Science.gov

Sample records for prey protection measures

  1. Significance of Selective Predation and Development of Prey Protection Measures for Juvenile Salmonids in the Columbia and Snake River Reservoirs: Annual Progress Report, February 1991-February 1992.

    SciTech Connect

    Poe, Thomas P.

    1992-12-31

    This document is the 1991 annual report of progress for the Bonneville Power Administration (BPA) research Project conducted by the US Fish and Wildlife Service (FWS). Our approach was to present the progress achieved during 1991 in a series of separate reports for each major project task. Each report is prepared in the format of a scientific paper and is able to stand alone, whatever the state of progress or completion. This project has two major goals. One is to understand the significance of selective predation and prey vulnerability by determining if substandard juvenile salmonids (dead, injured, stressed, diseased, or naive) are more vulnerable to predation by northern squawfish, than standard or normal juvenile salmonids. The second goal is to develop and test prey protection measures to control predation on juvenile salmonids by reducing predator-smolt encounters or predator capture efficiency.

  2. Significance of Selective Predation and Development of Prey Protection Measures for Juvenile Salmonids in the Columbia and Snake River Reservoirs: Annual Progress Report, February 1993-February 1994.

    SciTech Connect

    Poe, Thomas P.

    1994-08-01

    This report addresses the problem of predator-prey interactions of juvenile salmonids in the Columbia and Snake River. Six papers are included on selective predation and prey protection. Attention is focused on monitoring the movements, the distribution, and the behavior of juvenile chinook salmon and northern squawfish.

  3. Significance of Selective Predation and Development of Prey Protection Measures for Juvenile Salmonids in the Columbia and Snake River Reservoirs: Annual Report, February 1992-February 1993.

    SciTech Connect

    Poe, Thomas P.; Gadomski, Dena M.

    1994-09-01

    This document is the 1992 annual report of progress for the Bonneville Power Administration (BPA) research Project No. 82-003 conducted by the U.S. Fish and Wildlife Service (FWS), the Oregon Cooperative Fishery Research Unit (OCFRU), and the Idaho Cooperative Fish and Wildlife Research Unit (ICFWRU). The approach was to present the progress achieved during 1992 in a series of separate reports for each major project task. Each report is prepared in the format of a scientific paper and is able to stand alone, whatever the state of progress or completion. Reports 1, 2, and 4 consist of the Abstract only (journal papers were submitted in lieu of reports). This project has two major goals. One is to understand the significance of selective predation and prey vulnerability by determining if substandard juvenile salmonids (dead, injured, stressed, diseased, or naive) are more vulnerable to predation by northern squawfish, Ptychocheilus oregonensis, than standard or normal juvenile salmonids. The second goal is to develop and test prey protection measures to control predation on juvenile salmonids by reducing predator-smolt encounters or predator capture efficiency. Separate abstracts have been submitted to the database for the seven articles in this report.

  4. Colour Polymorphism Protects Prey Individuals and Populations Against Predation

    PubMed Central

    Karpestam, Einat; Merilaita, Sami; Forsman, Anders

    2016-01-01

    Colour pattern polymorphism in animals can influence and be influenced by interactions between predators and prey. However, few studies have examined whether polymorphism is adaptive, and there is no evidence that the co-occurrence of two or more natural prey colour variants can increase survival of populations. Here we show that visual predators that exploit polymorphic prey suffer from reduced performance, and further provide rare evidence in support of the hypothesis that prey colour polymorphism may afford protection against predators for both individuals and populations. This protective effect provides a probable explanation for the longstanding, evolutionary puzzle of the existence of colour polymorphisms. We also propose that this protective effect can provide an adaptive explanation for search image formation in predators rather than search image formation explaining polymorphism. PMID:26902799

  5. The effectiveness of marine protected areas for predator and prey with varying mobility.

    PubMed

    Pilyugin, Sergei S; Medlock, Jan; De Leenheer, Patrick

    2016-08-01

    Marine protected areas (MPAs) are regions in the ocean where fishing is restricted or prohibited. Although several measures for MPA performance exist, here we focus on a specific one, namely the ratio of the steady state fish densities inside and outside the MPA. Several 2 patch models are proposed and analyzed mathematically. One patch represents the MPA, whereas the second patch represents the fishing ground. Fish move freely between both regions in a diffusive manner. Our main objective is to understand how fish mobility affects MPA performance. We show that MPA effectiveness decreases with fish mobility for single species models with logistic growth, and that densities inside and outside the MPA tend to equalize. This suggests that MPA performance is highest for the least mobile species. We then consider a 2 patch Lotka-Volterra predator-prey system. When one of the species moves, and the other does not, the ratio of the moving species first remains constant, and ultimately decreases with increased fish mobility, again with a tendency of equalization of the density in both regions. This suggests that MPA performance is not only highest for slow, but also for moderately mobile species. The discrepancy in MPA performance for single species models and for predator-prey models, confirms that MPA design requires an integrated, ecosystem-based approach. The mathematical approaches advocated here complement and enhance the numerical and theoretical approaches that are commonly applied to more complex models in the context of MPA design.

  6. The effectiveness of marine protected areas for predator and prey with varying mobility.

    PubMed

    Pilyugin, Sergei S; Medlock, Jan; De Leenheer, Patrick

    2016-08-01

    Marine protected areas (MPAs) are regions in the ocean where fishing is restricted or prohibited. Although several measures for MPA performance exist, here we focus on a specific one, namely the ratio of the steady state fish densities inside and outside the MPA. Several 2 patch models are proposed and analyzed mathematically. One patch represents the MPA, whereas the second patch represents the fishing ground. Fish move freely between both regions in a diffusive manner. Our main objective is to understand how fish mobility affects MPA performance. We show that MPA effectiveness decreases with fish mobility for single species models with logistic growth, and that densities inside and outside the MPA tend to equalize. This suggests that MPA performance is highest for the least mobile species. We then consider a 2 patch Lotka-Volterra predator-prey system. When one of the species moves, and the other does not, the ratio of the moving species first remains constant, and ultimately decreases with increased fish mobility, again with a tendency of equalization of the density in both regions. This suggests that MPA performance is not only highest for slow, but also for moderately mobile species. The discrepancy in MPA performance for single species models and for predator-prey models, confirms that MPA design requires an integrated, ecosystem-based approach. The mathematical approaches advocated here complement and enhance the numerical and theoretical approaches that are commonly applied to more complex models in the context of MPA design. PMID:27151107

  7. Attracting predators without falling prey: chemical camouflage protects honeydew-producing treehoppers from ant predation.

    PubMed

    Silveira, Henrique C P; Oliveira, Paulo S; Trigo, José R

    2010-02-01

    Predaceous ants are dominant organisms on foliage and represent a constant threat to herbivorous insects. The honeydew of sap-feeding hemipterans has been suggested to appease aggressive ants, which then begin tending activities. Here, we manipulated the cuticular chemical profiles of freeze-dried insect prey to show that chemical background matching with the host plant protects Guayaquila xiphias treehoppers against predaceous Camponotus crassus ants, regardless of honeydew supply. Ant predation is increased when treehoppers are transferred to a nonhost plant with which they have low chemical similarity. Palatable moth larvae manipulated to match the chemical background of Guayaquila's host plant attracted lower numbers of predatory ants than unchanged controls. Although aggressive tending ants can protect honeydew-producing hemipterans from natural enemies, they may prey on the trophobionts under shortage of alternative food resources. Thus chemical camouflage in G. xiphias allows the trophobiont to attract predaceous bodyguards at reduced risk of falling prey itself.

  8. The economics of protecting tiger populations: Linking household behavior to poaching and prey depletion

    USGS Publications Warehouse

    Damania, R.; Stringer, R.; Karanth, K.U.; Stith, B.

    2003-01-01

    The tiger (Panthera tigris) is classified as endangered and populations continue to decline. This paper presents a formal economic analysis of the two most imminent threats to the survival of wild tigers: poaching tigers and hunting their prey. A model is developed to examine interactions between tigers and farm households living in and around tiger habitats. The analysis extends the existing literature on tiger demography, incorporating predator-prey interactions and exploring the sensitivity of tiger populations to key economic parameters. The analysis aims to contribute to policy debates on how best to protect one of the world's most endangered wild cats.

  9. Breaking and entering: predators invade the shelter of their prey and gain protection.

    PubMed

    Lemos, Felipe; Bernardo, Ana Maria Guimarães; Dias, Cleide Rosa; Sarmento, Renato Almeida; Pallini, Angelo; Venzon, Madelaine; Janssen, Arne

    2015-10-01

    Many herbivorous arthropods construct shelters on their host plant that offer protection against natural enemies. This has resulted in selection on natural enemies to enter these shelters, where they can feed on prey that are inaccessible for competing predators and parasitoids. The spider mite Tetranychus evansi produces a shelter consisting of a dense web that is impenetrable for most predators; the only known natural enemy that can penetrate the web and can forage efficiently on this pest is Phytoseiulus longipes. We show that this predator preferentially foraged and oviposited in the web of its prey. Moreover, intraguild predation on juveniles of these predators was significantly higher outside this web and in the less dense web of a closely related prey species (T. urticae) than inside the web of T. evansi. Although the production of shelters by herbivores may be profitable at first, their adapted natural enemies may reap the benefit in the end. PMID:26188859

  10. Soil bioretention protects juvenile salmon and their prey from the toxic impacts of urban stormwater runoff.

    PubMed

    McIntyre, J K; Davis, J W; Hinman, C; Macneale, K H; Anulacion, B F; Scholz, N L; Stark, J D

    2015-08-01

    Green stormwater infrastructure (GSI), or low impact development, encompasses a diverse and expanding portfolio of strategies to reduce the impacts of stormwater runoff on natural systems. Benchmarks for GSI success are usually framed in terms of hydrology and water chemistry, with reduced flow and loadings of toxic chemical contaminants as primary metrics. Despite the central goal of protecting aquatic species abundance and diversity, the effectiveness of GSI treatments in maintaining diverse assemblages of sensitive aquatic taxa has not been widely evaluated. In the present study we characterized the baseline toxicity of untreated urban runoff from a highway in Seattle, WA, across six storm events. For all storms, first flush runoff was toxic to the daphniid Ceriodaphnia dubia, causing up to 100% mortality or impairing reproduction among survivors. We then evaluated whether soil media used in bioretention, a conventional GSI method, could reduce or eliminate toxicity to juvenile coho salmon (Oncorhynchus kisutch) as well as their macroinvertebrate prey, including cultured C. dubia and wild-collected mayfly nymphs (Baetis spp.). Untreated highway runoff was generally lethal to salmon and invertebrates, and this acute mortality was eliminated when the runoff was filtered through soil media in bioretention columns. Soil treatment also protected against sublethal reproductive toxicity in C. dubia. Thus, a relatively inexpensive GSI technology can be highly effective at reversing the acutely lethal and sublethal effects of urban runoff on multiple aquatic species.

  11. Predator-prey spatial game as a tool to understand the effects of protected areas on harvester-wildlife interactions.

    PubMed

    Tolon, Vincent; Martin, Jodie; Dray, Stéphane; Loison, Anne; Fischer, Claude; Baubet, Eric

    2012-03-01

    No-take reserves are sometimes implemented for sustainable population harvesting because they offer opportunities for animals to spatially avoid harvesters, whereas harvesters can benefit in return from the reserve spillover. Here, we used the framework of predator-prey spatial games to understand how protected areas shape spatial interactions between harvesters and target species and determine animal mortality. In these spatial games, the "predator" searches for "prey" and matches their habitat use, unless it meets spatial constraints offering the opportunity for prey to avoid the mortality source. However, such prey refuges could attract predators in the surroundings, which questions the potential benefits for prey. We located, in the Geneva Basin (France), hunting dogs and wild boar Sus scrofa L. during hunting seasons with global positioning systems and very-high-frequency collars. We quantified how the proximity of the reserve shaped the matching between both habitat uses using multivariate analyses and linked these patterns to animals' mortality with a Cox regression analysis. Results showed that habitat uses by both protagonists disassociated only when hunters were spatially constrained by the reserve. In response, hunters increased hunting efforts near the reserve boundary, which induced a higher risk exposure for animals settled over the reserve. The mortality of adult wild boar decreased near the reserve as the mismatch between both habitat uses increased. However the opposite pattern was determined for younger individuals that suffered from the high level of hunting close to the reserve. The predator-prey analogy was an accurate prediction of how the protected area modified spatial relationships between harvesters and target species. Prey-searching strategies adopted by hunters around reserves strongly impacted animal mortality and the efficiency of the protected area for this harvested species. Increasing reserve sizes and/or implementing buffer areas

  12. Do wildlife laws work? Species protection and the application of a prey choice model to poaching decisions.

    PubMed Central

    Rowcliffe, J. Marcus; de Merode, Emmanuel; Cowlishaw, Guy

    2004-01-01

    Legislation for the protection of species is a global conservation tool. However, in many developing countries lack of resources means that effectiveness relies on voluntary compliance, leading to contradictory assumptions. On one hand, laws introduced without effective enforcement mechanisms carry an implicit assumption that voluntary compliance will occur. On the other hand, it is often openly assumed that, without enforcement, there will in fact be no compliance. Which assumption holds has rarely been rigorously tested. Here we show that laws for the protection of some species of large mammal have no effect on the prey choice patterns of primarily commercial hunters in the Democratic Republic of Congo, confirming the second assumption. We established this result by using an optimal diet model to predict the pattern of prey choice in the absence of regulation. Prey choice patterns predicted by the model were accurate across a range of conditions defined by time, space and type of hunting weapon. Given that hunters will not comply voluntarily, the protection of vulnerable species can only take place through effective enforcement, for example by wildlife authorities restricting access to protected areas, or by traditional authorities restricting the sale of protected species in local markets. PMID:15615691

  13. Protective Measurement and Quantum Reality

    NASA Astrophysics Data System (ADS)

    Gao, Shan

    2015-01-01

    1. Protective measurements: an introduction Shan Gao; Part I. Fundamentals and Applications: 2. Protective measurements of the wave function of a single system Lev Vaidman; 3. Protective measurement, postselection and the Heisenberg representation Yakir Aharonov and Eliahu Cohen; 4. Protective and state measurement: a review Gennaro Auletta; 5. Determination of the stationary basis from protective measurement on a single system Lajos Diósi; 6. Weak measurements, the energy-momentum tensor and the Bohm approach Robert Flack and Basil J. Hiley; Part II. Meanings and Implications: 7. Measurement and metaphysics Peter J. Lewis; 8. Protective measurements and the explanatory gambit Michael Dickson; 9. Realism and instrumentalism about the wave function: how should we choose? Mauro Dorato and Frederico Laudisa; 10. Protective measurements and the PBR theorem Guy Hetzroni and Daniel Rohrlich; 11. The roads not taken: empty waves, waveform collapse and protective measurement in quantum theory Peter Holland; 12. Implications of protective measurements on de Broglie–Bohm trajectories Aurelien Drezet; 13. Entanglement, scaling, and the meaning of the wave function in protective measurement Maximilian Schlosshauer and Tangereen V. B. Claringbold; 14. Protective measurements and the nature of the wave function within the primitive ontology approach Vincent Lam; 15. Reality and meaning of the wave function Shan Gao; Index.

  14. Protective Measurement and Quantum Reality

    NASA Astrophysics Data System (ADS)

    Gao, Shan

    2015-01-01

    1. Protective measurements: an introduction Shan Gao; Part I. Fundamentals and Applications: 2. Protective measurements of the wave function of a single system Lev Vaidman; 3. Protective measurement, postselection and the Heisenberg representation Yakir Aharonov and Eliahu Cohen; 4. Protective and state measurement: a review Gennaro Auletta; 5. Determination of the stationary basis from protective measurement on a single system Lajos Diósi; 6. Weak measurements, the energy-momentum tensor and the Bohm approach Robert Flack and Basil J. Hiley; Part II. Meanings and Implications: 7. Measurement and metaphysics Peter J. Lewis; 8. Protective measurements and the explanatory gambit Michael Dickson; 9. Realism and instrumentalism about the wave function: how should we choose? Mauro Dorato and Frederico Laudisa; 10. Protective measurements and the PBR theorem Guy Hetzroni and Daniel Rohrlich; 11. The roads not taken: empty waves, waveform collapse and protective measurement in quantum theory Peter Holland; 12. Implications of protective measurements on de Broglie-Bohm trajectories Aurelien Drezet; 13. Entanglement, scaling, and the meaning of the wave function in protective measurement Maximilian Schlosshauer and Tangereen V. B. Claringbold; 14. Protective measurements and the nature of the wave function within the primitive ontology approach Vincent Lam; 15. Reality and meaning of the wave function Shan Gao; Index.

  15. Hierarchical multi-species modeling of carnivore responses to hunting, habitat and prey in a West African protected area.

    PubMed

    Burton, A Cole; Sam, Moses K; Balangtaa, Cletus; Brashares, Justin S

    2012-01-01

    Protected areas (PAs) are a cornerstone of global efforts to shield wildlife from anthropogenic impacts, yet their effectiveness at protecting wide-ranging species prone to human conflict--notably mammalian carnivores--is increasingly in question. An understanding of carnivore responses to human-induced and natural changes in and around PAs is critical not only to the conservation of threatened carnivore populations, but also to the effective protection of ecosystems in which they play key functional roles. However, an important challenge to assessing carnivore communities is the often infrequent and imperfect nature of survey detections. We applied a novel hierarchical multi-species occupancy model that accounted for detectability and spatial autocorrelation to data from 224 camera trap stations (sampled between October 2006 and January 2009) in order to test hypotheses about extrinsic influences on carnivore community dynamics in a West African protected area (Mole National Park, Ghana). We developed spatially explicit indices of illegal hunting activity, law enforcement patrol effort, prey biomass, and habitat productivity across the park, and used a Bayesian model selection framework to identify predictors of site occurrence for individual species and the entire carnivore community. Contrary to our expectation, hunting pressure and edge proximity did not have consistent, negative effects on occurrence across the nine carnivore species detected. Occurrence patterns for most species were positively associated with small prey biomass, and several species had either positive or negative associations with riverine forest (but not with other habitat descriptors). Influences of sampling design on carnivore detectability were also identified and addressed within our modeling framework (e.g., road and observer effects), and the multi-species approach facilitated inference on even the rarest carnivore species in the park. Our study provides insight for the conservation

  16. Hierarchical Multi-Species Modeling of Carnivore Responses to Hunting, Habitat and Prey in a West African Protected Area

    PubMed Central

    Burton, A. Cole; Sam, Moses K.; Balangtaa, Cletus; Brashares, Justin S.

    2012-01-01

    Protected areas (PAs) are a cornerstone of global efforts to shield wildlife from anthropogenic impacts, yet their effectiveness at protecting wide-ranging species prone to human conflict – notably mammalian carnivores – is increasingly in question. An understanding of carnivore responses to human-induced and natural changes in and around PAs is critical not only to the conservation of threatened carnivore populations, but also to the effective protection of ecosystems in which they play key functional roles. However, an important challenge to assessing carnivore communities is the often infrequent and imperfect nature of survey detections. We applied a novel hierarchical multi-species occupancy model that accounted for detectability and spatial autocorrelation to data from 224 camera trap stations (sampled between October 2006 and January 2009) in order to test hypotheses about extrinsic influences on carnivore community dynamics in a West African protected area (Mole National Park, Ghana). We developed spatially explicit indices of illegal hunting activity, law enforcement patrol effort, prey biomass, and habitat productivity across the park, and used a Bayesian model selection framework to identify predictors of site occurrence for individual species and the entire carnivore community. Contrary to our expectation, hunting pressure and edge proximity did not have consistent, negative effects on occurrence across the nine carnivore species detected. Occurrence patterns for most species were positively associated with small prey biomass, and several species had either positive or negative associations with riverine forest (but not with other habitat descriptors). Influences of sampling design on carnivore detectability were also identified and addressed within our modeling framework (e.g., road and observer effects), and the multi-species approach facilitated inference on even the rarest carnivore species in the park. Our study provides insight for the

  17. In situ measures of foraging success and prey encounter reveal marine habitat-dependent search strategies.

    PubMed

    Thums, Michele; Bradshaw, Corey J A; Hindelli, Mark A

    2011-06-01

    Predators are thought to reduce travel speed and increase turning rate in areas where resources are relatively more abundant, a behavior termed "area-restricted search." However, evidence for this is rare, and few empirical data exist for large predators. Animals exhibiting foraging site fidelity could also be spatially aware of suitable feeding areas based on prior experience; changes in movement patterns might therefore arise from the anticipation of higher prey density. We tested the hypothesis that regions of area-restricted search were associated with a higher number of daily speed spikes (a proxy for potential prey encounter rate) and foraging success in southern elephant seals (Mirounga leonina), a species exhibiting both area-restricted searches and high interannual foraging site fidelity. We used onshore morphological measurements and diving data from archival tags deployed during winter foraging trips. Foraging success was inferred from in situ changes in relative lipid content derived from measured changes in buoyancy, and first-passage time analysis was used to identify area-restricted search behavior. Seals exhibited relatively direct southerly movement on average, with intensive search behavior predominantly located at the distal end of tracks. The probability of being in search mode was positively related to changes in relative lipid content; thus, intensively searched areas were associated with the highest foraging success. However, there was high foraging success during the outward transit even though seals moved through quickly without slowing down and increasing turning rate to exploit these areas. In addition, the probability of being in search mode was negatively related to the number of daily speed spikes. These results suggest that movement patterns represent a response to prior expectation of the location of predictable and profitable resources. Shelf habitat was 4-9 times more profitable than the other habitats, emphasizing the importance

  18. Bats as the main prey of wintering long-eared owl (Asio otus) in Beijing: Integrating biodiversity protection and urban management.

    PubMed

    Tian, Long; Zhou, Xuwei; Shi, Yang; Guo, Yumin; Bao, Weidong

    2015-03-01

    The loss of biodiversity from urbanized areas is a major environmental problem challenging policy-makers throughout the world. Solutions to this problem are urgently required in China. We carried out a case study of wintering long-eared owls (Asio otus) and their main prey to illustrate the negative effects of urbanization combined with ineffective conservation of biodiversity in Beijing. Field monitoring of owl numbers at two roosting sites from 2004 to 2012 showed that the owl population had fallen rapidly in metropolitan Beijing. Analysis of pellet contents identified only seven individuals of two species of shrew. The majority of mammalian prey comprised four bat and seven rodent species, making up 29.3% and 29.5% of the prey items, respectively. Prey composition varied significantly among years at the two sample sites. At the urban site the consumption of bats and rodents declined gradually over time, while predation on birds increased. In contrast, at the suburban site the prey composition showed an overall decrease in the number of bats, a sharp increase and a subsequent decrease in bird prey, and the number of rodent prey fell to a low point. Rapid development of real estate and inadequate greenfield management in city parks resulted in negative effects on the bird and small mammal habitat of urban areas in Beijing. We suggest that measures to conserve biodiversity should be integrated into future urban planning to maintain China's rich biodiversity while also achieving sustainable economic development.

  19. Bats as the main prey of wintering long-eared owl (Asio otus) in Beijing: Integrating biodiversity protection and urban management.

    PubMed

    Tian, Long; Zhou, Xuwei; Shi, Yang; Guo, Yumin; Bao, Weidong

    2015-03-01

    The loss of biodiversity from urbanized areas is a major environmental problem challenging policy-makers throughout the world. Solutions to this problem are urgently required in China. We carried out a case study of wintering long-eared owls (Asio otus) and their main prey to illustrate the negative effects of urbanization combined with ineffective conservation of biodiversity in Beijing. Field monitoring of owl numbers at two roosting sites from 2004 to 2012 showed that the owl population had fallen rapidly in metropolitan Beijing. Analysis of pellet contents identified only seven individuals of two species of shrew. The majority of mammalian prey comprised four bat and seven rodent species, making up 29.3% and 29.5% of the prey items, respectively. Prey composition varied significantly among years at the two sample sites. At the urban site the consumption of bats and rodents declined gradually over time, while predation on birds increased. In contrast, at the suburban site the prey composition showed an overall decrease in the number of bats, a sharp increase and a subsequent decrease in bird prey, and the number of rodent prey fell to a low point. Rapid development of real estate and inadequate greenfield management in city parks resulted in negative effects on the bird and small mammal habitat of urban areas in Beijing. We suggest that measures to conserve biodiversity should be integrated into future urban planning to maintain China's rich biodiversity while also achieving sustainable economic development. PMID:25316405

  20. Variable wind, pack ice, and prey dispersion affect the long-term adequacy of protected areas for an Arctic sea duck.

    PubMed

    Lovvorn, James R; Anderson, Eric M; Rocha, Aariel R; Larned, William W; Grebmeier, Jacqueline M; Cooper, Lee W; Kolts, Jason M; North, Christopher A

    2014-03-01

    With changing climate, delineation of protected areas for sensitive species must account for long-term variability and geographic shifts of key habitat elements. Projecting the future adequacy of protected areas requires knowing major factors that drive such changes, and how readily the animals adjust to altered resources. In the Arctic, the viability of habitats for marine birds and mammals often depends on sea ice to dissipate storm waves and provide platforms for resting. However, some wind conditions (including weak winds during extreme cold) can consolidate pack ice into cover so dense that air-breathing divers are excluded from the better feeding areas. Spectacled Eiders (Somateria fischeri) winter among leads (openings) in pack ice in areas where densities of their bivalve prey are quite high. During winter 2009, however, prevailing winds created a large region of continuous ice with inadequate leads to allow access to areas of dense preferred prey. Stable isotope and fatty acid biomarkers indicated that, under these conditions, the eiders did not diversify their diet to include abundant non-bivalve taxa but did add a smaller, less preferred, bivalve species. Consistent with a computer model of eider energy balance, the body fat of adult eiders in 2009 was 33-35% lower than on the same date (19 March) in 2001 when ice conditions allowed access to higher bivalve densities. Ice cover data suggest that the eiders were mostly excluded from areas of high bivalve density from January to March in about 30% of 14 winters from 1998 to 2011. Thus, even without change in total extent of ice, shifts in prevailing winds can alter the areal density of ice to reduce access to important habitats. Because changes in wind-driven currents can also rearrange the dispersion of prey, the potential for altered wind patterns should be an important concern in projecting effects of climate change on the adequacy of marine protected areas for diving endotherms in the Arctic. PMID

  1. Variable wind, pack ice, and prey dispersion affect the long-term adequacy of protected areas for an Arctic sea duck.

    PubMed

    Lovvorn, James R; Anderson, Eric M; Rocha, Aariel R; Larned, William W; Grebmeier, Jacqueline M; Cooper, Lee W; Kolts, Jason M; North, Christopher A

    2014-03-01

    With changing climate, delineation of protected areas for sensitive species must account for long-term variability and geographic shifts of key habitat elements. Projecting the future adequacy of protected areas requires knowing major factors that drive such changes, and how readily the animals adjust to altered resources. In the Arctic, the viability of habitats for marine birds and mammals often depends on sea ice to dissipate storm waves and provide platforms for resting. However, some wind conditions (including weak winds during extreme cold) can consolidate pack ice into cover so dense that air-breathing divers are excluded from the better feeding areas. Spectacled Eiders (Somateria fischeri) winter among leads (openings) in pack ice in areas where densities of their bivalve prey are quite high. During winter 2009, however, prevailing winds created a large region of continuous ice with inadequate leads to allow access to areas of dense preferred prey. Stable isotope and fatty acid biomarkers indicated that, under these conditions, the eiders did not diversify their diet to include abundant non-bivalve taxa but did add a smaller, less preferred, bivalve species. Consistent with a computer model of eider energy balance, the body fat of adult eiders in 2009 was 33-35% lower than on the same date (19 March) in 2001 when ice conditions allowed access to higher bivalve densities. Ice cover data suggest that the eiders were mostly excluded from areas of high bivalve density from January to March in about 30% of 14 winters from 1998 to 2011. Thus, even without change in total extent of ice, shifts in prevailing winds can alter the areal density of ice to reduce access to important habitats. Because changes in wind-driven currents can also rearrange the dispersion of prey, the potential for altered wind patterns should be an important concern in projecting effects of climate change on the adequacy of marine protected areas for diving endotherms in the Arctic.

  2. Comparative magnetic measurements of migratory ant and its only termite prey

    NASA Astrophysics Data System (ADS)

    Esquivel, D. M. S.; Wajnberg, E.; Cernicchiaro, G. R.; Alves, O. C.

    2004-07-01

    Termites and ants are social insects living organized in nests in castes. Behavioral studies with the migratory ant Pachycondyla marginata have shown that it conducts well-organized predatory raids toward nests of its only prey, the termite Neocapritermes opacus. The magnetic materials in these two insects were studied using a SQUID magnetometer for two orientations. The Jr/ Js and Jr/ χ0, ratios were calculated from the two insects hysteresis curves. These ratios are in the range of magnetite pseudo-single or multi-domain particle values. The magnetic material are distinguishable by Hc values (30 Oe for ants and 100 Oe for termites) and by the magnetization magnitude, which is about two magnitude orders higher in the termite than in migratory ant. The Pachycondyla marginata SQUID results show an anisotropy in the magnetic material arrangement while for Neocapritermes opacus termite it is revealed by FMR spectra.

  3. Predator-prey systems depend on a prey refuge.

    PubMed

    Chivers, W J; Gladstone, W; Herbert, R D; Fuller, M M

    2014-11-01

    Models of near-exclusive predator-prey systems such as that of the Canadian lynx and snowshoe hare have included factors such as a second prey species, a Holling Type II predator response and climatic or seasonal effects to reproduce sub-sets of six signature patterns in the empirical data. We present an agent-based model which does not require the factors or constraints of previous models to reproduce all six patterns in persistent populations. Our parsimonious model represents a generalised predator and prey species with a small prey refuge. The lack of the constraints of previous models, considered to be important for those models, casts doubt on the current hypothesised mechanisms of exclusive predator-prey systems. The implication for management of the lynx, a protected species, is that maintenance of an heterogeneous environment offering natural refuge areas for the hare is the most important factor for the conservation of this species.

  4. Transient (lightning) protection for electronic measurement devices

    SciTech Connect

    Black, L.L.

    1995-12-01

    Electronic measurement devices have become a major part of the oil and gas business today. All of these devices operate on an electrical voltage. Any voltage introduced into the system that is beyond the predetermined tolerance will cause degradation of performance or in some cases failure of the device. The extent of the damage depends upon the dielectric strength of the circuit in question and upon the available energy. As electronic measurement devices are further developed to incorporate more solid state circuitry and operate at lower voltage levels the more susceptible they become to transients. Along with transient protection, the user must also be concerned with intrinsic safety requirements of the device to be protected. The devices and techniques used to protect the equipment from transients do not, in all cases, guarantee the user certification for use in hazardous environments. As a note of reference, some of the techniques listed in this paper as examples would not be allowed in hazardous areas without the addition of other devices to further isolate or clamp the available energy to a safe level. In other words, as the industry moves forward to improve the overall accuracy of the measurement system and adds data availability via communication networks, the transient protection scheme must become more sophisticated.

  5. Evaluating the connectivity of a protected areas' network under the prism of global change: the efficiency of the European Natura 2000 network for four birds of prey.

    PubMed

    Mazaris, Antonios D; Papanikolaou, Alexandra D; Barbet-Massin, Morgane; Kallimanis, Athanasios S; Jiguet, Frédéric; Schmeller, Dirk S; Pantis, John D

    2013-01-01

    Climate and land use changes are major threats to biodiversity. To preserve biodiversity, networks of protected areas have been established worldwide, like the Natura 2000 network across the European Union (EU). Currently, this reserve network consists of more than 26000 sites covering more than 17% of EU terrestrial territory. Its efficiency to mitigate the detrimental effects of land use and climate change remains an open research question. Here, we examined the potential current and future geographical ranges of four birds of prey under scenarios of both land use and climate changes. By using graph theory, we examined how the current Natura 2000 network will perform in regard to the conservation of these species. This approach determines the importance of a site in regard to the total network and its connectivity. We found that sites becoming unsuitable due to climate change are not a random sample of the network, but are less connected and contribute less to the overall connectivity than the average site and thus their loss does not disrupt the full network. Hence, the connectivity of the remaining network changed only slightly from present day conditions. Our findings highlight the need to establish species-specific management plans with flexible conservation strategies ensuring protection under potential future range expansions. Aquila pomarina is predicted to disappear from the southern part of its range and to become restricted to northeastern Europe. Gyps fulvus, Aquila chrysaetos, and Neophron percnopterus are predicted to locally lose some suitable sites; hence, some isolated small populations may become extinct. However, their geographical range and metapopulation structure will remain relatively unaffected throughout Europe. These species would benefit more from an improved habitat quality and management of the existing network of protected areas than from increased connectivity or assisted migration. PMID:23527237

  6. Evaluating the connectivity of a protected areas' network under the prism of global change: the efficiency of the European Natura 2000 network for four birds of prey.

    PubMed

    Mazaris, Antonios D; Papanikolaou, Alexandra D; Barbet-Massin, Morgane; Kallimanis, Athanasios S; Jiguet, Frédéric; Schmeller, Dirk S; Pantis, John D

    2013-01-01

    Climate and land use changes are major threats to biodiversity. To preserve biodiversity, networks of protected areas have been established worldwide, like the Natura 2000 network across the European Union (EU). Currently, this reserve network consists of more than 26000 sites covering more than 17% of EU terrestrial territory. Its efficiency to mitigate the detrimental effects of land use and climate change remains an open research question. Here, we examined the potential current and future geographical ranges of four birds of prey under scenarios of both land use and climate changes. By using graph theory, we examined how the current Natura 2000 network will perform in regard to the conservation of these species. This approach determines the importance of a site in regard to the total network and its connectivity. We found that sites becoming unsuitable due to climate change are not a random sample of the network, but are less connected and contribute less to the overall connectivity than the average site and thus their loss does not disrupt the full network. Hence, the connectivity of the remaining network changed only slightly from present day conditions. Our findings highlight the need to establish species-specific management plans with flexible conservation strategies ensuring protection under potential future range expansions. Aquila pomarina is predicted to disappear from the southern part of its range and to become restricted to northeastern Europe. Gyps fulvus, Aquila chrysaetos, and Neophron percnopterus are predicted to locally lose some suitable sites; hence, some isolated small populations may become extinct. However, their geographical range and metapopulation structure will remain relatively unaffected throughout Europe. These species would benefit more from an improved habitat quality and management of the existing network of protected areas than from increased connectivity or assisted migration.

  7. Evaluating the Connectivity of a Protected Areas' Network under the Prism of Global Change: The Efficiency of the European Natura 2000 Network for Four Birds of Prey

    PubMed Central

    Mazaris, Antonios D.; Papanikolaou, Alexandra D.; Barbet-Massin, Morgane; Kallimanis, Athanasios S.; Jiguet, Frédéric; Schmeller, Dirk S.; Pantis, John D.

    2013-01-01

    Climate and land use changes are major threats to biodiversity. To preserve biodiversity, networks of protected areas have been established worldwide, like the Natura 2000 network across the European Union (EU). Currently, this reserve network consists of more than 26000 sites covering more than 17% of EU terrestrial territory. Its efficiency to mitigate the detrimental effects of land use and climate change remains an open research question. Here, we examined the potential current and future geographical ranges of four birds of prey under scenarios of both land use and climate changes. By using graph theory, we examined how the current Natura 2000 network will perform in regard to the conservation of these species. This approach determines the importance of a site in regard to the total network and its connectivity. We found that sites becoming unsuitable due to climate change are not a random sample of the network, but are less connected and contribute less to the overall connectivity than the average site and thus their loss does not disrupt the full network. Hence, the connectivity of the remaining network changed only slightly from present day conditions. Our findings highlight the need to establish species-specific management plans with flexible conservation strategies ensuring protection under potential future range expansions. Aquila pomarina is predicted to disappear from the southern part of its range and to become restricted to northeastern Europe. Gyps fulvus, Aquila chrysaetos, and Neophron percnopterus are predicted to locally lose some suitable sites; hence, some isolated small populations may become extinct. However, their geographical range and metapopulation structure will remain relatively unaffected throughout Europe. These species would benefit more from an improved habitat quality and management of the existing network of protected areas than from increased connectivity or assisted migration. PMID:23527237

  8. Earthquake Protection Measures for People with Disabilities

    NASA Astrophysics Data System (ADS)

    Gountromichou, C.; Kourou, A.; Kerpelis, P.

    2009-04-01

    The problem of seismic safety for people with disabilities not only exists but is also urgent and of primary importance. Working towards disability equality, Earthquake Planning and Protection Organization of Greece (E.P.P.O.) has developed an educational scheme for people with disabilities in order to guide them to develop skills to protect themselves as well as to take the appropriate safety measures before, during and after an earthquake. The framework of this initiative includes a number of actions have been already undertaken, including the following: a. Recently, the main guidelines have been published to help people who have physical, cognitive, visual, or auditory disabilities to cope with a destructive earthquake. Of great importance, in case of people with disabilities, is to be prepared for the disaster, with several measures that must be taken starting today. In the pre-earthquake period, it is important that these people, in addition to other measures, do the following: - Create a Personal Support Network The Personal Support Network should be a group of at least three trustful people that can assist the disabled person to prepare for a disastrous event and to recover after it. - Complete a Personal Assessment The environment may change after a destructive earthquake. People with disabilities are encouraged to make a list of their personal needs and their resources for meeting them in a disaster environment. b. Lectures and training seminars on earthquake protection are given for students, teachers and educators in Special Schools for disabled people, mainly for informing and familiarizing them with earthquakes and with safety measures. c. Many earthquake drills have already taken place, for each disability, in order to share good practices and lessons learned to further disaster reduction and to identify gaps and challenges. The final aim of this action is all people with disabilities to be well informed and motivated towards a culture of earthquake

  9. Spatial distribution of predator/prey interactions in the Scotia Sea: implications for measuring predator/fisheries overlap

    NASA Astrophysics Data System (ADS)

    Reid, Keith; Sims, Michelle; White, Richard W.; Gillon, Keith W.

    2004-06-01

    The measurement of spatial overlap between predators and fisheries exploiting a common prey source is dependent upon the measurement scale used; inappropriate scales may produce misleading results. Previous assessments of the level of overlap between predators and fisheries for Antarctic krill ( Euphausia superba) in the region of the South Shetland Islands used different measurement scales and arrived at contradictory conclusions. At-sea data from observations of krill predators during the CCAMLR 2000 Survey were used to identify the areas of potential overlap with fisheries in the Scotia Sea and to determine the scale at which such overlap should be measured. The relationship between autocorrelation and sampling distance was used to identify the characteristic scales of the distribution of predators, krill and krill fisheries, and an effort-corrected index of relative abundance as a function of distance from land was used to identify the characteristics of areas of high potential for overlap. Despite distinct differences in foraging ecology, a group of krill-dependent species including chinstrap penguin ( Pygoscelis antarctica), (Antarctic) fur seal ( Arctocephalus sp. ( gazella)) and white-chinned petrel ( Procellaria aequinoctialis) showed similar patterns of distribution; the relative abundances were highest at 60-120 km from land and decreased sharply at distances greater than 150 km from land. There were more inter-specific differences in the characteristic scales, which were of the order of 50-100 km. Antarctic krill had a characteristic scale of approximately 200 km and the relationship with distance from land showed a log-linear decline. Krill fisheries operate at a scale of 150 km and occur almost entirely within 100 km of land. The requirement of land for breeding and the biological and oceanographic conditions that produce the high concentrations of krill associated with those land areas produce a system in which the demand for Antarctic krill from

  10. Experiments for Realising Pragmatic Protective Measurements

    SciTech Connect

    Dass, N. D. Hari

    2011-09-23

    I shall describe Aharonov, Anandan and Vaidman's proposal for protective measurements and their claims of providing an ontological interpretation for a certain class of wavefunctions through this type of measurement. I shall then describe work done with Tabish Qureshi which dispels this myth. I will show how the AAV proposal may be useful in a pragmatic sense and provide a concrete experimental setup using cold atoms. In particular, I will discuss how techniques developed by the Schmiedmayer group in Vienna for single-particle-sensitive imaging of freely propagating cold atoms could be adopted for this purpose. I will conclude with a brief description of my work with Anirban Das on adiabatic interactions between spin-systems and a proposal for its experimental realisation.

  11. 29 CFR 1917.95 - Other protective measures.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... to 46 CFR part 160 (Type I, II, III, or V PFD) and marked for use as a work vest, for commercial use... 29 Labor 7 2011-07-01 2011-07-01 false Other protective measures. 1917.95 Section 1917.95 Labor... (CONTINUED) MARINE TERMINALS Personal Protection § 1917.95 Other protective measures. (a) Protective...

  12. When Optimal Strategy Matters to Prey Fish

    PubMed Central

    Soto, Alberto; Stewart, William J.; McHenry, Matthew J.

    2015-01-01

    Predator–prey interactions are commonly studied with an interest in determining the optimal strategy for prey. However, the implications of deviating from optimal strategy are often unclear. The present study considered these consequences by studying how the direction of an escape response affects the strategy of prey fish. We simulated these interactions with numerical and analytical mathematics and compared our predictions with measurements in zebrafish larvae (Danio rerio), which are preyed upon by adults of the same species. Consistent with existing theory, we treated the minimum distance between predator and prey as the strategic payoff that prey aim to maximize. We found that these interactions may be characterized by three strategic domains that are defined by the speed of predator relative to the prey. The “fast predator” domain occurs when the predator is more than an order of magnitude faster than the prey. The escape direction of the prey had only a small effect on the minimum distance under these conditions. For the “slow predator” domain, when the prey is faster than the predator, we found that differences in direction had no effect on the minimum distance for a broad range of escape angles. This was the regime in which zebrafish were found to operate. In contrast, the optimal escape angle offers a large benefit to the minimum distance in the intermediate strategic domain. Therefore, optimal strategy is most meaningful to prey fish when predators are faster than prey by less than a factor of 10. This demonstrates that the strategy of a prey animal does not matter under certain conditions that are created by the behavior of the predator. PMID:25964496

  13. 15 CFR 764.6 - Protective administrative measures.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 15 Commerce and Foreign Trade 2 2011-01-01 2011-01-01 false Protective administrative measures. 764.6 Section 764.6 Commerce and Foreign Trade Regulations Relating to Commerce and Foreign Trade... ENFORCEMENT AND PROTECTIVE MEASURES § 764.6 Protective administrative measures. (a) License...

  14. 15 CFR 764.6 - Protective administrative measures.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 15 Commerce and Foreign Trade 2 2010-01-01 2010-01-01 false Protective administrative measures. 764.6 Section 764.6 Commerce and Foreign Trade Regulations Relating to Commerce and Foreign Trade... ENFORCEMENT AND PROTECTIVE MEASURES § 764.6 Protective administrative measures. (a) License...

  15. [Child protection measures in other countries].

    PubMed

    Hurni, L

    1980-06-01

    The goal of measures for the protection of children is to help parents to behave toward their children in physically and psychologically nonviolent ways. In this article, a distinction is made between organisations devoted to field work and those devoted to public education. Examples are given from the Netherlands, England, the United States, and the Federal Republic of Germany. The care of families at risk is often in the hands of persons having already friendly contacts with the family. This type of lay helpers receive special training, and it seems that they gain more easily access to the parents than public agencies. In several countries there are interdisciplinary therapeutic centres where children, youth, or entire families find temporary acceptance. Therapy of this type aims primarily at providing an experience of nonviolent human interaction. In public education, the accent is on information of the public. A predominant aim is a change of attitude toward violent parents, in the sense of help being more important than punishment. In most instances, there is also a need to better make known the helping organizations. Finally, some postulates for primary prevention of cruelty to children are summarized, and reference is made to the "Fourth World Movement".

  16. Protective sheath for a continuous measurement thermocouple

    DOEpatents

    Phillippi, R.M.

    1991-12-03

    Disclosed is a protective thermocouple sheath of a magnesia graphite refractory material for use in continuous temperature measurements of molten metal in a metallurgical ladle and having a basic slag layer thereon. The sheath includes an elongated torpedo-shaped sheath body formed of a refractory composition and having an interior borehole extending axially therethrough and adapted to receive a thermocouple. The sheath body includes a lower end which is closed about the borehole and forms a narrow, tapered tip. The sheath body also includes a first body portion integral with the tapered tip and having a relatively constant cross section and providing a thin wall around the borehole. The sheath body also includes a second body portion having a relatively constant cross section larger than the cross section of the first body portion and providing a thicker wall around the borehole. The borehole terminates in an open end at the second body portion. The tapered tip is adapted to penetrate the slag layer and the thicker second body portion and its magnesia constituent material are adapted to withstand chemical attack thereon from the slag layer. The graphite constituent improves thermal conductivity of the refractory material and, thus, enhances the thermal responsiveness of the device. 4 figures.

  17. Protective sheath for a continuous measurement thermocouple

    DOEpatents

    Phillippi, R. Michael

    1991-01-01

    Disclosed is a protective thermocouple sheath of a magnesia graphite refractory material for use in continuous temperature measurements of molten metal in a metallurgical ladle and having a basic slag layer thereon. The sheath includes an elongated torpedo-shaped sheath body formed of a refractory composition and having an interior borehole extending axially therethrough and adapted to receive a thermocouple. The sheath body includes a lower end which is closed about the borehole and forms a narrow, tapered tip. The sheath body also includes a first body portion integral with the tapered tip and having a relatively constant cross section and providing a thin wall around the borehole. The sheath body also includes a second body portion having a relatively constant cross section larger than the cross section of the first body portion and providing a thicker wall around the borehole. The borehole terminates in an open end at the second body portion. The tapered tip is adapted to penetrate the slag layer and the thicker second body portion and its magnesia constituent material are adapted to withstand chemical attack thereon from the slag layer. The graphite constituent improves thermal conductivity of the refractory material and, thus, enhances the thermal responsiveness of the device.

  18. 29 CFR 1918.105 - Other protective measures.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... pursuant to 46 CFR part 160 (Type I, II, III, or V PFD) and marked for use as a work vest, for commercial... 29 Labor 7 2010-07-01 2010-07-01 false Other protective measures. 1918.105 Section 1918.105 Labor... protective measures. (a) Protective clothing. (1) The employer shall provide and shall require the wearing...

  19. 29 CFR 1918.105 - Other protective measures.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... pursuant to 46 CFR part 160 (Type I, II, III, or V PFD) and marked for use as a work vest, for commercial... 29 Labor 7 2011-07-01 2011-07-01 false Other protective measures. 1918.105 Section 1918.105 Labor... protective measures. (a) Protective clothing. (1) The employer shall provide and shall require the wearing...

  20. Disentangling taste and toxicity in aposematic prey.

    PubMed

    Holen, Øistein Haugsten

    2013-02-22

    Many predators quickly learn to avoid attacking aposematic prey. If the prey vary in toxicity, the predators may alternatively learn to capture and taste-sample prey carefully before ingesting or rejecting them (go-slow behaviour). An increase in prey toxicity is generally thought to decrease predation on prey populations. However, while prey with a higher toxin load are more harmful to ingest, they may also be easier to recognize and reject owing to greater distastefulness, which can facilitate a taste-sampling foraging strategy. Here, the classic diet model is used to study the separate effects of taste and toxicity on predator preferences. The taste-sampling process is modelled using signal detection theory. The model is applicable to automimicry and batesian mimicry. It shows that when the defensive toxin is sufficiently distasteful, a mimicry complex may be less profitable to the predator and better protected against predation if the models are moderately toxic than if they are highly toxic. Moreover, taste mimicry can reduce the profitability of the mimicry complex and increase protection against predation. The results are discussed in relation to the selection pressures acting on prey defences and the evolution of mimicry.

  1. Prey vulnerability to peacock cichlids and largemouth bass based on predator gape and prey body depth

    USGS Publications Warehouse

    Hill, Jeffrey E.; Nico, Leo G.; Cichra, Charles E.; Gilbert, Carter R.

