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1.
Aesthetic Plast Surg ; 2024 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-38480657

RESUMO

BACKGROUND: The inframammary fold (IMF) is an important landmark in breast aesthetic surgery. In augmentation mastopexy procedures, secure and accurate placement of the IMF is essential to aesthetic outcomes and to allow the new IMF to heal in the correct position without displacement. The authors present a simple and efficient four-layer wound closure technique using barbed sutures for closure of the repositioned IMF in augmentation mastopexy procedures. This method was previously described by the first author for reset of the IMF in breast augmentation surgery and has been adapted to the longer IMF incision in augmentation mastopexy procedures. METHODS: A retrospective review was undertaken of 335 patients who underwent bilateral breast augmentation mastopexy procedures with a Wise pattern technique at a single unit. The newly reset IMF was closed using barbed sutures and a four-layer closure technique. RESULTS: There were no cases of complications related to wound healing or wound dehiscence. One patient required explantation for an infected implant. CONCLUSION: The four-layer wound closure technique with barbed sutures provides a quick and efficient method for accurate closure of the newly reset IMF, with positive outcomes related to wound healing. Secure and accurate placement of the inframammary fold is crucial in augmentation mastopexy procedures. The use of a four-layer wound closure technique with barbed sutures provides an efficient method for accurate closure of the newly reset inframammary fold. This method was previously described by the first author for reset of the IMF in breast augmentation surgery and has been adapted to the longer IMF incision in augmentation mastopexy procedures. LEVEL OF EVIDENCE V: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

2.
Arch Plast Surg ; 50(5): 501-506, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37808330

RESUMO

This article portrays the authors' experience with a complex lower limb bone and soft tissue defect, following chronic osteomyelitis and pathological fracture, which was managed by the multidisciplinary orthoplastic team. The decision for functional amputation versus limb salvage was deemed necessary, enhanced by the principles of "spare parts" in reconstructive microsurgery. This case describes the successful use of the osteocutaneous distal tibia turn-up fillet flap that allowed "lowering the level of the amputation" from a through knee to a below-knee amputation (BKA) to preserve the knee joint function. We comprehensibly review reports of turn-up flaps which effectively lower the level of amputation, also applying "spare-parts" surgery principles and explore how these concepts refine complex orthoplastic approaches when limb salvage is not possible to enhance function. The osteocutaneous distal tibia turn-up fillet flap is a robust technique for modified BKA reconstructions that provides sufficient bone length to achieve a tough, sensate stump and functional knee joint.

3.
J Hand Surg Am ; 48(12): 1210-1216, 2023 12.
Artigo em Inglês | MEDLINE | ID: mdl-37737801

RESUMO

PURPOSE: Osteoporosis and fragility fractures incur substantial costs to quality of life and global health care systems. The current gold standard for quantifying bone density is dual-energy X-ray absorptiometry. Our hypothesis is that bone density can be accurately predicted with a simpler method using plain radiographs of the hand. METHODS: This retrospective cohort study was undertaken in two centers in the United Kingdom, where the second metacarpal cortical percentage (2MCP) scores were calculated from radiographs. This study included patients who had sustained a distal radius fracture between 2020 and 2022 and had received both a posteroanterior radiograph of the hand and a dual-energy X-ray absorptiometry scan within 12 months of their radiograph and fracture. The Pearson correlation coefficient was calculated to determine the correlation between 2MCP scores and t-scores of the femoral neck on dual-energy X-ray absorptiometry scans. RESULTS: Of the 188 patients, the 2MCP score significantly correlated with bone density t-scores of the femoral neck. A 2MCP score <50% demonstrated 100% sensitivity and 100% specificity for differentiating osteoporotic from normal subjects, whereas a 2MCP score <60% demonstrated 94.4% sensitivity and 83.0% specificity in differentiating osteopenic from normal subjects. CONCLUSIONS: These data confirm that the likelihood of osteoporosis being present can be determined via the 2MCP score. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic I.


