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Sample records for profundidad haliporoides diomedeae

  1. 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.

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

    PubMed

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

    2008-03-25

    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

  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. 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

  5. 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

  6. Serotonin immunoreactivity in the central nervous system of the marine molluscs Pleurobranchaea californica and Tritonia diomedea.

    PubMed

    Sudlow, L C; Jing, J; Moroz, L L; Gillette, R

    1998-06-15

    The central nervous systems of the marine molluscs Pleurobranchaea californica (Opisthobranchia: Notaspidea) and Tritonia diomedea (Opisthobranchia: Nudibranchia) were examined for serotonin-immunoreactive (5-HT-IR) neurons and processes. Bilaterally paired clusters of 5-HT-IR neuron somata were distributed similarly in ganglia of the two species. In the cerebropleural ganglion complex, these were the metacerebral giant neurons (both species), a dorsal anterior cluster (Pleurobranchaea only), a dorsal medial cluster including identified neurons of the escape swimming network (both species), and a dorsal lateral cluster in the cerebropleural ganglion (Pleurobranchaea only). A ventral anterior cluster (both species) adjoined the metacerebral giant somata at the anterior ganglion edge. Pedal ganglia had the greatest number of 5-HT-IR somata, the majority located near the roots of the pedal commissure in both species. Most 5-HT-IR neurons were on the dorsal surface of the pedal ganglia in Pleurobranchaea and were ventral in Tritonia. Neither the buccal ganglion of both species nor the visceral ganglion of Pleurobranchaea had 5-HT-IR somata. Afew asymmetrical 5-HT-IR somata were found in cerebropleural and pedal ganglia in both species, always on the left side. The clustering of 5-HT-IR neurons, their diverse axon pathways, and the known physiologic properties of their identified members are consistent with a loosely organized arousal system of serotonergic neurons whose components can be generally or differentially active in expression of diverse behaviors. PMID:9619500

  7. 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

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

    PubMed

    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

  9. 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

  10. 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

  11. 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.

  12. 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.

  13. 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. PMID:27126987

  14. 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.

  15. Chemical composition and tissue energy density of the cuttlefish (Sepia apama) and its assimilation efficiency by Diomedea albatrosses.

    PubMed

    Battam, H; Richardson, M; Watson, A W T; Buttemer, W A

    2010-11-01

    The cuttlefish Sepia apama Gray (Mollusca: Cephalopoda) is a seasonally abundant food resource exploited annually by moulting albatrosses throughout winter and early spring in the coastal waters of New South Wales, Australia. To assess its nutritional value as albatross forage, we analysed S. apama for water, lipid protein, ash contents, energy density and amino acid composition. Because albatrosses consistently consume S. apama parts preferentially in the order of head, viscera and mantle, we analysed these sections separately, but did not identify any nutritional basis for this selective feeding behaviour. The gross energy value of S. apama bodies was 20.9 kJ/g dry mass, but their high water content (>83%; cf <70% for fish) results in a relatively low energy density of 3.53 kJ/g. This may contribute to a need to take large meals, which subsequently degrade flight performance. Protein content was typically >75% dry mass, whereas fat content was only about 1%. Albatrosses feed on many species of cephalopods and teleost fish, and we found the amino acid composition of S. apama to be comparable to a range of species within these taxa. We used S. apama exclusively in feeding trials to estimate the energy assimilation efficiency for Diomedea albatrosses. We estimated their nitrogen-corrected apparent energy assimilation efficiency for consuming this prey to be 81.82 ± 0.72% and nitrogen retention as 2.90 ± 0.11 g N kg(-1) d(-1). Although S. apama has a high water content and relatively low energy density, its protein composition is otherwise comparable to other albatross prey species. Consequently, the large size and seasonal abundance of this prey should ensure that albatrosses remain replete and adequately nourished on this forage while undergoing moult. PMID:20640855

  16. 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

  17. 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

  18. Trace element accumulation in short-tailed albatrosses (Diomedea albatrus) and black-footed albatrosses (Diomedea nigripes) from Torishima Island, Japan

    NASA Astrophysics Data System (ADS)

    Shinsuke, T.; Tokutaka, I.; Takashi, K.; Miyako, T.; Fumio, S.; Nariko, O.

    2003-05-01

    Concentrations of 19 trace elements (V, Cr, Mn, Co, Cu, Zn, Ga, Se, Rb, Sr, Mo, Ag, Cd, Sb, Cs, Ba, Hg, Tl, and Pb) were determined in liver, kidney, muscle, feather and stomach content of short-tailed albatross and feather of black-footed albatross from Torishima Island, Japan. For most of the elements, concentrations in liver and kidney were higher than those in muscle and feather, whereas concentrations of Ga, Sr and Ba were highest in feather of short-taled albatross. Metal concentrations in tissues of short-tailed albatross were within the range of those reported for albatrosses from other locations. Concentrations of Cr, Mn, Hg and Pb were relatively low in the tissues of short-tailed albatross, indicating less contamination by those metals in this species of Torishima Island. No significant differences were observed in metal concentrations in feather between short-tailed albatross and black-footed albatross. To our knowledge, this is the first report on the trace element accumulation in tissues of short-tailed albatross.

  19. Insight of scent: experimental evidence of olfactory capabilities in the wandering albatross (Diomedea exulans).

    PubMed

    Mardon, J; Nesterova, A P; Traugott, J; Saunders, S M; Bonadonna, F

    2010-02-15

    Wandering albatrosses routinely forage over thousands of kilometres of open ocean, but the sensory mechanisms used in the food search itself have not been completely elucidated. Recent telemetry studies show that some spatial behaviours of the species are consistent with the 'multimodal foraging strategy' hypothesis which proposes that birds use a combination of olfactory and visual cues while foraging at sea. The 'multimodal foraging strategy' hypothesis, however, still suffers from a lack of experimental evidence, particularly regarding the olfactory capabilities of wandering albatrosses. As an initial step to test the hypothesis, we carried out behavioural experiments exploring the sensory capabilities of adult wandering albatrosses at a breeding colony. Three two-choice tests were designed to investigate the birds' response to olfactory and visual stimuli, individually or in combination. Perception of the different stimuli was assessed by comparing the amount of exploration directed towards an 'experimental' display or a 'control' display. Our results indicate that birds were able to perceive the three types of stimulus presented: olfactory, visual and combined. Moreover, olfactory and visual cues were found to have additional effects on the exploratory behaviours of males. This simple experimental demonstration of reasonable olfactory capabilities in the wandering albatross supports the 'multimodal foraging strategy' and is consistent with recent hypotheses of the evolutionary history of procellariiforms. PMID:20118306

  20. Recoveries of banded Laysan albatrosses (Diomedea immutabilis) and black-footed albatrosses (D. nigripes)

    USGS Publications Warehouse

    Robbins, C.S.; Rice, D.W.