    2005-01-01

    The interaction of prey fish body depth and predator gape size may produce prey assemblages dominated by invulnerable prey and excessive prey-to-predator biomass ratios. Peacock cichlids (Cichla ocellaris) were stocked into southeast Florida canals to consume excess prey fish biomass, particularly spotted tilapia (Tilapia mariae). The ecomorphologically similar largemouth bass (Micropterus salmoides) was already present in the canals. We present relations of length-specific gape size for peacock cichlids and largemouth bass. Both predators have broadly overlapping gape size, but largemouth bass ?126 mm total length have slightly larger gape sizes than peacock cichlids of the same length. Also, we experimentally tested the predictions of maximum prey size for peacock cichlids and determined that a simple method of measuring gape size used for largemouth bass also is appropriate for peacock cichlids. Lastly, we determined relations of body depth and length of prey species to investigate relative vulnerability. Using a simple predator-prey model and length frequencies of predators and bluegill (Lepomis macrochirus), redear sunfish (Lepomis microlophus), and spotted tilapia prey, we documented that much of the prey biomass in southeast Florida canals is unavailable for largemouth bass and peacock cichlid predation.

  2. Competing conservation objectives for predators and prey: estimating killer whale prey requirements for Chinook salmon.

    PubMed

    Williams, Rob; Krkošek, Martin; Ashe, Erin; Branch, Trevor A; Clark, Steve; Hammond, Philip S; Hoyt, Erich; Noren, Dawn P; Rosen, David; Winship, Arliss

    2011-01-01

    Ecosystem-based management (EBM) of marine resources attempts to conserve interacting species. In contrast to single-species fisheries management, EBM aims to identify and resolve conflicting objectives for different species. Such a conflict may be emerging in the northeastern Pacific for southern resident killer whales (Orcinus orca) and their primary prey, Chinook salmon (Oncorhynchus tshawytscha). Both species have at-risk conservation status and transboundary (Canada-US) ranges. We modeled individual killer whale prey requirements from feeding and growth records of captive killer whales and morphometric data from historic live-capture fishery and whaling records worldwide. The models, combined with caloric value of salmon, and demographic and diet data for wild killer whales, allow us to predict salmon quantities needed to maintain and recover this killer whale population, which numbered 87 individuals in 2009. Our analyses provide new information on cost of lactation and new parameter estimates for other killer whale populations globally. Prey requirements of southern resident killer whales are difficult to reconcile with fisheries and conservation objectives for Chinook salmon, because the number of fish required is large relative to annual returns and fishery catches. For instance, a U.S. recovery goal (2.3% annual population growth of killer whales over 28 years) implies a 75% increase in energetic requirements. Reducing salmon fisheries may serve as a temporary mitigation measure to allow time for management actions to improve salmon productivity to take effect. As ecosystem-based fishery management becomes more prevalent, trade-offs between conservation objectives for predators and prey will become increasingly necessary. Our approach offers scenarios to compare relative influence of various sources of uncertainty on the resulting consumption estimates to prioritise future research efforts, and a general approach for assessing the extent of conflict

  3. Competing Conservation Objectives for Predators and Prey: Estimating Killer Whale Prey Requirements for Chinook Salmon

    PubMed Central

    Williams, Rob; Krkošek, Martin; Ashe, Erin; Branch, Trevor A.; Clark, Steve; Hammond, Philip S.; Hoyt, Erich; Noren, Dawn P.; Rosen, David; Winship, Arliss

    2011-01-01

    Ecosystem-based management (EBM) of marine resources attempts to conserve interacting species. In contrast to single-species fisheries management, EBM aims to identify and resolve conflicting objectives for different species. Such a conflict may be emerging in the northeastern Pacific for southern resident killer whales (Orcinus orca) and their primary prey, Chinook salmon (Oncorhynchus tshawytscha). Both species have at-risk conservation status and transboundary (Canada–US) ranges. We modeled individual killer whale prey requirements from feeding and growth records of captive killer whales and morphometric data from historic live-capture fishery and whaling records worldwide. The models, combined with caloric value of salmon, and demographic and diet data for wild killer whales, allow us to predict salmon quantities needed to maintain and recover this killer whale population, which numbered 87 individuals in 2009. Our analyses provide new information on cost of lactation and new parameter estimates for other killer whale populations globally. Prey requirements of southern resident killer whales are difficult to reconcile with fisheries and conservation objectives for Chinook salmon, because the number of fish required is large relative to annual returns and fishery catches. For instance, a U.S. recovery goal (2.3% annual population growth of killer whales over 28 years) implies a 75% increase in energetic requirements. Reducing salmon fisheries may serve as a temporary mitigation measure to allow time for management actions to improve salmon productivity to take effect. As ecosystem-based fishery management becomes more prevalent, trade-offs between conservation objectives for predators and prey will become increasingly necessary. Our approach offers scenarios to compare relative influence of various sources of uncertainty on the resulting consumption estimates to prioritise future research efforts, and a general approach for assessing the extent of conflict

  4. Gluttonous predators: how to estimate prey size when there are too many prey.

    PubMed

    Araújo, M S; Pinheiro, A; Reis, S F

    2008-05-01

    Prey size is an important factor in food consumption. In studies of feeding ecology, prey items are usually measured individually using calipers or ocular micrometers. Among amphibians and reptiles, there are species that feed on large numbers of small prey items (e.g. ants, termites). This high intake makes it difficult to estimate prey size consumed by these animals. We addressed this problem by developing and evaluating a procedure for subsampling the stomach contents of such predators in order to estimate prey size. Specifically, we developed a protocol based on a bootstrap procedure to obtain a subsample with a precision error of at the most 5%, with a confidence level of at least 95%. This guideline should reduce the sampling effort and facilitate future studies on the feeding habits of amphibians and reptiles, and also provide a means of obtaining precise estimates of prey size. PMID:18660959

  5. 30 CFR 282.28 - Environmental protection measures.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false Environmental protection measures. 282.28 Section 282.28 Mineral Resources MINERALS MANAGEMENT SERVICE, DEPARTMENT OF THE INTERIOR OFFSHORE... Responsibilities of Lessees § 282.28 Environmental protection measures. (a) Exploration, testing,...

  6. 46 CFR Sec. 5 - Measures to protect ship's payrolls.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 8 2012-10-01 2012-10-01 false Measures to protect ship's payrolls. Sec. 5 Section 5 Shipping MARITIME ADMINISTRATION, DEPARTMENT OF TRANSPORTATION A-NATIONAL SHIPPING AUTHORITY BONDING OF SHIP'S PERSONNEL Sec. 5 Measures to protect ship's payrolls. (a) General Agents are not required...

  7. 46 CFR Sec. 5 - Measures to protect ship's payrolls.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 8 2013-10-01 2013-10-01 false Measures to protect ship's payrolls. Sec. 5 Section 5... SHIP'S PERSONNEL Sec. 5 Measures to protect ship's payrolls. (a) General Agents are not required to... paying off the crew should be either the Master, or purser, or some other member of the ship's...

  8. 46 CFR Sec. 5 - Measures to protect ship's payrolls.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 8 2010-10-01 2010-10-01 false Measures to protect ship's payrolls. Sec. 5 Section 5... SHIP'S PERSONNEL Sec. 5 Measures to protect ship's payrolls. (a) General Agents are not required to... paying off the crew should be either the Master, or purser, or some other member of the ship's...

  9. 46 CFR Sec. 5 - Measures to protect ship's payrolls.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 8 2011-10-01 2011-10-01 false Measures to protect ship's payrolls. Sec. 5 Section 5... SHIP'S PERSONNEL Sec. 5 Measures to protect ship's payrolls. (a) General Agents are not required to... paying off the crew should be either the Master, or purser, or some other member of the ship's...

  10. 46 CFR Sec. 5 - Measures to protect ship's payrolls.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 8 2014-10-01 2014-10-01 false Measures to protect ship's payrolls. Sec. 5 Section 5... SHIP'S PERSONNEL Sec. 5 Measures to protect ship's payrolls. (a) General Agents are not required to... paying off the crew should be either the Master, or purser, or some other member of the ship's...

  11. Measuring the effectiveness of protected area networks in reducing deforestation

    PubMed Central

    Andam, Kwaw S.; Ferraro, Paul J.; Pfaff, Alexander; Sanchez-Azofeifa, G. Arturo; Robalino, Juan A.

    2008-01-01

    Global efforts to reduce tropical deforestation rely heavily on the establishment of protected areas. Measuring the effectiveness of these areas is difficult because the amount of deforestation that would have occurred in the absence of legal protection cannot be directly observed. Conventional methods of evaluating the effectiveness of protected areas can be biased because protection is not randomly assigned and because protection can induce deforestation spillovers (displacement) to neighboring forests. We demonstrate that estimates of effectiveness can be substantially improved by controlling for biases along dimensions that are observable, measuring spatial spillovers, and testing the sensitivity of estimates to potential hidden biases. We apply matching methods to evaluate the impact on deforestation of Costa Rica's renowned protected-area system between 1960 and 1997. We find that protection reduced deforestation: approximately 10% of the protected forests would have been deforested had they not been protected. Conventional approaches to evaluating conservation impact, which fail to control for observable covariates correlated with both protection and deforestation, substantially overestimate avoided deforestation (by over 65%, based on our estimates). We also find that deforestation spillovers from protected to unprotected forests are negligible. Our conclusions are robust to potential hidden bias, as well as to changes in modeling assumptions. Our results show that, with appropriate empirical methods, conservation scientists and policy makers can better understand the relationships between human and natural systems and can use this to guide their attempts to protect critical ecosystem services. PMID:18854414

  12. Measuring the effectiveness of protected area networks in reducing deforestation.

    PubMed

    Andam, Kwaw S; Ferraro, Paul J; Pfaff, Alexander; Sanchez-Azofeifa, G Arturo; Robalino, Juan A

    2008-10-21

    Global efforts to reduce tropical deforestation rely heavily on the establishment of protected areas. Measuring the effectiveness of these areas is difficult because the amount of deforestation that would have occurred in the absence of legal protection cannot be directly observed. Conventional methods of evaluating the effectiveness of protected areas can be biased because protection is not randomly assigned and because protection can induce deforestation spillovers (displacement) to neighboring forests. We demonstrate that estimates of effectiveness can be substantially improved by controlling for biases along dimensions that are observable, measuring spatial spillovers, and testing the sensitivity of estimates to potential hidden biases. We apply matching methods to evaluate the impact on deforestation of Costa Rica's renowned protected-area system between 1960 and 1997. We find that protection reduced deforestation: approximately 10% of the protected forests would have been deforested had they not been protected. Conventional approaches to evaluating conservation impact, which fail to control for observable covariates correlated with both protection and deforestation, substantially overestimate avoided deforestation (by over 65%, based on our estimates). We also find that deforestation spillovers from protected to unprotected forests are negligible. Our conclusions are robust to potential hidden bias, as well as to changes in modeling assumptions. Our results show that, with appropriate empirical methods, conservation scientists and policy makers can better understand the relationships between human and natural systems and can use this to guide their attempts to protect critical ecosystem services.

  13. Quantum state and quantum entanglement protection using quantum measurements

    NASA Astrophysics Data System (ADS)

    Wang, Shuchao; Li, Ying; Wang, Xiangbin; Kwek, Leong Chuan; Yu, Zongwen; Zou, Wenjie

    2015-03-01

    The time evolution of some quantum states can be slowed down or even stopped under frequent measurements. This is the usual quantum Zeno effect. Here we report an operator quantum Zeno effect, in which the evolution of some physical observables is slowed down through measurements even though thequantum state changes randomly with time. Based on the operator quantum Zeno effect, we show how we can protect quantum information from decoherence with two-qubit measurements, realizable with noisy two-qubit interactions. Besides, we report the quantum entanglement protection using weak measurement and measurement reversal scheme. Exposed in the nonzero temperature environment, a quantum system can both lose and gain excitations by interacting with the environment. In this work, we show how to optimally protect quantum states and quantum entanglement in such a situation based on measurement reversal from weak measurement. In particular, we present explicit formulas of protection. We find that this scheme can circumvent the entanglement sudden death in certain conditions.

  14. Protecting weak measurements against systematic errors

    NASA Astrophysics Data System (ADS)

    Pang, Shengshi; Alonso, Jose Raul Gonzalez; Brun, Todd A.; Jordan, Andrew N.

    2016-07-01

    In this work, we consider the systematic error of quantum metrology by weak measurements under decoherence. We derive the systematic error of maximum likelihood estimation in general to the first-order approximation of a small deviation in the probability distribution and study the robustness of standard weak measurement and postselected weak measurements against systematic errors. We show that, with a large weak value, the systematic error of a postselected weak measurement when the probe undergoes decoherence can be significantly lower than that of a standard weak measurement. This indicates another advantage of weak-value amplification in improving the performance of parameter estimation. We illustrate the results by an exact numerical simulation of decoherence arising from a bosonic mode and compare it to the first-order analytical result we obtain.

  15. A single predator multiple prey model with prey mutation

    NASA Astrophysics Data System (ADS)

    Mullan, Rory; Abernethy, Gavin M.; Glass, David H.; McCartney, Mark

    2016-11-01

    A multiple species predator-prey model is expanded with the introduction of a coupled map lattice for the prey, allowing the prey to mutate discretely into other prey species. The model is examined in its single predator, multiple mutating prey form. Two unimodal maps are used for the underlying dynamics of the prey species, with different predation strategies being used. Conclusions are drawn on how varying the control parameters of the model governs the overall behaviour and survival of the species. It is observed that in such a complex system, with multiple mutating prey, a large range of non-linear dynamics is possible.

  16. Predators and Prey

    ERIC Educational Resources Information Center

    Kramm, Kenneth R.

    1975-01-01

    Reviews basic concepts of predator-prey interaction, encourages the presentation of the predator's role and describes a model of predator behavior to be used in secondary school or college classes. (LS)

  17. SITE-SPECIFIC MEASUREMENTS OF RESIDENTIAL RADON PROTECTION CATEGORY

    EPA Science Inventory

    The report describes a series of benchmark measurements of soil radon potential at seven Florida sites and compares the measurements with regional estimates of radon potential from the Florida radon protection map. The measurements and map were developed under the Florida Radon R...

  18. Sustainability and economic consequences of creating marine protected areas in multispecies multiactivity context.

    PubMed

    Kar, T K; Ghosh, Bapan

    2013-02-01

    The present study deals with harvesting of prey species in the presence of predator in a multispecies marine fishery. The total habitat is divided into two patches: one is reserve area where fishing is completely banned and other zone is called fishing area where only prey is exploited. We assume that the prey fish possesses heterogeneous intrinsic growth rate with uniform carrying capacity where as predator has constant intrinsic growth rate with prey dependent carrying capacity. The analytical conditions are derived to prevent the species extinction for larger employed effort in single (only prey) species fishery. Optimal equilibrium premium are presented for both monospecies and multispecies fishery for all degree of protection. Increasing standing stock (ISS) and protected standing stock (PSS) are measured in the presence of prey-predator interaction.

  19. Sustainability and economic consequences of creating marine protected areas in multispecies multiactivity context.

    PubMed

    Kar, T K; Ghosh, Bapan

    2013-02-01

    The present study deals with harvesting of prey species in the presence of predator in a multispecies marine fishery. The total habitat is divided into two patches: one is reserve area where fishing is completely banned and other zone is called fishing area where only prey is exploited. We assume that the prey fish possesses heterogeneous intrinsic growth rate with uniform carrying capacity where as predator has constant intrinsic growth rate with prey dependent carrying capacity. The analytical conditions are derived to prevent the species extinction for larger employed effort in single (only prey) species fishery. Optimal equilibrium premium are presented for both monospecies and multispecies fishery for all degree of protection. Increasing standing stock (ISS) and protected standing stock (PSS) are measured in the presence of prey-predator interaction. PMID:23149287

  20. Adult Prey Neutralizes Predator Nonconsumptive Limitation of Prey Recruitment

    PubMed Central

    Scrosati, Ricardo A.; Romoth, Katharina; Molis, Markus

    2016-01-01

    Recent studies have shown that predator chemical cues can limit prey demographic rates such as recruitment. For instance, barnacle pelagic larvae reduce settlement where predatory dogwhelk cues are detected, thereby limiting benthic recruitment. However, adult barnacles attract conspecific larvae through chemical and visual cues, aiding larvae to find suitable habitat for development. Thus, we tested the hypothesis that the presence of adult barnacles (Semibalanus balanoides) can neutralize dogwhelk (Nucella lapillus) nonconsumptive effects on barnacle recruitment. We did a field experiment in Atlantic Canada during the 2012 and 2013 barnacle recruitment seasons (May–June). We manipulated the presence of dogwhelks (without allowing them to physically contact barnacles) and adult barnacles in cages established in rocky intertidal habitats. At the end of both recruitment seasons, we measured barnacle recruit density on tiles kept inside the cages. Without adult barnacles, the nearby presence of dogwhelks limited barnacle recruitment by 51%. However, the presence of adult barnacles increased barnacle recruitment by 44% and neutralized dogwhelk nonconsumptive effects on barnacle recruitment, as recruit density was unaffected by dogwhelk presence. For species from several invertebrate phyla, benthic adult organisms attract conspecific pelagic larvae. Thus, adult prey might commonly constitute a key factor preventing negative predator nonconsumptive effects on prey recruitment. PMID:27123994

  1. Adult Prey Neutralizes Predator Nonconsumptive Limitation of Prey Recruitment.

    PubMed

    Ellrich, Julius A; Scrosati, Ricardo A; Romoth, Katharina; Molis, Markus

    2016-01-01

    Recent studies have shown that predator chemical cues can limit prey demographic rates such as recruitment. For instance, barnacle pelagic larvae reduce settlement where predatory dogwhelk cues are detected, thereby limiting benthic recruitment. However, adult barnacles attract conspecific larvae through chemical and visual cues, aiding larvae to find suitable habitat for development. Thus, we tested the hypothesis that the presence of adult barnacles (Semibalanus balanoides) can neutralize dogwhelk (Nucella lapillus) nonconsumptive effects on barnacle recruitment. We did a field experiment in Atlantic Canada during the 2012 and 2013 barnacle recruitment seasons (May-June). We manipulated the presence of dogwhelks (without allowing them to physically contact barnacles) and adult barnacles in cages established in rocky intertidal habitats. At the end of both recruitment seasons, we measured barnacle recruit density on tiles kept inside the cages. Without adult barnacles, the nearby presence of dogwhelks limited barnacle recruitment by 51%. However, the presence of adult barnacles increased barnacle recruitment by 44% and neutralized dogwhelk nonconsumptive effects on barnacle recruitment, as recruit density was unaffected by dogwhelk presence. For species from several invertebrate phyla, benthic adult organisms attract conspecific pelagic larvae. Thus, adult prey might commonly constitute a key factor preventing negative predator nonconsumptive effects on prey recruitment.

  2. Adult Prey Neutralizes Predator Nonconsumptive Limitation of Prey Recruitment.

    PubMed

    Ellrich, Julius A; Scrosati, Ricardo A; Romoth, Katharina; Molis, Markus

    2016-01-01

    Recent studies have shown that predator chemical cues can limit prey demographic rates such as recruitment. For instance, barnacle pelagic larvae reduce settlement where predatory dogwhelk cues are detected, thereby limiting benthic recruitment. However, adult barnacles attract conspecific larvae through chemical and visual cues, aiding larvae to find suitable habitat for development. Thus, we tested the hypothesis that the presence of adult barnacles (Semibalanus balanoides) can neutralize dogwhelk (Nucella lapillus) nonconsumptive effects on barnacle recruitment. We did a field experiment in Atlantic Canada during the 2012 and 2013 barnacle recruitment seasons (May-June). We manipulated the presence of dogwhelks (without allowing them to physically contact barnacles) and adult barnacles in cages established in rocky intertidal habitats. At the end of both recruitment seasons, we measured barnacle recruit density on tiles kept inside the cages. Without adult barnacles, the nearby presence of dogwhelks limited barnacle recruitment by 51%. However, the presence of adult barnacles increased barnacle recruitment by 44% and neutralized dogwhelk nonconsumptive effects on barnacle recruitment, as recruit density was unaffected by dogwhelk presence. For species from several invertebrate phyla, benthic adult organisms attract conspecific pelagic larvae. Thus, adult prey might commonly constitute a key factor preventing negative predator nonconsumptive effects on prey recruitment. PMID:27123994

  3. Protection of leukemic cells by deoxycytidine: in vitro measures of protection against cytosine arabinoside.

    PubMed

    Cohen, J D; Strock, D J; LaGuardia, E A; Mao, Z; Teik, J E

    1998-05-01

    Plasma deoxycytidine levels can be very high in leukemia patients. Such levels strongly protected leukemia cell lines against cytosine arabinoside (araC), fludarabine and 2-chlorodeoxyadenosine when using clonogenic survival as the endpoint. This endpoint is not easily used when studying protection in clinical leukemia cell samples. Therefore, we tested other ways to quantify protection based on biochemical measures of viability or drug metabolism. The estimates of the strength of protection based on rates of DNA synthesis, cellular araC uptake and incorporation of araC into DNA were much lower than the estimates using clonogenic survival. The MTT viability assay gave excellent estimates and appears promising for studying protection in primary leukemia cell samples.

  4. Public-private provision of protection measures against natural hazards

    NASA Astrophysics Data System (ADS)

    Gruber, M.

    2009-04-01

    Natural hazards threaten human lives as well as economic values of a society. Due to an increasing population density, augmenting property holdings in congested areas as well as higher frequencies of catastrophic events, the damage potential associated with natural hazards is growing. In order to safeguard societal assets against this threat, active and passive protection measures can be established. While passive protection measures provide for this type of risk by means of thorough land use planning, active protection measures aim at improving safety through technical or biological protective systems and structures. However, these provisions are costly and need to be handled prudentially. In most European countries protection measures against natural hazards are provided by the public. Specific governmental funds have been set up for the establishment of preventive systems as well as for damage compensation payments after the occurrence of catastrophic events. Though, additional capital is urgently needed in order to facilitate the realisation of all necessary projects in this field and to provide for maximal safety. One potential solution for such financial deficiencies can be found in Public Private Partnerships (PPP). PPPs have been implemented as attractive concepts for the funding of diverse projects in the fields of e.g. road construction, municipal, health and social services. In principle, they could also provide alternative funding solutions for the establishment of crucial protective infrastructure in respect of natural hazards, adding private financial means to the currently available public funds. Thereby, the entire capacities for catastrophe funding could be enhanced. Beside PPPs, also alternative funding mechanisms such as the emission of catastrophe bonds, contingent credit lines or leasing arrangements may enhance available capacities for the financing of protection measures. This contribution discusses innovative solutions for the funding of

  5. A dinoflagellate exploits toxins to immobilize prey prior to ingestion.

    PubMed

    Sheng, Jian; Malkiel, Edwin; Katz, Joseph; Adolf, Jason E; Place, Allen R

    2010-02-01

    Toxins produced by the harmful algal bloom (HAB) forming, mixotrophic dinoflagellate Karlodinium veneficum have long been associated with fish kills. To date, the perceived ecological role for toxins has been relief from grazing pressures. Here, we demonstrate that karlotoxins also serve as a predation instrument. Using high-speed holographic microscopy, we measure the swimming behavior of several toxic and nontoxic strains of K. veneficum and their prey, Storeatula major, within dense suspensions. The selected strains produce toxins with varying potency and dosages, including a nontoxic one. Results clearly show that mixing the prey with the predatory, toxic strains causes prey immobilization at rates that are consistent with the karlotoxins' potency and dosage. Even prey cells that continue swimming slow down after exposure to toxic predators. The swimming characteristics of predators vary substantially in pure suspensions, as quantified by their velocity, radii of helical trajectories, and direction of helical rotation. When mixed with prey, all toxic strains that are involved in predation slow down. Furthermore, they substantially reduced their predominantly vertical migration, presumably to remain in the vicinity of their prey. Conversely, the nontoxic control strain does not alter its swimming and does not affect prey behavior. In separate experiments, we show that exposing prey to exogenous toxins also causes prey immobilization at rates consistent with potency. Clearly, the toxic predatory strains use karlotoxins as a means of stunning their prey, before ingesting it. These findings add a substantiated critical understanding for why some HAB species produce such complex toxin molecules.

  6. L-shaped prey isocline in the Gause predator-prey experiments with a prey refuge.

    PubMed

    Křivan, Vlastimil; Priyadarshi, Anupam

    2015-04-01

    Predator and prey isoclines are estimated from data on yeast-protist population dynamics (Gause et al., 1936). Regression analysis shows that the prey isocline is best fitted by an L-shaped function that has a vertical and a horizontal part. The predator isocline is vertical. This shape of isoclines corresponds with the Lotka-Volterra and the Rosenzweig-MacArthur predator-prey models that assume a prey refuge. These results further support the idea that a prey refuge changes the prey isocline of predator-prey models from a horizontal to an L-shaped curve. Such a shape of the prey isocline effectively bounds amplitude of predator-prey oscillations, thus promotes species coexistence.

  7. L-shaped prey isocline in the Gause predator-prey experiments with a prey refuge.

    PubMed

    Křivan, Vlastimil; Priyadarshi, Anupam

    2015-04-01

    Predator and prey isoclines are estimated from data on yeast-protist population dynamics (Gause et al., 1936). Regression analysis shows that the prey isocline is best fitted by an L-shaped function that has a vertical and a horizontal part. The predator isocline is vertical. This shape of isoclines corresponds with the Lotka-Volterra and the Rosenzweig-MacArthur predator-prey models that assume a prey refuge. These results further support the idea that a prey refuge changes the prey isocline of predator-prey models from a horizontal to an L-shaped curve. Such a shape of the prey isocline effectively bounds amplitude of predator-prey oscillations, thus promotes species coexistence. PMID:25644756

  8. Effect of light, prey density, and prey type on the feeding rates of Hemimysis anomala

    USGS Publications Warehouse

    Halpin, Kathleen E.; Boscarino, Brent T.; Rudstam, Lars G.; Walsh, Mureen G.; Lantry, Brian F.

    2013-01-01

    Hemimysis anomala is a near-shore mysid native to the Ponto-Caspian region that was discovered to have invaded Great Lakes ecosystems in 2006. We investigated feeding rates and prey preferences of adult and juvenile Hemimysis in laboratory experiments to gain insight on the potential for Hemimysis to disrupt food webs. For both age groups (AGs), we measured feeding rates as a function of prey abundance (Bosmina longirostris as prey), prey type (B. longirostris, Daphnia pulex, and Mesocyclops sp.), and light levels (no light and dim light). Mean feeding rates on Bosmina increased with prey density and reached 23 ind. (2 h)−1 for adults and 17 ind. (2 h)−1 for juveniles. Dim light had little effect on prey selection or feeding rate compared to complete darkness. When feeding rates on alternate prey were compared, both AGs fed at higher rates on Bosmina than Daphnia, but only juveniles fed at significantly higher rates on Bosmina relative to Mesocyclops. No significant differences were observed between feeding rates on Mesocyclops and on Daphnia. Hemimysis feeding rates were on the order of 30–60% of their body weight per day, similar to predatory cladocerans that have been implicated in zooplankton declines in Lakes Huron and Ontario.

  9. Personal Protection Measures Against Mosquitoes, Ticks, and Other Arthropods.

    PubMed

    Alpern, Jonathan D; Dunlop, Stephen J; Dolan, Benjamin J; Stauffer, William M; Boulware, David R

    2016-03-01

    Arthropod-associated diseases are a major cause of morbidity among travelers. Obtaining a detailed travel itinerary and understanding traveler-specific and destination-specific risk factors can help mitigate the risk of vector-borne diseases. DEET, picaridin, PMD, and IR3535 are insect repellents that offer sufficient protection against arthropod bites. IR3535 does not provide adequate protection against Anopheles mosquitoes, and should be avoided in malaria-endemic regions. General protective measures, such as bite avoidance, protective clothing, insecticide-treated bed nets, and insecticide-treated clothing, should be recommended, especially in malaria-endemic areas. Spatial repellents may prevent nuisance biting, but have not been shown to prevent against vector-borne disease.

  10. Personal Protection Measures Against Mosquitoes, Ticks, and Other Arthropods.

    PubMed

    Alpern, Jonathan D; Dunlop, Stephen J; Dolan, Benjamin J; Stauffer, William M; Boulware, David R

    2016-03-01

    Arthropod-associated diseases are a major cause of morbidity among travelers. Obtaining a detailed travel itinerary and understanding traveler-specific and destination-specific risk factors can help mitigate the risk of vector-borne diseases. DEET, picaridin, PMD, and IR3535 are insect repellents that offer sufficient protection against arthropod bites. IR3535 does not provide adequate protection against Anopheles mosquitoes, and should be avoided in malaria-endemic regions. General protective measures, such as bite avoidance, protective clothing, insecticide-treated bed nets, and insecticide-treated clothing, should be recommended, especially in malaria-endemic areas. Spatial repellents may prevent nuisance biting, but have not been shown to prevent against vector-borne disease. PMID:26900115

  11. Load Measurement on Foundations of Rockfall Protection Systems.

    PubMed

    Volkwein, Axel; Kummer, Peter; Bitnel, Hueseyin; Campana, Lorenzo

    2016-01-01

    Rockfall protection barriers are connected to the ground using steel cables fixed with anchors and foundations for the steel posts. It is common practice to measure the forces in the cables, while to date measurements of forces in the foundations have been inadequately resolved. An overview is presented of existing methods to measure the loads on the post foundations of rockfall protection barriers. Addressing some of the inadequacies of existing approaches, a novel sensor unit is presented that is able to capture the forces acting on post foundations in all six degrees of freedom. The sensor unit consists of four triaxial force sensors placed between two steel plates. To correctly convert the measurements into the directional forces acting on the foundation a special in-situ calibration procedure is proposed that delivers a corresponding conversion matrix. PMID:26840315

  12. Load Measurement on Foundations of Rockfall Protection Systems

    PubMed Central

    Volkwein, Axel; Kummer, Peter; Bitnel, Hueseyin; Campana, Lorenzo

    2016-01-01

    Rockfall protection barriers are connected to the ground using steel cables fixed with anchors and foundations for the steel posts. It is common practice to measure the forces in the cables, while to date measurements of forces in the foundations have been inadequately resolved. An overview is presented of existing methods to measure the loads on the post foundations of rockfall protection barriers. Addressing some of the inadequacies of existing approaches, a novel sensor unit is presented that is able to capture the forces acting on post foundations in all six degrees of freedom. The sensor unit consists of four triaxial force sensors placed between two steel plates. To correctly convert the measurements into the directional forces acting on the foundation a special in-situ calibration procedure is proposed that delivers a corresponding conversion matrix. PMID:26840315

  13. 30 CFR 582.28 - Environmental protection measures.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Section 582.28 Mineral Resources BUREAU OF OCEAN ENERGY MANAGEMENT, DEPARTMENT OF THE INTERIOR OFFSHORE... Responsibilities of Lessees § 582.28 Environmental protection measures. (a) Exploration, testing, development... consequences of proposed OCS activities will follow the practices and procedures specified in 30 CFR...

  14. 30 CFR 582.28 - Environmental protection measures.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Section 582.28 Mineral Resources BUREAU OF OCEAN ENERGY MANAGEMENT, DEPARTMENT OF THE INTERIOR OFFSHORE... Responsibilities of Lessees § 582.28 Environmental protection measures. (a) Exploration, testing, development... consequences of proposed OCS activities will follow the practices and procedures specified in 30 CFR...

  15. 30 CFR 582.28 - Environmental protection measures.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Section 582.28 Mineral Resources BUREAU OF OCEAN ENERGY MANAGEMENT, DEPARTMENT OF THE INTERIOR OFFSHORE... Responsibilities of Lessees § 582.28 Environmental protection measures. (a) Exploration, testing, development... consequences of proposed OCS activities will follow the practices and procedures specified in 30 CFR...

  16. 50 CFR 622.29 - Conservation measures for protected resources.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... protected resources. (a) Gulf reef fish commercial vessels and charter vessels/headboats—(1) Sea turtle... if no wheelhouse, the sea turtle handling and release guidelines provided by NMFS. (ii) Such owner or operator must also comply with the sea turtle bycatch mitigation measures, including gear requirements...

  17. 50 CFR 622.29 - Conservation measures for protected resources.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... protected resources. (a) Gulf reef fish commercial vessels and charter vessels/headboats—(1) Sea turtle... if no wheelhouse, the sea turtle handling and release guidelines provided by NMFS. (ii) Such owner or operator must also comply with the sea turtle bycatch mitigation measures, including gear requirements...

  18. Human activity helps prey win the predator-prey space race.

    PubMed

    Muhly, Tyler B; Semeniuk, Christina; Massolo, Alessandro; Hickman, Laura; Musiani, Marco

    2011-01-01

    Predator-prey interactions, including between large mammalian wildlife species, can be represented as a "space race", where prey try to minimize and predators maximize spatial overlap. Human activity can also influence the distribution of wildlife species. In particular, high-human disturbance can displace large carnivore predators, a trait-mediated direct effect. Predator displacement by humans could then indirectly benefit prey species by reducing predation risk, a trait-mediated indirect effect of humans that spatially decouples predators from prey. The purpose of this research was to test the hypothesis that high-human activity was displacing predators and thus indirectly creating spatial refuge for prey species, helping prey win the "space race". We measured the occurrence of eleven large mammal species (including humans and cattle) at 43 camera traps deployed on roads and trails in southwest Alberta, Canada. We tested species co-occurrence at camera sites using hierarchical cluster and nonmetric multidimensional scaling (NMS) analyses; and tested whether human activity, food and/or habitat influenced predator and prey species counts at camera sites using regression tree analysis. Cluster and NMS analysis indicated that at camera sites humans co-occurred with prey species more than predator species and predator species had relatively low co-occurrence with prey species. Regression tree analysis indicated that prey species were three times more abundant on roads and trails with >32 humans/day. However, predators were less abundant on roads and trails that exceeded 18 humans/day. Our results support the hypothesis that high-human activity displaced predators but not prey species, creating spatial refuge from predation. High-human activity on roads and trails (i.e., >18 humans/day) has the potential to interfere with predator-prey interactions via trait-mediated direct and indirect effects. We urge scientist and managers to carefully consider and quantify the

  19. Human activity helps prey win the predator-prey space race.

    PubMed

    Muhly, Tyler B; Semeniuk, Christina; Massolo, Alessandro; Hickman, Laura; Musiani, Marco

    2011-03-02

    Predator-prey interactions, including between large mammalian wildlife species, can be represented as a "space race", where prey try to minimize and predators maximize spatial overlap. Human activity can also influence the distribution of wildlife species. In particular, high-human disturbance can displace large carnivore predators, a trait-mediated direct effect. Predator displacement by humans could then indirectly benefit prey species by reducing predation risk, a trait-mediated indirect effect of humans that spatially decouples predators from prey. The purpose of this research was to test the hypothesis that high-human activity was displacing predators and thus indirectly creating spatial refuge for prey species, helping prey win the "space race". We measured the occurrence of eleven large mammal species (including humans and cattle) at 43 camera traps deployed on roads and trails in southwest Alberta, Canada. We tested species co-occurrence at camera sites using hierarchical cluster and nonmetric multidimensional scaling (NMS) analyses; and tested whether human activity, food and/or habitat influenced predator and prey species counts at camera sites using regression tree analysis. Cluster and NMS analysis indicated that at camera sites humans co-occurred with prey species more than predator species and predator species had relatively low co-occurrence with prey species. Regression tree analysis indicated that prey species were three times more abundant on roads and trails with >32 humans/day. However, predators were less abundant on roads and trails that exceeded 18 humans/day. Our results support the hypothesis that high-human activity displaced predators but not prey species, creating spatial refuge from predation. High-human activity on roads and trails (i.e., >18 humans/day) has the potential to interfere with predator-prey interactions via trait-mediated direct and indirect effects. We urge scientist and managers to carefully consider and quantify the

  20. Human Activity Helps Prey Win the Predator-Prey Space Race

    PubMed Central

    Muhly, Tyler B.; Semeniuk, Christina; Massolo, Alessandro; Hickman, Laura; Musiani, Marco

    2011-01-01

    Predator-prey interactions, including between large mammalian wildlife species, can be represented as a “space race”, where prey try to minimize and predators maximize spatial overlap. Human activity can also influence the distribution of wildlife species. In particular, high-human disturbance can displace large carnivore predators, a trait-mediated direct effect. Predator displacement by humans could then indirectly benefit prey species by reducing predation risk, a trait-mediated indirect effect of humans that spatially decouples predators from prey. The purpose of this research was to test the hypothesis that high-human activity was displacing predators and thus indirectly creating spatial refuge for prey species, helping prey win the “space race”. We measured the occurrence of eleven large mammal species (including humans and cattle) at 43 camera traps deployed on roads and trails in southwest Alberta, Canada. We tested species co-occurrence at camera sites using hierarchical cluster and nonmetric multidimensional scaling (NMS) analyses; and tested whether human activity, food and/or habitat influenced predator and prey species counts at camera sites using regression tree analysis. Cluster and NMS analysis indicated that at camera sites humans co-occurred with prey species more than predator species and predator species had relatively low co-occurrence with prey species. Regression tree analysis indicated that prey species were three times more abundant on roads and trails with >32 humans/day. However, predators were less abundant on roads and trails that exceeded 18 humans/day. Our results support the hypothesis that high-human activity displaced predators but not prey species, creating spatial refuge from predation. High-human activity on roads and trails (i.e., >18 humans/day) has the potential to interfere with predator-prey interactions via trait-mediated direct and indirect effects. We urge scientist and managers to carefully consider and quantify

  1. Constructing vulnerabilty and protective measures indices for the enhanced critical infrastructure protection program.

    SciTech Connect

    Fisher, R. E.; Buehring, W. A.; Whitfield, R. G.; Bassett, G. W.; Dickinson, D. C.; Haffenden, R. A.; Klett, M. S.; Lawlor, M. A.; Decision and Information Sciences; LANL

    2009-10-14

    The US Department of Homeland Security (DHS) has directed its Protective Security Advisors (PSAs) to form partnerships with the owners and operators of assets most essential to the Nation's well being - a subclass of critical infrastructure and key resources (CIKR) - and to conduct site visits for these and other high-risk assets as part of the Enhanced Critical Infrastructure Protection (ECIP) Program. During each such visit, the PSA documents information about the facility's current CIKR protection posture and overall security awareness. The primary goals for ECIP site visits (DHS 2009) are to: (1) inform facility owners and operators of the importance of their facilities as an identified high-priority CIKR and the need to be vigilant in light of the ever-present threat of terrorism; (2) identify protective measures currently in place at these facilities, provide comparisons of CIKR protection postures across like assets, and track the implementation of new protective measures; and (3) enhance existing relationships among facility owners and operators; DHS; and various Federal, State, local tribal, and territorial partners. PSAs conduct ECIP visits to assess overall site security; educate facility owners and operators about security; help owners and operators identify gaps and potential improvements; and promote communication and information sharing among facility owners and operators, DHS, State governments, and other security partners. Information collected during ECIP visits is used to develop metrics; conduct sector-by-sector and cross-sector vulnerability comparisons; identify security gaps and trends across CIKR sectors and subsectors; establish sector baseline security survey results; and track progress toward improving CIKR security through activities, programs, outreach, and training (Snyder 2009). The data being collected are used in a framework consistent with the National Infrastructure Protection Plan (NIPP) risk criteria (DHS 2009). The NIPP

  2. The detectability half-life in arthropod predator-prey research: what it is, why we need it, how to measure it, and how to use it.

    PubMed

    Greenstone, Matthew H; Payton, Mark E; Weber, Donald C; Simmons, Alvin M

    2014-08-01

    Molecular gut-content analysis enables detection of arthropod predation with minimal disruption of ecosystem processes. Most assays produce only qualitative results, with each predator testing either positive or negative for target prey remains. Nevertheless, they have yielded important insights into community processes. For example, they have confirmed the long-hypothesized role of generalist predators in retarding early-season build-up of pest populations prior to the arrival of more specialized predators and parasitoids and documented the ubiquity of secondary and intraguild predation. However, raw qualitative gut-content data cannot be used to assess the relative impact of different predator taxa on prey population dynamics: they must first be weighted by the relative detectability periods for molecular prey remains for each predator-prey combination. If this is not carried out, interpretations of predator impact will be biased towards those with the longest detectabilities. We review the challenges in determining detectability half-lives, including unstated assumptions that have often been ignored in the performance of feeding trials. We also show how detectability half-lives can be used to properly weight assay data to rank predators by their importance in prey population suppression, and how sets of half-lives can be used to test hypotheses concerning predator ecology and physiology. We use data from 32 publications, comprising 97 half-lives, to generate and test hypotheses on taxonomic differences in detectability half-lives and discuss the possible role of the detectability half-life in interpreting qPCR and next-generation sequencing data.

  3. Density-dependent effects of prey defenses and predator offenses.

    PubMed

    Jeschke, Jonathan M

    2006-10-21

    Defenses protect prey, while offenses arm predators. Some defenses and offenses are constitutive (e.g. tortoise shells), while others are phenotypically plastic and not always expressed (e.g. neckteeth in water fleas). All of them are costly and only adaptive at certain prey densities. Here, I analyse such density-dependent effects, applying a functional response model to categorize defenses and offenses and qualitatively predict at which prey densities each category should evolve (if it is constitutive) or be expressed (if it is phenotypically plastic). The categories refer to the step of the predation cycle that a defense or offense affects: (1) search, (2) encounter, (3) detection, (4) attack, or (5) meal. For example, prey warning signals such as red coloration prevent predator attacks and are hence step 4 defenses, while sharp predator eyes enhance detection and are step 3 offenses. My theoretical analyses predict that step 1 defenses, which prevent predators from searching for their next meal (e.g. toxic substances), evolve or are expressed at intermediate prey densities. Other defenses, however, should be most beneficial at low prey densities. Regarding predators, step 1 offenses (e.g. immunity against prey toxins) are predicted to evolve or be expressed at high prey densities, other offenses at intermediate densities. I provide evidence from the literature that supports these predictions.

  4. The Allometry of Prey Preferences

    PubMed Central

    Kalinkat, Gregor; Rall, Björn Christian; Vucic-Pestic, Olivera; Brose, Ulrich

    2011-01-01

    The distribution of weak and strong non-linear feeding interactions (i.e., functional responses) across the links of complex food webs is critically important for their stability. While empirical advances have unravelled constraints on single-prey functional responses, their validity in the context of complex food webs where most predators have multiple prey remain uncertain. In this study, we present conceptual evidence for the invalidity of strictly density-dependent consumption as the null model in multi-prey experiments. Instead, we employ two-prey functional responses parameterised with allometric scaling relationships of the functional response parameters that were derived from a previous single-prey functional response study as novel null models. Our experiments included predators of different sizes from two taxonomical groups (wolf spiders and ground beetles) simultaneously preying on one small and one large prey species. We define compliance with the null model predictions (based on two independent single-prey functional responses) as passive preferences or passive switching, and deviations from the null model as active preferences or active switching. Our results indicate active and passive preferences for the larger prey by predators that are at least twice the size of the larger prey. Moreover, our approach revealed that active preferences increased significantly with the predator-prey body-mass ratio. Together with prior allometric scaling relationships of functional response parameters, this preference allometry may allow estimating the distribution of functional response parameters across the myriads of interactions in natural ecosystems. PMID:21998724

  5. Monitoring of the ventilatory status of anesthetized birds of prey by using end-tidal carbon dioxide measured with a microstream capnometer.

    PubMed

    Desmarchelier, Marion; Rondenay, Yves; Fitzgerald, Guy; Lair, Stéphane

    2007-03-01

    The relationship between end-tidal partial pressure of carbon dioxide (PETCO2), arterial partial pressure of carbon dioxide (PaCO2), and blood pH in isoflurane-anesthetized raptors was evaluated. PaCO2 and pH were determined in serial arterial samples from isoflurane anesthetized birds and compared with concurrent end-tidal partial pressure of carbon dioxide measured with a Microstream sidestream capnograph. Forty-eight paired samples, taken from 11 birds of prey (weighing 416-2,062 g), were used to determine correlations coefficients between PaCO2 and PETCO2, and between PETCO2 and pH. Limits of agreement between PaCO2 and PETCO2 also were calculated. Strong correlations were observed between PaCO2 and PETCO2 (r = 0.94; P < 0.0001) as well as between PETCO2 and pH (r = -0.90; P < 0.0001). However, the level of agreement between PaCO2 and PETCO2 varied considerably. Low values of PETCO2, ranging from 18 to 29 mm Hg, exceeded the concomitantly measured values of PaCO2 by an average of 6.0 mm Hg (6.0 +/- 1.9 mm Hg; mean +/- SD). Conversely, high values of PETCO2, ranging from 50 to 63 mm Hg, were on average 7.6 mm Hg (7.6 +/- 9.8 mm Hg) lower than values of PaCO2. In the 30 to 49 mm Hg range for PETCO2, the difference between PETCO2 and PaCO2 was on average 1.0 mm Hg (1.0 +/- 8.5 mm Hg). These results suggest that the capnograph used provided a sufficiently accurate estimation of arterial partial pressure of carbon dioxide for birds weighing > 400 g and receiving manual positive ventilation with a Bain system. In our study, the linear relationship observed between the pH and the end-tidal partial pressure of carbon dioxide suggested that the monitoring of end-tidal partial pressure of carbon dioxide also can be useful to prevent respiratory acidosis. PMID:17469268

  6. Protecting entanglement from correlated amplitude damping channel using weak measurement and quantum measurement reversal

    NASA Astrophysics Data System (ADS)

    Xiao, Xing; Yao, Yao; Xie, Ying-Mao; Wang, Xing-Hua; Li, Yan-Ling

    2016-06-01

    Based on the quantum technique of weak measurement, we propose a scheme to protect the entanglement from correlated amplitude damping decoherence. In contrast to the results of memoryless amplitude damping channel, we show that the memory effects play a significant role in the suppression of entanglement sudden death and protection of entanglement under severe decoherence. Moreover, we find that the initial entanglement could be drastically amplified by the combination of weak measurement and quantum measurement reversal even under the correlated amplitude damping channel. The underlying mechanism can be attributed to the probabilistic nature of weak measurements.

  7. Protecting entanglement from correlated amplitude damping channel using weak measurement and quantum measurement reversal

    NASA Astrophysics Data System (ADS)

    Xiao, Xing; Yao, Yao; Xie, Ying-Mao; Wang, Xing-Hua; Li, Yan-Ling

    2016-09-01

    Based on the quantum technique of weak measurement, we propose a scheme to protect the entanglement from correlated amplitude damping decoherence. In contrast to the results of memoryless amplitude damping channel, we show that the memory effects play a significant role in the suppression of entanglement sudden death and protection of entanglement under severe decoherence. Moreover, we find that the initial entanglement could be drastically amplified by the combination of weak measurement and quantum measurement reversal even under the correlated amplitude damping channel. The underlying mechanism can be attributed to the probabilistic nature of weak measurements.

  8. Do lions Panthera leo actively select prey or do prey preferences simply reflect chance responses via evolutionary adaptations to optimal foraging?

    PubMed

    Hayward, Matt W; Hayward, Gina J; Tambling, Craig J; Kerley, Graham I H

    2011-01-01

    Research on coursing predators has revealed that actions throughout the predatory behavioral sequence (using encounter rate, hunting rate, and kill rate as proxy measures of decisions) drive observed prey preferences. We tested whether similar actions drive the observed prey preferences of a stalking predator, the African lion Panthera leo. We conducted two 96 hour, continuous follows of lions in Addo Elephant National Park seasonally from December 2003 until November 2005 (16 follows), and compared prey encounter rate with prey abundance, hunt rate with prey encounter rate, and kill rate with prey hunt rate for the major prey species in Addo using Jacobs' electivity index. We found that lions encountered preferred prey species far more frequently than expected based on their abundance, and they hunted these species more frequently than expected based on this higher encounter rate. Lions responded variably to non-preferred and avoided prey species throughout the predatory sequence, although they hunted avoided prey far less frequently than expected based on the number of encounters of them. We conclude that actions of lions throughout the predatory behavioural sequence, but particularly early on, drive the prey preferences that have been documented for this species. Once a hunt is initiated, evolutionary adaptations to the predator-prey interactions drive hunting success.