Assuntos
Osteoporose , Fraturas por Osteoporose , Humanos , Absorciometria de Fóton , Densidade Óssea , Osteoporose/diagnóstico por imagem , Qualidade de Vida , Estudos Retrospectivos
4.
Aesthet Surg J ; 43(9): 972-977, 2023 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-36991214

RESUMO

BACKGROUND: Breast augmentation with implants is one of the most popular cosmetic surgery operations performed worldwide. Complications of breast implants are well recognized, and include capsular contracture, implant rupture, and infrequently distant migration of silicone, resulting in siliconoma. Distant migration of silicone can present many years after implantation with a wide variety of signs and symptoms. OBJECTIVES: The aim of this study was to describe the authors' experience of orbital silicone migration and to review the literature describing documented cases of distant silicon migration from breast implants, both ocular and nonocular. METHODS: In January 2022, a case of breast implant augmentation presented with silicone migration into the right orbit. This rare case was monitored and diagnosed with ocular muscle palsy and diplopia. Here, the authors present the patient's presenting complaint, symptomatology, working investigations, and outcomes. A comprehensive report of all available cases of distant silicone migration is presented along with their associated complications and more specifically ocular silicone migration. RESULTS: Systemic migration of silicone from breast implants to the orbital region is extremely rare: a total of 4 previous cases of ocular silicone migration from breast implants have been described previously; the authors describe the fifth case herein. CONCLUSIONS: Silicone implant rupture can present with a wide variety of clinical symptoms that may mimic different clinical pathologies. In every patient with a history of breast augmentation with silicone implants, the possibility of silicone migration should be always taken into consideration during the differential diagnosis process.


Assuntos
Implante Mamário , Implantes de Mama , Mamoplastia , Humanos , Implantes de Mama/efeitos adversos , Géis de Silicone/efeitos adversos , Implante Mamário/efeitos adversos , Implante Mamário/métodos , Mama
7.
J Plast Reconstr Aesthet Surg ; 76: 1-3, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36512991

RESUMO

In microsurgery training, where the first steps occur in a safe simulated environment, we believe there is a lack of emphasis on well reflected commonly occurring mistakes; education manuals provide stepwise instructions on performing tasks but do not list common mistakes and ways to avoid them. It is well acknowledged that the majority of vascular anastomotic complications are attributed to technical errors, however the validated global rating scales that are used to assess microsurgical competency do not address errors and how to avoid making them - potentially preventing devastating failures. Our aim is to improve and streamline constructive feedback in microsurgical education by use of an error-based learning resource. By referring to our '13 errors' graphic, teachers and students can refer to specific errors they have made, and quickly revise these with error-specific feedback, with and without supervision. The '13 errors' table enables identification errors, explanation as to why these may have occurred, and constructive feedback in order to rectify the mistake.


Assuntos
Doenças Cardiovasculares , Competência Clínica , Humanos , Anastomose Cirúrgica/educação , Avaliação Educacional , Escolaridade , Microcirurgia/educação
8.
Ecol Evol ; 11(16): 11333-11344, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34429922

RESUMO

The Southern Ocean has been disproportionately affected by climate change and is therefore an ideal place to study the influence of changing environmental conditions on ecosystems. Changes in the demography of predator populations are indicators of broader shifts in food web structure, but long-term data are required to study these effects. Southern elephant seals (Mirounga leonina) from Macquarie Island have consistently decreased in population size while all other major populations across the Southern Ocean have recently stabilized or are increasing. Two long-term mark-recapture studies (1956-1967 and 1993-2009) have monitored this population, which provides an opportunity to investigate demographic performance over a range of climatic conditions. Using a 9-state matrix population model, we estimated climate influences on female survival by incorporating two major climatic indices into our model: The Southern Annular Mode (SAM) and the Southern Oscillation Index (SOI). Our best model included a 1 year lagged effect of SAM and an unlagged SOI as covariates. A positive relationship with SAM1 (lagged) related the previous year's SAM with juvenile survival, potentially due to changes in local prey availability surrounding Macquarie Island. The unlagged SOI had a negative effect on both juvenile and adult seals, indicating that sea ice dynamics and access to foraging grounds on the East Antarctic continental shelf could explain the different contributions of ENSO events on the survival of females in this population.

