Science.gov

Sample records for profundidad haliporoides diomedeae

  1. Field behavior of the nudibranch mollusc Tritonia diomedea.

    PubMed

    Wyeth, Russell C; Willows, A O Dennis

    2006-04-01

    The nudibranch mollusc Tritonia diomedea has been a useful model system for studies of how the brain controls behavior. However, no broad study of T. diomedea field behavior exists--an important deficit since laboratory behaviors may differ from what occurs in nature. Here we report analysis of time-lapse video of the slugs in their natural habitat to describe behaviors and their relationships to sensory cues. We found that movements relative to conspecifics, prey, and predators correlated with direction of water flow. These observations lead to three new navigational hypotheses: regardless of the actual heading to the target, T. diomedea crawls (1) upstream toward potential mates, (2) upstream toward food, and (3) downstream away from predators. We also describe both the behavior and its sensory context for feeding, escape swims, mating, and egg-laying, among other behaviors. Field behaviors were similar to published descriptions of laboratory behavior. However, the field observations add contextual detail, including preceding and subsequent behaviors and interactions with suites of habitat features not present in the laboratory. For example, the escape swim, previously studied as an isolated behavior in response to a single stimulus, appears to be affected by multiple sensory modalities and coordinated with several other behaviors. Our work will provide a basis for future neuroethological experimentation and also is the first step in the study of navigation in T. diomedea. PMID:16641514

  2. The short-tailed Albatross, Diomedea albatrus, its status, distribution and natural history

    USGS Publications Warehouse

    Hasegawa, H.; DeGange, A.R.

    1982-01-01

    The Short-tailed Albatross (Diomedea albatrus) is presently an Endangered Species that was formerly abundant in the North Pacific. Owing to the activities of feather hunters operating on the albatross's nesting grounds for a 50-year period in the late 19th and early 20th centuries, the species was almost reduced to extinction. The Short-tailed Albatross is the largest of the three species of Diomedea that breed in the North Pacific (Table 1) and when mature is the only albatross in the North Pacific with a white back.

  3. Evidence for olfactory search in wandering albatross, Diomedea exulans

    PubMed Central

    Nevitt, Gabrielle A.; Losekoot, Marcel; Weimerskirch, Henri

    2008-01-01

    Wandering albatrosses (Diomedea exulans) forage over thousands of square kilometers of open ocean for patchily distributed live prey and carrion. These birds have large olfactory bulbs and respond to fishy-scented odors in at-sea trials, suggesting that olfaction plays a role in natural foraging behavior. With the advent of new, fine-scale tracking technologies, we are beginning to explore how birds track prey in the pelagic environment, and we relate these observations to models of odor transport in natural situations. These models suggest that odors emanating from prey will tend to disperse laterally and downwind of the odor source and acquire an irregular and patchy concentration distribution due to turbulent transport. For a seabird foraging over the ocean, this scenario suggests that olfactory search would be facilitated by crosswind flight to optimize the probability of encountering a plume emanating from a prey item, followed by upwind, zigzag flight to localize the prey. By contrast, birds approaching prey by sight would be expected to fly directly to a prey item, irrespective of wind direction. Using high-precision global positioning system (GPS) loggers in conjunction with stomach temperature recorders to simultaneously monitor feeding events, we confirm these predictions in freely ranging wandering albatrosses. We found that initial olfactory detection was implicated in nearly half (46.8%) of all flown approaches preceding prey-capture events, accounting for 45.5% of total prey mass captured by in-flight foraging. These results offer insights into the sensory basis for area-restricted search at the large spatial scales of the open ocean. PMID:18326025

  4. Orientation and navigation relative to water flow, prey, conspecifics, and predators by the nudibranch mollusc Tritonia diomedea.

    PubMed

    Wyeth, Russell C; Woodward, Owen M; Willows, A O Dennis

    2006-04-01

    Progress in understanding sensory and locomotory systems in Tritonia diomedea has created the potential for the neuroethological study of animal navigation in this species. Our goal is to describe the navigational behaviors to guide further work on how the nervous system integrates information from multiple senses to produce oriented locomotion. Observation of T. diomedea in its habitat has suggested that it uses water flow to navigate relative to prey, predators, and conspecifics. We test these hypotheses in the field by comparing slug orientation in time-lapse videos to flow direction in circumstances with and without prey, predators, or conspecifics upstream. T. diomedea oriented upstream both while crawling and after turning. This trend was strongest before feeding or mating; after feeding or mating, the slugs did not orient significantly to flow. Slugs turned downstream away from an upstream predator but did not react in control situations without an upstream predator. These data support the hypothesis that T. diomedea uses a combination of odors (or some other cue transported downstream) and water flow to navigate relative to prey, predators, and conspecifics. Understanding the context-dependent choice between upstream and downstream crawling in T. diomedea provides an opportunity for further work on the sensory integration underlying navigation behavior. PMID:16641515

  5. The homing behaviour of Cory's shearwaters (Calonectris diomedea) studied by means of a direction recorder

    PubMed

    Antonia; Antonia; Benvenuti; IoalÈ; Massa; Bonadonna

    1995-01-01

    A direction recorder, which can be carried by a flying bird on its back, has been used for the first time on a wild species. The device can detect and record the direction in which a bird is heading during flight. Cory's shearwaters (Calonectris diomedea) were moved from their nesting colony to five different sites and fitted with direction recorders, and four homing flight paths were obtained. Our data show that the displaced birds were able to assume and maintain a homeward course soon after release over large areas of open sea, completely devoid of guiding features; topographical elements are, therefore, not necessary for correct orientation.

  6. Odours detected by rhinophores mediate orientation to flow in the nudibranch mollusc, Tritonia diomedea.

    PubMed

    Wyeth, Russell C; Willows, A O Dennis

    2006-04-01

    Tritonia diomedea is a useful neuroethological model system that can contribute to our understanding of the neural control of navigation. Prior work on both sensory and locomotory systems is complemented by recent field experiments, which concluded that these animals primarily use a combination of odours and water flow as guidance cues. We corroborate these field results by showing similar navigation behaviours in a flow tank. Slugs crawled upstream towards both prey and conspecifics, and turned downstream after crawling into a section of the flow tank downstream of a predator. Controls without upstream odour sources crawled apparently randomly. We then tested whether these behaviours depend on odours detected by the rhinophores. Outflow from a header tank was used to generate prey, predator and unscented control odour plumes in the flow tank. Slugs with rhinophores crawled upstream towards a prey odour plume source, turned downstream in a predator odour plume, and showed no reaction to a control plume. Slugs without rhinophores behaved similarly to controls, regardless of odour plume type. Finally, we used extracellular recordings from the rhinophore nerve to demonstrate that isolated rhinophores are chemosensitive. Afferent activity increased significantly more after application of all three odour types than after unscented control applications. Responses were odour specific. We conclude that rhinophores mediate orientation to flow, and suggest that future work should focus on the integration of mechanosensation and chemosensation during navigation in T. diomedea. PMID:16574804

  7. Odours detected by rhinophores mediate orientation to flow in the nudibranch mollusc, Tritonia diomedea.

    PubMed

    Wyeth, Russell C; Willows, A O Dennis

    2006-04-01

    Tritonia diomedea is a useful neuroethological model system that can contribute to our understanding of the neural control of navigation. Prior work on both sensory and locomotory systems is complemented by recent field experiments, which concluded that these animals primarily use a combination of odours and water flow as guidance cues. We corroborate these field results by showing similar navigation behaviours in a flow tank. Slugs crawled upstream towards both prey and conspecifics, and turned downstream after crawling into a section of the flow tank downstream of a predator. Controls without upstream odour sources crawled apparently randomly. We then tested whether these behaviours depend on odours detected by the rhinophores. Outflow from a header tank was used to generate prey, predator and unscented control odour plumes in the flow tank. Slugs with rhinophores crawled upstream towards a prey odour plume source, turned downstream in a predator odour plume, and showed no reaction to a control plume. Slugs without rhinophores behaved similarly to controls, regardless of odour plume type. Finally, we used extracellular recordings from the rhinophore nerve to demonstrate that isolated rhinophores are chemosensitive. Afferent activity increased significantly more after application of all three odour types than after unscented control applications. Responses were odour specific. We conclude that rhinophores mediate orientation to flow, and suggest that future work should focus on the integration of mechanosensation and chemosensation during navigation in T. diomedea.

  8. The Mitochondrial Genomes of the Nudibranch Mollusks, Melibe leonina and Tritonia diomedea, and Their Impact on Gastropod Phylogeny.

    PubMed

    Sevigny, Joseph L; Kirouac, Lauren E; Thomas, William Kelley; Ramsdell, Jordan S; Lawlor, Kayla E; Sharifi, Osman; Grewal, Simarvir; Baysdorfer, Christopher; Curr, Kenneth; Naimie, Amanda A; Okamoto, Kazufusa; Murray, James A; Newcomb, James M

    2015-01-01

    The phylogenetic relationships among certain groups of gastropods have remained unresolved in recent studies, especially in the diverse subclass Opisthobranchia, where nudibranchs have been poorly represented. Here we present the complete mitochondrial genomes of Melibe leonina and Tritonia diomedea (more recently named T. tetraquetra), two nudibranchs from the unrepresented Cladobranchia group, and report on the resulting phylogenetic analyses. Both genomes coded for the typical thirteen protein-coding genes, twenty-two transfer RNAs, and two ribosomal RNAs seen in other species. The twelve-nucleotide deletion previously reported for the cytochrome oxidase 1 gene in several other Melibe species was further clarified as three separate deletion events. These deletions were not present in any opisthobranchs examined in our study, including the newly sequenced M. leonina or T. diomedea, suggesting that these previously reported deletions may represent more recently divergent taxa. Analysis of the secondary structures for all twenty-two tRNAs of both M. leonina and T. diomedea indicated truncated d arms for the two serine tRNAs, as seen in some other heterobranchs. In addition, the serine 1 tRNA in T. diomedea contained an anticodon not yet reported in any other gastropod. For phylogenetic analysis, we used the thirteen protein-coding genes from the mitochondrial genomes of M. leonina, T. diomedea, and seventy-one other gastropods. Phylogenetic analyses were performed for both the class Gastropoda and the subclass Opisthobranchia. Both Bayesian and maximum likelihood analyses resulted in similar tree topologies. In the Opisthobranchia, the five orders represented in our study were monophyletic (Anaspidea, Cephalaspidea, Notaspidea, Nudibranchia, Sacoglossa). In Gastropoda, two of the three traditional subclasses, Opisthobranchia and Pulmonata, were not monophyletic. In contrast, four of the more recently named gastropod clades (Vetigastropoda, Neritimorpha

  9. The Mitochondrial Genomes of the Nudibranch Mollusks, Melibe leonina and Tritonia diomedea, and Their Impact on Gastropod Phylogeny

    PubMed Central

    Sevigny, Joseph L.; Kirouac, Lauren E.; Thomas, William Kelley; Ramsdell, Jordan S.; Lawlor, Kayla E.; Sharifi, Osman; Grewal, Simarvir; Baysdorfer, Christopher; Curr, Kenneth; Naimie, Amanda A.; Okamoto, Kazufusa; Murray, James A.; Newcomb, James M.

    2015-01-01

    The phylogenetic relationships among certain groups of gastropods have remained unresolved in recent studies, especially in the diverse subclass Opisthobranchia, where nudibranchs have been poorly represented. Here we present the complete mitochondrial genomes of Melibe leonina and Tritonia diomedea (more recently named T. tetraquetra), two nudibranchs from the unrepresented Cladobranchia group, and report on the resulting phylogenetic analyses. Both genomes coded for the typical thirteen protein-coding genes, twenty-two transfer RNAs, and two ribosomal RNAs seen in other species. The twelve-nucleotide deletion previously reported for the cytochrome oxidase 1 gene in several other Melibe species was further clarified as three separate deletion events. These deletions were not present in any opisthobranchs examined in our study, including the newly sequenced M. leonina or T. diomedea, suggesting that these previously reported deletions may represent more recently divergent taxa. Analysis of the secondary structures for all twenty-two tRNAs of both M. leonina and T. diomedea indicated truncated d arms for the two serine tRNAs, as seen in some other heterobranchs. In addition, the serine 1 tRNA in T. diomedea contained an anticodon not yet reported in any other gastropod. For phylogenetic analysis, we used the thirteen protein-coding genes from the mitochondrial genomes of M. leonina, T. diomedea, and seventy-one other gastropods. Phylogenetic analyses were performed for both the class Gastropoda and the subclass Opisthobranchia. Both Bayesian and maximum likelihood analyses resulted in similar tree topologies. In the Opisthobranchia, the five orders represented in our study were monophyletic (Anaspidea, Cephalaspidea, Notaspidea, Nudibranchia, Sacoglossa). In Gastropoda, two of the three traditional subclasses, Opisthobranchia and Pulmonata, were not monophyletic. In contrast, four of the more recently named gastropod clades (Vetigastropoda, Neritimorpha

  10. Oxidative stress predicts long-term resight probability and reproductive success in Scopoli's shearwater (Calonectris diomedea)

    PubMed Central

    Costantini, David; Dell'Omo, Giacomo

    2015-01-01

    A major challenge in conservation physiology is to find out biomarkers that reliably reflect individual variation in wear and tear. Recent work has suggested that biomarkers of oxidative stress may provide an additional tool to assess the health state of individuals and to predict fitness perspectives. In this study, we assessed whether three biomarkers of plasma oxidative status predicted the following factors: (i) the resight probability as breeder in the next seasons; and (ii) the cumulative reproductive output over multiple years in Scopoli’s shearwaters (Calonectris diomedea) using a 7 year individual-based data set. Our results show that shearwaters having higher levels of a marker of oxidative damage (reactive oxygen metabolites) in 2008 had a lower resight probability in the next years and a lower number of chicks raised from 2008 to 2014. In contrast, two biomarkers of antioxidant defences (non-enzymatic antioxidant capacity of plasma and thiols) did not have any predictive value. Increased concentrations of plasma reactive oxygen metabolites, together with the significant individual repeatability over time in this metric of oxidative stress found in numerous studies, suggest that this metric might serve as a blood-derived biomarker for health and fitness perspectives in birds and, possibly, also in other taxa. PMID:27293709

  11. Demographic Responses to Oxidative Stress and Inflammation in the Wandering Albatross (Diomedea exulans)

    PubMed Central

    Costantini, David; Goutte, Aurelie; Barbraud, Christophe; Faivre, Bruno; Sorci, Gabriele; Weimerskirch, Henri; Delord, Karine; Chastel, Olivier

    2015-01-01

    One of the major challenges in ecological research is the elucidation of physiological mechanisms that underlie the demographic traits of wild animals. We have assessed whether a marker of plasma oxidative stress (TBARS) and plasma haptoglobin (protein of the acute inflammatory phase response) measured at time t predict five demographic parameters (survival rate, return rate to the breeding colony, breeding probability, hatching and fledging success) in sexually mature wandering albatrosses over the next four years (Diomedea exulans) using a five-year individual-based dataset. Non-breeder males, but not females, having higher TBARS at time t had reduced future breeding probabilities; haptoglobin was not related to breeding probability. Neither TBARS nor haptoglobin predicted future hatching or fledging success. Haptoglobin had a marginally positive effect on female survival rate, while TBARS had a marginally negative effect on return rate. Our findings do not support the role for oxidative stress as a constraint of future reproductive success in the albatross. However, our data point to a potential mechanism underlying some aspects of reproductive senescence and survival. Our results also highlight that the study of the consequences of oxidative stress should consider the life-cycle stage of an individual and its reproductive history. PMID:26275171

  12. Nonassociative learning processes affecting swimming probability in the seaslug Tritonia diomedea: habituation, sensitization and inhibition.

    PubMed

    Brown, G D

    1998-10-01

    The role of nonassociative learning processes in determining whether or not a chemical stimulus will elicit the Tritonia diomedea swimming response was examined in a variety of conditioning experiments. Iterative presentation of a chemical stimulus resulted in a reduced swimming probability (SP). By the criteria of Thompson and Spencer (Thompson RF, Spencer WA. Psychol. Rev. 1966;73:16-43) and others, this iterative reduction of SP was concluded to be the result of habituation. Site-specificity and a below zero effect implicated sensory pathways in habituation memory storage. The iterative reduction in SP was reversible, confirming that a sensitization-like process can also influence SP. It was further concluded that a short-term decrement in swimming cycle number was most likely due to a constraint in the effector pathway. Experience with a tactile stimulus had a long-lasting decremental effect on SP. This heterostimic reduction of SP was amplified in a multistimic paradigm that included both chemical and tactile stimuli during training. The chemical stimuli alone did not alter SP in this experiment. Multistimic reduction lasted for a week and was reversed temporarily by an excitatory chemical stimulus. The long-lasting reduction of SP by tactile stimulation appears to be the result of a novel nonassociative inhibitory process, which was distinguished from other learning processes by its duration and specificity. A total of three distinct learning processes are postulated to account for the role of simple types of experience in determining SP in Tritonia: habituation, sensitization, and nonassociative inhibition.

  13. Demographic Responses to Oxidative Stress and Inflammation in the Wandering Albatross (Diomedea exulans).

    PubMed

    Costantini, David; Goutte, Aurelie; Barbraud, Christophe; Faivre, Bruno; Sorci, Gabriele; Weimerskirch, Henri; Delord, Karine; Chastel, Olivier

    2015-01-01

    One of the major challenges in ecological research is the elucidation of physiological mechanisms that underlie the demographic traits of wild animals. We have assessed whether a marker of plasma oxidative stress (TBARS) and plasma haptoglobin (protein of the acute inflammatory phase response) measured at time t predict five demographic parameters (survival rate, return rate to the breeding colony, breeding probability, hatching and fledging success) in sexually mature wandering albatrosses over the next four years (Diomedea exulans) using a five-year individual-based dataset. Non-breeder males, but not females, having higher TBARS at time t had reduced future breeding probabilities; haptoglobin was not related to breeding probability. Neither TBARS nor haptoglobin predicted future hatching or fledging success. Haptoglobin had a marginally positive effect on female survival rate, while TBARS had a marginally negative effect on return rate. Our findings do not support the role for oxidative stress as a constraint of future reproductive success in the albatross. However, our data point to a potential mechanism underlying some aspects of reproductive senescence and survival. Our results also highlight that the study of the consequences of oxidative stress should consider the life-cycle stage of an individual and its reproductive history. PMID:26275171

  14. One rhinophore probably provides sufficient sensory input for odour-based navigation by the nudibranch mollusc Tritonia diomedea.

    PubMed

    McCullagh, Gregory B; Bishop, Cory D; Wyeth, Russell C

    2014-12-01

    Tritonia diomedea (synonymous with Tritonia tetraquetra) navigates in turbulent odour plumes, crawling upstream towards prey and downstream to avoid predators. This is probably accomplished by odour-gated rheotaxis, but other possibilities have not been excluded. Our goal was to test whether T. diomedea uses odour-gated rheotaxis and to simultaneously determine which of the cephalic sensory organs (rhinophores and oral veil) are required for navigation. In a first experiment, slugs showed no coherent responses to streams of odour directed at single rhinophores. In a second experiment, navigation in prey and predator odour plumes was compared between animals with unilateral rhinophore lesions, denervated oral veils, or combined unilateral rhinophore lesions and denervated oral veils. In all treatments, animals navigated in a similar manner to that of control and sham-operated animals, indicating that a single rhinophore provides sufficient sensory input for navigation (assuming that a distributed flow measurement system would also be affected by the denervations). Amongst various potential navigational strategies, only odour-gated positive rheotaxis can produce the navigation tracks we observed in prey plumes while receiving input from a single sensor. Thus, we provide strong evidence that T. diomedea uses odour-gated rheotaxis in attractive odour plumes, with odours and flow detected by the rhinophores. In predator plumes, slugs turned downstream to varying degrees rather than orienting directly downstream for crawling, resulting in greater dispersion for negative rheotaxis in aversive plumes. These conclusions are the first explicit confirmation of odour-gated rheotaxis as a navigational strategy in gastropods and are also a foundation for exploring the neural circuits that mediate odour-gated rheotaxis. PMID:25324338

  15. Nervous control of ciliary beating by Cl(-), Ca(2+) and calmodulin in Tritonia diomedea.

    PubMed

    Woodward, Owen M; Willows, A O Dennis

    2006-07-01

    In vertebrates, motile cilia line airways, oviducts and ventricles. Invertebrate cilia often control feeding, swimming and crawling, or gliding. Yet control and coordination of ciliary beating remains poorly understood. Evidence from the nudibranch mollusc, Tritonia diomedea, suggests that locomotory ciliated epithelial cells may be under direct electrical control. Here we report that depolarization of ciliated pedal epithelial (CPE) cells increases ciliary beating frequency (CBF), and elicits CBF increases similar to those caused by dopamine and the neuropeptide, TPep-NLS. Further, four CBF stimulants (zero external Cl(-), depolarization, dopamine and TPep-NLS) depend on a common mode of action, viz. Ca(2+) influx, possibly through voltage-gated Ca(2+) channels, and can be blocked by nifedipine. Ca(2+) influx alone, however, does not provide all the internal Ca(2+) necessary for CBF change. Ryanodine receptor (RyR) channel-gated internal stores are also necessary for CBF excitation. Caffeine can stimulate CBF and is sensitive to the presence of the RyR blocker dantrolene. Dantrolene also reduces CBF excitation induced by dopamine and TPep-NLS. Finally, W-7 and calmidazolium both block CBF excitation by caffeine and dopamine, and W-7 is effective at blocking TPep-NLS excitation. The effects of calmidazolium and W-7 suggest a role for Ca(2+)-calmodulin in regulating CBF, either directly or via Ca(2+)-calmodulin dependent kinases or phosphodiesterases. From these results we hypothesize dopamine and TPep-NLS induce depolarization-driven Ca(2+) influx and Ca(2+) release from internal stores that activates Ca(2+)-calmodulin, thereby increasing CBF. PMID:16809467

  16. A new perspective on the growth pattern of the Wandering Albatross (Diomedea exulans) through DEB theory

    NASA Astrophysics Data System (ADS)

    Teixeira, Carlos M. G. L.; Sousa, Tânia; Marques, Gonçalo M.; Domingos, Tiago; Kooijman, Sebastiaan A. L. M.

    2014-11-01

    The Wandering Albatross (Diomedea exulans) and other seabirds exhibit a growing pattern that includes a period of body mass decrease before fledging. Several hypotheses have been suggested to explain it without success. We hypothesized that: 1) chicks and adults have similar metabolic traits regulating assimilation, growth and maturation; 2) there is a difference in locomotion effort between chicks and adults, and 3) chicks are exposed to a decline in food availability before fledging. This set of hypotheses allows for an energy surplus to be available and stored in reserve during the first months of development, explaining the mass recession that starts before fledging and the fact that adults keep a lower weight than fledglings, throughout the rest of their life span. To test this set of hypotheses we applied the Dynamic Energy Budget (DEB) theory. Using a small set of life-history traits and growth curves we parameterized the DEB standard model. We confirmed this set of hypotheses and estimated the pattern of decline in food availability that explains mass recession. An assessment of the daily energy intake was also performed. The implications related to that energy flux and diet composition are discussed based on current knowledge. The DEB model for the Wandering Albatross also provided estimates for the adult daily food ingested by adults (464.06 kJ kg- 1 d- 1), fasting capacity (25 d), Field Metabolic Rate (4.29 W kg- 1) and resting metabolic rate (2.87 W kg- 1). These values are consistent with the averages obtained in the field, suggesting that DEB may be useful to provide good estimations on a broader scale.

  17. Pedal neuron 3 serves a significant role in effecting turning during crawling by the marine slug Tritonia diomedea (Bergh).

    PubMed

    Redondo, Roger L; Murray, James A

    2005-05-01

    The marine nudibranch Tritonia diomedea crawls using its ciliated foot surface as the sole means of propulsion. Turning while crawling involves raising a small portion of the lateral foot margin on the side of the turn. The cilia in the lifted area no longer contribute to propulsion, and this asymmetry in thrust turns the animal towards the lifted side. Neurons located in the pedal ganglia of the brain contribute to these foot margin contractions. T. diomedea has a natural tendency to turn upstream (rheotaxis), and pedal flexion neuron Pedal 3 elicits foot margin lift and receives modulatory input from flow receptors. To assess the contribution of this single cell in turning behavior, two fine wires were glued to the surface of the brain over left and right Pedal 3. We determined that Pedal 3 activity is correlated with subsequent ipsilateral turns, preceding the lift of the foot margin and the change in orientation by a consistent interval. Both Pedal 3 cells show synchronous bursts of activity, and the firing frequency of the ipsilateral Pedal 3 increased before turns were observed to that side. Stimulation of the electrode over Pedal 3 proved sufficient to elicit an ipsilateral turn in Tritonia. PMID:15778839

  18. Necrotizing enteritis as a cause of mortality in Laysan albatross, Diomedea immutabilis, chicks on Midway Atoll, Hawaii

    USGS Publications Warehouse

    Work, T.M.; Smith, M.R.; Duncan, R.

    1998-01-01

    A necropsy survey of Laysan albatross, Diomedea immutabilis, chicks on Midway Atoll in June 1993, 1994, and 1995 revealed 54% (21/39), 67% (49/71), and 93% (15/16), respectively, to have enteritis as the most severe pathologic finding. The lesion was limited to the ileum, ceca, and large intestine. We were unable to attribute a single infectious etiology to this lesion. Many birds with enteritis also exhibited renal lesions similar to those encountered in chickens experimentally deprived of water. We propose that enteritis is a significant cause of mortality in Laysan albatross chicks on Midway and that it may be a sequela to dehydration. It is likely that the pathology of dehydration in Laysan albatross differs from that in chickens largely because of diet.

  19. Mate vocal recognition in the Scopoli's shearwater Calonectris diomedea: do females and males share the same acoustic code?

    PubMed

    Curé, Charlotte; Mathevon, Nicolas; Aubin, Thierry

    2016-07-01

    Vocal recognition is an important process allowing partners' reunion in most seabirds. Although the acoustic basis of this recognition has been explored in several species, only a few studies have experimentally tested the acoustic coding-decoding strategy used for mate identification. Here, we investigated mate recognition in the Scopoli's shearwater (Calonectris diomedea) by conducting playbacks of calls with modified acoustic features. We showed that females and males in a seabird species with a moderate vocal dimorphism are likely to share the same coding-decoding rule for vocal mate identification. Specifically, a disruption of call temporal structure prevented mate recognition in both sexes, in line with the parameters previously identified as supporting an individual signature. Modifications of spectral cues and envelope structure also impaired recognition, but at a lesser extent: almost half of the tested males and females were still able to recognise their partner. It is likely that this equal ability of female and male Scopoli's shearwaters to vocally recognise their partner could be found in other seabirds.

  20. Spatio-temporal variation in the diet of Cory's shearwater Calonectris diomedea in the Azores archipelago, northeast Atlantic

    NASA Astrophysics Data System (ADS)

    Neves, Verónica; Nolf, Dirk; Clarke, Malcolm

    2012-12-01

    The diet of Cory's shearwater Calonectris diomedea in the Azores was studied in four islands of the archipelago over four breeding seasons, using stomach flushings from 959 birds. Fish were identified from flesh, otoliths and vertebrae and cephalopods from flesh and lower beaks. The frequency of occurrence of prey taxa, and the numerical frequency of fish and cephalopods, showed marked variations both spatially, across the breeding cycle and between years. Overall, cephalopods from 37 species representing 17 families and fish from 33 species representing 18 families were identified, representing over 70 prey species and trebling what was previously known. Histioteuthidae, Ommastrephidae and Cranchiidae were the only cephalopod families present every year and represented two thirds of the cephalopods' consumption by number. Blue jack mackerel Trachurus picturatus was the most abundant prey species present in 1998 and 2002 but was absent in 1999 and 2000, representing on average 57.2% of prey by number in the years it occurred. Apart from blue jack mackerel, most fish species were present in very low numbers with the exception of Cubiceps gracilis, Scomberesox saurus and Maurolicus muellerii. Diaphus adenomus, was recorded for the first time for the Azores archipelago.

  1. Dopamine modulation of Ca(2+) dependent Cl(-) current regulates ciliary beat frequency controlling locomotion in Tritonia diomedea.

    PubMed

    Woodward, Owen M; Willows, A O Dennis

    2006-07-01

    The physiological mechanisms controlling ciliary beating remain largely unknown. Evidence exists supporting both hormonal control of ciliary beating and control via direct innervation. In the present study we investigated nervous control of cilia based locomotion in the nudibranch mollusc, Tritonia diomedea. Ciliated pedal epithelial (CPE) cells acting as locomotory effectors may be electrically excitable. To explore this possibility we characterized the cells' electrical properties, and found that CPE cells have large voltage dependent whole cell currents with two components. First, there is a fast activating outward Cl(-) current that is both voltage and Ca(2+) influx dependent (I(Cl(Ca))). I(Cl(Ca)) is sensitive to DIDS and 9-AC, and resembles currents of Ca(2+)-activated Cl(-) channels (CaCC). Ca(2+) dependence also suggests the presence of voltage-gated Ca(2+) channels; however, we were unable to detect these currents. The second current, a voltage dependent proton current (I(H)), activates very slowly and is sensitive to both Zn(2+) and changes in pH. In addition we identify a new cilio-excitatory substance in Tritonia, viz., dopamine. Dopamine, in the 10 mumol l(-1)-1 mmol l(-1) range, significantly increases ciliary beat frequency (CBF). We also found dopamine and Tritonia Pedal Peptide (TPep-NLS) selectively suppress I(Cl(Ca)) in CPE cells, demonstrating a link between CBF excitation and I(Cl(Ca)). It appears that dopamine and TPep-NLS inhibit I(Cl(Ca)) not through changing [Ca(2+)](in), but directly by an unknown mechanism. Coupling of I(Cl(Ca)) and CBF is further supported by our finding that DIDS and zero [Cl(-)](out) both increase CBF, mimicking dopamine and TPep-NLS excitation. These results suggest that dopamine and TPep-NLS act to inhibit I(Cl(Ca)), initiating and prolonging Ca(2+) influx, and activating CBF excitation. PMID:16809466

  2. Deep mRNA Sequencing of the Tritonia diomedea Brain Transcriptome Provides Access to Gene Homologues for Neuronal Excitability, Synaptic Transmission and Peptidergic Signalling

    PubMed Central

    Senatore, Adriano; Edirisinghe, Neranjan; Katz, Paul S.

    2015-01-01

    Background The sea slug Tritonia diomedea (Mollusca, Gastropoda, Nudibranchia), has a simple and highly accessible nervous system, making it useful for studying neuronal and synaptic mechanisms underlying behavior. Although many important contributions have been made using Tritonia, until now, a lack of genetic information has impeded exploration at the molecular level. Results We performed Illumina sequencing of central nervous system mRNAs from Tritonia, generating 133.1 million 100 base pair, paired-end reads. De novo reconstruction of the RNA-Seq data yielded a total of 185,546 contigs, which partitioned into 123,154 non-redundant gene clusters (unigenes). BLAST comparison with RefSeq and Swiss-Prot protein databases, as well as mRNA data from other invertebrates (gastropod molluscs: Aplysia californica, Lymnaea stagnalis and Biomphalaria glabrata; cnidarian: Nematostella vectensis) revealed that up to 76,292 unigenes in the Tritonia transcriptome have putative homologues in other databases, 18,246 of which are below a more stringent E-value cut-off of 1x10-6. In silico prediction of secreted proteins from the Tritonia transcriptome shotgun assembly (TSA) produced a database of 579 unique sequences of secreted proteins, which also exhibited markedly higher expression levels compared to other genes in the TSA. Conclusions Our efforts greatly expand the availability of gene sequences available for Tritonia diomedea. We were able to extract full length protein sequences for most queried genes, including those involved in electrical excitability, synaptic vesicle release and neurotransmission, thus confirming that the transcriptome will serve as a useful tool for probing the molecular correlates of behavior in this species. We also generated a neurosecretome database that will serve as a useful tool for probing peptidergic signalling systems in the Tritonia brain. PMID:25719197

  3. Polychlorinated Biphenyls in the Plasma and Preen Oil of Black-Footed Albatross (Diomedea nigripes) Chicks and Adults on Midway Atoll, North Pacific Ocean

    PubMed Central

    Wang, Jun; Caccamise, Sarah A. L.; Woodward, Lee Ann; Li, Qing X.