  9. Population and behavioural responses of native prey to alien predation.

    PubMed

    Kovacs, Eszter Krasznai; Crowther, Mathew S; Webb, Jonathan K; Dickman, Christopher R

    2012-04-01

    The introduction of invasive alien predators often has catastrophic effects on populations of naïve native prey, but in situations where prey survive the initial impact a predator may act as a strong selective agent for prey that can discriminate and avoid it. Using two common species of Australian small mammals that have persisted in the presence of an alien predator, the European red fox Vulpes vulpes, for over a century, we hypothesised that populations of both would perform better where the activity of the predator was low than where it was high and that prey individuals would avoid signs of the predator's presence. We found no difference in prey abundance in sites with high and low fox activity, but survival of one species-the bush rat Rattus fuscipes-was almost twofold higher where fox activity was low. Juvenile, but not adult rats, avoided fox odour on traps, as did individuals of the second prey species, the brown antechinus, Antechinus stuartii. Both species also showed reduced activity at foraging trays bearing fox odour in giving-up density (GUD) experiments, although GUDs and avoidance of fox odour declined over time. Young rats avoided fox odour more strongly where fox activity was high than where it was low, but neither adult R. fuscipes nor A. stuartii responded differently to different levels of fox activity. Conservation managers often attempt to eliminate alien predators or to protect predator-naïve prey in protected reserves. Our results suggest that, if predator pressure can be reduced, otherwise susceptible prey may survive the initial impact of an alien predator, and experience selection to discriminate cues to its presence and avoid it over the longer term. Although predator reduction is often feasible, identifying the level of reduction that will conserve prey and allow selection for avoidance remains an important challenge. PMID:22042524

  10. Nuclear fragmentation measurements for hadrontherapy and space radiation protection

    SciTech Connect

    De Napoli, M.; Agodi, C.; Blancato, A. A.; Cavallaro, M.; Cirrone, G. A. P.; Cuttone, G.; Sardina, D.; Scuderi, V.; Battistoni, G.; Bondi, M.; Cappuzzello, F.; Carbone, D.; Nicolosi, D.; Raciti, G.; Tropea, S.; Giacoppo, F.; Morone, M. C.; Pandola, L.; Rapisarda, E.; Romano, F.; and others

    2013-04-19

    Nuclear fragmentation measurements are necessary in hadrontherapy and space radiation protection, to predict the effects of the ion nuclear interactions within the human body. Nowadays, a very limited set of carbon fragmentation cross sections has been measured and in particular, to our knowledge, no double differential fragmentation cross sections at intermediate energies are available in literature. We have measured the double differential cross sections and the angular distributions of the secondary fragments produced in the {sup 12}C fragmentation at 62 AMeV on a thin carbon target. The experimental data have been also used to benchmark the prediction capability of the Geant4 Monte Carlo code at intermediate energies, where it was never tested before.

  11. Tactile experience shapes prey-capture behavior in Etruscan shrews.

    PubMed

    Anjum, Farzana; Brecht, Michael

    2012-01-01

    A crucial role of tactile experience for the maturation of neural response properties in the somatosensory system is well established, but little is known about the role of tactile experience in the development of tactile behaviors. Here we study how tactile experience affects prey capture behavior in Etruscan shrews, Suncus etruscus. Prey capture in adult shrews is a high-speed behavior that relies on precise attacks guided by tactile Gestalt cues. We studied the role of tactile experience by three different approaches. First, we analyzed the hunting skills of young shrews' right after weaning. We found that prey capture in young animals in most, but not all, aspects is similar to that of adults. Second, we performed whisker trimming for 3-4 weeks after birth. Such deprivation resulted in a lasting disruption of prey capture even after whisker re-growth: attacks lacked precise targeting and had a lower success rate. Third, we presented adult shrews with an entirely novel prey species, the giant cockroach. The shape of this roach is very different from the shrew's normal (cricket) prey and the thorax-the preferred point of attack in crickets-is protected by a heavy cuticle. Initially shrews attacked giant roaches the same way they attack crickets and targeted the thoracic region. With progressive experience, however, shrews adopted a new attack strategy targeting legs and underside of the roaches while avoiding other body parts. Speed and efficiency of attacks improved. These data suggest that tactile experience shapes prey capture behavior. PMID:22701408

  12. Experimental determination of the spatial scale of a prey patch from the predator's perspective.

    PubMed

    Birk, Matthew A; White, J Wilson

    2014-03-01

    Foraging theory predicts that predators should prefer foraging in habitat patches with higher prey densities. However, density depends on the spatial scale at which a "patch" is defined by an observer. Ecologists strive to measure prey densities at the same scale that predators do, but many natural landscapes lack obvious, well-defined prey patches. Thus one must determine the scale at which predators define patches of prey. We estimated the scale at which guppies, Poecilia reticulata, selected patches of zooplankton prey using a behavioral assay. Guppies could choose between two prey arrays, each manipulated to have a density that depended on the spatial scale at which density was calculated. We estimated the scale of guppy foraging by comparing guppy preferences across a series of trials in which we systematically varied the scale associated with "high" prey density. This approach enables the application of foraging theory to non-discrete habitats and prey landscapes. PMID:24241641

  13. Goshawk prey have more bacteria than non-prey.

    PubMed

    Møller, A P; Peralta-Sánchez, J M; Nielsen, J T; López-Hernández, E; Soler, J J

    2012-03-01

    1. Predators often prey on individuals that are sick or otherwise weakened. Although previous studies have shown higher abundance of parasites in prey, whether prey have elevated loads of micro-organisms remains to be determined. 2. We quantified the abundance of bacteria and fungi on feathers of woodpigeons Columba palumbus L., jays Garrulus glandarius L. and blackbirds Turdus merula L. that either fell prey to goshawks Accipiter gentilis L. or were not depredated. 3. We found an almost three-fold increase in bacterial load of prey compared with non-prey, while there was no significant difference between prey and non-prey in level of fungal infection of the plumage. 4. The results were not confounded by differences in size or mass of feathers, date of collection of feathers, or date of analysis of feathers for micro-organisms. 5. These findings suggest a previously unknown contribution of bacteria to risk of predation, with important implications for behaviour, population ecology and community ecology. PMID:22039986

  14. Acoustic shadows help gleaning bats find prey, but may be defeated by prey acoustic camouflage on rough surfaces.

    PubMed

    Clare, Elizabeth L; Holderied, Marc W

    2015-01-01

    Perceptual abilities of animals, like echolocating bats, are difficult to study because they challenge our understanding of non-visual senses. We used novel acoustic tomography to convert echoes into visual representations and compare these cues to traditional echo measurements. We provide a new hypothesis for the echo-acoustic basis of prey detection on surfaces. We propose that bats perceive a change in depth profile and an 'acoustic shadow' cast by prey. The shadow is more salient than prey echoes and particularly strong on smooth surfaces. This may explain why bats look for prey on flat surfaces like leaves using scanning behaviour. We propose that rather than forming search images for prey, whose characteristics are unpredictable, predators may look for disruptions to the resting surface (acoustic shadows). The fact that the acoustic shadow is much fainter on rougher resting surfaces provides the first empirical evidence for 'acoustic camouflage' as an anti-predator defence mechanism. PMID:26327624

  15. Ecoepidemic predator-prey model with feeding satiation, prey herd behavior and abandoned infected prey.

    PubMed

    Kooi, Bob W; Venturino, Ezio

    2016-04-01

    In this paper we analyse a predator-prey model where the prey population shows group defense and the prey individuals are affected by a transmissible disease. The resulting model is of the Rosenzweig-MacArthur predator-prey type with an SI (susceptible-infected) disease in the prey. Modeling prey group defense leads to a square root dependence in the Holling type II functional for the predator-prey interaction term. The system dynamics is investigated using simulations, classical existence and asymptotic stability analysis and numerical bifurcation analysis. A number of bifurcations, such as transcritical and Hopf bifurcations which occur commonly in predator-prey systems will be found. Because of the square root interaction term there is non-uniqueness of the solution and a singularity where the prey population goes extinct in a finite time. This results in a collapse initiated by extinction of the healthy or susceptible prey and thereafter the other population(s). When also a positive attractor exists this leads to bistability similar to what is found in predator-prey models with a strong Allee effect. For the two-dimensional disease-free (i.e. the purely demographic) system the region in the parameter space where bistability occurs is marked by a global bifurcation. At this bifurcation a heteroclinic connection exists between saddle prey-only equilibrium points where a stable limit cycle together with its basin of attraction, are destructed. In a companion paper (Gimmelli et al., 2015) the same model was formulated and analysed in which the disease was not in the prey but in the predator. There we also observed this phenomenon. Here we extend its analysis using a phase portrait analysis. For the three-dimensional ecoepidemic predator-prey system where the prey is affected by the disease, also tangent bifurcations including a cusp bifurcation and a torus bifurcation of limit cycles occur. This leads to new complex dynamics. Continuation by varying one parameter

  16. Implementing planetary protection measures on the Mars Science Laboratory.

    PubMed

    Benardini, James N; La Duc, Myron T; Beaudet, Robert A; Koukol, Robert

    2014-01-01

    The Mars Science Laboratory (MSL), comprising a cruise stage; an aeroshell; an entry, descent, and landing system; and the radioisotope thermoelectric generator-powered Curiosity rover, made history with its unprecedented sky crane landing on Mars on August 6, 2012. The mission's primary science objective has been to explore the area surrounding Gale Crater and assess its habitability for past life. Because microbial contamination could profoundly impact the integrity of the mission and compliance with international treaty was required, planetary protection measures were implemented on MSL hardware to verify that bioburden levels complied with NASA regulations. By applying the proper antimicrobial countermeasures throughout all phases of assembly, the total bacterial endospore burden of MSL at the time of launch was kept to 2.78×10⁵ spores, well within the required specification of less than 5.0×10⁵ spores. The total spore burden of the exposed surfaces of the landed MSL hardware was 5.64×10⁴, well below the allowed limit of 3.0×10⁵ spores. At the time of launch, the MSL spacecraft was burdened with an average of 22 spores/m², which included both planned landed and planned impacted hardware. Here, we report the results of a campaign to implement and verify planetary protection measures on the MSL flight system.

  17. Implementing planetary protection measures on the Mars Science Laboratory.

    PubMed

    Benardini, James N; La Duc, Myron T; Beaudet, Robert A; Koukol, Robert

    2014-01-01

    The Mars Science Laboratory (MSL), comprising a cruise stage; an aeroshell; an entry, descent, and landing system; and the radioisotope thermoelectric generator-powered Curiosity rover, made history with its unprecedented sky crane landing on Mars on August 6, 2012. The mission's primary science objective has been to explore the area surrounding Gale Crater and assess its habitability for past life. Because microbial contamination could profoundly impact the integrity of the mission and compliance with international treaty was required, planetary protection measures were implemented on MSL hardware to verify that bioburden levels complied with NASA regulations. By applying the proper antimicrobial countermeasures throughout all phases of assembly, the total bacterial endospore burden of MSL at the time of launch was kept to 2.78×10⁵ spores, well within the required specification of less than 5.0×10⁵ spores. The total spore burden of the exposed surfaces of the landed MSL hardware was 5.64×10⁴, well below the allowed limit of 3.0×10⁵ spores. At the time of launch, the MSL spacecraft was burdened with an average of 22 spores/m², which included both planned landed and planned impacted hardware. Here, we report the results of a campaign to implement and verify planetary protection measures on the MSL flight system. PMID:24432776

  18. Birds of Prey of Wisconsin.

    ERIC Educational Resources Information Center

    Hamerstrom, Frances

    This copiously illustrated document is designed to be a field quide to birds of prey that are common to Wisconsin, as well as to some that enter the state occasionally. An introduction discusses birds of prey with regard to migration patterns, the relationship between common names and the attitudes of people toward certain birds, and natural signs…

  19. Predatory Bacteriovorax Communities Ordered by Various Prey Species

    PubMed Central

    Chen, Huan; Young, Shanterial; Berhane, Timkhite-Kulu; Williams, Henry N.

    2012-01-01

    The role of predation in altering microbial communities has been studied for decades but few examples are known for bacterial predators. Bacteriovorax are halophilic prokaryotes that prey on susceptible Gram-negative bacteria. We recently reported novel observations on the differential selection of Bacteriovorax phylotypes by two different prey, Vibrio parahaemolyticus and Vibrio vulnificus. However, the conclusion is restricted by the limited number of prey tested. In this study, we have conducted two independent investigations involving eight species of prey bacteria while using V. vulnificus and V. parahaemolytics as reference strains. Water samples collected from Dry Bar, Apalachicola Bay were used to establish microcosms which were respectively spiked with prey strains Vibrio cholerae, Escherichia coli or Pseudomonas putida to examine the response of native Bacteriovorax to freshwater bacteria. Indigenous Vibrio sp., Pseudoalteromonas sp., Photobacterium sp. and a clinical strain of V. vulnificus were also tested for the impact of saltwater prey on the Bacteriovorax community. At 24 hour intervals, optical density of the microcosm samples and the abundance of Bacteriovorax were measured over five days. The predominant Bacteriovorax plaques were selected and analyzed by 16S rRNA gene amplification and sequencing. In addition, the impacts of prey on predator population and bacterial community composition were investigated using culture independent denaturing gradient gel electrophoresis. Strikingly, Cluster IV was found consistently as the predominant phylotype produced by the freshwater prey. For all saltwater prey, subgroups of Bacteriovorax phylotype IX were the major predators recovered. The results suggest that prey is an important factor along with temperature, salinity and other environmental parameters in shaping Bacteriovorax communities in aquatic systems. PMID:22461907

  20. Predator-prey interactions mediated by prey personality and predator hunting mode.

    PubMed

    Belgrad, Benjamin A; Griffen, Blaine D

    2016-04-13

    Predator-prey interactions are important drivers in structuring ecological communities. However, despite widespread acknowledgement that individual behaviours and predator species regulate ecological processes, studies have yet to incorporate individual behavioural variations in a multipredator system. We quantified a prevalent predator avoidance behaviour to examine the simultaneous roles of prey personality and predator hunting mode in governing predator-prey interactions. Mud crabs, Panopeus herbstii, reduce their activity levels and increase their refuge use in the presence of predator cues. We measured mud crab mortality and consistent individual variations in the strength of this predator avoidance behaviour in the presence of predatory blue crabs, Callinectes sapidus, and toadfish, Opsanus tau We found that prey personality and predator species significantly interacted to affect mortality with blue crabs primarily consuming bold mud crabs and toadfish preferentially selecting shy crabs. Additionally, the strength of the predator avoidance behaviour depended upon the predation risk from the predator species. Consequently, the personality composition of populations and predator hunting mode may be valuable predictors of both direct and indirect predator-prey interaction strength. These findings support theories postulating mechanisms for maintaining intraspecies diversity and have broad implications for community dynamics.

  1. Predator-prey interactions mediated by prey personality and predator hunting mode.

    PubMed

    Belgrad, Benjamin A; Griffen, Blaine D

    2016-04-13

    Predator-prey interactions are important drivers in structuring ecological communities. However, despite widespread acknowledgement that individual behaviours and predator species regulate ecological processes, studies have yet to incorporate individual behavioural variations in a multipredator system. We quantified a prevalent predator avoidance behaviour to examine the simultaneous roles of prey personality and predator hunting mode in governing predator-prey interactions. Mud crabs, Panopeus herbstii, reduce their activity levels and increase their refuge use in the presence of predator cues. We measured mud crab mortality and consistent individual variations in the strength of this predator avoidance behaviour in the presence of predatory blue crabs, Callinectes sapidus, and toadfish, Opsanus tau We found that prey personality and predator species significantly interacted to affect mortality with blue crabs primarily consuming bold mud crabs and toadfish preferentially selecting shy crabs. Additionally, the strength of the predator avoidance behaviour depended upon the predation risk from the predator species. Consequently, the personality composition of populations and predator hunting mode may be valuable predictors of both direct and indirect predator-prey interaction strength. These findings support theories postulating mechanisms for maintaining intraspecies diversity and have broad implications for community dynamics. PMID:27075257

  2. Prey morphology constrains the feeding ecology of an aquatic generalist predator.

    PubMed

    Willson, John D; Hopkins, William A

    2011-03-01

    Resource availability and accessibility are primary factors guiding the distribution and abundance of organisms. For generalists, prey availability reflects both prey abundance and differences in quality among prey taxa. Although some aspects of prey quality, such as nutritional composition, are well studied, our understanding of how prey morphology contributes to overall prey quality is limited. Because snakes cannot reduce prey size by mastication, many aspects of their feeding ecology (e.g., maximum prey size, feeding performance, and the degree of postprandial locomotor impairment) may be affected by prey shape. We conducted a uniquely comprehensive comparison of prey quality for a generalist species, the banded watersnake (Nerodia fasciata), using prey that were similar in mass and presumably similar in nutritional composition but different in shape and habitat association. Specifically, we compared nutritional composition and shape of paedomorphic salamanders (Ambystoma talpoideum) and sunfish (Lepomis MARGINATUS) and used a series of repeated-measures experiments to examine feeding performance (number of prey consumed, maximum prey size, and intra-oral transport time), digestive metabolism (specific dynamic action, SDA), and postprandial locomotor performance of snakes fed Ambystoma and Lepomis. Cost of digestion was similar between the prey types, likely reflecting their similar nutritional composition. However, snakes consumed larger Ambystoma than Lepomis and intra-oral transport time was much shorter for Ambystoma. Snakes fed Lepomis also suffered greater reduction in crawling speed than those fed Ambystoma. These differences highlight the need for behaviorally integrated approaches to understanding prey quality and support field observations of the importance of amphibian prey for juvenile watersnakes.

  3. Acoustic mirror effect increases prey detection distance in trawling bats

    NASA Astrophysics Data System (ADS)

    Siemers, Björn M.; Baur, Eric; Schnitzler, Hans-Ulrich

    2005-06-01

    Many different and phylogenetically distant species of bats forage for insects above water bodies and take insects from and close to the surface; the so-called ‘trawling behaviour’. Detection of surface-based prey by echolocation is facilitated by acoustically smooth backgrounds such as water surfaces that reflect sound impinging at an acute angle away from the bat and thereby render a prey object acoustically conspicuous. Previous measurements had shown that the echo amplitude of a target on a smooth surface is higher than that of the same target in mid-air, due to an acoustic mirror effect. In behavioural experiments with three pond bats (Myotis dasycneme), we tested the hypothesis that the maximum distances at which bats can detect prey are larger for prey on smooth surfaces than for the same prey in an airborne situation. We determined the moment of prey detection from a change in echolocation behaviour and measured the detection distance in 3D space from IR-video recordings using stereo-photogrammetry. The bats showed the predicted increase in detection distance for prey on smooth surfaces. The acoustic mirror effect therefore increases search efficiency and contributes to the acoustic advantages encountered by echolocating bats when foraging at low heights above smooth water surfaces. These acoustic advantages may have favoured the repeated evolution of trawling behaviour.

  4. The effect of structural complexity, prey density, and "predator-free space" on prey survivorship at created oyster reef mesocosms

    USGS Publications Warehouse

    Humphries, Austin T.; La Peyre, Megan K.; Decossas, Gary A.

    2011-01-01

    Interactions between predators and their prey are influenced by the habitat they occupy. Using created oyster (Crassostrea virginica) reef mesocosms, we conducted a series of laboratory experiments that created structure and manipulated complexity as well as prey density and “predator-free space” to examine the relationship between structural complexity and prey survivorship. Specifically, volume and spatial arrangement of oysters as well as prey density were manipulated, and the survivorship of prey (grass shrimp, Palaemonetes pugio) in the presence of a predator (wild red drum, Sciaenops ocellatus) was quantified. We found that the presence of structure increased prey survivorship, and that increasing complexity of this structure further increased survivorship, but only to a point. This agrees with the theory that structural complexity may influence predator-prey dynamics, but that a threshold exists with diminishing returns. These results held true even when prey density was scaled to structural complexity, or the amount of “predator-free space” was manipulated within our created reef mesocosms. The presence of structure and its complexity (oyster shell volume) were more important in facilitating prey survivorship than perceived refugia or density-dependent prey effects. A more accurate indicator of refugia might require “predator-free space” measures that also account for the available area within the structure itself (i.e., volume) and not just on the surface of a structure. Creating experiments that better mimic natural conditions and test a wider range of “predator-free space” are suggested to better understand the role of structural complexity in oyster reefs and other complex habitats.

  5. The effect of structural complexity, prey density, and "predator-free space" on prey survivorship at created oyster reef mesocosms.

    PubMed

    Humphries, Austin T; La Peyre, Megan K; Decossas, Gary A

    2011-01-01

    Interactions between predators and their prey are influenced by the habitat they occupy. Using created oyster (Crassostrea virginica) reef mesocosms, we conducted a series of laboratory experiments that created structure and manipulated complexity as well as prey density and "predator-free space" to examine the relationship between structural complexity and prey survivorship. Specifically, volume and spatial arrangement of oysters as well as prey density were manipulated, and the survivorship of prey (grass shrimp, Palaemonetes pugio) in the presence of a predator (wild red drum, Sciaenops ocellatus) was quantified. We found that the presence of structure increased prey survivorship, and that increasing complexity of this structure further increased survivorship, but only to a point. This agrees with the theory that structural complexity may influence predator-prey dynamics, but that a threshold exists with diminishing returns. These results held true even when prey density was scaled to structural complexity, or the amount of "predator-free space" was manipulated within our created reef mesocosms. The presence of structure and its complexity (oyster shell volume) were more important in facilitating prey survivorship than perceived refugia or density-dependent prey effects. A more accurate indicator of refugia might require "predator-free space" measures that also account for the available area within the structure itself (i.e., volume) and not just on the surface of a structure. Creating experiments that better mimic natural conditions and test a wider range of "predator-free space" are suggested to better understand the role of structural complexity in oyster reefs and other complex habitats. PMID:22145037

  6. [Personal protection measures against blood-sucking insects and ticks].

    PubMed

    Orshan, Laor; Wilamowski, Amos; Pener, Hedva

    2010-09-01

    Blood-sucking arthropods are major vectors of various pathogens like viruses, bacteria, protozoa and nematodes. Preventing exposure to the vector is imperative especially when vaccine and prophylactic treatments are not available. Personal protection measures (PPM) are essential and often the only means available when dealing with blood-sucking disease transmitting arthropods. Awareness of the risk in the specific areas of travel is the first step to be taken before and while traveling. PPM include preventive personal behavior, suitable clothing, application of insect repellents to the skin, the use of space repellents, impregnation of clothing, camping gear and bed nets and, when necessary, ground spraying of insecticides. The registered and recommended active ingredients for skin application are Deet, picaridin (icaridin), p-menthane-3,8-diol (PMD) and IR3535. Volatile pyrethrins are used as space repellents while pyrethroids, especially permethrin, are employed for impregnation and for ground spraying. It is recommended to purchase only products registered in Israel or other developed countries. These products should have a detailed label specifying the concentration of the active ingredient, application instructions and the duration of protection.

  7. Effect of bank protection measures, Stehekin River, Chelan County, Washington

    USGS Publications Warehouse

    Nelson, L.M.

    1986-01-01

    An investigation of the lower Stehekin River was conducted to study the effects on flood elevations and velocities from four bank protection and flood prevention measures that are being contemplated as a means of reducing erosional losses of river bank property. These measures are: bank armoring, armored revetment levees, spur dikes, and redevelopment of old cutoff channels. The banks at seven study sites could be armored without adverse effect on the flood velocities and elevations. The largest increases due to armoring--up to 1.6 ft/sec in velocity and 1 ft in elevation--occurred in the vicinity of sites 5, 6, and 7 where the gradient of the river channel is about 50 ft/mi and the velocities are high to begin with (about 6 to 13 ft/sec). The use of a levee in conjunction with armoring on the northeast bank from sites 5 to 7 would increase the velocities as much as 2.8 ft/sec and increase the elevation as much as 1 ft, but it would also provide some flood protection to the east bank, which is frequently inundated. Spur dikes were considered a practical alternative only at site 3, where reduced bank erosion may occur without aggravating flood inundation or erosion elsewhere. The rerouting of flood flow through an old cutoff channel near site 1 increased the velocity by 3.2 ft/sec and the elevation by 1 ft for the 100-year flood; however, it would move floodwater away from residential property where bank erosion is a problem. The few other old channels that shortcut river bends where much erosion occurs are apparently already part of the channel during floods. (Author 's abstract)

  8. Dynamics of prey prehension by chameleons through viscous adhesion

    NASA Astrophysics Data System (ADS)

    Brau, Fabian; Lanterbecq, Déborah; Zghikh, Leïla-Nastasia; Bels, Vincent; Damman, Pascal

    2016-10-01

    Among predators using an adhesive tongue to feed, chameleons are able to capture large prey by projecting the tongue at high acceleration. Once in contact with a prey, the tongue retracts with a comparable acceleration to bring it to the mouth. A strong adhesion between the tongue tip and the prey is therefore required during the retraction phase to ensure a successful capture. To investigate the mechanism responsible for this strong bond, the viscosity of the mucus produced at the chameleon's tongue pad is measured, using the viscous drag exerted on rolling beads by a thin layer of mucus. Here we show that the viscosity of this secretion is about 400 times larger than that of human saliva. We incorporate this viscosity into a dynamical model for viscous adhesion, which describes the motion of the compliant tongue and the prey during the retraction phase. The variation of the maximum prey size with respect to the chameleon body length is derived, and compared with in vivo observations for various chameleon species. Our study shows that the size of the captured prey is not limited by viscous adhesion, owing to the high mucus viscosity and large contact area between the prey and the tongue.

  9. Prey-predator model with a nonlocal consumption of prey.

    PubMed

    Banerjee, M; Volpert, V

    2016-08-01

    The prey-predator model with nonlocal consumption of prey introduced in this work extends previous studies of local reaction-diffusion models. Linear stability analysis of the homogeneous in space stationary solution and numerical simulations of nonhomogeneous solutions allow us to analyze bifurcations and dynamics of stationary solutions and of travelling waves. These solutions present some new properties in comparison with the local models. They correspond to different feeding strategies of predators observed in ecology. PMID:27586616

  10. Prey-predator model with a nonlocal consumption of prey

    NASA Astrophysics Data System (ADS)

    Banerjee, M.; Volpert, V.

    2016-08-01

    The prey-predator model with nonlocal consumption of prey introduced in this work extends previous studies of local reaction-diffusion models. Linear stability analysis of the homogeneous in space stationary solution and numerical simulations of nonhomogeneous solutions allow us to analyze bifurcations and dynamics of stationary solutions and of travelling waves. These solutions present some new properties in comparison with the local models. They correspond to different feeding strategies of predators observed in ecology.

  11. Prey-predator model with a nonlocal consumption of prey.

    PubMed

    Banerjee, M; Volpert, V

    2016-08-01

    The prey-predator model with nonlocal consumption of prey introduced in this work extends previous studies of local reaction-diffusion models. Linear stability analysis of the homogeneous in space stationary solution and numerical simulations of nonhomogeneous solutions allow us to analyze bifurcations and dynamics of stationary solutions and of travelling waves. These solutions present some new properties in comparison with the local models. They correspond to different feeding strategies of predators observed in ecology.

  12. Predator size, prey size and threshold food densities of diving ducks: does a common prey base support fewer large animals?

    PubMed

    Richman, Samantha E; Lovvorn, James R

    2009-09-01

    1. Allometry predicts that a given habitat area or common prey biomass supports fewer numbers of larger than smaller predators; however, birds from related taxa or the same feeding guild often deviate from this pattern. In particular, foraging costs of birds may differ among locomotor modes, while intake rates vary with accessibility, handling times and energy content of different-sized prey. Such mechanisms might affect threshold prey densities needed for energy balance, and thus relative numbers of different-sized predators in habitats with varying prey patches. 2. We compared the foraging profitability (energy gain minus cost) of two diving ducks: smaller lesser scaup (Aythya affinis, 450-1090 g) and larger white-winged scoters (Melanitta fusca, 950-1800 g). Calculations were based on past measurements of dive costs with respirometry, and of intake rates of a common bivalve prey ranging in size, energy content and burial depth in sediments. 3. For scaup feeding on small prey <12 mm long, all clams buried deeper than 5 cm were unprofitable at realistic prey densities. For clams buried in the top 5 cm, the profitability threshold decreased from 216 to 34 clams m(-2) as energy content increased from 50 to 300 J clam(-1). 4. For larger scoters feeding on larger prey 18-24 mm long, foraging was profitable for clams buried deeper than 5 cm, with a threshold density of 147 m(-2) for clams containing 380 J clam(-1). For clams <5 cm deep, the threshold density decreased from 86 to 36 clams m(-2) as energy content increased from 380 to 850 J clam(-1). If scoters decreased dive costs by swimming with wings as well as feet (not an option for scaup), threshold prey densities were 11-12% lower. 5. Our results show that threshold densities of total prey numbers for different-sized ducks depend on prey size structure and depth in the sediments. Thus, heterogeneity in disturbance regimes and prey population dynamics can create a mosaic of patches favouring large or small

  13. Preference and Prey Switching in a Generalist Predator Attacking Local and Invasive Alien Pests

    PubMed Central

    Jaworski, Coline C.; Bompard, Anaïs; Genies, Laure; Amiens-Desneux, Edwige; Desneux, Nicolas

    2013-01-01

    Invasive pest species may strongly affect biotic interactions in agro-ecosystems. The ability of generalist predators to prey on new invasive pests may result in drastic changes in the population dynamics of local pest species owing to predator-mediated indirect interactions among prey. On a short time scale, the nature and strength of such indirect interactions depend largely on preferences between prey and on predator behavior patterns. Under laboratory conditions we evaluated the prey preference of the generalist predator Macrolophus pygmaeus Rambur (Heteroptera: Miridae) when it encounters simultaneously the local tomato pest Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) and the invasive alien pest Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae). We tested various ratios of local vs. alien prey numbers, measuring switching by the predator from one prey to the other, and assessing what conditions (e.g. prey species abundance and prey development stage) may favor such prey switching. The total predation activity of M. pygmaeus was affected by the presence of T. absoluta in the prey complex with an opposite effect when comparing adult and juvenile predators. The predator showed similar preference toward T. absoluta eggs and B. tabaci nymphs, but T. absoluta larvae were clearly less attacked. However, prey preference strongly depended on prey relative abundance with a disproportionately high predation on the most abundant prey and disproportionately low predation on the rarest prey. Together with the findings of a recent companion study (Bompard et al. 2013, Population Ecology), the insight obtained on M. pygmaeus prey switching may be useful for Integrated Pest Management in tomato crops, notably for optimal simultaneous management of B. tabaci and T. absoluta, which very frequently co-occur on tomato. PMID:24312646

  14. Understanding spatial distributions: negative density-dependence in prey causes predators to trade-off prey quantity with quality.

    PubMed

    Bijleveld, Allert I; MacCurdy, Robert B; Chan, Ying-Chi; Penning, Emma; Gabrielson, Rich M; Cluderay, John; Spaulding, Eric L; Dekinga, Anne; Holthuijsen, Sander; ten Horn, Job; Brugge, Maarten; van Gils, Jan A; Winkler, David W; Piersma, Theunis

    2016-04-13

    Negative density-dependence is generally studied within a single trophic level, thereby neglecting its effect on higher trophic levels. The 'functional response' couples a predator's intake rate to prey density. Most widespread is a type II functional response, where intake rate increases asymptotically with prey density; this predicts the highest predator densities at the highest prey densities. In one of the most stringent tests of this generality to date, we measured density and quality of bivalve prey (edible cockles Cerastoderma edule) across 50 km² of mudflat, and simultaneously, with a novel time-of-arrival methodology, tracked their avian predators (red knots Calidris canutus). Because of negative density-dependence in the individual quality of cockles, the predicted energy intake rates of red knots declined at high prey densities (a type IV, rather than a type II functional response). Resource-selection modelling revealed that red knots indeed selected areas of intermediate cockle densities where energy intake rates were maximized given their phenotype-specific digestive constraints (as indicated by gizzard mass). Because negative density-dependence is common, we question the current consensus and suggest that predators commonly maximize their energy intake rates at intermediate prey densities. Prey density alone may thus poorly predict intake rates, carrying capacity and spatial distributions of predators. PMID:27053747

  15. Understanding spatial distributions: negative density-dependence in prey causes predators to trade-off prey quantity with quality.

    PubMed

    Bijleveld, Allert I; MacCurdy, Robert B; Chan, Ying-Chi; Penning, Emma; Gabrielson, Rich M; Cluderay, John; Spaulding, Eric L; Dekinga, Anne; Holthuijsen, Sander; ten Horn, Job; Brugge, Maarten; van Gils, Jan A; Winkler, David W; Piersma, Theunis

    2016-04-13

    Negative density-dependence is generally studied within a single trophic level, thereby neglecting its effect on higher trophic levels. The 'functional response' couples a predator's intake rate to prey density. Most widespread is a type II functional response, where intake rate increases asymptotically with prey density; this predicts the highest predator densities at the highest prey densities. In one of the most stringent tests of this generality to date, we measured density and quality of bivalve prey (edible cockles Cerastoderma edule) across 50 km² of mudflat, and simultaneously, with a novel time-of-arrival methodology, tracked their avian predators (red knots Calidris canutus). Because of negative density-dependence in the individual quality of cockles, the predicted energy intake rates of red knots declined at high prey densities (a type IV, rather than a type II functional response). Resource-selection modelling revealed that red knots indeed selected areas of intermediate cockle densities where energy intake rates were maximized given their phenotype-specific digestive constraints (as indicated by gizzard mass). Because negative density-dependence is common, we question the current consensus and suggest that predators commonly maximize their energy intake rates at intermediate prey densities. Prey density alone may thus poorly predict intake rates, carrying capacity and spatial distributions of predators.

  16. Restricting Prey Dispersal Can Overestimate the Importance of Predation in Trophic Cascades

    PubMed Central

    Geraldi, Nathan R.; Macreadie, Peter I.

    2013-01-01

    Predators can affect prey populations and, via trophic cascades, predators can indirectly impact resource populations (2 trophic levels below the predator) through consumption of prey (density-mediated indirect effects; DMIEs) and by inducing predator-avoidance behavior in prey (trait-mediated indirect effects; TMIEs). Prey often employ multiple predator-avoidance behaviors, such as dispersal or reduced foraging activity, but estimates of TMIEs are usually on individual behaviors. We assessed direct and indirect predator effects in a mesocosm experiment using a marine food chain consisting of a predator (toadfish – Opsanus tau), prey (mud crab - Panopeus herbstii) and resource (ribbed mussel – Geukensia demissa). We measured dispersal and foraging activity of prey separately by manipulating both the presence and absence of the predator, and whether prey could or could not disperse into a predator-free area. Consumption of prey was 9 times greater when prey could not disperse, probably because mesocosm boundaries increased predator capture success. Although predator presence did not significantly affect the number of crabs that emigrated, the presence of a predator decreased resource consumption by prey, which resulted in fewer resources consumed for each prey that emigrated in the presence of a predator, and reduced the overall TMIE. When prey were unable to disperse, TMIEs on mussel survival were 3 times higher than the DMIEs. When prey were allowed to disperse, the TMIEs on resource survival increased to 11-times the DMIEs. We found that restricting the ability of prey to disperse, or focusing on only one predator-avoidance behavior, may be underestimating TMIEs. Our results indicate that the relative contribution of behavior and consumption in food chain dynamics will depend on which predator-avoidance behaviors are allowed to occur and measured. PMID:23408957

  17. Measuring the Impact of Child Protection through Activation States

    ERIC Educational Resources Information Center

    Brackenridge, Celia H.; Pawlaczek, Zofia; Bringer, Joy D.; Cockburn, Claudi; Nutt, Gareth; Pitchford, Andy; Russell, Kate

    2005-01-01

    Child protection (CP) has risen to the top of the UK sports policy agenda in the past four years and the Football Association has invested in this major strategy as part of its commitment to "use the power of football to build a better future" (Football Association, 2000a). Evidencing the impact of child protection is, however, a complex task,…

  18. Factors mediating co-occurrence of an economically valuable introduced fish and its native frog prey.

    PubMed

    Hartman, Rosemary; Pope, Karen; Lawler, Sharon

    2014-06-01

    Habitat characteristics mediate predator-prey coexistence in many ecological systems but are seldom considered in species introductions. When economically important introduced predators are stocked despite known negative impacts on native species, understanding the role of refuges, landscape configurations, and community interactions can inform habitat management plans. We measured these factors in basins with introduced trout (Salmonidae) and the Cascades frog (Rana cascadae) to determine, which are responsible for observed patterns of co-occurrence of this economically important predator and its native prey. Large, vegetated shallows were strongly correlated to co-occurrence, and R. cascadae larvae occur in shallower water when fish are present, presumably to escape predation. The number of nearby breeding sites of R. cascadae was also correlated to co-occurrence, but only when the western toad (Anaxyrus boreas) was present. Because A. boreas larvae are unpalatable to fish and resemble R. cascadae, they may provide protection from trout via Batesian mimicry. Although rescue-effect dispersal from nearby populations may maintain co-occurrence, within-lake factors proved more important for predicting co-occurrence. Learning which factors allow co-occurrence between economically important introduced species and their native prey enables managers to make better-informed stocking decisions. PMID:24372671

  19. Factors mediating co-occurrence of an economically valuable introduced fish and its native frog prey.

    PubMed

    Hartman, Rosemary; Pope, Karen; Lawler, Sharon

    2014-06-01

    Habitat characteristics mediate predator-prey coexistence in many ecological systems but are seldom considered in species introductions. When economically important introduced predators are stocked despite known negative impacts on native species, understanding the role of refuges, landscape configurations, and community interactions can inform habitat management plans. We measured these factors in basins with introduced trout (Salmonidae) and the Cascades frog (Rana cascadae) to determine, which are responsible for observed patterns of co-occurrence of this economically important predator and its native prey. Large, vegetated shallows were strongly correlated to co-occurrence, and R. cascadae larvae occur in shallower water when fish are present, presumably to escape predation. The number of nearby breeding sites of R. cascadae was also correlated to co-occurrence, but only when the western toad (Anaxyrus boreas) was present. Because A. boreas larvae are unpalatable to fish and resemble R. cascadae, they may provide protection from trout via Batesian mimicry. Although rescue-effect dispersal from nearby populations may maintain co-occurrence, within-lake factors proved more important for predicting co-occurrence. Learning which factors allow co-occurrence between economically important introduced species and their native prey enables managers to make better-informed stocking decisions.

  20. Relating wolf scat content to prey consumed

    USGS Publications Warehouse

    Floyd, T.J.; Mech, L.D.; Jordan, P.A.

    1978-01-01

    In 9 trials, captive wolves (Canis lupus) were fed prey varying in size from snowshoe hares (Lepus americanus) to adult deer (Odocoileus virginianus), and the resulting scats were counted. Field-collectible scats were distinguished from liquid, noncollectible stools. I n collectible scats, the remains of small prey occurred in greater proportion relative to the prey's weight, and in lesser proportion relative to the prey's numbers, than did the remains of larger prey. A regression equation with an excellent, fit to the data (r2 = 0.97) was derived to estimate the weight of prey eaten per collectible scat for any prey. With this information and average prey weights, the relative numbers of different prey eaten also can be calculated.

  1. Foraging and vulnerability traits modify predator-prey body mass allometry: freshwater macroinvertebrates as a case study.

    PubMed

    Klecka, Jan; Boukal, David S

    2013-09-01

    1. Predation is often size selective, but the role of other traits of the prey and predators in their interactions is little known. This hinders our understanding of the causal links between trophic interactions and the structure of animal communities. Better knowledge of trophic traits underlying predator-prey interactions is also needed to improve models attempting to predict food web structure and dynamics from known species traits. 2. We carried out laboratory experiments with common freshwater macroinvertebrate predators (diving beetles, dragonfly and damselfly larvae and water bugs) and their prey to assess how body size and traits related to foraging (microhabitat use, feeding mode and foraging mode) and to prey vulnerability (microhabitat use, activity and escape behaviour) affect predation strength. 3. The underlying predator-prey body mass allometry characterizing mean prey size and total predation pressure was modified by feeding mode of the predators (suctorial or chewing). Suctorial predators fed upon larger prey and had ˜3 times higher mass-specific predation rate than chewing predators of the same size and may thus have stronger effect on prey abundance. 4. Strength of individual trophic links, measured as mortality of the focal prey caused by the focal predator, was determined jointly by the predator and prey body mass and their foraging and vulnerability traits. In addition to the feeding mode, interactions between prey escape behaviour (slow or fast), prey activity (sedentary or active) and predator foraging mode (searching or ambush) strongly affected prey mortality. Searching predators was ineffective in capturing fast-escape prey in comparison with the remaining predator-prey combinations, while ambush predators caused higher mortality than searching predators and the difference was larger in active prey. 5. Our results imply that the inclusion of the commonly available qualitative data on foraging traits of predators and vulnerability traits

  2. Foraging and vulnerability traits modify predator-prey body mass allometry: freshwater macroinvertebrates as a case study.

    PubMed

    Klecka, Jan; Boukal, David S

    2013-09-01

    1. Predation is often size selective, but the role of other traits of the prey and predators in their interactions is little known. This hinders our understanding of the causal links between trophic interactions and the structure of animal communities. Better knowledge of trophic traits underlying predator-prey interactions is also needed to improve models attempting to predict food web structure and dynamics from known species traits. 2. We carried out laboratory experiments with common freshwater macroinvertebrate predators (diving beetles, dragonfly and damselfly larvae and water bugs) and their prey to assess how body size and traits related to foraging (microhabitat use, feeding mode and foraging mode) and to prey vulnerability (microhabitat use, activity and escape behaviour) affect predation strength. 3. The underlying predator-prey body mass allometry characterizing mean prey size and total predation pressure was modified by feeding mode of the predators (suctorial or chewing). Suctorial predators fed upon larger prey and had ˜3 times higher mass-specific predation rate than chewing predators of the same size and may thus have stronger effect on prey abundance. 4. Strength of individual trophic links, measured as mortality of the focal prey caused by the focal predator, was determined jointly by the predator and prey body mass and their foraging and vulnerability traits. In addition to the feeding mode, interactions between prey escape behaviour (slow or fast), prey activity (sedentary or active) and predator foraging mode (searching or ambush) strongly affected prey mortality. Searching predators was ineffective in capturing fast-escape prey in comparison with the remaining predator-prey combinations, while ambush predators caused higher mortality than searching predators and the difference was larger in active prey. 5. Our results imply that the inclusion of the commonly available qualitative data on foraging traits of predators and vulnerability traits

  3. The Development and Validation of the Protective Factors Survey: A Self-Report Measure of Protective Factors against Child Maltreatment

    ERIC Educational Resources Information Center

    Counts, Jacqueline M.; Buffington, Elenor S.; Chang-Rios, Karin; Rasmussen, Heather N.; Preacher, Kristopher J.

    2010-01-01

    Objective: The objective of this study was to evaluate the internal structure of a self-report measure of multiple family-level protective factors against abuse and neglect and explore the relationship of this instrument to other measures of child maltreatment. Methods: For the exploratory factor analysis, 11 agencies from 4 states administered…

  4. Influence of time-dependent factors in the evaluation of critical infrastructure protection measures.

    SciTech Connect

    Buehring, W. A.; Samsa, M. E.; Decision and Information Sciences

    2008-03-28

    The examination of which protective measures are the most appropriate to be implemented in order to prevent, protect against, respond to, and recover from attacks on critical infrastructures and key resources typically involves a comparison of the consequences that could occur when the protective measure is implemented to those that could occur when it is not. This report describes a framework for evaluation that provides some additional capabilities for comparing optional protective measures. It illustrates some potentially important time-dependent factors, such as the implementation rate, that affect the relative pros and cons associated with widespread implementation of protective measures. It presents example results from the use of protective measures, such as detectors and pretrained responders, for an illustrative biological incident. Results show that the choice of an alternative measure can depend on whether or not policy and financial support can be maintained for extended periods of time. Choice of a time horizon greatly influences the comparison of alternatives.

  5. Prey size structure diminishes cascading effects by increasing interference competition and predation among prey.

    PubMed

    Geraldii, Nathan R

    2015-09-01

    The size of an organism can change by orders of magnitude during its lifespan. Size can determine whether an individual consumes, is consumed, competes, or avoids individuals of the same or different species. Two complementary mesocosm experiments with a tri-trophic food chain (top predator, toadfish, Opsanus tau; intermediate prey, mud crab, family Xanthidae; basal resource, oyster, Crassostrea virginica) were conducted to measure how the size of both the top predator and the intermediate prey affects consumptive and behavioral interactions in trophic cascades. In the first experiment, I systematically varied the sizes of predators and prey, respectively. The amount of crab biomass consumed was dependent on crab size and not toadfish size, but the effect of crab size did not cascade to alter oyster survival. Increased oyster survival from crab interference competition in the absence of toadfish was similar to oyster survival,from predator-avoidance behavior in the presence of a toadfish. When all crab size classes were present, crab mortality was similar in the presence and absence of toadfish, highlighting the importance of intraguild predation in food-web dynamics. The second experiment separated crab mortality by other crabs from crab mortality by predatory toadfish and found that crab mortality generally switched from intra- to interguild predation when a toadfish was present. In addition, field surveys indicated mud crab abundance and size was primarily influenced by mud crab recruitment, but not by toadfish abundance, which supports our experimental results that interactions among mud crabs have similar effects to predator-prey interactions. These findings indicate that changes in size or abundance of intermediate prey may be comparable to changes in top predator abundance in terms of trophic interactions and their transmission to lower levels, which suggests that certain types of relatively simple food chains can be resilient to the loss of higher trophic

  6. Chemotactic predator-prey dynamics.

    PubMed

    Sengupta, Ankush; Kruppa, Tobias; Löwen, Hartmut

    2011-03-01

    A discrete chemotactic predator-prey model is proposed in which the prey secrets a diffusing chemical which is sensed by the predator and vice versa. Two dynamical states corresponding to catching and escaping are identified and it is shown that steady hunting is unstable. For the escape process, the predator-prey distance is diffusive for short times but exhibits a transient subdiffusive behavior which scales as a power law t¹/³ with time t and ultimately crosses over to diffusion again. This allows us to classify the motility and dynamics of various predatory microbes and phagocytes. In particular, there is a distinct region in the parameter space where they prove to be infallible predators.

  7. Sensing the strike of a predator fish depends on the specific gravity of a prey fish.

    PubMed

    Stewart, William J; McHenry, Matthew J

    2010-11-15

    The ability of a predator fish to capture a prey fish depends on the hydrodynamics of the prey and its behavioral response to the predator's strike. Despite the importance of this predator-prey interaction to the ecology and evolution of a diversity of fish, it is unclear what factors dictate a fish's ability to evade capture. The present study evaluated how the specific gravity of a prey fish's body affects the kinematics of prey capture and the signals detected by the lateral line system of the prey during the strike of a suction-feeding predator. The specific gravity of zebrafish (Danio rerio) larvae was measured with high precision from recordings of terminal velocity in solutions of varying density. This novel method found that specific gravity decreased by ∼5% (from 1.063, N=8, to 1.011, N=35) when the swim bladder inflates. To examine the functional consequences of this change, we developed a mathematical model of the hydrodynamics of prey in the flow field created by a suction-feeding predator. This model found that the observed decrease in specific gravity due to swim bladder inflation causes an 80% reduction of the flow velocity around the prey's body. Therefore, swim bladder inflation causes a substantial reduction in the flow signal that may be sensed by the lateral line system to evade capture. These findings demonstrate that the ability of a prey fish to sense a predator depends crucially on the specific gravity of the prey.

  8. 49 CFR Appendix D to Part 192 - Criteria for Cathodic Protection and Determination of Measurements

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Criteria for Cathodic Protection and Determination.... 192, App. D Appendix D to Part 192—Criteria for Cathodic Protection and Determination of Measurements... cell. Determination of this voltage must be made with the protective current applied, and in...

  9. 49 CFR Appendix D to Part 192 - Criteria for Cathodic Protection and Determination of Measurements

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Criteria for Cathodic Protection and Determination.... 192, App. D Appendix D to Part 192—Criteria for Cathodic Protection and Determination of Measurements... cell. Determination of this voltage must be made with the protective current applied, and in...

  10. Financial Risk Protection and Universal Health Coverage: Evidence and Measurement Challenges

    PubMed Central

    Saksena, Priyanka; Hsu, Justine; Evans, David B.