9.
Opt Express ; 25(6): 6954-6962, 2017 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-28381037

RESUMO

The fluorescence spectra of titanium doped sapphire (Ti:Sapphire) crystals were measured for temperature ranging from 300K to 77K. The resulting gain cross-section line shapes were calculated and used in a three-dimensional amplification model to illustrate the importance of the precise knowledge of these fluorescence spectra for the design of cryogenic cooled Ti:Sapphire based chirped-pulse laser amplifiers.

10.
J Anim Ecol ; 86(2): 359-370, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-27859273

RESUMO

In mammals, maternal expenditure on offspring is a complex mix of several factors including the species' mating system, offspring sex and the condition and age of the mother. While theory suggests that in polygynous species mothers should wean larger male offspring than females when resources and maternal conditions allow, the evidence for this remains equivocal. Southern elephant seals are highly dimorphic, polygynous capital breeders existing in an environment with highly variable resources and should therefore provide clear evidence to support the theoretical expectations of differential maternal expenditure in male and female pups. We quantified maternal size (mass and length) and pup size at birth and weaning for 342 elephant seal mothers at Macquarie Island. The study was conducted over 11 years of contrasting sea-ice and Southern Annular Mode values, both indices of maternal prey resources. Overall, large females weaned male pups that weighed 17 kg (15·5%) more than female pups. Maternal condition varied by as much as 59 kg among years, and was positively related to Southern Annular Mode, and negatively to maximum sea-ice extent. Smaller mothers weaned relatively larger male pups under favourable conditions, this effect was less apparent for larger mothers. We developed a simple model linking environmental variation to maternal masses post-partum, followed by maternal masses post-partum to weaning masses and then weaning masses to pup survival and demonstrated that environmental conditions affected predicted survival so that the pups of small mothers had an estimated 7% increase in first year survival in 'good' vs. 'bad' years compared to 1% for female pups of large mothers. Co-occurrence of environmental quality and conservative reproductive tactics suggests that mothers retain substantial plasticity in maternal care, enhancing their lifetime reproductive success by adjusting reproductive expenditure relative to both prevailing environmental conditions and their own capabilities.


Assuntos
Peso Corporal , Reprodução , Focas Verdadeiras/fisiologia , Desmame , Animais , Feminino , Ilhas , Masculino , Modelos Biológicos , Mães , Focas Verdadeiras/crescimento & desenvolvimento , Estações do Ano , Tasmânia
11.
Proc Biol Sci ; 281(1782): 20132842, 2014 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-24619437

RESUMO

As the effects of regional climate change are most pronounced at polar latitudes, we might expect polar-ward migratory populations to respond as habitat suitability changes. The southern elephant seal (Mirounga leonina L.) is a pole-ward migratory species whose populations have mostly stabilized or increased in the past decade, the one exception being the Macquarie Island population which has decreased continuously over the past 50 years. To explore probable causes of this anomalous trend, we counted breeding female seals annually between 1988 and 2011 in order to relate annual rates of population change (r) to foraging habitat changes that have known connections with atmospheric variability. We found r (i) varied annually from -0.016 to 0.021 over the study period, (ii) was most effected by anomalous atmospheric variability after a 3 year time lag was introduced (R = 0.51) and (iii) was associated with sea-ice duration (SID) within the seals' foraging range at the same temporal lag. Negative r years may be extrapolated to explain, at least partially, the overall trend in seal abundance at Macquarie Island; specifically, increasing SID within the seals foraging range has a negative influence on their abundance at the island. Evidence is accruing that suggests southern elephant seal populations may respond positively to a reduced sea-ice field.