    2015-01-01

    Polychlorinated biphenyls (PCBs) are ubiquitous in the environment. Midway Atoll, located in the North Pacific Ocean, was occupied by the military during and after World War II. However, Midway Atoll has become a national wildlife refuge and home to many different seabirds today, including the black-footed albatross (Diomedea nigripes) (BFAL). The profiles and toxic equivalents (TEQ) of PCB congeners in the plasma and preen oil of BFAL chicks and adults were determined in this study. The concentrations of the total PCBs in the plasma samples of chicks and adults collected in Midway Atoll ranged from 2.3 to 223.8 (mean 80.1) and 22.8 to 504.5 (mean 158.6) ng g-1 (wet weight, ww), respectively. The TEQs ranged from 0.2 to 0.6 (mean 0.4) and 0.4 to 1.6 (mean 0.9) pg g-1 ww, respectively, in the plasma samples of chicks and adults from Midway Atoll. The major congeners in the plasma samples of chicks and adults included PCBs 31, 87, 97, 99, 118, 138, 153, and 180, accounting for 70% of the total PCBs. The concentrations of the total PCBs in the adult preen oil samples ranged from 1693 to 39404 (mean 10122) ng g-1 (ww), of which 97% were PCBs 105, 118, 128, 138, 153, 161, 172, and 183. PMID:25901941

  4. Responses to magnetic stimuli recorded in peripheral nerves in the marine nudibranch mollusk Tritonia diomedea.

    PubMed

    Pavlova, Galina A; Glantz, Raymon M; Dennis Willows, A O

    2011-10-01

    Prior behavioral and neurophysiological studies provide evidence that the nudibranch mollusk Tritonia orients to the earth's magnetic field. Earlier studies of electrophysiological responses in certain neurons of the brain to changing ambient magnetic fields suggest that although certain identified brain cells fire impulses when the ambient field is changed, these neuron somata and their central dentritic and axonal processes are themselves not primary magnetic receptors. Here, using semi-intact animal preparations from which the brain was removed, we recorded from peripheral nerve trunks. Using techniques to count spikes in individual nerves and separately also to identify, then count individual axonal spikes in extracellular records, we found both excitatory and inhibitory axonal responses elicited by changes in the direction of ambient earth strength magnetic fields. We found responses in nerves from many locations throughout the body and in axons innervating the body wall and rhinophores. Our results indicate that primary receptors for geomagnetism in Tritonia are not focally concentrated in any particular organ, but appear to be widely dispersed in the peripheral body tissues. PMID:21717186

  5. High prevalence of parental delivery of plastic debris in Cory's shearwaters (Calonectris diomedea).

    PubMed

    Rodríguez, Airam; Rodríguez, Beneharo; Nazaret Carrasco, María

    2012-10-01

    Plastic ingestion by adult Procellariiformes has been widely recorded, but few studies have evaluated intergenerational transfer. We assessed the prevalence of plastic particles, as well as their basic characteristics, in the gut content of dead Cory's shearwater fledglings stranded by light pollution on Canary Islands. Eighty-three percent of birds were affected, containing on average 8.0 plastic pieces per bird. The average plastic weight per bird was low (2.97±3.97mg) compared with other petrel species. We found no relationships between plastic loads and body condition or body size, but negative effects may be hidden or delayed. We propose to use the fledglings stranded by light pollution to carry out more precise studies to understand the potential hidden costs of plastic ingestion; and to monitor in a long-term the marine debris to develop management actions for the control of pollution at the marine environment.

  6. High prevalence of parental delivery of plastic debris in Cory's shearwaters (Calonectris diomedea).

    PubMed

    Rodríguez, Airam; Rodríguez, Beneharo; Nazaret Carrasco, María

    2012-10-01

    Plastic ingestion by adult Procellariiformes has been widely recorded, but few studies have evaluated intergenerational transfer. We assessed the prevalence of plastic particles, as well as their basic characteristics, in the gut content of dead Cory's shearwater fledglings stranded by light pollution on Canary Islands. Eighty-three percent of birds were affected, containing on average 8.0 plastic pieces per bird. The average plastic weight per bird was low (2.97±3.97mg) compared with other petrel species. We found no relationships between plastic loads and body condition or body size, but negative effects may be hidden or delayed. We propose to use the fledglings stranded by light pollution to carry out more precise studies to understand the potential hidden costs of plastic ingestion; and to monitor in a long-term the marine debris to develop management actions for the control of pollution at the marine environment. PMID:22784377

  7. Flexible foraging strategy of Cory's shearwater, Calonectris diomedea, during the chick-rearing period.

    PubMed

    Granadeiro; Nunes; Silva; Furness

    1998-11-01

    Procellariiformes are well known for their low rates of food provisioning to their slow-growing chicks. In some species, the patterns of food delivery to chicks have been deduced from changes in their weight, obtained from periodic weighings. However, the behaviour of individual parents cannot be resolved using this method. In this study, we used a periodic weighing protocol with Cory's shearwater chicks on Selvagem Grande island, in the northeast Atlantic. In addition, we used an automatic logging system to examine the attendance of individual parents. In 1997, the chicks were fed infrequently, and were in significantly poorer condition, than in other years and at other colonies. This suggests that the adults were experiencing some difficulties in finding an adequate food supply close to the colony. Under these conditions, individual parents adopted a dual provisioning strategy, making both short and long foraging trips, a previously undescribed behaviour in any northern hemisphere petrel species. Although meals delivered to chicks were larger after long trips than after short trips, the average amount of food provisioned per day spent at sea decreased with increasing trip length, and so chicks did not benefit from longer trips. This finding suggests that long trips can be used to restore the adult's body condition, presumably depleted during short trips as shown previously for some petrels and albatrosses. The adoption of this flexible foraging strategy, which differs from the uniform intervals observed in Cory's shearwaters experiencing situations of 'normal' food abundance, may represent a mechanism through which breeding birds compromise between the needs of their chicks and the maintenance of their own body condition. Copyright 1998 The Association for the Study of Animal Behaviour. PMID:9819333

  8. Marine debris ingestion by albatrosses in the southwest Atlantic Ocean.

    PubMed

    Jiménez, Sebastián; Domingo, Andrés; Brazeiro, Alejandro; Defeo, Omar; Phillips, Richard A

    2015-07-15

    Plastics and other marine debris affect wildlife through entanglement and by ingestion. We assessed the ingestion of marine debris by seven albatross species in the southwest Atlantic by analyzing stomach contents of birds killed in fisheries. Of the 128 specimens examined, including four Diomedea species (n=78) and three Thalassarche species (n=50), 21 (16.4%) contained 1-4 debris items, mainly in the ventriculus. The most common type was plastic fragments. Debris was most frequent in Diomedea species (25.6%) and, particularly, Diomedea sanfordi (38.9%) and very rare in Thalassarche species (2.0%), presumably reflecting differences in foraging behavior or distribution. Frequency of occurrence was significantly higher in male than female Diomedea albatrosses (39.3% vs. 18.0%). Although levels of accumulated debris were relatively low overall, and unlikely to result in gut blockage, associated toxins might nevertheless represent a health risk for Diomedea albatrosses, compounding the negative impact of other human activities on these threatened species. PMID:25986654

  9. Marine debris ingestion by albatrosses in the southwest Atlantic Ocean.

    PubMed

    Jiménez, Sebastián; Domingo, Andrés; Brazeiro, Alejandro; Defeo, Omar; Phillips, Richard A

    2015-07-15

    Plastics and other marine debris affect wildlife through entanglement and by ingestion. We assessed the ingestion of marine debris by seven albatross species in the southwest Atlantic by analyzing stomach contents of birds killed in fisheries. Of the 128 specimens examined, including four Diomedea species (n=78) and three Thalassarche species (n=50), 21 (16.4%) contained 1-4 debris items, mainly in the ventriculus. The most common type was plastic fragments. Debris was most frequent in Diomedea species (25.6%) and, particularly, Diomedea sanfordi (38.9%) and very rare in Thalassarche species (2.0%), presumably reflecting differences in foraging behavior or distribution. Frequency of occurrence was significantly higher in male than female Diomedea albatrosses (39.3% vs. 18.0%). Although levels of accumulated debris were relatively low overall, and unlikely to result in gut blockage, associated toxins might nevertheless represent a health risk for Diomedea albatrosses, compounding the negative impact of other human activities on these threatened species.

  10. New species of Apoloniinae (Acari: Trombiculidae) from the Laysan albatross taken in the Midway Islands and key to the species of Apoloniinae of the world

    USGS Publications Warehouse

    Goff, M.L.; Sievert, P.R.; Sileo, L.

    1989-01-01

    Womersia midwayensis Goff, Sievert and Sileo is described as a new species from specimens taken off a Laysan albatross chick, Diomedea immutabilis (L.), collected on Sand Island, Midway Islands. A key to the genera and species of larval Apoloniinae of the world is given.

  11. New records of feather lice from some seabirds in Chile.

    PubMed

    Sepúlveda, M S; Palma, R L; Ochoa-Acuña, H

    1997-04-01

    Six species of chewing lice (Phthiraptera: Menoponidae, Philopteridae) are reported from four species of seabirds collected off the coast of Chile. They are Eidmanniella pellucida, Piagetiella transitans, and Piagetiella caputincisa, from a Guanay cormorant (Phalacrocorax bougainvillii); Harrisoniella ferox collected from a black-browed albatross (Diomedea melanophrys); Ancistrona vagelli from a white-necked petrel (Pterodroma externa); and Pelmatocerandra flinti collected from a Magellan diving petrel (Pelecanoides magellani). Eidmanniella pellucida and P. transitans are reported from Chile for the first time. Piagetiella caputincisa from the Guanay cormorant may be a contaminant from a red-legged shag (Phalacrocorax gaimardi). PMID:9131581

  12. Temperature-oxygen interactions in Antarctic nudibranch egg masses.

    PubMed

    Woods, H Arthur; Moran, Amy L

    2008-03-01

    The Southern Ocean is one of the coldest, most stable marine environments on Earth and represents a unique environment for investigating metabolic consequences of low temperature. Here we test predictions of a new diffusion-reaction model of O(2) distributions in egg masses, using egg masses of the Antarctic nudibranch mollusk, Tritonia challengeriana. When warmed from -1.5 degrees to +1.5 degrees C, embryos of T. challengeriana showed large increases in O(2) consumption (Q(10) values of 9.6-30.0). Oxygen electrode measurements in intact masses showed, however, that O(2) levels were high throughout and virtually unaffected by temperature. The model suggested that both effects stemmed from very low metabolic densities in egg masses. Detailed morphological measurements of egg masses of T. challengeriana and a temperate congener, T. diomedea, revealed large differences in structure that may be related to O(2) availability. Egg masses of T. challengeriana were approximately twice as thick. However, the most dramatic effects were observed in embryos: embryos of T. challengeriana were >32 times larger (by volume) than embryos of T. diomedea. Antarctic embryos also were contained singly in large egg capsules ( approximately 500 mum diameter). Consequently, Antarctic embryos occurred at much lower densities, with very low metabolic densities. PMID:18281343

  13. Metals in albatross feathers from Midway Atoll: Influence of species, age, and nest location

    SciTech Connect

    Burger, J.; Gochfeld, M.

    2000-03-01

    In this paper the authors examine the concentrations of metals (heavy metals, mercury, lead, cadmium, chromium, manganese, tin; and metalloids, arsenic and selenium), in the down and contour (body) feathers of half-grown young albatrosses, and contour feathers of one of their parents. They collected feathers from Laysan Diomedea immutabilis and black-footed Diomedea nigripes albatrosses from Midway Atoll in the central Pacific Ocean. The authors test the null hypotheses that there is no difference in metal levels as a function of species, age, feather type, and location on the island. Using linear regression they found significant models accounting for the variation in the concentrations of mercury, lead, cadmium, selenium, chromium, and manganese (but not arsenic or tin) as a function of feather type (all metals), collection location (all metals but lead), species (selenium only), and interactions between these factors. Most metals (except mercury, arsenic, and tin) were significantly higher in down than in the contour feathers of either chicks or adults. Comparing the two species, black-footed albatross chicks had higher levels of most elements (except arsenic) in their feathers and/or down. Black-footed adults had significantly higher levels of mercury and selenium. They also collected down and feathers from Laysan albatross chicks whose nests were close to buildings, including buildings with flaking lead paint and those that had been lead-abated.

  14. Trace metals, stable isotope ratios, and trophic relations in seabirds from the North Pacific Ocean.

    PubMed

    Elliott, John E

    2005-12-01

    Trace elements including mercury, cadmium, selenium, and stable nitrogen isotope ratios (sigma15N) were measured in tissues of Pacific seabirds. Two species of albatross (Diomedea immutabilis, Diomedea nigripes), four species of shearwaters (Puffinus bulleri, Puffinus carneipes, Puffinus griseus, Puffinus tenuirostris), northern fulmar (Fulmarus glacialis), and horned puffin (Fratercula corniculata) were collected opportunistically by an experimental fishery in the North Pacific Ocean. Two species each of petrels (Oceanodroma leucorhoa, Oceanodroma furcata) and auklets (Ptychoramphus aleuticus, Cerorhinca monocerata) were collected at breeding colonies on the north coast of British Columbia, Canada. Concentrations of toxic trace metals varied considerably among the pelagic nonbreeders; highest concentrations consistently were in D. nigripes (e.g., Hg), 70-fold greater than F. corniculata (e.g., Cd), eightfold greater than P. tenuirostris (e.g., Se), and fourfold greater than F. corniculata. Most essential trace elements varied little among species, consistent with physiological regulation. Values for sigma15N correlated positively with hepatic Se (r = 0.771, p = 0.025) and negatively with Co (r = 0.817, p = 0.013). Among the four breeding species, there were significant positive associations for sigma15N in muscle and hepatic Se (r = 0.822, p = 0.002), Hg (r = 0.744, p = 0.0001), and Cd (r = 0.589, p = 0.003). Differences in time scales integrated by sigma15N versus trace metals in tissues probably reduced the apparent associations between trace-metal exposure and diet.

  15. Weights, hematology and serum chemistry of seven species of free-ranging tropical pelagic seabirds

    USGS Publications Warehouse

    Work, T.M.

    1996-01-01

    I established reference values for weight, hematology, and serum chemistry for seven species of free-ranging Hawaiian tropical pelagic seabirds comprising three orders (Procellariiformes, Pelecaniformes, Charadriiformes) and six families (Procellariidae, Phaethontidae, Diomedeidae, Sulidae, Fregatidae, and Laridae). Species examined included 84 Hawaiian darkrumped petrels (Pterodoma phaeopygia), 90 wedge-tailed shearwaters (Puffinus pacificus), 151 Laysan albatrosses (Diomedea immutabilis), 69 red-footed boobies (Sula sula), 154 red-tailed tropicbirds (Phaeton rubricauda), 90 great frigatebirds (Fregata minor), and 72 sooty terns (Sterna fuscata). Hematocrit, total plasma solids, total and differential white cell counts, serum glucose, calcium, phosphorus, uric acid, total protein, albumin, globulin, aspartate aminotransferase and creatinine phosphokinase were analyzed. Among and within species, hematology and chemistry values varied with age, sex, season, and island of collection. Despite this variation, order-wide trends were observed.

  16. Regional differences in plastic ingestion among Southern Ocean fur seals and albatrosses.

    PubMed

    Ryan, Peter G; de Bruyn, P J Nico; Bester, Marthán N

    2016-03-15

    We provide data on regional differences in plastic ingestion for two Southern Ocean top predators: Arctocephalus fur seals and albatrosses (Diomedeidae). Fur seals breeding on Macquarie Island in the 1990s excreted small (mainly 2-5 mm) plastic fragments, probably derived secondarily from myctophid fish. No plastic was found in the scats of these seals breeding on three islands in the southwest Indian and central South Atlantic Oceans, despite myctophids dominating their diets at these locations. Compared to recent reports of plastic ingestion by albatrosses off the east coast of South America, we confirm that plastic is seldom found in the stomachs of Thalassarche albatrosses off South Africa, but found no Diomedea albatrosses to contain plastic, compared to 26% off South America. The reasons for such regional differences are unclear, but emphasize the importance of reporting negative as well as positive records of plastic ingestion by marine biota.

  17. Paint chip poisoning of Laysan albatross at Midway Atoll (Pacific Ocean)

    USGS Publications Warehouse

    Sileo, L.; Fefer, S.I.

    1987-01-01

    Epizootic mortality occurred in Laysan albatross (Diomedea immutabilis) fledgings at Midway Atoll in 1983. Heavy metal toxicity from ingestion of weathered paint chips was one of the causes. Sick albatrosses were unable to retract their wings, causing a 'droop-wing' appearance. Five normal and 12 droop-winged fledglings were captured, killed, and examined. Paint chips found in the proventriculus of the affected fledglings contained up to 144,000 ppm lead. Blood, liver, and kidney concentrations of lead in affected birds were higher than in normal fledglings, and acid-fast intranuclear inclusion bodies were present in the kidneys. Degenerative lesions were present in the myelin of some brachial nerves. Weathered paint samples collected from 12 buildings contained up to 247,250 ppm lead and 101 ppm mercury. Lead poisoning was diagnosed in 10 of the droop-winged albatrosses and was one of the causes of morbidity. Mercury toxicosis and plastic impaction were other possible causes.

  18. Causes of mortality of albatross chicks at Midway Atoll

    USGS Publications Warehouse

    Sileo, L.; Sievert, P.R.; Samuel, M.D.

    1990-01-01

    As part of an investigation of the effect of plastic ingestion on seabirds in Hawaii, we necropsied the carcasses of 137 Laysan albatross (Diomedea immutabilis) chicks from Midway Atoll in the Pacific Ocean during the summer of 1987. Selected tissues were collected for microbiological, parasitological, toxicological or histopathological examinations. Dehydration was the most common cause of death. Lead poisoning, trauma, emaciation (starvation) and trombidiosis were other causes of death; nonfatal nocardiosis and avian pox also were present. There was no evidence that ingested plastic caused mechanical lesions or mortality in 1987, but most of the chicks had considerably less plastic in them than chicks from earlier years. Human activity (lead poisoning and vehicular trauma) caused mortality at Midway Atoll and represented additive mortality for pre-fledgling albatrosses.

  19. Regional differences in plastic ingestion among Southern Ocean fur seals and albatrosses.

    PubMed

    Ryan, Peter G; de Bruyn, P J Nico; Bester, Marthán N

    2016-03-15

    We provide data on regional differences in plastic ingestion for two Southern Ocean top predators: Arctocephalus fur seals and albatrosses (Diomedeidae). Fur seals breeding on Macquarie Island in the 1990s excreted small (mainly 2-5 mm) plastic fragments, probably derived secondarily from myctophid fish. No plastic was found in the scats of these seals breeding on three islands in the southwest Indian and central South Atlantic Oceans, despite myctophids dominating their diets at these locations. Compared to recent reports of plastic ingestion by albatrosses off the east coast of South America, we confirm that plastic is seldom found in the stomachs of Thalassarche albatrosses off South Africa, but found no Diomedea albatrosses to contain plastic, compared to 26% off South America. The reasons for such regional differences are unclear, but emphasize the importance of reporting negative as well as positive records of plastic ingestion by marine biota. PMID:26827096

  20. The Lévy flight foraging hypothesis in a pelagic seabird.

    PubMed

    Focardi, Stefano; Cecere, Jacopo G

    2014-03-01

    Lévy flight foraging represents an innovative paradigm for the analysis of animal random search by including models of heavy-tailed distribution of move length, which complements the correlated random walk paradigm that is founded on Brownian walks. Theory shows that the efficiency of the different foraging tactics is a function of prey abundance and dynamics with Lévy flight being especially efficient in poor prey fields. Lévy flights have been controversial in some quarters, because they previously have been wrongly ascribed to many species through the employment of inappropriate statistical techniques and by misunderstanding movement pattern data. More recent studies using state-of-the-art statistical tools have, however, provided seemingly compelling evidence for Lévy flights. In this study, we employ these maximum-likelihood methods and their Bayesian equivalents by analysing both turning angles and move length distributions. We tested, for compliance with Lévy flight foraging, a set of 77 independent foraging trajectories of Cory's shearwaters Calonectris diomedea diomedea. Birds were tagged with high-resolution GPS loggers in two Mediterranean colonies (Linosa and Tremiti) during both incubation and chick rearing. We found that the behaviour of six birds was fitted by a correlated random walk; the movement of 32 birds was better represented by adaptive correlated random walks by switching from intensive to extensive searches; and the trajectories of 36 birds were fitted by a Lévy flight pattern of movement. The probability of performing Lévy flights was higher for trips during chick provisioning when shearwaters were forced to forage in suboptimal areas. This study supports Lévy flight foraging as an appropriate framework to analyse search tactics in this pelagic bird species and highlights that the adoption of a given search strategy is a function of biological and ecological constraints.

  1. Metal levels in feathers of 12 species of seabirds from midway atoll in the northern Pacific Ocean.

    PubMed

    Burger, J; Gochfeld, M

    2000-07-20

    Seabirds are excellent subjects for examination of heavy metals because they are long-lived, feed at different distances from land, and exhibit different trophic levels. In this paper we compare the levels of lead, cadmium, mercury arsenic, chromium, manganese, selenium, and tin in the feathers of birds nesting on Midway Atoll in the northern Pacific Ocean. We test the null hypothesis that there are no interspecific differences in the levels of metals in the feathers of the adult black-footed albatross (Diomedea nigripes), Laysan albatross (Diomedea immutabilis), red-footed booby (Sula sula), great frigatebird (Fregata minor), Bonin petrel (Pterodroma hypoleuca), Christmas shearwater (Puffinus nativitatis), red-tailed tropicbird (Phaethon rubricauda), wedge-tailed shearwater (Puffinus pacificus), brown noddy (Anous stolidus), sooty tern (Stema fuscata), grey-backed tern (Stema lunata), and white tern (Gygis alba), and young of some of these species. There were interspecific differences in the levels of all metals for adults. Christmas shearwater had the highest levels of lead, cadmium, selenium and manganese, but the second lowest levels of mercury. In general, metal levels were the lowest in the smallest species (white tern), but were not the highest in the largest species (black-footed albatross), except for manganese, arsenic and mercury. There was a high variance in metal levels among adults for some species, but not for others. White tern adults were variable for lead, while Christmas shearwaters were variable for lead and cadmium. Compared to the means for metals in other birds generally (after Burger, 1993), Christmas shearwaters had higher levels of lead, white terns, brown noddy, Christmas shearwater, frigatebirds and Laysan albatrosses had higher levels of cadmium, and bonin petrel, wedge-tailed shearwater, tropicbirds, frigatebirds, red-footed boobies, and both albatrosses had higher levels of mercury. Whereas the means for lead and cadmium were below

  2. Hypoxia Tolerance and Metabolic Suppression in Oxygen Minimum Zone Euphausiids: Implications for Ocean Deoxygenation and Biogeochemical Cycles.

    PubMed

    Seibel, Brad A; Schneider, Jillian L; Kaartvedt, Stein; Wishner, Karen F; Daly, Kendra L

    2016-10-01

    The effects of regional variations in oxygen and temperature levels with depth were assessed for the metabolism and hypoxia tolerance of dominant euphausiid species. The physiological strategies employed by these species facilitate prediction of changing vertical distributions with expanding oxygen minimum zones and inform estimates of the contribution of vertically migrating species to biogeochemical cycles. The migrating species from the Eastern Tropical Pacific (ETP), Euphausia eximia and Nematoscelis gracilis, tolerate a Partial Pressure (PO2) of 0.8 kPa at 10 °C (∼15 µM O2) for at least 12 h without mortality, while the California Current species, Nematoscelis difficilis, is incapable of surviving even 2.4 kPa PO2 (∼32 µM O2) for more than 3 h at that temperature. Euphausia diomedeae from the Red Sea migrates into an intermediate oxygen minimum zone, but one in which the temperature at depth remains near 22 °C. Euphausia diomedeae survived 1.6 kPa PO2 (∼22 µM O2) at 22 °C for the duration of six hour respiration experiments. Critical oxygen partial pressures were estimated for each species, and, for E. eximia, measured via oxygen consumption (2.1 kPa, 10 °C, n = 2) and lactate accumulation (1.1 kPa, 10 °C). A primary mechanism facilitating low oxygen tolerance is an ability to dramatically reduce energy expenditure during daytime forays into low oxygen waters. The ETP and Red Sea species reduced aerobic metabolism by more than 50% during exposure to hypoxia. Anaerobic glycolytic energy production, as indicated by whole-animal lactate accumulation, contributed only modestly to the energy deficit. Thus, the total metabolic rate was suppressed by ∼49-64%. Metabolic suppression during diel migrations to depth reduces the metabolic contribution of these species to vertical carbon and nitrogen flux (i.e., the biological pump) by an equivalent amount. Growing evidence suggests that metabolic suppression is a widespread strategy among migrating

  3. Hypoxia Tolerance and Metabolic Suppression in Oxygen Minimum Zone Euphausiids: Implications for Ocean Deoxygenation and Biogeochemical Cycles.

    PubMed

    Seibel, Brad A; Schneider, Jillian L; Kaartvedt, Stein; Wishner, Karen F; Daly, Kendra L

    2016-10-01

    The effects of regional variations in oxygen and temperature levels with depth were assessed for the metabolism and hypoxia tolerance of dominant euphausiid species. The physiological strategies employed by these species facilitate prediction of changing vertical distributions with expanding oxygen minimum zones and inform estimates of the contribution of vertically migrating species to biogeochemical cycles. The migrating species from the Eastern Tropical Pacific (ETP), Euphausia eximia and Nematoscelis gracilis, tolerate a Partial Pressure (PO2) of 0.8 kPa at 10 °C (∼15 µM O2) for at least 12 h without mortality, while the California Current species, Nematoscelis difficilis, is incapable of surviving even 2.4 kPa PO2 (∼32 µM O2) for more than 3 h at that temperature. Euphausia diomedeae from the Red Sea migrates into an intermediate oxygen minimum zone, but one in which the temperature at depth remains near 22 °C. Euphausia diomedeae survived 1.6 kPa PO2 (∼22 µM O2) at 22 °C for the duration of six hour respiration experiments. Critical oxygen partial pressures were estimated for each species, and, for E. eximia, measured via oxygen consumption (2.1 kPa, 10 °C, n = 2) and lactate accumulation (1.1 kPa, 10 °C). A primary mechanism facilitating low oxygen tolerance is an ability to dramatically reduce energy expenditure during daytime forays into low oxygen waters. The ETP and Red Sea species reduced aerobic metabolism by more than 50% during exposure to hypoxia. Anaerobic glycolytic energy production, as indicated by whole-animal lactate accumulation, contributed only modestly to the energy deficit. Thus, the total metabolic rate was suppressed by ∼49-64%. Metabolic suppression during diel migrations to depth reduces the metabolic contribution of these species to vertical carbon and nitrogen flux (i.e., the biological pump) by an equivalent amount. Growing evidence suggests that metabolic suppression is a widespread strategy among migrating

  4. Metal levels in feathers of 12 species of seabirds from midway atoll in the northern Pacific Ocean.

    PubMed

    Burger, J; Gochfeld, M

    2000-07-20

    Seabirds are excellent subjects for examination of heavy metals because they are long-lived, feed at different distances from land, and exhibit different trophic levels. In this paper we compare the levels of lead, cadmium, mercury arsenic, chromium, manganese, selenium, and tin in the feathers of birds nesting on Midway Atoll in the northern Pacific Ocean. We test the null hypothesis that there are no interspecific differences in the levels of metals in the feathers of the adult black-footed albatross (Diomedea nigripes), Laysan albatross (Diomedea immutabilis), red-footed booby (Sula sula), great frigatebird (Fregata minor), Bonin petrel (Pterodroma hypoleuca), Christmas shearwater (Puffinus nativitatis), red-tailed tropicbird (Phaethon rubricauda), wedge-tailed shearwater (Puffinus pacificus), brown noddy (Anous stolidus), sooty tern (Stema fuscata), grey-backed tern (Stema lunata), and white tern (Gygis alba), and young of some of these species. There were interspecific differences in the levels of all metals for adults. Christmas shearwater had the highest levels of lead, cadmium, selenium and manganese, but the second lowest levels of mercury. In general, metal levels were the lowest in the smallest species (white tern), but were not the highest in the largest species (black-footed albatross), except for manganese, arsenic and mercury. There was a high variance in metal levels among adults for some species, but not for others. White tern adults were variable for lead, while Christmas shearwaters were variable for lead and cadmium. Compared to the means for metals in other birds generally (after Burger, 1993), Christmas shearwaters had higher levels of lead, white terns, brown noddy, Christmas shearwater, frigatebirds and Laysan albatrosses had higher levels of cadmium, and bonin petrel, wedge-tailed shearwater, tropicbirds, frigatebirds, red-footed boobies, and both albatrosses had higher levels of mercury. Whereas the means for lead and cadmium were below

  5. Hidden synaptic differences in a neural circuit underlie differential behavioral susceptibility to a neural injury

    PubMed Central

    Sakurai, Akira; Tamvacakis, Arianna N; Katz, Paul S

    2014-01-01

    Individuals vary in their responses to stroke and trauma, hampering predictions of outcomes. One reason might be that neural circuits contain hidden variability that becomes relevant only when those individuals are challenged by injury. We found that in the mollusc, Tritonia diomedea, subtle differences between animals within the neural circuit underlying swimming behavior had no behavioral relevance under normal conditions but caused differential vulnerability of the behavior to a particular brain lesion. The extent of motor impairment correlated with the site of spike initiation in a specific neuron in the neural circuit, which was determined by the strength of an inhibitory synapse onto this neuron. Artificially increasing or decreasing this inhibitory synaptic conductance with dynamic clamp correspondingly altered the extent of motor impairment by the lesion without affecting normal operation. The results suggest that neural circuit differences could serve as hidden phenotypes for predicting the behavioral outcome of neural damage. DOI: http://dx.doi.org/10.7554/eLife.02598.001 PMID:24920390

  6. Comparative mapping of serotonin-immunoreactive neurons in the central nervous systems of nudibranch molluscs.

    PubMed

    Newcomb, James M; Fickbohm, David J; Katz, Paul S

    2006-11-20

    The serotonergic systems in nudibranch molluscs were compared by mapping the locations of serotonin-immunoreactive (5-HT-ir) neurons in 11 species representing all four suborders of the nudibranch clade: Dendronotoidea (Tritonia diomedea, Tochuina tetraquetra, Dendronotus iris, Dendronotus frondosus, and Melibe leonina), Aeolidoidea (Hermissenda crassicornis and Flabellina trophina), Arminoidea (Dirona albolineata, Janolus fuscus, and Armina californica), and Doridoidea (Triopha catalinae). A nomenclature is proposed to standardize reports of cell location in species with differing brain morphologies. Certain patterns of 5-HT immunoreactivity were found to be consistent for all species, such as the presence of 5-HT-ir neurons in the pedal and cerebral ganglia. Also, particular clusters of 5-HT-ir neurons in the anterior and posterior regions of the dorsal surface of the cerebral ganglion were always present. However, there were interspecies differences in the number of 5-HT-ir neurons in each cluster, and some clusters even exhibited strong intraspecies variability that was only weakly correlated with brain size. Phylogenetic analysis suggests that the presence of particular classes of 5-HT-ir neurons exhibits a great deal of homoplasy. The conserved features of the nudibranch serotonergic system presumably represent the shared ancestral structure, whereas the derived characters suggest substantial independent evolutionary changes in the number and presence of serotonergic neurons. Although a number of studies have demonstrated phylogenetic variability of peptidergic systems, this study suggests that serotonergic systems may also exhibit a high degree of homoplasy in some groups of organisms. PMID:16998939

  7. Homologues of serotonergic central pattern generator neurons in related nudibranch molluscs with divergent behaviors.

    PubMed

    Newcomb, James M; Katz, Paul S

    2007-04-01

    Homologues of a neuron that contributes to a species-specific behavior were identified and characterized in species lacking that behavior. The nudibranch Tritonia diomedea swims by flexing its body dorsally and ventrally. The dorsal swim interneurons (DSIs) are components of the central pattern generator (CPG) underlying this rhythmic motor pattern and also activate crawling. Homologues of the DSIs were identified in six nudibranchs that do not exhibit dorsal-ventral swimming: Tochuina tetraquetra, Melibe leonina, Dendronotus iris, D. frondosus, Armina californica, and Triopha catalinae. Homology was based upon shared features that distinguish the DSIs from all other neurons: (1) serotonin immunoreactivity, (2) location in the Cerebral serotonergic posterior (CeSP) cluster, and (3) axon projection to the contralateral pedal ganglion. The DSI homologues, named CeSP-A neurons, share additional features with the DSIs: irregular basal firing, synchronous inputs, electrical coupling, and reciprocal inhibition. Unlike the DSIs, the CeSP-A neurons were not rhythmically active in response to nerve stimulation. The CeSP-A neurons in Tochuina and Triopha also excited homologues of the Tritonia Pd5 neuron, a crawling efferent. Thus, the CeSP-A neurons and the DSIs may be part of a conserved network related to crawling that may have been co-opted into a rhythmic swim CPG in Tritonia. PMID:17180703

  8. Comparative study of TPep-like immunoreactive neurons in the central nervous system of nudibranch molluscs.

    PubMed

    Baltzley, Michael J; Lohmann, Kenneth J

    2008-11-01

    In the sea slug Tritonia diomedea, mucociliary crawling is controlled partly by two pairs of bilaterally symmetrical neurons located in the pedal ganglia. These neurons, known as the Pedal 5 and Pedal 6 cells, produce a class of neuropeptides called TPeps. Using immunohistochemistry we identified TPep-like immunoreactive (TPep-LIR) neurons in diverse nudibranch species. All species examined had 2-7 large, TPep-LIR cells located in each pedal ganglion. The absolute size of the largest TPep-LIR neuron was correlated with foot size. Species with a bigger foot size tended to have larger TPep-LIR cells. However, the number of cells in a given species was not correlated with the size of the adult foot. The presence of large, TPep-LIR cells across the nudibranchs suggests that part of the neural circuitry controlling mucociliary locomotion has been conserved, although the size and number of cells is variable across species. We conclude that the motor circuit underlying crawling might adapt to changes in foot size by changing the size of motor neurons in the circuit, but that changes in cell number are not directly related to foot size. PMID:18815443

  9. Different functions for homologous serotonergic interneurons and serotonin in species-specific rhythmic behaviours.

    PubMed

    Newcomb, James M; Katz, Paul S

    2009-01-01

    Closely related species can exhibit different behaviours despite homologous neural substrates. The nudibranch molluscs Tritonia diomedea and Melibe leonina swim differently, yet their nervous systems contain homologous serotonergic neurons. In Tritonia, the dorsal swim interneurons (DSIs) are members of the swim central pattern generator (CPG) and their neurotransmitter serotonin is both necessary and sufficient to elicit a swim motor pattern. Here it is shown that the DSI homologues in Melibe, the cerebral serotonergic posterior-A neurons (CeSP-As), are extrinsic to the swim CPG, and that neither the CeSP-As nor their neurotransmitter serotonin is necessary for swim motor pattern initiation, which occurred when the CeSP-As were inactive. Furthermore, the serotonin antagonist methysergide blocked the effects of both the serotonin and CeSP-As but did not prevent the production of a swim motor pattern. However, the CeSP-As and serotonin could influence the Melibe swim circuit; depolarization of a cerebral serotonergic posterior-A was sufficient to initiate a swim motor pattern and hyperpolarization of a CeSP-A temporarily halted an ongoing swim motor pattern. Serotonin itself was sufficient to initiate a swim motor pattern or make an ongoing swim motor pattern more regular. Thus, evolution of species-specific behaviour involved alterations in the functions of identified homologous neurons and their neurotransmitter. PMID:18782747

  10. Do seabirds differ from other migrants in their travel arrangements? On route strategies of Cory's shearwater during its trans-equatorial journey.