    2014-01-01

    Financial risk protection is a key component of universal health coverage (UHC), which is defined as access to all needed quality health services without financial hardship. As part of the PLOS Medicine Collection on measurement of UHC, the aim of this paper is to examine and to compare and contrast existing measures of financial risk protection. The paper presents the rationale behind the methodologies for measuring financial risk protection and how this relates to UHC as well as some empirical examples of the types of measures. Additionally, the specific challenges related to monitoring inequalities in financial risk protection are discussed. The paper then goes on to examine and document the practical challenges associated with measurement of financial risk protection. This paper summarizes current thinking on the area of financial risk protection, provides novel insights, and suggests future developments that could be valuable in the context of monitoring progress towards UHC. PMID:25244520

  11. 29 CFR 1917.95 - Other protective measures.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... to 46 CFR part 160 (Type I, II, III, or V PFD) and marked for use as a work vest, for commercial use.... (1) Employees performing work that requires special protective clothing shall be directed by the... handlers, who are engaged in work in which they may be pulled into the water: (i) When such employees...

  12. 29 CFR 1917.95 - Other protective measures.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... to 46 CFR part 160 (Type I, II, III, or V PFD) and marked for use as a work vest, for commercial use.... (1) Employees performing work that requires special protective clothing shall be directed by the... handlers, who are engaged in work in which they may be pulled into the water: (i) When such employees...

  13. Examining self-protection measures guarding Adult Protective Services social workers against compassion fatigue.

    PubMed

    Bourassa, Dara

    2012-06-01

    Little research has focused on the risk factors, effects, and experiences of compassion fatigue among gerontological social workers. This qualitative study explores the experiences and perspectives of nine Adult Protective Services (APS) social workers in relation to compassion fatigue. Results show that the APS social workers combined personal characteristics and professional factors to develop boundary-setting mechanisms that protected them from experiencing the deleterious symptoms and effects of compassion fatigue. Implications center around the elements needed to implement boundaries in order to maintain a separation between the work and home environment. Suggestions for future research are provided.

  14. Tigers and their prey: Predicting carnivore densities from prey abundance

    USGS Publications Warehouse

    Karanth, K.U.; Nichols, J.D.; Kumar, N.S.; Link, W.A.; Hines, J.E.

    2004-01-01

    The goal of ecology is to understand interactions that determine the distribution and abundance of organisms. In principle, ecologists should be able to identify a small number of limiting resources for a species of interest, estimate densities of these resources at different locations across the landscape, and then use these estimates to predict the density of the focal species at these locations. In practice, however, development of functional relationships between abundances of species and their resources has proven extremely difficult, and examples of such predictive ability are very rare. Ecological studies of prey requirements of tigers Panthera tigris led us to develop a simple mechanistic model for predicting tiger density as a function of prey density. We tested our model using data from a landscape-scale long-term (1995-2003) field study that estimated tiger and prey densities in 11 ecologically diverse sites across India. We used field techniques and analytical methods that specifically addressed sampling and detectability, two issues that frequently present problems in macroecological studies of animal populations. Estimated densities of ungulate prey ranged between 5.3 and 63.8 animals per km2. Estimated tiger densities (3.2-16.8 tigers per 100 km2) were reasonably consistent with model predictions. The results provide evidence of a functional relationship between abundances of large carnivores and their prey under a wide range of ecological conditions. In addition to generating important insights into carnivore ecology and conservation, the study provides a potentially useful model for the rigorous conduct of macroecological science.

  15. Examining Self-Protection Measures Guarding Adult Protective Services Social Workers against Compassion Fatigue

    ERIC Educational Resources Information Center

    Bourassa, Dara

    2012-01-01

    Little research has focused on the risk factors, effects, and experiences of compassion fatigue among gerontological social workers. This qualitative study explores the experiences and perspectives of nine Adult Protective Services (APS) social workers in relation to compassion fatigue. Results show that the APS social workers combined personal…

  16. The Predator-Prey Relationship

    ERIC Educational Resources Information Center

    Mitchell, Charles W.

    1977-01-01

    Many children develop a mistaken attitude about the predator-prey relationship in the ecosystem. Fairy tales portray the predator as evil or worthless. This article attempts to clarify the role of the predator by giving numerous examples of the value of predators. (MA)

  17. Does colour polymorphism enhance survival of prey populations?

    PubMed

    Wennersten, Lena; Forsman, Anders

    2009-06-22

    That colour polymorphism may protect prey populations from predation is an old but rarely tested hypothesis. We examine whether colour polymorphic populations of prey exposed to avian predators in an ecologically valid visual context were exposed to increased extinction risk compared with monomorphic populations. We made 2976 artificial pastry prey, resembling Lepidoptera larvae, in four different colours and presented them in 124 monomorphic and 124 tetramorphic populations on tree trunks and branches such that they would be exposed to predation by free-living birds, and monitored their 'survival'. Among monomorphic populations, there was a significant effect of prey coloration on survival, confirming that coloration influenced susceptibility to visually oriented predators. Survival of polymorphic populations was inferior to that of monomorphic green populations, but did not differ significantly from monomorphic brown, yellow or red populations. Differences in survival within polymorphic populations paralleled those seen among monomorphic populations; the red morph most frequently went extinct first and the green morph most frequently survived the longest. Our findings do not support the traditional protective polymorphism hypothesis and are in conflict with those of earlier studies. As a possible explanation to our findings, we offer a competing 'giveaway cue' hypothesis: that polymorphic populations may include one morph that attracts the attention of predators and that polymorphic populations therefore may suffer increased predation compared with some monomorphic populations. PMID:19324729

  18. Does colour polymorphism enhance survival of prey populations?

    PubMed

    Wennersten, Lena; Forsman, Anders

    2009-06-22

    That colour polymorphism may protect prey populations from predation is an old but rarely tested hypothesis. We examine whether colour polymorphic populations of prey exposed to avian predators in an ecologically valid visual context were exposed to increased extinction risk compared with monomorphic populations. We made 2976 artificial pastry prey, resembling Lepidoptera larvae, in four different colours and presented them in 124 monomorphic and 124 tetramorphic populations on tree trunks and branches such that they would be exposed to predation by free-living birds, and monitored their 'survival'. Among monomorphic populations, there was a significant effect of prey coloration on survival, confirming that coloration influenced susceptibility to visually oriented predators. Survival of polymorphic populations was inferior to that of monomorphic green populations, but did not differ significantly from monomorphic brown, yellow or red populations. Differences in survival within polymorphic populations paralleled those seen among monomorphic populations; the red morph most frequently went extinct first and the green morph most frequently survived the longest. Our findings do not support the traditional protective polymorphism hypothesis and are in conflict with those of earlier studies. As a possible explanation to our findings, we offer a competing 'giveaway cue' hypothesis: that polymorphic populations may include one morph that attracts the attention of predators and that polymorphic populations therefore may suffer increased predation compared with some monomorphic populations.

  19. 78 FR 45573 - Compensatory and Alternative Regulatory Measures for Nuclear Power Plant Fire Protection (CARMEN...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-29

    ... COMMISSION Compensatory and Alternative Regulatory Measures for Nuclear Power Plant Fire Protection (CARMEN-FIRE) AGENCY: Nuclear Regulatory Commission. ACTION: Notice of availability; request for public comment.../CR-7135, ``Compensatory and Alternative Regulatory Measures for Nuclear Power Plant Fire...

  20. Innate prey preference overridden by familiarisation with detrimental prey in a specialised myrmecophagous predator

    NASA Astrophysics Data System (ADS)

    Pekár, Stano; Cárdenas, Manuel

    2015-02-01

    Prey-specialised spiders often do not have brood care and may not deposit eggs in the proximity of the preferred prey. Thus, naïve spiderlings are left to their own to find their focal prey. Our aim was to reveal whether the choice of a specific prey is innate and whether familiarisation with a certain prey will condition prey choice. We used the myrmecophagous spider Euryopis episinoides, which specialises on Messor ants. It finds ants using chemical cues deposited on the substrate. Naïve spiderlings were offered chemical cues from Messor and Myrmica ants and Drosophila flies. They chose significantly more chemical cues from Messor ants than those from Drosophila flies. Then spiderlings were assigned to three prey treatments: fed with Messor ants only (optimal prey), fed with Myrmica ants only (suboptimal prey) or fed with Drosophila flies only (detrimental prey) until adulthood. Every 2 weeks, all spiders from all treatments were offered chemical cues from the three prey types and the frequency of choice and latency to assuming a posture were recorded. Experienced spiderlings preferred chemical cues from the prey in which they were raised. They suffered high mortality on Drosophila flies and attained largest size on the optimal prey. We show here that majority of spiderlings are born with an innate preference to their focal prey, which can be altered by familiarisation with alternative prey, irrespective of whether such a prey is beneficial.

  1. 50 CFR 622.273 - Conservation measures for protected species.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... § 622.270(a)(1), and that has on board a pelagic longline must post inside the wheelhouse the sea turtle... turtle bycatch mitigation measures, including gear requirements and sea turtle handling requirements, as... 50 Wildlife and Fisheries 12 2014-10-01 2014-10-01 false Conservation measures for...

  2. 50 CFR 622.273 - Conservation measures for protected species.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... § 622.270(a)(1), and that has on board a pelagic longline must post inside the wheelhouse the sea turtle... turtle bycatch mitigation measures, including gear requirements and sea turtle handling requirements, as... 50 Wildlife and Fisheries 12 2013-10-01 2013-10-01 false Conservation measures for...

  3. Effects of prey size and mobility on prey-capture kinematics in leopard sharks triakis semifasciata

    PubMed

    Ferry-Graham

    1998-08-01

    Recent work on teleosts suggests that attack behaviors or kinematics may be modified by a predator on the basis of the size of the prey or the ability of the prey to sense predators and escape capture (elusivity). Sharks are generally presumed to be highly visual predators; thus, it is reasonable to expect that they might also be capable of such behavioral modulation. In this study, I investigated the effect of prey item size and type on prey-capture behavior in leopard sharks (Triakis semifasciata) that had been acclimated to feeding in the laboratory. Using high-speed video, sharks were filmed feeding on two sizes of the same prey item (thawed shrimp pieces) and two potentially more elusive prey items (live earthworms and live mud shrimp). In leopard sharks, little effect of prey elusivity was found for kinematic variables during prey capture. However, the large proportion of successful captures of the live prey suggests that they did not prove to be truly elusive prey items for the leopard shark. There were significant size effects on prey-capture kinematics, with the larger non-elusive items inducing greater head expansion during prey capture. Ram-suction index values also indicated that strikes on large, non-elusive prey had a significantly larger suction component than strikes on similar small prey items. This finding is interesting given that the two sizes of non-elusive prey item offered no differential challenge in terms of a performance consequence (reduced capture success). PMID:9679105

  4. Measuring benefits of protected area management: trends across realms and research gaps for freshwater systems.

    PubMed

    Adams, Vanessa M; Setterfield, Samantha A; Douglas, Michael M; Kennard, Mark J; Ferdinands, Keith

    2015-11-01

    Protected areas remain a cornerstone for global conservation. However, their effectiveness at halting biodiversity decline is not fully understood. Studies of protected area benefits have largely focused on measuring their impact on halting deforestation and have neglected to measure the impacts of protected areas on other threats. Evaluations that measure the impact of protected area management require more complex evaluation designs and datasets. This is the case across realms (terrestrial, freshwater, marine), but measuring the impact of protected area management in freshwater systems may be even more difficult owing to the high level of connectivity and potential for threat propagation within systems (e.g. downstream flow of pollution). We review the potential barriers to conducting impact evaluation for protected area management in freshwater systems. We contrast the barriers identified for freshwater systems to terrestrial systems and discuss potential measurable outcomes and confounders associated with protected area management across the two realms. We identify key research gaps in conducting impact evaluation in freshwater systems that relate to three of their major characteristics: variability, connectivity and time lags in outcomes. Lastly, we use Kakadu National Park world heritage area, the largest national park in Australia, as a case study to illustrate the challenges of measuring impacts of protected area management programmes for environmental outcomes in freshwater systems.

  5. Developing measurement indices to enhance protection and resilience of critical infrastructure and key resources.

    PubMed

    Fisher, Ronald E; Norman, Michael

    2010-07-01

    The US Department of Homeland Security (DHS) is developing indices to better assist in the risk management of critical infrastructures. The first of these indices is the Protective Measures Index - a quantitative index that measures overall protection across component categories: physical security, security management, security force, information sharing, protective measures and dependencies. The Protective Measures Index, which can also be recalculated as the Vulnerability Index, is a way to compare differing protective measures (eg fence versus security training). The second of these indices is the Resilience Index, which assesses a site's resilience and consists of three primary components: robustness, resourcefulness and recovery. The third index is the Criticality Index, which assesses the importance of a facility. The Criticality Index includes economic, human, governance and mass evacuation impacts. The Protective Measures Index, Resilience Index and Criticality Index are being developed as part of the Enhanced Critical Infrastructure Protection initiative that DHS protective security advisers implement across the nation at critical facilities. This paper describes two core themes: determination of the vulnerability, resilience and criticality of a facility and comparison of the indices at different facilities.

  6. Nitrogen deposition and prey nitrogen uptake control the nutrition of the carnivorous plant Drosera rotundifolia.

    PubMed

    Millett, J; Foot, G W; Svensson, B M

    2015-04-15

    Nitrogen (N) deposition has important negative impacts on natural and semi-natural ecosystems, impacting on biotic interactions across trophic levels. Low-nutrient systems are particularly sensitive to changes in N inputs and are therefore more vulnerable to N deposition. Carnivorous plants are often part of these ecosystems partly because of the additional nutrients obtained from prey. We studied the impact of N deposition on the nutrition of the carnivorous plant Drosera rotundifolia growing on 16 ombrotrophic bogs across Europe. We measured tissue N, phosphorus (P) and potassium (K) concentrations and prey and root N uptake using a natural abundance stable isotope approach. Our aim was to test the impact of N deposition on D. rotundifolia prey and root N uptake, and nutrient stoichiometry. D. rotundifolia root N uptake was strongly affected by N deposition, possibly resulting in reduced N limitation. The contribution of prey N to the N contained in D. rotundifolia ranged from 20 to 60%. N deposition reduced the maximum amount of N derived from prey, but this varied below this maximum. D. rotundifolia tissue N concentrations were a product of both root N availability and prey N uptake. Increased prey N uptake was correlated with increased tissue P concentrations indicating uptake of P from prey. N deposition therefore reduced the strength of a carnivorous plant-prey interaction, resulting in a reduction in nutrient transfer between trophic levels. We suggest that N deposition has a negative impact on D. rotundifolia and that responses to N deposition might be strongly site specific.

  7. Prey use and provisioning rates of urban-nesting Mississippi Kites in west Texas

    USGS Publications Warehouse

    Welch, Brandi C.; Boal, Clint W.

    2015-01-01

    Urban ecosystems are attractive to several raptor species, including the Mississippi Kite (Ictinia mississippiensis). To better understand the niche filled by urban-nesting Mississippi Kites, we observed nesting kites at 10 nests for a total of 269 hr during the breeding seasons of 2010 and 2011. We assessed prey delivery rates and prey use within and between years, evaluated the influences of nestling age, time of day, day of year, and local atmospheric conditions on delivery rates, and examined provisioning rates by male and female kites. A 62% decrease in the prey delivery rate, measured by the number of prey deliveries, from 2010 to 2011 was likely attributable to extreme heat and drought during the 2011 breeding season. However, total biomass of identified deliveries increased 38.9% in 2011 due to an increase in the percentage of avian prey (from 1% to 16% of identified deliveries). We suspect that differences in weather conditions between years influenced the type of prey delivered, and our modeling efforts indicated that year, nestling age, time of day, and temperature best explained the number of prey deliveries made per hour. On average, females delivered more prey items than males, but variability among nests suggested additional factors may influence parental effort. Our results suggest that Mississippi Kites exhibit prey switching under differing conditions.

  8. 30 CFR 282.28 - Environmental protection measures.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Section 282.28 Mineral Resources BUREAU OF OCEAN ENERGY MANAGEMENT, REGULATION, AND ENFORCEMENT... measures. (a) Exploration, testing, development, production, and processing activities proposed to be... Director to assess the impacts of exploration, testing, mining, and processing activities on...

  9. When attempts at robbing prey turn fatal.

    PubMed

    Dejean, Alain; Corbara, Bruno; Azémar, Frédéric; Carpenter, James M

    2012-07-01

    Because group-hunting arboreal ants spread-eagle insect prey for a long time before retrieving them, these prey can be coveted by predatory flying insects. Yet, attempting to rob these prey is risky if the ant species is also an effective predator. Here, we show that trying to rob prey from Azteca andreae workers is a fatal error as 268 out of 276 potential cleptobionts (97.1 %) were captured in turn. The ant workers hunt in a group and use the "Velcro®" principle to cling firmly to the leaves of their host tree, permitting them to capture very large prey. Exceptions were one social wasp, plus some Trigona spp. workers and flies that landed directly on the prey and were able to take off immediately when attacked. We conclude that in this situation, previously captured prey attract potential cleptobionts that are captured in turn in most of the cases.

  10. When attempts at robbing prey turn fatal.

    PubMed

    Dejean, Alain; Corbara, Bruno; Azémar, Frédéric; Carpenter, James M

    2012-07-01

    Because group-hunting arboreal ants spread-eagle insect prey for a long time before retrieving them, these prey can be coveted by predatory flying insects. Yet, attempting to rob these prey is risky if the ant species is also an effective predator. Here, we show that trying to rob prey from Azteca andreae workers is a fatal error as 268 out of 276 potential cleptobionts (97.1 %) were captured in turn. The ant workers hunt in a group and use the "Velcro®" principle to cling firmly to the leaves of their host tree, permitting them to capture very large prey. Exceptions were one social wasp, plus some Trigona spp. workers and flies that landed directly on the prey and were able to take off immediately when attacked. We conclude that in this situation, previously captured prey attract potential cleptobionts that are captured in turn in most of the cases. PMID:22710934

  11. Fear on the move: predator hunting mode predicts variation in prey mortality and plasticity in prey spatial response.

    PubMed

    Miller, Jennifer R B; Ament, Judith M; Schmitz, Oswald J

    2014-01-01

    Ecologists have long searched for a framework of a priori species traits to help predict predator-prey interactions in food webs. Empirical evidence has shown that predator hunting mode and predator and prey habitat domain are useful traits for explaining predator-prey interactions. Yet, individual experiments have yet to replicate predator hunting mode, calling into question whether predator impacts can be attributed to hunting mode or merely species identity. We tested the effects of spider predators with sit-and-wait, sit-and-pursue and active hunting modes on grasshopper habitat domain, activity and mortality in a grassland system. We replicated hunting mode by testing two spider predator species of each hunting mode on the same grasshopper prey species. We observed grasshoppers with and without each spider species in behavioural cages and measured their mortality rates, movements and habitat domains. We likewise measured the movements and habitat domains of spiders to characterize hunting modes. We found that predator hunting mode explained grasshopper mortality and spider and grasshopper movement activity and habitat domain size. Sit-and-wait spider predators covered small distances over a narrow domain space and killed fewer grasshoppers than sit-and-pursue and active predators, which ranged farther distances across broader domains and killed more grasshoppers, respectively. Prey adjusted their activity levels and horizontal habitat domains in response to predator presence and hunting mode: sedentary sit-and-wait predators with narrow domains caused grasshoppers to reduce activity in the same-sized domain space; more mobile sit-and-pursue predators with broader domains caused prey to reduce their activity within a contracted horizontal (but not vertical) domain space; and highly mobile active spiders led grasshoppers to increase their activity across the same domain area. All predators impacted prey activity, and sit-and-pursue predators generated strong

  12. Feeding by the newly described mixotrophic dinoflagellate Paragymnodinium shiwhaense: feeding mechanism, prey species, and effect of prey concentration.

    PubMed

    Yoo, Yeong Du; Jeong, Hae Jin; Kang, Nam Seon; Song, Jae Yoon; Kim, Kwang Young; Lee, Gitack; Kim, Juhyoung

    2010-01-01

    To investigate the feeding by the newly described mixotrophic dinoflagellate Paragymnodinium shiwhaense (GenBank accession number=AM408889), we explored the feeding process and the kinds of prey species that P. shiwhaense is able to feed on using several different types of microscopes, including a transmission electron microscope and high-resolution video-microscopy. In addition, we measured the growth and ingestion rates of P. shiwhaense on its optimal algal prey Amphidinium carterae as a function of prey concentration. We also measured these parameters for edible prey at a single concentration at which the growth and ingestion rates of P. shiwhaense on A. carterae were saturated. Paragymnodinium shiwhaense feed on algal prey using a peduncle after anchoring the prey by a tow filament. Among the algal prey offered, P. shiwhaense ingested small algal species that had equivalent spherical diameters (ESDs) < or =11 microm (e.g. the prymnesiophyte Isochrysis galbana, the cryptophytes Teleaulax sp. and Rhodomonas salina, the raphidophyte Heterosigma akashiwo, and the dinoflagellates Heterocapsa rotundata and A. carterae). However, it did not feed on larger algal species that had ESDs > or =12 microm (e.g. the dinoflagellates Prorocentrum minimum, Heterocapsa triquetra, Scrippsiella trochoidea, Alexandrium tamarense, Prorocentrum micans, Gymnodinium catenatum, Akashiwo sanguinea, and Lingulodinium polyedrum) or the small diatom Skeletonema costatum. The specific growth rates for P. shiwhaense feeding upon A. carterae increased rapidly with increasing mean prey concentration before saturating at concentrations of ca. 350 ng C/ml (5,000 cells/ml). The maximum specific growth rate (i.e. mixotrophic growth) of P. shiwhaense on A. carterae was 1.097/d at 20 degrees C under a 14:10 h light-dark cycle of 20 microE/m(2)/s, while its growth rate (i.e. phototrophic growth) under the same light conditions without added prey was -0.224/d. The maximum ingestion and clearance rates

  13. Relative availability of natural prey versus livestock predicts landscape suitability for cheetahs Acinonyx jubatus in Botswana.

    PubMed

    Winterbach, Hanlie E K; Winterbach, Christiaan W; Boast, Lorraine K; Klein, Rebecca; Somers, Michael J

    2015-01-01

    Prey availability and human-carnivore conflict are strong determinants that govern the spatial distribution and abundance of large carnivore species and determine the suitability of areas for their conservation. For wide-ranging large carnivores such as cheetahs (Acinonyx jubatus), additional conservation areas beyond protected area boundaries are crucial to effectively conserve them both inside and outside protected areas. Although cheetahs prefer preying on wild prey, they also cause conflict with people by predating on especially small livestock. We investigated whether the distribution of cheetahs' preferred prey and small livestock biomass could be used to explore the potential suitability of agricultural areas in Botswana for the long-term persistence of its cheetah population. We found it gave a good point of departure for identifying priority areas for land management, the threat to connectivity between cheetah populations, and areas where the reduction and mitigation of human-cheetah conflict is critical. Our analysis showed the existence of a wide prey base for cheetahs across large parts of Botswana's agricultural areas, which provide additional large areas with high conservation potential. Twenty percent of wild prey biomass appears to be the critical point to distinguish between high and low probable levels of human-cheetah conflict. We identified focal areas in the agricultural zones where restoring wild prey numbers in concurrence with effective human-cheetah conflict mitigation efforts are the most immediate conservation strategies needed to maintain Botswana's still large and contiguous cheetah population.

  14. Relative availability of natural prey versus livestock predicts landscape suitability for cheetahs Acinonyx jubatus in Botswana

    PubMed Central

    Winterbach, Christiaan W.; Boast, Lorraine K.; Klein, Rebecca; Somers, Michael J.

    2015-01-01

    Prey availability and human-carnivore conflict are strong determinants that govern the spatial distribution and abundance of large carnivore species and determine the suitability of areas for their conservation. For wide-ranging large carnivores such as cheetahs (Acinonyx jubatus), additional conservation areas beyond protected area boundaries are crucial to effectively conserve them both inside and outside protected areas. Although cheetahs prefer preying on wild prey, they also cause conflict with people by predating on especially small livestock. We investigated whether the distribution of cheetahs’ preferred prey and small livestock biomass could be used to explore the potential suitability of agricultural areas in Botswana for the long-term persistence of its cheetah population. We found it gave a good point of departure for identifying priority areas for land management, the threat to connectivity between cheetah populations, and areas where the reduction and mitigation of human-cheetah conflict is critical. Our analysis showed the existence of a wide prey base for cheetahs across large parts of Botswana’s agricultural areas, which provide additional large areas with high conservation potential. Twenty percent of wild prey biomass appears to be the critical point to distinguish between high and low probable levels of human-cheetah conflict. We identified focal areas in the agricultural zones where restoring wild prey numbers in concurrence with effective human-cheetah conflict mitigation efforts are the most immediate conservation strategies needed to maintain Botswana’s still large and contiguous cheetah population. PMID:26213646

  15. From cues to signals: evolution of interspecific communication via aposematism and mimicry in a predator-prey system.

    PubMed

    Lehmann, Kenna D S; Goldman, Brian W; Dworkin, Ian; Bryson, David M; Wagner, Aaron P

    2014-01-01

    Current theory suggests that many signaling systems evolved from preexisting cues. In aposematic systems, prey warning signals benefit both predator and prey. When the signal is highly beneficial, a third species often evolves to mimic the toxic species, exploiting the signaling system for its own protection. We investigated the evolutionary dynamics of predator cue utilization and prey signaling in a digital predator-prey system in which prey could evolve to alter their appearance to mimic poison-free or poisonous prey. In predators, we observed rapid evolution of cue recognition (i.e. active behavioral responses) when presented with sufficiently poisonous prey. In addition, active signaling (i.e. mimicry) evolved in prey under all conditions that led to cue utilization. Thus we show that despite imperfect and dishonest signaling, given a high cost of consuming poisonous prey, complex systems of interspecific communication can evolve via predator cue recognition and prey signal manipulation. This provides evidence supporting hypotheses that cues may serve as stepping-stones in the evolution of more advanced communication and signaling systems that incorporate information about the environment.

  16. From Cues to Signals: Evolution of Interspecific Communication via Aposematism and Mimicry in a Predator-Prey System

    PubMed Central

    Lehmann, Kenna D. S.; Goldman, Brian W.; Dworkin, Ian; Bryson, David M.; Wagner, Aaron P.

    2014-01-01

    Current theory suggests that many signaling systems evolved from preexisting cues. In aposematic systems, prey warning signals benefit both predator and prey. When the signal is highly beneficial, a third species often evolves to mimic the toxic species, exploiting the signaling system for its own protection. We investigated the evolutionary dynamics of predator cue utilization and prey signaling in a digital predator-prey system in which prey could evolve to alter their appearance to mimic poison-free or poisonous prey. In predators, we observed rapid evolution of cue recognition (i.e. active behavioral responses) when presented with sufficiently poisonous prey. In addition, active signaling (i.e. mimicry) evolved in prey under all conditions that led to cue utilization. Thus we show that despite imperfect and dishonest signaling, given a high cost of consuming poisonous prey, complex systems of interspecific communication can evolve via predator cue recognition and prey signal manipulation. This provides evidence supporting hypotheses that cues may serve as stepping-stones in the evolution of more advanced communication and signaling systems that incorporate information about the environment. PMID:24614755

  17. Diet and lifestyle measures to protect the ageing heart.

    PubMed

    Stanner, Sara

    2009-05-01

    Coronary heart disease (CHD) is a leading cause of mortality and morbidity in the UK and risk increases substantially with age. It is estimated that more than 1 in 3 men and around 1 in 4 women aged 75 and over is currently living with the condition. Evidence from epidemiologic studies indicates that the same factors that are associated with increased risk of CHD in middle-aged people are relevant in older adults. Clinical trials have shown that changing these risk factors in older adults can reduce CHD risk as effectively as it does in middle-aged adults. A diet that is low in fat (particularly saturates), rich in carbohydrate (particularly whole-grains), contains plenty of fruits and vegetables, and a portion of oily fish each week and is not too high in salt can offer significant protection against heart disease. Such diets, together with regular physical activity, avoidance of smoking, sensible drinking habits and maintenance of a healthy body weight, may prevent the majority of cardiovascular disease in Western populations. The greatest benefit will be achieved by adopting these habits throughout the life-course.

  18. Interactions between benthic predators and zooplanktonic prey are affected by turbulent waves.

    PubMed

    Robinson, H E; Finelli, C M; Koehl, M A R

    2013-11-01

    Predators capture prey in complex and variable environments. In the ocean, bottom-dwelling (benthic) organisms are subjected to water currents, waves, and turbulent eddies. For benthic predators that feed on small animals carried in the water (zooplankton), flow not only delivers prey, but can also shape predator-prey interactions. Benthic passive suspension feeders collect prey delivered by movement of ambient water onto capture-surfaces, whereas motile benthic predators, such as burrow-dwelling fish, dart out to catch passing zooplankton. How does the flow of ambient water affect these contrasting modes of predation by benthic zooplanktivores? We studied the effects of turbulent, wavy flow on the encounter, capture, and retention of motile zooplanktonic prey (copepods, Acartia spp.) by passive benthic suspension feeders (sea anemones, Anthopleura elegantissima). Predator-prey interactions were video-recorded in a wave-generating flume under two regimes of oscillating flow with different peak wave velocities and levels of turbulent kinetic energy ("weak" and "strong" waves). Rates of encounter (number of prey passing through a sea anemone's capture zone per time), capture (prey contacting and sticking to tentacles per time), and retention (prey retained on tentacles, without struggling free or washing off, per time) were measured at both strengths of waves. Strong waves enhanced encounter rates both for dead copepods and for actively swimming copepods, but there was so much variability in the behavior of the live prey that the effect of wave strength on encounter rates was not significant. Trapping efficiency (number of prey retained per number encountered) was the same in both flow regimes because, although fewer prey executed maneuvers to escape capture in strong waves, more of the captured prey was washed off the predators' tentacles. Although peak water velocities and turbulence of waves did not affect feeding rates of passive suspension-feeding sea anemones

  19. 50 CFR 622.10 - Conservation measures for protected resources.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... constitutes removal of pelagic longline gear. (b)(1) Sea turtle conservation measures. (i) The owner or... pelagic longline must post inside the wheelhouse the sea turtle handling and release guidelines provided by NMFS. Such owner or operator must also comply with the sea turtle bycatch mitigation...

  20. 50 CFR 622.179 - Conservation measures for protected resources.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    .../headboats—(1) Sea turtle conservation measures. (i) The owner or operator of a vessel for which a commercial... for Sea Turtle Release With Minimal Injury,” and must post inside the wheelhouse, or in an easily viewable area if no wheelhouse, the sea turtle handling and release guidelines provided by NMFS. (ii)...

  1. 50 CFR 622.179 - Conservation measures for protected resources.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    .../headboats—(1) Sea turtle conservation measures. (i) The owner or operator of a vessel for which a commercial... for Sea Turtle Release With Minimal Injury,” and must post inside the wheelhouse, or in an easily viewable area if no wheelhouse, the sea turtle handling and release guidelines provided by NMFS. (ii)...

  2. 50 CFR 622.10 - Conservation measures for protected resources.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... constitutes removal of pelagic longline gear. (b)(1) Sea turtle conservation measures. (i) The owner or... pelagic longline must post inside the wheelhouse the sea turtle handling and release guidelines provided by NMFS. Such owner or operator must also comply with the sea turtle bycatch mitigation...

  3. 50 CFR 622.10 - Conservation measures for protected resources.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... constitutes removal of pelagic longline gear. (b)(1) Sea turtle conservation measures. (i) The owner or... pelagic longline must post inside the wheelhouse the sea turtle handling and release guidelines provided by NMFS. Such owner or operator must also comply with the sea turtle bycatch mitigation...

  4. Acoustic shadows help gleaning bats find prey, but may be defeated by prey acoustic camouflage on rough surfaces

    PubMed Central

    Clare, Elizabeth L; Holderied, Marc W

    2015-01-01

    Perceptual abilities of animals, like echolocating bats, are difficult to study because they challenge our understanding of non-visual senses. We used novel acoustic tomography to convert echoes into visual representations and compare these cues to traditional echo measurements. We provide a new hypothesis for the echo-acoustic basis of prey detection on surfaces. We propose that bats perceive a change in depth profile and an ‘acoustic shadow’ cast by prey. The shadow is more salient than prey echoes and particularly strong on smooth surfaces. This may explain why bats look for prey on flat surfaces like leaves using scanning behaviour. We propose that rather than forming search images for prey, whose characteristics are unpredictable, predators may look for disruptions to the resting surface (acoustic shadows). The fact that the acoustic shadow is much fainter on rougher resting surfaces provides the first empirical evidence for ‘acoustic camouflage’ as an anti-predator defence mechanism. DOI: http://dx.doi.org/10.7554/eLife.07404.001 PMID:26327624

  5. Measurements of the UVR protection provided by hats used at school.

    PubMed

    Gies, Peter; Javorniczky, John; Roy, Colin; Henderson, Stuart

    2006-01-01

    The importance of protection against solar ultraviolet radiation (UVR) in childhood has lead to SunSmart policies at Australian schools, in particular primary schools, where children are encouraged and in many cases required to wear hats at school. Hat styles change regularly and the UVR protection provided by some of the hat types currently used and recommended for sun protection by the various Australian state cancer councils had not been previously evaluated. The UVR protection of the hats was measured using UVR sensitive polysulphone film badges attached to different facial sites on rotating headforms. The sun protection type hats included in this study were broad-brimmed hats, "bucket hats" and legionnaires hats. Baseball caps, which are very popular, were also included. The broad-brimmed hats and bucket hats provided the most UVR protection for the six different sites about the face and head. Legionnaires hats also provided satisfactory UVR protection, but the caps did not provide UVR protection to many of the facial sites. The highest measured UVR protection factors for facial sites other than the forehead were 8 to 10, indicating that, while some hats can be effective, they need to be used in combination with other forms of UVR protection.

  6. Prey Patch Patterns Predict Habitat Use by Top Marine Predators with Diverse Foraging Strategies

    PubMed Central

    Benoit-Bird, Kelly J.; Battaile, Brian C.; Heppell, Scott A.; Hoover, Brian; Irons, David; Jones, Nathan; Kuletz, Kathy J.; Nordstrom, Chad A.; Paredes, Rosana; Suryan, Robert M.; Waluk, Chad M.; Trites, Andrew W.

    2013-01-01

    Spatial coherence between predators and prey has rarely been observed in pelagic marine ecosystems. We used measures of the environment, prey abundance, prey quality, and prey distribution to explain the observed distributions of three co-occurring predator species breeding on islands in the southeastern Bering Sea: black-legged kittiwakes (Rissa tridactyla), thick-billed murres (Uria lomvia), and northern fur seals (Callorhinus ursinus). Predictions of statistical models were tested using movement patterns obtained from satellite-tracked individual animals. With the most commonly used measures to quantify prey distributions - areal biomass, density, and numerical abundance - we were unable to find a spatial relationship between predators and their prey. We instead found that habitat use by all three predators was predicted most strongly by prey patch characteristics such as depth and local density within spatial aggregations. Additional prey patch characteristics and physical habitat also contributed significantly to characterizing predator patterns. Our results indicate that the small-scale prey patch characteristics are critical to how predators perceive the quality of their food supply and the mechanisms they use to exploit it, regardless of time of day, sampling year, or source colony. The three focal predator species had different constraints and employed different foraging strategies – a shallow diver that makes trips of moderate distance (kittiwakes), a deep diver that makes trip of short distances (murres), and a deep diver that makes extensive trips (fur seals). However, all three were similarly linked by patchiness of prey rather than by the distribution of overall biomass. This supports the hypothesis that patchiness may be critical for understanding predator-prey relationships in pelagic marine systems more generally. PMID:23301063

  7. Flocking and feeding in the fiddler crab ( UCA tangeri): Prey availability as risk-taking behaviour

    NASA Astrophysics Data System (ADS)

    Ens, B. J.; Klaassen, M.; Zwarts, L.

    For a full understanding of prey availability, it is necessary to study risk-taking behaviour of the prey. Fiddler crabs are ideally suited for such a study, as they have to leave their safe burrow to feed on the surface of the intertidal flats during low tide, thereby exposing themselves to avian predators. A study in an intertidal area along the coast of Mauritania showed that small crabs always stayed in the vicinity of their burrow, but large crabs wandered in large flocks (also referred to as droves) to feed on sea-grass beds downshore. Transplanting downshore feeding substrate to the burrowing zone of the small crabs proved that they too preferred to feed on it. Since small crabs can be preyed upon by more species of birds, this suggests that the decision not to leave the burrowing zone might be related to the risk of being fed upon by birds. We calculated predation risk from measurements on the density and feeding activity of the crabs, as well as the feeding density, the intake rate and the size selection of the avian predators. Per hour on the surface, crabs in a flock were more at risk than crabs feeding near their burrow. Thus, though flocking crabs may have benefited from 'swamping the predator' by emerging in maximum numbers during some tides only, this did not reduce their risk of predation below that of non-flocking crabs. Furthermore we found that irrespective of activity, large crabs suffered a higher mortality per tide from avian predators than small crabs. This suggests that large crabs could not sufficiently reduce their foraging time to compensate for the increased risk while foraging in a flock, even though they probably experienced better feeding conditions than small crabs staying near their burrow. The greater energy demands of large crabs were reflected in a greater surface area grazed. Thus, with increasing size a fiddler crab has to feed further away from its burrow and so may derive less protection from staying near to it. It seems that

  8. The Effect of Structural Complexity, Prey Density, and “Predator-Free Space” on Prey Survivorship at Created Oyster Reef Mesocosms

    PubMed Central

    Humphries, Austin T.; La Peyre, Megan K.; Decossas, Gary A.

    2011-01-01

    Interactions between predators and their prey are influenced by the habitat they occupy. Using created oyster (Crassostrea virginica) reef mesocosms, we conducted a series of laboratory experiments that created structure and manipulated complexity as well as prey density and “predator-free space” to examine the relationship between structural complexity and prey survivorship. Specifically, volume and spatial arrangement of oysters as well as prey density were manipulated, and the survivorship of prey (grass shrimp, Palaemonetes pugio) in the presence of a predator (wild red drum, Sciaenops ocellatus) was quantified. We found that the presence of structure increased prey survivorship, and that increasing complexity of this structure further increased survivorship, but only to a point. This agrees with the theory that structural complexity may influence predator-prey dynamics, but that a threshold exists with diminishing returns. These results held true even when prey density was scaled to structural complexity, or the amount of “predator-free space” was manipulated within our created reef mesocosms. The presence of structure and its complexity (oyster shell volume) were more important in facilitating prey survivorship than perceived refugia or density-dependent prey effects. A more accurate indicator of refugia might require “predator-free space” measures that also account for the available area within the structure itself (i.e., volume) and not just on the surface of a structure. Creating experiments that better mimic natural conditions and test a wider range of “predator-free space” are suggested to better understand the role of structural complexity in oyster reefs and other complex habitats. PMID:22145037

  9. 43 CFR 3272.12 - What environmental protection measures must I include in my utilization plan?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... minimum, your proposed measures to: (1) Prevent or control fires; (2) Prevent soil erosion; (3) Protect... resources; (6) Minimize air and noise pollution; and (7) Minimize hazards to public health and safety...

  10. 43 CFR 3272.12 - What environmental protection measures must I include in my utilization plan?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... minimum, your proposed measures to: (1) Prevent or control fires; (2) Prevent soil erosion; (3) Protect... resources; (6) Minimize air and noise pollution; and (7) Minimize hazards to public health and safety...

  11. 43 CFR 3272.12 - What environmental protection measures must I include in my utilization plan?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... minimum, your proposed measures to: (1) Prevent or control fires; (2) Prevent soil erosion; (3) Protect... resources; (6) Minimize air and noise pollution; and (7) Minimize hazards to public health and safety...

  12. 43 CFR 3272.12 - What environmental protection measures must I include in my utilization plan?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... minimum, your proposed measures to: (1) Prevent or control fires; (2) Prevent soil erosion; (3) Protect... resources; (6) Minimize air and noise pollution; and (7) Minimize hazards to public health and safety...

  13. Measuring impact of protected area management interventions: current and future use of the Global Database of Protected Area Management Effectiveness.

    PubMed

    Coad, Lauren; Leverington, Fiona; Knights, Kathryn; Geldmann, Jonas; Eassom, April; Kapos, Valerie; Kingston, Naomi; de Lima, Marcelo; Zamora, Camilo; Cuardros, Ivon; Nolte, Christoph; Burgess, Neil D; Hockings, Marc

    2015-11-01

    Protected areas (PAs) are at the forefront of conservation efforts, and yet despite considerable progress towards the global target of having 17% of the world's land area within protected areas by 2020, biodiversity continues to decline. The discrepancy between increasing PA coverage and negative biodiversity trends has resulted in renewed efforts to enhance PA effectiveness. The global conservation community has conducted thousands of assessments of protected area management effectiveness (PAME), and interest in the use of these data to help measure the conservation impact of PA management interventions is high. Here, we summarize the status of PAME assessment, review the published evidence for a link between PAME assessment results and the conservation impacts of PAs, and discuss the limitations and future use of PAME data in measuring the impact of PA management interventions on conservation outcomes. We conclude that PAME data, while designed as a tool for local adaptive management, may also help to provide insights into the impact of PA management interventions from the local-to-global scale. However, the subjective and ordinal characteristics of the data present significant limitations for their application in rigorous scientific impact evaluations, a problem that should be recognized and mitigated where possible. PMID:26460133

  14. Measuring impact of protected area management interventions: current and future use of the Global Database of Protected Area Management Effectiveness.

    PubMed

    Coad, Lauren; Leverington, Fiona; Knights, Kathryn; Geldmann, Jonas; Eassom, April; Kapos, Valerie; Kingston, Naomi; de Lima, Marcelo; Zamora, Camilo; Cuardros, Ivon; Nolte, Christoph; Burgess, Neil D; Hockings, Marc

    2015-11-01

    Protected areas (PAs) are at the forefront of conservation efforts, and yet despite considerable progress towards the global target of having 17% of the world's land area within protected areas by 2020, biodiversity continues to decline. The discrepancy between increasing PA coverage and negative biodiversity trends has resulted in renewed efforts to enhance PA effectiveness. The global conservation community has conducted thousands of assessments of protected area management effectiveness (PAME), and interest in the use of these data to help measure the conservation impact of PA management interventions is high. Here, we summarize the status of PAME assessment, review the published evidence for a link between PAME assessment results and the conservation impacts of PAs, and discuss the limitations and future use of PAME data in measuring the impact of PA management interventions on conservation outcomes. We conclude that PAME data, while designed as a tool for local adaptive management, may also help to provide insights into the impact of PA management interventions from the local-to-global scale. However, the subjective and ordinal characteristics of the data present significant limitations for their application in rigorous scientific impact evaluations, a problem that should be recognized and mitigated where possible.

  15. Measuring impact of protected area management interventions: current and future use of the Global Database of Protected Area Management Effectiveness

    PubMed Central

    Coad, Lauren; Leverington, Fiona; Knights, Kathryn; Geldmann, Jonas; Eassom, April; Kapos, Valerie; Kingston, Naomi; de Lima, Marcelo; Zamora, Camilo; Cuardros, Ivon; Nolte, Christoph; Burgess, Neil D.; Hockings, Marc

    2015-01-01

    Protected areas (PAs) are at the forefront of conservation efforts, and yet despite considerable progress towards the global target of having 17% of the world's land area within protected areas by 2020, biodiversity continues to decline. The discrepancy between increasing PA coverage and negative biodiversity trends has resulted in renewed efforts to enhance PA effectiveness. The global conservation community has conducted thousands of assessments of protected area management effectiveness (PAME), and interest in the use of these data to help measure the conservation impact of PA management interventions is high. Here, we summarize the status of PAME assessment, review the published evidence for a link between PAME assessment results and the conservation impacts of PAs, and discuss the limitations and future use of PAME data in measuring the impact of PA management interventions on conservation outcomes. We conclude that PAME data, while designed as a tool for local adaptive management, may also help to provide insights into the impact of PA management interventions from the local-to-global scale. However, the subjective and ordinal characteristics of the data present significant limitations for their application in rigorous scientific impact evaluations, a problem that should be recognized and mitigated where possible. PMID:26460133

  16. The effects of prey species on food conversion efficiency and growth of an insectivorous lizard.

    PubMed

    Rich, C Nelson; Talent, Larry G

    2008-05-01

    Little is known about the effects of different prey species on lizard growth. We conducted a 6-week study to determine the relative effects of prey species on growth parameters of hatchling western fence lizards, Sceloporus occidentalis. Lizards were fed house cricket nymphs, Acheta domesticus, or mealworm larvae, Tenebrio molitor. The effects of prey species on growth were determined by measuring prey consumption, gross conversion efficiency of food [gain in mass (g)/food consumed (g)], gain in mass, and gain in snout-vent length. Lizards grew well on both the prey species. However, lizards that fed on crickets consumed a significantly higher percentage of their body mass per day than those fed mealworms. Nevertheless, lizards that consumed mealworms ingested significantly more metabolizable energy, had significantly higher food conversion efficiencies, significantly higher daily gains in mass, and significantly greater total growth in mass than lizards that fed on crickets. PMID:19360616

  17. Coevolution can reverse predator-prey cycles.

    PubMed

    Cortez, Michael H; Weitz, Joshua S

    2014-05-20

    A hallmark of Lotka-Volterra models, and other ecological models of predator-prey interactions, is that in predator-prey cycles, peaks in prey abundance precede peaks in predator abundance. Such models typically assume that species life history traits are fixed over ecologically relevant time scales. However, the coevolution of predator and prey traits has been shown to alter the community dynamics of natural systems, leading to novel dynamics including antiphase and cryptic cycles. Here, using an eco-coevolutionary model, we show that predator-prey coevolution can also drive population cycles where the opposite of canonical Lotka-Volterra oscillations occurs: predator peaks precede prey peaks. These reversed cycles arise when selection favors extreme phenotypes, predator offense is costly, and prey defense is effective against low-offense predators. We present multiple datasets from phage-cholera, mink-muskrat, and gyrfalcon-rock ptarmigan systems that exhibit reversed-peak ordering. Our results suggest that such cycles are a potential signature of predator-prey coevolution and reveal unique ways in which predator-prey coevolution can shape, and possibly reverse, community dynamics.

  18. Coevolution can reverse predator-prey cycles.

    PubMed

    Cortez, Michael H; Weitz, Joshua S

    2014-05-20

    A hallmark of Lotka-Volterra models, and other ecological models of predator-prey interactions, is that in predator-prey cycles, peaks in prey abundance precede peaks in predator abundance. Such models typically assume that species life history traits are fixed over ecologically relevant time scales. However, the coevolution of predator and prey traits has been shown to alter the community dynamics of natural systems, leading to novel dynamics including antiphase and cryptic cycles. Here, using an eco-coevolutionary model, we show that predator-prey coevolution can also drive population cycles where the opposite of canonical Lotka-Volterra oscillations occurs: predator peaks precede prey peaks. These reversed cycles arise when selection favors extreme phenotypes, predator offense is costly, and prey defense is effective against low-offense predators. We present multiple datasets from phage-cholera, mink-muskrat, and gyrfalcon-rock ptarmigan systems that exhibit reversed-peak ordering. Our results suggest that such cycles are a potential signature of predator-prey coevolution and reveal unique ways in which predator-prey coevolution can shape, and possibly reverse, community dynamics. PMID:24799689

  19. The optimal sampling strategy for unfamiliar prey.

    PubMed

    Sherratt, Thomas N

    2011-07-01

    Precisely how predators solve the problem of sampling unfamiliar prey types is central to our understanding of the evolution of a variety of antipredator defenses, ranging from Müllerian mimicry to polymorphism. When predators encounter a novel prey item then they must decide whether to take a risk and attack it, thereby gaining a potential meal and valuable information, or avoid such prey altogether. Moreover, if predators initially attack the unfamiliar prey, then at some point(s) they should decide to cease sampling if evidence mounts that the type is on average unprofitable to attack. Here, I cast this problem as a "two-armed bandit," the standard metaphor for exploration-exploitation trade-offs. I assume that as predators encounter and attack unfamiliar prey they use Bayesian inference to update both their beliefs as to the likelihood that individuals of this type are chemically defended, and the probability of seeing the prey type in the future. I concurrently use dynamic programming to identify the critical informational states at which predator should cease sampling. The model explains why predators sample more unprofitable prey before complete rejection when the prey type is common and explains why predators exhibit neophobia when the unfamiliar prey type is perceived to be rare.