    1974-01-01

    Summarizes the seasonal distribution of pelagic recoveries of 324 banded Laysan Albatrosses and 399 banded Black-footed Albatrosses. Different age groups of each species concentrate in somewhat different areas, and, although range overlap between species is almost complete, each has its own distinctive seasonal distribution pattern.

  1. 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

  2. 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

  3. Influence of age, sex and breeding status on mercury accumulation patterns in the wandering albatross Diomedea exulans.

    PubMed

    Tavares, S; Xavier, J C; Phillips, R A; Pereira, M E; Pardal, M A

    2013-10-01

    Although mercury bio-amplifies through the food chain and accumulates in top predators, mercury concentrations in tissues of the wandering albatross are greater than in any other vertebrate, including closely related species. In order to explore the alternative explanations for this pattern, we measured total mercury concentrations in feathers, plasma and blood cells of wandering albatrosses of known age, sex and breeding status sampled at South Georgia. Mercury concentrations were low in feathers and blood components of chicks, and higher in the feathers of young pre-breeders than in feathers or blood of older pre-breeders and breeding adults. There was no effect of sex on mercury concentrations in the feathers of pre-breeders or breeding adults, whereas levels were significantly higher in blood cells of breeding females than males. The high feather mercury concentrations of young pre-breeders compared with older birds suggest an increase in moult frequency as birds approach maturity. PMID:23859845

  4. 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

  5. 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.

  6. Population dynamics of shrimps in littoral marine waters of the Mekong Delta, south of Viet Nam.

    PubMed

    Dinh, T D; Moreau, J; Van, M V; Phuong, N T; Toan, V T

    2010-07-15

    The population dynamics of eight commercial species of shrimp (Haliporoides sibogae, Harpiosquilla harpax, Metapenaeus affinis, Metapenaeus brevicornis, Metapenaeus tenuipes, Parapenaeopsis cultrirostris, Parapenaeopsis gracillima and Parapenaeus maxilipedo) distributed in littoral marine zone of the Mekong Delta were investigated. Length-based stock assessment using FiSAT II software package was used to assess the growth and mortality parameters: Asymptotic size (L8), growth coefficient (K), total (Z) and natural (M) mortality, exploitation rate (E), recruitment pattern, current probability of capture and selectivity of fishing gears. Yield-per-recruit analyses were carried out showing different levels of the exploitation. Results showed that the maximum sustainable yield would be reached for an exploitation rate higher than the current one for each population. However, the size of first capture should be increased for every population. The findings indicated that the current exploitations of shrimp populations distributed in littoral marine zone of the Mekong Delta are under exploitation level for maximum sustainable yield; however, all the shrimp populations are subject to growth over-exploitation. PMID:21848060

  7. Hydroxylated and methylsulfonyl polychlorinated biphenyl metabolites in albatrosses from Midway Atoll, North Pacific Ocean

    SciTech Connect

    Klasson-Wehler, E.; Bergman, A.; Athanasiadou, M.

    1998-08-01

    Concentrations of hydroxylated metabolites of polychlorinated biphenyls (PCBs) (OH-PCBs) and methylsulfonyl metabolites of PCBs (MeSO{sub 2}-PCBs) were determined in plasma and liver of albatrosses collected from the Midway Atoll in the central North Pacific Ocean. The mean total concentrations of OH-PCBs in plasma of Laysan albatrosses (Diomedea immutabilis) and black-footed albatrosses (Diomedea nigripes) were 11.5 and 27.1 ng/g wet weight, respectively. Total concentrations of OH-PCBs were only one- to fivefold less than those of total PCBs. 4-hydroxy-2,2{prime},3,4{prime},5,5{prime},6-heptachlorinated biphenyl and 4-hydroxy-2,2{prime},3,4{prime},5,5{prime}-hexachlorinated biphenyl were the predominant polychlorinated biphenylols, constituting 70 to 90% of the total OH-PCBs. Concentrations of MeSO{sub 2}-PCBs in liver were between 10.6 and 77 ng/g, lipid weight, approximately 250 times less than those of total PCBs. The MeSO{sub 2}-PCBs congeners retained in the liver were dominated by those having the methylsulfonyl group in the 3-position.

  8. Population Structure and Dispersal Patterns within and between Atlantic and Mediterranean Populations of a Large-Range Pelagic Seabird

    PubMed Central

    Genovart, Meritxell; Thibault, Jean-Claude; Igual, José Manuel; Bauzà-Ribot, Maria del Mar; Rabouam, Corinne; Bretagnolle, Vincent

    2013-01-01

    Dispersal is critically linked to the demographic and evolutionary trajectories of populations, but in most seabird species it may be difficult to estimate. Using molecular tools, we explored population structure and the spatial dispersal pattern of a highly pelagic but philopatric seabird, the Cory's shearwater Calonectris diomedea. Microsatellite fragments were analysed from samples collected across almost the entire breeding range of the species. To help disentangle the taxonomic status of the two subspecies described, the Atlantic form C. d. borealis and the Mediterranean form C. d. diomedea, we analysed genetic divergence between subspecies and quantified both historical and recent migration rates between the Mediterranean and Atlantic basins. We also searched for evidence of isolation by distance (IBD) and addressed spatial patterns of gene flow. We found a low genetic structure in the Mediterranean basin. Conversely, strong genetic differentiation appeared in the Atlantic basin. Even if the species was mostly philopatric (97%), results suggest recent dispersal between basins, especially from the Atlantic to the Mediterranean (aprox. 10% of migrants/generation across the last two generations). Long-term gene flow analyses also suggested an historical exchange between basins (about 70 breeders/generation). Spatial analysis of genetic variation indicates that distance is not the main factor in shaping genetic structure in this species. Given our results we recommend gathering more data before concluded whether these taxa should be treated as two species or subspecies. PMID:23950986

  9. 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.

  10. Age-related variation in reproductive traits in the wandering albatross: evidence for terminal improvement following senescence.