Assuntos
Ecossistema , Camada de Gelo , Focas Verdadeiras/fisiologia , Animais , Regiões Antárticas , Mudança Climática , Feminino , Dinâmica Populacional , Reprodução , Tasmânia
12.
Mar Pollut Bull ; 66(1-2): 199-208, 2013 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-23219394

RESUMO

The worlds' oceans contain a large but unknown amount of plastic debris. We made daily collections of marine debris stranded at two sub-Antarctic islands to establish (a) physical causes of strandings, and (b) a sampling protocol to better estimate the oceans' plastic loading. Accumulation rates at some beaches were dependent on tide and onshore winds. Most of the 6389 items collected were plastic (Macquarie 95%, Heard 94%) and discarded or lost fishing gear comprised 22% of those plastic items. Stalked barnacles (Lepas spp.) were a regular attachment on Macquarie debris but not at Heard Island. The daily accumulation rate of plastic debris on Macquarie Island was an order of magnitude higher than that estimated from monthly surveys during the same 4 months in the previous 5 years. This finding suggests that estimates of the oceans' plastic loading are an order of magnitude too low.


Assuntos
Plásticos/análise , Resíduos/análise , Poluentes da Água/análise , Poluição da Água/estatística & dados numéricos , Regiões Antárticas , Monitoramento Ambiental , Água do Mar/química , Resíduos/estatística & dados numéricos , Poluição da Água/análise
13.
Circulation ; 118(14 Suppl): S78-82, 2008 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-18824774

RESUMO

BACKGROUND: Surgical therapy of atrial fibrillation concomitant to coronary bypass grafting using epicardial Ultrasound technology was assessed after a minimum 6-month follow-up. METHODS AND RESULTS: A cohort of 98 consecutive patients with a mean age of 72+/-7.58 years and a primary diagnosis of ischemic heart disease had surgery for structural disease. Coronary artery bypass grafting was isolated (n=51) or associated (n=47) with various combinations of aortic, mitral, tricuspid, and left ventricular restoration surgery. Atrial fibrillation duration ranged from 6 to 360 months (mean 71 months) and was permanent in 47 patients, paroxysmal in 34, and persistent in 17. Left atrial mean diameter was 48+/-6.71 mm. A circumferential ablation was performed off-pump, before the concomitant procedure, and was always associated with an epicardial mitral line lesion using the same technology. At 3-, 6-, and 12-month visits, patients were routinely evaluated by physical examination, ECG, chest X-ray, and 24-hour Holter. There were 1 early death (1%) and 4 extracardiac late deaths. A pacemaker was implanted in 4 patients. Mean follow-up time was 325 days, 2 patients being lost to follow-up. Freedom from atrial fibrillation and flutter at the 6-month visit was 84% for the entire population, 76% in patients with permanent, and 91% in patients with paroxysmal atrial fibrillation. At the 1-year visit, 85% were free from atrial fibrillation or flutter. CONCLUSIONS: Epicardial beating heart ablation using therapeutic ultrasound is safe, reliable, and can easily treat atrial fibrillation in a difficult surgical population of patients with primary ischemic heart disease.


Assuntos
Fibrilação Atrial/cirurgia , Procedimentos Cirúrgicos Cardíacos , Isquemia Miocárdica/cirurgia , Pericárdio/cirurgia , Ultrassonografia de Intervenção , Idoso , Idoso de 80 Anos ou mais , Procedimentos Cirúrgicos Cardíacos/mortalidade , Estudos de Coortes , Ponte de Artéria Coronária , Feminino , Seguimentos , Valvas Cardíacas/cirurgia , Humanos , Complicações Intraoperatórias , Masculino , Complicações Pós-Operatórias , Resultado do Tratamento , Ultrassonografia de Intervenção/normas
14.
Ann Thorac Surg ; 84(6): 1978-83, 2007 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-18036920

