated with variation in ocean temperature, bathymetric complexity, and habitat availability. Sea urchin recruitment also varied among island groups, corresponding to ecoregions delineated by oceanic passes across the archipelago. The functional extinction of sea otters revealed an increasing influence of abiotic forcing in the absence of top-down control. This study further highlights the importance of understanding how keystone predators regulate herbivore demographics.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Ecological surprises, substantial and unanticipated changes in the abundance of one or more species that result from previously unsuspected processes, are a common outcome of both experiments and ...observations in community and population ecology. Here, we give examples of such surprises along with the results of a survey of well-established field ecologists, most of whom have encountered one or more surprises over the course of their careers. Truly surprising results are common enough to require their consideration in any reasonable effort to characterize nature and manage natural resources. We classify surprises as dynamic-, pattern-, or intervention-based, and we speculate on the common processes that cause ecological systems to so often surprise us. A long-standing and still growing concern in the ecological literature is how best to make predictions of future population and community dynamics. Although most work on this subject involves statistical aspects of data analysis and modeling, the frequency and nature of ecological surprises imply that uncertainty cannot be easily tamed through improved analytical procedures, and that prudent management of both exploited and conserved communities will require precautionary and adaptive management approaches.
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Ultra-compact device geometries requiring the development of new device technologies are essential for the successful implementation of active devices within photonic crystal systems. The basic ...operation of an ultra-compact silicon-based photonic crystal light modulator actuated by the thermo-optic modulation of the cut-off frequency about the telecommunication wavelength is discussed. A device design using highly localized high temperature resistive heating of heavily doped heating elements situated directly parallel to the photonic crystal light modulator was developed and evaluated using finite difference time domain and finite element analysis. These devices exhibited high extinction ratios and low insertion losses over a 40 nm frequency band around the telecommunication wavelength of 1550 nm with response times on the order of a few to several microseconds. The reliability implications of using these types of devices are discussed.
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