    PubMed

    Froy, Hannah; Phillips, Richard A; Wood, Andrew G; Nussey, Daniel H; Lewis, Sue

    2013-05-01

    The processes driving age-related variation in demographic rates are central to understanding population and evolutionary ecology. An increasing number of studies in wild vertebrates find evidence for improvements in reproductive performance traits in early adulthood, followed by senescent declines in later life. However, life history theory predicts that reproductive investment should increase with age as future survival prospects diminish, and that raised reproductive investment may have associated survival costs. These non-mutually exclusive processes both predict an increase in breeding performance at the terminal breeding attempt. Here, we use a 30-year study of wandering albatrosses (Diomedea exulans) to disentangle the processes underpinning age-related variation in reproduction. Whilst highlighting the importance of breeding experience, we reveal senescent declines in performance are followed by a striking increase in breeding success and a key parental investment trait at the final breeding attempt. PMID:23438213

  11. Chloroplasts as functional organelles in animal tissues.

    PubMed

    Trench, R K; Greene, R W; Bystrom, B G

    1969-08-01

    The marine gastropod molluscs Tridachia crispata, Tridachiella diomedea, and Placobranchus ianthobapsus (Sacoglossa, Opisthobranchia) possess free functional chloroplasts within the cells of the digestive diverticula, as determined by observations on ultrastructure, pigment analyses, and experiments on photosynthetic capacity. In the light, the chloroplasts incorporate H(14)CO(3) (-)in situ. Reduced radiocarbon is translocated to various chloroplast-free tissues in the animals. The slugs feed on siphonaceous algae from which the chloroplasts are derived. Pigments from the slugs and from known siphonaceous algae, when separated chromatographically and compared, showed similar components. Absorption spectra of extracts of slugs and algae were very similar. The larvae of the slugs are pigment-free up to the post-veliger stage, suggesting that chloroplasts are acquired de novo. with each new generation. PMID:5792329

  12. 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.

  13. Orientation in the wandering albatross: interfering with magnetic perception does not affect orientation performance.

    PubMed

    Bonadonna, F; Bajzak, C; Benhamou, S; Igloi, K; Jouventin, P; Lipp, H P; Dell'Omo, G

    2005-03-01

    After making foraging flights of several thousands of kilometers, wandering albatrosses (Diomedea exulans) are able to pinpoint a specific remote island where their nests are located. This impressive navigation ability is highly precise but its nature is mysterious. Here we examined whether albatrosses rely on the perception of the Earth's magnetic field to accomplish this task. We disturbed the perception of the magnetic field using mobile magnets glued to the head of nine albatrosses and compared their performances with those of 11 control birds. We then used satellite telemetry to monitor their behavior. We found that the ability of birds to home specific nest sites was unimpaired by this manipulation. In particular, experimental and control birds did not show significant differences with respect to either foraging trip duration, or length, or with respect to homing straightness index. Our data suggest that wandering albatrosses do not require magnetic cues to navigate back to their nesting birds. PMID:15799944

  14. 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.

  15. 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.

  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. PMID:26827096

  17. 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. PMID:24102157

  18. The effect of food temperature on postprandial metabolism in albatrosses.

    PubMed

    Battam, H; Chappell, M A; Buttemer, W A

    2008-04-01

    Heat generated by the specific dynamic action (SDA) associated with feeding is known to substitute for the thermoregulatory costs of cold-exposed endotherms; however, the effectiveness of this depends on food temperature. When food is cooler than core body temperature, it is warmed by body heat and, consequently, imposes a thermoregulatory challenge to the animal. The degree to which this cost might be ;paid' by SDA depends on the relative timing of food heating and the SDA response. We investigated this phenomenon in two genera of endotherms, Diomedea and Thalassarche albatrosses, by measuring postprandial metabolic rate following ingestion of food at body temperature (40 degrees C) and cooler (0 and 20 degrees C). This permitted us to estimate potential contributions to food warming by SDA-derived heat, and to observe the effect of cold food on metabolic rate. For meal sizes that were approximately 20% of body mass, SDA was 4.22+/-0.37% of assimilated food energy, and potentially contributed 17.9+/-1.0% and 13.2+/-2.2% of the required heating energy of food at 0 degrees C for Diomedea and Thalassarche albatrosses, respectively, and proportionately greater quantities at higher food temperatures. Cold food increased the rate at which postprandial metabolic rate increased to 3.2-4.5 times that associated with food ingested at body temperature. We also found that albatrosses generated heat in excess by more than 50% of the estimated thermostatic heating demand of cold food, a probable consequence of time delays in physiological responses to afferent signals. PMID:18344483

  19. 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

  20. 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

  1. Experimental verification of dynamic soaring in albatrosses.

    PubMed

    Sachs, G; Traugott, J; Nesterova, A P; Bonadonna, F

    2013-11-15

    Dynamic soaring is a small-scale flight manoeuvre which is the basis for the extreme flight performance of albatrosses and other large seabirds to travel huge distances in sustained non-flapping flight. As experimental data with sufficient resolution of these small-scale movements are not available, knowledge is lacking about dynamic soaring and the physical mechanism of the energy gain of the bird from the wind. With new in-house developments of GPS logging units for recording raw phase observations and of a dedicated mathematical method for postprocessing these measurements, it was possible to determine the small-scale flight manoeuvre with the required high precision. Experimental results from tracking 16 wandering albatrosses (Diomedea exulans) in the southern Indian Ocean show the characteristic pattern of dynamic soaring. This pattern consists of four flight phases comprising a windward climb, an upper curve, a leeward descent and a lower curve, which are continually repeated. It is shown that the primary energy gain from the shear wind is attained in the upper curve where the bird changes the flight direction from windward to leeward. As a result, the upper curve is the characteristic flight phase of dynamic soaring for achieving the energy gain necessary for sustained non-flapping flight. PMID:24172888

  2. 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

  3. 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

  4. Lévy flight search patterns of wandering albatrosses

    NASA Astrophysics Data System (ADS)

    Viswanathan, G. M.; Afanasyev, V.; Buldyrev, S. V.; Murphy, E. J.; Prince, P. A.; Stanley, H. E.

    1996-05-01

    LéVY flights are a special class of random walks whose step lengths are not constant but rather are chosen from a probability distribution with a power-law tail. Realizations of Lévy flights in physical phenomena are very diverse, examples including fluid dynamics, dynamical systems, and micelles1,2. This diversity raises the possibility that Lévy flights may be found in biological systems. A decade ago, it was proposed that Lévy flights may be observed in the behaviour of foraging ants3. Recently, it was argued that Drosophila might perform Lévy flights4, but the hypothesis that foraging animals in natural environments perform Lévy flights has not been tested. Here we study the foraging behaviour of the wandering albatross Diomedea exulans, and find a power-law distribution of flight-time intervals. We interpret our finding of temporal scale invariance in terms of a scale-invariant spatial distribution of food on the ocean surface. Finally, we examine the significance of our finding in relation to the basis of scale-invariant phenomena observed in biological systems.