RESUMO

BACKGROUND: Therapeutic ultrasound as an alternative to the maze procedure was evaluated in this large US experience. Safety and efficacy were assessed at 6-, 12-, and 18-month visits with systematic 24-hour Holter monitoring. METHODS: From February 2005 to February 2007, 220 patients were prospectively enrolled in a single center study, and among them 129 patients with concomitant cardiac surgery and at least 6-month follow-up were reviewed. Primary procedures were mitral surgery in 50% of the cases, coronary bypass in 32%, and aortic surgery in 16%. Atrial fibrillation was permanent in 66 (51.1%), paroxysmal in 43 (33.3%), and persistent in 20 (15.5%) patients. An epicardial and circumferential left atrial encircling line was created on the beating heart. Routinely a mitral isthmus line was also created from the left atrium epicardium using an ultrasonic handheld device. RESULTS: No morbidity or mortality was device-related. There were four (2.33%) early deaths and six late extra-cardiac deaths. Follow-up ranged from 6 to 670 days with a mean follow-up of 358.5 days, median 340 days with two patients lost to follow-up. Freedom from atrial fibrillation or left-sided flutter was 83.2%, 84.4%, and 86.2% at 6, 12, and 18 months, respectively. A pacemaker was implanted in seven patients (5.4%). Male gender and left atrial dimension were significant risk factors for failure. CONCLUSIONS: The study confirms the excellent safety record of the technology, and the efficacy at the level reported in a previous European multicenter study. Efficacy is also maintained at longer (12 and 18 months) follow-up.


Assuntos
Fibrilação Atrial/cirurgia , Ablação por Cateter/métodos , Terapia por Ultrassom , Adulto , Idoso , Idoso de 80 Anos ou mais , Aorta/cirurgia , Fibrilação Atrial/mortalidade , Ponte de Artéria Coronária , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Valva Mitral/cirurgia , Estudos Prospectivos , Resultado do Tratamento
15.
Ambio ; 34(6): 426-9, 2005 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16201211

RESUMO

This study addresses the consequences of repeated human handling on the survival of an endangered phocid, the southern elephant seal and the implications for wildlife research. Southern elephant seal pups were repeatedly handled during the first six weeks of their lives. The possibility that such anthropogenic research may have altered the very parameters that were being investigated is a topical and relevant study area that we address here. Our results show that there were no measurable effects on pups that were repeatedly handled and subjected to invasive research methods with respect to survivorship in the short term (the 24-day nursing period) nor in the long term (the first year of life and beyond) and hence fitness one year after handling. In support of this conclusion we were unable to detect any significant differences in the survival rates of the most intensively handled seals and the least intensively handled seals.


Assuntos
Animais Selvagens , Focas Verdadeiras , Animais , Austrália , Taxa de Sobrevida
16.
Proc Biol Sci ; 272(1566): 923-8, 2005 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-16024347

RESUMO

Maternal and physical factors play a significant role in animal life-history variability, which means that large scale climate change has the potential to affect the size and dynamics of animal populations indirectly through maternal investment and directly through conditions that animals are exposed to. However, little is known about the effects of large-scale oceanographic events such as the El-Niño southern oscillation (ENSO) that influence productivity in the Southern Ocean and the abundance, quality and distribution of prey. The possible mechanisms by which physical factors and primary productivity could influence life-history traits, such as survival of apex predators, includes direct influences such as food availability and foraging success and indirect influences such as stored maternal investment and resource transfer during lactation. Here, we quantify the relative contribution of maternal investment and climate conditions at remote foraging sites to survival in the first year of life for southern elephant seals. We present evidence linking climate (ENSO) and variations in a key demographic parameter--first-year survival--and demonstrate that survival was highest during ENSO events and that the ability of mothers to store and acquire resources, which is typically related to ocean productivity, is the most important determinant of survival in the first year. This functional link provides valuable insights that can be used to model the responses of the seal populations to climate change scenarios.