  20. Coevolution can reverse predator–prey cycles

    PubMed Central

    Cortez, Michael H.; Weitz, Joshua S.

    2014-01-01

    A hallmark of Lotka–Volterra models, and other ecological models of predator–prey interactions, is that in predator–prey cycles, peaks in prey abundance precede peaks in predator abundance. Such models typically assume that species life history traits are fixed over ecologically relevant time scales. However, the coevolution of predator and prey traits has been shown to alter the community dynamics of natural systems, leading to novel dynamics including antiphase and cryptic cycles. Here, using an eco-coevolutionary model, we show that predator–prey coevolution can also drive population cycles where the opposite of canonical Lotka–Volterra oscillations occurs: predator peaks precede prey peaks. These reversed cycles arise when selection favors extreme phenotypes, predator offense is costly, and prey defense is effective against low-offense predators. We present multiple datasets from phage–cholera, mink–muskrat, and gyrfalcon–rock ptarmigan systems that exhibit reversed-peak ordering. Our results suggest that such cycles are a potential signature of predator–prey coevolution and reveal unique ways in which predator–prey coevolution can shape, and possibly reverse, community dynamics. PMID:24799689

  1. Quantifying the Effects of Predator and Prey Body Size on Sea Star Feeding Behaviors.

    PubMed

    Gooding, Rebecca A; Harley, Christopher D G

    2015-06-01

    Body size plays a crucial role in determining the strength of species interactions, population dynamics, and community structure. We measured how changes in body size affect the trophic relationship between the sea star Pisaster ochraceus and its prey, the mussel Mytilus trossulus. We tested the effects of a wide range of predator and prey sizes on sea stars' prey-size preference, feeding rate, and prey tissue consumption. We found that preferred prey size increased with sea star size. Pisaster consumption rate (mussels consumed per day) and tissue intake rate (grams of tissue consumed per day) also increased with sea star size. Pisaster consumption rate, but not tissue intake rate, decreased with increasing mussel size. Juvenile sea stars preferred the most profitable prey sizes-that is, those that maximized tissue consumed per unit handling time. When adult sea stars were offered larger, more profitable mussels, tissue intake rates (grams per day) tended to increase, although this relationship was not statistically significant. Our results indicate that the Pisaster-Mytilus interaction depends on the sizes of both predator and prey, that predation rates are sensitive to even small changes in body size, and that shifts in size distributions may affect predator energetics and prey numbers differently depending on the factors that limit tissue consumption rates.

  2. Measuring the extent and effectiveness of protected areas as an indicator for meeting global biodiversity targets

    PubMed Central

    Chape, S; Harrison, J; Spalding, M; Lysenko, I

    2005-01-01

    There are now over 100 000 protected areas worldwide, covering over 12% of the Earth's land surface. These areas represent one of the most significant human resource use allocations on the planet. The importance of protected areas is reflected in their widely accepted role as an indicator for global targets and environmental assessments. However, measuring the number and extent of protected areas only provides a unidimensional indicator of political commitment to biodiversity conservation. Data on the geographic location and spatial extent of protected areas will not provide information on a key determinant for meeting global biodiversity targets: ‘effectiveness’ in conserving biodiversity. Although tools are being devised to assess management effectiveness, there is no globally accepted metric. Nevertheless, the numerical, spatial and geographic attributes of protected areas can be further enhanced by investigation of the biodiversity coverage of these protected areas, using species, habitats or biogeographic classifications. This paper reviews the current global extent of protected areas in terms of geopolitical and habitat coverage, and considers their value as a global indicator of conservation action or response. The paper discusses the role of the World Database on Protected Areas and collection and quality control issues, and identifies areas for improvement, including how conservation effectiveness indicators may be included in the database to improve the value of protected areas data as an indicator for meeting global biodiversity targets. PMID:15814356

  3. Deterministic and Stochastic Analysis of a Prey-Dependent Predator-Prey System

    ERIC Educational Resources Information Center

    Maiti, Alakes; Samanta, G. P.

    2005-01-01

    This paper reports on studies of the deterministic and stochastic behaviours of a predator-prey system with prey-dependent response function. The first part of the paper deals with the deterministic analysis of uniform boundedness, permanence, stability and bifurcation. In the second part the reproductive and mortality factors of the prey and…

  4. Prey Carrying Capacity Modulates the Effect of Predation on Prey Diversity.

    PubMed

    Socolar, Jacob; Washburne, Alex

    2015-09-01

    Understanding the role of predation in regulating prey diversity is a major goal in ecology, with profound consequences for community dynamics, ecosystem structure, and conservation practice. Deterministic differential equation models predict that some predation regimes, such as prey-switching predation, should promote prey coexistence and increase prey diversity. However, such models do not capture stochastic population fluctuations that are ubiquitous in empirical study sites and nature reserves. In this article, we examine the effects of prey-switching predation on the species richness of prey communities with demographic noise. We show that in finite, discrete prey populations, the ability of prey-switching predation to promote diversity depends on the carrying capacity of the prey community and the richness of the source pool for prey. Identical predation regimes may have opposite effects on prey diversity depending on the size and productivity of the habitat or the metacommunity richness. Statistical properties of the fluctuations of prey populations determine the effect of stabilizing mechanisms on species richness. We discuss the implications of this result for empirical studies of predation in small study areas and for the management of small nature reserves.

  5. "Prey Play": Learning about Predators and Prey through an Interactive, Role-Play Game

    ERIC Educational Resources Information Center

    Deaton, Cynthia C. M.; Dodd, Kristen; Drennon, Katherine; Nagle, Jack

    2012-01-01

    "Prey Play" is an interactive role-play activity that provides fifth-grade students with opportunities to examine predator-prey interactions. This four-part, role-play activity allows students to take on the role of a predator and prey as they reflect on the behaviors animals exhibit as they collect food and interact with one another, as well as…

  6. Controllability and Optimal Harvesting of a Prey-Predator Model Incorporating a Prey Refuge

    ERIC Educational Resources Information Center

    Kar, Tapan Kumar

    2006-01-01

    This paper deals with a prey-predator model incorporating a prey refuge and harvesting of the predator species. A mathematical analysis shows that prey refuge plays a crucial role for the survival of the species and that the harvesting effort on the predator may be used as a control to prevent the cyclic behaviour of the system. The optimal…

  7. The Many Faces of Fear: Comparing the Pathways and Impacts of Nonconsumptive Predator Effects on Prey Populations

    PubMed Central

    Preisser, Evan L.; Bolnick, Daniel I.

    2008-01-01

    Background Most ecological models assume that predator and prey populations interact solely through consumption: predators reduce prey densities by killing and consuming individual prey. However, predators can also reduce prey densities by forcing prey to adopt costly defensive strategies. Methodology/Principal Findings We build on a simple Lotka-Volterra predator-prey model to provide a heuristic tool for distinguishing between the demographic effects of consumption (consumptive effects) and of anti-predator defenses (nonconsumptive effects), and for distinguishing among the multiple mechanisms by which anti-predator defenses might reduce prey population growth rates. We illustrate these alternative pathways for nonconsumptive effects with selected empirical examples, and use a meta-analysis of published literature to estimate the mean effect size of each pathway. Overall, predation risk tends to have a much larger impact on prey foraging behavior than measures of growth, survivorship, or fecundity. Conclusions/Significance While our model provides a concise framework for understanding the many potential NCE pathways and their relationships to each other, our results confirm empirical research showing that prey are able to partially compensate for changes in energy income, mitigating the fitness effects of defensive changes in time budgets. Distinguishing the many facets of nonconsumptive effects raises some novel questions, and will help guide both empirical and theoretical studies of how predation risk affects prey dynamics. PMID:18560575

  8. Cats protecting birds revisited.

    PubMed

    Fan, Meng; Kuang, Yang; Feng, Zhilan

    2005-09-01

    In this paper, we revisit the dynamical interaction among prey (bird), mesopredator (rat), and superpredator (cat) discussed in [Courchamp, F., Langlais, M., Sugihara, G., 1999. Cats protecting birds: modelling the mesopredator release effect. Journal of Animal Ecology 68, 282-292]. First, we develop a prey-mesopredator-superpredator (i.e., bird-rat-cat, briefly, BRC) model, where the predator's functional responses are derived based on the classical Holling's time budget arguments. Our BRC model overcomes several model construction problems in Courchamp et al. (1999), and admits richer, reasonable and realistic dynamics. We explore the possible control strategies to save or restore the bird by controlling or eliminating the rat or the cat when the bird is endangered. We establish the existence of two types of mesopredator release phenomena: severe mesopredator release, where once superpredators are suppressed, a burst of mesopredators follows which leads their shared prey to extinction; and mild mesopredator release, where the mesopredator release could assert more negative impact on the endemic prey but does not lead the endemic prey to extinction. A sharp sufficient criterion is established for the occurrence of severe mesopredator release. We also show that, in a prey-mesopredator-superpredator trophic food web, eradication of introduced superpredators such as feral domestic cats in the BRC model, is not always the best solution to protect endemic insular prey. The presence of a superpredator may have a beneficial effect in such systems. PMID:15998496

  9. Infrared tomographic PIV and 3D motion tracking system applied to aquatic predator-prey interaction

    NASA Astrophysics Data System (ADS)

    Adhikari, Deepak; Longmire, Ellen K.

    2013-02-01

    Infrared tomographic PIV and 3D motion tracking are combined to measure evolving volumetric velocity fields and organism trajectories during aquatic predator-prey interactions. The technique was used to study zebrafish foraging on both non-evasive and evasive prey species. Measurement volumes of 22.5 mm × 10.5 mm × 12 mm were reconstructed from images captured on a set of four high-speed cameras. To obtain accurate fluid velocity vectors within each volume, fish were first masked out using an automated visual hull method. Fish and prey locations were identified independently from the same image sets and tracked separately within the measurement volume. Experiments demonstrated that fish were not influenced by the infrared laser illumination or the tracer particles. Results showed that the zebrafish used different strategies, suction and ram feeding, for successful capture of non-evasive and evasive prey, respectively. The two strategies yielded different variations in fluid velocity between the fish mouth and the prey. In general, the results suggest that the local flow field, the direction of prey locomotion with respect to the predator and the relative accelerations and speeds of the predator and prey may all be significant in determining predation success.

  10. Patterns of prey selection by wolves in Denali National Park, Alaska

    USGS Publications Warehouse

    Mech, L.D.; Meier, T.J.; Burch, J.W.; Adams, L.G.; Carbyn, L.N.; Fritts, S.H.; Seip, D.R.

    1995-01-01

    The patterns of selection by wolves (Canis lupus) preying on moose (Alces alces), caribou (Rangifer tarandus), and Dall sheep (Ovis dalli) in Denali National Park and Preserve, Alaska were studied from 1986 through early 1992. Wolves and their prey are legally protected or relatively unharvested in most of the area, and wolf numbers doubled during the study. Based on remains of 294 moose, 225 caribou, and 63 sheep, wolves killed calves and old adults disproportionately, and individuals with low marrow fat, jaw necrosis, or arthritis. Seasonal trends in proportions of various species, ages, and sex of kills were found. During the winters following winters of deep snowfalls, wolves greatly increased the proportion of caribou cows and calves taken. We conclude that in a natural system, wolves can survive on vulnerable prey even during moderate weather, and when snowfall exceeds average, they can respond by switching to newly vulnerable prey and greatly increasing their numbers.

  11. Leakage current measurement of protective equipment insulating materials used in electrical installations

    NASA Astrophysics Data System (ADS)

    Buică, G.; Dobra, R.; Păsculescu, D.; Tătar, A.

    2016-06-01

    This research describes the behaviour of equipment and safety devices during use in extreme environmental conditions, in order to establish the technical conditions and additional health and safety requirements during operation, to ensure the health and safety of users, regardless of conditions and working environment in which they are use. The studies have been conducted both on new equipment and means of protection used in electrical installations. There has been evaluated protective equipment made of insulating rubber, reinforced fiberglass or PVC. They have been followed the technical characteristics and protection against electric shock by measuring the leakage current of different insulating materials.

  12. A Sensory-Driven Trade-Off between Coordinated Motion in Social Prey and a Predator’s Visual Confusion

    PubMed Central

    Lemasson, Bertrand H.; Tanner, Colby J.; Dimperio, Eric

    2016-01-01

    Social animals are capable of enhancing their awareness by paying attention to their neighbors, and prey found in groups can also confuse their predators. Both sides of these sensory benefits have long been appreciated, yet less is known of how the perception of events from the perspectives of both prey and predator can interact to influence their encounters. Here we examined how a visual sensory mechanism impacts the collective motion of prey and, subsequently, how their resulting movements influenced predator confusion and capture ability. We presented virtual prey to human players in a targeting game and measured the speed and accuracy with which participants caught designated prey. As prey paid more attention to neighbor movements their collective coordination increased, yet increases in prey coordination were positively associated with increases in the speed and accuracy of attacks. However, while attack speed was unaffected by the initial state of the prey, accuracy dropped significantly if the prey were already organized at the start of the attack, rather than in the process of self-organizing. By repeating attack scenarios and masking the targeted prey’s neighbors we were able to visually isolate them and conclusively demonstrate how visual confusion impacted capture ability. Delays in capture caused by decreased coordination amongst the prey depended upon the collection motion of neighboring prey, while it was primarily the motion of the targets themselves that determined capture accuracy. Interestingly, while a complete loss of coordination in the prey (e.g., a flash expansion) caused the greatest delay in capture, such behavior had little effect on capture accuracy. Lastly, while increases in collective coordination in prey enhanced personal risk, traveling in coordinated groups was still better than appearing alone. These findings demonstrate a trade-off between the sensory mechanisms that can enhance the collective properties that emerge in social

  13. Prey-Induced Swimming Dynamics Changes among Predatory Algae

    NASA Astrophysics Data System (ADS)

    Katz, J.; Sheng, J.; Malkiel, E.; Adolf, J.; Place, A.; Belas, R.

    2007-11-01

    High speed, cinematic digital holographic microscopy allows us to track thousands of microorganisms over a volume with substantial depth without loss of resolution. This technique enables us, for the first time, to examine, measure and characterize the swimming dynamics of microorganisms located within dense suspensions. The present experiments examine dense populations of predatory algae, K. veneficum and P. piscicida, prior to and after introducing prey. Swimming dynamics are characterized by radius and pitch of helical swimming trajectories, by translational and angular velocity, and their velocity spectra. K. veneficum moves in both left and right hand helices, while P. piscicida swims only in right hand helices. The radii increase with increasing velocity for both cases. Presented with its prey, K. veneficum reduces its velocity, radius and pitch, but increases its angular velocity. Conversely, P. piscicida increases its speed, radius and angular velocity. Power spectra of velocity reveal differences between scales of vertical velocity and those of horizontal components. Power spectra of velocity component aligned with the helix centerline reveals a shift in K. veneficum's swimming strategy from almost random-walk to a levy-walk as prey is introduced. P. piscicida always displays clear preference towards levy-walk, but spectral slope increases as prey is introduced.

  14. Not So Fast: Swimming Behavior of Sailfish during Predator-Prey Interactions using High-Speed Video and Accelerometry.

    PubMed

    Marras, Stefano; Noda, Takuji; Steffensen, John F; Svendsen, Morten B S; Krause, Jens; Wilson, Alexander D M; Kurvers, Ralf H J M; Herbert-Read, James; Boswell, Kevin M; Domenici, Paolo

    2015-10-01

    Billfishes are considered among the fastest swimmers in the oceans. Despite early estimates of extremely high speeds, more recent work showed that these predators (e.g., blue marlin) spend most of their time swimming slowly, rarely exceeding 2 m s(-1). Predator-prey interactions provide a context within which one may expect maximal speeds both by predators and prey. Beyond speed, however, an important component determining the outcome of predator-prey encounters is unsteady swimming (i.e., turning and accelerating). Although large predators are faster than their small prey, the latter show higher performance in unsteady swimming. To contrast the evading behaviors of their highly maneuverable prey, sailfish and other large aquatic predators possess morphological adaptations, such as elongated bills, which can be moved more rapidly than the whole body itself, facilitating capture of the prey. Therefore, it is an open question whether such supposedly very fast swimmers do use high-speed bursts when feeding on evasive prey, in addition to using their bill for slashing prey. Here, we measured the swimming behavior of sailfish by using high-frequency accelerometry and high-speed video observations during predator-prey interactions. These measurements allowed analyses of tail beat frequencies to estimate swimming speeds. Our results suggest that sailfish burst at speeds of about 7 m s(-1) and do not exceed swimming speeds of 10 m s(-1) during predator-prey interactions. These speeds are much lower than previous estimates. In addition, the oscillations of the bill during swimming with, and without, extension of the dorsal fin (i.e., the sail) were measured. We suggest that extension of the dorsal fin may allow sailfish to improve the control of the bill and minimize its yaw, hence preventing disturbance of the prey. Therefore, sailfish, like other large predators, may rely mainly on accuracy of movement and the use of the extensions of their bodies, rather than resorting

  15. Seasonal variability in otariid energetics: implications for the effects of predators on localized prey resources.

    PubMed

    Williams, Terrie M; Rutishauser, M; Long, B; Fink, T; Gafney, J; Mostman-Liwanag, H; Casper, D

    2007-01-01

    Otariids, like other wild mammals, contend with a wide variety of energetic demands across seasons. However, due to the cryptic behaviors of this marine group, few studies have been able to examine longitudinal energetic costs or the potential impact of these costs on seasonal or annual prey requirements. Here we evaluated the changes in energy demand and intake of female California sea lions (Zalophus californianus) during reproductive (n=2 sea lions) and nonreproductive (n=3) periods. Monthly measurements included resting metabolic rate, blood hormone levels, body condition (blubber thickness and body mass), and caloric intake for adult sea lions throughout molting, late pregnancy, lactation, and postweaning. We found that maintenance energy demands decreased from 32.0 to 23.1 MJ d(-1) before pupping, remaining stable at 19.4+/-0.6 MJ d(-1) during lactation and postweaning. Energy intake rates to meet these demands showed marked changes with activity level and the reproductive cycle, reaching a peak intake of 3.6 times baseline levels during lactation. Translating this into prey demands, we find that 20,000 reproductively active females on San Nicolas Island rookeries would maximally require 4,950 metric tons of Pacific whiting during a month of the breeding season. This localized impact is reduced significantly with postbreeding dispersal and demonstrates the importance of considering spatial and temporal factors driving the energetic requirements of predators when designing marine protected areas.

  16. Immune protection factors of chemical sunscreens measured in the local contact hypersensitivity model in humans.

    PubMed

    Wolf, Peter; Hoffmann, Christine; Quehenberger, Franz; Grinschgl, Stephan; Kerl, Helmut

    2003-11-01

    We conducted a randomized trial designed to calculate human in vivo immune protection factors of two sunscreen preparations in a model of ultraviolet-induced local suppression of the induction of contact hypersensitivity to 2,4-dinitrochlorobenzene. Seventy-five male subjects were exposed in a multistage study to multiples of their individual minimal erythema dose of solar-simulated ultraviolet radiation with or without protection by an ultraviolet B sunscreen (sun protection factor 5.2) or a broad-spectrum ultraviolet A + B sunscreen (sun protection factor 6.2). After 24 h subjects were sensitized with 50 microL of 0.0625% 2,4-dinitrochlorobenzene on a nonirradiated or ultraviolet-irradiated field on the buttock that was unprotected or protected by sunscreen. Three weeks after sensitization the subjects were challenged with varying concentrations of 2,4-dinitrochlorobenzene on their upper inner arm, and the contact hypersensitivity response was determined at 48 and 72 h based on a semiquantitative clinical score, contact hypersensitivity lesion diameters, and dermal skin edema measurement by 20 MHz ultrasound. The 50% immunosuppressive dose ranged from 0.63 to 0.79 minimal erythema dose, depending on the endpoint parameter. Both sunscreens offered significant immunoprotection (p = 0.014-0.002) and their immune protection factor ranged from 4.5 to 5.8 (ultraviolet B sunscreen) and from 7.7 to 11 (ultraviolet A + B sunscreen). The immune protection factor of the ultraviolet B sunscreen was similar to the sun protection factor (5.2), whereas the sunscreen with broad-spectrum ultraviolet A + B protection exhibited better immunoprotective capacity than predicted from the sun protection factor. PMID:14708610

  17. Prey availability influences the ontogeny and timing of chemoreception-based prey shifting in the striped crayfish snake, Regina alleni.

    PubMed

    Waters, R Mark; Burghardt, Gordon M

    2013-02-01

    Striped crayfish snakes (Regina alleni) undergo a dietary shift from dragonfly larvae to crayfish during ontogeny. Godley (1980) suggested that this shift is attributable to crayfish availability rather than an initial preference for dragonfly larvae. We experimentally tested this hypothesis by measuring the chemosensory response of newborn snakes to prey odors at 2 ages and also after they were fed on either dragonfly larvae or crayfish. The results show that R. alleni respond equally to dragonfly larvae, hard crayfish, and soft crayfish before feeding experience. We also show that the maintenance of this preference over fish and control stimuli is subsequently determined by the prey type encountered, through an unusual interaction. Snakes fed dragonfly larvae increased their chemosensory response to both dragonfly larvae and crayfish, whereas snakes fed crayfish increased their response only to crayfish. Our study demonstrates that innate chemosensory responses to prey can be modified by prey availability and that they do not necessarily result from maturation alone. Such plasticity has adaptive value to newborn animals that must fend for themselves from birth and respond to changing environmental conditions.

  18. Protecting tripartite entanglement in non-Markovian environments via quantum partially collapsing measurements

    NASA Astrophysics Data System (ADS)

    Ding, Zhi-Yong; He, Juan; Ye, Liu

    2016-08-01

    In this paper, the dynamics of tripartite entanglement via π -tangle in independent non-Markovian environments is investigated. The results indicate that the π -tangle vanishes periodically as decoherence time increases with a damping of its revival amplitude due to the memory of the non-Markovian environments. In addition, we present a scheme to protect entanglement of W state from non-Markovian environments by means of the quantum partially collapsing measurements. It is worth mentioning that our scheme is a successful protection for the tripartite quantum system and the effect is better for the larger measurement strength, while the stronger decoherence suppression induces smaller success probability.

  19. Cryptic differences in colour among Müllerian mimics: how can the visual capacities of predators and prey shape the evolution of wing colours?

    PubMed

    Llaurens, V; Joron, M; Théry, M

    2014-03-01

    Antagonistic interactions between predators and prey often lead to co-evolution. In the case of toxic prey, aposematic colours act as warning signals for predators and play a protective role. Evolutionary convergence in colour patterns among toxic prey evolves due to positive density-dependent selection and the benefits of mutual resemblance in spreading the mortality cost of educating predators over a larger prey assemblage. Comimetic species evolve highly similar colour patterns, but such convergence may interfere with intraspecific signalling and recognition in the prey community, especially for species involved in polymorphic mimicry. Using spectrophotometry measures, we investigated the variation in wing coloration among comimetic butterflies from distantly related lineages. We focused on seven morphs of the polymorphic species Heliconius numata and the seven corresponding comimetic species from the genus Melinaea. Significant differences in the yellow, orange and black patches of the wing were detected between genera. Perceptions of these cryptic differences by bird and butterfly observers were then estimated using models of animal vision based on physiological data. Our results showed that the most strikingly perceived differences were obtained for the contrast of yellow against a black background. The capacity to discriminate between comimetic genera based on this colour contrast was also evaluated to be higher for butterflies than for birds, suggesting that this variation in colour, likely undetectable to birds, might be used by butterflies for distinguishing mating partners without losing the benefits of mimicry. The evolution of wing colour in mimetic butterflies might thus be shaped by the opposite selective pressures exerted by predation and species recognition.

  20. Cryptic differences in colour among Müllerian mimics: how can the visual capacities of predators and prey shape the evolution of wing colours?

    PubMed

    Llaurens, V; Joron, M; Théry, M

    2014-03-01

    Antagonistic interactions between predators and prey often lead to co-evolution. In the case of toxic prey, aposematic colours act as warning signals for predators and play a protective role. Evolutionary convergence in colour patterns among toxic prey evolves due to positive density-dependent selection and the benefits of mutual resemblance in spreading the mortality cost of educating predators over a larger prey assemblage. Comimetic species evolve highly similar colour patterns, but such convergence may interfere with intraspecific signalling and recognition in the prey community, especially for species involved in polymorphic mimicry. Using spectrophotometry measures, we investigated the variation in wing coloration among comimetic butterflies from distantly related lineages. We focused on seven morphs of the polymorphic species Heliconius numata and the seven corresponding comimetic species from the genus Melinaea. Significant differences in the yellow, orange and black patches of the wing were detected between genera. Perceptions of these cryptic differences by bird and butterfly observers were then estimated using models of animal vision based on physiological data. Our results showed that the most strikingly perceived differences were obtained for the contrast of yellow against a black background. The capacity to discriminate between comimetic genera based on this colour contrast was also evaluated to be higher for butterflies than for birds, suggesting that this variation in colour, likely undetectable to birds, might be used by butterflies for distinguishing mating partners without losing the benefits of mimicry. The evolution of wing colour in mimetic butterflies might thus be shaped by the opposite selective pressures exerted by predation and species recognition. PMID:24444083

  1. Protecting a quantum state from environmental noise by an incompatible finite-time measurement

    SciTech Connect

    Brasil, Carlos Alexandre; Castro, L. A. de; Napolitano, R. d. J.

    2011-08-15

    We show that measurements of finite duration performed on an open two-state system can protect the initial state from a phase-noisy environment, provided the measured observable does not commute with the perturbing interaction. When the measured observable commutes with the environmental interaction, the finite-duration measurement accelerates the rate of decoherence induced by the phase noise. For the description of the measurement of an observable that is incompatible with the interaction between system and environment, we have found an approximate analytical expression, valid at zero temperature and weak coupling with the measuring device. We have tested the validity of the analytical predictions against an exact numerical approach, based on the superoperator-splitting method, that confirms the protection of the initial state of the system. When the coupling between the system and the measuring apparatus increases beyond the range of validity of the analytical approximation, the initial state is still protected by the finite-time measurement, according with the exact numerical calculations.

  2. National measures under the chemical weapons convention to protect confidential business information and compensate for its loss

    SciTech Connect

    Tanzman, E.A.; Kellman, B.

    1995-07-01

    This report contains a discussion presented at the Regional Seminar on the National Authority and the Chemical Weapons Convention. Measures to protect confidential business information and compensation for information which has not been sufficiently protected is discussed.

  3. Fluorescent prey traps in carnivorous plants.

    PubMed

    Kurup, R; Johnson, A J; Sankar, S; Hussain, A A; Sathish Kumar, C; Sabulal, B

    2013-05-01

    Carnivorous plants acquire most of their nutrients by capturing ants, insects and other arthropods through their leaf-evolved biological traps. So far, the best-known attractants in carnivorous prey traps are nectar, colour and olfactory cues. Here, fresh prey traps of 14 Nepenthes, five Sarracenia, five Drosera, two Pinguicula species/hybrids, Dionaea muscipula and Utricularia stellaris were scanned at UV 366 nm. Fluorescence emissions of major isolates of fresh Nepenthes khasiana pitcher peristomes were recorded at an excitation wavelength of 366 nm. N. khasiana field pitcher peristomes were masked by its slippery zone extract, and prey capture rates were compared with control pitchers. We found the existence of distinct blue fluorescence emissions at the capture spots of Nepenthes, Sarracenia and Dionaea prey traps at UV 366 nm. These alluring blue emissions gradually developed with the growth of the prey traps and diminished towards their death. On excitation at 366 nm, N. khasiana peristome 3:1 CHCl3–MeOH extract and its two major blue bands showed strong fluorescence emissions at 430–480 nm. Masking of blue emissions on peristomes drastically reduced prey capture in N. khasiana pitchers. We propose these molecular emissions as a critical factor attracting arthropods and other visitors to these carnivorous traps. Drosera, Pinguicula and Utricularia prey traps showed only red chlorophyll emissions at 366 nm.

  4. Investigation of Stinson Beach Park storm damage and evaluation of alternative shore protection measures

    SciTech Connect

    Ecker, R.M.; Whelan, G.

    1984-07-01

    An investigation was made of storm damage during the winter of 1982-83 to the National Park Service's Stinson Beach Park. The investigation included an assessment of the storm damage, evaluation of physical processes contributing to the damage, subsequent beach recovery, and the feasibility of implementing shoreline protection measure to reduce future risk. During the winter of 1982-83, the beach was almost completely denuded of sand, wave overwash damaged the foredune, vegetation on the foredune was destroyed, and backshore flooding occurred. Two structures and a parking lot were endangered as the shoreline receded. Subsequent recovery of the park beach was rapid. By January 1982 sand had moved back onshore and a beach berm was beginning to reform. The foredune and dune vegetation received the only permanent damage. Four shoreline protection alternatives were evaluated. These include no action, dune development/enhancement, construction of a rock riprap revetment, and offshore installation of artificial seaweed. The first costs (estimated costs, excluding maintenance) range from about $90,000 to $475,000. The least-cost protection measure is riprap revetment, which protects the two structures and parking lot endangered during the 1982-83 winter storms. Construction of a foredune along the entire park beach is the highest cost protection measure. If no shore protection action measures are implemented, wave overwash of the foredune can be expected to occur on the average of every 2 to 3 years, and beach degradation, similar to that during the 1982-83 winter, can be expected to occur on the average of every 10 to 12 years. 12 references, 19 figures, 18 tables.

  5. Cheetahs, Acinonyx jubatus, balance turn capacity with pace when chasing prey.

    PubMed

    Wilson, John W; Mills, Michael G L; Wilson, Rory P; Peters, Gerrit; Mills, Margaret E J; Speakman, John R; Durant, Sarah M; Bennett, Nigel C; Marks, Nikki J; Scantlebury, Michael

    2013-10-23

    Predator-prey interactions are fundamental in the evolution and structure of ecological communities. Our understanding, however, of the strategies used in pursuit and evasion remains limited. Here, we report on the hunting dynamics of the world's fastest land animal, the cheetah, Acinonyx jubatus. Using miniaturized data loggers, we recorded fine-scale movement, speed and acceleration of free-ranging cheetahs to measure how hunting dynamics relate to chasing different sized prey. Cheetahs attained hunting speeds of up to 18.94 m s(-1) and accelerated up to 7.5 m s(-2) with greatest angular velocities achieved during the terminal phase of the hunt. The interplay between forward and lateral acceleration during chases showed that the total forces involved in speed changes and turning were approximately constant over time but varied with prey type. Thus, rather than a simple maximum speed chase, cheetahs first accelerate to decrease the distance to their prey, before reducing speed 5-8 s from the end of the hunt, so as to facilitate rapid turns to match prey escape tactics, varying the precise strategy according to prey species. Predator and prey thus pit a fine balance of speed against manoeuvring capability in a race for survival.

  6. Musculoskeletal anatomy of the Eurasian lynx, Lynx lynx (Carnivora: Felidae) forelimb: Adaptations to capture large prey?

    PubMed

    Viranta, Suvi; Lommi, Hanna; Holmala, Katja; Laakkonen, Juha

    2016-06-01

    Mammalian carnivores adhere to two different feeding strategies relative to their body masses. Large carnivores prey on animals that are the same size or larger than themselves, whereas small carnivores prey on smaller vertebrates and invertebrates. The Eurasian lynx (Lynx lynx) falls in between these two categories. Lynx descend from larger forms that were probably large prey specialists, but during the Pleistocene became predators of small prey. The modern Eurasian lynx may be an evolutionary reversal toward specializing in large prey again. We hypothesized that the musculoskeletal anatomy of lynx should show traits for catching large prey. To test our hypothesis, we dissected the forelimb muscles of six Eurasian lynx individuals and compared our findings to results published for other felids. We measured the bones and compared their dimensions to the published material. Our material displayed a well-developed pectoral girdle musculature with some uniquely extensive muscle attachments. The upper arm musculature resembled that of the pantherine felids and probably the extinct sabertooths, and also the muscles responsible for supination and pronation were similar to those in large cats. The muscles controlling the pollex were well-developed. However, skeletal indices were similar to those of small prey predators. Our findings show that lynx possess the topographic pattern of muscle origin and insertion like in large felids. J. Morphol. 277:753-765, 2016. © 2016 Wiley Periodicals, Inc. PMID:26997516

  7. Cheetahs, Acinonyx jubatus, balance turn capacity with pace when chasing prey

    PubMed Central

    Wilson, John W.; Mills, Michael G. L.; Wilson, Rory P.; Peters, Gerrit; Mills, Margaret E. J.; Speakman, John R.; Durant, Sarah M.; Bennett, Nigel C.; Marks, Nikki J.; Scantlebury, Michael

    2013-01-01

    Predator–prey interactions are fundamental in the evolution and structure of ecological communities. Our understanding, however, of the strategies used in pursuit and evasion remains limited. Here, we report on the hunting dynamics of the world's fastest land animal, the cheetah, Acinonyx jubatus. Using miniaturized data loggers, we recorded fine-scale movement, speed and acceleration of free-ranging cheetahs to measure how hunting dynamics relate to chasing different sized prey. Cheetahs attained hunting speeds of up to 18.94 m s−1 and accelerated up to 7.5 m s−2 with greatest angular velocities achieved during the terminal phase of the hunt. The interplay between forward and lateral acceleration during chases showed that the total forces involved in speed changes and turning were approximately constant over time but varied with prey type. Thus, rather than a simple maximum speed chase, cheetahs first accelerate to decrease the distance to their prey, before reducing speed 5–8 s from the end of the hunt, so as to facilitate rapid turns to match prey escape tactics, varying the precise strategy according to prey species. Predator and prey thus pit a fine balance of speed against manoeuvring capability in a race for survival. PMID:24004493

  8. Musculoskeletal anatomy of the Eurasian lynx, Lynx lynx (Carnivora: Felidae) forelimb: Adaptations to capture large prey?

    PubMed

    Viranta, Suvi; Lommi, Hanna; Holmala, Katja; Laakkonen, Juha

    2016-06-01

    Mammalian carnivores adhere to two different feeding strategies relative to their body masses. Large carnivores prey on animals that are the same size or larger than themselves, whereas small carnivores prey on smaller vertebrates and invertebrates. The Eurasian lynx (Lynx lynx) falls in between these two categories. Lynx descend from larger forms that were probably large prey specialists, but during the Pleistocene became predators of small prey. The modern Eurasian lynx may be an evolutionary reversal toward specializing in large prey again. We hypothesized that the musculoskeletal anatomy of lynx should show traits for catching large prey. To test our hypothesis, we dissected the forelimb muscles of six Eurasian lynx individuals and compared our findings to results published for other felids. We measured the bones and compared their dimensions to the published material. Our material displayed a well-developed pectoral girdle musculature with some uniquely extensive muscle attachments. The upper arm musculature resembled that of the pantherine felids and probably the extinct sabertooths, and also the muscles responsible for supination and pronation were similar to those in large cats. The muscles controlling the pollex were well-developed. However, skeletal indices were similar to those of small prey predators. Our findings show that lynx possess the topographic pattern of muscle origin and insertion like in large felids. J. Morphol. 277:753-765, 2016. © 2016 Wiley Periodicals, Inc.

  9. Cheetahs, Acinonyx jubatus, balance turn capacity with pace when chasing prey.

    PubMed

    Wilson, John W; Mills, Michael G L; Wilson, Rory P; Peters, Gerrit; Mills, Margaret E J; Speakman, John R; Durant, Sarah M; Bennett, Nigel C; Marks, Nikki J; Scantlebury, Michael

    2013-10-23

    Predator-prey interactions are fundamental in the evolution and structure of ecological communities. Our understanding, however, of the strategies used in pursuit and evasion remains limited. Here, we report on the hunting dynamics of the world's fastest land animal, the cheetah, Acinonyx jubatus. Using miniaturized data loggers, we recorded fine-scale movement, speed and acceleration of free-ranging cheetahs to measure how hunting dynamics relate to chasing different sized prey. Cheetahs attained hunting speeds of up to 18.94 m s(-1) and accelerated up to 7.5 m s(-2) with greatest angular velocities achieved during the terminal phase of the hunt. The interplay between forward and lateral acceleration during chases showed that the total forces involved in speed changes and turning were approximately constant over time but varied with prey type. Thus, rather than a simple maximum speed chase, cheetahs first accelerate to decrease the distance to their prey, before reducing speed 5-8 s from the end of the hunt, so as to facilitate rapid turns to match prey escape tactics, varying the precise strategy according to prey species. Predator and prey thus pit a fine balance of speed against manoeuvring capability in a race for survival. PMID:24004493

  10. 43 CFR 3162.7 - Measurement, disposition, and protection of production.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 43 Public Lands: Interior 2 2012-10-01 2012-10-01 false Measurement, disposition, and protection of production. 3162.7 Section 3162.7 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) ONSHORE OIL AND GAS OPERATIONS Requirements for...

  11. 78 FR 55765 - Compensatory and Alternative Regulatory Measures for Nuclear Power Plant Fire Protection (CARMEN...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-11

    ... (78 FR 45573) a request for public comment on NUREG/CR-7135, ``Compensatory and Alternative Regulatory... COMMISSION Compensatory and Alternative Regulatory Measures for Nuclear Power Plant Fire Protection (CARMEN-FIRE) AGENCY: Nuclear Regulatory Commission. ACTION: Draft NUREG/CR, reopening of comment...

  12. Microbiological survey of birds of prey pellets.

    PubMed

    Dipineto, Ludovico; Bossa, Luigi Maria De Luca; Pace, Antonino; Russo, Tamara Pasqualina; Gargiulo, Antonio; Ciccarelli, Francesca; Raia, Pasquale; Caputo, Vincenzo; Fioretti, Alessandro

    2015-08-01

    A microbiological survey of 73 pellets collected from different birds of prey species housed at the Wildlife Rescue and Rehabilitation Center of Napoli (southern Italy) was performed. Pellets were analyzed by culture and biochemical methods as well as by serotyping and polymerase chain reaction. We isolated a wide range of bacteria some of them also pathogens for humans (i.e. Salmonella enterica serotype Typhimurium, Campylobacter coli, Escherichia coli O serogroups). This study highlights the potential role of birds of prey as asymptomatic carriers of pathogenic bacteria which could be disseminated in the environment not only through the birds of prey feces but also through their pellets.

  13. Microbiological survey of birds of prey pellets.

    PubMed

    Dipineto, Ludovico; Bossa, Luigi Maria De Luca; Pace, Antonino; Russo, Tamara Pasqualina; Gargiulo, Antonio; Ciccarelli, Francesca; Raia, Pasquale; Caputo, Vincenzo; Fioretti, Alessandro

    2015-08-01

    A microbiological survey of 73 pellets collected from different birds of prey species housed at the Wildlife Rescue and Rehabilitation Center of Napoli (southern Italy) was performed. Pellets were analyzed by culture and biochemical methods as well as by serotyping and polymerase chain reaction. We isolated a wide range of bacteria some of them also pathogens for humans (i.e. Salmonella enterica serotype Typhimurium, Campylobacter coli, Escherichia coli O serogroups). This study highlights the potential role of birds of prey as asymptomatic carriers of pathogenic bacteria which could be disseminated in the environment not only through the birds of prey feces but also through their pellets. PMID:26026881

  14. Ecoepidemics with Two Strains: Diseased Prey.

    NASA Astrophysics Data System (ADS)

    Elena, Elisa; Grammauro, Maria; Venturino, Ezio

    2011-09-01

    In this work we present a minimal model for an ecoepidemic situation with two diseases affecting the prey population. The main assumptions are the following ones. The predators recognize and hunt only the healthy prey. An infected prey of one strain becomes immune to the other one. The major finding shows that the two strains cannot simultaneously thrive in the system, contrary to the standard assumptions in epidemiology. But this rather unexpected and remarkable result, paralleling another one when the epidemics affects the predators, is most likely due to the assumptions made.

  15. Relative influence of prey mercury concentration, prey energy density and predator sex on sport fish mercury concentrations.

    PubMed

    Stacy, W L; Lepak, J M

    2012-10-15

    Mercury (Hg) bioaccumulation in aquatic food webs has created a human health concern for anglers who consume fish. Variability in sport fish Hg concentration adds to the uncertainty of the amount of fish an angler can safely consume, so predicting where variability arises is useful. We evaluated the relative influence of diet (prey Hg concentration and energy density) and sex on sport fish Hg concentrations using a bioenergetics approach. Our results indicated that sport fish diets (prey Hg concentration followed by energy density) were the most important factors for determining sport fish Hg concentration followed by sex. Although physiological and behavioral differences based on sex may lead to differences in gross growth efficiency, resulting in different Hg concentrations in male and female sport fish, evaluating the relative importance of these differences will require sex-specific parameterization of bioenergetics models. Our results support previous findings that knowledge of sport fish diets (prey Hg concentration followed by energy density) and sex could aid in the prediction of sport fish Hg concentrations. Thus, basic knowledge of system-specific food web structure could provide valuable information for developing sport fish consumption advisories to better protect anglers and their families from Hg contamination. PMID:22922134

  16. Effects of turbidity on the spontaneous and prey-searching activity of juvenile Atlantic cod (Gadus morhua).

    PubMed

    Meager, Justin J; Batty, Robert S

    2007-11-29

    Increasing turbidity in coastal waters in the North Atlantic and adjacent seas has raised concerns about impacts on Atlantic cod (Gadus morhua) using these areas as nurseries. A previous experiment (Meager et al. 2005 Can. J. Fish. Aquat. Sci. 62, 1978-1984) has shown that turbidity (up to 28 beam attenuation m-1) had little effect on the foraging rate of juvenile cod. Although this was attributed to cod using chemoreception in conjunction with vision to locate prey, foraging rates may also be maintained by increased activity. Higher activity, however, is energetically costly and may offset benefits from increased foraging return. We examined the effects of turbidity on prey searching and spontaneous activity of juvenile cod in the laboratory, by measuring activity with and without prey cues. Activity of juvenile cod was nonlinearly affected by turbidity and was lower at intermediate turbidity, regardless of the presence of prey odour. Activity increased over time when prey odour was present and decreased when absent, but the effects of prey odour were similar across all turbidity levels. Position in the tank was unaffected by turbidity or prey odour. Reduced activity at intermediate turbidities is likely to offset longer prey-search times. At high turbidity (greater than 17m-1), both longer prey-search times and higher activity indicate that increased energetic costs are probable.

  17. [Evaluation of the efficiency of Angara River water protection measures against pollution by petroleum products].

    PubMed

    Zabuga, G A; Katul'skiĭ, Iu N; Gorbunova, O V; Storozheva, L N

    2011-01-01

    The process installations and storage reservoirs of a petroleum refinery have leaks of petroleum products (PP) that pollute soil, underground waters, and eventually nearest water objects, by worsening their hygienic state. Environmental and economic assessments of the Angara River water protection system that is in operation at the petroleum refinery OAO "Angara Petroleum Company", which comprises well clusters, a gravel-filled trench, and a drainage system, have shown the high values of preventable relative natural and economic damages and other economic indicators. At the same time, comparison of the amount of PPs accumulated at the industrial site with their annual withdrawal has demonstrated a need for further development of a river protection system. Therefore the environmental protection system efficacy evaluated by the quality of goal attainment and by means of a matrix of algorithmized statements was 60% or 5 of 20 scores, which shows the necessity of special measures to protect Angara River waters. The elaboration and implementation of these measures associated with considerable expenditures make it possible not only to increase the environmental efficiency of water protection of the Angara River, but also to do the hygienic quality of water use in its related localities.

  18. Inferring predator behavior from attack rates on prey-replicas that differ in conspicuousness.

    PubMed

    Stuart, Yoel E; Dappen, Nathan; Losin, Neil

    2012-01-01

    Behavioral ecologists and evolutionary biologists have long studied how predators respond to prey items novel in color and pattern. Because a predatory response is influenced by both the predator's ability to detect the prey and a post-detection behavioral response, variation among prey types in conspicuousness may confound inference about post-prey-detection predator behavior. That is, a relatively high attack rate on a given prey type may result primarily from enhanced conspicuousness and not predators' direct preference for that prey. Few studies, however, account for such variation in conspicuousness. In a field experiment, we measured predation rates on clay replicas of two aposematic forms of the poison dart frog Dendrobates pumilio, one novel and one familiar, and two cryptic controls. To ask whether predators prefer or avoid a novel aposematic prey form independently of conspicuousness differences among replicas, we first modeled the visual system of a typical avian predator. Then, we used this model to estimate replica contrast against a leaf litter background to test whether variation in contrast alone could explain variation in predator attack rate. We found that absolute predation rates did not differ among color forms. Predation rates relative to conspicuousness did, however, deviate significantly from expectation, suggesting that predators do make post-detection decisions to avoid or attack a given prey type. The direction of this deviation from expectation, though, depended on assumptions we made about how avian predators discriminate objects from the visual background. Our results show that it is important to account for prey conspicuousness when investigating predator behavior and also that existing models of predator visual systems need to be refined. PMID:23119039

  19. Inferring Predator Behavior from Attack Rates on Prey-Replicas That Differ in Conspicuousness

    PubMed Central

    2012-01-01

    Behavioral ecologists and evolutionary biologists have long studied how predators respond to prey items novel in color and pattern. Because a predatory response is influenced by both the predator’s ability to detect the prey and a post-detection behavioral response, variation among prey types in conspicuousness may confound inference about post-prey-detection predator behavior. That is, a relatively high attack rate on a given prey type may result primarily from enhanced conspicuousness and not predators’ direct preference for that prey. Few studies, however, account for such variation in conspicuousness. In a field experiment, we measured predation rates on clay replicas of two aposematic forms of the poison dart frog Dendrobates pumilio, one novel and one familiar, and two cryptic controls. To ask whether predators prefer or avoid a novel aposematic prey form independently of conspicuousness differences among replicas, we first modeled the visual system of a typical avian predator. Then, we used this model to estimate replica contrast against a leaf litter background to test whether variation in contrast alone could explain variation in predator attack rate. We found that absolute predation rates did not differ among color forms. Predation rates relative to conspicuousness did, however, deviate significantly from expectation, suggesting that predators do make post-detection decisions to avoid or attack a given prey type. The direction of this deviation from expectation, though, depended on assumptions we made about how avian predators discriminate objects from the visual background. Our results show that it is important to account for prey conspicuousness when investigating predator behavior and also that existing models of predator visual systems need to be refined. PMID:23119039

  20. Relative Preference and Localized Food Affect Predator Space Use and Consumption of Incidental Prey.

    PubMed

    Schartel, Tyler E; Schauber, Eric M

    2016-01-01

    Abundant, localized foods can concentrate predators and their foraging efforts, thus altering both the spatial distribution of predation risk and predator preferences for prey that are encountered incidentally. However, few investigations have quantified the spatial scale over which localized foods affect predator foraging behavior and consumption of incidental prey. In spring 2010, we experimentally tested how point-source foods altered how generalist predators (white-footed mice, Peromyscus leucopus) utilized space and depredated two incidental prey items: almonds (Prunus dulcis; highly profitable) and maple seeds (Acer saccharum; less profitable). We estimated mouse population densities with trapping webs, quantified mouse consumption rates of these incidental prey items, and measured local mouse activity with track plates. We predicted that 1) mouse activity would be elevated near full feeders, but depressed at intermediate distances from the feeder, 2) consumption of both incidental prey would be high near feeders providing less-preferred food and, 3) consumption of incidental prey would be contingent on predator preference for prey relative to feeders providing more-preferred food. Mouse densities increased significantly from pre- to post-experiment. Mean mouse activity was unexpectedly greatest in control treatments, particularly <15 m from the control (empty) feeder. Feeders with highly preferred food (sunflower seeds) created localized refuges for incidental prey at intermediate distances (15 to 25m) from the feeder. Feeders with less-preferred food (corn) generated localized high risk for highly preferred almonds <10 m of the feeder. Our findings highlight the contingent but predictable effects of locally abundant food on risk experienced by incidental prey, which can be positive or negative depending on both spatial proximity and relative preference.