    PubMed

    Dias, Maria P; Granadeiro, José P; Catry, Paulo

    2012-01-01

    Long-distance migrants have developed diverse strategies to deal with the challenges imposed by their annual journeys. These are relatively well studied in some avian groups, such as passerines, shorebirds and raptors. In contrast, few studies have addressed the migratory behaviour of pelagic birds in the light of current theories of optimal migration. Using a dataset of 100 complete migratory tracks gathered along four years, we performed a detailed study on the migratory strategy of a pelagic trans-equatorial migrant, the Cory's shearwater Calonectris diomedea. We analysed daily routines, stopover ecology and travel speed, as well as the influence of the moon on several behavioural patterns. Cory's shearwaters adopted a "fly-and-forage" strategy when migrating, similarly to what has been observed in some raptors. However, by flying by dynamic soaring, shearwaters attained high overall migration speeds, and were able to travel thousands of kilometres without making major stopovers and, apparently, without a noticeable pre-migratory fattening period. Other major findings of this study include the ability to adapt daily schedules when crossing major ecological barriers, and the constant adjustment of migration speed implying higher rates of travel in the pre-breeding movement, with a final sprint to the nesting colony. The present study also highlights a preference of Cory's shearwaters for starting travel at twilight and documents a strong relationship between their migratory activity and the moon phase.

  11. Evidence for Sex-Segregated Ocean Distributions of First-Winter Wandering Albatrosses at Crozet Islands

    PubMed Central

    Åkesson, Susanne; Weimerskirch, Henri

    2014-01-01

    The highly mobile wandering albatrosses (Diomedea exulans) are adapted to navigate the extreme environment of the Southern Ocean and return to isolated islands to breed. Each year they cover several hundreds of thousands of kilometers during travels across the sea. Little is known about the dispersal flights and migration of young albatrosses. We tracked, by satellite telemetry, the departure dispersal of 13 juvenile wandering albatrosses from the Crozet Islands and compared them with tracks of 7 unrelated adults during the interbreeding season. We used the satellite tracks to identify different behavioural steps of the inherited migration program used by juvenile wandering albatrosses during their first solo-migration. Our results show that the juvenile wandering albatrosses from Crozet Islands moved to sex-specific foraging zones of the ocean using at departures selectively the wind. The results suggest that the inherited migration program used by the juvenile wandering albatrosses encode several distinct steps, based on inherited preferred departure routes, differences in migration distance between sexes, and selective use of winds. During long transportation flights the albatrosses were influenced by winds and both adult and juveniles followed approximate loxodrome (rhumbline) routes coinciding with the foraging zone and the specific latitudes of their destination areas. During the long segments of transportation flights across open seas the juveniles selected routes at more northerly latitudes than adults. PMID:24586254

  12. Different Means to the Same End: Long-Distance Migrant Seabirds from Two Colonies Differ in Behaviour, Despite Common Wintering Grounds

    PubMed Central

    Catry, Paulo; Dias, Maria P.; Phillips, Richard A.; Granadeiro, José P.

    2011-01-01

    Although seabirds that are trans-equatorial migrants show apparently broad overlap among populations in the non-breeding season, such large-scale pattern may conceal subtle but nevertheless key differences in migratory behaviour. These specializations could reflect adaptation to different environments during the breeding season, carry-over effects from the breeding to the nonbreeding period, or asymmetries in competitive ability of birds of different origin. We compared the migratory and wintering behaviour of Cory's shearwaters Calonectris diomedea nesting in Berlengas and in the Selvagens, two colonies in contrasting oceanographic environments, separated by ca. 1200 km. Although no differences were found in winter distribution, there was a marked divergence in timing, route and the use of staging areas during the postbreeding (autumn) migration. Birds from Berlengas typically travelled to oceanic waters in the North Atlantic for an extended stopover, whereas those from Selvagens rarely did so. In the South Atlantic, birds from Selvagens spent more time in flight, perhaps because they had higher energy and nutrient requirements for feather replacement compared to birds from Berlengas, which moult more flight feathers during breeding. Stable isotope analyses of feathers suggested that this variation in activity patterns was unrelated to trophic ecology. Differences in migration routes and stopovers may expose populations to distinct threats, and should be taken into consideration when defining units for conservation purposes and developing appropriate management strategies. PMID:22022513

  13. Extreme variation in migration strategies between and within wandering albatross populations during their sabbatical year, and their fitness consequences.

    PubMed

    Weimerskirch, Henri; Delord, Karine; Guitteaud, Audrey; Phillips, Richard A; Pinet, Patrick

    2015-01-01

    Migratory behavior, routes and zones used during the non-breeding season are assumed to have been selected to maximize fitness, and can lead to genetic differentiation. Yet, here we show that migration strategies differ markedly between and within two genetically similar populations of wandering albatross Diomedea exulans from the Crozet and Kerguelen archipelagos in the Indian Ocean. Wandering albatrosses usually breed biennially if successful, and during the sabbatical year, all birds from Kerguelen migrate to the Pacific Ocean, whereas most from Crozet are sedentary. Instead of taking the shortest routes, which would involve a return against headwinds, migratory birds fly with the westerly winds, requiring detours of 10,000 s km. In total, migrants circumnavigate Antarctica 2 to 3 times, covering more than 120,000 km in a single sabbatical year. Our results indicate strong links between migratory behavior and fitness; all birds from Kerguelen breed biennially, whereas a significant proportion of those from Crozet, especially females, are sedentary and breed in consecutive calendar years. To breed annually, these females temporarily change mate, but return to their original partner in the following year. This extreme variation in migratory behavior has important consequences in term of life history evolution and susceptibility to climate change and fisheries. PMID:25747757

  14. Wandering albatrosses document latitudinal variations in the transfer of persistent organic pollutants and mercury to Southern Ocean predators.

    PubMed

    Carravieri, Alice; Bustamante, Paco; Tartu, Sabrina; Meillère, Alizée; Labadie, Pierre; Budzinski, Hélène; Peluhet, Laurent; Barbraud, Christophe; Weimerskirch, Henri; Chastel, Olivier; Cherel, Yves

    2014-12-16

    Top marine predators are effective tools to monitor bioaccumulative contaminants in remote oceanic environments. Here, we used the wide-ranging wandering albatross Diomedea exulans to investigate potential geographical variations of contaminant transfer to predators in the Southern Ocean. Blood concentrations of 19 persistent organic pollutants and 14 trace elements were measured in a large number of individuals (N = 180) of known age, sex and breeding status from the subantarctic Crozet Islands. Wandering albatrosses were exposed to a wide range of contaminants, with notably high blood mercury concentrations. Contaminant burden was markedly influenced by latitudinal foraging habitats (inferred from blood δ(13)C values), with individuals feeding in warmer subtropical waters having lower concentrations of pesticides, but higher concentrations of mercury, than those feeding in colder subantarctic waters. Sexual differences in contaminant burden seemed to be driven by gender specialization in feeding habitats, rather than physiological characteristics, with females foraging further north than males. Other individual traits, such as adult age and reproductive status, had little effect on blood contaminant concentrations. Our study provides further evidence of the critical role of global distillation on organic contaminant exposure to Southern Ocean avian predators. In addition, we document an unexpected high transfer of mercury to predators in subtropical waters, which merits further investigation. PMID:25423551

  15. Scale-dependent hierarchical adjustments of movement patterns in a long-range foraging seabird.

    PubMed Central

    Fritz, Hervé; Said, Sonia; Weimerskirch, Henri

    2003-01-01

    Foraging animals are expected to adjust their path according to the hierarchical spatial distribution of food resources and environmental factors. Studying such behaviour requires methods that allow for the detection of changes in pathways' characteristics across scales, i.e. a definition of scale boundaries and techniques to continuously monitor the precise movement of the animal over a sufficiently long period. We used a recently developed application of fractals, the changes in fractal dimension within a path and applied it to foraging trips over scales ranging across five orders of magnitude (10 m to 1000 km), using locations of wandering albatrosses (Diomedea exulans) recorded at 1 s intervals with a miniaturized global positioning system. Remarkably, all animals consistently showed the same pattern: the use of three scale-dependent nested domains where they adjust tortuosity to different environmental and behavioural constraints. At a small scale (ca. 100 m) they use a zigzag movement as they continuously adjust for optimal use of wind; at a medium scale (1-10 km), the movement shows changes in tortuosity consistent with food-searching behaviour; and at a large scale (greater than 10 km) the movement corresponds to commuting between patches and is probably influenced by large-scale weather systems. Our results demonstrate the possibility of identifying the hierarchical spatial scales at which long-ranging animals adjust their foraging behaviour, even in featureless environments such as oceans, and hence how to relate their movement patterns to environmental factors using an objective mathematical approach. PMID:12816652

  16. Ocean surface winds drive dynamics of transoceanic aerial movements.

    PubMed

    Felicísimo, Angel M; Muñoz, Jesús; González-Solis, Jacob

    2008-08-13

    Global wind patterns influence dispersal and migration processes of aerial organisms, propagules and particles, which ultimately could determine the dynamics of colonizations, invasions or spread of pathogens. However, studying how wind-mediated movements actually happen has been hampered so far by the lack of high resolution global wind data as well as the impossibility to track aerial movements. Using concurrent data on winds and actual pathways of a tracked seabird, here we show that oceanic winds define spatiotemporal pathways and barriers for large-scale aerial movements. We obtained wind data from NASA SeaWinds scatterometer to calculate wind cost (impedance) models reflecting the resistance to the aerial movement near the ocean surface. We also tracked the movements of a model organism, the Cory's shearwater (Calonectris diomedea), a pelagic bird known to perform long distance migrations. Cost models revealed that distant areas can be connected through "wind highways" that do not match the shortest great circle routes. Bird routes closely followed the low-cost "wind-highways" linking breeding and wintering areas. In addition, we found that a potential barrier, the near surface westerlies in the Atlantic sector of the Intertropical Convergence Zone (ITCZ), temporally hindered meridional trans-equatorial movements. Once the westerlies vanished, birds crossed the ITCZ to their winter quarters. This study provides a novel approach to investigate wind-mediated movements in oceanic environments and shows that large-scale migration and dispersal processes over the oceans can be largely driven by spatiotemporal wind patterns.

  17. Comparative study of TPep-like immunoreactive neurons in the central nervous system of nudibranch molluscs.

    PubMed

    Baltzley, Michael J; Lohmann, Kenneth J

    2008-11-01

    In the sea slug Tritonia diomedea, mucociliary crawling is controlled partly by two pairs of bilaterally symmetrical neurons located in the pedal ganglia. These neurons, known as the Pedal 5 and Pedal 6 cells, produce a class of neuropeptides called TPeps. Using immunohistochemistry we identified TPep-like immunoreactive (TPep-LIR) neurons in diverse nudibranch species. All species examined had 2-7 large, TPep-LIR cells located in each pedal ganglion. The absolute size of the largest TPep-LIR neuron was correlated with foot size. Species with a bigger foot size tended to have larger TPep-LIR cells. However, the number of cells in a given species was not correlated with the size of the adult foot. The presence of large, TPep-LIR cells across the nudibranchs suggests that part of the neural circuitry controlling mucociliary locomotion has been conserved, although the size and number of cells is variable across species. We conclude that the motor circuit underlying crawling might adapt to changes in foot size by changing the size of motor neurons in the circuit, but that changes in cell number are not directly related to foot size.

  18. Pelagic seabird flight patterns are consistent with a reliance on olfactory maps for oceanic navigation

    PubMed Central

    Reynolds, Andrew M.; Cecere, Jacopo G.; Paiva, Vitor H.; Ramos, Jaime A.; Focardi, Stefano

    2015-01-01

    Homing studies have provided tantalizing evidence that the remarkable ability of shearwaters (Procellariiformes) to pinpoint their breeding colony after crossing vast expanses of featureless open ocean can be attributed to their assembling cognitive maps of wind-borne odours but crucially, it has not been tested whether olfactory cues are actually used as a system for navigation. Obtaining statistically important samples of wild birds for use in experimental approaches is, however, impossible because of invasive sensory manipulation. Using an innovative non-invasive approach, we provide strong evidence that shearwaters rely on olfactory cues for oceanic navigation. We tested for compliance with olfactory-cued navigation in the flight patterns of 210 shearwaters of three species (Cory's shearwaters, Calonectris borealis, North Atlantic Ocean, Scopoli's shearwaters, C. diomedea Mediterranean Sea, and Cape Verde shearwaters, C. edwardsii, Central Atlantic Ocean) tagged with high-resolution GPS loggers during both incubation and chick rearing. We found that most (69%) birds displayed exponentially truncated scale-free (Lévy-flight like) displacements, which we show are consistent with olfactory-cued navigation in the presence of atmospheric turbulence. Our analysis provides the strongest evidence yet for cognitive odour map navigation in wild birds. Thus, we may reconcile two highly disputed questions in movement ecology, by mechanistically connecting Lévy displacements and olfactory navigation. Our approach can be applied to any species which can be tracked at sufficient spatial resolution, using a GPS logger. PMID:26136443

  19. Total PCBs, TCDD-EQs in eggs: Reproductive hazards to north Pacific albatrosses

    SciTech Connect

    Ludwig, J.P.; Auman, H.J.; Summer, C.L.; Giesy, J.P.; Sanderson, J.T.; DeDoes, J.M.; Verbrugge, D.A.; Jones, P.

    1995-12-31

    Freshly laid eggs of Laysan and black-footed Albatrosses (Diomedea immutabilis and D. nigripes) were collected at Midway Atoll 1992 through 1994 and subsequently analyzed for chlorinated contaminants including OC pesticides, PCBs, dioxins and furans. TCDD-EQs in eggs were calculated from congener-specific data. Total PCBs ranged from 1.1 to 3.8 mglkg ww. Calculated TCDD-EQs ranged from 52--124 pg/g. A substantial portion (30--35%) of the TCDD-EQs in eggs were owing to dioxins and furans, and the balance to PCBs. PCBs in albatross eggs were much less potent than PCBs from waterbirds` eggs of the Great Lakes and other continental inland waters. Hazard indices based on calculated TCDD-EQs suggested that Laysan eggs were at the LOAEL for embryonic effects, but black-footed eggs were well above avian LOAELS. Egg death during natural incubation was 2--3% greater in black-footed than Laysan nests, and 5% fewer black-footed albatross chicks were fledged in 1994. A low incidence of deformities in hatchlings was noted in 1994 and 1995. Crossed-bill hatchlings were not reported in these populations until the late 1970s in spite of intensive studies 1957--1972, but occurred at rates of 1 in 14,000 hatchlings, and 1 in 300 dead eggs 1993--1995. Reproductive effects owing to contaminant exposures in these most pelagic seabirds are confirmed.

  20. GPS tracking for mapping seabird mortality induced by light pollution.

    PubMed

    Rodríguez, Airam; Rodríguez, Beneharo; Negro, Juan J

    2015-01-01

    Light pollution and its consequences on ecosystems are increasing worldwide. Knowledge on the threshold levels of light pollution at which significant ecological impacts emerge and the size of dark refuges to maintain natural nocturnal processes is crucial to mitigate its negative consequences. Seabird fledglings are attracted by artificial lights when they leave their nest at night, causing high mortality. We used GPS data-loggers to track the flights of Cory's shearwater Calonectris diomedea fledglings from nest-burrows to ground, and to evaluate the light pollution levels of overflown areas on Tenerife, Canary Islands, using nocturnal, high-resolution satellite imagery. Birds were grounded at locations closer than 16 km from colonies in their maiden flights, and 50% were rescued within a 3 km radius from the nest-site. Most birds left the nests in the first three hours after sunset. Rescue locations showed radiance values greater than colonies, and flight distance was positively related to light pollution levels. Breeding habitat alteration by light pollution was more severe for inland colonies. We provide scientific-based information to manage dark refuges facilitating that fledglings from inland colonies reach the sea successfully. We also offer methodological approaches useful for other critically threatened petrel species grounded by light pollution.

  1. Demographic consequences of heavy metals and persistent organic pollutants in a vulnerable long-lived bird, the wandering albatross.

    PubMed

    Goutte, Aurélie; Barbraud, Christophe; Meillère, Alizée; Carravieri, Alice; Bustamante, Paco; Labadie, Pierre; Budzinski, Hélène; Delord, Karine; Cherel, Yves; Weimerskirch, Henri; Chastel, Olivier

    2014-07-22

    Seabirds are top predators of the marine environment that accumulate contaminants over a long life-span. Chronic exposure to pollutants is thought to compromise survival rate and long-term reproductive outputs in these long-lived organisms, thus inducing population decline. However, the demographic consequences of contaminant exposure are largely theoretical because of the dearth of long-term datasets. This study aims to test whether adult survival rate, return to the colony and long-term breeding performance were related to blood mercury (Hg), cadmium (Cd) and persistent organic pollutants (POPs), by using a capture-mark-recapture dataset on the vulnerable wandering albatross Diomedea exulans. We did not find evidence for any effect of contaminants on adult survival probability. However, blood Hg and POPs negatively impacted long-term breeding probability, hatching and fledging probabilities. The proximate mechanisms underlying these deleterious effects are likely multifaceted, through physiological perturbations and interactions with reproductive costs. Using matrix population models, we projected a demographic decline in response to an increase in Hg or POPs concentrations. This decline in population growth rate could be exacerbated by other anthropogenic perturbations, such as climate change, disease and fishery bycatch. This study gives a new dimension to the overall picture of environmental threats to wildlife populations.

  2. Recruitment of Polysynaptic Connections Underlies Functional Recovery of a Neural Circuit after Lesion.

    PubMed

    Sakurai, Akira; Tamvacakis, Arianna N; Katz, Paul S

    2016-01-01

    The recruitment of additional neurons to neural circuits often occurs in accordance with changing functional demands. Here we found that synaptic recruitment plays a key role in functional recovery after neural injury. Disconnection of a brain commissure in the nudibranch mollusc, Tritonia diomedea, impairs swimming behavior by eliminating particular synapses in the central pattern generator (CPG) underlying the rhythmic swim motor pattern. However, the CPG functionally recovers within a day after the lesion. The strength of a spared inhibitory synapse within the CPG from Cerebral Neuron 2 (C2) to Ventral Swim Interneuron B (VSI) determines the level of impairment caused by the lesion, which varies among individuals. In addition to this direct synaptic connection, there are polysynaptic connections from C2 and Dorsal Swim Interneurons to VSI that provide indirect excitatory drive but play only minor roles under normal conditions. After disconnecting the pedal commissure (Pedal Nerve 6), the recruitment of polysynaptic excitation became a major source of the excitatory drive to VSI. Moreover, the amount of polysynaptic recruitment, which changed over time, differed among individuals and correlated with the degree of recovery of the swim motor pattern. Thus, functional recovery was mediated by an increase in the magnitude of polysynaptic excitatory drive, compensating for the loss of direct excitation. Since the degree of susceptibility to injury corresponds to existing individual variation in the C2 to VSI synapse, the recovery relied upon the extent to which the network reorganized to incorporate additional synapses. PMID:27570828

  3. The effects of ingested plastic on growth and survival of albatross chicks

    USGS Publications Warehouse

    Sievert, Paul R.; Sileo, Louis

    1993-01-01

    We studied the effects of ingested plastic on the growth and survival of chicks of Laysan Albatrosses Diomedea immutabilis and Black-footed albatrosses D. nigripes on Midway Atoll during the nesting seasons of 1986 and 1987. Weights and proventricular contents of the chicks were determined periodically through the nesting cycle. Large (>22 cm1)volumes of plastic were present in the proventriculi of 27% of the Laysan and 16% of the Black-footed albatross chicks examined by endoscopy. Prior to fledging, albatross chicks regurgitated pellets composed of plastic and other indigestible material from their proventriculi. Laysan Albatross chicks with large volumes of proventricular plastic had asymptotic fledging weights significantly lower (122 g) than did chicks with low amounts of plastic. The effect of depresses fledging weights on postfledging survival was not determined. Plastic had no detectable effect on the growth of Black-footed Albatross chicks. All chicks that died were examined by necropsy. Mechanical lesions from ingested plastic were the cause of death of one of 45 Laysan Albatross chicks examined in 1986, but were not the cause of death of 93 individuals examined in 1987. Dehydration was the most common cause of death. In general, ingested plastic was not a significant direct cause of death in nestlings, but there was some evidence that it may have affected survival in 1986, when the volume of plastic ingested was highest.

  4. GPS tracking for mapping seabird mortality induced by light pollution.

    PubMed

    Rodríguez, Airam; Rodríguez, Beneharo; Negro, Juan J

    2015-01-01

    Light pollution and its consequences on ecosystems are increasing worldwide. Knowledge on the threshold levels of light pollution at which significant ecological impacts emerge and the size of dark refuges to maintain natural nocturnal processes is crucial to mitigate its negative consequences. Seabird fledglings are attracted by artificial lights when they leave their nest at night, causing high mortality. We used GPS data-loggers to track the flights of Cory's shearwater Calonectris diomedea fledglings from nest-burrows to ground, and to evaluate the light pollution levels of overflown areas on Tenerife, Canary Islands, using nocturnal, high-resolution satellite imagery. Birds were grounded at locations closer than 16 km from colonies in their maiden flights, and 50% were rescued within a 3 km radius from the nest-site. Most birds left the nests in the first three hours after sunset. Rescue locations showed radiance values greater than colonies, and flight distance was positively related to light pollution levels. Breeding habitat alteration by light pollution was more severe for inland colonies. We provide scientific-based information to manage dark refuges facilitating that fledglings from inland colonies reach the sea successfully. We also offer methodological approaches useful for other critically threatened petrel species grounded by light pollution. PMID:26035530

  5. GPS tracking for mapping seabird mortality induced by light pollution

    PubMed Central

    Rodríguez, Airam; Rodríguez, Beneharo; Negro, Juan J.

    2015-01-01

    Light pollution and its consequences on ecosystems are increasing worldwide. Knowledge on the threshold levels of light pollution at which significant ecological impacts emerge and the size of dark refuges to maintain natural nocturnal processes is crucial to mitigate its negative consequences. Seabird fledglings are attracted by artificial lights when they leave their nest at night, causing high mortality. We used GPS data-loggers to track the flights of Cory’s shearwater Calonectris diomedea fledglings from nest-burrows to ground, and to evaluate the light pollution levels of overflown areas on Tenerife, Canary Islands, using nocturnal, high-resolution satellite imagery. Birds were grounded at locations closer than 16 km from colonies in their maiden flights, and 50% were rescued within a 3 km radius from the nest-site. Most birds left the nests in the first three hours after sunset. Rescue locations showed radiance values greater than colonies, and flight distance was positively related to light pollution levels. Breeding habitat alteration by light pollution was more severe for inland colonies. We provide scientific-based information to manage dark refuges facilitating that fledglings from inland colonies reach the sea successfully. We also offer methodological approaches useful for other critically threatened petrel species grounded by light pollution. PMID:26035530

  6. Scale-dependent hierarchical adjustments of movement patterns in a long-range foraging seabird.

    PubMed

    Fritz, Hervé; Said, Sonia; Weimerskirch, Henri

    2003-06-01

    Foraging animals are expected to adjust their path according to the hierarchical spatial distribution of food resources and environmental factors. Studying such behaviour requires methods that allow for the detection of changes in pathways' characteristics across scales, i.e. a definition of scale boundaries and techniques to continuously monitor the precise movement of the animal over a sufficiently long period. We used a recently developed application of fractals, the changes in fractal dimension within a path and applied it to foraging trips over scales ranging across five orders of magnitude (10 m to 1000 km), using locations of wandering albatrosses (Diomedea exulans) recorded at 1 s intervals with a miniaturized global positioning system. Remarkably, all animals consistently showed the same pattern: the use of three scale-dependent nested domains where they adjust tortuosity to different environmental and behavioural constraints. At a small scale (ca. 100 m) they use a zigzag movement as they continuously adjust for optimal use of wind; at a medium scale (1-10 km), the movement shows changes in tortuosity consistent with food-searching behaviour; and at a large scale (greater than 10 km) the movement corresponds to commuting between patches and is probably influenced by large-scale weather systems. Our results demonstrate the possibility of identifying the hierarchical spatial scales at which long-ranging animals adjust their foraging behaviour, even in featureless environments such as oceans, and hence how to relate their movement patterns to environmental factors using an objective mathematical approach. PMID:12816652

  7. Do Seabirds Differ from Other Migrants in Their Travel Arrangements? On Route Strategies of Cory’s Shearwater during Its Trans-Equatorial Journey

    PubMed Central

    Dias, Maria P.; Granadeiro, José P.; Catry, Paulo

    2012-01-01

    Long-distance migrants have developed diverse strategies to deal with the challenges imposed by their annual journeys. These are relatively well studied in some avian groups, such as passerines, shorebirds and raptors. In contrast, few studies have addressed the migratory behaviour of pelagic birds in the light of current theories of optimal migration. Using a dataset of 100 complete migratory tracks gathered along four years, we performed a detailed study on the migratory strategy of a pelagic trans-equatorial migrant, the Cory’s shearwater Calonectris diomedea. We analysed daily routines, stopover ecology and travel speed, as well as the influence of the moon on several behavioural patterns. Cory’s shearwaters adopted a “fly-and-forage” strategy when migrating, similarly to what has been observed in some raptors. However, by flying by dynamic soaring, shearwaters attained high overall migration speeds, and were able to travel thousands of kilometres without making major stopovers and, apparently, without a noticeable pre-migratory fattening period. Other major findings of this study include the ability to adapt daily schedules when crossing major ecological barriers, and the constant adjustment of migration speed implying higher rates of travel in the pre-breeding movement, with a final sprint to the nesting colony. The present study also highlights a preference of Cory’s shearwaters for starting travel at twilight and documents a strong relationship between their migratory activity and the moon phase. PMID:23145168

  8. Lead exposure in Laysan albatross adults and chicks in Hawaii: prevalence, risk factors, and biochemical effects.

    USGS Publications Warehouse

    Work, T.M.; Smith, M.R.

    1996-01-01

    Prevalence of lead exposure and elevated tissue lead was determined in Laysan albatross (Diomedea immutabilis) in Hawaii. The relationship between lead exposure and proximity to buildings, between elevated blood lead and droopwing status, and elevated liver lead and presence of lead-containing paint chips in the proventriculus in albatross chicks was also examined. Finally, the effects of lead on the enzyme δ-amino-levulinic acid dehydratase (ALAD) was determined. There was a significant association between lead exposure or elevated tissue lead and proximity to buildings in albatross chicks and presence of lead paint chips in the proventriculus and elevated liver lead in carcasses. Although there was a significant association between elevated blood lead and droopwing chicks, there were notable exceptions. Prevalence of elevated tissue lead in albatross chicks was highest on Sand Island Midway and much less so on Kauai and virtually nonexistent in other areas. Prevalence of lead exposure decreased as numbers of buildings to which chicks were exposed on a given island decreased. Laysan albatross adults had minimal to no lead exposure. There was a significant negative correlation between blood lead concentration and ALAD activity in chicks. Based on ALAD activity, 0.03-0.05 μg/ml was the no effect range for blood lead in albatross chicks.

  9. Age-Related Variation in Foraging Behaviour in the Wandering Albatross at South Georgia: No Evidence for Senescence

    PubMed Central

    Froy, Hannah; Lewis, Sue; Catry, Paulo; Bishop, Charles M.; Forster, Isaac P.; Fukuda, Akira; Higuchi, Hiroyoshi; Phalan, Ben; Xavier, Jose C.; Nussey, Daniel H.; Phillips, Richard A.