Assuntos
Clima , Meio Ambiente , Focas Verdadeiras/fisiologia , Sobrevida/fisiologia , Animais , Regiões Antárticas , Comportamento Alimentar/fisiologia , Comportamento Materno/fisiologia , Modelos Biológicos , Análise de Sobrevida
17.
Physiol Biochem Zool ; 78(4): 491-504, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-15957104

RESUMO

Growing juvenile animals undergo many morphological, physiological, and behavioural changes that influence their energetic requirements, patterns of energy use, and ultimately, their survival and reproductive success. We examined changes in mass loss and body composition of juvenile southern elephant seals (1- and 2-yr-olds) during their two annual haul-outs. At the start and end of the midyear and molt haul-outs, we caught, weighed, and measured 41 and 14 seals, respectively. We measured blubber depth using ultrasound to estimate body composition (lean and adipose tissue mass). Using energy densities of the adipose and lean tissue, we calculated total, lean, and adipose mass changes and energy expenditure. While molting, juvenile seals used more energy than during the midyear, which is related to the increased use of lean tissue for hair and skin regeneration. The amount of energy used increases with mass as individuals mature. We found sexual differences in energy use where females retained greater fat reserves than males by utilizing more lean tissue. These differences are most likely related to haul-out function and behavior, growth, and earlier development of females toward sexual maturity.


Assuntos
Metabolismo Energético/fisiologia , Metabolismo dos Lipídeos , Proteínas/metabolismo , Focas Verdadeiras/fisiologia , Estações do Ano , Tecido Adiposo/diagnóstico por imagem , Animais , Regiões Antárticas , Composição Corporal , Pesos e Medidas Corporais , Feminino , Modelos Lineares , Masculino , Focas Verdadeiras/crescimento & desenvolvimento , Fatores Sexuais , Ultrassonografia
18.
Oecologia ; 142(1): 127-35, 2005 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-15365810

RESUMO

In highly dynamic and unpredictable environments such as the Southern Ocean, species that have evolved behaviors that reduce the effects of intra-specific competition may have a selective advantage. This is particularly true when juveniles face disadvantages when foraging due to morphological or physiological limitation, which is the case for many marine mammals. We tracked the at-sea movements of 48 juvenile southern elephant seals ( Mirounga leonina) between the ages of 1 and 4 years from the population at Macquarie Island using locations derived from recorded light levels. There were significant differences in the total amount of the Southern Ocean covered by the different age-groups. The younger seals used a smaller area than the older seals. On average, the younger individuals also made more trips to sea than the older seals and did not travel as far on each trip. Females spent more time at sea than males and there were no significant differences between the total areas used by male and females. In summary, younger seals remained closer to the island at all times, and they spent more time in more northerly regions that older seals. These differences in behavior created temporal and spatial segregation between juveniles of different ages. Therefore, we suggest that these temporal and spatial separations help to avoid intra-specific competition for resources on land, space on beaches, and at-sea foraging areas. Such modifications of haul-out timing and behavior enable them to exploit a patchy and unpredictable environment.


Assuntos
Comportamento Competitivo/fisiologia , Comportamento Alimentar/fisiologia , Focas Verdadeiras/fisiologia , Comportamento Espacial/fisiologia , Fatores Etários , Animais , Feminino , Geografia , Luz , Masculino , Oceanos e Mares , Fatores Sexuais , Temperatura , Fatores de Tempo
19.
Ambio ; 32(6): 380-4, 2003 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-14627365