  5. 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. PMID:24586254

  6. Serotonin-like immunoreactivity in the central and peripheral nervous systems of the interstitial acochlidean Asperspina sp. (Opisthobranchia).

    PubMed

    Hochberg, Rick

    2007-08-01

    Species of Acochlidea are common members of the marine interstitial environment and defined in part by their minuscule size and highly divergent morphology relative to other benthic opisthobranchs. Despite these differences, acochlideans such as species of Asperspina display many plesiomorphic characteristics, including an unfused condition of their neural ganglia. To gain insight into the distribution of specific neural subsets within acochlidean ganglia, a species of Asperspina was studied by using anti-serotonin immunohistochemistry and epifluorescence and confocal laser scanning microscopy. Results reveal similarities between Asperspina and larger opisthobranchs in the general distribution of serotonergic perikarya in the central nervous system. Specifically, the arrangement of perikarya into regional clusters within the cerebral and pedal ganglia and the absence of immunoreactive perikarya in the pleural ganglia are similar to the model species of Aplysia californica, Pleurobranchaea californica, and Tritonia diomedea. Moreover, serotonergic innervation of the rhinophores in all opisthobranchs, including Asperspina sp., originates from the cerebral ganglion instead of directly from the rhinophoral ganglion. Serotonergic innervation of the body wall, including the epithelium, muscles, and pedal sole, appears to arise exclusively from pedal and accessory ganglia. These observations indicate a general conservation of serotonin-like immunoreactivity in the central and peripheral nervous systems of acochlidean and other benthic opisthobranchs. PMID:17679719

  7. Parallel evolution of serotonergic neuromodulation underlies independent evolution of rhythmic motor behavior.

    PubMed

    Lillvis, Joshua L; Katz, Paul S

    2013-02-01

    Neuromodulation can dynamically alter neuronal and synaptic properties, thereby changing the behavioral output of a neural circuit. It is therefore conceivable that natural selection might act upon neuromodulation as a mechanism for sculpting the behavioral repertoire of a species. Here we report that the presence of neuromodulation is correlated with the production of a behavior that most likely evolved independently in two species: Tritonia diomedea and Pleurobranchaea californica (Mollusca, Gastropoda, Opisthobranchia, Nudipleura). Individuals of both species exhibit escape swimming behaviors consisting of repeated dorsal-ventral whole-body flexions. The central pattern generator (CPG) circuits underlying these behaviors contain homologous identified neurons: DSI and C2 in Tritonia and As and A1 in Pleurobranchaea. Homologs of these neurons also can be found in Hermissenda crassicornis where they are named CPT and C2, respectively. However, members of this species do not exhibit an analogous swimming behavior. In Tritonia and Pleurobranchaea, but not in Hermissenda, the serotonergic DSI homologs modulated the strength of synapses made by C2 homologs. Furthermore, the serotonin receptor antagonist methysergide blocked this neuromodulation and the swimming behavior. Additionally, in Pleurobranchaea, the robustness of swimming correlated with the extent of the synaptic modulation. Finally, injection of serotonin induced the swimming behavior in Tritonia and Pleurobranchaea, but not in Hermissenda. This suggests that the analogous swimming behaviors of Tritonia and Pleurobranchaea share a common dependence on serotonergic neuromodulation. Thus, neuromodulation may provide a mechanism that enables species to acquire analogous behaviors independently using homologous neural circuit components. PMID:23392697

  8. [Evolutionary regularities of somatic polyploidy expansion in salivary glands of gastropod mollusks. V. Subclasses Opisthobranchia and Pulmonata].

    PubMed

    Anisimov, A P; Ziumchenko, N E

    2012-01-01

    Salivary glands of 25 species of euthyneural gastropod mollusks (Opisthobranchia and Pulmonata) have been investigated by means of histochemical methods and DNA cytophotometry in nuclei of cells. The cells of three basic types are distinguished in glandular epithelim: granular cells (with glicoproteid granular inclusions), mucocytes-I (with sulfatic acid mucopolysaccharides) and mucocytes-II (with neutral and acid nonsulfatic polysaccharides and proteins) and so the epithelial ciliated cells and cells of the ducts. It was shown that glandular cells of salivary glands of all discovered mollusks' species are polyploid in different degree. The highest ploidy level estimated by means of DNA content in most of species is 64-128c. The giant polyploidy, attained to 4096c, is discovered in cells of salivary glands of Tritonia diomedea. The functional conditionality connected with features of feeding of different mollusk species and phylogenetic tendencies of expansion of somatic polyploidy in class Gastropoda are discussed. In comparison with allogenic, facultative and small polyploidy manifestation in Prosobranchia the obligatory polyploidization of high degree revealed in cells of salivary glands of Opisthobranchia and Pulmonata is consider to be the original cytological arogenesis. The probable causes of such differences are conneted with euthyneural type of organization of central nervous system and giant polyploidy of neurons in Opisthobranchia and Pulmonata mollusks. The causes, mechanisms and significance of such correlations are unclear for the present. PMID:22590930

  9. Evidence for homologous peptidergic neurons in the buccal ganglia of diverse nudibranch mollusks.

    PubMed

    Watson, W H; Willows, A O

    1992-03-01

    The buccal ganglia of seven nudibranches (Aeolidia papillosa, Armina californica, Dirona albolineata, D. picta, Hermissenda crassicornis, Melibe leonina, and Tritonia diomedea) were examined to explore possible homologies between large cells that reacted with antibodies directed against small cardioactive peptide B (SCPB). The buccal ganglion of each species possessed a pair of large, dorsal-lateral, whitish neurons that contained an SCPB-like peptide. We refer to these neurons as the SLB (SCPB-immunoreactive Large Buccal) cells. In all species examined, the SLB cells project out the gastroesophageal nerves and appear to innervate the esophagus. In each species, an apparent rhythmic feeding motor program (FMP) was observed by intracellular recording from both SLB neurons and other neurons in isolated preparations of the buccal ganglia. SLB cells often fire at a high frequency, and usually burst in a specific phase relation to the FMP activity. Stimulation of SLB cells enhances expression of the feeding motor program, either by potentiating existing activity or eliciting the FMP in quiescent preparations. Finally, perfusion of isolated buccal ganglia with SCPB excites the SLB cells and activates FMPs. Thus, both the immunohistochemical and electrophysiological data suggest that the SLB cells within three suborders of the opisthobranchia (Dendronotacea, Arminacea, and Aeolidacea) are homologous. A comparison of our data with previously published studies indicates that SLB cell homologs may exist in other gastropods as well. PMID:1527526

  10. 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

  11. Removal of spike frequency adaptation via neuromodulation intrinsic to the Tritonia escape swim central pattern generator.