    2015-01-01

    Age-related variation in demographic rates is now widely documented in wild vertebrate systems, and has significant consequences for population and evolutionary dynamics. However, the mechanisms underpinning such variation, particularly in later life, are less well understood. Foraging efficiency is a key determinant of fitness, with implications for individual life history trade-offs. A variety of faculties known to decline in old age, such as muscular function and visual acuity, are likely to influence foraging performance. We examine age-related variation in the foraging behaviour of a long-lived, wide-ranging oceanic seabird, the wandering albatross Diomedea exulans. Using miniaturised tracking technologies, we compared foraging trip characteristics of birds breeding at Bird Island, South Georgia. Based on movement and immersion data collected during the incubation phase of a single breeding season, and from extensive tracking data collected in previous years from different stages of the breeding cycle, we found limited evidence for age-related variation in commonly reported trip parameters, and failed to detect signs of senescent decline. Our results contrast with the limited number of past studies that have examined foraging behaviour in later life, since these have documented changes in performance consistent with senescence. This highlights the importance of studies across different wild animal populations to gain a broader perspective on the processes driving variation in ageing rates. PMID:25574995

  10. NeuronBank: A Tool for Cataloging Neuronal Circuitry

    PubMed Central

    Katz, Paul S.; Calin-Jageman, Robert; Dhawan, Akshaye; Frederick, Chad; Guo, Shuman; Dissanayaka, Rasanjalee; Hiremath, Naveen; Ma, Wenjun; Shen, Xiuyn; Wang, Hsui C.; Yang, Hong; Prasad, Sushil; Sunderraman, Rajshekhar; Zhu, Ying

    2010-01-01

    The basic unit of any nervous system is the neuron. Therefore, understanding the operation of nervous systems ultimately requires an inventory of their constituent neurons and synaptic connectivity, which form neural circuits. The presence of uniquely identifiable neurons or classes of neurons in many invertebrates has facilitated the construction of cellular-level connectivity diagrams that can be generalized across individuals within a species. Homologous neurons can also be recognized across species. Here we describe NeuronBank.org, a web-based tool that we are developing for cataloging, searching, and analyzing neuronal circuitry within and across species. Information from a single species is represented in an individual branch of NeuronBank. Users can search within a branch or perform queries across branches to look for similarities in neuronal circuits across species. The branches allow for an extensible ontology so that additional characteristics can be added as knowledge grows. Each entry in NeuronBank generates a unique accession ID, allowing it to be easily cited. There is also an automatic link to a Wiki page allowing an encyclopedic explanation of the entry. All of the 44 previously published neurons plus one previously unpublished neuron from the mollusc, Tritonia diomedea, have been entered into a branch of NeuronBank as have 4 previously published neurons from the mollusc, Melibe leonina. The ability to organize information about neuronal circuits will make this information more accessible, ultimately aiding research on these important models. PMID:20428500

  11. Olfaction and topography, but not magnetic cues, control navigation in a pelagic seabird: displacements with shearwaters in the Mediterranean Sea

    PubMed Central

    Pollonara, Enrica; Luschi, Paolo; Guilford, Tim; Wikelski, Martin; Bonadonna, Francesco; Gagliardo, Anna

    2015-01-01

    Pelagic seabirds wander the open oceans then return accurately to their habitual nest-sites. We investigated the effects of sensory manipulation on oceanic navigation in Scopoli’s shearwaters (Calonectris diomedea) breeding at Pianosa island (Italy), by displacing them 400 km from their colony and tracking them. A recent experiment on Atlantic shearwaters (Cory’s shearwater, Calonectris borealis) breeding in the Azores indicated a crucial role of olfaction over the open ocean, but left open the question of whether birds might navigate by topographical landmark cues when available. Our experiment was conducted in the Mediterranean sea, where the availability of topographical cues may provide an alternative navigational mechanism for homing. Magnetically disturbed shearwaters and control birds oriented homeward even when the coast was not visible and rapidly homed. Anosmic shearwaters oriented in a direction significantly different from the home direction when in open sea. After having approached a coastline their flight path changed from convoluted to homeward oriented, so that most of them eventually reached home. Beside confirming that magnetic cues appear unimportant for oceanic navigation by seabirds, our results support the crucial role of olfactory cues for birds’ navigation and reveal that anosmic shearwaters are able to home eventually by following coastal features. PMID:26548946

  12. Recruitment of Polysynaptic Connections Underlies Functional Recovery of a Neural Circuit after Lesion

    PubMed Central

    Tamvacakis, Arianna N.

    2016-01-01

    Abstract The recruitment of additional neurons to neural circuits often occurs in accordance with changing functional demands. Here we found that synaptic recruitment plays a key role in functional recovery after neural injury. Disconnection of a brain commissure in the nudibranch mollusc, Tritonia diomedea, impairs swimming behavior by eliminating particular synapses in the central pattern generator (CPG) underlying the rhythmic swim motor pattern. However, the CPG functionally recovers within a day after the lesion. The strength of a spared inhibitory synapse within the CPG from Cerebral Neuron 2 (C2) to Ventral Swim Interneuron B (VSI) determines the level of impairment caused by the lesion, which varies among individuals. In addition to this direct synaptic connection, there are polysynaptic connections from C2 and Dorsal Swim Interneurons to VSI that provide indirect excitatory drive but play only minor roles under normal conditions. After disconnecting the pedal commissure (Pedal Nerve 6), the recruitment of polysynaptic excitation became a major source of the excitatory drive to VSI. Moreover, the amount of polysynaptic recruitment, which changed over time, differed among individuals and correlated with the degree of recovery of the swim motor pattern. Thus, functional recovery was mediated by an increase in the magnitude of polysynaptic excitatory drive, compensating for the loss of direct excitation. Since the degree of susceptibility to injury corresponds to existing individual variation in the C2 to VSI synapse, the recovery relied upon the extent to which the network reorganized to incorporate additional synapses. PMID:27570828

  13. Foraging success of biological Lévy flights recorded in situ.

    PubMed

    Humphries, Nicolas E; Weimerskirch, Henri; Queiroz, Nuno; Southall, Emily J; Sims, David W

    2012-05-01

    It is an open question how animals find food in dynamic natural environments where they possess little or no knowledge of where resources are located. Foraging theory predicts that in environments with sparsely distributed target resources, where forager knowledge about resources' locations is incomplete, Lévy flight movements optimize the success of random searches. However, the putative success of Lévy foraging has been demonstrated only in model simulations. Here, we use high-temporal-resolution Global Positioning System (GPS) tracking of wandering (Diomedea exulans) and black-browed albatrosses (Thalassarche melanophrys) with simultaneous recording of prey captures, to show that both species exhibit Lévy and Brownian movement patterns. We find that total prey masses captured by wandering albatrosses during Lévy movements exceed daily energy requirements by nearly fourfold, and approached yields by Brownian movements in other habitats. These results, together with our reanalysis of previously published albatross data, overturn the notion that albatrosses do not exhibit Lévy patterns during foraging, and demonstrate that Lévy flights of predators in dynamic natural environments present a beneficial alternative strategy to simple, spatially intensive behaviors. Our findings add support to the possibility that biological Lévy flight may have naturally evolved as a search strategy in response to sparse resources and scant information. PMID:22529349

  14. Age-related variation in foraging behaviour in the wandering albatross at South Georgia: no evidence for senescence.

    PubMed

    Froy, Hannah; Lewis, Sue; Catry, Paulo; Bishop, Charles M; Forster, Isaac P; Fukuda, Akira; Higuchi, Hiroyoshi; Phalan, Ben; Xavier, Jose C; Nussey, Daniel H; Phillips, Richard A

    2015-01-01

    Age-related variation in demographic rates is now widely documented in wild vertebrate systems, and has significant consequences for population and evolutionary dynamics. However, the mechanisms underpinning such variation, particularly in later life, are less well understood. Foraging efficiency is a key determinant of fitness, with implications for individual life history trade-offs. A variety of faculties known to decline in old age, such as muscular function and visual acuity, are likely to influence foraging performance. We examine age-related variation in the foraging behaviour of a long-lived, wide-ranging oceanic seabird, the wandering albatross Diomedea exulans. Using miniaturised tracking technologies, we compared foraging trip characteristics of birds breeding at Bird Island, South Georgia. Based on movement and immersion data collected during the incubation phase of a single breeding season, and from extensive tracking data collected in previous years from different stages of the breeding cycle, we found limited evidence for age-related variation in commonly reported trip parameters, and failed to detect signs of senescent decline. Our results contrast with the limited number of past studies that have examined foraging behaviour in later life, since these have documented changes in performance consistent with senescence. This highlights the importance of studies across different wild animal populations to gain a broader perspective on the processes driving variation in ageing rates.

  15. Demographic consequences of heavy metals and persistent organic pollutants in a vulnerable long-lived bird, the wandering albatross

    PubMed Central

    Goutte, Aurélie; Barbraud, Christophe; Meillère, Alizée; Carravieri, Alice; Bustamante, Paco; Labadie, Pierre; Budzinski, Hélène; Delord, Karine; Cherel, Yves; Weimerskirch, Henri; Chastel, Olivier

    2014-01-01

    Seabirds are top predators of the marine environment that accumulate contaminants over a long life-span. Chronic exposure to pollutants is thought to compromise survival rate and long-term reproductive outputs in these long-lived organisms, thus inducing population decline. However, the demographic consequences of contaminant exposure are largely theoretical because of the dearth of long-term datasets. This study aims to test whether adult survival rate, return to the colony and long-term breeding performance were related to blood mercury (Hg), cadmium (Cd) and persistent organic pollutants (POPs), by using a capture–mark–recapture dataset on the vulnerable wandering albatross Diomedea exulans. We did not find evidence for any effect of contaminants on adult survival probability. However, blood Hg and POPs negatively impacted long-term breeding probability, hatching and fledging probabilities. The proximate mechanisms underlying these deleterious effects are likely multifaceted, through physiological perturbations and interactions with reproductive costs. Using matrix population models, we projected a demographic decline in response to an increase in Hg or POPs concentrations. This decline in population growth rate could be exacerbated by other anthropogenic perturbations, such as climate change, disease and fishery bycatch. This study gives a new dimension to the overall picture of environmental threats to wildlife populations. PMID:24920477

  16. Extreme variation in migration strategies between and within wandering albatross populations during their sabbatical year, and their fitness consequences

    PubMed Central

    Weimerskirch, Henri; Delord, Karine; Guitteaud, Audrey; Phillips, Richard A.; Pinet, Patrick

    2015-01-01

    Migratory behavior, routes and zones used during the non-breeding season are assumed to have been selected to maximize fitness, and can lead to genetic differentiation. Yet, here we show that migration strategies differ markedly between and within two genetically similar populations of wandering albatross Diomedea exulans from the Crozet and Kerguelen archipelagos in the Indian Ocean. Wandering albatrosses usually breed biennially if successful, and during the sabbatical year, all birds from Kerguelen migrate to the Pacific Ocean, whereas most from Crozet are sedentary. Instead of taking the shortest routes, which would involve a return against headwinds, migratory birds fly with the westerly winds, requiring detours of 10,000 s km. In total, migrants circumnavigate Antarctica 2 to 3 times, covering more than 120,000 km in a single sabbatical year. Our results indicate strong links between migratory behavior and fitness; all birds from Kerguelen breed biennially, whereas a significant proportion of those from Crozet, especially females, are sedentary and breed in consecutive calendar years. To breed annually, these females temporarily change mate, but return to their original partner in the following year. This extreme variation in migratory behavior has important consequences in term of life history evolution and susceptibility to climate change and fisheries. PMID:25747757

  17. Evidence for sex-segregated ocean distributions of first-winter wandering albatrosses at Crozet islands.

    PubMed

    Åkesson, Susanne; Weimerskirch, Henri

    2014-01-01

    The highly mobile wandering albatrosses (Diomedea exulans) are adapted to navigate the extreme environment of the Southern Ocean and return to isolated islands to breed. Each year they cover several hundreds of thousands of kilometers during travels across the sea. Little is known about the dispersal flights and migration of young albatrosses. We tracked, by satellite telemetry, the departure dispersal of 13 juvenile wandering albatrosses from the Crozet Islands and compared them with tracks of 7 unrelated adults during the interbreeding season. We used the satellite tracks to identify different behavioural steps of the inherited migration program used by juvenile wandering albatrosses during their first solo-migration. Our results show that the juvenile wandering albatrosses from Crozet Islands moved to sex-specific foraging zones of the ocean using at departures selectively the wind. The results suggest that the inherited migration program used by the juvenile wandering albatrosses encode several distinct steps, based on inherited preferred departure routes, differences in migration distance between sexes, and selective use of winds. During long transportation flights the albatrosses were influenced by winds and both adult and juveniles followed approximate loxodrome (rhumbline) routes coinciding with the foraging zone and the specific latitudes of their destination areas. During the long segments of transportation flights across open seas the juveniles selected routes at more northerly latitudes than adults.

  18. Ocean surface winds drive dynamics of transoceanic aerial movements.

    PubMed

    Felicísimo, Angel M; Muñoz, Jesús; González-Solis, Jacob

    2008-01-01

    Global wind patterns influence dispersal and migration processes of aerial organisms, propagules and particles, which ultimately could determine the dynamics of colonizations, invasions or spread of pathogens. However, studying how wind-mediated movements actually happen has been hampered so far by the lack of high resolution global wind data as well as the impossibility to track aerial movements. Using concurrent data on winds and actual pathways of a tracked seabird, here we show that oceanic winds define spatiotemporal pathways and barriers for large-scale aerial movements. We obtained wind data from NASA SeaWinds scatterometer to calculate wind cost (impedance) models reflecting the resistance to the aerial movement near the ocean surface. We also tracked the movements of a model organism, the Cory's shearwater (Calonectris diomedea), a pelagic bird known to perform long distance migrations. Cost models revealed that distant areas can be connected through "wind highways" that do not match the shortest great circle routes. Bird routes closely followed the low-cost "wind-highways" linking breeding and wintering areas. In addition, we found that a potential barrier, the near surface westerlies in the Atlantic sector of the Intertropical Convergence Zone (ITCZ), temporally hindered meridional trans-equatorial movements. Once the westerlies vanished, birds crossed the ITCZ to their winter quarters. This study provides a novel approach to investigate wind-mediated movements in oceanic environments and shows that large-scale migration and dispersal processes over the oceans can be largely driven by spatiotemporal wind patterns. PMID:18698354

  19. Pelagic seabird flight patterns are consistent with a reliance on olfactory maps for oceanic navigation.

    PubMed

    Reynolds, Andrew M; Cecere, Jacopo G; Paiva, Vitor H; Ramos, Jaime A; Focardi, Stefano

    2015-07-22

    Homing studies have provided tantalizing evidence that the remarkable ability of shearwaters (Procellariiformes) to pinpoint their breeding colony after crossing vast expanses of featureless open ocean can be attributed to their assembling cognitive maps of wind-borne odours but crucially, it has not been tested whether olfactory cues are actually used as a system for navigation. Obtaining statistically important samples of wild birds for use in experimental approaches is, however, impossible because of invasive sensory manipulation. Using an innovative non-invasive approach, we provide strong evidence that shearwaters rely on olfactory cues for oceanic navigation. We tested for compliance with olfactory-cued navigation in the flight patterns of 210 shearwaters of three species (Cory's shearwaters, Calonectris borealis, North Atlantic Ocean, Scopoli's shearwaters, C. diomedea Mediterranean Sea, and Cape Verde shearwaters, C. edwardsii, Central Atlantic Ocean) tagged with high-resolution GPS loggers during both incubation and chick rearing.We found that most (69%) birds displayed exponentially truncated scale-free(Lévy-flight like) displacements, which we show are consistent with olfactory-cued navigation in the presence of atmospheric turbulence. Our analysis provides the strongest evidence yet for cognitive odour map navigation in wild birds. Thus, we may reconcile two highly disputed questions in movement ecology, by mechanistically connecting Lévy displacements and olfactory navigation. Our approach can be applied to any species which can be tracked at sufficient spatial resolution, using a GPS logger. PMID:26136443

  20. Comparative mapping of GABA-immunoreactive neurons in the central nervous systems of nudibranch molluscs.

    PubMed

    Gunaratne, Charuni A; Sakurai, Akira; Katz, Paul S

    2014-03-01

    The relative simplicity of certain invertebrate nervous systems, such as those of gastropod molluscs, allows behaviors to be dissected at the level of small neural circuits composed of individually identifiable neurons. Elucidating the neurotransmitter phenotype of neurons in neural circuits is important for understanding how those neural circuits function. In this study, we examined the distribution of γ-aminobutyric-acid;-immunoreactive (GABA-ir) neurons in four species of sea slugs (Mollusca, Gastropoda, Opisthobranchia, Nudibranchia): Tritonia diomedea, Melibe leonina, Dendronotus iris, and Hermissenda crassicornis. We found consistent patterns of GABA immunoreactivity in the pedal and cerebral-pleural ganglia across species. In particular, there were bilateral clusters in the lateral and medial regions of the dorsal surface of the cerebral ganglia as well as a cluster on the ventral surface of the pedal ganglia. There were also individual GABA-ir neurons that were recognizable across species. The invariant presence of these individual neurons and clusters suggests that they are homologous, although there were interspecies differences in the numbers of neurons in the clusters. The GABAergic system was largely restricted to the central nervous system, with the majority of axons confined to ganglionic connectives and commissures, suggesting a central, integrative role for GABA. GABA was a candidate inhibitory neurotransmitter for neurons in central pattern generator (CPG) circuits underlying swimming behaviors in these species, however none of the known swim CPG neurons were GABA-ir. Although the functions of these GABA-ir neurons are not known, it is clear that their presence has been strongly conserved across nudibranchs. PMID:24638845

  1. Comparative Mapping of GABA-Immunoreactive Neurons in the Buccal Ganglia of Nudipleura Molluscs.

    PubMed

    Gunaratne, Charuni A; Katz, Paul S

    2016-04-15

    Phylogenetic comparisons of neurotransmitter distribution are important for understanding the ground plan organization of nervous systems. This study describes the γ-aminobutyric acid (GABA)-immunoreactive (GABA-ir) neurons in the buccal ganglia of six sea slug species (Mollusca, Gastropoda, Euthyneura, Nudipleura). In the nudibranch species, Hermissenda crassicornis, Tritonia diomedea, Tochuina tetraquetra, and Dendronotus iris, the number of GABA-ir neurons was highly consistent. Another nudibranch, Melibe leonina, however, contained approximately half the number of GABA-ir neurons. This may relate to its loss of a radula and its unique feeding behavior. The GABA immunoreactivity in a sister group to the nudibranchs, Pleurobranchaea californica, differed drastically from that of the nudibranchs. Not only did it have significantly more GABA-ir neurons but it also had a unique GABA distribution pattern. Furthermore, unlike the nudibranchs, the Pleurobranchaea GABA distribution was also different from that of other, more distantly related, euopisthobranch and panpulmonate snails and slugs. This suggests that the Pleurobranchaea GABA distribution may be a derived feature, unique to this lineage. The majority of GABA-ir axons and neuropil in the Nudipleura were restricted to the buccal ganglia, commissures, and connectives. However, in Tritonia and Pleurobranchaea, we detected a few GABA-ir fibers in buccal nerves that innervate feeding muscles. Although the specific functions of the GABA-ir neurons in the species in this study are not known, the innervation pattern suggests these neurons may play an integrative or regulatory role in bilaterally coordinated behaviors in the Nudipleura. PMID:26355705

  2. Should animals navigating over short distances switch to a magnetic compass sense?

    PubMed

    Wyeth, Russell C

    2010-01-01

    Magnetoreception can play a substantial role in long distance navigation by animals. I hypothesize that locomotion guided by a magnetic compass sense could also play a role in short distance navigation. Animals identify mates, prey, or other short distance navigational goals using different sensory modalities (olfaction, vision, audition, etc.) to detect sensory cues associated with those goals. In conditions where these cues become unreliable for navigation (due to flow changes, obstructions, noise interference, etc.), switching to a magnetic compass sense to guide locomotion toward the navigational goals could be beneficial. Using simulations based on known locomotory and flow parameters, I show this strategy has strong theoretical benefits for the nudibranch mollusk Tritonia diomedea navigating toward odor sources in variable flow. A number of other animals may garner similar benefits, particularly slow-moving species in environments with rapidly changing cues relevant for navigation. Faster animals might also benefit from switching to a magnetic compass sense, provided the initial cues used for navigation (acoustic signals, odors, etc.) are intermittent or change rapidly enough that the entire navigation behavior cannot be guided by a continuously detectable cue. Examination of the relative durations of navigational tasks, the persistence of navigational cues, and the stability of both navigators and navigational targets will identify candidates with the appropriate combination of unreliable initial cues and relatively immobile navigational goals for which this hypothetical behavior could be beneficial. Magnetic manipulations can then test whether a switch to a magnetic compass sense occurs. This hypothesis thus provides an alternative when considering the behavioral significance of a magnetic compass sense in animals. PMID:20740070

  3. Oxygen profiles in egg masses predicted from a diffusion-reaction model.

    PubMed

    Woods, H Arthur; Moran, Amy L

    2008-03-01

    We developed a novel diffusion-reaction model to describe spatial and temporal changes in oxygen concentrations in gelatinous egg masses containing live, respiring embryos. We used the model in two ways. First, we constructed artificial egg masses of known metabolic density using embryos of the Antarctic sea urchin Sterechnius neumayeri, measured radial oxygen profiles at two temperatures, and compared our measurements to simulated radial oxygen profiles generated by the model. We parameterized the model by measuring the radius of the artificial masses, metabolic densities (=embryo metabolic rate x embryo density) and oxygen diffusion coefficients at both ambient (-1.5 degrees C) or slightly warmer (+1.5-2 degrees C) temperatures. Simulated and measured radial oxygen profiles were similar, indicating that the model captured the major biological features determining oxygen distributions. Second, we used the model to analyze sources of error in step-change experiments for determining oxygen diffusion coefficients (D), and to determine the suitability of simpler, analytical equations for estimating D. Our analysis indicated that embryo metabolism can lead to large (several-fold) overestimates of D if the analytical equation is fitted to step-down-traces of central oxygen concentration (i.e. external oxygen concentration stepped from some high value to zero). However, good estimates of D were obtained from step-up-traces. We used these findings to estimate D in egg masses of three species of nudibranch molluscs: two Antarctic species (Tritonia challengeriana and Tritoniella belli; -1.5 and +2 degrees C) and one temperate Pacific species (Tritonia diomedea; 12 and 22 degrees C). D for all three species was approximately 8 x 10(-6) cm(2) s(-1), and there was no detectable effect of temperature on estimated D. For the Antarctic species, D in egg masses was 70-90% of its value in seawater of similar temperature. PMID:18281342

  4. Homology and homoplasy of swimming behaviors and neural circuits in the Nudipleura (Mollusca, Gastropoda, Opisthobranchia)

    PubMed Central

    Newcomb, James M.; Sakurai, Akira; Lillvis, Joshua L.; Gunaratne, Charuni A.; Katz, Paul S.

    2012-01-01

    How neural circuit evolution relates to behavioral evolution is not well understood. Here the relationship between neural circuits and behavior is explored with respect to the swimming behaviors of the Nudipleura (Mollusca, Gastropoda, Opithobranchia). Nudipleura is a diverse monophyletic clade of sea slugs among which only a small percentage of species can swim. Swimming falls into a limited number of categories, the most prevalent of which are rhythmic left–right body flexions (LR) and rhythmic dorsal–ventral body flexions (DV). The phylogenetic distribution of these behaviors suggests a high degree of homoplasy. The central pattern generator (CPG) underlying DV swimming has been well characterized in Tritonia diomedea and in Pleurobranchaea californica. The CPG for LR swimming has been elucidated in Melibe leonina and Dendronotus iris, which are more closely related. The CPGs for the categorically distinct DV and LR swimming behaviors consist of nonoverlapping sets of homologous identified neurons, whereas the categorically similar behaviors share some homologous identified neurons, although the exact composition of neurons and synapses in the neural circuits differ. The roles played by homologous identified neurons in categorically distinct behaviors differ. However, homologous identified neurons also play different roles even in the swim CPGs of the two LR swimming species. Individual neurons can be multifunctional within a species. Some of those functions are shared across species, whereas others are not. The pattern of use and reuse of homologous neurons in various forms of swimming and other behaviors further demonstrates that the composition of neural circuits influences the evolution of behaviors. PMID:22723353

  5. Metals in Laysan albatrosses from Midway Atoll.

    PubMed

    Burger, J; Gochfeld, M

    2000-02-01

    We examined the concentrations of lead, cadmium, selenium, chromium, manganese, arsenic, tin, and mercury in the heart, liver, kidney, salt gland, and feathers of adult (n = 10) and young (n = 15) Laysan albatrosses (Diomedea immutabilis) from Midway Atoll in the north-central Pacific Ocean. Lead poisoning has been reported in some Laysans nesting near buildings on Midway, but other heavy metals have not been examined. We examined tissue distribution of metals by age and gender (adults only). We also examined tissue concentrations in three birds with a droop-wing syndrome characteristic of lead poisoning. We compared metal levels in salt gland (a special excretory organ of marine birds) with those in other tissues. All metals varied significantly across tissues in both adults and chicks, and the relative tissue concentrations were similar in adults and chicks for most metals. Adults had higher levels of most metals in most organs, with significant differences mainly for cadmium (up to 20 x higher in kidney and salt gland) and for mercury (17 x higher in kidney). However, chicks had significantly higher manganese in liver and arsenic in salt gland. The salt gland had concentrations of most metals (except cadmium, selenium, and mercury) comparable to the kidney levels, which is consistent with it serving as an excretory organ for the cations. Chicks with droop-wings had very elevated levels of lead in their tissue (16.8 ppm in feathers, 14 ppm in liver and kidney), whereas levels of other metals were not significantly different from the apparently normal chicks.

  6. An holistic ecological analysis of the diet of Cory's shearwaters using prey morphological characters and DNA barcoding.

    PubMed

    Alonso, Hany; Granadeiro, José P; Waap, Silke; Xavier, José; Symondson, William O C; Ramos, Jaime A; Catry, Paulo

    2014-08-01

    Knowledge of the dietary choices and trophic niches of organisms is the key to understanding their roles in ecosystems. In seabird diet studies, prey identification is a difficult challenge, often yielding results with technique-specific biases. Additionally, sampling efforts are often not extensive enough to reveal intrapopulational variation. Immature animals, which may constitute up to 50% of a population, may occupy a significantly different trophic niche to more experienced birds, but this remains largely unexplored. We investigated the diet of Cory's shearwater (Calonectris diomedea) from Selvagem Grande, an island located off the northwest African coast, collecting a total of 698 regurgitate samples over three consecutive breeding seasons. The diet was assessed using two complementary approaches for prey identification: conventional morphological analysis (using fish vertebrae, otoliths and cephalopod beaks) and DNA barcoding of the 16S rRNA mitochondrial gene, in cases where a positive identification could not be retrieved. Species assignments employed BLAST and distance-based methods, as well as direct optimization of the tree length based on unaligned sequences in POY. This method resulted in robust tree estimates and species assignments, showing its potential for DNA barcoding of stomach contents using hypervariable markers such as the 16S. The molecular approach increased taxonomic resolution and revealed an additional 17 taxa. Diet differed significantly according to breeding status, sex, breeding phase (prelaying and chick rearing) and year. Such direct evidence of trophic segregation within the same population has rarely been shown in seabirds and highlights the importance of including such variables in ecosystem-based management approaches. PMID:24806079

  7. Buying Years to Extinction: Is Compensatory Mitigation for Marine Bycatch a Sufficient Conservation Measure for Long-Lived Seabirds?

    PubMed Central

    Forero, Manuela G.; Oro, Daniel

    2009-01-01

    Along the lines of the ‘polluter pays principle’, it has recently been proposed that the local long-line fishing industry should fund eradication of terrestrial predators at seabird breeding colonies, as a compensatory measure for the bycatch caused by the fishing activity. The measure is economically sound, but a quantitative and reliable test of its biological efficacy has never been conducted. Here, we investigated the demographic consequences of predator eradication for Cory's shearwater Calonectris diomedea, breeding in the Mediterranean, using a population model that integrates demographic rates estimated from individual life-history information with experimental measures of predation and habitat structure. We found that similar values of population growth rate can be obtained by different combinations of habitat characteristics, predator abundance and adult mortality, which explains the persistence of shearwater colonies in islands with introduced predators. Even so, given the empirically obtained values of survival, all combinations of predator abundance and habitat characteristics projected a decline in shearwater numbers. Perturbation analyses indicated that the value and the sensitivity of shearwater population growth rates were affected by all covariates considered and their interactions. A decrease in rat abundance delivered only a small increase in the population growth rate, whereas a change in adult survival (a parameter independent of rat abundance) had the strongest impact on population dynamics. When adult survival is low, rat eradication would allow us to “buy” years before extinction but does not reverse the process. Rat eradication can therefore be seen as an emergency measure if threats on adult survival are eliminated in the medium-term period. For species with low fecundity and long life expectancy, our results suggest that rat control campaigns are not a sufficient, self-standing measure to compensate the biological toll of long

  8. Comparative mapping of GABA-immunoreactive neurons in the central nervous systems of nudibranch molluscs.

    PubMed

    Gunaratne, Charuni A; Sakurai, Akira; Katz, Paul S

    2014-03-01

    The relative simplicity of certain invertebrate nervous systems, such as those of gastropod molluscs, allows behaviors to be dissected at the level of small neural circuits composed of individually identifiable neurons. Elucidating the neurotransmitter phenotype of neurons in neural circuits is important for understanding how those neural circuits function. In this study, we examined the distribution of γ-aminobutyric-acid;-immunoreactive (GABA-ir) neurons in four species of sea slugs (Mollusca, Gastropoda, Opisthobranchia, Nudibranchia): Tritonia diomedea, Melibe leonina, Dendronotus iris, and Hermissenda crassicornis. We found consistent patterns of GABA immunoreactivity in the pedal and cerebral-pleural ganglia across species. In particular, there were bilateral clusters in the lateral and medial regions of the dorsal surface of the cerebral ganglia as well as a cluster on the ventral surface of the pedal ganglia. There were also individual GABA-ir neurons that were recognizable across species. The invariant presence of these individual neurons and clusters suggests that they are homologous, although there were interspecies differences in the numbers of neurons in the clusters. The GABAergic system was largely restricted to the central nervous system, with the majority of axons confined to ganglionic connectives and commissures, suggesting a central, integrative role for GABA. GABA was a candidate inhibitory neurotransmitter for neurons in central pattern generator (CPG) circuits underlying swimming behaviors in these species, however none of the known swim CPG neurons were GABA-ir. Although the functions of these GABA-ir neurons are not known, it is clear that their presence has been strongly conserved across nudibranchs.

  9. Neurochemical and neuroanatomical identification of central pattern generator neuron homologues in Nudipleura molluscs.

    PubMed

    Lillvis, Joshua L; Gunaratne, Charuni A; Katz, Paul S

    2012-01-01

    Certain invertebrate neurons can be identified by their behavioral functions. However, evolutionary divergence can cause some species to not display particular behaviors, thereby making it impossible to use physiological characteristics related to those behaviors for identifying homologous neurons across species. Therefore, to understand the neural basis of species-specific behavior, it is necessary to identify homologues using characteristics that are independent of physiology. In the Nudipleura mollusc Tritonia diomedea, Cerebral Neuron 2 (C2) was first described as being a member of the swim central pattern generator (CPG). Here we demonstrate that neurochemical markers, in conjunction with previously known neuroanatomical characteristics, allow C2 to be uniquely identified without the aid of electrophysiological measures. Specifically, C2 had three characteristics that, taken together, identified the neuron: 1) a white cell on the dorsal surface of the cerebral ganglion, 2) an axon that projected to the contralateral pedal ganglion and through the pedal commissure, and 3) immunoreactivity for the peptides FMRFamide and Small Cardioactive Peptide B. These same anatomical and neurochemical characteristics also uniquely identified the C2 homologue in Pleurobranchaea californica (called A1), which was previously identified by its analogous role in the Pleurobranchaea swim CPG. Furthermore, these characteristics were used to identify C2 homologues in Melibe leonina, Hermissenda crassicornis, and Flabellina iodinea, species that are phylogenetically closer to Tritonia than Pleurobranchaea, but do not display the same swimming behavior as Tritonia or Pleurobranchaea. These identifications will allow future studies comparing and contrasting the physiological properties of C2 across species that can and cannot produce the type of swimming behavior exhibited by Tritonia.