RESUMO

One hundred and sixty four plastic particles (mean length 4.1 mm) recovered from the scats of fur seals (Arctocephalus spp.) on Macquarie Island were examined. Electron micrographs of 41 of the plastic particles showed that none could be identified as plastic pellet feedstock from their shapes. Commonly, such pellets are cylindrical and spherical. Instead, all the 164 plastic particles from the seal scats were angular particles of 7 colors (feedstock particles are normally opaque or white) and could be classified into 2 categories: i) fragmented along crystal lines and likely to be the result of UV breakdown; and ii) worn by abrasion (where striations were clearly visible) into irregular shapes with rounded corners. White, brown, green, yellow and blue were the most common colors. In composition, they came from 5 polymer groups; polyethylene 93%, polypropylene 4%, poly(1-Cl-1-butenylene) polychloroprene 2%, melamine-urea (phenol) (formaldehyde) resin 0.5%, and cellulose (rope fiber) 0.5%. The larger groups are buoyant with a specific gravity less than that of seawater. These small plastic particles are formed from the breakdown of larger particles (fragments). Their origin seems to be from the breakdown of user plastics washed ashore and ground down on cobbled beaches. Certainly most particles (70%) had attained their final form by active abrasion. It is hypothesized that the plastic particles were washed out to sea and then selected by size and consumed by individuals of a pelagic fish species, Electrona subaspera, who in turn were consumed by the fur seals. Thus, the particles were accumulated both by the fish and the seals in the usual process of their feeding.


Assuntos
Otárias , Plásticos/farmacocinética , Poluentes da Água/farmacocinética , Animais , Austrália , Dieta , Fezes/química , Peixes , Cadeia Alimentar , Geografia , Microscopia Eletrônica de Varredura , Tamanho da Partícula , Distribuição Tecidual
20.
J Exp Biol ; 206(Pt 19): 3405-23, 2003 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-12939372

RESUMO

Elephant seals regularly perform dives during which they spend a large proportion of time drifting passively through the water column. The rate of vertical change in depth during these "drift" dives is largely a result of the proportion of lipid tissue in the body, with fatter seals having higher (more positive or less negative) drift rates compared with leaner seals. We examined the temporal changes in drift rates of 24 newly weaned southern elephant seal (Mirounga leonina) pups during their first trip to sea to determine if this easily recorded dive characteristic can be used to continuously monitor changes in body composition of seals throughout their foraging trips. All seals demonstrated a similar trend over time: drift rates were initially positive but decreased steadily over the first 30-50 days after departure (Phase 1), corresponding to seals becoming gradually less buoyant. Over the following approximately 100 days (Phase 2), drift rates again increased gradually, while during the last approximately 20-45 days (Phase 3) drift rates either remained constant or decreased slightly. The daily rate of change in drift rate was negatively related to the daily rate of horizontal displacement (daily travel rate), and daily travel rates of more than approximately 80 km were almost exclusively associated with negative changes in drift rate. We developed a mechanistic model based on body compositions and morphometrics measured in the field, published values for the density of seawater and various body components, and values of drag coefficients for objects of different shapes. We used this model to examine the theoretical relationships between drift rate and body composition and carried out a sensitivity analysis to quantify errors and biases caused by varying model parameters. While variations in seawater density and uncertainties in estimated body surface area and volume are unlikely to result in errors in estimated lipid content of more than +/-2.5%, variations in drag coefficient can lead to errors of >or =10%. Finally, we compared the lipid contents predicted by our model with the lipid contents measured using isotopically labelled water and found a strong positive correlation. The best-fitting model suggests that the drag coefficient of seals while drifting passively is between approximately 0.49 (roughly corresponding to a sphere-shaped object) and 0.69 (a prolate spheroid), and we were able to estimate relative lipid content to within approximately +/-2% lipid. Our results suggest that this simple method can be used to estimate the changes in lipid content of free-ranging seals while at sea and may help improve our understanding of the foraging strategies of these important marine predators.


Assuntos
Tecido Adiposo/fisiologia , Composição Corporal/fisiologia , Mergulho/fisiologia , Modelos Biológicos , Movimento/fisiologia , Focas Verdadeiras/fisiologia , Animais , Regiões Antárticas , Fenômenos Biomecânicos , Lipídeos/análise , Projetos de Pesquisa , Comunicações Via Satélite , Água do Mar , Telemetria
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