    PubMed

    Katz, P S; Frost, W N

    1997-10-15

    For the mollusc Tritonia diomedea to generate its escape swim motor pattern, interneuron C2, a crucial member of the central pattern generator (CPG) for this rhythmic behavior, must fire repetitive bursts of action potentials. Yet, before swimming, repeated depolarizing current pulses injected into C2 at periods similar those in the swim motor program are incapable of mimicking the firing rate attained by C2 on each cycle of a swim motor program. This resting level of C2 inexcitability is attributable to its own inherent spike frequency adaptation (SFA). Clearly, this property must be altered for the swim behavior to occur. The pathway for initiation of the swimming behavior involves activation of the serotonergic dorsal swim interneurons (DSIs), which are also intrinsic members of the swim CPG. Physiologically appropriate DSI stimulation transiently decreases C2 SFA, allowing C2 to fire at higher rates even when repeatedly depolarized at short intervals. The increased C2 excitability caused by DSI stimulation is mimicked and occluded by serotonin application. Furthermore, the change in excitability is not caused by the depolarization associated with DSI stimulation or serotonin application but is correlated with a decrease in C2 spike afterhyperpolarization. This suggests that the DSIs use serotonin to evoke a neuromodulatory action on a conductance in C2 that regulates its firing rate. This modulatory action of one CPG neuron on another is likely to play a role in configuring the swim circuit into its rhythmic pattern-generating mode and maintaining it in that state. PMID:9315892

  12. Feather corticosterone of a nestling seabird reveals consequences of sex-specific parental investment

    PubMed Central

    Fairhurst, Graham D.; Navarro, Joan; González-Solís, Jacob; Marchant, Tracy A.; Bortolotti, Gary R.

    2012-01-01

    Offspring of long-lived species should face costs of parental trade-offs that vary with overall energetic demands encountered by parents during breeding. If sex differences exist in how parents make the trade-off, sex-specific differences may exist in the contribution of each parent to those costs. Adaptations of offspring facing such costs are not well understood, but the hormone corticosterone probably plays a role. We manipulated breeding effort in Cory's shearwaters (Calonectris diomedea) to increase costs to offspring and used an integrated measure of corticosterone from chick feathers to investigate how experimental variation in parental investment influences offspring physiology. Average foraging trip duration and foraging efficiency (FE) of breeding pairs were not related to chick corticosterone, but sex biases in FE were. Adult male investment was more strongly related to chick corticosterone than was female investment. Importantly, we show for the first time suppression of adrenocortical activity in nestling Procellariiform seabirds, and explain how our results indicate an adaptive mechanism invoked by chicks facing increased costs of parental trade-offs. PMID:21632628

  13. 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

  14. 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.

  15. 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

  16. 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.

  17. 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

  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. 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. 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

  1. 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

  2. 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

  3. 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

  4. Fast and fuel efficient? Optimal use of wind by flying albatrosses.

    PubMed

    Weimerskirch, H; Guionnet, T; Martin, J; Shaffer, S A; Costa, D P

    2000-09-22

    The influence of wind patterns on behaviour and effort of free-ranging male wandering albatrosses (Diomedea exulans) was studied with miniaturized external heart-rate recorders in conjunction with satellite transmitters and activity recorders. Heart rate was used as an instantaneous index of energy expenditure. When cruising with favourable tail or side winds, wandering albatrosses can achieve high flight speeds while expending little more energy than birds resting on land. In contrast, heart rate increases concomitantly with increasing head winds, and flight speeds decrease. Our results show that effort is greatest when albatrosses take off from or land on the water. On a larger scale, we show that in order for birds to have the highest probability of experiencing favourable winds, wandering albatrosses use predictable weather systems to engage in a stereotypical flight pattern of large looping tracks. When heading north, albatrosses fly in anticlockwise loops, and to the south, movements are in a clockwise direction. Thus, the capacity to integrate instantaneous eco-physiological measures with records of large-scale flight and wind patterns allows us to understand better the complex interplay between the evolution of morphological, physiological and behavioural adaptations of albatrosses in the windiest place on earth. PMID:11052538

  5. 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.

  6. 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

  7. Different means to the same end: long-distance migrant seabirds from two colonies differ in behaviour, despite common wintering grounds.

    PubMed

    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

  8. Phylogeography of the Calonectris shearwaters using molecular and morphometric data.

    PubMed

    Gómez-Díaz, E; González-Solís, J; Peinado, M A; Page, R D M

    2006-11-01

    We investigated phylogenetic relationships and the biogeographic history of the Calonectris species complex, using both molecular and biometric data from one population of the Cape Verde shearwater Calonectris edwardsii (Cape Verde Islands), one from the streaked shearwater C. leucomelas (western Pacific Ocean) and 26 from Cory's shearwater populations distributed across the Atlantic (C. d. borealis) and the Mediterranean (C. d. diomedea). The streaked shearwater appeared as the most basal and distant clades, whereas the genetic divergences among the three main clades within the Palearctic were similar. Clock calibrations match the first speciation event within Calonectris to the Panama Isthmus formation, suggesting a vicariant scenario for the divergence of the Pacific and the Palearctic clades. The separation between the Atlantic and Mediterranean clades would have occurred in allopatry by range contraction followed by local adaptation during the major biogeographic events of the Pleistocene. The endemic form from Cape Verde probably evolved as a result of ecological divergence from the Mediterranean subspecies. Finally, one Mediterranean population (Almeria) was unexpectedly grouped into the Atlantic subspecies clade, both by genetic and by morphometric analyses, pointing out the Almeria-Oran oceanographic front (AOOF) as the actual divide between the two Cory's shearwater subspecies. Our results highlight the importance of oceanographic boundaries as potentially effective barriers shaping population and species phylogeographical structure in pelagic seabirds. PMID:16814569

  9. Further study of Contracaecum pelagicum (Nematoda: Anisakidae) in Spheniscus magellanicus (Aves: Spheniscidae) from Argentinean coasts.