  1. Relative Preference and Localized Food Affect Predator Space Use and Consumption of Incidental Prey.

    PubMed

    Schartel, Tyler E; Schauber, Eric M

    2016-01-01

    Abundant, localized foods can concentrate predators and their foraging efforts, thus altering both the spatial distribution of predation risk and predator preferences for prey that are encountered incidentally. However, few investigations have quantified the spatial scale over which localized foods affect predator foraging behavior and consumption of incidental prey. In spring 2010, we experimentally tested how point-source foods altered how generalist predators (white-footed mice, Peromyscus leucopus) utilized space and depredated two incidental prey items: almonds (Prunus dulcis; highly profitable) and maple seeds (Acer saccharum; less profitable). We estimated mouse population densities with trapping webs, quantified mouse consumption rates of these incidental prey items, and measured local mouse activity with track plates. We predicted that 1) mouse activity would be elevated near full feeders, but depressed at intermediate distances from the feeder, 2) consumption of both incidental prey would be high near feeders providing less-preferred food and, 3) consumption of incidental prey would be contingent on predator preference for prey relative to feeders providing more-preferred food. Mouse densities increased significantly from pre- to post-experiment. Mean mouse activity was unexpectedly greatest in control treatments, particularly <15 m from the control (empty) feeder. Feeders with highly preferred food (sunflower seeds) created localized refuges for incidental prey at intermediate distances (15 to 25m) from the feeder. Feeders with less-preferred food (corn) generated localized high risk for highly preferred almonds <10 m of the feeder. Our findings highlight the contingent but predictable effects of locally abundant food on risk experienced by incidental prey, which can be positive or negative depending on both spatial proximity and relative preference. PMID:26978659

  2. Nitrogen deposition and prey nitrogen uptake control the nutrition of the carnivorous plant Drosera rotundifolia.

    PubMed

    Millett, J; Foot, G W; Svensson, B M

    2015-04-15

    Nitrogen (N) deposition has important negative impacts on natural and semi-natural ecosystems, impacting on biotic interactions across trophic levels. Low-nutrient systems are particularly sensitive to changes in N inputs and are therefore more vulnerable to N deposition. Carnivorous plants are often part of these ecosystems partly because of the additional nutrients obtained from prey. We studied the impact of N deposition on the nutrition of the carnivorous plant Drosera rotundifolia growing on 16 ombrotrophic bogs across Europe. We measured tissue N, phosphorus (P) and potassium (K) concentrations and prey and root N uptake using a natural abundance stable isotope approach. Our aim was to test the impact of N deposition on D. rotundifolia prey and root N uptake, and nutrient stoichiometry. D. rotundifolia root N uptake was strongly affected by N deposition, possibly resulting in reduced N limitation. The contribution of prey N to the N contained in D. rotundifolia ranged from 20 to 60%. N deposition reduced the maximum amount of N derived from prey, but this varied below this maximum. D. rotundifolia tissue N concentrations were a product of both root N availability and prey N uptake. Increased prey N uptake was correlated with increased tissue P concentrations indicating uptake of P from prey. N deposition therefore reduced the strength of a carnivorous plant-prey interaction, resulting in a reduction in nutrient transfer between trophic levels. We suggest that N deposition has a negative impact on D. rotundifolia and that responses to N deposition might be strongly site specific. PMID:25655989

  3. Relative Preference and Localized Food Affect Predator Space Use and Consumption of Incidental Prey

    PubMed Central

    Schartel, Tyler E.; Schauber, Eric M.

    2016-01-01

    Abundant, localized foods can concentrate predators and their foraging efforts, thus altering both the spatial distribution of predation risk and predator preferences for prey that are encountered incidentally. However, few investigations have quantified the spatial scale over which localized foods affect predator foraging behavior and consumption of incidental prey. In spring 2010, we experimentally tested how point-source foods altered how generalist predators (white-footed mice, Peromyscus leucopus) utilized space and depredated two incidental prey items: almonds (Prunus dulcis; highly profitable) and maple seeds (Acer saccharum; less profitable). We estimated mouse population densities with trapping webs, quantified mouse consumption rates of these incidental prey items, and measured local mouse activity with track plates. We predicted that 1) mouse activity would be elevated near full feeders, but depressed at intermediate distances from the feeder, 2) consumption of both incidental prey would be high near feeders providing less-preferred food and, 3) consumption of incidental prey would be contingent on predator preference for prey relative to feeders providing more-preferred food. Mouse densities increased significantly from pre- to post-experiment. Mean mouse activity was unexpectedly greatest in control treatments, particularly <15 m from the control (empty) feeder. Feeders with highly preferred food (sunflower seeds) created localized refuges for incidental prey at intermediate distances (15 to 25m) from the feeder. Feeders with less-preferred food (corn) generated localized high risk for highly preferred almonds <10 m of the feeder. Our findings highlight the contingent but predictable effects of locally abundant food on risk experienced by incidental prey, which can be positive or negative depending on both spatial proximity and relative preference. PMID:26978659

  4. Predators' decisions to eat defended prey depend on the size of undefended prey.

    PubMed

    Halpin, Christina G; Skelhorn, John; Rowe, Candy

    2013-06-01

    Predators that have learned to associate warning coloration with toxicity often continue to include aposematic prey in their diet in order to gain the nutrients and energy that they contain. As body size is widely reported to correlate with energetic content, we predicted that prey size would affect predators' decisions to eat aposematic prey. We used a well-established system of wild-caught European starlings, Sturnus vulgaris, foraging on mealworms, Tenebrio molitor, to test how the size of undefended (water-injected) and defended (quinine-injected) prey, on different coloured backgrounds, affected birds' decisions to eat defended prey. We found that birds ate fewer defended prey, and less quinine, when undefended prey were large compared with when they were small, but that the size of the defended prey had no effect on the numbers eaten. Consequently, we found no evidence that the mass of the defended prey or the overall mass of prey ingested affected the amount of toxin that a predator was willing to ingest, and instead the mass of undefended prey eaten was more important. This is a surprising finding, challenging the assumptions of state-dependent models of aposematism and mimicry, and highlighting the need to understand better the mechanisms of predator decision making. In addition, the birds did not learn to discriminate visually between defended and undefended prey based on size, but only on the basis of colour. This suggests that colour signals may be more salient to predators than size differences, allowing Batesian mimics to benefit from aposematic models even when they differ in size.

  5. Prey-mediated avoidance of an intraguild predator by its intraguild prey

    USGS Publications Warehouse

    Wilson, R.R.; Blankenship, T.L.; Hooten, M.B.; Shivik, J.A.

    2010-01-01

    Intraguild (IG) predation is an important factor influencing community structure, yet factors allowing coexistence of IG predator and IG prey are not well understood. The existence of spatial refuges for IG prey has recently been noted for their importance in allowing coexistence. However, reduction in basal prey availability might lead IG prey to leave spatial refuges for greater access to prey, leading to increased IG predation and fewer opportunities for coexistence. We determined how the availability of prey affected space-use patterns of bobcats (Lynx rufus, IG prey) in relation to coyote space-use patterns (Canis latrans, IG predators). We located animals from fall 2007 to spring 2009 and estimated bobcat home ranges and core areas seasonally. For each bobcat relocation, we determined intensity of coyote use, distance to water, small mammal biomass, and mean small mammal biomass of the home range during the season the location was collected. We built generalized linear mixed models and used Akaike Information Criteria to determine which factors best predicted bobcat space use. Coyote intensity was a primary determinant of bobcat core area location. In bobcat home ranges with abundant prey, core areas occurred where coyote use was low, but shifted to areas intensively used by coyotes when prey declined. High spatial variability in basal prey abundance allowed some bobcats to avoid coyotes while at the same time others were forced into more risky areas. Our results suggest that multiple behavioral strategies associated with spatial variation in basal prey abundance likely allow IG prey and IG predators to coexist. ?? 2010 Springer-Verlag.

  6. Are lemmings prey or predators?

    NASA Astrophysics Data System (ADS)

    Turchin, P.; Oksanen, L.; Ekerholm, P.; Oksanen, T.; Henttonen, H.

    2000-06-01

    Large oscillations in the populations of Norwegian lemmings have mystified both professional ecologists and lay public. Ecologists suspect that these oscillations are driven by a trophic mechanism: either an interaction between lemmings and their food supply, or an interaction between lemmings and their predators. If lemming cycles are indeed driven by a trophic interaction, can we tell whether lemmings act as the resource (`prey') or the consumer (`predator')? In trophic interaction models, peaks of resource density generally have a blunt, rounded shape, whereas peaks of consumer density are sharp and angular. Here we have applied several statistical tests to three lemming datasets and contrasted them with comparable data for cyclic voles. We find that vole peaks are blunt, consistent with their cycles being driven by the interaction with predators. In contrast, the shape of lemming peaks is consistent with the hypothesis that lemmings are functional predators, that is, their cycles are driven by their interaction with food plants. Our findings suggest that a single mechanism, such as interaction between rodents and predators, is unlikely to provide the `universal' explanation of all cyclic rodent dynamics.

  7. Beaked whales echolocate on prey.

    PubMed

    Johnson, Mark; Madsen, Peter T; Zimmer, Walter M X; de Soto, Natacha Aguilar; Tyack, Peter L

    2004-12-01

    Beaked whales (Cetacea: Ziphiidea) of the genera Ziphius and Mesoplodon are so difficult to study that they are mostly known from strandings. How these elusive toothed whales use and react to sound is of concern because they mass strand during naval sonar exercises. A new non-invasive acoustic ording tag was attached to four beaked whales(two Mesoplodon densirostris and two Ziphius cavirostris) and recorded high-frequency clicks during deep dives. The tagged whales only clicked at depths below 200 m, down to a maximum depth of 1267 m. Both species produced a large number of short, directional, ultrasonic clicks with significant energy below 20 kHz. The tags recorded echoes from prey items; to our knowledge, a first for any animal echolocating in the wild. As far as we are aware, these echoes provide the first direct evidence on how free-ranging toothed whales use echolocation in foraging. The strength of these echoes suggests that the source level of Mesoplodon clicks is in the range of 200-220 dB re 1 microPa at 1 m. This paper presents conclusive data on the normal vocalizations of these beaked whale species, which may enable acoustic monitoring to mitigate exposure to sounds intense enough to harm them.

  8. Beaked whales echolocate on prey.

    PubMed Central

    Johnson, Mark; Madsen, Peter T; Zimmer, Walter M X; de Soto, Natacha Aguilar; Tyack, Peter L

    2004-01-01

    Beaked whales (Cetacea: Ziphiidea) of the genera Ziphius and Mesoplodon are so difficult to study that they are mostly known from strandings. How these elusive toothed whales use and react to sound is of concern because they mass strand during naval sonar exercises. A new non-invasive acoustic ording tag was attached to four beaked whales(two Mesoplodon densirostris and two Ziphius cavirostris) and recorded high-frequency clicks during deep dives. The tagged whales only clicked at depths below 200 m, down to a maximum depth of 1267 m. Both species produced a large number of short, directional, ultrasonic clicks with significant energy below 20 kHz. The tags recorded echoes from prey items; to our knowledge, a first for any animal echolocating in the wild. As far as we are aware, these echoes provide the first direct evidence on how free-ranging toothed whales use echolocation in foraging. The strength of these echoes suggests that the source level of Mesoplodon clicks is in the range of 200-220 dB re 1 microPa at 1 m.This paper presents conclusive data on the normal vocalizations of these beaked whale species, which may enable acoustic monitoring to mitigate exposure to sounds intense enough to harm them. PMID:15801582

  9. Campylobacter spp. and birds of prey.

    PubMed

    Dipineto, Ludovico; De Luca Bossa, Luigi Maria; Russo, Tamara Pasqualina; Cutino, Eridania Annalisa; Gargiulo, Antonio; Ciccarelli, Francesca; Raia, Pasquale; Menna, Lucia Francesca; Fioretti, Alessandro

    2014-06-01

    A total of 170 birds of prey admitted to two Wildlife Rescue and Rehabilitation Centers of Italy were examined. Birds were divided by diurnal (n = 15) and nocturnal (n = 7) species, sampled by cloacal swabs, and examined for Campylobacter spp. by cultural and molecular methods. Campylobacter spp. were isolated in 43 out of the 170 (25.3%) birds of prey examined. Among these, 43/43 (100%) were identified as Campylobacter jejuni and 10/43 (23.3%) were identified as Campylobacter coli recovered from mixed infections. Diurnal birds of prey showed a significantly higher prevalence value (P = 0.0006) for Campylobacter spp. than did nocturnal birds of prey. PMID:25055637

  10. Molecular scatology: how to improve prey DNA detection success in avian faeces?

    PubMed

    Oehm, Johannes; Juen, Anita; Nagiller, Karin; Neuhauser, Sigrid; Traugott, Michael

    2011-07-01

    The analysis of prey DNA in faeces is a non-invasive approach to examine the diet of birds. However, it is poorly known how gut transition time, environmental factors and laboratory treatments such as storage conditions or DNA extraction procedures affect the detection success of prey DNA. Here, we examined several of these factors using faeces from carrion crows fed with insect larvae. Faeces produced between 30 min and 4 h post-feeding tested positive for insect DNA, representing the gut transition time. Prey detection was not only possible in fresh but also in 5-day-old faeces. The type of surface the faeces were placed on for these 5 days, however, affected prey DNA detection success: samples placed on soil provided the lowest rate of positives compared to faeces left on leaves, on branches and within plastic tubes. Exposing faeces to sunlight and rain significantly lowered prey DNA detection rates (17% and 68% positives in exposed and protected samples, respectively). Storing faeces in ethanol or in the freezer did not affect molecular prey detection. Extracting DNA directly from larger pieces of faecal pellets resulted in significantly higher prey detection rates than when using small amounts of homogenized faeces. A cetyltrimethyl ammonium bromide-based DNA extraction protocol yielded significantly higher DNA detection rates (60%) than three commercial kits, however, for small amounts of homogenized faeces only. Our results suggest that collecting faeces from smooth, clean and non-absorbing surfaces, protected from sunlight and rain, improves DNA detection success in avian faeces. PMID:21676193

  11. Effects of the prey refuge distribution on a predator-prey system

    NASA Astrophysics Data System (ADS)

    Lee, Sang-Hee; Kwon, Ohsung; Song, Hark-Soo

    2016-03-01

    The existence of prey refuges in a predator-prey system is known to be strongly related to the ecosystem's stability. In this study, we explored how the prey refuge distribution affects the predator-prey system. To do so, we constructed a spatial lattice model to simulate an integrative predator (wolf) - prey (rabbit) - plant (grass) relationship. When a wolf (rabbit) encountered a rabbit (grass), the wolf (rabbit) tended to move to the rabbit (grass) for foraging while the rabbit tended to escape from the wolf. These behaviors were mathematically described by the degrees of willingness for hunting ( H) and escaping ( E). Initially, n refuges for prey were heterogeneously distributed in the lattice space. The heterogeneity was characterized as variable A. Higher values of A equate to higher aggregation in the refuge. We investigated the mean population density for different values of H, E, and A. To simply characterize the refuge distribution effect, we built an H-E grid map containing the population density for each species. Then, we counted the number of grids, N, with a population density ≥ 0.25. Simulation results showed that an appropriate value of A positively affected prey survival while values of A were too high had a negative effect on prey survival. The results were explained by using the trade-off between the staying time of the prey in the refuge and the cluster size of the refuge.

  12. Influence of predator mutual interference and prey refuge on Lotka-Volterra predator-prey dynamics

    NASA Astrophysics Data System (ADS)

    Chen, Liujuan; Chen, Fengde; Wang, Yiqin

    2013-11-01

    A Lotka-Volterra predator-prey model incorporating a constant number of prey using refuges and mutual interference for predator species is presented. By applying the divergency criterion and theories on exceptional directions and normal sectors, we show that the interior equilibrium is always globally asymptotically stable and two boundary equilibria are both saddle points. Our results indicate that prey refuge has no influence on the coexistence of predator and prey species of the considered model under the effects of mutual interference for predator species, which differently from the conclusion without predator mutual interference, thus improving some known ones. Numerical simulations are performed to illustrate the validity of our results.

  13. Visual illusions in predator-prey interactions: birds find moving patterned prey harder to catch.

    PubMed

    Hämäläinen, Liisa; Valkonen, Janne; Mappes, Johanna; Rojas, Bibiana

    2015-09-01

    Several antipredator strategies are related to prey colouration. Some colour patterns can create visual illusions during movement (such as motion dazzle), making it difficult for a predator to capture moving prey successfully. Experimental evidence about motion dazzle, however, is still very scarce and comes only from studies using human predators capturing moving prey items in computer games. We tested a motion dazzle effect using for the first time natural predators (wild great tits, Parus major). We used artificial prey items bearing three different colour patterns: uniform brown (control), black with elongated yellow pattern and black with interrupted yellow pattern. The last two resembled colour patterns of the aposematic, polymorphic dart-poison frog Dendrobates tinctorius. We specifically tested whether an elongated colour pattern could create visual illusions when combined with straight movement. Our results, however, do not support this hypothesis. We found no differences in the number of successful attacks towards prey items with different patterns (elongated/interrupted) moving linearly. Nevertheless, both prey types were significantly more difficult to catch compared to the uniform brown prey, indicating that both colour patterns could provide some benefit for a moving individual. Surprisingly, no effect of background (complex vs. plain) was found. This is the first experiment with moving prey showing that some colour patterns can affect avian predators' ability to capture moving prey, but the mechanisms lowering the capture rate are still poorly understood.

  14. Predator fitness increases with selectivity for odd prey.

    PubMed

    Rutz, Christian

    2012-05-01

    The fundamental currency of normative models of animal decision making is Darwinian fitness. In foraging ecology, empirical studies typically assess foraging strategies by recording energy intake rates rather than realized reproductive performance. This study provides a rare empirical link, in a vertebrate predator-prey system, between a predator's foraging behavior and direct measures of its reproductive fitness. Goshawks Accipiter gentilis selectively kill rare color variants of their principal prey, the feral pigeon Columba livia, presumably because targeting odd-looking birds in large uniform flocks helps them overcome confusion effects and enhances attack success. Reproductive performance of individual hawks increases significantly with their selectivity for odd-colored pigeons, even after controlling for confounding age effects. Older hawks exhibit more pronounced dietary preferences, suggesting that hunting performance improves with experience. Intriguingly, although negative frequency-dependent predation by hawks exerts strong selection against rare pigeon phenotypes, pigeon color polymorphism is maintained through negative assortative mating. PMID:22503502

  15. Mimicry between unequally defended prey can be parasitic: evidence for quasi-Batesian mimicry.

    PubMed

    Rowland, Hannah M; Mappes, Johanna; Ruxton, Graeme D; Speed, Michael P

    2010-12-01

    The nature of signal mimicry between defended prey (known as Müllerian mimicry) is controversial. Some authors assert that it is always mutualistic and beneficial, whilst others speculate that less well defended prey may be parasitic and degrade the protection of their better defended co-mimics (quasi-Batesian mimicry). Using great tits (Parus major) as predators of artificial prey, we show that mimicry between unequally defended co-mimics is not mutualistic, and can be parasitic and quasi-Batesian. We presented a fixed abundance of a highly defended model and a moderately defended dimorphic (mimic and distinct non-mimetic) species, and varied the relative frequency of the two forms of the moderately defended prey. As the mimic form increased in abundance, per capita predation on the model-mimic pair increased. Furthermore, when mimics were rare they gained protection from predation but imposed no co-evolutionary pressure on models. We found that the feeding decisions of the birds were affected by their individual toxic burdens, consistent with the idea that predators make foraging decisions which trade-off toxicity and nutrition. This result suggests that many prey species that are currently assumed to be in a simple mutualistic mimetic relationship with their co-mimic species may actually be engaged in an antagonistic co-evolutionary process.

  16. Porpoises: From predators to prey

    NASA Astrophysics Data System (ADS)

    Leopold, Mardik F.; Begeman, Lineke; Heße, Eileen; van der Hiele, Jaap; Hiemstra, Sjoukje; Keijl, Guido; Meesters, Erik H.; Mielke, Lara; Verheyen, Dorien; Gröne, Andrea

    2015-03-01

    Along the Dutch shores hundreds of harbour porpoises Phocoena phocoena are stranded each year. A recurrent phenomenon in the Netherlands is a surge of strandings in late winter and early spring of severely mutilated porpoises, that are mostly in good nutritional body condition (thick blubber layer). These mutilated porpoises have parts of the skin and blubber, and sometimes of the muscle tissue missing. By reviewing photographs of stranded animals taken at the stranding sites as well as autopsy results we found 273 mutilated animals from 2005 to 2012. Mutilations could be classified into several categories, but wounds had been mostly inflicted to the sides of these animals, in a zigzag fashion, or to the throat/cheek region. The stomach contents of 31 zigzags, 12 throats/cheeks and 31 control animals that were not mutilated, from the same age and blubber thickness categories were compared; all these animals had stranded between December and April, 2006-2012. The diet of individuals with zigzag lesions to their sides consisted for a large part of gobies, while animals that had wounds at the throat/cheek had been feeding predominately on clupeids. In comparison, animals without mutilations had a more varied diet, including gobies and clupeids, but also a large proportion of sandeels and gadoids. The finding that the type of mutilation corresponds to a certain diet suggests that porpoises that were feeding on different prey, or in different micro-habitats, were hit in different ways. Animals feeding at the sea floor (on gobies) apparently run a risk of being hit from the side, while animals supposedly feeding higher in the water column (on schooling clupeids), were predominantly hit from below, in the throat region. The wider variation in the diets of non-mutilated porpoises is suggestive of them using a larger variety of micro-habitats.

  17. Contribution of pitcher fragrance and fluid viscosity to high prey diversity in a Nepenthes carnivorous plant from Borneo.

    PubMed

    Giusto, Bruno Di; Grosbois, Vladimir; Fargeas, Elodie; Marshall, David J; Gaume, Laurence

    2008-03-01

    Mechanisms that improve prey richness in carnivorous plants may involve three crucial phases of trapping:attraction, capture and retention. Nepenthes rafflesiana var. typica is an insectivorous pitcher plant that is widespread in northern Borneo. It exhibits ontogenetic pitcher dimorphism with the upper pitchers trapping more flying prey than the lower pitchers. While this difference in prey composition has been ascribed to differences in attraction,the contribution of capture and retention has been overlooked. This study focused on distinguishing between the prey trapping mechanisms, and assessing their relative contribution to prey diversity. Arthropod richness and diversity of both visitors and prey in the two types of pitchers were analysed to quantify the relative contribution of attraction to prey trapping. Rate of insect visits to the different pitcher parts and the presence or absence of a sweet fragrance was recorded to clarify the origin and mechanism of attraction. The mechanism of retention was studied by insect bioassays and measurements of fluid viscosity. Nepenthes rafflesiana was found to trap a broader prey spectrum than that previously described for any Nepenthes species,with the upper pitchers attracting and trapping a greater quantity and diversity of prey items than the lower pitchers. Capture efficiency was low compared with attraction or retention efficiency. Fragrance of the peristome,or nectar rim,accounted mainly for the observed non-specific, better prey attraction by the upper pitchers, while the retentive properties of the viscous fluid in these upper pitchers arguably explains the species richness of their flying prey. The pitchers of N. rafflesiana are therefore more than simple pitfall traps and the digestive fluid plays an important yet unsuspected role in the ecological success of the species.

  18. Predator prey interactions of Procambarus clarkii with aquatic macroinvertebrates in single and multiple prey systems

    NASA Astrophysics Data System (ADS)

    Correia, Alexandra Marçal; Bandeira, Nuno; Anastácio, Pedro Manuel

    2005-11-01

    Understanding the interspecific interactions of Procambarus clarkii with other aquatic macroinvertebrates will help to unveil the mechanisms and processes underlying biological invasiveness. The purpose of this study was to investigate predator-prey interactions of two ontogenic phases of P. clarkii with native and exotic species of aquatic macroinvertebrates at a single and multiple prey level. We performed laboratory experiments to determine the consumption and the behavioral responses of Chironomus riparius, Physa acuta and Corbicula fluminea to P. clarkii. The presence of P. clarkii significantly affected the abundance of C. riparius and P. acuta, but not of C. fluminea whether prey species were provided singly or simultaneously. The consumption of C. riparius by P. clarkii was higher than P. acuta for both crayfish sizes and situations (single/multiple prey systems) and C. fluminea was never consumed. Physa acuta was the only species that exhibited an anti-predator behavior to P. clarkii. Our results show that P. clarkii can have strong consumptive and trait effects on aquatic macroinvertebrate prey at a single and multiple prey level, resulting in differential impacts on different prey species. This study clarifies some aspects of the predator-prey interactions between P. clarkii and native as well as other exotic macroinvertebrate species that have invaded freshwater biocenosis worldwide.

  19. Restructuring fundamental predator-prey models by recognising prey-dependent conversion efficiency and mortality rates.

    PubMed

    Li, Jiqiu; Montagnes, David J S

    2015-05-01

    Incorporating protozoa into population models (from simple predator-prey explorations to complex food web simulations) is of conceptual, ecological, and economic importance. From theoretical and empirical perspectives, we expose unappreciated complexity in the traditional predator-prey model structure and provide a parsimonious solution, especially for protistologists. We focus on how prey abundance alters two key components of models: predator conversion efficiency (e, the proportion of prey converted to predator, before mortality loss) and predator mortality (δ, the portion of the population lost though death). Using a well-established model system (Paramecium and Didinium), we collect data to parameterize a range of existing and novel population models that differ in the functional forms of e and δ. We then compare model simulations to an empirically obtained time-series of predator-prey population dynamics. The analysis indicates that prey-dependent e and δ should be considered when structuring population models and that both prey and predator biomass also vary with prey abundance. Both of these impact the ability of the model to predict population dynamics and, therefore, should be included in theoretical model evaluations and assessment of ecosystem dynamics associated with biomass flux. PMID:25819465

  20. How the Magnitude of Prey Genetic Variation Alters Predator-Prey Eco-Evolutionary Dynamics.

    PubMed

    Cortez, Michael H

    2016-09-01

    Evolution can alter the stability and dynamics of ecological communities; for example, prey evolution can drive cyclic dynamics in predator-prey systems that are not possible in the absence of evolution. However, it is unclear how the magnitude of additive genetic variation in the evolving species mediates those effects. In this study, I explore how the magnitude of prey additive genetic variation determines what effects prey evolution has on the dynamics and stability of predator-prey systems. I use linear stability analysis to decompose the stability of a general eco-evolutionary predator-prey model into components representing the stabilities of the ecological and evolutionary subsystems as well as the interactions between those subsystems. My results show that with low genetic variation, the cyclic dynamics and stability of the system are determined by the ecological subsystem. With increased genetic variation, disruptive selection always destabilizes stable communities, stabilizing selection can stabilize or destabilize communities, and prey evolution can alter predator-prey phase lags. Stability changes occur approximately when the magnitude of genetic variation balances the (in)stabilities of the ecological and evolutionary subsystems. I discuss the connections between my stability results and prior results from the theory of adaptive dynamics.

  1. Restructuring fundamental predator-prey models by recognising prey-dependent conversion efficiency and mortality rates.

    PubMed

    Li, Jiqiu; Montagnes, David J S

    2015-05-01

    Incorporating protozoa into population models (from simple predator-prey explorations to complex food web simulations) is of conceptual, ecological, and economic importance. From theoretical and empirical perspectives, we expose unappreciated complexity in the traditional predator-prey model structure and provide a parsimonious solution, especially for protistologists. We focus on how prey abundance alters two key components of models: predator conversion efficiency (e, the proportion of prey converted to predator, before mortality loss) and predator mortality (δ, the portion of the population lost though death). Using a well-established model system (Paramecium and Didinium), we collect data to parameterize a range of existing and novel population models that differ in the functional forms of e and δ. We then compare model simulations to an empirically obtained time-series of predator-prey population dynamics. The analysis indicates that prey-dependent e and δ should be considered when structuring population models and that both prey and predator biomass also vary with prey abundance. Both of these impact the ability of the model to predict population dynamics and, therefore, should be included in theoretical model evaluations and assessment of ecosystem dynamics associated with biomass flux.

  2. How the Magnitude of Prey Genetic Variation Alters Predator-Prey Eco-Evolutionary Dynamics.

    PubMed

    Cortez, Michael H

    2016-09-01

    Evolution can alter the stability and dynamics of ecological communities; for example, prey evolution can drive cyclic dynamics in predator-prey systems that are not possible in the absence of evolution. However, it is unclear how the magnitude of additive genetic variation in the evolving species mediates those effects. In this study, I explore how the magnitude of prey additive genetic variation determines what effects prey evolution has on the dynamics and stability of predator-prey systems. I use linear stability analysis to decompose the stability of a general eco-evolutionary predator-prey model into components representing the stabilities of the ecological and evolutionary subsystems as well as the interactions between those subsystems. My results show that with low genetic variation, the cyclic dynamics and stability of the system are determined by the ecological subsystem. With increased genetic variation, disruptive selection always destabilizes stable communities, stabilizing selection can stabilize or destabilize communities, and prey evolution can alter predator-prey phase lags. Stability changes occur approximately when the magnitude of genetic variation balances the (in)stabilities of the ecological and evolutionary subsystems. I discuss the connections between my stability results and prior results from the theory of adaptive dynamics. PMID:27501090

  3. Blue whale habitat and prey in the California Channel Islands

    NASA Astrophysics Data System (ADS)

    Fiedler, Paul C.; Reilly, Stephen B.; Hewitt, Roger P.; Demer, David; Philbrick, Valerie A.; Smith, Susan; Armstrong, Wesley; Croll, Donald A.; Tershy, Bernie R.; Mate, Bruce R.

    1998-08-01

    Whale Habitat and Prey Studies were conducted off southern California during August 1995 (WHAPS95) and July 1996 (WHAPS96) to (1) study the distribution and activities of blue whales and other large whales, (2) survey the distribution of prey organisms (krill), and (3) measure physical and biological habitat variables that influence the distribution of whales and prey. A total of 1307 cetacean sightings included 460 blue whale, 78 fin whale and 101 humpback whale sightings. Most blue whales were found in cold, well-mixed and productive water that had upwelled along the coast north of Point Conception and then advected south. They were aggregated in this water near San Miguel and Santa Rosa Islands, where they fed on dense, subsurface layers of euphausiids both on the shelf and extending off the shelf edge. Two species of euphausiids were consumed by blue whales, Thysanoessa spinifera and Euphausia pacifica, with evidence of preference for the former, a larger and more coastal species. These krill patches on the Channel Island feeding grounds are a resource exploited during summer-fall by the world's largest stock of blue whales.

  4. Flash visual evoked potentials in diurnal birds of prey.

    PubMed

    Dondi, Maurizio; Biaggi, Fabio; Di Ianni, Francesco; Dodi, Pier Luigi; Quintavalla, Fausto

    2016-01-01

    The objective of this pilot study was to evaluate the feasibility of Flash Visual Evoked Potentials (FVEPs) testing in birds of prey in a clinical setting and to describe the protocol and the baseline data for normal vision in this species. FVEP recordings were obtained from 6 normal adult birds of prey: n. 2 Harris's Hawks (Parabuteo unicinctus), n. 1 Lanner Falcon (Falco biarmicus), n. 2 Gyrfalcons (Falco rusticolus) and n. 1 Saker Falcon (Falco cherrug). Before carrying out VEP tests, all animals underwent neurologic and ophthalmic routine examination. Waveforms were analysed to identify reproducible peaks from random variation of baseline. At least three positive and negative peaks were highlighted in all tracks with elevated repeatability. Measurements consisted of the absolute and relative latencies of these peaks (P1, N1, P2, N2, P3, and N3) and their peak-to-peak amplitudes. Both the peak latency and wave morphology achieved from normal animals were similar to those obtained previously in other animal species. This test can be easily and safely performed in a clinical setting in birds of prey and could be useful for an objective assessment of visual function. PMID:27547536

  5. Flash visual evoked potentials in diurnal birds of prey

    PubMed Central

    Biaggi, Fabio; Di Ianni, Francesco; Dodi, Pier Luigi; Quintavalla, Fausto

    2016-01-01

    The objective of this pilot study was to evaluate the feasibility of Flash Visual Evoked Potentials (FVEPs) testing in birds of prey in a clinical setting and to describe the protocol and the baseline data for normal vision in this species. FVEP recordings were obtained from 6 normal adult birds of prey: n. 2 Harris’s Hawks (Parabuteo unicinctus), n. 1 Lanner Falcon (Falco biarmicus), n. 2 Gyrfalcons (Falco rusticolus) and n. 1 Saker Falcon (Falco cherrug). Before carrying out VEP tests, all animals underwent neurologic and ophthalmic routine examination. Waveforms were analysed to identify reproducible peaks from random variation of baseline. At least three positive and negative peaks were highlighted in all tracks with elevated repeatability. Measurements consisted of the absolute and relative latencies of these peaks (P1, N1, P2, N2, P3, and N3) and their peak-to-peak amplitudes. Both the peak latency and wave morphology achieved from normal animals were similar to those obtained previously in other animal species. This test can be easily and safely performed in a clinical setting in birds of prey and could be useful for an objective assessment of visual function. PMID:27547536

  6. System for measurement of headband force in hearing protection devices and audiometric equipment

    NASA Astrophysics Data System (ADS)

    Llamas-Llamas, Osvaldo; Razo-Razo, Jose-Noe

    2002-11-01

    Application force influences audiometric results and hearing protection devices (HPD) attenuation performance. In HPD attenuation testing it is neccessary to know the application force. Audiometric studies are being conducted with standardized values of the application force. Design and results of a measurement device for bands and headbands application force are presented. Error analysis in the range from 1N to 30N is carried out and the associated measurement uncertainty is estimated. The device provides settings for test distances from 70 mm to 140 mm (vertical axis), and 115 mm to 195 mm (horizontal axis), as required in most of the available standards related with HPD and audiometric equipment.

  7. Measured catalycities of various candidate space shuttle thermal protection system coatings at low temperatures

    NASA Technical Reports Server (NTRS)

    Scott, C. D.

    1973-01-01

    Atom recombination catalytic rates for surface coatings of various candidate thermal protection system materials for the space shuttle vehicle were obtained from measurements in arc jet, air flow. The coatings, chrome oxides, siliconized carbon/carbon, hafnium/tantalum carbide on carbon/carbon, and niobium silicide, were bonded to the sensitive surface of transient slug calorimeters that measured the heat transfer rates to the coatings. The catalytic rates were inferred from these heat transfer rates Surface temperatures of the calorimeters varied from approximately 300 to 410 K.

  8. Status of pelagic prey fishes in Lake Michigan, 2013

    USGS Publications Warehouse

    Warner, David M.; Farha, Steven A.; O'Brien, Timothy P.; Ogilvie, Lynn; Claramunt, Randall M.; Hanson, Dale

    2014-01-01

    Acoustic surveys were conducted in late summer/early fall during the years 1992-1996 and 2001-2013 to estimate pelagic prey fish biomass in Lake Michigan. Midwater trawling during the surveys as well as target strength provided a measure of species and size composition of the fish community for use in scaling acoustic data and providing species-specific abundance estimates. The 2013 survey consisted of 27 acoustic transects (546 km total) and 31 midwater trawl tows. Mean prey fish biomass was 6.1 kg/ha (relative standard error, RSE = 11%) or 29.6 kilotonnes (kt = 1,000 metric tons), which was similar to the estimate in 2012 (31.1 kt) and 23.5% of the long-term (18 years) mean. The numeric density of the 2013 alewife year class was 6% of the time series average and this year-class contributed 4% of total alewife biomass (5.2 kg/ha, RSE = 12%). Alewife ≥age-1 comprised 96% of alewife biomass. In 2013, alewife comprised 86% of total prey fish biomass, while rainbow smelt and bloater were 4 and 10% of total biomass, respectively. Rainbow smelt biomass in 2013 (0.24 kg/ha, RSE = 17%) was essentially identical to the rainbow smelt biomass in 2012 and was 6% of the long term mean. Bloater biomass in 2013 was 0.6 kg/ha, only half the 2012 biomass, and 6% of the long term mean. Mean density of small bloater in 2013 (29 fish/ha, RSE = 29%) was lower than peak values observed in 2007-2009 and was 23% of the time series mean. In 2013, pelagic prey fish biomass in Lake Michigan was similar to Lake Huron, but pelagic community composition differs in the two lakes, with Lake Huron dominated by bloater.

  9. An impulsive predator-prey model with disease in the prey for integrated pest management

    NASA Astrophysics Data System (ADS)

    Shi, Ruiqing; Chen, Lansun

    2010-02-01

    In this paper, an impulsive predator-prey model with disease in the prey is investigated for the purpose of integrated pest management. In the first part of the main results, we get the sufficient condition for the global stability of the susceptible pest-eradication periodic solution. This means if the release amount of infective prey and predator satisfy the condition, then the pest will be doomed. In the second part of the main results, we also get the sufficient condition for the permanence of the system. This means if the release amount of infective prey and predator satisfy the condition, then the prey and the predator will coexist. In the last section, we interpret our mathematical results. We also point out some possible future work.

  10. Sheltering--a protective measure following an accidental atmospheric release from a nuclear power plant

    SciTech Connect

    Koch, J.; Tadmor, J.

    1988-06-01

    The effectiveness of sheltering the population for reducing radiological effects following an accidental release of radioactivity at a nuclear power plant was investigated. Different levels of respiratory protection and the administration of a thyroid blocking agent were also studied as possible complements to sheltering. Specific conditions were assumed, concerning the high protection factors of regular buildings and the high availability of civil defense shelters. Computations were performed by means of a probabilistic consequence model, which allows a comprehensive description of exposure modes and processes dealing with the implementation of sheltering and which takes into account a broad range of radiological effects. Sheltering, even in regular buildings, was found to be efficient in reducing early fatalities and other non-stochastic effects. However, it was shown that respiratory protection is also needed in order to alleviate stochastic effects and that, for this purpose, expedient individual filtration methods may be satisfactory. Under the conditions studied, sheltering was found to be preferable in most cases over evacuation, as the main immediate protective measure, unless evacuation can be carried out before the radioactive cloud reaches the populated area.

  11. Measurement of impulse peak insertion loss for four hearing protection devices in field conditions

    PubMed Central

    Murphy, William J.; Flamme, Gregory A.; Meinke, Deanna K.; Sondergaard, Jacob; Finan, Donald S.; Lankford, James E.; Khan, Amir; Vernon, Julia; Stewart, Michael

    2015-01-01

    Objective In 2009, the U.S. Environmental Protection Agency (EPA) proposed an impulse noise reduction rating (NRR) for hearing protection devices based upon the impulse peak insertion loss (IPIL) methods in the ANSI S12.42-2010 standard. This study tests the ANSI S12.42 methods with a range of hearing protection devices measured in field conditions. Design The method utilizes an acoustic test fixture and three ranges for impulse levels: 130–134, 148–152, and 166–170 dB peak SPL. For this study, four different models of hearing protectors were tested: Bilsom 707 Impact II electronic earmuff, E·A·R Pod Express, E·A·R Combat Arms version 4, and the Etymotic Research, Inc. Electronic BlastPLG™ EB1. Study sample Five samples of each protector were fitted on the fixture or inserted in the fixture's ear canal five times for each impulse level. Impulses were generated by a 0.223 caliber rifle. Results The average IPILs increased with peak pressure and ranged between 20 and 38 dB. For some protectors, significant differences were observed across protector examples of the same model, and across insertions. Conclusions The EPA's proposed methods provide consistent and reproducible results. The proposed impulse NRR rating should utilize the minimum and maximum protection percentiles as determined by the ANSI S12.42-2010 methods. PMID:22176308

  12. Revision of the Measurement Tool for Patients' Health Information Protection Awareness

    PubMed Central

    Song, Youngshin; Lee, Miyoung; Jun, Younghee; Lee, Yoonhee; Cho, Jeonghwa; Kwon, Myoungjin

    2016-01-01

    Objectives Despite the importance of the protection of patients' health information in clinical settings, little is known about the awareness of this concept in nursing students due to the lack of a suitable measurement tool. Hence, this study attempted to redevelop the Patients' Health Information Protection Awareness Scale, and evaluate its construct validity and reliability for nursing students. Methods A cross-sectional descriptive study was conducted. Nursing students who were in their 3rd and 4th year were recruited from 10 universities in Korea to assess the construct validity, and 30 experts (27 nurses and 3 faculty members) participated in the content validation process. Results The content validity assessment indicated that 23 items were ideal. The assessment of construct validity using exploratory factor analysis revealed three factors: communication, management, and referrals. They together accounted for 54.1% of the variance in scale scores. The three-factor scale had good fit in the confirmatory factor analysis. Scale reliability was confirmed, with a Cronbach's alpha of 0.94 for all items. Conclusions This study was the first attempt to redevelop the Patients' Health Information Protection Awareness Scale for student nurses. The 23-item scale was shown to be a reliable and valid tool. It facilitates the assessment of nursing students' awareness of patient information protection. Academic nursing programs and health organizations can use its scores to implement adequate education plans to safeguard information in nursing students. PMID:27525162

  13. Selective Predation of a Stalking Predator on Ungulate Prey.

    PubMed

    Heurich, Marco; Zeis, Klara; Küchenhoff, Helmut; Müller, Jörg; Belotti, Elisa; Bufka, Luděk; Woelfing, Benno

    2016-01-01

    Prey selection is a key factor shaping animal populations and evolutionary dynamics. An optimal forager should target prey that offers the highest benefits in terms of energy content at the lowest costs. Predators are therefore expected to select for prey of optimal size. Stalking predators do not pursue their prey long, which may lead to a more random choice of prey individuals. Due to difficulties in assessing the composition of available prey populations, data on prey selection of stalking carnivores are still scarce. We show how the stalking predator Eurasian lynx (Lynx lynx) selects prey individuals based on species identity, age, sex and individual behaviour. To address the difficulties in assessing prey population structure, we confirm inferred selection patterns by using two independent data sets: (1) data of 387 documented kills of radio-collared lynx were compared to the prey population structure retrieved from systematic camera trapping using Manly's standardized selection ratio alpha and (2) data on 120 radio-collared roe deer were analysed using a Cox proportional hazards model. Among the larger red deer prey, lynx selected against adult males-the largest and potentially most dangerous prey individuals. In roe deer lynx preyed selectively on males and did not select for a specific age class. Activity during high risk periods reduced the risk of falling victim to a lynx attack. Our results suggest that the stalking predator lynx actively selects for size, while prey behaviour induces selection by encounter and stalking success rates. PMID:27548478

  14. Selective Predation of a Stalking Predator on Ungulate Prey

    PubMed Central

    Heurich, Marco; Zeis, Klara; Küchenhoff, Helmut; Müller, Jörg; Belotti, Elisa; Bufka, Luděk; Woelfing, Benno

    2016-01-01

    Prey selection is a key factor shaping animal populations and evolutionary dynamics. An optimal forager should target prey that offers the highest benefits in terms of energy content at the lowest costs. Predators are therefore expected to select for prey of optimal size. Stalking predators do not pursue their prey long, which may lead to a more random choice of prey individuals. Due to difficulties in assessing the composition of available prey populations, data on prey selection of stalking carnivores are still scarce. We show how the stalking predator Eurasian lynx (Lynx lynx) selects prey individuals based on species identity, age, sex and individual behaviour. To address the difficulties in assessing prey population structure, we confirm inferred selection patterns by using two independent data sets: (1) data of 387 documented kills of radio-collared lynx were compared to the prey population structure retrieved from systematic camera trapping using Manly’s standardized selection ratio alpha and (2) data on 120 radio-collared roe deer were analysed using a Cox proportional hazards model. Among the larger red deer prey, lynx selected against adult males—the largest and potentially most dangerous prey individuals. In roe deer lynx preyed selectively on males and did not select for a specific age class. Activity during high risk periods reduced the risk of falling victim to a lynx attack. Our results suggest that the stalking predator lynx actively selects for size, while prey behaviour induces selection by encounter and stalking success rates. PMID:27548478

  15. Selective Predation of a Stalking Predator on Ungulate Prey.

    PubMed

    Heurich, Marco; Zeis, Klara; Küchenhoff, Helmut; Müller, Jörg; Belotti, Elisa; Bufka, Luděk; Woelfing, Benno

    2016-01-01

    Prey selection is a key factor shaping animal populations and evolutionary dynamics. An optimal forager should target prey that offers the highest benefits in terms of energy content at the lowest costs. Predators are therefore expected to select for prey of optimal size. Stalking predators do not pursue their prey long, which may lead to a more random choice of prey individuals. Due to difficulties in assessing the composition of available prey populations, data on prey selection of stalking carnivores are still scarce. We show how the stalking predator Eurasian lynx (Lynx lynx) selects prey individuals based on species identity, age, sex and individual behaviour. To address the difficulties in assessing prey population structure, we confirm inferred selection patterns by using two independent data sets: (1) data of 387 documented kills of radio-collared lynx were compared to the prey population structure retrieved from systematic camera trapping using Manly's standardized selection ratio alpha and (2) data on 120 radio-collared roe deer were analysed using a Cox proportional hazards model. Among the larger red deer prey, lynx selected against adult males-the largest and potentially most dangerous prey individuals. In roe deer lynx preyed selectively on males and did not select for a specific age class. Activity during high risk periods reduced the risk of falling victim to a lynx attack. Our results suggest that the stalking predator lynx actively selects for size, while prey behaviour induces selection by encounter and stalking success rates.

  16. Breaking symmetry: the marine environment, prey size, and the evolution of asymmetry in cetacean skulls.

    PubMed

    MacLeod, C D; Reidenberg, J S; Weller, M; Santos, M B; Herman, J; Goold, J; Pierce, G J

    2007-06-01

    Skulls of odontocetes (toothed whales, including dolphins and porpoises) are typified by directional asymmetry, particularly in elements associated with the airway. Generally, it is assumed this asymmetry is related to biosonar production. However, skull asymmetry may actually be a by-product of selection pressure for an asymmetrically positioned larynx. The odontocete larynx traverses the pharynx and is held permanently in place by a ring of muscle. This allows prey swallowing while remaining underwater without risking water entering the lungs and causing injury or death. However, protrusion of the larynx through the pharynx causes a restriction around which prey must pass to reach the stomach. The larynx and associated hyoid apparatus has, therefore, been shifted to the left to provide a larger right piriform sinus (lateral pharyngeal food channel) for swallowing larger prey items. This asymmetry is reflected in the skull, particularly the dorsal openings of the nares. It is hypothesized that there is a relationship between prey size and skull asymmetry. This relationship was examined in 13 species of odontocete cetaceans from the northeast Atlantic, including four narrow-gaped genera (Mesoplodon, Ziphius, Hyperoodon, and Kogia) and eight wide-gaped genera (Phocoena, Delphinus, Stenella, Lagenorhynchus, Tursiops, Grampus, Globicephala, and Orcinus). Skulls were examined from 183 specimens to assess asymmetry of the anterior choanae. Stomach contents were examined from 294 specimens to assess prey size. Results show there is a significant positive relationship between maximum relative prey size consumed and average asymmetry relative to skull size in odontocete species (wide-gape species: R2 = 0.642, P = 0.006; narrow-gape species: R2 = 0.909, P = 0.031). This finding provides support for the hypothesis that the directional asymmetry found in odontocete skulls is related to an aquatic adaptation enabling swallowing large, whole prey while maintaining respiratory

  17. Prey responses to predator chemical cues: disentangling the importance of the number and biomass of prey consumed.

    PubMed

    McCoy, Michael W; Touchon, Justin C; Landberg, Tobias; Warkentin, Karen M; Vonesh, James R

    2012-01-01

    To effectively balance investment in predator defenses versus other traits, organisms must accurately assess predation risk. Chemical cues caused by predation events are indicators of risk for prey in a wide variety of systems, but the relationship between how prey perceive risk in relation to the amount of prey consumed by predators is poorly understood. While per capita predation rate is often used as the metric of relative risk, studies aimed at quantifying predator-induced defenses commonly control biomass of prey consumed as the metric of risk. However, biomass consumed can change by altering either the number or size of prey consumed. In this study we determine whether phenotypic plasticity to predator chemical cues depends upon prey biomass consumed, prey number consumed, or both. We examine the growth response of red-eyed treefrog tadpoles (Agalychnis callidryas) to cues from a larval dragonfly (Anax amazili). Biomass consumed was manipulated by either increasing the number of prey while holding individual prey size constant, or by holding the number of prey constant and varying individual prey size. We address two questions. (i) Do prey reduce growth rate in response to chemical cues in a dose dependent manner? (ii) Does the magnitude of the response depend on whether prey consumption increases via number or size of prey? We find that the phenotypic response of prey is an asymptotic function of prey biomass consumed. However, the asymptotic response is higher when more prey are consumed. Our findings have important implications for evaluating past studies and how future experiments should be designed. A stronger response to predation cues generated by more individual prey deaths is consistent with models that predict prey sensitivity to per capita risk, providing a more direct link between empirical and theoretical studies which are often focused on changes in population sizes not individual biomass.