  10. Should Animals Navigating Over Short Distances Switch to a Magnetic Compass Sense?

    PubMed Central

    Wyeth, Russell C.

    2010-01-01

    Magnetoreception can play a substantial role in long distance navigation by animals. I hypothesize that locomotion guided by a magnetic compass sense could also play a role in short distance navigation. Animals identify mates, prey, or other short distance navigational goals using different sensory modalities (olfaction, vision, audition, etc.) to detect sensory cues associated with those goals. In conditions where these cues become unreliable for navigation (due to flow changes, obstructions, noise interference, etc.), switching to a magnetic compass sense to guide locomotion toward the navigational goals could be beneficial. Using simulations based on known locomotory and flow parameters, I show this strategy has strong theoretical benefits for the nudibranch mollusk Tritonia diomedea navigating toward odor sources in variable flow. A number of other animals may garner similar benefits, particularly slow-moving species in environments with rapidly changing cues relevant for navigation. Faster animals might also benefit from switching to a magnetic compass sense, provided the initial cues used for navigation (acoustic signals, odors, etc.) are intermittent or change rapidly enough that the entire navigation behavior cannot be guided by a continuously detectable cue. Examination of the relative durations of navigational tasks, the persistence of navigational cues, and the stability of both navigators and navigational targets will identify candidates with the appropriate combination of unreliable initial cues and relatively immobile navigational goals for which this hypothetical behavior could be beneficial. Magnetic manipulations can then test whether a switch to a magnetic compass sense occurs. This hypothesis thus provides an alternative when considering the behavioral significance of a magnetic compass sense in animals. PMID:20740070

  11. Do naive juvenile seabirds forage differently from adults?

    PubMed Central

    Riotte-Lambert, Louise; Weimerskirch, Henri

    2013-01-01

    Foraging skills of young individuals are assumed to be inferior to those of adults. The reduced efficiency of naive individuals may be the primary cause of the high juvenile mortality and explain the deferment of maturity in long-lived species. However, the study of juvenile and immature foraging behaviour has been limited so far. We used satellite telemetry to compare the foraging movements of juveniles, immatures and breeding adult wandering albatrosses Diomedea exulans, a species where foraging success is positively influenced by the distance covered daily. We showed that juveniles are able to use favourable winds as soon as the first month of independence, but cover shorter distances daily and spend more time sitting on water than adults during the first two months after fledging. These reduced movement capacities do not seem to be the cause of higher juvenile mortality. Moreover, juveniles almost never restrict their movement to specific areas, as adults and immatures frequently do over shelf edges or oceanic zones, which suggest that the location of appropriate areas is learned through experience. Immatures and adults have equivalent movement capacities, but when they are central place foragers, i.e. when adults breed or immatures come to the colony to display and pair, immatures make shorter trips than adults. The long duration of immaturity in this species seems to be related to a long period of learning to integrate the foraging constraints associated with reproduction and central place foraging. Our results indicate that foraging behaviour of young albatrosses is partly innate and partly learned progressively over immaturity. The first months of learning appear critical in terms of survival, whereas the long period of immaturity is necessary for young birds to attain the skills necessary for efficient breeding without fitness costs. PMID:23926153

  12. Successful eradication of the European rabbit (Oryctolagus cuniculus) and house mouse (Mus musculus) from the island of Selvagem Grande (Macaronesian archipelago), in the Eastern Atlantic.

    PubMed

    Olivera, Paulo; Menezes, Dilia; Trout, Roger; Buckle, Alan; Geraldes, Pedro; Jesus, José

    2010-03-01

    The Portuguese island of Selvagem Grande (Great Salvage) in Macaronesia is an important seabird breeding station in the eastern Atlantic. Significant populations of Cory's shearwater Calonectris diomedea (Scopoli, 1769), Bulwer's petrel Bulweria bulweria (Jardine & Selby, 1828) and little shearwater Puffinus assimilis baroli (Bonaparte, 1857) are present, and white-faced storm-petrel Pelagodroma marina (Latham, 1790) and Madeiran storm-petrel Oceanodroma castro (Harcourt, 1851) populations are of global significance. Selvagem Grande also provides diverse habitats for an extensive flora, including 11 endemic species. The 270-ha island was also inhabited by two alien invasive mammals: the European rabbit Oryctolagus cuniculus (Linnaeus, 1758) and the house mouse Mus musculus (Linnaeus, 1758). Both are known to have had adverse impacts on breeding seabirds and island vegetation. In 2002, the Natural Park of Madeira conducted a program using brodifacoum bait formulations aimed at rabbit and mouse eradication. Approximately 17 000 individual baiting points were established on a 12.5 × 12.5 m grid. Baits were also applied by hand "seeding" on steep slopes and cliffs where bait stations could not be placed. Rabbits were removed after a month. However, mice persisted for considerably longer and strategic bait applications against them continued for a further six months. Subsequent assessments by trapping, bait takes and systematic observation of signs over three years, has confirmed the removal of both alien invasive species. This paper presents information on these operations, on measures adopted to mitigate adverse impacts of the eradication program on important vertebrate non-target species, including Berthelot's pipit Anthus berthelotii Bolle, 1862 and a species of gecko Tarentola bischoffi Joger, 1984 and on the initial response of the island's ecosystem to the eradication of rabbits and mice. PMID:21392324

  13. Association of heavy metals with metallothionein and other proteins in hepatic cytosol of marine mammals and seabirds.

    PubMed

    Ikemoto, Tokutaka; Kunito, Takashi; Anan, Yasumi; Tanaka, Hiroyuki; Baba, Norihisa; Miyazaki, Nobuyuki; Tanabe, Shinsuke

    2004-08-01

    Distribution of Cu, Zn, Cd, Ag, Hg, and Se were determined in hepatocytosol of northern fur seals (Callorhinus ursinus), black-footed albatrosses (Diomedea nigripes), and Dall's porpoises (Phocoenoides dalli). Copper, Zn, and Cd were accumulated preferentially in metallothionein (MT) fraction and their contents in MT fraction increased with the amounts in the hepatocytosol. Silver was bound to both high-molecular-weight substances (HMWS) and MT in the hepatocytosol for all three species, whereas the distribution of Ag in the cytosol was different among the three species. In northern fur seals, Ag mainly was bound to MT, whereas it mainly was associated with HMWS in Dall's porpoises. In contrast, Ag was distributed almost equally in both HMWS and MT for black-footed albatrosses. Mercury content in HMWS and Se content in HMWS and low-molecular-weight substances (LMWS) increased with their contents in hepatocytosol for all the three species. A significant positive correlation was found between Se and Hg contents in high-molecular weight (HMW) fraction in cytosol. The molar ratio of Hg and Se was close to unity in HMW fraction of the specimens with high Hg concentration in cytosol, implying that the Hg-Se complex was bound to the HMWS. Analysis of metals in the hepatocytosol by high-performance liquid chromatography/inductively coupled plasma-mass spectrometry (HPLC/ICP-MS) suggests that multiple isoforms of MT are present in hepatocytosol of the three species and that the metal profiles in hepatocytosols are different among the species. To our knowledge, this is the first report on the association of Ag with HMWS and MT in hepatocytosol of marine mammals and seabirds. Also, distribution and interaction of Hg and Se were investigated for the first time in hepatocytosol of the higher trophic marine animals. PMID:15352491

  14. Seabird bycatch in Alaska demersal longline fishery trials: a demographic summary

    USGS Publications Warehouse

    Phillips, Elizabeth M.; Nevins, HannahRose M.; Hatch, Scott A.; Ramey, Andy M.; Miller, Melissa A.; Harvey, James T.

    2010-01-01

    The seasonal and spatial demographics are summarized for seabirds killed incidentally during gear modification trials for a demersal longline fishery in the Bering Sea. We examined 417 carcasses, including Northern Fulmar Fulmarus glacialis (n = 205), Glaucous-winged Gull Larus glaucescens (n = 103), Short-tailed Shearwater Puffinus tenuirostris (n = 48), Glaucous Gull Larus hyperboreus (n = 23), Slaty-backed Gull Larus schistisagus (n = 4), Black-legged Kittiwake Rissa tridactyla (n = 1), Laysan Albatross Diomedea immutabilis (n = 1), and unidentified gull species Larus spp. (n = 32). There was a significant male bias in the sex ratio of fulmars but not of gulls or shearwaters. For the top three species killed, the age composition of resident species was dominated numerically by adults (Northern Fulmar—86%; Glaucous-winged Gull—63%), whereas migrant species were primarily immature birds (Short-tailed Shearwater—71%). The majority of migratory Short-tailed Shearwaters (88%) were caught in July and August, whereas 70% of resident fulmars and gulls were caught in October and November. Age-class frequencies did not differ by month of capture, indicating that adult mortality is substantial. Eighty percent of the fulmars caught during July and August were within 200 km of two colonies in the Bering Sea, whereas only 7% of fulmars were caught in the same area during September to November. This is one of the first demographic summaries of seabird bycatch in Alaska longline fisheries. Additional studies of the species, age and sex of seabirds subject to fisheries-related mortality will provide data necessary to evaluate population-level impacts.

  15. Impact of changing wind conditions on foraging and incubation success in male and female wandering albatrosses.

    PubMed

    Cornioley, Tina; Börger, Luca; Ozgul, Arpat; Weimerskirch, Henri

    2016-09-01

    Wind is an important climatic factor for flying animals as by affecting their locomotion, it can deeply impact their life-history characteristics. In the context of globally changing wind patterns, we investigated the mechanisms underlying recently reported increase in body mass of a population of wandering albatrosses (Diomedea exulans) with increasing wind speed over time. We built a foraging model detailing the effects of wind on movement statistics and ultimately on mass gained by the forager and mass lost by the incubating partner. We then simulated the body mass of incubating pairs under varying wind scenarios. We tracked the frequency at which critical mass leading to nest abandonment was reached to assess incubation success. We found that wandering albatrosses behave as time minimizers during incubation as mass gain was independent of any movement statistics but decreased with increasing mass at departure. Individuals forage until their energy requirements, which are determined by their body conditions, are fulfilled. This can come at the cost of their partner's condition as mass loss of the incubating partner depended on trip duration. This behaviour is consistent with strategies of long-lived species which favoured their own survival over their current reproductive attempt. In addition, wind speed increased ground speed which in turn reduced trip duration and males foraged further away than females at high ground speed. Contrasted against an independent data set, the simulation performed satisfactorily for males but less so for females under current wind conditions. The simulation predicted an increase in male body mass growth rate with increasing wind speed, whereas females' rate decreased. This trend may provide an explanation for the observed increase in mass of males but not of females. Conversely, the simulation predicted very few nest abandonments, which is in line with the high breeding success of this species and is contrary to the hypothesis that

  16. Analysis of anomalous fluctuations in the dynamics of complex biophysical systems

    NASA Astrophysics Data System (ADS)

    Viswanathan, Gandhimohan M.

    1997-08-01

    We apply methods based on scaling ideas to analyze fluctuations in three representative complex biophysical systems at (i) the macromolecular level; (ii) the physiological level; and (iii) the level of complete organisms and their ecosystems. At the macromolecular and biopolymer levels, we investigate the mosaic structure ('patchiness') of genomic DNA. We introduce and develop new techniques to quantify DNA patchiness which involve calculating functions which measure correlations at length scale l and detect distinct characteristic patch sizes embedded in scale invariant patch size distributions. Using these new methods, we address a number of issues relating to the structure and evolution of genomic DNA. At the physiological level, we investigate the dynamics of heartbeats. We test the hypothesis that the scaling properties of the dynamics of healthy physiological systems are more stable than those of pathological systems by studying beat-to- beat fluctuations in human heart rate. By analyzing extremely long data sets of up to N = 105 beats for 11 healthy subjects, we find that the fluctuations in heart rate scale approximately uniformly over several temporal orders of magnitude. By contrast, we find that in data sets of comparable length for 14 subjects with heart disease, the fluctuations grow erratically-indicating a loss of scaling stability. At the level of complete organisms and their interacting ecosystems, we investigate the biophysics of foraging. We study the foraging behavior of the Wandering Albatross Diomedea exulans, and find a power law distribution of flight time intervals. We interpret this behavior in terms of Levy flights, which are a class of random walks whose step lengths are not constant but rather are chosen from a probability distribution with a power law tail. We furthermore interpret our finding of temporal scale invariance in terms of a scale-invariant spatial distribution of food on the ocean surface. I conclude by examining the

  17. Age-related mate choice in the wandering albatross.

    PubMed

    Jouventin; Lequette; Dobson

    1999-05-01

    We studied mate choice in the wandering albatross, Diomedea exulans, using data from 32 years of banding returns in the population of the Crozet Islands. We studied mating choices in a single year, when the Crozet Islands population was male biased (8:5, males:females). Thus, we expected that females might show great flexibility of choice of partners. Because age and experience might influence mate choice, we tested the expectation that females would choose the oldest and most experienced males for pair bonding. Pair bonds usually last until one member of the pair dies (0.3% of the birds 'divorce'), so mate choice should be especially important. We found that the ages of males and females in both displaying and bonded (breeding) pairs were significantly correlated. These age-associated pairings were not a passive phenomenon, but appeared to be due to an active process of selection of mates of similar age. First-time breeders sought mates of similar age, but preferred those with the most experience. Remating, experienced birds whose mates had died did not pair with individuals of significantly similar age, but predominantly paired with other widowed birds that, on average, were also relatively old. Mate fidelity in wandering albatrosses may be due to the cost of finding and bonding with a new mate. Pair bonds, and thus breeding, took an average of 3.2 and 2.3 years to establish, for males and females, respectively. Thus, remating exerts a potential average reproductive cost of about 15% of lifetime reproductive success. Copyright 1999 The Association for the Study of Animal Behaviour. PMID:10328796

  18. Colony Foundation in an Oceanic Seabird

    PubMed Central

    Munilla, Ignacio; Genovart, Meritxell; Paiva, Vitor H.; Velando, Alberto

    2016-01-01

    Seabirds are colonial vertebrates that despite their great potential for long-range dispersal and colonization are reluctant to establish in novel locations, often recruiting close to their natal colony. The foundation of colonies is therefore a rare event in most seabird species and little is known about the colonization process in this group. The Cory’s shearwater (Calonectris diomedea) is a pelagic seabird that has recently established three new colonies in Galicia (NE Atlantic) thus expanding its distribution range 500 km northwards. This study aimed to describe the establishment and early progress of the new Galician populations and to determine the genetic and morphometric characteristics of the individuals participating in these foundation events. Using 10 microsatellite loci, we tested the predictions supported by different seabird colonization models. Possibly three groups of non-breeders, adding up to around 200 birds, started visiting the Galician colonies in the mid 2000’s and some of them eventually laid eggs and reproduced, thus establishing new breeding colonies. The Galician populations showed a high genetic diversity and a frequency of private alleles similar to or even higher than some of the large historical populations. Most individuals were assigned to several Atlantic populations and a few (if any) to Mediterranean colonies. Our study suggests that a large and admixed population is settling in Galicia, in agreement with predictions from island metapopulation models of colonization. Multiple source colonies imply that some birds colonizing Galicia were dispersing from very distant colonies (> 1500 km). Long-distance colonizations undertaken by relatively large and admixed groups of colonizers can help to explain the low levels of genetic structure over vast areas that are characteristic of most oceanic seabird species. PMID:26909694

  19. Colony Foundation in an Oceanic Seabird.

    PubMed

    Munilla, Ignacio; Genovart, Meritxell; Paiva, Vitor H; Velando, Alberto

    2016-01-01

    Seabirds are colonial vertebrates that despite their great potential for long-range dispersal and colonization are reluctant to establish in novel locations, often recruiting close to their natal colony. The foundation of colonies is therefore a rare event in most seabird species and little is known about the colonization process in this group. The Cory's shearwater (Calonectris diomedea) is a pelagic seabird that has recently established three new colonies in Galicia (NE Atlantic) thus expanding its distribution range 500 km northwards. This study aimed to describe the establishment and early progress of the new Galician populations and to determine the genetic and morphometric characteristics of the individuals participating in these foundation events. Using 10 microsatellite loci, we tested the predictions supported by different seabird colonization models. Possibly three groups of non-breeders, adding up to around 200 birds, started visiting the Galician colonies in the mid 2000's and some of them eventually laid eggs and reproduced, thus establishing new breeding colonies. The Galician populations showed a high genetic diversity and a frequency of private alleles similar to or even higher than some of the large historical populations. Most individuals were assigned to several Atlantic populations and a few (if any) to Mediterranean colonies. Our study suggests that a large and admixed population is settling in Galicia, in agreement with predictions from island metapopulation models of colonization. Multiple source colonies imply that some birds colonizing Galicia were dispersing from very distant colonies (> 1500 km). Long-distance colonizations undertaken by relatively large and admixed groups of colonizers can help to explain the low levels of genetic structure over vast areas that are characteristic of most oceanic seabird species. PMID:26909694

  20. Impact of changing wind conditions on foraging and incubation success in male and female wandering albatrosses.

    PubMed

    Cornioley, Tina; Börger, Luca; Ozgul, Arpat; Weimerskirch, Henri

    2016-09-01

    Wind is an important climatic factor for flying animals as by affecting their locomotion, it can deeply impact their life-history characteristics. In the context of globally changing wind patterns, we investigated the mechanisms underlying recently reported increase in body mass of a population of wandering albatrosses (Diomedea exulans) with increasing wind speed over time. We built a foraging model detailing the effects of wind on movement statistics and ultimately on mass gained by the forager and mass lost by the incubating partner. We then simulated the body mass of incubating pairs under varying wind scenarios. We tracked the frequency at which critical mass leading to nest abandonment was reached to assess incubation success. We found that wandering albatrosses behave as time minimizers during incubation as mass gain was independent of any movement statistics but decreased with increasing mass at departure. Individuals forage until their energy requirements, which are determined by their body conditions, are fulfilled. This can come at the cost of their partner's condition as mass loss of the incubating partner depended on trip duration. This behaviour is consistent with strategies of long-lived species which favoured their own survival over their current reproductive attempt. In addition, wind speed increased ground speed which in turn reduced trip duration and males foraged further away than females at high ground speed. Contrasted against an independent data set, the simulation performed satisfactorily for males but less so for females under current wind conditions. The simulation predicted an increase in male body mass growth rate with increasing wind speed, whereas females' rate decreased. This trend may provide an explanation for the observed increase in mass of males but not of females. Conversely, the simulation predicted very few nest abandonments, which is in line with the high breeding success of this species and is contrary to the hypothesis that

  1. Albatross populations in peril: A population trajectory for Black-browed Albatrosses at South Georgia

    USGS Publications Warehouse

    Arnold, J.M.; Brault, S.; Croxall, J.P.

    2006-01-01

    Simulation modeling was used to reconstruct Black-browed Albatross (Diomedea melanophris) population trends. Close approximations to observed data were accomplished by annually varying survival rates, reproductive success, and probabilities of returning to breed given success in previous years. The temporal shift in annual values coincided with the start of longline fishing at South Georgia and potential changes in krill abundance. We used 23 years of demographic data from long-term studies of a breeding colony of this species at Bird Island, South Georgia, to validate our model. When we used annual parameter estimates for survival, reproductive success, and probabilities of returning to breed given success in previous years, our model trajectory closely followed the observed changes in breeding population size over time. Population growth rate was below replacement (lambda < 1) in most years and was most sensitive to changes in adult survival. This supports the recent IUCN uplisting of this species from "Vulnerable" to "Endangered." Comparison of pre-1988 and post-1988 demography (before and after the inception of a longline fishery in the breeding area) reveals a decrease in lambda from 0.963 to 0.910. A life table response experiment (LTRE) showed that this decline in lambda was caused mostly by declines in survival of adults. If 1988-1998 demographic rates are maintained, the model predicts a 98% chance of a population of fewer than 25 pairs within 78 years. For this population to recover to a status under which it could be "delisted," a 10% increase in survival of all age classes would be needed. ?? 2006 by the Ecological Society of America.

  2. Buying years to extinction: is compensatory mitigation for marine bycatch a sufficient conservation measure for long-lived seabirds?

    PubMed

    Igual, José Manuel; Tavecchia, Giacomo; Jenouvrier, Stephanie; Forero, Manuela G; Oro, Daniel

    2009-01-01

    Along the lines of the 'polluter pays principle', it has recently been proposed that the local long-line fishing industry should fund eradication of terrestrial predators at seabird breeding colonies, as a compensatory measure for the bycatch caused by the fishing activity. The measure is economically sound, but a quantitative and reliable test of its biological efficacy has never been conducted. Here, we investigated the demographic consequences of predator eradication for Cory's shearwater Calonectris diomedea, breeding in the Mediterranean, using a population model that integrates demographic rates estimated from individual life-history information with experimental measures of predation and habitat structure. We found that similar values of population growth rate can be obtained by different combinations of habitat characteristics, predator abundance and adult mortality, which explains the persistence of shearwater colonies in islands with introduced predators. Even so, given the empirically obtained values of survival, all combinations of predator abundance and habitat characteristics projected a decline in shearwater numbers. Perturbation analyses indicated that the value and the sensitivity of shearwater population growth rates were affected by all covariates considered and their interactions. A decrease in rat abundance delivered only a small increase in the population growth rate, whereas a change in adult survival (a parameter independent of rat abundance) had the strongest impact on population dynamics. When adult survival is low, rat eradication would allow us to "buy" years before extinction but does not reverse the process. Rat eradication can therefore be seen as an emergency measure if threats on adult survival are eliminated in the medium-term period. For species with low fecundity and long life expectancy, our results suggest that rat control campaigns are not a sufficient, self-standing measure to compensate the biological toll of long

  3. Combined Spatio-Temporal Impacts of Climate and Longline Fisheries on the Survival of a Trans-Equatorial Marine Migrant

    PubMed Central

    Ramos, Raül; Granadeiro, José Pedro; Nevoux, Marie; Mougin, Jean-Louis; Dias, Maria Peixe; Catry, Paulo

    2012-01-01

    Predicting the impact of human activities and their derivable consequences, such as global warming or direct wildlife mortality, is increasingly relevant in our changing world. Due to their particular life history traits, long-lived migrants are amongst the most endangered and sensitive group of animals to these harming effects. Our ability to identify and quantify such anthropogenic threats in both breeding and wintering grounds is, therefore, of key importance in the field of conservation biology. Using long-term capture-recapture data (34 years, 4557 individuals) and year-round tracking data (4 years, 100 individuals) of a trans-equatorial migrant, the Cory’s shearwater (Calonectris diomedea), we investigated the impact of longline fisheries and climatic variables in both breeding and wintering areas on the most important demographic trait of this seabird, i.e. adult survival. Annual adult survival probability was estimated at 0.914±0.022 on average, declining throughout 1978–1999 but recovering during the last decade (2005–2011). Our results suggest that both the incidental bycatch associated with longline fisheries and high sea surface temperatures (indirectly linked to food availability; SST) increased mortality rates during the long breeding season (March-October). Shearwater survival was also negatively affected during the short non-breeding season (December-February) by positive episodes of the Southern Oscillation Index (SOI). Indirect negative effects of climate at both breeding (SST) and wintering grounds (SOI) had a greater impact on survival than longliner activity, and indeed these climatic factors are those which are expected to present more unfavourable trends in the future. Our work underlines the importance of considering both breeding and wintering habitats as well as precise schedules/phenology when assessing the global role of the local impacts on the dynamics of migratory species. PMID:22815833

  4. An holistic ecological analysis of the diet of Cory's shearwaters using prey morphological characters and DNA barcoding.

    PubMed

    Alonso, Hany; Granadeiro, José P; Waap, Silke; Xavier, José; Symondson, William O C; Ramos, Jaime A; Catry, Paulo

    2014-08-01

    Knowledge of the dietary choices and trophic niches of organisms is the key to understanding their roles in ecosystems. In seabird diet studies, prey identification is a difficult challenge, often yielding results with technique-specific biases. Additionally, sampling efforts are often not extensive enough to reveal intrapopulational variation. Immature animals, which may constitute up to 50% of a population, may occupy a significantly different trophic niche to more experienced birds, but this remains largely unexplored. We investigated the diet of Cory's shearwater (Calonectris diomedea) from Selvagem Grande, an island located off the northwest African coast, collecting a total of 698 regurgitate samples over three consecutive breeding seasons. The diet was assessed using two complementary approaches for prey identification: conventional morphological analysis (using fish vertebrae, otoliths and cephalopod beaks) and DNA barcoding of the 16S rRNA mitochondrial gene, in cases where a positive identification could not be retrieved. Species assignments employed BLAST and distance-based methods, as well as direct optimization of the tree length based on unaligned sequences in POY. This method resulted in robust tree estimates and species assignments, showing its potential for DNA barcoding of stomach contents using hypervariable markers such as the 16S. The molecular approach increased taxonomic resolution and revealed an additional 17 taxa. Diet differed significantly according to breeding status, sex, breeding phase (prelaying and chick rearing) and year. Such direct evidence of trophic segregation within the same population has rarely been shown in seabirds and highlights the importance of including such variables in ecosystem-based management approaches.

  5. Association of heavy metals with metallothionein and other proteins in hepatic cytosol of marine mammals and seabirds.

    PubMed

    Ikemoto, Tokutaka; Kunito, Takashi; Anan, Yasumi; Tanaka, Hiroyuki; Baba, Norihisa; Miyazaki, Nobuyuki; Tanabe, Shinsuke

    2004-08-01

    Distribution of Cu, Zn, Cd, Ag, Hg, and Se were determined in hepatocytosol of northern fur seals (Callorhinus ursinus), black-footed albatrosses (Diomedea nigripes), and Dall's porpoises (Phocoenoides dalli). Copper, Zn, and Cd were accumulated preferentially in metallothionein (MT) fraction and their contents in MT fraction increased with the amounts in the hepatocytosol. Silver was bound to both high-molecular-weight substances (HMWS) and MT in the hepatocytosol for all three species, whereas the distribution of Ag in the cytosol was different among the three species. In northern fur seals, Ag mainly was bound to MT, whereas it mainly was associated with HMWS in Dall's porpoises. In contrast, Ag was distributed almost equally in both HMWS and MT for black-footed albatrosses. Mercury content in HMWS and Se content in HMWS and low-molecular-weight substances (LMWS) increased with their contents in hepatocytosol for all the three species. A significant positive correlation was found between Se and Hg contents in high-molecular weight (HMW) fraction in cytosol. The molar ratio of Hg and Se was close to unity in HMW fraction of the specimens with high Hg concentration in cytosol, implying that the Hg-Se complex was bound to the HMWS. Analysis of metals in the hepatocytosol by high-performance liquid chromatography/inductively coupled plasma-mass spectrometry (HPLC/ICP-MS) suggests that multiple isoforms of MT are present in hepatocytosol of the three species and that the metal profiles in hepatocytosols are different among the species. To our knowledge, this is the first report on the association of Ag with HMWS and MT in hepatocytosol of marine mammals and seabirds. Also, distribution and interaction of Hg and Se were investigated for the first time in hepatocytosol of the higher trophic marine animals.

  6. Oxygen in egg masses: interactive effects of temperature, age, and egg-mass morphology on oxygen supply to embryos.

    PubMed

    Moran, Amy L; Woods, H Arthur

    2007-02-01

    model is developed to provide a quantitative means of estimating primary and interactive effects of the different factors. We also show that in T. diomedea the gel itself is the main barrier to oxygen transport into egg masses, and that the metabolic activity of embryos increases substantially when embryos are artificially released from the capsules that contain them within the gel mass. PMID:17267657

  7. Contrasting effects of climatic variability on the demography of a trans-equatorial migratory seabird.

    PubMed

    Genovart, Meritxell; Sanz-Aguilar, Ana; Fernández-Chacón, Albert; Igual, Jose M; Pradel, Roger; Forero, Manuela G; Oro, Daniel

    2013-01-01

    Large-scale seasonal climatic indices, such as the North Atlantic Oscillation (NAO) index or the Southern Oscillation Index (SOI), account for major variations in weather and climate around the world and may influence population dynamics in many organisms. However, assessing the extent of climate impacts on species and their life-history traits requires reliable quantitative statistical approaches. We used a new analytical tool in mark-recapture, the multi-event modelling, to simultaneously assess the influence of climatic variation on multiple demographic parameters (i.e. adult survival, transient probability, reproductive skipping and nest dispersal) at two Mediterranean colonies of the Cory's shearwater Calonectris diomedea, a trans-equatorial migratory long-lived seabird. We also analysed the impact of climate in the breeding success at the two colonies. We found a clear temporal variation of survival for Cory's shearwaters, strongly associated to the large-scale SOI especially in one of the colonies (up to 66% of variance explained). Atlantic hurricane season is modulated by the SOI and coincides with shearwater migration to their wintering areas, directly affecting survival probabilities. However, the SOI was a better predictor of survival probabilities than the frequency of hurricanes; thus, we cannot discard an indirect additive effect of SOI via food availability. Accordingly, the proportion of transients was also correlated with SOI values, indicating higher costs of first reproduction (resulting in either mortality or permanent dispersal) when bad environmental conditions occurred during winter before reproduction. Breeding success was also affected by climatic factors, the NAO explaining c. 41% of variance, probably as a result of its effect in the timing of peak abundance of squid and small pelagics, the main prey for shearwaters. No climatic effect was found either on reproductive skipping or on nest dispersal. Contrarily to what we expect for a long

  8. Oxygen in egg masses: interactive effects of temperature, age, and egg-mass morphology on oxygen supply to embryos.

    PubMed

    Moran, Amy L; Woods, H Arthur

    2007-02-01

    model is developed to provide a quantitative means of estimating primary and interactive effects of the different factors. We also show that in T. diomedea the gel itself is the main barrier to oxygen transport into egg masses, and that the metabolic activity of embryos increases substantially when embryos are artificially released from the capsules that contain them within the gel mass.

  9. Discusión de las aproximaciones utilizadas en el estudio de la recombinación dielectrónica de los metales en envolturas estelares

    NASA Astrophysics Data System (ADS)

    Cruzado, A.; di Rocco, H. O.; Ringuelet, A.

    Se calcularon nuevos parámetros atómicos del MgI reemplazando los niveles de energía teóricos por los observados. Con ellos se calculó nuevamente el flujo originado en la Recombinación Dielectrónica (RD) del MgII y se comparó con resultados anteriores. Se evaluó también la posible influencia de diferentes fuentes de opacidad, en el flujo originado en la RD de los metales en atmósferas extendidas de estrellas tempranas. En particular, se calculó la profundidad óptica de las líneas de MgI para diferentes condiciones físicas del medio.