    PubMed

    Garbin, Lucas E; Navone, Graciela T; Diaz, Julia I; Cremonte, Florencia

    2007-02-01

    The anisakid species Contracaecum pelagicum Johnston and Mawson, 1942, is reported for first time at 2 different sites on the Argentine coast (Peninsula Valdés, 42 degrees 04'S, 63 degrees 38'W and Mar del Plata, 38 degrees 05'S, 57 degrees 38'W), parasitizing the Magellanic penguin, Spheniscus magellanicus Foster. Morphometric analysis and further studies of adult specimens of C. pelagicum were done using light and scanning electron microscopy. The presence of bifurcated interlabia differentiates the present species from most others in the genus, except (1) from Contracaecum travassosi, which possesses higher interlabia and longer spicules, and a blunt, more constrained tail; (2) from Contracaecum rudolphii, which has longer spicules, blunter spicule tips, postparacloacal papillae with oblique disposition, and a blunter constrained tail; (3) from Contracaecum eudyptulae, which has a blunter tail and longer spicules; and (4) from Contracaecum variegatum, which possesses smaller-diameter, hooklike extensions on auricle lips, and a less robust interlabium with a more marked furrow. In this paper we present the first detailed description of C. pelagicum adults from S. magellanicus. Morphometric data between adult specimens of C. pelagicum from S. magellanicus and those from the black-browed albatross, Diomedea melanophris Temminck, from Argentinean coasts were compared. In addition, fourth-stage larvae that parasitized both hosts were assigned to a nondeterminated Contracaecum species. Ecological parameters for adults and larvae nematodes were calculated. PMID:17436954

  10. Characterization of avian poxvirus in Anna's Hummingbird (Calypte anna) in California, USA.

    PubMed

    Godoy, Loreto A; Dalbeck, Lisa S; Tell, Lisa A; Woods, Leslie W; Colwell, Rita R; Robinson, Barbara; Wethington, Susan M; Moresco, Anneke; Woolcock, Peter R; Ernest, Holly B

    2013-10-01

    Avian poxvirus (genus Avipoxvirus, family Poxviridae) is an enveloped double-stranded DNA virus that may be transmitted to birds by arthropod vectors or mucosal membrane contact with infectious particles. We characterized the infection in Anna's Hummingbird (Calypte anna; n = 5 birds, n = 9 lesions) by conducting diagnostic tests on skin lesions that were visually similar to avian poxvirus lesions in other bird species. Skin lesions were single or multiple, dry and firm, pink to yellow, with scabs on the surface, and located at the base of the bill, wings, or legs. Microscopically, the lesions were characterized by epidermal hyperplasia and necrosis with ballooning degeneration, and intracytoplasmic inclusions (Bollinger bodies) in keratinocytes. The 4b core gene sequence of avian poxvirus was detected by PCR in samples prepared from lesions. Nucleotide sequences were 75-94% similar to the sequences of other published avian poxvirus sequences. Phylogenetic analyses showed that the Anna's Hummingbird poxvirus sequence was distinguished as a unique subclade showing similarities with sequences isolated from Ostrich (Struthio camelus), Wild Turkey (Meleagris gallopavo), falcons (Falco spp.), Black-browed Albatross (Diomedea melanophris), Mourning Dove (Zenaida macroura) and White-tailed Eagle (Haliaeetus albicilla). To our knowledge this is the first published report of definitive laboratory diagnosis of avian poxvirus in a hummingbird. Our results advance the science of disease ecology in hummingbirds, providing management information for banders, wildlife rehabilitators, and avian biologists. PMID:24502725

  11. 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

  12. 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

  13. 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

  14. 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

  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. The Effects of Spatially Heterogeneous Prey Distributions on Detection Patterns in Foraging Seabirds

    PubMed Central

    Miramontes, Octavio; Boyer, Denis; Bartumeus, Frederic

    2012-01-01

    Many attempts to relate animal foraging patterns to landscape heterogeneity are focused on the analysis of foragers movements. Resource detection patterns in space and time are not commonly studied, yet they are tightly coupled to landscape properties and add relevant information on foraging behavior. By exploring simple foraging models in unpredictable environments we show that the distribution of intervals between detected prey (detection statistics) is mostly determined by the spatial structure of the prey field and essentially distinct from predator displacement statistics. Detections are expected to be Poissonian in uniform random environments for markedly different foraging movements (e.g. Lévy and ballistic). This prediction is supported by data on the time intervals between diving events on short-range foraging seabirds such as the thick-billed murre (Uria lomvia). However, Poissonian detection statistics is not observed in long-range seabirds such as the wandering albatross (Diomedea exulans) due to the fractal nature of the prey field, covering a wide range of spatial scales. For this scenario, models of fractal prey fields induce non-Poissonian patterns of detection in good agreement with two albatross data sets. We find that the specific shape of the distribution of time intervals between prey detection is mainly driven by meso and submeso-scale landscape structures and depends little on the forager strategy or behavioral responses. PMID:22514629

  17. 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. PMID:25574995

  18. 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

  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. Females better face senescence in the wandering albatross.

    PubMed

    Pardo, Deborah; Barbraud, Christophe; Weimerskirch, Henri

    2013-12-01

    Sex differences in lifespan and aging are widespread among animals. Since investment in current reproduction can have consequences on other life-history traits, the sex with the highest cost of breeding is expected to suffer from an earlier and/or stronger senescence. This has been demonstrated in polygynous species that are highly dimorphic. However in monogamous species where parental investment is similar between sexes, sex-specific differences in aging patterns of life-history traits are expected to be attenuated. Here, we examined sex and age influences on demographic traits in a very long-lived and sexually dimorphic monogamous species, the wandering albatross (Diomedea exulans). We modelled within the same model framework sex-dependent variations in aging for an array of five life-history traits: adult survival, probability of returning to the breeding colony, probability of breeding and two measures of breeding success (hatching and fledging). We show that life-history traits presented contrasted aging patterns according to sex whereas traits were all similar at young ages. Both sexes exhibited actuarial and reproductive senescence, but, as the decrease in breeding success remained similar for males and females, the survival and breeding probabilities of males were significantly more affected than females. We discuss our results in the light of the costs associated to reproduction, age-related pairing and a biased operational sex-ratio in the population leading to a pool of non-breeders of potentially lower quality and therefore more subject to death or breeding abstention. For a monogamous species with similar parental roles, the patterns observed were surprising and when placed in a gradient of observed age/sex-related variations in life-history traits, wandering albatrosses were intermediate between highly dimorphic polygynous and most monogamous species. PMID:23797411

  1. Do naive juvenile seabirds forage differently from adults?

    PubMed

    Riotte-Lambert, Louise; Weimerskirch, Henri

    2013-10-01

    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

  2. The seabird paradox: dispersal, genetic structure and population dynamics in a highly mobile, but philopatric albatross species.