  18. Effects of prey assemblage on mercury bioaccumulation in a piscivorous sport fish.

    PubMed

    Johnson, Brett M; Lepak, Jesse M; Wolff, Brian A

    2015-02-15

    Mercury (Hg) is a persistent global contaminant that biomagnifies, often reaching maximum levels in apex predators. Mercury contamination in piscivorous fish is a serious health risk for anglers and other fish consumers. We used data collected from a reservoir in Colorado to develop bioenergetics-based simulations of Hg bioaccumulation to estimate Hg concentrations in walleye (Sander vitreus), a popular sport fish. We evaluated how changes in the prey available to walleye might affect walleye Hg concentrations. Our simulations showed that such changes could result in almost a 10-fold range in walleye Hg concentration. Walleye consuming invertebrates had low growth, low growth efficiency, and high Hg concentrations. Conversely, when walleye diet contained only fish prey their growth and growth efficiency were higher and Hg concentrations were about 85% lower. These predictions were consistent with independent measurements in the study system observed under two different prey regimes in 2008 and 2013. Because prey assemblages in freshwaters can exhibit high natural and anthropogenic variability, understanding variation in predator Hg and providing accurate fish consumption advice to anglers and their families will require frequent monitoring of both predator and prey species. Further, manipulation of prey assemblages is a routine fishery management strategy that could be applied to reduce Hg contamination in piscivorous fishes.

  19. Effects of predator hunger and food abundance on prey selection by Chaoborus larvae

    SciTech Connect

    Pastorok, R.A.

    1980-09-01

    Laboratory experiments on prey selection by Chaoborus larvae show that predator choice as well as differential encounter rates with prey determine the composition of the diet. As the larvae crop and midgut become filled with food during a feeding bout, the predator avoids eating some available Daphnia and specializes on Diaptomus. After 3 days of starvation at 15/sup 0/C, the gut system is empty and Chaoborus attacks prey indiscriminately. Then, daphnids are overrepresented in the diet because the predator encounters them more frequently than copepods of equal size. Daphnia swims about twice as fast as Diaptomus and encounters a stationary electric eye at twice the rate measured for copepods. The strike efficiency of larvae for encountered prey is the same for both species. Since feeding selectivity is inversely proportional to larval hunger state, prey selection varies with the abundance of prey and season. In general, larvae collected during autumn have lower feeding rates and are more selective than larvae collected during summer. When food increases, previously opportunistic larvae may become selective within a few hours; but satiated larvae take several days to relax their preferences under a lowered food regime.

  20. Oxytocin tempers calculated greed but not impulsive defense in predator–prey contests

    PubMed Central

    Scholte, H. Steven; van Winden, Frans A. A. M.; Ridderinkhof, K. Richard

    2015-01-01

    Human cooperation and competition is modulated by oxytocin, a hypothalamic neuropeptide that functions as both hormone and neurotransmitter. Oxytocin’s functions can be captured in two explanatory yet largely contradictory frameworks: the fear-dampening (FD) hypothesis that oxytocin has anxiolytic effects and reduces fear-motivated action; and the social approach/avoidance (SAA) hypothesis that oxytocin increases cooperative approach and facilitates protection against aversive stimuli and threat. We tested derivations from both frameworks in a novel predator–prey contest game. Healthy males given oxytocin or placebo invested as predator to win their prey’s endowment, or as prey to protect their endowment against predation. Neural activity was registered using 3T-MRI. In prey, (fear-motivated) investments were fast and conditioned on the amygdala. Inconsistent with FD, oxytocin did not modulate neural and behavioral responding in prey. In predators, (greed-motivated) investments were slower, and conditioned on the superior frontal gyrus (SFG). Consistent with SAA, oxytocin reduced predator investment, time to decide and activation in SFG. Thus, whereas oxytocin does not incapacitate the impulsive ability to protect and defend oneself, it lowers the greedy and more calculated appetite for coming out ahead. PMID:25140047

  1. Predator functional response and prey survival: direct and indirect interactions affecting a marked prey population.

    PubMed

    Miller, David A; Grand, James B; Fondell, Thomas F; Anthony, Michael

    2006-01-01

    1. Predation plays an integral role in many community interactions, with the number of predators and the rate at which they consume prey (i.e. their functional response) determining interaction strengths. Owing to the difficulty of directly observing predation events, attempts to determine the functional response of predators in natural systems are limited. Determining the forms that predator functional responses take in complex systems is important in advancing understanding of community interactions. 2. Prey survival has a direct relationship to the functional response of their predators. We employed this relationship to estimate the functional response for bald eagle Haliaeetus leucocepalus predation of Canada goose Branta canadensis nests. We compared models that incorporated eagle abundance, nest abundance and alternative prey presence to determine the form of the functional response that best predicted intra-annual variation in survival of goose nests. 3. Eagle abundance, nest abundance and the availability of alternative prey were all related to predation rates of goose nests by eagles. There was a sigmoidal relationship between predation rate and prey abundance and prey switching occurred when alternative prey was present. In addition, predation by individual eagles increased as eagle abundance increased. 4. A complex set of interactions among the three species examined in this study determined survival rates of goose nests. Results show that eagle predation had both prey- and predator-dependent components with no support for ratio dependence. In addition, indirect interactions resulting from the availability of alternative prey had an important role in mediating the rate at which eagles depredated nests. As a result, much of the within-season variation in nest survival was due to changing availability of alternative prey consumed by eagles. 5. Empirical relationships drawn from ecological theory can be directly integrated into the estimation process to

  2. Predator functional response and prey survival: Direct and indirect interactions affecting a marked prey population

    USGS Publications Warehouse

    Miller, David A.; Grand, J.B.; Fondell, T.F.; Anthony, M.

    2006-01-01

    1. Predation plays an integral role in many community interactions, with the number of predators and the rate at which they consume prey (i.e. their functional response) determining interaction strengths. Owing to the difficulty of directly observing predation events, attempts to determine the functional response of predators in natural systems are limited. Determining the forms that predator functional responses take in complex systems is important in advancing understanding of community interactions. 2. Prey survival has a direct relationship to the functional response of their predators. We employed this relationship to estimate the functional response for bald eagle Haliaeetus leucocepalus predation of Canada goose Branta canadensis nests. We compared models that incorporated eagle abundance, nest abundance and alternative prey presence to determine the form of the functional response that best predicted intra-annual variation in survival of goose nests. 3. Eagle abundance, nest abundance and the availability of alternative prey were all related to predation rates of goose nests by eagles. There was a sigmoidal relationship between predation rate and prey abundance and prey switching occurred when alternative prey was present. In addition, predation by individual eagles increased as eagle abundance increased. 4. A complex set of interactions among the three species examined in this study determined survival rates of goose nests. Results show that eagle predation had both prey- and predator-dependent components with no support for ratio dependence. In addition, indirect interactions resulting from the availability of alternative prey had an important role in mediating the rate at which eagles depredated nests. As a result, much of the within-season variation in nest survival was due to changing availability of alternative prey consumed by eagles. 5. Empirical relationships drawn from ecological theory can be directly integrated into the estimation process to

  3. Measuring the spectral emissivity of thermal protection materials during atmospheric reentry simulation

    NASA Technical Reports Server (NTRS)

    Marble, Elizabeth

    1996-01-01

    Hypersonic spacecraft reentering the earth's atmosphere encounter extreme heat due to atmospheric friction. Thermal Protection System (TPS) materials shield the craft from this searing heat, which can reach temperatures of 2900 F. Various thermophysical and optical properties of TPS materials are tested at the Johnson Space Center Atmospheric Reentry Materials and Structures Evaluation Facility, which has the capability to simulate critical environmental conditions associated with entry into the earth's atmosphere. Emissivity is an optical property that determines how well a material will reradiate incident heat back into the atmosphere upon reentry, thus protecting the spacecraft from the intense frictional heat. This report describes a method of measuring TPS emissivities using the SR5000 Scanning Spectroradiometer, and includes system characteristics, sample data, and operational procedures developed for arc-jet applications.

  4. Interactions between spatially explicit conservation and management measures: implications for the governance of marine protected areas.

    PubMed

    Cárcamo, P Francisco; Gaymer, Carlos F

    2013-12-01

    Marine protected areas are not established in an institutional and governance vacuum and managers should pay attention to the wider social-ecological system in which they are immersed. This article examines Islas Choros-Damas Marine Reserve, a small marine protected area located in a highly productive and biologically diverse coastal marine ecosystem in northern Chile, and the interactions between human, institutional, and ecological dimensions beyond those existing within its boundaries. Through documents analysis, surveys, and interviews, we described marine reserve implementation (governing system) and the social and natural ecosystem-to-be-governed. We analyzed the interactions and the connections between the marine reserve and other spatially explicit conservation and/or management measures existing in the area and influencing management outcomes and governance. A top-down approach with poor stakeholder involvement characterized the implementation process. The marine reserve is highly connected with other spatially explicit measures and with a wider social-ecological system through various ecological processes and socio-economic interactions. Current institutional interactions with positive effects on the management and governance are scarce, although several potential interactions may be developed. For the study area, any management action must recognize interferences from outside conditions and consider some of them (e.g., ecotourism management) as cross-cutting actions for the entire social-ecological system. We consider that institutional interactions and the development of social networks are opportunities to any collective effort aiming to improve governance of Islas Choros-Damas marine reserve. Communication of connections and interactions between marine protected areas and the wider social-ecological system (as described in this study) is proposed as a strategy to improve stakeholder participation in Chilean marine protected areas.

  5. Nanoparticle usage and protection measures in the manufacturing industry--a representative survey.

    PubMed

    Schmid, Kaspar; Danuser, Brigitta; Riediker, Michael

    2010-04-01

    Addressing the risks of nanoparticles requires knowledge about release into the environment and occupational exposure. However, such information currently is not systematically collected; therefore, this risk assessment lacks quantitative data. The goal was to evaluate the current level of nanoparticle usage in Swiss industry as well as health, safety, and environmental measures, and the number of potentially exposed workers. A representative, stratified mail survey was conducted among 1626 clients of the Swiss National Accident Insurance Fund (SUVA), which insures 80,000 manufacturing firms, representing 84% of all Swiss manufacturing companies (947 companies answered the survey for a 58.3% response rate). The extrapolation to all Swiss manufacturing companies results in 1309 workers (95% confidence interval [CI]: 1073 to 1545) potentially exposed to nanoparticles in 586 companies (95% CI: 145 to 1027). This corresponds to 0.08% of workers (95% CI: 0.06% to 0.09%) and to 0.6% of companies (95% CI: 0.2% to 1.1%). The industrial chemistry sector showed the highest percentage of companies using nanoparticles (21.2%). Other important sectors also reported nanoparticles. Personal protection equipment was the predominant protection strategy. Only a few applied specific environmental protection measures. This is the first nationwide representative study on nanoparticle use in the manufacturing sector. The information gained can be used for quantitative risk assessment. It can also help policymakers design strategies to support companies developing a safer use of nanomaterial. Noting the current low use of nanoparticles, there is still time to proactively introduce protective methods. If the predicted "nano-revolution" comes true, now is the time to take action.

  6. Interactions between spatially explicit conservation and management measures: implications for the governance of marine protected areas.

    PubMed

    Cárcamo, P Francisco; Gaymer, Carlos F

    2013-12-01

    Marine protected areas are not established in an institutional and governance vacuum and managers should pay attention to the wider social-ecological system in which they are immersed. This article examines Islas Choros-Damas Marine Reserve, a small marine protected area located in a highly productive and biologically diverse coastal marine ecosystem in northern Chile, and the interactions between human, institutional, and ecological dimensions beyond those existing within its boundaries. Through documents analysis, surveys, and interviews, we described marine reserve implementation (governing system) and the social and natural ecosystem-to-be-governed. We analyzed the interactions and the connections between the marine reserve and other spatially explicit conservation and/or management measures existing in the area and influencing management outcomes and governance. A top-down approach with poor stakeholder involvement characterized the implementation process. The marine reserve is highly connected with other spatially explicit measures and with a wider social-ecological system through various ecological processes and socio-economic interactions. Current institutional interactions with positive effects on the management and governance are scarce, although several potential interactions may be developed. For the study area, any management action must recognize interferences from outside conditions and consider some of them (e.g., ecotourism management) as cross-cutting actions for the entire social-ecological system. We consider that institutional interactions and the development of social networks are opportunities to any collective effort aiming to improve governance of Islas Choros-Damas marine reserve. Communication of connections and interactions between marine protected areas and the wider social-ecological system (as described in this study) is proposed as a strategy to improve stakeholder participation in Chilean marine protected areas. PMID:24091586

  7. Interactions Between Spatially Explicit Conservation and Management Measures: Implications for the Governance of Marine Protected Areas

    NASA Astrophysics Data System (ADS)

    Cárcamo, P. Francisco; Gaymer, Carlos F.

    2013-12-01

    Marine protected areas are not established in an institutional and governance vacuum and managers should pay attention to the wider social-ecological system in which they are immersed. This article examines Islas Choros-Damas Marine Reserve, a small marine protected area located in a highly productive and biologically diverse coastal marine ecosystem in northern Chile, and the interactions between human, institutional, and ecological dimensions beyond those existing within its boundaries. Through documents analysis, surveys, and interviews, we described marine reserve implementation (governing system) and the social and natural ecosystem-to-be-governed. We analyzed the interactions and the connections between the marine reserve and other spatially explicit conservation and/or management measures existing in the area and influencing management outcomes and governance. A top-down approach with poor stakeholder involvement characterized the implementation process. The marine reserve is highly connected with other spatially explicit measures and with a wider social-ecological system through various ecological processes and socio-economic interactions. Current institutional interactions with positive effects on the management and governance are scarce, although several potential interactions may be developed. For the study area, any management action must recognize interferences from outside conditions and consider some of them (e.g., ecotourism management) as cross-cutting actions for the entire social-ecological system. We consider that institutional interactions and the development of social networks are opportunities to any collective effort aiming to improve governance of Islas Choros-Damas marine reserve. Communication of connections and interactions between marine protected areas and the wider social-ecological system (as described in this study) is proposed as a strategy to improve stakeholder participation in Chilean marine protected areas.

  8. Predator-prey interactions, resource depression and patch revisitation

    USGS Publications Warehouse

    Erwin, R.M.

    1989-01-01

    Generalist predators may be confronted by different types of prey in different patches: sedentary and conspicuous, cryptic (with or without refugia), conspicuous and nonsocial, or conspicuous and social. I argue that, where encounter rates with prey are of most importance, patch revisitation should be a profitable tactic where prey have short 'recovery' times (conspicuous, nonsocial prey), or where anti-predator response (e.g. shoaling) may increase conspicuousness. Predictions are made for how temporal changes in prey encounter rates should affect revisit schedules and feeding rates for the 4 different prey types.

  9. Testing the Prey-Trap Hypothesis at Two Wildlife Conservancies in Kenya.

    PubMed

    Dupuis-Desormeaux, Marc; Davidson, Zeke; Mwololo, Mary; Kisio, Edwin; Taylor, Sam; MacDonald, Suzanne E

    2015-01-01

    Protecting an endangered and highly poached species can conflict with providing an open and ecologically connected landscape for coexisting species. In Kenya, about half of the black rhino (Diceros bicornis) live in electrically fenced private conservancies. Purpose-built fence-gaps permit some landscape connectivity for elephant while restricting rhino from escaping. We monitored the usage patterns at these gaps by motion-triggered cameras and found high traffic volumes and predictable patterns of prey movement. The prey-trap hypothesis (PTH) proposes that predators exploit this predictable prey movement. We tested the PTH at two semi-porous reserves using two different methods: a spatial analysis and a temporal analysis. Using spatial analysis, we mapped the location of predation events with GPS and looked for concentration of kill sites near the gaps as well as conducting clustering and hot spot analysis to determine areas of statistically significant predation clustering. Using temporal analysis, we examined the time lapse between the passage of prey and predator and searched for evidence of active prey seeking and/or predator avoidance. We found no support for the PTH and conclude that the design of the fence-gaps is well suited to promoting connectivity in these types of conservancies. PMID:26489024

  10. Testing the Prey-Trap Hypothesis at Two Wildlife Conservancies in Kenya.

    PubMed

    Dupuis-Desormeaux, Marc; Davidson, Zeke; Mwololo, Mary; Kisio, Edwin; Taylor, Sam; MacDonald, Suzanne E

    2015-01-01

    Protecting an endangered and highly poached species can conflict with providing an open and ecologically connected landscape for coexisting species. In Kenya, about half of the black rhino (Diceros bicornis) live in electrically fenced private conservancies. Purpose-built fence-gaps permit some landscape connectivity for elephant while restricting rhino from escaping. We monitored the usage patterns at these gaps by motion-triggered cameras and found high traffic volumes and predictable patterns of prey movement. The prey-trap hypothesis (PTH) proposes that predators exploit this predictable prey movement. We tested the PTH at two semi-porous reserves using two different methods: a spatial analysis and a temporal analysis. Using spatial analysis, we mapped the location of predation events with GPS and looked for concentration of kill sites near the gaps as well as conducting clustering and hot spot analysis to determine areas of statistically significant predation clustering. Using temporal analysis, we examined the time lapse between the passage of prey and predator and searched for evidence of active prey seeking and/or predator avoidance. We found no support for the PTH and conclude that the design of the fence-gaps is well suited to promoting connectivity in these types of conservancies.

  11. Testing the Prey-Trap Hypothesis at Two Wildlife Conservancies in Kenya

    PubMed Central

    Dupuis-Desormeaux, Marc; Davidson, Zeke; Mwololo, Mary; Kisio, Edwin; Taylor, Sam; MacDonald, Suzanne E.

    2015-01-01

    Protecting an endangered and highly poached species can conflict with providing an open and ecologically connected landscape for coexisting species. In Kenya, about half of the black rhino (Diceros bicornis) live in electrically fenced private conservancies. Purpose-built fence-gaps permit some landscape connectivity for elephant while restricting rhino from escaping. We monitored the usage patterns at these gaps by motion-triggered cameras and found high traffic volumes and predictable patterns of prey movement. The prey-trap hypothesis (PTH) proposes that predators exploit this predictable prey movement. We tested the PTH at two semi-porous reserves using two different methods: a spatial analysis and a temporal analysis. Using spatial analysis, we mapped the location of predation events with GPS and looked for concentration of kill sites near the gaps as well as conducting clustering and hot spot analysis to determine areas of statistically significant predation clustering. Using temporal analysis, we examined the time lapse between the passage of prey and predator and searched for evidence of active prey seeking and/or predator avoidance. We found no support for the PTH and conclude that the design of the fence-gaps is well suited to promoting connectivity in these types of conservancies. PMID:26489024

  12. Developing measurement indices to enhance protection and resilience of U.S. critical infrastructure and key resources.

    SciTech Connect

    Fisher, R. E.; Norman, M.

    2010-07-01

    The US Department of Homeland Security (DHS) is developing indices to better assist in the risk management of critical infrastructures. The first of these indices is the Protective Measures Index - a quantitative index that measures overall protection across component categories: physical security, security management, security force, information sharing, protective measures and dependencies. The Protective Measures Index, which can also be recalculated as the Vulnerability Index, is a way to compare differing protective measures (eg fence versus security training). The second of these indices is the Resilience Index, which assesses a site's resilience and consists of three primary components: robustness, resourcefulness and recovery. The third index is the Criticality Index, which assesses the importance of a facility. The Criticality Index includes economic, human, governance and mass evacuation impacts. The Protective Measures Index, Resilience Index and Criticality Index are being developed as part of the Enhanced Critical Infrastructure Protection initiative that DHS protective security advisers implement across the nation at critical facilities. This paper describes two core themes: determination of the vulnerability, resilience and criticality of a facility and comparison of the indices at different facilities.

  13. Effects of prey quality and predator body size on prey DNA detection success in a centipede predator.

    PubMed

    Eitzinger, B; Unger, E M; Traugott, M; Scheu, S

    2014-08-01

    Predator body size and prey quality are important factors driving prey choice and consumption rates. Both factors might affect prey detection success in PCR-based gut content analysis, potentially resulting in over- or underestimation of feeding rates. Experimental evidence, however, is scarce. We examined how body size and prey quality affect prey DNA detection success in centipede predators. Due to metabolic rates increasing with body size, we hypothesized that prey DNA detection intervals will be shorter in large predators than in smaller ones. Moreover, we hypothesized that prey detection intervals of high-quality prey, defined by low carbon-to-nitrogen ratio will be shorter than in low-quality prey due to faster assimilation. Small, medium and large individuals of centipedes Lithobius spp. (Lithobiidae, Chilopoda) were fed Collembola and allowed to digest prey for up to 168 h post-feeding. To test our second hypothesis, medium-sized lithobiids were fed with either Diptera or Lumbricidae. No significant differences in 50% prey DNA detection success time intervals for a 272-bp prey DNA fragment were found between the predator size groups, indicating that body size does not affect prey DNA detection success. Post-feeding detection intervals were significantly shorter in Lumbricidae and Diptera compared to Collembola prey, apparently supporting the second hypothesis. However, sensitivity of diagnostic PCR differed between prey types, and quantitative PCR revealed that concentration of targeted DNA varied significantly between prey types. This suggests that both DNA concentration and assay sensitivity need to be considered when assessing prey quality effects on prey DNA detection success.

  14. Effects of prey quality and predator body size on prey DNA detection success in a centipede predator.

    PubMed

    Eitzinger, B; Unger, E M; Traugott, M; Scheu, S

    2014-08-01

    Predator body size and prey quality are important factors driving prey choice and consumption rates. Both factors might affect prey detection success in PCR-based gut content analysis, potentially resulting in over- or underestimation of feeding rates. Experimental evidence, however, is scarce. We examined how body size and prey quality affect prey DNA detection success in centipede predators. Due to metabolic rates increasing with body size, we hypothesized that prey DNA detection intervals will be shorter in large predators than in smaller ones. Moreover, we hypothesized that prey detection intervals of high-quality prey, defined by low carbon-to-nitrogen ratio will be shorter than in low-quality prey due to faster assimilation. Small, medium and large individuals of centipedes Lithobius spp. (Lithobiidae, Chilopoda) were fed Collembola and allowed to digest prey for up to 168 h post-feeding. To test our second hypothesis, medium-sized lithobiids were fed with either Diptera or Lumbricidae. No significant differences in 50% prey DNA detection success time intervals for a 272-bp prey DNA fragment were found between the predator size groups, indicating that body size does not affect prey DNA detection success. Post-feeding detection intervals were significantly shorter in Lumbricidae and Diptera compared to Collembola prey, apparently supporting the second hypothesis. However, sensitivity of diagnostic PCR differed between prey types, and quantitative PCR revealed that concentration of targeted DNA varied significantly between prey types. This suggests that both DNA concentration and assay sensitivity need to be considered when assessing prey quality effects on prey DNA detection success. PMID:24383982

  15. Functional response of wolves preying on barren-ground caribou in a multiple-prey ecosystem

    USGS Publications Warehouse

    Dale, B.W.; Adams, Layne G.; Bowyer, R.T.

    1994-01-01

    1. We investigated the functional response of wolves (Canis lupus) to varying abundance of ungulate prey to test the hypothesis that switching from alternate prey to preferred prey results in regulation of a caribou (Rangifer tarandus) population at low densities. 2. We determined prey selection, kill rates, and prey abundance for four wolf packs during three 30-day periods in March 1989, March 1990, November 1990, and created a simple discrete model to evaluate the potential for the expected numerical and observed functional responses of wolves to regulate caribou populations. 3. We observed a quickly decelerating type II functional response that, in the absence of numerical response, implicates an anti-regulatory effect of wolf predation on barren-ground caribou dynamics. 4. There was little potential for regulation caused by the multiplicative effect of increasing functional and numerical responses because of presence of alternative prey. This resulted in high wolf:caribou ratios at low prey densities which precluded the effects of an increasing functional response. 5. Inversely density-dependent predation by other predators, such as bears, reduces the potential for predators to regulate caribou populations at low densities, and small reductions in predation by one predator may have disproportionately large effects on the total predation rate.

  16. Predation risk increases dispersal distance in prey

    NASA Astrophysics Data System (ADS)

    Otsuki, Hatsune; Yano, Shuichi

    2014-06-01

    Understanding the ecological factors that affect dispersal distances allows us to predict the consequences of dispersal. Although predator avoidance is an important cause of prey dispersal, its effects on dispersal distance have not been investigated. We used simple experimental setups to test dispersal distances of the ambulatory dispersing spider mite ( Tetranychus kanzawai) in the presence or absence of a predator ( Neoseiulus womersleyi). In the absence of predators, most spider mites settled in adjacent patches, whereas the majority of those dispersing in the presence of predators passed through adjacent patches and settled in distant ones. This is the first study to experimentally demonstrate that predators induce greater dispersal distance in prey.

  17. Why are predator urines aversive to prey?

    PubMed

    Nolte, D L; Mason, J R; Epple, G; Aronov, E; Campbell, D L

    1994-07-01

    Predator odors often repel prey species. In the present experiments, we investigated whether changes in the diet of a predator, the coyote (Canis latrans) would affect the repellency of its urine. Furthermore, because predator odors have a high sulfur content, reflecting large amounts of meat in the diet, we investigated the contribution of sulfurous odors to repellency. Our results were consistent with the hypothesis that diet composition and sulfurous metabolites of meat digestion are important for the repellency of predator odors to potential prey.

  18. Collective dose as a performance measure for occupational radiation protection programs: Issues and recommendations

    SciTech Connect

    Strom, D.J.; Harty, R.; Hickey, E.E.; Martin, J.B.; Peffers, M.S.; Kathren, R.L.

    1998-07-01

    Collective dose is one of the performance measures used at many US Department of Energy (DOE) contractor facilities to quantitatively assess the objectives of the radiation protection program. It can also be used as a management tool to improve the program for keeping worker doses as low as reasonably achievable (ALARA). Collective dose is used here to mean the sum of all total effective dose equivalent values for all workers in a specified group over a specified time. It is often used as a surrogate estimate of radiological risk. In principle, improvements in radiation protection programs and procedures will result in reduction of collective dose, all other things being equal. Within the DOE, most frequently, a single collective dose number, which may or may not be adjusted for workload and other factors, is used as a performance measure for a contractor. The purpose of this report is to evaluate the use of collective dose as a performance measure for ALARA programs at DOE sites.

  19. Leopard frog priorities in choosing between prey at different locations.

    PubMed

    Dudkin, Elizabeth A; Peiffer, Teri; Burkitt, Benjamin; Neeb, Christopher N; Gruberg, Edward R

    2011-01-01

    Frogs are able to respond to a prey stimulus throughout their 360° ground-level visual field as well as in the superior visual field. We compared the likelihood of frogs choosing between a more nasally located, ground-level prey versus a more temporally located ground-level prey, when the prey at the nasal location is further away from the frog. Two crickets were presented simultaneously at 9 pairs of angles that included both crickets in the binocular visual field, both crickets in the monocular visual field, or one cricket in the binocular field and one in the monocular field. Frogs chose the more nasally located prey at least 71% of the time when the more temporal prey was in the monocular field; and 64% of the time when both prey were in the binocular field. Frogs tended to choose the more nasally located prey, even though it takes the frog longer to reach the prey. In addition, when given a choice between a prey located at ground level versus a prey located in the superior field, frogs tend to choose the prey at ground-level. These results suggest that there is a neural mechanism that biases frogs' responses to prey stimuli.

  20. Prey aggregation is an effective olfactory predator avoidance strategy.

    PubMed

    Johannesen, Asa; Dunn, Alison M; Morrell, Lesley J

    2014-01-01

    Predator-prey interactions have a major effect on species abundance and diversity, and aggregation is a well-known anti-predator behaviour. For immobile prey, the effectiveness of aggregation depends on two conditions: (a) the inability of the predator to consume all prey in a group and (b) detection of a single large group not being proportionally easier than that of several small groups. How prey aggregation influences predation rates when visual cues are restricted, such as in turbid water, has not been thoroughly investigated. We carried out foraging (predation) experiments using a fish predator and (dead) chironomid larvae as prey in both laboratory and field settings. In the laboratory, a reduction in visual cue availability (in turbid water) led to a delay in the location of aggregated prey compared to when visual cues were available. Aggregated prey suffered high mortality once discovered, leading to better survival of dispersed prey in the longer term. We attribute this to the inability of the dead prey to take evasive action. In the field (where prey were placed in feeding stations that allowed transmission of olfactory but not visual cues), aggregated (large groups) and semi-dispersed prey survived for longer than dispersed prey-including long term survival. Together, our results indicate that similar to systems where predators hunt using vision, aggregation is an effective anti-predator behaviour for prey avoiding olfactory predators.

  1. Measuring scatter radiation in diagnostic X rays for radiation protection purposes.

    PubMed

    Vlachos, Ioannis; Tsantilas, Xenophon; Kalyvas, Nektarios; Delis, Harry; Kandarakis, Ioannis; Panayiotakis, George

    2015-07-01

    During the last decades, radiation protection and dosimetry in medical X-ray imaging practice has been extensively studied. The purpose of this study was to measure secondary radiation in a conventional radiographic room, in terms of ambient dose rate equivalent H*(10) and its dependence on the radiographic exposure parameters such as X-ray tube voltage, tube current and distance. With some exceptions, the results indicated that the scattered radiation was uniform in the space around the water cylindrical phantom. The results also showed that the tube voltage and filtration affect the dose rate due to the scatter radiation. Finally, the scattered X-ray energy distribution was experimentally calculated.

  2. Stability and Hopf bifurcation in a diffusive predator-prey system incorporating a prey refuge.

    PubMed

    Chang, Xiaoyuan; Wei, Junjie

    2013-08-01

    A diffusive predator-prey model with Holling type II functional response and the no-flux boundary condition incorporating a constant prey refuge is considered. Globally asymptotically stability of the positive equilibrium is obtained. Regarding the constant number of prey refuge m as a bifurcation parameter, by analyzing the distribution of the eigenvalues, the existence of Hopf bifurcation is given. Employing the center manifold theory and normal form method, an algorithm for determining the properties of the Hopf bifurcation is derived. Some numerical simulations for illustrating the analysis results are carried out.

  3. Prey escaping wolves, Canis lupus, despite close proximity

    USGS Publications Warehouse

    Nelson, M.E.; Mech, L.D.

    1993-01-01

    We describe attacks by wolf (Canis lupus) packs in Minnesota on a white-tailed deer (Odocoileus virginianus) and a moose (Alces alces) in which wolves were within contact distance of the prey but in which the prey escaped.

  4. A single predator charging a herd of prey: effects of self volume and predator–prey decision-making

    NASA Astrophysics Data System (ADS)

    Schwarzl, Maria; Godec, Aljaz; Oshanin, Gleb; Metzler, Ralf

    2016-06-01

    We study the degree of success of a single predator hunting a herd of prey on a two-dimensional square lattice landscape. We explicitly consider the self volume of the prey restraining their dynamics on the lattice. The movement of both predator and prey is chosen to include an intelligent, decision making step based on their respective sighting ranges, the radius in which they can detect the other species (prey cannot recognise each other besides the self volume interaction): after spotting each other the motion of prey and predator turns from a nearest neighbour random walk into directed escape or chase, respectively. We consider a large range of prey densities and sighting ranges and compute the mean first passage time for a predator to catch a prey as well as characterise the effective dynamics of the hunted prey. We find that the prey's sighting range dominates their life expectancy and the predator profits more from a bad eyesight of the prey than from his own good eye sight. We characterise the dynamics in terms of the mean distance between the predator and the nearest prey. It turns out that effectively the dynamics of this distance coordinate can be captured in terms of a simple Ornstein–Uhlenbeck picture. Reducing the many-body problem to a simple two-body problem by imagining predator and nearest prey to be connected by an effective Hookean bond, all features of the model such as prey density and sighting ranges merge into the effective binding constant.

  5. A single predator charging a herd of prey: effects of self volume and predator-prey decision-making

    NASA Astrophysics Data System (ADS)

    Schwarzl, Maria; Godec, Aljaz; Oshanin, Gleb; Metzler, Ralf

    2016-06-01

    We study the degree of success of a single predator hunting a herd of prey on a two-dimensional square lattice landscape. We explicitly consider the self volume of the prey restraining their dynamics on the lattice. The movement of both predator and prey is chosen to include an intelligent, decision making step based on their respective sighting ranges, the radius in which they can detect the other species (prey cannot recognise each other besides the self volume interaction): after spotting each other the motion of prey and predator turns from a nearest neighbour random walk into directed escape or chase, respectively. We consider a large range of prey densities and sighting ranges and compute the mean first passage time for a predator to catch a prey as well as characterise the effective dynamics of the hunted prey. We find that the prey's sighting range dominates their life expectancy and the predator profits more from a bad eyesight of the prey than from his own good eye sight. We characterise the dynamics in terms of the mean distance between the predator and the nearest prey. It turns out that effectively the dynamics of this distance coordinate can be captured in terms of a simple Ornstein-Uhlenbeck picture. Reducing the many-body problem to a simple two-body problem by imagining predator and nearest prey to be connected by an effective Hookean bond, all features of the model such as prey density and sighting ranges merge into the effective binding constant.

  6. Blue whales (Balaenoptera musculus) optimize foraging efficiency by balancing oxygen use and energy gain as a function of prey density

    PubMed Central

    Hazen, Elliott Lee; Friedlaender, Ari Seth; Goldbogen, Jeremy Arthur

    2015-01-01

    Terrestrial predators can modulate the energy used for prey capture to maximize efficiency, but diving animals face the conflicting metabolic demands of energy intake and the minimization of oxygen depletion during a breath hold. It is thought that diving predators optimize their foraging success when oxygen use and energy gain act as competing currencies, but this hypothesis has not been rigorously tested because it has been difficult to measure the quality of prey that is targeted by free-ranging animals. We used high-resolution multisensor digital tags attached to foraging blue whales (Balaenoptera musculus) with concurrent acoustic prey measurements to quantify foraging performance across depth and prey density gradients. We parameterized two competing physiological models to estimate energy gain and expenditure based on foraging decisions. Our analyses show that at low prey densities, blue whale feeding rates and energy intake were low to minimize oxygen use, but at higher prey densities feeding frequency increased to maximize energy intake. Contrary to previous paradigms, we demonstrate that blue whales are not indiscriminate grazers but instead switch foraging strategies in response to variation in prey density and depth to maximize energetic efficiency. PMID:26601290

  7. Blue whales (Balaenoptera musculus) optimize foraging efficiency by balancing oxygen use and energy gain as a function of prey density.

    PubMed

    Hazen, Elliott Lee; Friedlaender, Ari Seth; Goldbogen, Jeremy Arthur

    2015-10-01

    Terrestrial predators can modulate the energy used for prey capture to maximize efficiency, but diving animals face the conflicting metabolic demands of energy intake and the minimization of oxygen depletion during a breath hold. It is thought that diving predators optimize their foraging success when oxygen use and energy gain act as competing currencies, but this hypothesis has not been rigorously tested because it has been difficult to measure the quality of prey that is targeted by free-ranging animals. We used high-resolution multisensor digital tags attached to foraging blue whales (Balaenoptera musculus) with concurrent acoustic prey measurements to quantify foraging performance across depth and prey density gradients. We parameterized two competing physiological models to estimate energy gain and expenditure based on foraging decisions. Our analyses show that at low prey densities, blue whale feeding rates and energy intake were low to minimize oxygen use, but at higher prey densities feeding frequency increased to maximize energy intake. Contrary to previous paradigms, we demonstrate that blue whales are not indiscriminate grazers but instead switch foraging strategies in response to variation in prey density and depth to maximize energetic efficiency. PMID:26601290

  8. Blue whales (Balaenoptera musculus) optimize foraging efficiency by balancing oxygen use and energy gain as a function of prey density.

    PubMed

    Hazen, Elliott Lee; Friedlaender, Ari Seth; Goldbogen, Jeremy Arthur

    2015-10-01

    Terrestrial predators can modulate the energy used for prey capture to maximize efficiency, but diving animals face the conflicting metabolic demands of energy intake and the minimization of oxygen depletion during a breath hold. It is thought that diving predators optimize their foraging success when oxygen use and energy gain act as competing currencies, but this hypothesis has not been rigorously tested because it has been difficult to measure the quality of prey that is targeted by free-ranging animals. We used high-resolution multisensor digital tags attached to foraging blue whales (Balaenoptera musculus) with concurrent acoustic prey measurements to quantify foraging performance across depth and prey density gradients. We parameterized two competing physiological models to estimate energy gain and expenditure based on foraging decisions. Our analyses show that at low prey densities, blue whale feeding rates and energy intake were low to minimize oxygen use, but at higher prey densities feeding frequency increased to maximize energy intake. Contrary to previous paradigms, we demonstrate that blue whales are not indiscriminate grazers but instead switch foraging strategies in response to variation in prey density and depth to maximize energetic efficiency.

  9. Distinguishing the impacts of inadequate prey and vessel traffic on an endangered killer whale (Orcinus orca) population.

    PubMed

    Ayres, Katherine L; Booth, Rebecca K; Hempelmann, Jennifer A; Koski, Kari L; Emmons, Candice K; Baird, Robin W; Balcomb-Bartok, Kelley; Hanson, M Bradley; Ford, Michael J; Wasser, Samuel K

    2012-01-01

    Managing endangered species often involves evaluating the relative impacts of multiple anthropogenic and ecological pressures. This challenge is particularly formidable for cetaceans, which spend the majority of their time underwater. Noninvasive physiological approaches can be especially informative in this regard. We used a combination of fecal thyroid (T3) and glucocorticoid (GC) hormone measures to assess two threats influencing the endangered southern resident killer whales (SRKW; Orcinus orca) that frequent the inland waters of British Columbia, Canada and Washington, U.S.A. Glucocorticoids increase in response to nutritional and psychological stress, whereas thyroid hormone declines in response to nutritional stress but is unaffected by psychological stress. The inadequate prey hypothesis argues that the killer whales have become prey limited due to reductions of their dominant prey, Chinook salmon (Oncorhynchus tshawytscha). The vessel impact hypothesis argues that high numbers of vessels in close proximity to the whales cause disturbance via psychological stress and/or impaired foraging ability. The GC and T3 measures supported the inadequate prey hypothesis. In particular, GC concentrations were negatively correlated with short-term changes in prey availability. Whereas, T3 concentrations varied by date and year in a manner that corresponded with more long-term prey availability. Physiological correlations with prey overshadowed any impacts of vessels since GCs were lowest during the peak in vessel abundance, which also coincided with the peak in salmon availability. Our results suggest that identification and recovery of strategic salmon populations in the SRKW diet are important to effectively promote SRKW recovery.

  10. Dependence of Measured Lateral Stress on Thickness of Protective ``Padding'' around Gauge

    NASA Astrophysics Data System (ADS)

    Hammond, R. I.; Church, P. D.; Grief, A.; Proud, W. G.; Field, J. E.

    2004-07-01

    Earlier work found that lateral stress gauges were unusable when the longitudinal stress in the sample exceeded around 13 GPa in samples of steel. This pressure corresponds to a phase transition found in iron and its alloys. It was hoped that protective padding would allow measurement of stresses higher than this. It was therefore necessary to investigate the effect of the padding on the stress measured. A series of experiments were carried out using mild steel with different thicknesses of mylar or polycarbonate padding. This research has been supported by simulation studies using the Eulerian hydrocode GRIM, which has indicated some issues with the representation of the lateral gauge in the hydrocode. The simulations have confirmed the experimental trends observed with additional padding, but they have also indicated the potential need for additional analysis on the raw lateral gauge data.

  11. Diet, prey delivery rates, and prey biomass of Northern Goshawks in East-Central Arizona

    USGS Publications Warehouse

    Rogers, A.S.; DeStefano, S.; Ingraldi, M.F.

    2006-01-01

    Recent concern over persistence of Northern Goshawk (Accipiter gentilis) populations in Arizona has stemmed from two long-term demography studies that report substantial yearly fluctuations in productivity and evidence of a declining population. Although many factors could be involved in changes in productivity and population declines, availability of food is one such factor. As part of a demography study on the Sitgreaves portion of the Apache-Sitgreaves National Forest in Arizona, we used remote cameras to assess diets of goshawks. Northern Goshawks preyed upon 22 species during two nesting seasons. Adult pairs tended to specialize on particular species of prey. Prey delivery rates decreased throughout the nesting season with a corresponding increase in biomass in the latter stages of the nestling and fledgling periods. Adults appeared to take larger prey as nestlings increased in age.

  12. Prey aggregation is an effective olfactory predator avoidance strategy

    PubMed Central

    Dunn, Alison M.; Morrell, Lesley J.

    2014-01-01

    Predator–prey interactions have a major effect on species abundance and diversity, and aggregation is a well-known anti-predator behaviour. For immobile prey, the effectiveness of aggregation depends on two conditions: (a) the inability of the predator to consume all prey in a group and (b) detection of a single large group not being proportionally easier than that of several small groups. How prey aggregation influences predation rates when visual cues are restricted, such as in turbid water, has not been thoroughly investigated. We carried out foraging (predation) experiments using a fish predator and (dead) chironomid larvae as prey in both laboratory and field settings. In the laboratory, a reduction in visual cue availability (in turbid water) led to a delay in the location of aggregated prey compared to when visual cues were available. Aggregated prey suffered high mortality once discovered, leading to better survival of dispersed prey in the longer term. We attribute this to the inability of the dead prey to take evasive action. In the field (where prey were placed in feeding stations that allowed transmission of olfactory but not visual cues), aggregated (large groups) and semi-dispersed prey survived for longer than dispersed prey—including long term survival. Together, our results indicate that similar to systems where predators hunt using vision, aggregation is an effective anti-predator behaviour for prey avoiding olfactory predators. PMID:24918032

  13. Transient dynamics and the destabilizing effects of prey heterogeneity.

    PubMed

    Steiner, Christopher F; Klausmeier, Christopher A; Litchman, Elena

    2012-03-01

    The presence of prey heterogeneity and weakly interacting prey species is frequently viewed as a stabilizer of predator-prey dynamics, countering the destabilizing effects of enrichment and reducing the amplitude of population cycles. However, prior model explorations have largely focused on long-term, dynamic attractors rather than transient dynamics. Recent theoretical work shows that the presence of prey that are defended from predation can have strongly divergent effects on dynamics depending on time scale: prey heterogeneity can counteract the destabilizing effects of enrichment on predator-prey dynamics at long time scales but strongly destabilize systems during transient phases by creating long periods of low predator/prey abundance and increasing extinction probability (an effect that is amplified with increasing enrichment). We tested these general predictions using a planktonic system composed of a zooplankton predator and multiple algal prey. We first parameterized a model of our system to generate predictions and tested these experimentally. Our results qualitatively supported several model predictions. During transient phases, presence of defended algal prey increased predator extinctions at low and high enrichment levels compared to systems with only a single edible prey. This destabilizing effect was moderated at higher dilution rates, as predicted by our model. When examining dynamics beyond initial oscillations, presence of the defended prey increased predator-prey temporal variability at high nutrient enrichment but had no effect at low nutrient levels. Our results highlight the importance of considering transient dynamics when assessing the role of stabilizing factors on the dynamics of food webs.

  14. Molecular assessment of heterotrophy and prey digestion in zooxanthellate cnidarians.

    PubMed

    Leal, M C; Nejstgaard, J C; Calado, R; Thompson, M E; Frischer, M E

    2014-08-01

    Zooxanthellate cnidarians are trophically complex, relying on both autotrophy and heterotrophy. Although several aspects of heterotrophy have been studied in these organisms, information linking prey capture with digestion is still missing. We used prey-specific PCR-based tools to assess feeding and prey digestion of two zooxanthellate cnidarians - the tropical sea anemone Aiptasia sp. and the scleractinian coral Oculina arbuscula. Prey DNA disappeared rapidly for the initial 1-3 days, whereas complete digestion of prey DNA required up to 10 days in O. arbuscula and 5 or 6 days in Aiptasia sp. depending on prey species. These digestion times are considerably longer than previously reported from microscopy-based examination of zooxanthellate cnidarians and prey DNA breakdown in other marine invertebrates, but similar to prey DNA breakdown reported from terrestrial invertebrates such as heteroptera and spiders. Deprivation of external prey induced increased digestion rates during the first days after feeding in O. arbuscula, but after 6 days of digestion, there were no differences in the remaining prey levels in fed and unfed corals. This study indicates that prey digestion by symbiotic corals may be slower than previously reported and varies with the type of prey, the cnidarian species and its feeding history. These observations have important implications for bioenergetic and trophodynamic studies on zooxanthellate cnidarians.

  15. Discontinuous locomotion and prey sensing in the leech.

    PubMed

    Harley, Cynthia M; Rossi, Matthew; Cienfuegos, Javier; Wagenaar, Daniel

    2013-05-15

    The medicinal leech, Hirudo verbana, is an aquatic predator that utilizes water waves to locate its prey. However, to reach their prey, the leeches must move within the same water that they are using to sense prey. This requires that they either move ballistically towards a pre-determined prey location or that they account for their self-movement and continually track prey. We found that leeches do not localize prey ballistically. Instead, they require continual sensory information to track their prey. Indeed, in the event that the prey moves, leeches will approach the prey's new location. While leeches need to continually sense water disturbances to update their percept of prey location, their own behavior is discontinuous--prey involves switching between swimming, crawling and non-locomoting. Each of these behaviors may allow for different sensory capabilities and may require different sensory filters. Here, we examined the sensory capabilities of leeches during each of these behaviors. We found that while one could expect the non-locomoting phases to direct subsequent behaviors, crawling phases were more effective than non-locomotor phases for providing direction. During crawling bouts, leeches adjusted their heading so as to become more directed towards the stimulus. This was not observed during swimming. Furthermore, in the presence of prey-like stimuli, leeches crawled more often and for longer periods of time.

  16. Insect prey characteristics affecting regional variation in chimpanzee tool use.

    PubMed

    Sanz, Crickette M; Deblauwe, Isra; Tagg, Nikki; Morgan, David B

    2014-06-01

    It is an ongoing interdisciplinary pursuit to identify the factors shaping the emergence and maintenance of tool technology. Field studies of several primate taxa have shown that tool using behaviors vary within and between populations. While similarity in tools over spatial and temporal scales may be the product of socially learned skills, it may also reflect adoption of convergent strategies that are tailored to specific prey features. Much has been claimed about regional variation in chimpanzee tool use, with little attention to the ecological circumstances that may have shaped such differences. This study examines chimpanzee tool use in termite gathering to evaluate the extent to which the behavior of insect prey may dictate chimpanzee technology. More specifically, we conducted a systematic comparison of chimpanzee tool use and termite prey between the Goualougo Triangle in the Republic of Congo and the La Belgique research site in southeast Cameroon. Apes at both of these sites are known to use tool sets to gather several species of termites. We collected insect specimens and measured the characteristics of their nests. Associated chimpanzee tool assemblages were documented at both sites and video recordings were conducted in the Goualougo Triangle. Although Macrotermitinae assemblages were identical, we found differences in the tools used to gather these termites. Based on measurements of the chimpanzee tools and termite nests at each site, we concluded that some characteristics of chimpanzee tools were directly related to termite nest structure. While there is a certain degree of uniformity within approaches to particular tool tasks across the species range, some aspects of regional variation in hominoid technology are likely adaptations to subtle environmental differences between populations or groups. Such microecological differences between sites do not negate the possibility of cultural transmission, as social learning may be required to transmit

  17. Alterations in prey capture and induction of metallothioneins in grass shrimp fed cadmium-contaminated prey

    SciTech Connect

    Wallace, W.G.; Hoexum Brouwer, T.M.; Brouwer, M.; Lopez, G.R.