  10. Longline fishing (how what you don't know can hurt you).

    PubMed

    Fitzgerald, Kevin T

    2013-11-01

    Longline fishing utilizes monofilament lines that can be as much as 62 miles long. The line itself is buoyed by Styrofoam or plastic floats. Usually, at about every 100ft, a secondary line is attached and hangs down from the mainline. The lines are baited with mackerel, squid, or shark meat and have as many as 10,000 hooks. Every 12-24 hours, the line is hauled in, mechanically rebaited, and set back into the water behind the vessel. The baited hooks can be seen by albatross and other seabirds as they are placed in the water or being hauled out. When the birds dive for the bait, they are hooked, dragged behind the fishing boat, and drown. Spectacularly nonselective, longline fishing techniques also hook many other forms of marine life-"bycatch" (sea turtles, seals, dolphins, penguins, sharks, and many other nontarget finfish). It is estimated that 300,000 seabirds (including 100,000 albatross) die on longlines each year. Albatross are among the longest-lived birds. They can live up to 60 years and some species do not start breeding until they are 10 years old. They have a low reproductive rate and many species only breed every other year. In addition, a species like the Wandering Albatross (Diomedea exulans) rears its chicks for an average of more than 270 days. Albatross pair for life and may take years to find a new partner if their mate is killed. Owing to their incredibly low reproductive rate, albatross are particularly vulnerable to longline fishing. Currently, it is believed that 4 albatross drown per 100,000 hooks set. This is more than 400 birds a week. The current mortality rate for adult birds is not sustainable and for some species, the birds are dying faster that they can repopulate. Currently, 19 of the world's 22 albatross species are threatened with extinction. This year longline fishing ships will set 10 billion hooks worldwide. Various mitigation measures (bird-scaring lines, weighted, faster-sinking line, setting lines deeper out of the bird

  11. Longline fishing (how what you don't know can hurt you).

    PubMed

    Fitzgerald, Kevin T

    2013-11-01

    Longline fishing utilizes monofilament lines that can be as much as 62 miles long. The line itself is buoyed by Styrofoam or plastic floats. Usually, at about every 100ft, a secondary line is attached and hangs down from the mainline. The lines are baited with mackerel, squid, or shark meat and have as many as 10,000 hooks. Every 12-24 hours, the line is hauled in, mechanically rebaited, and set back into the water behind the vessel. The baited hooks can be seen by albatross and other seabirds as they are placed in the water or being hauled out. When the birds dive for the bait, they are hooked, dragged behind the fishing boat, and drown. Spectacularly nonselective, longline fishing techniques also hook many other forms of marine life-"bycatch" (sea turtles, seals, dolphins, penguins, sharks, and many other nontarget finfish). It is estimated that 300,000 seabirds (including 100,000 albatross) die on longlines each year. Albatross are among the longest-lived birds. They can live up to 60 years and some species do not start breeding until they are 10 years old. They have a low reproductive rate and many species only breed every other year. In addition, a species like the Wandering Albatross (Diomedea exulans) rears its chicks for an average of more than 270 days. Albatross pair for life and may take years to find a new partner if their mate is killed. Owing to their incredibly low reproductive rate, albatross are particularly vulnerable to longline fishing. Currently, it is believed that 4 albatross drown per 100,000 hooks set. This is more than 400 birds a week. The current mortality rate for adult birds is not sustainable and for some species, the birds are dying faster that they can repopulate. Currently, 19 of the world's 22 albatross species are threatened with extinction. This year longline fishing ships will set 10 billion hooks worldwide. Various mitigation measures (bird-scaring lines, weighted, faster-sinking line, setting lines deeper out of the bird

  12. Demographic rates of northern royal albatross at Taiaroa Head, New Zealand.

    PubMed

    Richard, Yvan; Perriman, Lyndon; Lalas, Chris; Abraham, Edward R

    2015-01-01

    Demographic rates, such as annual survival rate, are generally difficult to estimate for long-lived seabirds, because of the length of time required for this kind of study and the remoteness of colonies. However, a small colony of northern royal albatross (Diomedea sanfordi) established itself on the mainland of New Zealand at Taiaroa Head, making possible regular banding and monitoring of its individuals since the first chick fledged, in 1938. Data on the presence/absence of birds, as well as on breeding outcomes, were available for the period from 1989-90 to 2011-12, and included 2128 annual resightings of 355 banded individuals of known age. The main goal of the present study was to estimate the annual survival rate of juveniles, pre-breeders, and adults at Taiaroa Head. These rates were estimated simultaneously in a single Bayesian multi-state capture-recapture model. Several models were fitted to the data, with different levels of complexity. From the most parsimonious model, the overall annual adult survival rate was estimated as 0.950 (95% CI [0.941-0.959]). In this model, adult survival declined with age, from 0.976 (95% CI [0.963-0.988]) at 6 years, the minimum age at first breeding, to 0.915 (95% CI [0.879-0.946]) at 40 years. Mean annual survival of pre-breeders was 0.966 (95% CI [0.950-0.980]), and 0.933 (95% CI [0.908-0.966]) for juveniles. There was no discernible difference in survival between males and females, and there was no apparent trend in survival over time. Estimates of other demographic rates were also obtained during the estimation process. The mean age at first return of juveniles to the colony was estimated as 4.8 years (95% CI [4.6-5.1]), and the mean age at first breeding as 8.9 years (95% CI [8.5-9.3]). Because all the birds of the colony were banded, it was possible to estimate the total population size. The number of northern royal albatross present annually at the Taiaroa Head colony has doubled since 1989-90, and the current total

  13. Depth of the base of the Jackson aquifer, based on geophysical exploration, southern Jackson Hole, Wyoming, USA

    NASA Astrophysics Data System (ADS)

    Nolan, Bernard T.; Campbell, David L.; Senterfit, Robert M.

    ées ont été krigées afin d'estimer la profondeur de la base de la formation aquifère dans la partie sud de Jackson Hole. Les cartes d'isovaleurs d'estimation krigées indiquent que la profondeur de la base de la formation aquifère de Jackson est faible dans la partie centrale de la zone d'étude à l'est et à l'ouest des monts Gros Ventre, plus grande dans le secteur ouest près de la zone faillée de Teton, et faible sur la bordure sud de Jackson Hole. Les profondeurs estimées vont de 30m au sud, près des confluences des rivières Spring et Flat avec la rivière Snake, à 210m à l'ouest près de la ville de Wilson (Wyoming). Resumen Se llevó a cabo una campaña geofísica para determinar la profundidad del basamento de un acuífero libre en la zona sur de Jackson Hole, Wyoming, EEUU. USA. Medidas audio-magnetotelúricas (ATM) en 77 lugares de la zona de estudio dieron lugar a registros de resistividad eléctrica del subsuelo, que se usaron para inferir los cambios litológicos con la profundidad. Los depósitos superficiales, saturados y no consolidados de edad cuaternaria, el acuífero de Jackson, forman una capa de resistencia geoeléctrica entre 100-600ohm-m. La profundidad media de la base del acuífero de Jackson se estima en unos 61m (200pies), a partir de 62 registros con medidas suficientes. Los valores ATM fueron krigeados para obtener una medida de la profundidad del basamento del acuífero en la zona sur de Jackson Hole. Los mapas de isoprofundidades obtenidos por krigeado indican que el acuífero es poco profundo en la parte central de la zona de estudio, cerca de los Gros Ventre Buttes orientales y occidentales, más profundo al oeste, cerca del sistema de fallas de Teton, y menos profundo en el borde sur de Jackson Hole. Las profundidades van desde 30m (100pies) en el sur, en la confluencia entre los desfiladeros Spring y Flat con el Río Snake, hasta 210m (700pies) al oeste, cerca de la ciudad de Wilson, Wyoming.

  14. Estimation of the depth to the fresh-water/salt-water interface from vertical head gradients in wells in coastal and island aquifers

    NASA Astrophysics Data System (ADS)

    Izuka, Scot K.; Gingerich, Stephen B.

    gradients verticaux de charge à partir des mesures de niveau piézométrique faites en cours de foration d'un puits incomplet; le gradient est alors utilisé pour estimer la profondeur de l'interface. L'application de cette méthode à un système eau douce - eau salée simulé numériquement montre que la méthode est la plus précise lorsque le gradient est mesuré dans un puits pénétrant profondément dans l'aquifère. Même en utilisant un puits peu profond, la méthode estime la position de l'interface avec plus de précision que ne le fait la relation de Ghyben-Herzberg lorsqu'il existe un gradient vertical de charge bien marqué. L'application de la méthode à des données de terrain montre que la foration, les méthodes de mesure de niveau et les hétérogénéités au sein de l'aquifère peuvent être la cause de difficultés, mais que les effets de ces difficultés peuvent être réduits. Resumen Para la estimación de la productividad de pozos en acuíferos costeros y en islas es necesaria una estimación precisa de la profundidad de la interfaz teórica entre agua dulce y agua salada. La relación de Ghyben-Herzberg, usada habitualmente para estimar la profundidad de la interfaz, puede subestimar o sobrestimar el espesor de agua dulce, al asumir la ausencia de flujos y gradientes verticales. La estimación de la profundidad de la interfaz debe considerar tanto estos gradientes verticales, como la posible anisotropía del acuífero. En este artículo se presenta un método para calcular los gradientes verticales de niveles a partir de las medidas obtenidas durante la perforación de un pozo parcialmente penetrante para, a partir de este gradiente, estimar la profundidad de la interfaz. La aplicación del método a un sistema de agua dulce/agua salada simulado numéricamente muestra que el método es más preciso cuando el gradiente se mide en un pozo profundo. Incluso en el caso de un pozo superficial, el método permite una estimación más precisa de la

  15. La implantacion del enfoque constructivista en el aula de ciencia: Estudio de caso multiple

    NASA Astrophysics Data System (ADS)

    Arroyo Betancourt, Luz I.

    Esta investigacion estudia la implantacion del enfoque constructivista en tres aulas de ciencia del contexto puertorriqueno. Se auscultaron las practicas educativas que utilizan maestras consideradas constructivistas y la correspondencia de sus practicas educativas con los elementos esenciales de la didactica que proponen los teoricos de los planteamientos constructivistas. Se ausculto, ademas, a que vision del enfoque constructivista responden las expresiones de las maestras acerca de su practica educativa y como compara con su quehacer, a la luz de los elementos esenciales de las visiones constructivistas piagetiana, social y radical. Se utilizo el diseno de estudio descriptivo de caso multiple. El estudio se baso en entrevistas a profundidad, revision de documentos y observacion no participativa a la sala de clases. El contexto fueron tres escuelas publicas de la Region Educativa de San Juan, una elemental, una intermedia y una superior. Los resultados confirmaron que la transicion hacia el enfoque constructivista es un proceso que toma tiempo, dedicacion y la participacion en adiestramientos y readiestramientos acerca del nuevo enfoque. Las maestras coinciden en la mayoria de las practicas educativas que utilizan para implantar el enfoque constructivista de ensenanza y difieren en algunas debido, probablemente, a que han tenido que adaptarlas a los correspondientes niveles de ensenanza: elemental, intermedio y superior. Dos de las maestras planifican por conceptos generadores, mientras que una de ellas planifica siguiendo la guia que recibe del Departamento de Educacion. Difieren ademas, en el enfasis que confieren al inquirir cientifico. Con relacion a la correspondencia entre la vision manifestada por las maestras a la luz de las visiones piagetiana, social y radical, aparentemente, las preguntas del protocolo de entrevistas no lograron evocar la informacion con suficiente profundidad, por lo que la investigadora tuvo que inferir las visiones de las

  16. Perspectivas para mejorar la salud sexual de las minorías sexuales y de identidad de género en Guatemala

    PubMed Central

    Alonzo, Jorge; Mann, Lilli; Simán, Florence; Sun, Christina J.; Andrade, Mario; Villatoro, Guillermo; Rhodes, Scott D.

    2016-01-01

    Resumen Las minorías sexuales y de identidad de género en Guatemala son afectadas de manera desproporcionada por el VIH y otras infecciones transmitidas sexualmente (ITS). Sin embargo, poco se sabe de los factores que contribuyen al riesgo de infección en estas minorías. Investigadores de Estados Unidos y Guatemala quisimos informarnos sobre las necesidades de salud sexual e identificar características de programas de prevención de VIH/ITS para estas minorías. Llevamos a cabo 8 grupos focales con hombres gay, bisexuales y personas transgénero y entrevistas en profundidad con líderes comunitarios. Utilizamos el Método Comparativo Constante para analizar las transcripciones. Identificamos 24 factores que influyen en la salud sexual y 16 características de programas para reducir el riesgo de VIH/ITS en estas poblaciones. La identificación de factores de conductas sexuales de riesgo y de características de programas potencialmente efectivos ofrece gran potencial para desarrollar intervenciones que contribuyan a reducir el riesgo de infección por VIH/ITS en estas minorías en Guatemala. PMID:27494000

  17. Incentivos para atraer y retener personal de salud de zonas rurales del Perú: un estudio cualitativo

    PubMed Central

    Huicho, Luis; Canseco, Francisco Díez; Lema, Claudia; Miranda, J. Jaime; Lescano, Andrés G.

    2014-01-01

    El objetivo fue identificar incentivos de atracción y retención en zonas rurales y distantes de Ayacucho, Perú. Fueron realizadas entrevistas en profundidad con 80 médicos, enfermeras, obstetras y técnicos (20 por grupo) de las zonas más pobres y con 11 funcionarios. No existen políticas sistemáticas de atracción y retención de personal de salud en Ayacucho. Los principales incentivos, en orden de importancia, fueron mejoras salariales, oportunidades de formación y capacitación, estabilidad laboral y nombramiento, mejoras en infraestructura y equipos, e incremento del personal. Se mencionaron también mejoras en la vivienda y alimentación, mayor cercanía con la familia y reconocimiento por el sistema de salud. Existen coincidencias y singularidades entre los distintos grupos sobre los incentivos clave para estimular el trabajo rural, que deben considerarse al diseñar políticas públicas. Las iniciativas del Estado deben comprender procesos rigurosos de monitoreo y evaluación, para asegurar que las mismas tengan el impacto deseado. PMID:22488318

  18. A psf-fitting pipeline for VVV-ESO: The star cluster Pismis 24

    NASA Astrophysics Data System (ADS)

    Dias, R. A. G.; Bonatto, C.

    2014-10-01

    Este trabalho apresenta um algoritmo para a extração de dados fotométricos do catálogo "VISTA Variables in the Via Láctea" (VVV) do ESO. A principal característica do algoritmo é evitar a interação com o usuário mantendo precisão e profundidade fotométrica, de fato o algoritmo foi capaz de gerar dados mais precisos para as estrelas menos brilhantes (J gtrsim 16, H gtrsim 15,5 e H gtrsim 15) e confiável fotometria para estrelas mais de uma magnitude mais fracas do que as detectáveis com outras técnicas. Embora o algoritmo obtenha resultados menos precisos para as estrelas mais brilhantes, este provou ser o método mais adequado, uma vez que queremos trabalhar com aglomerados abertos jovens, onde a pré-sequência principal é de maior importância. Além disso, podemos combinar 2MASS e VVV para substituir as estrelas saturadas do VVV.

  19. Las dificultades de sentir: el rol de las emociones en la estigmatización del VIH/SIDA

    PubMed Central

    MARZÁN-RODRÍGUEZ, Melissa; VARAS-DÍAZ, Nelson

    2009-01-01

    Resumen El Virus de Inmunodeficiencia Humana (VIH) y el Síndrome de Inmunodeficiencia Adquirida (SIDA) han sido motivo de estigmatización para las personas que viven con ellos. Esta estigmatización se ha estudiado consecuentemente desde la perspectiva de opiniones de agentes estigmatizantes. Estas opiniones han obviado sistemáticamente el rol de las emociones en el proceso de estigmatización. Llevamos a cabo este estudio con el propósito de identificar el rol de las emociones en el proceso de estigmatización de las personas que viven con el virus (PVVS) por parte de profesionales de la salud. Para lograr este objetivo utilizamos un diseño exploratorio y cualitativo en el cual utilizamos la técnica de entrevistas semiestructuradas a profundidad. La muestra estuvo compuesta por 80 profesionales de la salud y estudiantes de las siguientes especialidades: psicología, trabajo social, medicina y enfermería. Los resultados reflejaron la existencia de emociones asociadas al VIH/SIDA tales como pena, lástima, compasión, asco, fobia y miedo entre los/as profesionales y estudiantes que participaron. Las personas participantes evidenciaron la necesidad de controlar sus emociones al interactuar con PVVS. Los resultados apuntan a la necesidad de explorar aquellos factores que mediatizan las emociones, tales como el contexto social en que se manifiestan y ante quiénes se revelan, para lograr entender a cabalidad el estigma que rodea al VIH/SIDA. PMID:20212916

  20. PubMed

    Marzán-Rodríguez, Melissa; Varas-Díaz, Nelson

    2006-01-01

    El Virus de Inmunodeficiencia Humana (VIH) y el Síndrome de Inmunodeficiencia Adquirida (SIDA) han sido motivo de estigmatización para las personas que viven con ellos. Esta estigmatización se ha estudiado consecuentemente desde la perspectiva de opiniones de agentes estigmatizantes. Estas opiniones han obviado sistemáticamente el rol de las emociones en el proceso de estigmatización. Llevamos a cabo este estudio con el propósito de identificar el rol de las emociones en el proceso de estigmatización de las personas que viven con el virus (PVVS) por parte de profesionales de la salud. Para lograr este objetivo utilizamos un diseño exploratorio y cualitativo en el cual utilizamos la técnica de entrevistas semiestructuradas a profundidad. La muestra estuvo compuesta por 80 profesionales de la salud y estudiantes de las siguientes especialidades: psicología, trabajo social, medicina y enfermería. Los resultados reflejaron la existencia de emociones asociadas al VIH/SIDA tales como pena, lástima, compasión, asco, fobia y miedo entre los/as profesionales y estudiantes que participaron. Las personas participantes evidenciaron la necesidad de controlar sus emociones al interactuar con PVVS. Los resultados apuntan a la necesidad de explorar aquellos factores que mediatizan las emociones, tales como el contexto social en que se manifiestan y ante quiénes se revelan, para lograr entender a cabalidad el estigma que rodea al VIH/SIDA.

  1. [Bariatric surgery in adults: variables that facilitate and hinder weight loss from pacients perspective].

    PubMed

    Lecaros-Bravo, Javiera; Cruzat-Mandich, Claudia; Díaz-Castrillón, Fernanda; Moore-Infante, Catalina

    2015-04-01

    Introducción: La obesidad se ha convertido en un problema de salud pública a nivel mundial. Asociado a esto, las cirugías bariátricas han ido en progresivo aumento, dada su efectividad en la baja de peso a corto plazo. Sin embargo, se ha visto que existe un alto porcentaje de reganancia de peso a partir del tercer año post cirugía y existen pocos estudios de seguimiento de estos pacientes. Objetivos: Describir los facilitadores y obstaculizadores de la pérdida de peso, desde la perspectiva de adultos que han sido sometidos a cirugía bariátrica. Métodos: Se utilizó un enfoque cualitativo, descriptivo, basado en la Teoría Fundamentada. Se realizaron entrevistas en profundidad y los datos se analizaron a través de codificación abierta. La muestra estuvo compuesta por 8 mujeres y 3 hombres adultos, intervenidos en clínicas privadas. Resultados: Se generaron cinco categorías de análisis: (1) variables que favorecen la pérdida de peso post cirugía bariátrica, (2) variables que dificultan la pérdida y mantención de peso post cirugía, (3) evaluación de los resultados de la cirugía bariátrica, (4) problematización de la obesidad, y (5) relación con la comida. Discusión: Los principales hallazgos indican que el fracaso y el éxito en la pérdida de peso post cirugía se encuentra asociado a la posibilidad de tener una red de apoyo emocional y social, así como a la posibilidad de comprender y modificar el rol de la comida como mecanismo de regulación emocional.

  2. Mini-mastoidectomía para anastomosis hipogloso-facial con sección parcial del nervio hipogloso

    PubMed Central

    Campero, Álvaro; Ajler, Pablo; Socolovsky, Mariano; Martins, Carolina; Rhoton, Albert

    2012-01-01

    Introducción: La anastomosis hipogloso-facial es la técnica de elección para la reparación de la parálisis facial cuando no se dispone de un cabo proximal sano del nervio facial. La técnica de anastomosis mediante fresado mastoideo y sección parcial del hipogloso minimiza la atrofia lingual sin sacrificar resultados a nivel facial. Método: La porción mastoidea del nervio facial transcurre por la pared anterior de la AM, a un promedio de 18+/-3 mm de profundidad respecto de la pared lateral. Se debe reconocer la cresta supramastoidea, desde la cual se marca una línea vertical paralela al eje mayor de la AM, 1 cm por detrás de la pared posterior del CAE El fresado se comienza desde la línea medio mastoidea hasta la pared posterior del CAE. Una vez encontrado el nervio facial en el tercio medio del canal mastoideo, el mismo es seguido hacia proximal y distal. Resultados: El abordaje descripto permite acceder al nervio facial intratemporal en su porción mastoidea, y efectuar un fresado óseo sin poner en riesgo al nervio o a estructuras vasculares cercanas. Se trata de un procedimiento técnicamente más sencillo que los abordajes amplios habitualmente utilizados al hueso temporal; no obstante su uso debe ser restringido mayormente a la anastomosis hipogloso-facial. Conclusión: Esta es una técnica relativamente sencilla, que puede ser reproducida por cirujanos sin mayor experiencia en el tema, luego de su paso por el laboratorio de anatomía. PMID:23596555

  3. Determinacion de periodos fundamentales del suelo mediante vibraciones ambientales en el municipio de Humacao, Puerto Rico

    NASA Astrophysics Data System (ADS)

    Cintron Aponte, Rommel

    La tecnica de Nakamura ha sido utilizada a nivel mundial para determinar periodos fundamentales del suelo. La tecnica consiste en calcular y graficar cocientes espectrales H/V de vibraciones ambientales registradas sobre el suelo. Mediciones de vibraciones ambientales fueron tomadas en 151 lugares dentro del municipio de Humacao, localizado al este de Puerto Rico. Los datos se procesaron utilizando espectros de Fourier y espectros de potencia. La tecnica fue validada al compararla con los resultados de cocientes espectrales H/V de registros de sismos debiles y tambien con una modelacion numerica realizada con datos de un ensayo "downhole". Las graficas de los cocientes espectrales H/V fueron divididas en casos y grupos, los cuales dependen de la facilidad para identificar el periodo fundamental pico y amplitudes en frecuencias menores de 1 Hz, respectivamente. Los resultados obtenidos con ambos espectros fueron comparados y se concluye que los mismos se complementan para proveer resultados mas confiables. Se crearon mapas de periodos fundamentales, factores de amplitud, isoperiodos y clasificacion sismica de sitio. Los mapas de isoperiodos fueron realizados en las zonas mas pobladas sobre depositos de suelo. El mapa de periodos fundamentales del suelo mostro buena correlacion con la geologia local. El mapa de clasificacion sismica derivado de periodos de sitio fue comparado con el mapa de clasificacion sismica derivado de barrenos geotecnicos. El mapa de clasificacion obtenido de periodos puede sobreestimar un poco algunas clasificaciones del suelo. Sin embargo, este mapa puede proveer un estimado aproximado de la velocidad de onda de corte promedio del suelo hasta una profundidad de 100 pies (30 metros).

  4. PubMed

    Marzán-Rodríguez, Melissa; Varas-Díaz, Nelson

    2006-01-01

    El Virus de Inmunodeficiencia Humana (VIH) y el Síndrome de Inmunodeficiencia Adquirida (SIDA) han sido motivo de estigmatización para las personas que viven con ellos. Esta estigmatización se ha estudiado consecuentemente desde la perspectiva de opiniones de agentes estigmatizantes. Estas opiniones han obviado sistemáticamente el rol de las emociones en el proceso de estigmatización. Llevamos a cabo este estudio con el propósito de identificar el rol de las emociones en el proceso de estigmatización de las personas que viven con el virus (PVVS) por parte de profesionales de la salud. Para lograr este objetivo utilizamos un diseño exploratorio y cualitativo en el cual utilizamos la técnica de entrevistas semiestructuradas a profundidad. La muestra estuvo compuesta por 80 profesionales de la salud y estudiantes de las siguientes especialidades: psicología, trabajo social, medicina y enfermería. Los resultados reflejaron la existencia de emociones asociadas al VIH/SIDA tales como pena, lástima, compasión, asco, fobia y miedo entre los/as profesionales y estudiantes que participaron. Las personas participantes evidenciaron la necesidad de controlar sus emociones al interactuar con PVVS. Los resultados apuntan a la necesidad de explorar aquellos factores que mediatizan las emociones, tales como el contexto social en que se manifiestan y ante quiénes se revelan, para lograr entender a cabalidad el estigma que rodea al VIH/SIDA. PMID:20212916

  5. Microbial communities in the deep subsurface

    NASA Astrophysics Data System (ADS)

    Krumholz, Lee R.

    'énergie pour ces organismes vivant dans les fonds des océans peuvent être les dépôts sédimentaires océaniques. Dans cette revue, chacune des communautés microbiennes est discutée en détail en se référant spécifiquement à leurs sources d'énergie, au schéma observé de leur développement et à leur composition diversifiée. Cette information est donnée de façon critique dans le but d'améliorer la compréhension des processus géochimiques intervenant dans le sous-sol et de développer de nouvelles approches pour la dépollution souterraine. Resumen En este artículo se resume la diversidad de las poblaciones y comunidades microbianas en el subsuelo. A partir de exploraciones realizadas en el subsuelo, los científicos se están cuestionando en la actualidad aspectos relativos a la diversidad microbiana, las interacciones entre los distintos microorganismos y los mecanismos para el mantenimiento de las comunidades de microbios. Se ha comprobado la presencia de comunidades microbianas anaerobias y heterótrofas en areniscas relativamente permeables y en sedimentos arenosos ubicados cerca de depósitos ricos en materia orgánica, de la cual se alimentan. Algunas fuentes de material orgánico, que actúan como donantes de electrones, son: sedimentos del Eoceno ricos en lignito, bajo la planicie costera de Texas; pizarras del Cretácico ricas en materia orgánica, al sudoeste del país y arcillas cretácicas con materia orgánica y bacterias fermentativas, en la llanura Atlántica. También existen comunidades microbianas de gran diversidad en rocas ígneas, aunque la fuente de materia orgánica no es tan evidente. Algunos ejemplos son la subsuperficie del valle del Río Columbia, rico en basaltos, y las regiones graníticas de Suecia y Canadá. Estas comunidades microbianas subsuperficiales se mantienen por la acción de bacterias litotrópicas, que crecen en ambiente de H2, generado en la subsuperficie. También existen comunidades microbianas a gran profundidad

  6. Presentación del estudio "Links" de hombres que tienes sexo con hombres en Buenos Aires, Argentina.

    PubMed

    Carballo-Diéguez, Alex; Avila, María M; Balán, Iván C; Marone, Rubén; Pando, María A; Barreda, Victoria

    2011-03-01

    Estudios previos en Buenos Aires reportaron altas prevalencias de HIV entre HSH, con valores que oscilan entre 9 y 14% durante casi 10 años de continuo testeo. El objetivo principal de este estudio fue la evaluación de factores relacionados al comportamiento de alto riesgo para transmisión del HIV entre HSH entre los que se incluyen el conocimiento y factores emocionales, socioculturales y ambientales. Por otro lado se realizó la estimación de prevalencia e incidencia de HIV utilizando RDS (Respondent Driven Sampling), así como la presencia de otras infecciones de transmisión sexual. Por último se evaluaron los hábitos de testeo para HIV indagando que factores facilitan o impiden su realización. El estudio constó de dos fases, en primer lugar una fase cualitativa y posteriormente una fase cuantitativa con una duración total de 4 años y medio. Durante la fase cualitativa se realizaron 44 entrevistas individuales en profundidad, 8 grupos focales y 10 observaciones etnográficas (hoteles, baños públicos ("teteras"), cines pornográficos, fiestas privadas, dark rooms y discotecas). Durante la fase cuantitativa del estudio se realizó el reclutamiento de 500 participantes que provinieron de la Ciudad Autónoma de Buenos Aires, así como del Gran Buenos Aires. El reclutamiento se comenzó con 16 participantes llamados semillas. Se realizó el diagnóstico de infección por HIV, hepatitis B y C (HBV y HCV), Treponema pallidum, Virus Papiloma Humano (HPV) y Chlamidias. La colaboración establecida entre los grupos de trabajo enfocados en áreas diversas posibilitó el abordaje conjunto de nuevas estrategias de investigación antes no exploradas en nuestro país. Los resultados más relevantes de esta investigación serán progresivamente publicados en sucesivos números de Actualizaciones en SIDA.

  7. La preparacion en ciencia de los candidatos a maestros del nivel elemental primario segun la reforma de la educacion cientifica en Puerto Rico: Una propuesta de secuencia curricular

    NASA Astrophysics Data System (ADS)

    Rodriguez Plaza, Evelyn

    El proposito de esta investigacion fue identificar los componentes de la preparacion en ciencia que deben recibir los estudiantes del Bachillerato en Artes en Educacion Elemental, Nivel Primario, de acuerdo a los documentos que dirigen la reforma de la educacion cientifica en Puerto Rico. Tambien, se identificaron los componentes de los cursos que forman parte de la preparacion en ciencia de estos estudiantes. Se compararon los componentes de la preparacion en ciencia y los componentes de los cursos para determinar congruencias y discrepancias. Con los datos recopilados se identificaron los componentes de los cursos de una secuencia curricular para la preparacion en ciencia de los candidatos a maestros del nivel elemental primario. La secuencia curricular que se propone en esta investigacion incluye cursos de contenido cientifico y de metodologia en la ensenanza de la ciencia disenados para satisfacer las necesidades de los candidatos. Se recomienda que en los procesos para el diseno, la implantacion y la evaluacion de estos cursos participen profesores de ciencia, profesores de educacion y maestros del nivel elemental primario. Todos los cursos de la secuencia curricular deben tener un enfoque constructivista. Las experiencias educativas que se incluyan en los cursos deben aspirar a desarrollar en los candidatos los atributos de la cultura cientifica y actitudes positivas hacia la ciencia y hacia la ensenanza de esta disciplina. El modelaje por parte de los profesores que ensenen los cursos de la secuencia curricular es fundamental en el desarrollo profesional de los candidatos. Se recomienda que en los cursos de contenido cientifico se estudien los conceptos y los conocimientos cientificos que forman parte del curriculo de Kindergarten a tercer grado de forma integrada y con una profundidad universitaria. Estos cursos deben tener un enfoque interdisciplinario e incluir el estudio de la naturaleza de la ciencia y un componente de laboratorio para desarrollar los

  8. Social Representations of Gynecologic Cancer Screening Assessment a Qualitative research on Ecuadorian women.

    PubMed

    Godoy, Yolanda; Godoy, Clara; Reyes, Juan

    2016-06-01

    The purpose of this work was to explore: knowledge, attitudes, and beliefs regarding gynecologic cancer screening on Ecuadorian women users of primary care facilities, to identify the social representations that users of health services make about these programs and their influence on the decision to undergo a screening. An exploratory and qualitative research design was held using focus groups and in-depth interviews for data collection. A narrative content analysis of the results was conducted. Women's knowledge on gynecological cancer screening was confusing. Most frequent misconceptions related to the pap smear were: the belief that it could be useful for detecting pregnancy, ovarian cysts or infections. Most of the participants stated that the pap smear procedure is a traumatic and painful experience. Regarding to mammography women said it was used for sick woman and this procedure by itself may cause cancer. El propósito de esta investigación fue explorar los conocimientos, actitudes y creencias respecto a los programas de detección del cáncer ginecológico entre usuarias de centros de atención primaria de salud para identificar las representaciones sociales que las usuarias de los servicios de salud elaboran acerca de estos programas y de los diferentes procedimientos que comprenden. El diseño de la investigación fue exploratorio y cualitativo, mediante grupos focales y entrevistas a profundidad, con el respectivo análisis narrativo e interpretativo del contenido. Se encontró conocimiento confuso acerca de los programas de tamizaje de cáncer ginecológico y dificultades asociadas a la realización de los procedimientos. Los significados más frecuentes acerca de los programas fueron: el uso de la citología cérvico-vaginal para detectar embarazo, quistes ováricos o infecciones. La mayoría de los participantes asociaba este procedimiento con una experiencia dolorosa y traumática. Respecto al autoexamen de mamas, lo calificaron como un masaje

  9. Presentación del estudio “Links” de hombres que tienes sexo con hombres en Buenos Aires, Argentina

    PubMed Central

    Carballo-Diéguez, Alex; Ávila, María M; Balán, Iván C.; Marone, Rubén; Pando, María A.; Barreda, Victoria

    2011-01-01

    Resumen Estudios previos en Buenos Aires reportaron altas prevalencias de HIV entre HSH, con valores que oscilan entre 9 y 14% durante casi 10 años de continuo testeo. El objetivo principal de este estudio fue la evaluación de factores relacionados al comportamiento de alto riesgo para transmisión del HIV entre HSH entre los que se incluyen el conocimiento y factores emocionales, socioculturales y ambientales. Por otro lado se realizó la estimación de prevalencia e incidencia de HIV utilizando RDS (Respondent Driven Sampling), así como la presencia de otras infecciones de transmisión sexual. Por último se evaluaron los hábitos de testeo para HIV indagando que factores facilitan o impiden su realización. El estudio constó de dos fases, en primer lugar una fase cualitativa y posteriormente una fase cuantitativa con una duración total de 4 años y medio. Durante la fase cualitativa se realizaron 44 entrevistas individuales en profundidad, 8 grupos focales y 10 observaciones etnográficas (hoteles, baños públicos (“teteras”), cines pornográficos, fiestas privadas, dark rooms y discotecas). Durante la fase cuantitativa del estudio se realizó el reclutamiento de 500 participantes que provinieron de la Ciudad Autónoma de Buenos Aires, así como del Gran Buenos Aires. El reclutamiento se comenzó con 16 participantes llamados semillas. Se realizó el diagnóstico de infección por HIV, hepatitis B y C (HBV y HCV), Treponema pallidum, Virus Papiloma Humano (HPV) y Chlamidias. La colaboración establecida entre los grupos de trabajo enfocados en áreas diversas posibilitó el abordaje conjunto de nuevas estrategias de investigación antes no exploradas en nuestro país. Los resultados más relevantes de esta investigación serán progresivamente publicados en sucesivos números de Actualizaciones en SIDA. PMID:25264397

  10. Use of black vulture (Coragyps atratus) in complementary and alternative therapies for cancer in Colombia: A qualitative study

    PubMed Central

    2012-01-01

    Background Although Coragyps atratus has been used as a traditional therapy for patients with cancer, the scientific literature does not contain enough information on how this therapy is used or the mechanisms that explain this therapeutic practice. Objectives To understand the methods of use and the reasons given by patients and caregivers for the use of Coragyps atratus in cancer treatment. Methods This study used a qualitative design based on twenty in-depth interviews of patients with cancer or caregivers of patients with the disease. The analysis of the text was based on an inductive thematic approach. Results Resistance to disease and immune enhancement are properties attributed to Coragyps atratus when used for cancer treatment. The most recommended method of use is fresh blood ingestion, and the associated mechanism of action is transfer of immune factors to the individual who consumes it. Conclusions Use of Coragyps atratus as a treatment for cancer is a popular alternative therapy in Colombia. More studies are needed to understand the clinical effects of this intervention in cancer patients. Spanish abstract Introducción Aunque Coragyps atratus se usa tradicionalmente como terapia para pacientes con cáncer, no existe suficiente información en la literatura científica sobre su forma de utilización ni sobre los mecanismos explicativos que subyacen a esta práctica terapéutica. Objetivos Conocer métodos de utilización y mecanismos explicativos dados por los pacientes y cuidadores de pacientes sobre el uso de Coragyps atratus en el tratamiento del cáncer. Materiales y métodos Diseño cualitativo basado en veinte entrevistas en profundidad de pacientes con cáncer o cuidadores de pacientes con esta enfermedad. Análisis de texto basado en enfoque temático inductivo. Resultados Al Coragyps atratus se le atribuyen propiedades de resistencia y fortalecimiento del sistema inmune de personas enfermas de cáncer. La forma de utilización mas común es la

  11. [Endocrinometabolic disorders in chronic obstructive pulmonary disease].