    PubMed

    Milot, Emmanuel; Weimerskirch, Henri; Bernatchez, Louis

    2008-04-01

    The philopatric behaviour of albatrosses has intrigued biologists due to the high mobility of these seabirds. It is unknown how albatrosses maintain a system of fragmented populations without frequent dispersal movements, in spite of the long-term temporal heterogeneity in resource distribution at sea. We used both genetic (amplified fragment length polymorphism) and capture-mark-recapture (CMR) data to identify explicitly which among several models of population dynamics best applies to the wandering albatross (Diomedea exulans) and to test for migration-drift equilibrium. We previously documented an extremely low genetic diversity in this species. Here, we show that populations exhibit little genetic differentiation across the species' range (Theta(B) < 0.05, where Theta(B) is an F(ST) analogue). Furthermore, there was no evidence of hierarchical structure or isolation-by-distance. Wright's F(ST) between pairs of colonies were low in general and the pattern was consistent with a nonequilibrium genetic model. In contrast, CMR data collected over the last decades indicated that about one bird per cohort has dispersed among islands. Overall, F(ST) values were not indicative of contemporary dispersal as inferred from CMR data. Moreover, all genotypes grouped together in a cluster analysis, indicating that current colonies may have derived from one ancestral source that had a low genetic diversity. A metapopulation dynamics model including a recent (postglacial) colonization of several islands seems consistent with both the very low levels of genetic diversity and structure within the wandering albatross. Yet, our data suggest that several other factors including ongoing gene flow, recurrent long-distance dispersal and source-sink dynamics have contributed to different extent in shaping the genetic signature observed in this species. Our results show that an absence of genetic structuring may in itself reveal little about the true population dynamics in seabirds, but

  3. Age, sex, and breeding status shape a complex foraging pattern in an extremely long-lived seabird.

    PubMed

    Jaeger, Audrey; Goutte, Aurélie; Lecomte, Vincent J; Richard, Pierre; Chastel, Olivier; Barbraud, Christophe; Weimerskirch, Henri

    2014-08-01

    Evidence of age-dependent changes in foraging behavior of free-ranging individuals is scarce, especially at older stages. Using the isotopic niche as a proxy of the trophic niche during both the breeding (blood) and inter-nesting (feather) periods, we report here empirical evidence for age-, gender-, and breeding status-dependent foraging ecology and examine its potential consequences on subsequent reproduction and survival in an extremely long-lived species, the Wandering Albatross (Diomedea exulans). Immature Wandering Albatrosses of both sexes forage in the subtropics (delta13C) and feed at the same trophic position (delta15N) as the adults. In contrast to immature birds, adult females forage, on average, at more northern latitudes than males, with both sexes feeding in the subtropics during the internesting period, and males, not females, favoring subantarctic waters during incubation. In contrast to adult females, males show a unique pattern among birds and mammals of a continuous change with age in their main feeding habitat by foraging progressively farther south in colder waters during both the breeding and inter-nesting periods. In males, foraging at higher latitudes (lower feather delta13C values) is associated with a lower probability of breeding during the following years compared to other birds, but with no effect on their probability of surviving. Foraging in cold and windy waters may be linked to foraging impairment that might explain different life history trade-offs and lower investment in reproduction with age. This key point requires further longitudinal investigations and/or studies examining foraging success and the energy budget of birds feeding in different water masses. PMID:25230482

  4. 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

  5. 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

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

    PubMed

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

    2012-06-26

    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

  7. 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.

  8. 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

  9. 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

  10. Spike timing-dependent serotonergic neuromodulation of synaptic strength intrinsic to a central pattern generator circuit.

    PubMed

    Sakurai, Akira; Katz, Paul S

    2003-11-26

    Neuromodulation is often thought to have a static, gain-setting function in neural circuits. Here we report a counter example: the neuromodulatory effect of a serotonergic neuron is dependent on the interval between its spikes and those of the neuron being modulated. The serotonergic dorsal swim interneurons (DSIs) are members of the escape swim central pattern generator (CPG) in the mollusk Tritonia diomedea. DSI spike trains heterosynaptically enhanced synaptic potentials evoked by another CPG neuron, ventral swim interneuron B (VSI-B), when VSI-B action potentials occurred within 10 sec of a DSI spike train; however, if VSI-B was stimulated 20-120 sec after DSI, then the amplitude of VSI-B synaptic potentials decreased. Consistent with this, VSI-B-evoked synaptic currents exhibited a temporally biphasic and bidirectional change in amplitude after DSI stimulation. Both the DSI-evoked enhancement and decrement were occluded by serotonin and blocked by the serotonin receptor antagonist methysergide, suggesting that both phases are mediated by serotonin. In most preparations, however, bath-applied serotonin caused only a sustained enhancement of VSI-B synaptic strength. The heterosynaptic modulation interacted with short-term homosynaptic plasticity: DSI-evoked depression was offset by VSI-B homosynaptic facilitation. This caused a complicated temporal pattern of neuromodulation when DSI and VSI-B were stimulated to fire in alternating bursts to mimic the natural motor pattern: DSI strongly enhanced summated VSI-B synaptic potentials and suppressed single synaptic potentials after the cessation of the artificial motor pattern. Thus, spike timing-dependent serotonergic neuromodulatory actions can impart temporal information that may be relevant to the operation of the CPG. PMID:14645466

  11. 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

  12. 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

  13. 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.

  14. 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

  15. 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

  16. 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

  17. Variable Neuronal Participation in Stereotypic Motor Programs

    PubMed Central

    Hill, Evan S.; Vasireddi, Sunil K.; Bruno, Angela M.; Wang, Jean; Frost, William N.

    2012-01-01

    To what extent are motor networks underlying rhythmic behaviors rigidly hard-wired versus fluid and dynamic entities? Do the members of motor networks change from moment-to-moment or from motor program episode-to-episode? These are questions that can only be addressed in systems where it is possible to monitor the spiking activity of networks of neurons during the production of motor programs. We used large-scale voltage-sensitive dye (VSD) imaging followed by Independent Component Analysis spike-sorting to examine the extent to which the neuronal network underlying the escape swim behavior of Tritonia diomedea is hard-wired versus fluid from a moment-to-moment perspective. We found that while most neurons were dedicated to the swim network, a small but significant proportion of neurons participated in a surprisingly variable manner. These neurons joined the swim motor program late, left early, burst only on some cycles or skipped cycles of the motor program. We confirmed that this variable neuronal participation was not due to effects of the VSD by finding such neurons with intracellular recording in dye-free saline. Further, these neurons markedly varied their level of participation in the network from swim episode-to-episode. The generality of such unreliably bursting neurons was confirmed by their presence in the rhythmic escape networks of two other molluscan species, Tritonia festiva and Aplysia californica. Our observations support a view that neuronal networks, even those underlying rhythmic and stereotyped motor programs, may be more variable in structure than widely appreciated. PMID:22815768

  18. Ocean Surface Winds Drive Dynamics of Transoceanic Aerial Movements

    PubMed Central

    Felicísimo, Ángel 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. 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

  20. Combined spatio-temporal impacts of climate and longline fisheries on the survival of a trans-equatorial marine migrant.