    PubMed

    Torres-Sánchez, Irene; Valenza, Marie Carmen; Carrasco, Fernando; Cabrera-Martos, Irene; Valenza-Demet, Gerald; Cano-Capellaci, Marcelo

    2013-01-01

    Introducción: La enfermedad pulmonar obstructiva crónica (EPOC) se caracteriza por obstrucción crónica del flujo aéreo y se asocia frecuentemente a alteraciones endocrino-metabólicas que empeoran la situación clínica del paciente y su pronóstico. El conocimiento en profundidad de estas alteraciones en los pacientes con EPOC permite llevar a cabo medidas preventivas, detección temprana e intervenciones nutricionales adecuadas. Objetivos: Analizar la prevalencia de comorbilidades endocrino-metabólicas en pacientes con EPOC y los factores de riesgo que favorecen la aparición de dichas enfermedades. Métodos: Se desarrolló una estrategia de búsqueda exhaustiva de la literatura limitada a los últimos diez años, en las bases de datos PubMed, Scopus y ScienceDirect, usando las palabras clave “endocrine metabolic disorders AND COPD”, “endocrine disorders AND COPD” y “metabolic disorders AND COPD”. ”. En el análisis bibliográfico se excluyeron aquellos artículos cuyo título o contenido no se correspondía con el objetivo del presente estudio, así como los artículos duplicados en las bases de datos. Finalmente, tras una profunda lectura crítica, fueron seleccionados y analizados 17 artículos. Resultados: El análisis de los artículos ha mostrado una relación significativa entre la EPOC y la presencia de alteraciones endocrino-metabólicas tales como diabetes mellitus, síndrome metabólico, obesidad, osteoporosis e hipogonadismo. Los autores coinciden en la alta prevalencia de estas comorbilidades, que influyen de forma diferente en el desarrollo de la EPOC. Conclusiones: Debido a la alta prevalencia y asociación con la EPOC, estas comorbilidades han de ser tenidas en cuenta por el profesional sanitario, ya que pueden afectar su abordaje, intervención y resultados.

  12. Social Representations of Gynecologic Cancer Screening Assessment a Qualitative research on Ecuadorian women.

    PubMed

    Godoy, Yolanda; Godoy, Clara; Reyes, Juan

    2016-06-01

    The purpose of this work was to explore: knowledge, attitudes, and beliefs regarding gynecologic cancer screening on Ecuadorian women users of primary care facilities, to identify the social representations that users of health services make about these programs and their influence on the decision to undergo a screening. An exploratory and qualitative research design was held using focus groups and in-depth interviews for data collection. A narrative content analysis of the results was conducted. Women's knowledge on gynecological cancer screening was confusing. Most frequent misconceptions related to the pap smear were: the belief that it could be useful for detecting pregnancy, ovarian cysts or infections. Most of the participants stated that the pap smear procedure is a traumatic and painful experience. Regarding to mammography women said it was used for sick woman and this procedure by itself may cause cancer. El propósito de esta investigación fue explorar los conocimientos, actitudes y creencias respecto a los programas de detección del cáncer ginecológico entre usuarias de centros de atención primaria de salud para identificar las representaciones sociales que las usuarias de los servicios de salud elaboran acerca de estos programas y de los diferentes procedimientos que comprenden. El diseño de la investigación fue exploratorio y cualitativo, mediante grupos focales y entrevistas a profundidad, con el respectivo análisis narrativo e interpretativo del contenido. Se encontró conocimiento confuso acerca de los programas de tamizaje de cáncer ginecológico y dificultades asociadas a la realización de los procedimientos. Los significados más frecuentes acerca de los programas fueron: el uso de la citología cérvico-vaginal para detectar embarazo, quistes ováricos o infecciones. La mayoría de los participantes asociaba este procedimiento con una experiencia dolorosa y traumática. Respecto al autoexamen de mamas, lo calificaron como un masaje

  13. [Food insecurity among elderly people in 15 districts of the Great Santiago area; an unresolved issue].

    PubMed

    Vargas Puello, Vianny; Alvarado Orellana, Sergio; Atalah Samur, Eduardo

    2013-01-01

    Introducción: Experimentar inseguridad alimentaria determina consecuencias negativas en la nutrición, salud y bienestar general de los adultos mayores y sus familias. En Chile prácticamente no existe información al respecto, a pesar de ser un importante problema de salud pública en otros países de la región. Objetivos: Determinar la prevalencia de inseguridad alimentaria y su relación con factores sociodemográficos, económicos y nutricionales en Adultos Mayores residentes en comunas del nivel socioeconómico medio-bajo y bajo del Gran Santiago. Materiales y métodos: Estudio observacional transversal en 344 adultos mayores de 65 a 74 años; encuesta socioeconómica, demográfica, nutricional y de inseguridad alimentaria en el hogar (HFIAS). Se determinó prevalencia de inseguridad alimentaria y su relación con las variables independientes por modelos de regresión logística multivariados. Resultados: El 40,4% de muestra presentaba inseguridad alimentaria (95% IC 35,2-45,6%), predominantemente de tipo leve, con una proporción mayor en mujeres, en el límite de la significación estadística. La probabilidad de percibir inseguridad alimentaria se asoció significativamente con bajos ingresos familiares (OR 4,2 IC 2,1-8,6), con mayor número de personas en el hogar (OR 2,4), malnutrición por déficit o exceso (OR 2,0), no ser propietario de la vivienda (OR 2,0) y menores ingresos personales (OR 1,8). Conclusiones: Existe una alta prevalencia de inseguridad alimentaria en esta población, la que se asocia con variables sociodemográficas, económicas y nutricionales. La seguridad alimentaria es un importante tema de salud pública y nutrición en el país, que debe ser investigado en mayor profundidad.

  14. Fluid intake in Spanish children and adolescents; a cross-sectional study.

    PubMed

    Fenández-Alvira, Juan Miguel; Iglesia, Iris; Ferreira-Pêgo, Cíntia; Babio, Nancy; Salas-Salvadó, Jordi; Moreno, Luis A

    2014-05-01

    Introducción: Diversos estudios han mostrado que el proceso de deshidratación tiene lugar en población infantil y adolescente, y por ello, son causa de preocupación. Sin embargo, los patrones de consumo de líquidos en poblaciones infantil y adolescente no han sido estudiados en profundidad. Objetivos: Evaluar la ingesta de líquidos total a partir de distintos tipos de bebidas en niños y adolescentes españoles. Métodos: Un total de 238 niños y adolescentes de entre 3 y 17 años de edad fueron reclutados aleatoriamente en las distintas regiones españolas. La información sobre la cantidad y calidad de la ingesta diaria de líquidos se recogió mediante un registro de 24 horas específico para la evaluación de fluidos durante 7 días consecutivos. Results: La ingesta de líquidos estuvo por debajo del 80% de las recomendaciones de la EFSA en el 87% de la población de estudio. En el presente estudio el agua fue la principal fuente de líquidos, seguida de la leche y derivados y de las bebidas azucaradas. No se encontraron diferencias significativas en los patrones de consumo entre géneros. El consumo de bebidas calientes, bebidas azucaradas y edulcoradas incrementó con la edad, mientras que el consumo de leche y derivados disminuyó. Conclusion: La gran mayoría de nuestra población no cumplió con las recomendaciones de la EFSA sobre la ingesta total de agua. Por ello, se debería promover un aumento en el consumo de agua en niños y adolescentes, para poder satisfacer las necesidades de líquidos sin aumentar la ingesta calórica.

  15. Presentación del estudio "Links" de hombres que tienes sexo con hombres en Buenos Aires, Argentina.

    PubMed

    Carballo-Diéguez, Alex; Avila, María M; Balán, Iván C; Marone, Rubén; Pando, María A; Barreda, Victoria

    2011-03-01

    Estudios previos en Buenos Aires reportaron altas prevalencias de HIV entre HSH, con valores que oscilan entre 9 y 14% durante casi 10 años de continuo testeo. El objetivo principal de este estudio fue la evaluación de factores relacionados al comportamiento de alto riesgo para transmisión del HIV entre HSH entre los que se incluyen el conocimiento y factores emocionales, socioculturales y ambientales. Por otro lado se realizó la estimación de prevalencia e incidencia de HIV utilizando RDS (Respondent Driven Sampling), así como la presencia de otras infecciones de transmisión sexual. Por último se evaluaron los hábitos de testeo para HIV indagando que factores facilitan o impiden su realización. El estudio constó de dos fases, en primer lugar una fase cualitativa y posteriormente una fase cuantitativa con una duración total de 4 años y medio. Durante la fase cualitativa se realizaron 44 entrevistas individuales en profundidad, 8 grupos focales y 10 observaciones etnográficas (hoteles, baños públicos ("teteras"), cines pornográficos, fiestas privadas, dark rooms y discotecas). Durante la fase cuantitativa del estudio se realizó el reclutamiento de 500 participantes que provinieron de la Ciudad Autónoma de Buenos Aires, así como del Gran Buenos Aires. El reclutamiento se comenzó con 16 participantes llamados semillas. Se realizó el diagnóstico de infección por HIV, hepatitis B y C (HBV y HCV), Treponema pallidum, Virus Papiloma Humano (HPV) y Chlamidias. La colaboración establecida entre los grupos de trabajo enfocados en áreas diversas posibilitó el abordaje conjunto de nuevas estrategias de investigación antes no exploradas en nuestro país. Los resultados más relevantes de esta investigación serán progresivamente publicados en sucesivos números de Actualizaciones en SIDA. PMID:25264397

  16. Groundwater contamination in the basement-complex area of Ile-Ife, southwestern Nigeria: A case study using the electrical-resistivity geophysical method

    NASA Astrophysics Data System (ADS)

    Adepelumi, A. A.; Ako, B. D.; Ajayi, T. R.

    2001-11-01

    chantillons d'eau ont été prélevés à une profondeur de 5,0 m dans 20 puits tests et analysés pour la qualité. Les concentrations en Cr, Cd, Pb, Zn et Cu sont légèrement au-dessus des valeurs recommandées par l'OMS. Des panaches d'eau contaminée provenant de bassins d'eaux usées ont été délimités. Les profils géoélectriques mettent en évidence quatre couches, qui sont successivement en profondeurs croissantes une argile latéritique, un sable ou un sable argileux, le substratum altéré, puis fissuré, et enfin le substratum non altéré. Les niveaux 3 et 4 les plus profonds constituent l'aquifère principal, de 3,1-67,1 m d'épaisseur. La distribution des éléments dans les effluents d'égouts confirme l'existence d'une communication hydrologique entre les bassins d'épandage et la nappe. Les eaux souterraines sont contaminées, comme le prouvent les résultats des prélèvements et de la géophysique. Par conséquent, les résultats démontrent la fiabilité de la méthode géophysique de résistivité électrique pour la détection et la cartographie de panaches de pollution dans un environnement de socle cristallin. Resumen. Se ha efectuado un estudio hidrogeológico ambiental en el punto de vertido de las aguas residuales del Campus Universitario de Obafemi Awolowo, en Ile-Ife (Nigeria). El objetivo era determinar la validez del método de la resistividad eléctrica para delimitar penachos de contaminación en un medio rocoso. Se utilizó 50 estaciones con un Terrameter ABEM SAS 300C, utilizando la matriz de Wenner. Se interpretó los resultados por medio de una técnica iterativa automática. Se recogieron muestras de agua a una profundidad de 5 m en 20 pozos de ensayo, las cuales fueron posteriormente analizadas en laboratorio. Las concentraciones de cromo, cadmio, plomo, cinc y cobre son ligeramente superiores a los valores guía de la Organización Mundial de la Salud. Se delineó el penacho de agua contaminada procedente de las balsas de aguas

  17. Hydrology of the coastal sabkhas of Abu Dhabi, United Arab Emirates

    NASA Astrophysics Data System (ADS)

    Sanford, Ward; Wood, Warren

    2001-05-01

    10 km de long et de 10 m d'épaisseur, indiquent qu'environ 1 m3/an d'eau entre et sort par écoulement souterrain latéral, que 40 à 50 m3/an entrent par drainance ascendante, et que 640 m3/an pénètrent par recharge à partir de la pluie. À partir des flux estimés d'eau et de solutés pour la drainance ascendante dans la sebkha, 7 à 8 volumes de pores de saumure sont entrés par en bas dans la sebkha depuis le moment où la sebkha est devenue saturée, il y a 7.000 ans, du fait de la dernière remontée du niveau marin. Resumen. Se ha estimado el flujo de agua y se ha efectuado un balance de agua en la superficie del terreno y en una sección superficial de 10 m de profundidad de los sabkhasAmbiente de sedimentación costera que se caracteriza por: (1) sus condiciones de aridez o semi-aridez por encima del nivel de mareas altas y (2) la ausencia de vegetación. Son habituales las evaporitas, depósitos eólicos y depósitos de inundación de marea. costeros cercanos a la ciudad de Abu Dhabi (Emiratos Árabes Unidos), al este de la frontera con Arabia Saudí. La estimación de los flujos se ha hecho con base en los niveles y conductividades hidráulicas medidos en pozos, y en las tasas de evaporación medidas mediante una cámara de humedad. Contrariamente a los modelos conceptuales propuestos en estudios previos, se ha estimado que la entrada de agua subterránea es pequeña, mientras que las componentes principales del balance son la recarga de agua de lluvia y la evaporación desde el nivel freático. Las estimaciones hechas en un volumen de sabkha de 1 m de anchura por 10 km de longitud y 10 m de profundidad indican que alrededor de 1 m3/a de agua entra y sale por flujo subterráneo lateral, 40-50 m3/a lo hacen por recarga desde niveles inferiores, y 650 m3/a proceden de la recarga de agua de lluvia. Teniendo en cuenta la estimación del flujo de agua y solutos para la recarga desde los niveles inferiores, se calcula que entre 7 y 8 vol

  18. Groundwater flow and geochemistry in the lower reaches of the Yellow River: a case study in Shandang Province, China

    NASA Astrophysics Data System (ADS)

    Chen, J. Y.; Tang, C. Y.; Sakura, Y.; Kondoh, A.; Shen, Y. J.

    2002-08-01

    é par la signature isotopique, qui a alors été utilisée pour calculer les contributions des trois sources: la pluie, l'eau ancienne et l'eau prélevée dans le fleuve, avec un taux moyen de mélange respectivement de 18, 17 et 65%. Comme indicateur de l'écoulement de l'eau, la concentration en Cl- varie dans une large gamme, dans un profil de 30 cm à 10 m en profondeur, avec une concentration maximale à une profondeur d'environ 1,2 m. Les concentrations sont relativement stables à partir de 2 m, profondeur de la limite entre les zones non saturée et saturée. On a ainsi montré que l'eau du Fleuve Jaune est prédominante dans le mélange, au sein de l'aquifère en termes d'écoulement de la nappe et de composition chimique. Resumen. Se ha recogido muestras de agua del Río Amarillo y de pozos para obtener medidas químicas e isotópicas en los condados de Yucheng y Qihe, que se abastecen con 6-9×108 m3 anuales de aguas de dicho río. Hay una zona de conductividad eléctrica (CE) elevada en las aguas subterráneas, la cual se corresponde bien a escala regional con una divisoria en el nivel piezométrico que representa la vía principal de flujo a través de la región, pero con un gradiente bajo. La zona de mayor CE a lo largo de la divisoria está localizada en el punto con la menor cota topográfica en el ámbito de estudio. La característica principal de las aguas subterráneas es la relación lineal que existe entre los aniones principales como resultado de un proceso de mezcla. Este efecto se confirma mediante la huella isotópica, que se utilizó para calcular las contribuciones de tres orígenes distintos: precipitación, aguas antiguas y aguas derivadas del río, obteniéndose porcentajes respectivos del 18, 17, y 65%. Como trazador del agua, la concentración de cloruro varía ampliamente en el perfil del suelo de 0,3-10 m, con un máximo a una profundidad aproximada de 1,2 m. Las concentraciones son relativamente estables hacia 2 m de profundidad, que

  19. Exploration of an alluvial aquifer in Oman by time-domain electromagnetic sounding

    NASA Astrophysics Data System (ADS)

    Young, M. E.; de Bruijn, R. G. M.; Al-Ismaily, A. Salim

    sont grossièrement caractérisés par des différentes gammes de résistivitéélectrique se recouvrant, dépendant surtout de la teneur en argiles et du degré de cimentation. Les résistivités près de la côte diminuent du fait de l'intrusion marine. Ces variations de résistivité ont été cartographiées à partir de 400km de profils électromagnétiques, dans le domaine temporel ; trois zones ont été distinguées dans l'aquifère alluvial. Le biseau salé a aussi été délimité, jusqu'à 10km de la côte. L'épaisseur de la partie saturée des graviers va de 20-160m sur une étendue supérieure à 600km2. Resumen Un tercio de la población de Omán depende de las aguas subterráneas extraídas del aluvial de la Llanura de Batinah, en la costa del Golfo de Omán. Para determinar la profundidad y naturaleza del aluvial, así como los límites del acuífero, se han usado técnicas de exploración geofísica profunda. El basamento y los límites estructurales del aluvial en su contacto con los sedimentos marinos del Terciario y la ofiolita cretácica se obtuvieron mediante sísmica de reflexión, registrada previamente en campañas de exploración petrolífera. La base del aluvial buza hacia el norte desde el pie de las Montañas del Norte de Omán, alcanzando una profundidad máxima de 2000m en la costa. Las distintas facies del aluvial están caracterizadas por rangos distintos, pero superpuestos, de resistividad eléctrica, dependiendo del contenido en arcillas y del grado de cementación. Las resistividades cerca de la costa se reducen por la intrusión salina. Estas variaciones de resistividad se obtuvieron con registros electromagnéticos a lo largo de un perfil de 400km, con el objetivo de distinguir las tres zonas del acuífero aluvial. También se pudo obtener la geometría de la cuña de intrusión, que llega hasta 10km de la costa. El espesor de las gravas saturadas que forman el acuífero oscila entre los 20-160m en un área superior a 600km2.

  20. Hydrology of the coastal sabkhas of Abu Dhabi, United Arab Emirates

    NASA Astrophysics Data System (ADS)

    Sanford, Ward; Wood, Warren

    2001-05-01

    10 km de long et de 10 m d'épaisseur, indiquent qu'environ 1 m3/an d'eau entre et sort par écoulement souterrain latéral, que 40 à 50 m3/an entrent par drainance ascendante, et que 640 m3/an pénètrent par recharge à partir de la pluie. À partir des flux estimés d'eau et de solutés pour la drainance ascendante dans la sebkha, 7 à 8 volumes de pores de saumure sont entrés par en bas dans la sebkha depuis le moment où la sebkha est devenue saturée, il y a 7.000 ans, du fait de la dernière remontée du niveau marin. Resumen. Se ha estimado el flujo de agua y se ha efectuado un balance de agua en la superficie del terreno y en una sección superficial de 10 m de profundidad de los sabkhasAmbiente de sedimentación costera que se caracteriza por: (1) sus condiciones de aridez o semi-aridez por encima del nivel de mareas altas y (2) la ausencia de vegetación. Son habituales las evaporitas, depósitos eólicos y depósitos de inundación de marea. costeros cercanos a la ciudad de Abu Dhabi (Emiratos Árabes Unidos), al este de la frontera con Arabia Saudí. La estimación de los flujos se ha hecho con base en los niveles y conductividades hidráulicas medidos en pozos, y en las tasas de evaporación medidas mediante una cámara de humedad. Contrariamente a los modelos conceptuales propuestos en estudios previos, se ha estimado que la entrada de agua subterránea es pequeña, mientras que las componentes principales del balance son la recarga de agua de lluvia y la evaporación desde el nivel freático. Las estimaciones hechas en un volumen de sabkha de 1 m de anchura por 10 km de longitud y 10 m de profundidad indican que alrededor de 1 m3/a de agua entra y sale por flujo subterráneo lateral, 40-50 m3/a lo hacen por recarga desde niveles inferiores, y 650 m3/a proceden de la recarga de agua de lluvia. Teniendo en cuenta la estimación del flujo de agua y solutos para la recarga desde los niveles inferiores, se calcula que entre 7 y 8 vol

  1. High-pressure thermal aureoles around two Neoproterozoic synorogenic magmatic epidote-bearing granitoids, Northeastern Brazil

    NASA Astrophysics Data System (ADS)

    Caby, Renaud; Sial, Alcides N.; Ferreira, Valderez P.

    2009-02-01

    cerca de los contactos magmáticos y muestran lineaciones minerales casi verticales. Venillas leucocraticas contienen cuarzo, oligoclasa, granate, kyanita, estaurolita, rutilo e ilmenita sugiriendo que el límite en las condiciones de fusión fueron cercanas a los contactos magmáticos ( T ⩾ 650 °C, P entorno 8 kbar). Estos hornfelses de alta presión forman una cobertura rígida de poco metros entorno a los dos plutones. Contrariamente a lo conocido en diferentes ejemplos de hornfelses con kyanita con registro de descompresión, la isóbara de enfriamiento para cerca de 450 °C está controlada por el contenido de Si 3.20-3.30 de fengitas retrógradas, en los hornfelses internos y en las márgenes de los plutones donde las tonalitas están deformadas ductilmente. Isógradas y batógradas son, por lo tanto, aparentemente telescopadas debido a cizalla de alta presión/baja temperatura, posiblemente causado por subsecuentes movimientos verticales diferenciales afectando estos dos plutones solidificados. El emplazamiento a una profundidad inusual de estos plutones calci-alcalinos syn-cinemáticos es explicado por un modelo geodinámico tentativo que involucra un escenario de subducción pre-620 Ma.

  2. Water-gas dynamics and coastal land subsidence over Chioggia Mare field, northern Adriatic Sea

    NASA Astrophysics Data System (ADS)

    Teatini, Pietro; Baú, Domenico; Gambolati, Giuseppe

    2000-09-01

    menace potentielle pour la ville de Venise, à 25 km au nord-ouest du centre de Chioggia Mare. Afin d'évaluer le risque de subsidence du sol provoquée par les prélèvements de gaz, un modèle numérique a été développé pour prévoir la compaction des formations réservoirs de gaz en même temps que celle de l'aquifère latéral et sous-jacent, par effet de drainance, sur une période de 13 ans de production, suivie de 12 ans, et pour prévoir le transfert de la compaction profonde jusqu'à la surface du sol. Afin de prendre en compte l'incertitude sur un petit nombre de paramètres hydromécaniques importants, plusieurs scénarios ont été simulés et les prévisions les plus pessimistes ont été obtenues. Les résultats de la modélisation montrent qu'on doit s'attendre, au cours des 25 ans, au plus à une subsidence du sol de 1 cm à Chioggia, tandis que Venise ne subira aucun effet. Si la baisse de l'aquifère est compensée par une injection d'eau, la subsidence du sol s'arrêtera à 5 km au large et la zone côtière de Chioggia subira un effet de 0,6 à 0,7 cm. Resumen. Recientemente, la compañía nacional italiana del petróleo, ENI-Agip, ha enviado al Ministerio de Medio Ambiente de Italia (Comité VIA) un gran programa de desarrollo de 15 campos de gas en el norte del Mar Adriático para la evaluación de su impacto medioambiental. Una de las reservas principales de gas se halla en el mar de Chioggia, a unos 10 km mar adentro de la costa veneciana, a una profundidad de entre 1.000 y 1.400 m. Se espera que la producción en este campo produzca un impacto en la estabilidad de la línea de costa, y que suponga una amenaza potencial para la ciudad de Venecia, situada a 25 km al noroeste de la explotación. Se desarrolló un modelo numérico para evaluar el riesgo de subsidencia debido a la extracción de gas a lo largo de los 13 años de producción y del período post-productivo de 12 años. Sus predicciones indican que se causará la compactación tanto

  3. Approaches to optimal aquifer management and intelligent control in a multiresolutional decision support system

    NASA Astrophysics Data System (ADS)

    Orr, Shlomo; Meystel, Alexander M.

    2005-03-01

    por lo tanto, estocasticidad o aleatoriedad ha incrementado la profundidad y resaltado relaciones importantes entre la incertidumbre, confiabilidad, riesgo, y su efecto en la función de costo, la adición también ha permitido (a) introducir complejidad adicional que resulta en potencia computacional excesiva aún para un solo parámetro incierto/aleatorio; y (b) llevar a reconocer nuestra discapacidad para evaluar la incertidumbre completa aún cuando se incluyen todos los parámetros inciertos. Se introduce un cambio paradigmático: una adaptación de nuevos métodos de control de inteligencia que relajarála dependencia en PDE estocásticas, rígidas y de uso computacional intensivo, cambiando el énfasis hacia un sistema de apoyo de decisiones de propósitos múltiples (MRDS) adaptivo, flexible, y orientadoa objetivos con fuerte aprendizaje sin supervisión (orientado a la anticipación más que a la predicción) con fuerte capacidad de optimización eficiente, lo cual podría aportar las soluciones necesarias a los problemas de manejo reales con los acuíferos. El artículo resalta los vínculos entre desarrollos pasados y control/planificación/optimización futura de sistemas hidrogeológicos.

  4. Dual-porosity modeling of groundwater recharge: testing a quick calibration using in situ moisture measurements, Areuse River Delta, Switzerland

    NASA Astrophysics Data System (ADS)

    Alaoui, Abdallah; Eugster, Werner

    sensitivité ont montré que l'investigation de la couverture du sol est suffisante pour l'estimation locale de la RN du fait que l'eau traversant le plan du flux nul se trouverait sous la zone des racines et échapperait à l'évapotranspiration. La RN simulée sur les 0.70 m du sol sous les conditions d'équilibre était de 364 mm, ce qui est comparable aux mesures. Se propone un método sencillo para calibrar el modelo de doble porosidad "MACRO" mediante medidas in-situ obtenidas por TDR durante un breve ensayo de infiltración (2,8 horas), con el objetivo de estimar la recarga local al acuífero. Ésta ha sido modelada de dos formas: considerando los 3 m de suelo no saturado y empleando sólo desde la capa superior hasta el plano de flujo nulo (de 0 a 0,70 m). Se compara la recarga modelada con la recarga local medida en campo, la cual fue de 313 mm durante un ciclo anual (del 15 de octubre de 1990 al 15 de octubre de 1991). Las mejores simulaciones corresponden a la hipótesis de columna entera no saturada en condiciones de equilibrio, excluyendo el efecto de macroporos (valor de 330 mm), mientras que el resultado obtenido para condiciones de no equilibrio en la recarga local está sobreestimado (378 mm). Los análisis de sensibilidad muestran que la investigación del horizonte superior del suelo es suficiente para estimar la recarga local en este caso, ya que el agua almacenada por debajo de esta profundidad parece estar fuera del alcance típico de las raíces de la vegetación y no puede ser evapotranspirada. La recarga modelada en condiciones de equilibrio para la capa superior de 0,70 m de espesor es de 364 mm, valor aceptable respecto a las medidas.

  5. Water-resources reconnaissance of Île de la Gonâve, Haiti

    NASA Astrophysics Data System (ADS)

    Troester, Joseph W.; Turvey, Michael D.

    'analyse des reconnaissances de terrain indique que les eaux souterraines à l'intérieur de l'île sont de faciès bicarbonaté calcique, tandis que l'eau près de la côte a un faciès chloruré sodique dépassant les valeurs recommandées par l'OMS pour le sodium et les chlorures. Des tests pour la présence de bactéries productrices d'hydrogène sulfuré se sont révélés négatifs dans la plupart des forages, mais positifs dans la plupart des sources captées et tous les autres sources, bassins de grottes et puits creusés à la main, ce qui indique une contamination bactérienne de la plupart des sources d'eau. Du fait des difficultés pour s'approvisionner en eau douce, les 110.000 habitants utilisent en moyenne seulement 7 L par personne et par jour. La Isla de la Gonavê, cercana a la costa de Haití, tiene 750 km2. La profundidad al nivel freático está comprendida entre menos de 30 m para las calcitas del Eoceno y Mioceno Superior y más de 60 m en el acuífero de calcitas cuaternarias, el cual posee 300 m de espesor. La precipitación anual varía entre 800-1.400 mm, si bien la mayor parte se pierde por evapotranspiración y prácticamente no hay aguas superficiales. Según un balance de masas de cloruros, alrededor del 4% de la precipitación recarga el acuífero kárstico. Las cavidades y manantiales son una fuente habitual de agua. Los pozos excavados proporcionan agua en las áreas costeras. Pocos pozos productivos se han perforado a más de 60 m. El reconocimiento de los análisis de campo indica que las aguas subterráneas son de tipo bicarbonatado-cálcico en el interior, mientras que es de tipo clorurado-sódico en la costa, donde se sobrepasan las concentraciones recomendadas por la Organización Mundial de la Salud para sodio y cloruro. Los ensayos efectuados para detectar la presencia de bacterias productoras de sulfuro de hidrógeno resultaron negativos en la mayoría de los pozos perforados, pero fueron positivos en la muchos manantiales explotados

  6. Water-resources reconnaissance of Île de la Gonâve, Haiti

    NASA Astrophysics Data System (ADS)

    Troester, Joseph W.; Turvey, Michael D.

    'analyse des reconnaissances de terrain indique que les eaux souterraines à l'intérieur de l'île sont de faciès bicarbonaté calcique, tandis que l'eau près de la côte a un faciès chloruré sodique dépassant les valeurs recommandées par l'OMS pour le sodium et les chlorures. Des tests pour la présence de bactéries productrices d'hydrogène sulfuré se sont révélés négatifs dans la plupart des forages, mais positifs dans la plupart des sources captées et tous les autres sources, bassins de grottes et puits creusés à la main, ce qui indique une contamination bactérienne de la plupart des sources d'eau. Du fait des difficultés pour s'approvisionner en eau douce, les 110.000 habitants utilisent en moyenne seulement 7 L par personne et par jour. La Isla de la Gonavê, cercana a la costa de Haití, tiene 750 km2. La profundidad al nivel freático está comprendida entre menos de 30 m para las calcitas del Eoceno y Mioceno Superior y más de 60 m en el acuífero de calcitas cuaternarias, el cual posee 300 m de espesor. La precipitación anual varía entre 800-1.400 mm, si bien la mayor parte se pierde por evapotranspiración y prácticamente no hay aguas superficiales. Según un balance de masas de cloruros, alrededor del 4% de la precipitación recarga el acuífero kárstico. Las cavidades y manantiales son una fuente habitual de agua. Los pozos excavados proporcionan agua en las áreas costeras. Pocos pozos productivos se han perforado a más de 60 m. El reconocimiento de los análisis de campo indica que las aguas subterráneas son de tipo bicarbonatado-cálcico en el interior, mientras que es de tipo clorurado-sódico en la costa, donde se sobrepasan las concentraciones recomendadas por la Organización Mundial de la Salud para sodio y cloruro. Los ensayos efectuados para detectar la presencia de bacterias productoras de sulfuro de hidrógeno resultaron negativos en la mayoría de los pozos perforados, pero fueron positivos en la muchos manantiales explotados

  7. Spatial characteristics of groundwater temperature in the Ishikari Lowland, Hokkaido, northern Japan: analytical and numerical applications

    NASA Astrophysics Data System (ADS)

    Dim, J. R.; Sakura, Y.; Fukami, H.; Miyakoshi, A.

    2002-03-01

    éothermal profond. Entre les deux zones, le flux de chaleur est beaucoup plus faible. Afin de déterminer le rôle du flux d'eau souterraine dans la distorsion des isothermes dans cette zone, des analyses du gradient thermal en fonction de la température ont été réalisées elles ont permis de définir les composantes majeures du système aquifère régional. Une modélisation deux-dimensionnelle pour la simulation a ensuite contribué à la compréhension non seulement de la cause des variations horizontales du flux de chaleur dans cette région, mais également du contraste entre les propriétés des réservoirs superficiel et profond. Resumen. En los sedimentos porosos de las tierras bajas de Ishikari, hay un incremento gradual en el gradiente geotérmico desde el río Ishikari (3-4 °C 100 m-1) hacia la zona elevada del sudoeste (10 °C 100 m-1). Sin embargo, el gradiente geotérmico a profundidades someras difiere de la distribución de fondo. A pesar de las pérdidas por el flujo convectivo de calor asociadas generalmente al flujo de aguas subterráneas, el flujo de calor permanece elevado (100 mW m-2) en el área de recarga, hacia el sudoeste de la cuenca del Ishikari, la cual pertenece a un campo geotérmico activo. Al nordeste de las tierras bajas, el flujo de calor alcanza 140 mW m-2, probablemente por el flujo ascendente de agua procedente del campo geotérmico profundo. Entre ambas áreas, el flujo de calor es mucho menor. Para examinar el papel del flujo hidráulico en la distorsión de las isotermas de esta región, se ha comparado el gradiente térmico con la temperatura, con lo cual se ha podido definir los componentes mayoritarios del sistema de flujo de las aguas subterráneas. El uso de modelos bidimensionales ha servido para comprender no sólo del origen de las variaciones horizontales del flujo de calor en este campo, sino también el contraste entre las propiedades térmicas de los reservorios someros y profundos de aguas subterráneas.

  8. Accuracy of CFC groundwater dating in a crystalline bedrock aquifer: Data from a site in southern Sweden

    NASA Astrophysics Data System (ADS)

    Bockgård, Niclas; Rodhe, Allan; Olsson, K. A.

    des échantillons à la limite de détection. Pour tous les échantillons, la date de la recharge établie avec le CFC-11 est antérieure à la date établie avec le CFC-12. La différence entre les deux dates peut dépasser 20 ans et s'explique-probablement-par la dégradation du CFC-11. Les dates de recharge de la nappe mesurées au CFC-12 sont comprises entre 1945 et 1975, excepté pour un échantillon qui possède une concentration actuelle. Il n'est pas possible de tirer des conclusions concernant la direction des écoulements et la vitesse de l'eau souterraine. La comparaison entre CFC-12 et tritium montre que des échantillons pourraient être soit le résultat du mélange d'eaux d'âges différents, soit des échantillons non-mélangés. Dans le cas d'un mélange binaire, les rapports du mélange composant la concentration mesurée sont déterminés. L'approche par modèle de mélange peut être étendue à des traceurs additionnels. Precisión en la datación de aguas subterráneas utilizando CFC en un acuífero de rocas cristalinas: datos provenientes de un sitio al sur de Suecia. Se determinaron las concentraciones de clorofluorucarbonos (CFC-11, CFC-12, y CFC-113) y de tritio en aguas subterráneas alojadas en rocas cristalinas fracturadas de Finnsjön, Suecia. El objetivo específico consistió en investigar la precisión de la datación de aguas subterráneas con CFC en este tipo de ambiente, tomando en consideración la degradación potencial y la mezcla de agua. Las muestras de agua se tomaron a una profundidad de 42 m en tres pozos ubicados a lo largo de una línea de 800 m transversal a una zona de recarga y de zona de descarga local. En la mayoría de las muestras se encontró que la concentración de CFC-113 estuvo en el límite de detección. La edad que se estimó en todas las muestras para la recarga aparente en base a CFC-11 fue más joven que la edad proveniente de CFC-12, con una diferencia de más de 20 años para algunas muestras. Esta

  9. Hydrogeology of a fractured shale (Opalinus Clay): Implications for deep geological disposal of radioactive wastes

    NASA Astrophysics Data System (ADS)

    Gautschi, Andreas

    2001-01-01

    ême lorsque des fractures et des failles existaient dans certains des intervalles d'essais. Ces mesures sont conformes aux données hydrogéologiques tirées du recoupement des argiles à Opalinus par dix tunnels du Jura plissé du nord de la Suisse. Malgré une tectonique intense, peu de manifestations de faibles venues d'eau ont été rencontrées dans plus de 6600 m de tunnel. Toutes les venues d'eau se sont produites dans des sections de tunnel où le recouvrement est inférieur à 200 m. Les données hydrauliques sont en bon accord avec les données hydrochimiques et isotopiques de l'eau porale des argiles. En se basant sur le grand nombre de données hydrogéologiques, qui portent en partie sur les environnements géologiques particulièrement peu propices, on peut avancer que le transport advectif le long des failles et des fractures n'est pas un facteur susceptible de remettre en question le choix de l'argile à Opalinus comme roche hôte pour le stockage de déchets radioactifs en formation géologique profonde. Resúmen. Dentro del programa suizo de eliminación de residuos radiactivos de alta actividad, se está investigando la posibilidad de utilizar unos esquistos Jurásicos (Arcilla Opalina) como depósito geológico. Las observaciones efectuadas en pozos en arcilla y los resultados de un programa de estudio alemán sobre eliminación de residuos peligrosos han demostrado que, a profundidades de entre 10 y 30 m, la permeabilidad de la Arcilla Opalina decrece en varios órdenes de magnitud. Los ensayos hidráulicos realizados en sondeos más profundos (en intervalos situados a más de 300 m) proporcionaron conductividades hidráulicas inferiores a 10-12 m/s, pese a que algunos de los intervalos interceptaban juntas y fallas. Estas medidas son coherentes con los datos hidrogeológicos de las secciones de Arcilla Opalina existentes en 10 túneles del Jurásico Plegado, al norte de Suiza. A pesar de las fallas extensivas, apenas se hallaron indicios de entrada de

  10. A geochemical and geophysical approach to derive a conceptual circulation model of CO2-rich mineral waters: A case study of Vilarelho da Raia, northern Portugal

    NASA Astrophysics Data System (ADS)

    Marques, J. M.; Santos, Monteiro; Graça, R. C.; Castro, R.; Aires-Barros, L.; Mendes Victor, L. A.

    2001-11-01

    éologiques similaires, mais non identiques. Resumen. La región de Vilarelho-Chaves está situada en el Norte de Portugal, junto a la frontera con España. Se caracteriza por la existencia de aguas minerales calientes y frías enriquecidas en CO2, que descargan mediante manantiales y pozos. El artículo tiene como objetivo la actualización del modelo conceptual de flujo de las aguas frías de Vilarelho de Raia, que son ricas en CO2. Dichas aguas se han formado fundamentalmente por la interacción con el CO2 procedente del manto profundo, y son del tipo bicarbonatado sódico. Los valores de δ18O, δ2H y 3H indican que proceden de la infiltración de agua meteórica en la Montaña Larouco -al Noroeste de Vilarelho de Raia-, que circulan a poca profundidad en un medio formado por de rocas graníticas y se mueven hacia el área de Vilarelho de Raia. El modelo conceptual de flujo, basado en datos geoquímicos y geofísicos, indica que las aguas minerales calientes de Chaves (76 °C) y las frías de Vilarelho de Raia (17 °C), ambas enriquecidas en CO2, no deben ser consideradas como manifestaciones de un único sistema hidrogeológico, sino de dos similares.

  11. Hydraulic properties and scale effects investigation in regional rock aquifers, south-western Quebec, Canada

    NASA Astrophysics Data System (ADS)

    Nastev, M.; Savard, M. M.; Lapcevic, P.; Lefebvre, R.; Martel, R.

    This paper reports on the characterization of hydraulic properties of regional rock aquifers carried out within a groundwater resources assessment project in the St. Lawrence Lowlands of south-western Quebec. To understand the aquifer behavior at both the fracture level and at field scale, hydraulic investigations were carried out using various aquifer tests. The groundwater flow at the local scale is controlled mostly by the fracture system. Results of the constant-head injection tests show a weak decreasing trend of hydraulic conductivity with depth indicating that a major part of the groundwater flow occurs in the first meters of the rock sequence. At the regional scale, the equivalent porous media approach is applicable. The hydraulic conductivity measurements were correlated to the scale of the aquifer tests expressed with the investigated aquifer volume. A simple interpolation procedure for the hydraulic conductivity field was developed based on the distance between field measurements and the tested aquifer volumes. The regional distribution of the hydraulic conductivity for the major fractured aquifer units indicates that dolostone is the most permeable whereas sandstone and crystalline rocks are the least permeable units. Este artículo trata de la caracterización de las propiedades hidráulicas en acuíferos regionales rocosos, la cual se llevó a cabo dentro del proyecto de evaluación de los recursos de agua subterránea en St. Lawrence Lowlands al suroeste de Quebec. Para entender el comportamiento del acuífero tanto a nivel de fractura como a escala del campo, se ejecutaron investigaciones hidráulicas usando varias pruebas de acuífero. El flujo del agua subterránea a escala local está controlado principalmente por el sistema de fracturas. Los resultados de las pruebas de inyección con cabeza constante muestran una tendencia decreciente débil de la conductividad hidráulica con la profundidad, indicando que la mayor parte del flujo de agua

  12. Groundwater contamination in the basement-complex area of Ile-Ife, southwestern Nigeria: A case study using the electrical-resistivity geophysical method

    NASA Astrophysics Data System (ADS)

    Adepelumi, A. A.; Ako, B. D.; Ajayi, T. R.

    2001-11-01

    chantillons d'eau ont été prélevés à une profondeur de 5,0 m dans 20 puits tests et analysés pour la qualité. Les concentrations en Cr, Cd, Pb, Zn et Cu sont légèrement au-dessus des valeurs recommandées par l'OMS. Des panaches d'eau contaminée provenant de bassins d'eaux usées ont été délimités. Les profils géoélectriques mettent en évidence quatre couches, qui sont successivement en profondeurs croissantes une argile latéritique, un sable ou un sable argileux, le substratum altéré, puis fissuré, et enfin le substratum non altéré. Les niveaux 3 et 4 les plus profonds constituent l'aquifère principal, de 3,1-67,1 m d'épaisseur. La distribution des éléments dans les effluents d'égouts confirme l'existence d'une communication hydrologique entre les bassins d'épandage et la nappe. Les eaux souterraines sont contaminées, comme le prouvent les résultats des prélèvements et de la géophysique. Par conséquent, les résultats démontrent la fiabilité de la méthode géophysique de résistivité électrique pour la détection et la cartographie de panaches de pollution dans un environnement de socle cristallin. Resumen. Se ha efectuado un estudio hidrogeológico ambiental en el punto de vertido de las aguas residuales del Campus Universitario de Obafemi Awolowo, en Ile-Ife (Nigeria). El objetivo era determinar la validez del método de la resistividad eléctrica para delimitar penachos de contaminación en un medio rocoso. Se utilizó 50 estaciones con un Terrameter ABEM SAS 300C, utilizando la matriz de Wenner. Se interpretó los resultados por medio de una técnica iterativa automática. Se recogieron muestras de agua a una profundidad de 5 m en 20 pozos de ensayo, las cuales fueron posteriormente analizadas en laboratorio. Las concentraciones de cromo, cadmio, plomo, cinc y cobre son ligeramente superiores a los valores guía de la Organización Mundial de la Salud. Se delineó el penacho de agua contaminada procedente de las balsas de aguas

  13. Numerical modelling and hydrochemical characterisation of a fresh-water lens in the Belgian coastal plain

    NASA Astrophysics Data System (ADS)

    Vandenbohede, A.; Lebbe, L.

    2002-05-01

    ée de canal de marée est étudiée. L'évolution hydrochimique de la lentille d'eau douce est reconstituée, révélant que les principales réactions chimiques sont l'échange de cations, la dissolution de calcite et l'oxydation de matières organiques. La formation et l'évolution de la lentille d'eau douce sont modélisées en recourant à un modèle en deux dimensions de transport de soluté dépendant de la densité la sensibilité au drainage et les conductivités sont étudiées. Le niveau du drainage influence surtout la profondeur de la lentille d'eau douce, alors que le temps de formation de la lentille est surtout influencé par la conductivité. Resumen. La distribución de las aguas dulces y salinas en acuíferos costeros está influenciada por muchos procesos. Se ilustra la influencia de la heterogeneidad del medio y de la interferencia humana mediante acciones tales como la recuperación de terrenos en la llanura costera belga, donde, hacia el año 1200 D.C., se aprovechó un medio sometido a fluctuaciones mareales. La salinidad del acuífero, que fue invadido por agua salada, está siendo rebajada desde entonces. La distribución espacial de turba, arcilla, limo y arena influencia el flujo general y la distribución de agua dulce y salina, además de afectar el esquema de drenaje, y origina el desarrollo de lentejones de agua dulce. Se inspecciona la calidad del agua en y en torno a los lentejones de agua dulce bajo la cresta de un canal mareal invertido. Se reconstruye la evolución hidroquímica de los lentejones de agua dulce, proponiendo como reacciones principales el intercambio catiónico, la disolución de calcita y la oxidación de materia orgánica. Se modela la formación y evolución de los lentejones mediante un modelo bidimensional de transporte con densidad variable, y se estudia la sensibilidad del drenaje y de las conductividades. El nivel de drenaje influencia sobretodo la profundidad de los lentejones de agua dulce, mientras el tiempo

  14. Causes of sinks near Tucson, Arizona, USA

    NASA Astrophysics Data System (ADS)

    Hoffmann, John P.; Pool, Donald R.; Konieczki, A. D.; Carpenter, Michael C.

    éà 17,000m3 a été entraîné lors de la formation de ces entonnoirs. Treize tranchées ont été creusées à des profondeurs de 4 à 6m afin de caractériser les sédiments proches de la surface dans les zones avec et sans entonnoirs. Les sédiments situés à 2m environ sous la surface contiennent un fort pourcentage d'argile dispersée, dans les zones à entonnoirs. Dans les zones sans entonnoirs, la granulométrie des sédiments est constituée en fortes proportions de sables moyens à grossiers, moyennement à bien lités, qui remplissent probablement un ancien chenal. Des levés électromagnétiques montrent que l'association de silts et d'argiles dans les zones à entonnoirs possède une forte conductivitéélectrique, par comparaison avec les sables des zones sans entonnoirs. Les entonnoirs sont dus probablement à des processus, proches de la surface, d'érosion souterraine des sédiments constitués surtout de silts et d'argiles. Les fractures préexistantes résultent sans doute de la dessiccation ou de la tension se produisant lors des périodes d'abaissement de la nappe, liéà l'enfoncement du lit de la rivière au cours des cent dernières années ou même avant.1 Resumen Se ha detectado la formación de dolinas como resultado de la subsidencia que ha tenido lugar en las zonas agrícolas Condado de Pima, Arizona, EEUU. Estos colapsos han aparecido en depósitos aluviales a lo largo de la llanura de inundación del Río Santa Cruz y han hecho que las zonas agrícolas sean peligrosas e inadecuadas para su uso. Las más de 1700 dolinas aparecidas se agrupan a lo largo de dos bandas con dirección nor-noroeste, paralelas al río y a otros ejes de drenaje del llano. Se ha estimado un desplazamiento de 17.000metros cúbicos de sedimentos para formar estas dolinas. Se excavaron trece zanjas de entre 4 y 6metros para caracterizar los sedimentos más superficiales tanto en áreas colapsadas como no colapsadas. Por debajo de los dos metros de profundidad, los

  15. Hydrogeology of a fractured shale (Opalinus Clay): Implications for deep geological disposal of radioactive wastes

    NASA Astrophysics Data System (ADS)

    Gautschi, Andreas

    2001-01-01

    ême lorsque des fractures et des failles existaient dans certains des intervalles d'essais. Ces mesures sont conformes aux données hydrogéologiques tirées du recoupement des argiles à Opalinus par dix tunnels du Jura plissé du nord de la Suisse. Malgré une tectonique intense, peu de manifestations de faibles venues d'eau ont été rencontrées dans plus de 6600 m de tunnel. Toutes les venues d'eau se sont produites dans des sections de tunnel où le recouvrement est inférieur à 200 m. Les données hydrauliques sont en bon accord avec les données hydrochimiques et isotopiques de l'eau porale des argiles. En se basant sur le grand nombre de données hydrogéologiques, qui portent en partie sur les environnements géologiques particulièrement peu propices, on peut avancer que le transport advectif le long des failles et des fractures n'est pas un facteur susceptible de remettre en question le choix de l'argile à Opalinus comme roche hôte pour le stockage de déchets radioactifs en formation géologique profonde. Resúmen. Dentro del programa suizo de eliminación de residuos radiactivos de alta actividad, se está investigando la posibilidad de utilizar unos esquistos Jurásicos (Arcilla Opalina) como depósito geológico. Las observaciones efectuadas en pozos en arcilla y los resultados de un programa de estudio alemán sobre eliminación de residuos peligrosos han demostrado que, a profundidades de entre 10 y 30 m, la permeabilidad de la Arcilla Opalina decrece en varios órdenes de magnitud. Los ensayos hidráulicos realizados en sondeos más profundos (en intervalos situados a más de 300 m) proporcionaron conductividades hidráulicas inferiores a 10-12 m/s, pese a que algunos de los intervalos interceptaban juntas y fallas. Estas medidas son coherentes con los datos hidrogeológicos de las secciones de Arcilla Opalina existentes en 10 túneles del Jurásico Plegado, al norte de Suiza. A pesar de las fallas extensivas, apenas se hallaron indicios de entrada de

  16. Fracture hydraulic conductivity in the Mexico City clayey aquitard: Field piezometer rising-head tests

    NASA Astrophysics Data System (ADS)

    Vargas, Carlos; Ortega-Guerrero, Adrián

    éthode de Hvorslev et certains avec la méthode de Bouwer-Rice. Les résultats indiquent que la distribution de K' s'ajuste à des modèles de régression log-gaussiens. Les valeurs de K' les plus fréquentes dans les plaines de Chalco et de Texcoco sont entre 1E-09 et 1E-08 m/s, avec des moyennes similaires de 1.19E-09 et 1.7E-09 m/s respectivement, qui sont d'un ou deux ordres de grandeurs supérieures à la conductivité de la matrice. Dans la plaine de Mexico, la moyenne est proche d'un ordre de grandeur en moins, avec 2.6E-10 m/s. Ce contraste entre le K' mesuré et celui de la matrice est attribué à la présence de fractures dans les 25-40 m supérieurs, ce qui est en accord avec les études précédentes sur la migration de solutés au travers de l'imperméable. El acuífero principal del Área Metropolitana de la Ciudad de México está recubierto por un acuitardo regional lacustre, cuya conductividad hidráulica es fundamental para evaluar la protección natural de las aguas subterráneas contra los contaminantes presentes en superficie y su respuesta hidráulica. Este estudio analiza la distribución y variación de dicha conductividad en las llanuras de Chalco, Texcoco y Ciudad de México (tres de los seis lagos que existían al principio en la Cuenca de México) a partir de 225 ensayos de campo en piezómetros múltiples existentes, ubicados entre 2 y 85 m de profundidad. La interpretación de los ensayos se ha realizado mediante el método de Hvorslev y-algunos-el de Bouwer-Rice. Los resultados indican que la distribución de la conductividad se ajusta a modelos de regresión lognormales. Las frecuencias dominantes en las Llanuras de Chalco y Texoco están comprendidas entre 1-9 y 10-8 m/s, con medias de población similares de 1.19×10-9 y 1.70×10-9 m/s, respectivamente, que son dos órdenes de magnitud mayores que el valor de la matriz. En el Llano de México, la media es casi un orden de magnitud inferior (2.60×10-10 m/s). Se atribuye este contraste

  17. Causes of sinks near Tucson, Arizona, USA

    NASA Astrophysics Data System (ADS)

    Hoffmann, John P.; Pool, Donald R.; Konieczki, A. D.; Carpenter, Michael C.

    éà 17,000m3 a été entraîné lors de la formation de ces entonnoirs. Treize tranchées ont été creusées à des profondeurs de 4 à 6m afin de caractériser les sédiments proches de la surface dans les zones avec et sans entonnoirs. Les sédiments situés à 2m environ sous la surface contiennent un fort pourcentage d'argile dispersée, dans les zones à entonnoirs. Dans les zones sans entonnoirs, la granulométrie des sédiments est constituée en fortes proportions de sables moyens à grossiers, moyennement à bien lités, qui remplissent probablement un ancien chenal. Des levés électromagnétiques montrent que l'association de silts et d'argiles dans les zones à entonnoirs possède une forte conductivitéélectrique, par comparaison avec les sables des zones sans entonnoirs. Les entonnoirs sont dus probablement à des processus, proches de la surface, d'érosion souterraine des sédiments constitués surtout de silts et d'argiles. Les fractures préexistantes résultent sans doute de la dessiccation ou de la tension se produisant lors des périodes d'abaissement de la nappe, liéà l'enfoncement du lit de la rivière au cours des cent dernières années ou même avant.1 Resumen Se ha detectado la formación de dolinas como resultado de la subsidencia que ha tenido lugar en las zonas agrícolas Condado de Pima, Arizona, EEUU. Estos colapsos han aparecido en depósitos aluviales a lo largo de la llanura de inundación del Río Santa Cruz y han hecho que las zonas agrícolas sean peligrosas e inadecuadas para su uso. Las más de 1700 dolinas aparecidas se agrupan a lo largo de dos bandas con dirección nor-noroeste, paralelas al río y a otros ejes de drenaje del llano. Se ha estimado un desplazamiento de 17.000metros cúbicos de sedimentos para formar estas dolinas. Se excavaron trece zanjas de entre 4 y 6metros para caracterizar los sedimentos más superficiales tanto en áreas colapsadas como no colapsadas. Por debajo de los dos metros de profundidad, los

  18. Dinámica y crecimiento de los granos de polvo en la nebulosa protoplanetaria

    NASA Astrophysics Data System (ADS)

    de La Fuente Marcos, Carlos

    2001-06-01

    En el escenario estándar de la formación planetaria, los planetesimales (cuerpos de tamaño kilométrico) crecen a partir de granos de polvo, similares a los interestelares, embebidos en un disco gaseoso denominado nebulosa protoplanetaria. Durante esta etapa, los movimientos del gas pueden tener gran influencia en la dinámica y el crecimiento de los granos de polvo, dado que el flujo kepleriano del gas frena el movimiento de los mismos haciendo que caigan hacia el Sol, y la turbulencia inhibe la inestabilidad gravitacional de la capa de polvo. Aunque se acepta que los planetesimales fueron los elementos constituyentes de los planetas, todavía se desconoce cómo se produjo la formación de los mismos. Por esta razón, en los estudios más recientes, existe un renovado interés por comprender mejor la evolución de la capa de polvo inmersa en el disco gaseoso de la Nebulosa. El gas que fluye en el disco puede engendrar estructuras carentes de simetría axial, como por ejemplo ondas espirales y vórtices, a partir de gran variedad de mecanismos de excitación e inestabilidad. En 1995, Barge y Sommeria pusieron de manifiesto que la existencia de vórtices gaseosos persistentes en la nebulosa solar tendría importantes consecuencias sobre la formación de los planetesimales y el posterior crecimiento de los planetas gigantes. La investigación desarrollada en esta Tesis analiza la relación entre el polvo y el gas debida al acoplamiento por fricción dinámica entre ambos; en concreto, se estudia el efecto del flujo medio del gas sobre la dinámica de las partículas de polvo. El primer objetivo es investigar en profundidad los procesos de captura y crecimiento de los granos de polvo dentro de un vórtice y su posible relevancia en cuanto a la formación de los planetesimales. El segundo objetivo es la exploración de los efectos de ondas espirales propagándose en el disco gaseoso sobre la dinámica y el crecimiento de las partículas. La presencia de líneas de

  19. Approaches to optimal aquifer management and intelligent control in a multiresolutional decision support system

    NASA Astrophysics Data System (ADS)

    Orr, Shlomo; Meystel, Alexander M.

    2005-03-01

    por lo tanto, estocasticidad o aleatoriedad ha incrementado la profundidad y resaltado relacion

  20. Hydrodynamic characteristics of the western Doñana Region (area of El Abalario), Huelva, Spain

    NASA Astrophysics Data System (ADS)

    Trick, Thomas; Custodio, Emilio

    eucaliptus en la década de 1950 y el uso más reciente de los acuíferos para riego y para abastecimiento de centros turísticos costeros han modificado el sistema de flujo del agua subterránea en esta zona. Este estudio se ha realizado en el sector occidental, llamado El Abalario. Se trata de una elevación suave situada entre el océano Atlántico y el arroyo de La Rocina. Debajo de un manto variable de arenas eólicas, que forma un alto cordón dunar costero, se encuentran sedimentos detríticos plio-cuaternarios formados por arenas silíceas finas, que hacia la base incluyen una capa de arenas gruesas y gravas de origen deltrico, los que a su vez yacen sobre margas. El flujo de agua subterránea está relacionado con niveles de gravas y gravillas semiconfinadas por las arenas fluvio-marinas que contienen el nivel freático. El nivel freático es somero excepto debajo del cordón dunar. Son frecuentes pequeñas lagunas temporales. Se ha simulado el flujo de agua subterránea en una sección para comprobar el modelo de flujo conceptual y la sensibilidad a variaciones de los parámetros. El modelo fue calibrado usando los valores de los parámetros hidráulicos obtenidos en ensayos de bombeo y datos piezométricos medidos a diferentes profundidades, y la descarga estimada al arroyo de La Rocina. La recarga de agua subterránea drena lateralmente, por un lado hacia la costa y por otro lado a través del arroyo de La Rocina, o directamente hacia las Marismas de Doñana situadas en el delta del río Guadalquivir. Con una lluvia media anual entre 550 y 600 mm, la recarga neta media estacionaria anual del acuífero, considerando periodos de tiempo largos, se estima entre 100 y 200 mm en las zonas de vegetación autóctona, y es notablemente menor en las zonas de plantación de eucaliptos. El modelo transitorio indica que la recarga varia espacialmente y no es claramente proporcional a la precipitación para periodos de un año. La evapotranspiración freática varia

  1. Accuracy of CFC groundwater dating in a crystalline bedrock aquifer: Data from a site in southern Sweden

    NASA Astrophysics Data System (ADS)

    Bockgård, Niclas; Rodhe, Allan; Olsson, K. A.

    des échantillons à la limite de détection. Pour tous les échantillons, la date de la recharge établie avec le CFC-11 est antérieure à la date établie avec le CFC-12. La différence entre les deux dates peut dépasser 20 ans et s'explique-probablement-par la dégradation du CFC-11. Les dates de recharge de la nappe mesurées au CFC-12 sont comprises entre 1945 et 1975, excepté pour un échantillon qui possède une concentration actuelle. Il n'est pas possible de tirer des conclusions concernant la direction des écoulements et la vitesse de l'eau souterraine. La comparaison entre CFC-12 et tritium montre que des échantillons pourraient être soit le résultat du mélange d'eaux d'âges différents, soit des échantillons non-mélangés. Dans le cas d'un mélange binaire, les rapports du mélange composant la concentration mesurée sont déterminés. L'approche par modèle de mélange peut être étendue à des traceurs additionnels. Precisión en la datación de aguas subterráneas utilizando CFC en un acuífero de rocas cristalinas: datos provenientes de un sitio al sur de Suecia. Se determinaron las concentraciones de clorofluorucarbonos (CFC-11, CFC-12, y CFC-113) y de tritio en aguas subterráneas alojadas en rocas cristalinas fracturadas de Finnsjön, Suecia. El objetivo específico consistió en investigar la precisión de la datación de aguas subterráneas con CFC en este tipo de ambiente, tomando en consideración la degradación potencial y la mezcla de agua. Las muestras de agua se tomaron a una profundidad de 42 m en tres pozos ubicados a lo largo de una línea de 800 m transversal a una zona de recarga y de zona de descarga local. En la mayoría de las muestras se encontró que la concentración de CFC-113 estuvo en el límite de detección. La edad que se estimó en todas las muestras para la recarga aparente en base a CFC-11 fue más joven que la edad proveniente de CFC-12, con una diferencia de más de 20 años para algunas muestras. Esta

  2. Constraining performance assessment models with tracer test results: a comparison between two conceptual models

    NASA Astrophysics Data System (ADS)

    McKenna, Sean A.; Selroos, Jan-Olof

    infini sur une période de temps spécifiée explique les différences entre les modèles et le ! fait que le test de traçage seul ne permet pas de déterminer les paramètres de transport à l'échelle du PA. Les résultats des simulations Monte Carlo du modèle de transport avec des temps et des distances de transport variables montrent des résultats concordances entre les différents modèles et suggère que la variation que la variation entre surface mouillée et le rapport de la différence de débits entre les lignes d'écoulement est insignifiante, en regard de la variabilité du montant de la capacité diffusive qui peut être accessible le long de la ligne de transport. Delimitando la eficacia de modelos de evaluación con resultados de pruebas de trazadores: una comparación entre dos modelos conceptuales. Se llevaron a cabo pruebas de trazadores para evaluar los parámetros de transporte de solutos en un rasgo rocoso a lo largo de una trayectoria de transporte de 5 m. Dos diferentes conceptualizaciones del transporte de solutos de porosidad doble aportan estimados de las curvas de avance de trazadores. Una de las conceptualizaciones (ritmo único) utiliza un coeficiente de difusión efectiva único en una matriz con profundidad de penetración infinita. Sin embargo, la retención del trazador entre diferentes trayectorias de flujo puede variar debido a que la relación entre la superficie mojada de flujo y el ritmo de flujo difiere entre las líneas de trayectoria. La otra conceptualización (multi-ritmo) utiliza una distribución continua de coeficientes de ritmos de difusión múltiple en una matriz con capacidad variable pero finita. La aplicación de los dos modelos con los parámetros estimados en base a las curvas de avance de trazadores producen resultados de transporte que difieren en varios órdenes de magnitud, tanto en concentración pico como en el tiempo en que se alcanza la concentración pico, en las escalas de evaluación de eficacia (PA) de