    PubMed

    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

  1. 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

  2. Flight Modes in Migrating European Bee-Eaters: Heart Rate May Indicate Low Metabolic Rate during Soaring and Gliding

    PubMed Central

    Sapir, Nir; Wikelski, Martin; McCue, Marshall D.; Pinshow, Berry; Nathan, Ran

    2010-01-01

    Background Many avian species soar and glide over land. Evidence from large birds (mb>0.9 kg) suggests that soaring-gliding is considerably cheaper in terms of energy than flapping flight, and costs about two to three times the basal metabolic rate (BMR). Yet, soaring-gliding is considered unfavorable for small birds because migration speed in small birds during soaring-gliding is believed to be lower than that of flapping flight. Nevertheless, several small bird species routinely soar and glide. Methodology/Principal Findings To estimate the energetic cost of soaring-gliding flight in small birds, we measured heart beat frequencies of free-ranging migrating European bee-eaters (Merops apiaster, mb∼55 g) using radio telemetry, and established the relationship between heart beat frequency and metabolic rate (by indirect calorimetry) in the laboratory. Heart beat frequency during sustained soaring-gliding was 2.2 to 2.5 times lower than during flapping flight, but similar to, and not significantly different from, that measured in resting birds. We estimated that soaring-gliding metabolic rate of European bee-eaters is about twice their basal metabolic rate (BMR), which is similar to the value estimated in the black-browed albatross Thalassarche (previously Diomedea) melanophrys, mb∼4 kg). We found that soaring-gliding migration speed is not significantly different from flapping migration speed. Conclusions/Significance We found no evidence that soaring-gliding speed is slower than flapping flight in bee-eaters, contradicting earlier estimates that implied a migration speed penalty for using soaring-gliding rather than flapping flight. Moreover, we suggest that small birds soar and glide during migration, breeding, dispersal, and other stages in their annual cycle because it may entail a low energy cost of transport. We propose that the energy cost of soaring-gliding may be proportional to BMR regardless of bird size, as theoretically deduced by earlier studies

  3. 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

  4. 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

  5. The use of microsomal in vitro assay to study phase I biotransformation of chlorobornanes (Toxaphene) in marine mammals and birds. Possible consequences of biotransformation for bioaccumulation and genotoxicity.

    PubMed

    Boon, J P; Sleiderink, H M; Helle, M S; Dekker, M; van Schanke, A; Roex, E; Hillebrand, M T; Klamer, H J; Govers, B; Pastor, D; Morse, D; Wester, P G; de Boer, J

    1998-11-01

    The factors determining the bioaccumulation of lipophilic compounds in wildlife are often poorly understood, partly because it is difficult to do in vivo experiments with animals such as marine mammals and birds. To evaluate the role of phase I biotransformation in the bioaccumulation process of chlorobornanes (toxaphene), this was studied in in vitro assays with hepatic microsomes of animals that could be sampled shortly after death. The capacity of microsomes to metabolise a technical toxaphene mixture decreased in the order Phoca vitulina (harbour seal) > Lagenorhynchus albirostris (whitebeaked dolphin) approximately equal to Diomedea immutabilis (Laysan albatross) > Physeter macrocephalus (sperm whale). Harbour seal microsomes metabolised the chlorobornane (CHB) congeners CHB-32 and CHB-62; whitebeaked dolphin and Laysan albatross microsomes only metabolised CHB-32. Metabolism of CHB-26 and CHB-50 was never observed. The negative chemical ionisation (NCI-) mass spectra of some of the hydroxylated metabolites were obtained. The number of peaks in the toxaphene residues of wildlife extracts decreased in the order of increasing in-vitro biotransformation capacity. Thus, the results of the in vitro assays and residue analysis were in accordance, although assays with microsomes of more individuals of the same species are required for a more general conclusion at the species level. Finally, the effect of in vitro biotransformation was evaluated in terms of the genotoxic potential using the Mutatox assay. Only technical toxaphene and CHB-32 were genotoxic in the direct assay, whereas the addition of rat S9 fraction or microsomes of harbour seal and albatross decreased the genotoxic response. Thus, organisms with a low ability to metabolise chlorobornanes, such as whales, may be most affected by the carcinogenic properties of toxaphene. A hypothetical reaction which fits the experimental results is discussed. Based on these results it is concluded that in vitro assays

  6. 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.

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

    PubMed Central

    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

  8. 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

  9. 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

  10. 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

  11. 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

  12. 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.

  13. Observações no infravermelho médio de objetos estelares jovens em NGC 3576

    NASA Astrophysics Data System (ADS)

    Barbosa, C.; Damineli, A.; Blum, R.; Conti, P.

    2003-08-01

    Apresentamos os resultados de observações no infravermelho médio de candidatos a objetos estelares jovens e massivos em NGC 3576. As imagens de alta resolução foram obtidas no observatório Gemini Sul com o uso dos filtros em 10,8, 7,9, 9,8, 12,5 e 18,2 mm. Nossas imagens mostram a fonte IRS 1 resolvida em 4 objetos pela primeira vez em 10 mm. Para cada objeto obtivemos a distribuição espectral de energia de 1.2 até 18 mm, bem como a temperatura de cor, a distribuição espacial e a profundidade óptica em 9,8 mm da poeira circunstelar. Apresentamos uma estimativa das massas dos objetos estudados, baseados na luminosidade emitida no infravermelho médio, bem como um modelo para explicar as diferentes características observadas de cada objeto. Finalmente discutimos a possível localização da(s) fonte(s) de ionização de NGC 3576.

  14. 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

  15. 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).

  16. 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

  17. 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

  18. 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

  19. 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

  20. 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

  1. 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

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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.

  7. 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

  8. 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

  9. 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

  10. 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.

  11. 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

  12. 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.

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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

  18. 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

  19. 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

  20. 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

  1. 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

  2. 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

  3. 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.

  4. 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.

  5. 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

  6. 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

  7. 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

  8. 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

  9. 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

  10. 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