    2000-04-01

    The aquatic oligochaete Limnodrilus hoffmeisteri from a Cd-contaminated cove on the Hudson River, Foundry Cove, New York, USA, has evolved Cd resistance. Past studies have focused on how the mode of detoxification of Cd by these Cd-resistant worms influences Cd trophic transfer to the grass shrimp Palaemonetes pugio. In the present study, the authors investigate reductions in prey capture in grass shrimp fed Cd-contaminated prey. They also investigate the induction of metal-binding proteins, metallothioneins, in these Cd-exposed shrimp. Grass shrimp were fed field-exposed Cd-contaminated Foundry Cove oligochaetes or laboratory-exposed Cd-contaminated Artemia salina. Following these exposures, the ability of Cd- dosed and control shrimp to capture live A. salina was compared. Results show that shrimp fed laboratory-exposed Cd-contaminated A. salina for 2 weeks exhibit significant reductions in their ability to successfully capture prey (live A. salina). Reductions in prey capture were also apparent, though not as dramatic in shrimp fed for 1 week on field-exposed Cd-contained Foundry Cove oligochaetes. Shrimp were further investigated for their subcellular distribution of Cd to examine if alterations in prey capture could be linked to saturation of Cd-metallothionein. Cd-dosed shrimp produced a low molecular weight CD-binding metallothionein protein in a dose- and time-dependent manner. Most importantly, successful prey capture decreased with increased Cd body burdens and increased Cd concentration bound to high molecular weight proteins.

  18. A predator-prey model with diseases in both prey and predator

    NASA Astrophysics Data System (ADS)

    Gao, Xubin; Pan, Qiuhui; He, Mingfeng; Kang, Yibin

    2013-12-01

    In this paper, we present and analyze a predator-prey model, in which both predator and prey can be infected. Each of the predator and prey is divided into two categories, susceptible and infected. The epidemics cannot be transmitted between prey and predator by predation. The predation ability of susceptible predators is stronger than infected ones. Likewise, it is more difficult to catch a susceptible prey than an infected one. And the diseases cannot be hereditary in both of the predator and prey populations. Based on the assumptions above, we find that there are six equilibrium points in this model. Using the base reproduction number, we discuss the stability of the equilibrium points qualitatively. Then both of the local and global stabilities of the equilibrium points are analyzed quantitatively by mathematical methods. We provide numerical results to discuss some interesting biological cases that our model exhibits. Lastly, we discuss how the infectious rates affect the stability, and how the other parameters work in the five possible cases within this model.

  19. Examining the potential for nutritional stress in young Steller sea lions: physiological effects of prey composition.

    PubMed

    Rosen, David A S; Trites, Andrew W

    2005-05-01

    The effects of high- and low-lipid prey on the body mass, body condition, and metabolic rates of young captive Steller sea lions (Eumetopias jubatus) were examined to better understand how changes in prey composition might impact the physiology and health of wild sea lions and contribute to their population decline. Results of three feeding experiments suggest that prey lipid content did not significantly affect body mass or relative body condition (lipid mass as a percent of total mass) when sea lions could consume sufficient prey to meet their energy needs. However, when energy intake was insufficient to meet daily requirements, sea lions lost more lipid mass (9.16+/-1.80 kg+/-SE) consuming low-lipid prey compared with eating high-lipid prey (6.52+/-1.65 kg). Similarly, the sea lions lost 2.7+/-0.9 kg of lipid mass while consuming oil-supplemented pollock at maintenance energy levels but gained 5.2+/-2.7 kg lipid mass while consuming identical energetic levels of herring. Contrary to expectations, there was a 9.7+/-1.8% increase in metabolism during mass loss on submaintenance diets. Relative body condition decreased only 3.7+/-3.8% during periods of imposed nutritional stress, despite a 10.4+/-4.8% decrease in body mass. These findings raise questions regarding the efficacy of measures of relative body condition to detect such changes in nutritional status among wild animals. The results of these three experiments suggest that prey composition can have additional effects on sea lion energy stores beyond the direct effects of insufficient energy intake. PMID:15900507

  20. PHITS simulations of the Protective curtain experiment onboard the Service module of ISS: Comparison with absorbed doses measured with TLDs

    NASA Astrophysics Data System (ADS)

    Ploc, Ondřej; Sihver, Lembit; Kartashov, Dmitry; Shurshakov, Vyacheslav; Tolochek, Raisa

    2013-12-01

    "Protective curtain" was the physical experiment onboard the International Space Station (ISS) aimed on radiation measurement of the dose - reducing effect of the additional shielding made of hygienic water-soaked wipes and towels placed on the wall in the crew cabin of the Service module Zvezda. The measurements were performed with 12 detector packages composed of thermoluminescent detectors (TLDs) and plastic nuclear track detectors (PNTDs) placed at the Protective curtain, so that they created pairs of shielded and unshielded detectors.

  1. Arthropod prey for riparian associated birds in headwater forests of the Oregon Coast Range

    USGS Publications Warehouse

    Hagar, Joan C.; Li, Judith; Sobota, Janel; Jenkins, Stephanie

    2012-01-01

    Headwater riparian areas occupy a large proportion of the land base in Pacific Northwest forests, and thus are ecologically and economically important. Although a primary goal of management along small headwater streams is the protection of aquatic resources, streamside habitat also is important for many terrestrial wildlife species. However, mechanisms underlying the riparian associations of some terrestrial species have not been well studied, particularly for headwater drainages. We investigated the diets of and food availability for four bird species associated with riparian habitats in montane coastal forests of western Oregon, USA. We examined variation in the availability of arthropod prey as a function of distance from stream. Specifically, we tested the hypotheses that (1) emergent aquatic insects were a food source for insectivorous birds in headwater riparian areas, and (2) the abundances of aquatic and terrestrial arthropod prey did not differ between streamside and upland areas during the bird breeding season. We found that although adult aquatic insects were available for consumption throughout the study period, they represented a relatively small proportion of available prey abundance and biomass and were present in only 1% of the diet samples from only one of the four riparian-associated bird species. Nonetheless, arthropod prey, comprised primarily of insects of terrestrial origin, was more abundant in streamside than upland samples. We conclude that food resources for birds in headwater riparian areas are primarily associated with terrestrial vegetation, and that bird distributions along the gradient from streamside to upland may be related to variation in arthropod prey availability. Because distinct vegetation may distinguish riparian from upland habitats for riparian-associated birds and their terrestrial arthropod prey, we suggest that understory communities be considered when defining management zones for riparian habitat.

  2. Neutron Measurements for Radiation Protection in Low Earth Orbit - History and Future

    NASA Technical Reports Server (NTRS)

    Golightly, M. J.; Se,pmes. E/

    2003-01-01

    The neutron environment inside spacecraft has been of interest from a scientific and radiation protection perspective since early in the history of manned spaceflight. With 1:.1e exception of a few missions which carried plutonium-fueled radioisotope thermoelectric generators, all of the neutrons inside the spacecraft are secondary radiations resulting from interactions of high-energy charged particles with nuclei in the Earth's atmosphere, spacecraft structural materials, and the astronaut's own bodies. Although of great interest, definitive measurements of the spacecraft neutron field have been difficult due to the wide particle energy range and the limited available volume and power for traditional techniques involving Bonner spheres. A multitude of measurements, however, have been made of the neutron environment inside spacecraft. The majority of measurements were made using passive techniques including metal activation fo ils, fission foils, nuclear photoemulsions, plastic track detectors, and thermoluminescent detectors. Active measurements have utilized proton recoil spectrometers (stilbene), Bonner Spheres eRe proportional counter based), and LiI(Eu)phoswich scintillation detectors. For the International Space Station (ISS), only the plastic track! thermoluminescent detectors are used with any regularity. A monitoring program utilizing a set of active Bonner spheres was carried out in the ISS Lab module from March - December 200l. These measurements provide a very limited look at the crew neutron exposure, both in time coverage and neutron energy coverage. A review of the currently published data from past flights will be made and compared with the more recent results from the ISS. Future measurement efforts using currently available techniques and those in development will be also discussed.

  3. Evaluation of the implementation of radiation protection measures for aircrew in EU member states.

    PubMed

    Thierfeldt, S; Haider, C; Hans, P; Kaleve, M; Neuenfeldt, F

    2009-10-01

    An evaluation of the implementation of radiation protection measures for aircrew in EU Member States has recently been performed in a study sponsored by the European Commission. A comprehensive database has been gathered using questionnaires for civil aviation authorities, aircraft operators and radiation protection authorities in each country. The study has revealed the following results: all countries within the scope of this study where aircrew might receive annual doses >1 mSv have implemented appropriate legislation. The treatment of limits or constraints (action levels) for annual doses of 1, 6, 20 mSv could be an area where clear guidance by the European Commission might be needed. The way in which doses are determined might also be treated in a more harmonized way in the EU, including the transfer of dose data of freelancers or crew members working for other airlines. The establishment of the European Aviation Safety Agency leads to a gradual shift in responsibilities from the national civil aviation authorities towards this centralised European agency. Currently, however, tracking of doses for aircrew still lies with national bodies.

  4. Active foraging for toxic prey during gestation in a snake with maternal provisioning of sequestered chemical defences

    PubMed Central

    Kojima, Yosuke; Mori, Akira

    2015-01-01

    Many animals sequester dietary defensive compounds and incorporate them into the offspring, which protects the young against predation. One possible but poorly investigated question is whether females of such species actively prey upon toxic diets. The snake Rhabdophis tigrinus sequesters defensive steroids from toads consumed as prey; it also feeds on other amphibians. Females produce chemically armed offspring in direct proportion to their own level of toad-derived toxins by provisioning the toxins to their eggs. Our field observations of movements and stomach contents of radio-tracked R. tigrinus showed that gravid snakes preyed upon toads by actively foraging in the habitat of toads, even though toads were a scarce resource and toad-searching may incur potential costs. Our Y-maze experiments demonstrated that gravid females were more likely to trail the chemical cues of toads than were males or non-gravid females. These results showed behavioural switching in females and active foraging for scarce, toxic prey during gestation. Because exploitation of toads by gravid females results in their offspring being more richly endowed with prey-derived toxins, active foraging for toxic prey is expected to be an adaptive antipredator trait, which may enhance chemical defence in offspring. PMID:25392472

  5. United States Environmental Protection Agency Fourier transform infrared spectroscopy test program for emissions measurement

    SciTech Connect

    Lay, L.T.

    1994-12-31

    The US Environmental Protection Agency (EPA) published amendments to the Clean Air Act (CAA) November 15, 1990. Title 3 of the CAA amendments included a list of 189 hazardous air pollutants (HAPs) for which emission test procedures must be established. An extractive emission test method, using Fourier Transform Infrared (FTIR) spectroscopy, is being developed for measuring HAP compounds. The FTIR procedure has the potential to detect over 100 of the listed compounds plus additional compounds such as criteria pollutants. This procedure has the ability to detect multiple compounds simultaneously and will provide near real-time data. Since the development of the extractive FTIR procedure, many source categories have been screened for HAP emissions using this technique. Modifications to the procedure have been made and validation testing has been performed. Currently, this technique is being used to collect data for maximum achievable control technology (MACT) standard development.

  6. Body size matters for aposematic prey during predator aversion learning.

    PubMed

    Smith, Karen E; Halpin, Christina G; Rowe, Candy

    2014-11-01

    Aposematic prey advertise their toxicity to predators using conspicuous warning signals, which predators learn to use to reduce their intake of toxic prey. Like other types of prey, aposematic prey often differ in body size, both within and between species. Increasing body size can increase signal size, which make larger aposematic prey more detectable but also gives them a more effective and salient deterrent. However, increasing body size also increases the nutritional value of prey, and larger aposematic prey may make a more profitable meal to predators that are trading off the costs of eating toxins with the benefits of ingesting nutrients. We tested if body size, independent of signal size, affected predation of toxic prey as predators learn to reduce their attacks on them. European starlings (Sturnus vulgaris) learned to discriminate between defended (quinine-injected) and undefended (water-injected) mealworm prey (Tenebrio molitor) using visual signals. During this process, we found that birds attacked and ate more defended prey the larger they were. Body size does affect the probability that toxic prey are attacked and eaten, which has implications for the evolutionary dynamics of aposematism and mimicry (where species share the same warning pattern). PMID:25256160

  7. Intense or Spatially Heterogeneous Predation Can Select against Prey Dispersal

    PubMed Central

    Barraquand, Frederic; Murrell, David J.

    2012-01-01

    Dispersal theory generally predicts kin competition, inbreeding, and temporal variation in habitat quality should select for dispersal, whereas spatial variation in habitat quality should select against dispersal. The effect of predation on the evolution of dispersal is currently not well-known: because predation can be variable in both space and time, it is not clear whether or when predation will promote dispersal within prey. Moreover, the evolution of prey dispersal affects strongly the encounter rate of predator and prey individuals, which greatly determines the ecological dynamics, and in turn changes the selection pressures for prey dispersal, in an eco-evolutionary feedback loop. When taken all together the effect of predation on prey dispersal is rather difficult to predict. We analyze a spatially explicit, individual-based predator-prey model and its mathematical approximation to investigate the evolution of prey dispersal. Competition and predation depend on local, rather than landscape-scale densities, and the spatial pattern of predation corresponds well to that of predators using restricted home ranges (e.g. central-place foragers). Analyses show the balance between the level of competition and predation pressure an individual is expected to experience determines whether prey should disperse or stay close to their parents and siblings, and more predation selects for less prey dispersal. Predators with smaller home ranges also select for less prey dispersal; more prey dispersal is favoured if predators have large home ranges, are very mobile, and/or are evenly distributed across the landscape. PMID:22247764

  8. Forest type affects prey foraging of saddleback tamarins, Saguinus nigrifrons.

    PubMed

    Kupsch, Denis; Waltert, Matthias; Heymann, Eckhard W

    2014-07-01

    Callitrichids can persist in secondary forests where they may benefit from elevated prey abundance. However, how tamarins forage for prey in secondary forest compared to primary forest has not been examined. Using scan and focal sampling, we compared prey foraging and capture success of two groups of Saguinus nigrifrons in north-eastern Peru: one ranging in primary forest, the other with access to a 10-year-old anthropogenic secondary forest. There was a trend for more prey search in the secondary forest, but prey feeding, capture success and size were lower compared to the primary forest. Tamarins avoided the forest floor, used vertical supports less often and searched on a lower variety of substrates in the secondary forest. In the secondary forest, tamarins did not capture flushed prey, which make up a substantial part of the total prey captures biomass in primary forests. Reduced prey capture success is unlikely to reflect reduced prey availability, since more Orthoptera were found in secondary forest through ultrasonic surveys. Therefore, the prey search activity of S. nigrifrons in young secondary forests seemed rather opportunistic, presumably influenced by altered predation patterns, vegetation structure, as well as prey diversity.

  9. Modelled three-dimensional suction accuracy predicts prey capture success in three species of centrarchid fishes.

    PubMed

    Kane, Emily A; Higham, Timothy E

    2014-06-01

    Prey capture is critical for survival, and differences in correctly positioning and timing a strike (accuracy) are likely related to variation in capture success. However, an ability to quantify accuracy under natural conditions, particularly for fishes, is lacking. We developed a predictive model of suction hydrodynamics and applied it to natural behaviours using three-dimensional kinematics of three centrarchid fishes capturing evasive and non-evasive prey. A spheroid ingested volume of water (IVW) with dimensions predicted by peak gape and ram speed was verified with known hydrodynamics for two species. Differences in capture success occurred primarily with evasive prey (64-96% success). Micropterus salmoides had the greatest ram and gape when capturing evasive prey, resulting in the largest and most elongate IVW. Accuracy predicted capture success, although other factors may also be important. The lower accuracy previously observed in M. salmoides was not replicated, but this is likely due to more natural conditions in our study. Additionally, we discuss the role of modulation and integrated behaviours in shaping the IVW and determining accuracy. With our model, accuracy is a more accessible performance measure for suction-feeding fishes, which can be used to explore macroevolutionary patterns of prey capture evolution. PMID:24718455

  10. Estimating Mercury Exposure of Piscivorous Birds and Sport Fish Using Prey Fish Monitoring.

    PubMed

    Ackerman, Joshua T; Hartman, C Alex; Eagles-Smith, Collin A; Herzog, Mark P; Davis, Jay; Ichikawa, Gary; Bonnema, Autumn

    2015-11-17

    Methylmercury is a global pollutant of aquatic ecosystems, and monitoring programs need tools to predict mercury exposure of wildlife. We developed equations to estimate methylmercury exposure of piscivorous birds and sport fish using mercury concentrations in prey fish. We collected original data on western grebes (Aechmophorus occidentalis) and Clark's grebes (Aechmophorus clarkii) and summarized the published literature to generate predictive equations specific to grebes and a general equation for piscivorous birds. We measured mercury concentrations in 354 grebes (blood averaged 1.06 ± 0.08 μg/g ww), 101 grebe eggs, 230 sport fish (predominantly largemouth bass and rainbow trout), and 505 prey fish (14 species) at 25 lakes throughout California. Mercury concentrations in grebe blood, grebe eggs, and sport fish were strongly related to mercury concentrations in prey fish among lakes. Each 1.0 μg/g dw (∼0.24 μg/g ww) increase in prey fish resulted in an increase in mercury concentrations of 103% in grebe blood, 92% in grebe eggs, and 116% in sport fish. We also found strong correlations between mercury concentrations in grebes and sport fish among lakes. Our results indicate that prey fish monitoring can be used to estimate mercury exposure of piscivorous birds and sport fish when wildlife cannot be directly sampled. PMID:26449260

  11. Estimating Mercury Exposure of Piscivorous Birds and Sport Fish Using Prey Fish Monitoring.

    PubMed

    Ackerman, Joshua T; Hartman, C Alex; Eagles-Smith, Collin A; Herzog, Mark P; Davis, Jay; Ichikawa, Gary; Bonnema, Autumn

    2015-11-17

    Methylmercury is a global pollutant of aquatic ecosystems, and monitoring programs need tools to predict mercury exposure of wildlife. We developed equations to estimate methylmercury exposure of piscivorous birds and sport fish using mercury concentrations in prey fish. We collected original data on western grebes (Aechmophorus occidentalis) and Clark's grebes (Aechmophorus clarkii) and summarized the published literature to generate predictive equations specific to grebes and a general equation for piscivorous birds. We measured mercury concentrations in 354 grebes (blood averaged 1.06 ± 0.08 μg/g ww), 101 grebe eggs, 230 sport fish (predominantly largemouth bass and rainbow trout), and 505 prey fish (14 species) at 25 lakes throughout California. Mercury concentrations in grebe blood, grebe eggs, and sport fish were strongly related to mercury concentrations in prey fish among lakes. Each 1.0 μg/g dw (∼0.24 μg/g ww) increase in prey fish resulted in an increase in mercury concentrations of 103% in grebe blood, 92% in grebe eggs, and 116% in sport fish. We also found strong correlations between mercury concentrations in grebes and sport fish among lakes. Our results indicate that prey fish monitoring can be used to estimate mercury exposure of piscivorous birds and sport fish when wildlife cannot be directly sampled.

  12. Profiles of polychlorinated biphenyl congeners, organochlorine pesticides, and butyltins in southern sea otters and their prey.

    PubMed

    Kannan, Kurunthachalam; Kajiwara, Natsuko; Watanabe, Mafumi; Nakata, Haruhiko; Thomas, Nancy J; Stephenson, Mark; Jessup, David A; Tanabe, Shinsuke

    2004-01-01

    Concentrations of organochlorine pesticides, polychlorinated biphenyl (PCB) congeners, and butyltins were measured in sea otters and selected prey species (invertebrates) collected from the California (USA) coast. Polychlorinated biphenyls, DDTs (sum of p,p'-dichlorodiphenyldichloroethylene [p,p'-DDE], p,p'-dichlorodiphenyldichloroethane [p,p'-DDD], and p,p'-DDT), and butyltins were the major contaminants found in sea otters and their prey. Lipid-normalized concentrations of PCBs and DDT in sea otter livers were 60- and 240-fold greater than those found in the prey. Great biomagnification of PCBs and DDT in sea otters is suggested to result from their high per-capita intake of diet compared with those of other marine mammals. Profiles of PCB congeners in sea otters and prey species suggest a great capacity of sea otters to biotransform lower-chlorinated congeners. Sea otters seem to possess a greater ability than cetaceans to metabolize PCBs. The 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents of non- and mono-ortho PCBs in sea otters and certain prey species were at or above the theoretical threshold for toxic effects.

  13. Profiles of polychlorinated biphenyl congeners, organochlorine pesticides and butlyns in southern sea otters and their prey

    USGS Publications Warehouse

    Kannan, K.; Kajiwara, N.; Watanabe, M. E.; Nakata, H.; Thomas, N.J.; Stephenson, M.; Jessup, David A.; Tanabe, S.

    2004-01-01

    Concentrations of organochlorine pesticides, polychlorinated biphenyl (PCB) congeners, and butyltins were measured in sea otters and selected prey species (invertebrates) collected from the California (USA) coast. Polychlorinated biphenyls, DDTs (sum of p,pa??-dichlorodiphenyldichloroethylene [p,pa??-DDE], p,pa??-dichlorodiphenyldichloroethane [p,pa??-DDD], and p,pa??-DDT), and butyltins were the major contaminants found in sea otters and their prey. Lipid-normalized concentrations of PCBs and DDT in sea otter livers were 60- and 240-fold greater than those found in the prey. Great biomagnification of PCBs and DDT in sea otters is suggested to result from their high per-capita intake of diet compared with those of other marine mammals. Profiles of PCB congeners in sea otters and prey species suggest a great capacity of sea otters to biotransform lower-chlorinated congeners. Sea otters seem to possess a greater ability than cetaceans to metabolize PCBs. The 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents of non- and mono-ortho PCBs in sea otters and certain prey species were at or above the theoretical threshold for toxic effects.

  14. Morphology does not predict performance: jaw curvature and prey crushing in durophagous stingrays.

    PubMed

    Kolmann, Matthew A; Crofts, Stephanie B; Dean, Mason N; Summers, Adam P; Lovejoy, Nathan R

    2015-12-01

    All stingrays in the family Myliobatidae are durophagous, consuming bivalves and gastropods, as well as decapod crustaceans. Durophagous rays have rigid jaws, flat teeth that interlock to form pavement-like tooth plates, and large muscles that generate bite forces capable of fracturing stiff biological composites (e.g. mollusk shell). The relative proportion of different prey types in the diet of durophagous rays varies between genera, with some stingray species specializing on particular mollusk taxa, while others are generalists. The tooth plate module provides a curved occlusal surface on which prey is crushed, and this curvature differs significantly among myliobatids. We measured the effect of jaw curvature on prey-crushing success in durophagous stingrays. We milled aluminum replica jaws rendered from computed tomography scans, and crushed live mollusks, three-dimensionally printed gastropod shells, and ceramic tubes with these fabricated jaws. Our analysis of prey items indicate that gastropods were consistently more difficult to crush than bivalves (i.e. were stiffer), but that mussels require the greatest work-to-fracture. We found that replica shells can provide an important proxy for investigations of failure mechanics. We also found little difference in crushing performance between jaw shapes, suggesting that disparate jaws are equally suited for processing different types of shelled prey. Thus, durophagous stingrays exhibit a many-to-one mapping of jaw morphology to mollusk crushing performance. PMID:26567348

  15. Coevolution of venom function and venom resistance in a rattlesnake predator and its squirrel prey.

    PubMed

    Holding, Matthew L; Biardi, James E; Gibbs, H Lisle

    2016-04-27

    Measuring local adaptation can provide insights into how coevolution occurs between predators and prey. Specifically, theory predicts that local adaptation in functionally matched traits of predators and prey will not be detected when coevolution is governed by escalating arms races, whereas it will be present when coevolution occurs through an alternate mechanism of phenotype matching. Here, we analyse local adaptation in venom activity and prey resistance across 12 populations of Northern Pacific rattlesnakes and California ground squirrels, an interaction that has often been described as an arms race. Assays of venom function and squirrel resistance show substantial geographical variation (influenced by site elevation) in both venom metalloproteinase activity and resistance factor effectiveness. We demonstrate local adaptation in the effectiveness of rattlesnake venom to overcoming present squirrel resistance, suggesting that phenotype matching plays a role in the coevolution of these molecular traits. Further, the predator was the locally adapted antagonist in this interaction, arguing that rattlesnakes are evolutionarily ahead of their squirrel prey. Phenotype matching needs to be considered as an important mechanism influencing coevolution between venomous animals and resistant prey.

  16. Estimating mercury exposure of piscivorous birds and sport fish using prey fish monitoring

    USGS Publications Warehouse

    Ackerman, Joshua T.; Hartman, C. Alex; Eagles-Smith, Collin A.; Herzog, Mark P.; Davis, Jay; Ichikawa, Gary; Bonnema, Autumn

    2015-01-01

    Methylmercury is a global pollutant of aquatic ecosystems, and monitoring programs need tools to predict mercury exposure of wildlife. We developed equations to estimate methylmercury exposure of piscivorous birds and sport fish using mercury concentrations in prey fish. We collected original data on western grebes (Aechmophorus occidentalis) and Clark’s grebes (Aechmophorus clarkii) and summarized the published literature to generate predictive equations specific to grebes and a general equation for piscivorous birds. We measured mercury concentrations in 354 grebes (blood averaged 1.06 ± 0.08 μg/g ww), 101 grebe eggs, 230 sport fish (predominantly largemouth bass and rainbow trout), and 505 prey fish (14 species) at 25 lakes throughout California. Mercury concentrations in grebe blood, grebe eggs, and sport fish were strongly related to mercury concentrations in prey fish among lakes. Each 1.0 μg/g dw (∼0.24 μg/g ww) increase in prey fish resulted in an increase in mercury concentrations of 103% in grebe blood, 92% in grebe eggs, and 116% in sport fish. We also found strong correlations between mercury concentrations in grebes and sport fish among lakes. Our results indicate that prey fish monitoring can be used to estimate mercury exposure of piscivorous birds and sport fish when wildlife cannot be directly sampled.

  17. Modelled three-dimensional suction accuracy predicts prey capture success in three species of centrarchid fishes

    PubMed Central

    Kane, Emily A.; Higham, Timothy E.

    2014-01-01

    Prey capture is critical for survival, and differences in correctly positioning and timing a strike (accuracy) are likely related to variation in capture success. However, an ability to quantify accuracy under natural conditions, particularly for fishes, is lacking. We developed a predictive model of suction hydrodynamics and applied it to natural behaviours using three-dimensional kinematics of three centrarchid fishes capturing evasive and non-evasive prey. A spheroid ingested volume of water (IVW) with dimensions predicted by peak gape and ram speed was verified with known hydrodynamics for two species. Differences in capture success occurred primarily with evasive prey (64–96% success). Micropterus salmoides had the greatest ram and gape when capturing evasive prey, resulting in the largest and most elongate IVW. Accuracy predicted capture success, although other factors may also be important. The lower accuracy previously observed in M. salmoides was not replicated, but this is likely due to more natural conditions in our study. Additionally, we discuss the role of modulation and integrated behaviours in shaping the IVW and determining accuracy. With our model, accuracy is a more accessible performance measure for suction-feeding fishes, which can be used to explore macroevolutionary patterns of prey capture evolution. PMID:24718455

  18. Status of Pelagic Prey Fishes in Lake Michigan, 2014

    USGS Publications Warehouse

    Warner, David M.; Farha, Steven A.; Claramunt, Randall M.; Hanson, Dale; O'Brien, Timothy P.

    2015-01-01

    Acoustic surveys were conducted in late summer/early fall during the years 1992-1996 and 2001-2014 to estimate pelagic prey fish biomass in Lake Michigan. Midwater trawling during the surveys as well as target strength provided a measure of species and size composition of the fish community for use in scaling acoustic data and providing species-specific abundance estimates. The 2014 survey consisted of 27 acoustic transects (603 km total) and 31 midwater trawl tows. Four additional transects were sampled in Green Bay but were not included in lakewide estimates. Mean prey fish biomass was 6.5 kg/ha [31.7 kilotonnes (kt = 1,000 metric tons)], equivalent to 69.9 million pounds, which was similar to the estimate in 2013 (29.6 kt) and 25% of the long-term (19 years) mean. The numeric density of the 2014 alewife year-class was 3% of the time series average and was the lowest observed in the 19 years of sampling. This year-class contributed <1% of total alewife biomass (4.6 kg/ha). Alewife ≥age-1 comprised 99.5% of alewife biomass. Numeric density of alewife in Green Bay was more than three times that of the main lake. In 2014, alewife comprised 71% of total prey fish biomass, while rainbow smelt and bloater were 1% and 28% of total biomass, respectively. Rainbow smelt biomass in 2014 (0.08 kg/ha) was 66% lower than in 2013, 2% of the long-term mean, and lower than in any previous year. Bloater biomass in 2014 was 1.8 kg/ha, nearly three times more than the 2013 biomass, and 20% of the long-term mean. Mean density of small bloater in 2014 (122 fish/ha) was lower than peak values observed in 2007-2009 but was similar to the time series mean (124 fish/ha). In 2014, pelagic prey fish biomass in Lake Michigan was 71% of that in Lake Huron (all basins), where the community is dominated by bloater.

  19. Net trophic transfer efficiency of PCBs to Lake Michigan coho salmon from their prey

    USGS Publications Warehouse

    Madenjian, Charles P.; Elliott, Robert F.; Schmidt, Larry J.; DeSorcie, Timothy J.; Hesselberg, Robert J.; Quintal, Richard T.; Begnoche, Linda J.; Bouchard, Patrick M.; Holey, Mark E.

    1998-01-01

    Most of the polychlorinated biphenyl (PCB) body burden accumulated by coho salmon (Oncorhynchus kisutch) from the Laurentian Great Lakes is from their food. We used diet information, PCB determinations in both coho salmon and their prey, and bioenergetics modeling to estimate the efficiency with which Lake Michigan coho salmon retain PCBs from their food. Our estimate was the most reliable estimate to date because (a) the coho salmon and prey fish sampled during our study were sampled in spring, summer, and fall from various locations throughout the lake, (b) detailed measurements were made on the PCB concentrations of both coho salmon and prey fish over wide ranges in fish size, and (c) coho salmon diet was analyzed in detail from April through November over a wide range of salmon size from numerous locations throughout the lake. We estimated that coho salmon from Lake Michigan retain 50% of the PCBs that are contained within their food.

  20. Net trophic transfer efficiency of PCBs to Lake Michigan coho salmon from their prey

    SciTech Connect

    Madenjian, C.P.; Schmidt, L.J.; Desorcie, T.J.; Hesselberg, R.J.; Quintal, R.T.; Begnoche, L.J.; Elliott, R.F.; Bouchard, P.M.; Holey, M.E.

    1998-10-15

    Most of the polychlorinated biphenyl (PCB) body burden accumulated by coho salmon (Oncorhynchus kisutch) from the Laurentian Great Lakes is from their food. The authors used diet information, PCB determinations in both coho salmon and their prey, and bioenergetics modeling to estimate the efficiency with which Lake Michigan coho salmon retain PCBs from their food. The estimate was the most reliable estimate to date because (a) the coho salmon and prey fish sampled during the study were sampled in spring, summer, and fall from various locations throughout the lake, (b) detailed measurements were made on the PCB concentrations of both coho salmon and prey fish over wide ranges in fish size, and (c) coho salmon diet was analyzed in detail from April through November over a wide range of salmon size from numerous locations throughout the lake. The authors estimated that coho salmon from Lake Michigan retain 50%$ of the PCBs that are contained within their food.

  1. Mechanical performance of spider orb webs is tuned for high-speed prey.

    PubMed

    Sensenig, Andrew T; Kelly, Sean P; Lorentz, Kimberly A; Lesher, Brittany; Blackledge, Todd A

    2013-09-15

    Spiders in the Orbiculariae spin orb webs that dissipate the mechanical energy of their flying prey, bringing the insects to rest and retaining them long enough for the spider to attack and subdue their meals. Small prey are easily stopped by webs but provide little energetic gain. While larger prey offer substantial nourishment, they are also challenging to capture and can damage the web if they escape. We therefore hypothesized that spider orb webs exhibit properties that improve their probability of stopping larger insects while minimizing damage when the mechanical energy of those prey exceeds the web's capacity. Large insects are typically both heavier and faster flying than smaller prey, but speed plays a disproportionate role in determining total kinetic energy, so we predicted that orb webs may dissipate energy more effectively under faster impacts, independent of kinetic energy per se. We used high-speed video to visualize the impact of wooden pellets fired into orb webs to simulate prey strikes and tested how capture probability varied as a function of pellet size and speed. Capture probability was virtually nil above speeds of ~3 m s(-1). However, successful captures do not directly measure the maximum possible energy dissipation by orb webs because these events include lower-energy impacts that may not significantly challenge orb web performance. Therefore, we also compared the total kinetic energy removed from projectiles that escaped orb webs by breaking through the silk, asking whether more energy was removed at faster speeds. Over a range of speeds relevant to insect flight, the amount of energy absorbed by orb webs increases with the speed of prey (i.e. the rates at which webs are stretched). Orb webs therefore respond to faster - and hence higher kinetic energy - prey with better performance, suggesting adaptation to capture larger and faster flying insect prey. This speed-dependent toughness of a complex structure suggests the utility of the

  2. Mechanical performance of spider orb webs is tuned for high-speed prey.

    PubMed

    Sensenig, Andrew T; Kelly, Sean P; Lorentz, Kimberly A; Lesher, Brittany; Blackledge, Todd A

    2013-09-15

    Spiders in the Orbiculariae spin orb webs that dissipate the mechanical energy of their flying prey, bringing the insects to rest and retaining them long enough for the spider to attack and subdue their meals. Small prey are easily stopped by webs but provide little energetic gain. While larger prey offer substantial nourishment, they are also challenging to capture and can damage the web if they escape. We therefore hypothesized that spider orb webs exhibit properties that improve their probability of stopping larger insects while minimizing damage when the mechanical energy of those prey exceeds the web's capacity. Large insects are typically both heavier and faster flying than smaller prey, but speed plays a disproportionate role in determining total kinetic energy, so we predicted that orb webs may dissipate energy more effectively under faster impacts, independent of kinetic energy per se. We used high-speed video to visualize the impact of wooden pellets fired into orb webs to simulate prey strikes and tested how capture probability varied as a function of pellet size and speed. Capture probability was virtually nil above speeds of ~3 m s(-1). However, successful captures do not directly measure the maximum possible energy dissipation by orb webs because these events include lower-energy impacts that may not significantly challenge orb web performance. Therefore, we also compared the total kinetic energy removed from projectiles that escaped orb webs by breaking through the silk, asking whether more energy was removed at faster speeds. Over a range of speeds relevant to insect flight, the amount of energy absorbed by orb webs increases with the speed of prey (i.e. the rates at which webs are stretched). Orb webs therefore respond to faster - and hence higher kinetic energy - prey with better performance, suggesting adaptation to capture larger and faster flying insect prey. This speed-dependent toughness of a complex structure suggests the utility of the

  3. Pyrazine odour makes visually conspicuous prey aversive.

    PubMed

    Lindström, L; Rowe, C; Guilford, T

    2001-01-22

    Unpalatable insects frequently adopt multimodal signals to ward off predators, incorporating sounds and odours into their colourful displays. Pyrazine is an odour commonly used in insect warning displays, and has previously been shown to elicit unlearned biases against common warning colours, e.g. yellow and red in naive predators. We designed two experiments to test for similar effects of pyrazine on the conspicuousness of prey, perhaps the most ubiquitous aspect of aposematic coloration. In the first experiment, we offered predators (Gallus gallus domesticus) a choice between conspicuous crumbs and cryptic crumbs in the presence or absence of pyrazine. In the second experiment, we manipulated the birds' experience of conspicuous prey during an initial training phase. Only in the presence of pyrazine did birds show a bias against conspicuously coloured food, and this occurred whether or not they had previously experienced food that contrasted with the background. This emergent behaviour relied upon the visual and odorous signal components being presented together. These unlearned, yet hidden, responses against conspicuousness demonstrate that there are initial benefits to prey being conspicuous when the multimodal nature of warning signals is accounted for.

  4. Pollinator-prey conflict in carnivorous plants.

    PubMed

    Jürgens, Andreas; Sciligo, Amber; Witt, Taina; El-Sayed, Ashraf M; Suckling, D Max

    2012-08-01

    Most carnivorous plants utilize insects in two ways: the flowers attract insects as pollen vectors for sexual reproduction, and the leaves trap insects for nutrients. Feeding on insects has been explained as an adaptation to nutrient-poor soil, and carnivorous plants have been shown to benefit from insect capture through increased growth, earlier flowering and increased seed production. Most carnivorous plant species seem to benefit from insect pollination, although many species autonomously self-pollinate and some propagate vegetatively. However, assuming that outcross pollen is advantageous and is a more important determinant of reproductive success than the nutrients gained from prey, there should be a selective pressure on carnivorous plants not to feed on their potential pollen vectors. Therefore, it has been suggested that carnivorous plants are subject to a conflict, often called the pollinator-prey conflict (PPC). The conflict results from a trade-off of the benefits from feeding on potentially pollinating insects versus the need to use them as pollen vectors for sexual reproduction. In this review we analyze the conditions under which a PPC may occur, review the evidence for the existence of PPCs in carnivorous plants, and explore the mechanisms that may be in place to prevent or alleviate a PPC. With respect to the latter, we discuss how plant signals such as olfactory and visual cues may play a role in separating the functions of pollinator attraction and prey capture.

  5. Infomechanical specializations for prey capture in knifefish

    NASA Astrophysics Data System (ADS)

    Maciver, Malcolm; Patankar, Neelesh; Curet, Oscar; Shirgaonkar, Anup

    2007-11-01

    How does an animal's mechanics and its information acquisition system work together to solve crucial behavioral tasks? We examine this question for the black ghost weakly electric knifefish (Apteronotus albifrons), which is a leading model system for the study of sensory processing in vertebrates. These animals hunt at night by detecting perturbations of a self-generated electric field caused by prey. While the fish searches for prey, it pitches at 30 . Fully resolved Navier-Stokes simulations of their swimming, which occurs through undulations of a long ribbon-like fin along the bottom edge of the body, indicates that this configuration enables maximal thrust while minimizing pitch moment. However, pitching the body also increases drag. Our analysis of the sensory volume for detection of prey shows this volume to be similar to a cylinder around the body. Thus, pitching the body enables a greater swept volume of scanned fluid. Examining the mechanical and information acquisition demands on the animal in this task gives insight into how these sometimes conflicting demands are resolved.

  6. Prototype sampling system for measuring workplace protection factors for gases and vapors.

    PubMed

    Groves, William A; Reynolds, Stephen J

    2003-05-01

    A prototype sampling system for measuring respirator workplace protection factors (WPFs) was developed. Methods for measuring the concentration of contaminants inside respirators have previously been described; however, these studies have typically involved continuous sampling of aerosols. Our work focuses on developing an intermittent sampling system designed to measure the concentration of gases and vapors during inspiration. This approach addresses two potential problems associated with continuous sampling: biased results due to lower contaminant concentrations and high humidity in exhaled air. The system consists of a pressure transducer circuit designed to activate a pair of personal sampling pumps during inspiration based on differential pressure inside the respirator. One pump draws air from inside the respirator while the second samples the ambient air. Solid granular adsorbent tubes are used to trap the contaminants, making the approach applicable to a large number of gases and vapors. Laboratory testing was performed using a respirator mounted on a headform connected to a breathing machine producing a sinusoidal flow pattern with an average flow rate of 20 L/min and a period of 3 seconds. The sampling system was adjusted to activate the pumps when the pressure inside the respirator was less than -0.1 inch H(2)O. Quantitative fit-tests using human subjects were conducted to evaluate the effect of the sampling system on respirator performance. A total of 299 fit-tests were completed for two different types of respirators (half- and full-facepiece) from two different manufacturers (MSA and North). Statistical tests showed no significant differences between mean fit factors for respirators equipped with the sampling system versus unmodified respirators. Field testing of the prototype sampling system was performed in livestock production facilities and estimates of WPFs for ammonia were obtained. Results demonstrate the feasibility of this approach and will be

  7. Effect of green tea as a protective measure against dental erosion in coronary dentine.

    PubMed

    De Moraes, Maria Denise Rodrigues; Carneiro, Jéssica Rodrigues Mendes; Passos, Vanara Florêncio; Santiago, Sérgio Lima

    2016-01-01

    The aim of this study was to evaluate the effect of green tea as a protective measure on eroded dentin. Disks of human coronary dentin were selected based on surface hardness and randomly assigned to 3 groups (n = 10): DW - distilled water, CHX - 0.2% chlorhexidine digluconate, and GT - green tea. The disks were allowed to acquire pellicle for 2 hours and were then subjected to 3 cycles per day of demineralization (C6H8O7 0.05 M, pH 3.75, 60 s), treatment (DW or CHX or GT, 5 min) and remineralization (artificial saliva, 60 min) over a period of 3 days. Changes in the dentin were determined by loss of surface hardness (%SHL) and mechanical profilometry analysis at the end of each day. Data were analyzed by two-way ANOVA followed by Tukey's test for %SHL and profilometry (p < 0.05). Significant reductions in dentin hardness loss were observed only for the CHX group when compared to the DW group (p < 0.05). However, there was no significant difference between the CHX and GT groups (p > 0.05). A significant difference was observed between DW and GT treatments for wear and roughness measurements (p < 0.05). The green tea extract solution was able to reduce the wear and roughness caused by dentin erosion under the conditions of this study.

  8. Effect of green tea as a protective measure against dental erosion in coronary dentine.

    PubMed

    De Moraes, Maria Denise Rodrigues; Carneiro, Jéssica Rodrigues Mendes; Passos, Vanara Florêncio; Santiago, Sérgio Lima

    2016-01-01

    The aim of this study was to evaluate the effect of green tea as a protective measure on eroded dentin. Disks of human coronary dentin were selected based on surface hardness and randomly assigned to 3 groups (n = 10): DW - distilled water, CHX - 0.2% chlorhexidine digluconate, and GT - green tea. The disks were allowed to acquire pellicle for 2 hours and were then subjected to 3 cycles per day of demineralization (C6H8O7 0.05 M, pH 3.75, 60 s), treatment (DW or CHX or GT, 5 min) and remineralization (artificial saliva, 60 min) over a period of 3 days. Changes in the dentin were determined by loss of surface hardness (%SHL) and mechanical profilometry analysis at the end of each day. Data were analyzed by two-way ANOVA followed by Tukey's test for %SHL and profilometry (p < 0.05). Significant reductions in dentin hardness loss were observed only for the CHX group when compared to the DW group (p < 0.05). However, there was no significant difference between the CHX and GT groups (p > 0.05). A significant difference was observed between DW and GT treatments for wear and roughness measurements (p < 0.05). The green tea extract solution was able to reduce the wear and roughness caused by dentin erosion under the conditions of this study. PMID:26676195

  9. 75 FR 77535 - Fisheries of the Exclusive Economic Zone Off Alaska; Steller Sea Lion Protection Measures for the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-13

    ... measures. These protection measures were implemented in 2002 by emergency interim rule (67 FR 956, January 8, 2002; amended 67 FR 21600, May 1, 2002; corrected 67 FR 45671, July 10, 2002, 67 FR 47472, July 19, 2002, and 67 FR 64315, October 18, 2002; and extended 67 FR 34860, May 16, 2002) and by...

  10. Psychometric Properties of Three Measures of Protective Factors for Depression and Suicidal Behaviour Among Adolescents

    PubMed Central

    Labelle, Réal; Breton, Jean-Jacques; Berthiaume, Claude; Royer, Chantal; Raymond, Sylvie; Cournoyer, Marilou; Balan, Bogdan; Zaloum, Terry; Bibaud, Antoine; Gauvin, Geoffrey; Janelle, Alain

    2015-01-01

    Objectives: To assess the reliability of French versions of the Adolescent Coping Scale (ACS), the Reasons for Living Inventory for Adolescents (RFL-A), and the Spirituality Scale (SS); to examine the construct validity of these psychometric instruments; and to determine their convergent validity with French versions of the Life Events Questionnaire for Adolescents (LEQ-A), the Beck Depression Inventory-Second Edition (BDI-II), and the Beck Hopelessness Scale (BHS) among French-Canadian adolescents. Methods: Participants were 429 adolescents from high schools (n = 283) and the Mood Disorder Clinic (n = 146) in Montreal. The instruments were translated into French following the back-translation method. The internal consistency was assessed through Cronbach alpha coefficients. Exploratory analyses were conducted to document the content of their dimensions. Convergent validity was examined by correlating the ACS, the RFL-A, and the SS with the French versions of the LEQ-A, the BDI-II, and the BHS. Results: The findings confirm that the ACS, RFL-A, and SS are psychometric instruments well suited to assess protective factors for depression and suicidal behaviour among French-speaking adolescents in community and clinical settings. However, results must be interpreted with some circumspection as 2 SS subscales obtained reliability coefficients in the moderate range only and the instructions for the RFL-A were reframed in response to ethical considerations. Conclusions: Our results add to those already available on the original English versions of the ACS, RFL-A, and SS and advance the knowledge of the psychometric properties of protective measures. PMID:25886667

  11. Rates of reinforcement and measures of compliance in free and protected contact elephant management systems.

    PubMed

    Wilson, Megan L; Perdue, Bonnie M; Bloomsmith, Mollie A; Maple, Terry L

    2015-01-01

    Protected contact is an alternative to traditional captive elephant training techniques that emerged as a result of concerns for animal welfare and personnel safety. The present study documented the behavior of elephants and their animal care professionals to determine rates of reinforcement and measures of compliance under two handling systems. Behavioral data were collected from animal care professionals and elephants during the elephants' baths in both free contact (FC) and protected contact (PC). Positive reinforcement, in the form of food, was delivered, on average, nearly eight times more frequently in the PC condition. Further, the mean rate at which the animal care professionals used the ankus in the FC condition as negative reinforcement was similar to the mean rate at which they provided positive reinforcement to the elephants in the FC condition. Latencies between verbal commands and the elephants' behaviors demonstrated an inconsistent pattern, but were generally longer in the PC condition. The mean percent of "refusals" by the elephants was higher for most behaviors across elephants in the PC condition. The findings suggest that animal care professionals did not heavily rely on positive reinforcement in the FC condition to elicit desired behaviors from the elephants, but this was the case in the PC condition. We propose that longer latencies and higher mean percent of refusals by the elephants may indicate that they were exercising choice or control over their environment, which has been associated with improved well-being. Additional studies of this kind are needed to enable other institutions to make informed decisions about elephant management and welfare.

  12. Rates of reinforcement and measures of compliance in free and protected contact elephant management systems.

    PubMed

    Wilson, Megan L; Perdue, Bonnie M; Bloomsmith, Mollie A; Maple, Terry L

    2015-01-01

    Protected contact is an alternative to traditional captive elephant training techniques that emerged as a result of concerns for animal welfare and personnel safety. The present study documented the behavior of elephants and their animal care professionals to determine rates of reinforcement and measures of compliance under two handling systems. Behavioral data were collected from animal care professionals and elephants during the elephants' baths in both free contact (FC) and protected contact (PC). Positive reinforcement, in the form of food, was delivered, on average, nearly eight times more frequently in the PC condition. Further, the mean rate at which the animal care professionals used the ankus in the FC condition as negative reinforcement was similar to the mean rate at which they provided positive reinforcement to the elephants in the FC condition. Latencies between verbal commands and the elephants' behaviors demonstrated an inconsistent pattern, but were generally longer in the PC condition. The mean percent of "refusals" by the elephants was higher for most behaviors across elephants in the PC condition. The findings suggest that animal care professionals did not heavily rely on positive reinforcement in the FC condition to elicit desired behaviors from the elephants, but this was the case in the PC condition. We propose that longer latencies and higher mean percent of refusals by the elephants may indicate that they were exercising choice or control over their environment, which has been associated with improved well-being. Additional studies of this kind are needed to enable other institutions to make informed decisions about elephant management and welfare. PMID:26179311

  13. Measuring the difference made by conservation initiatives: protected areas and their environmental and social impacts

    PubMed Central

    Ferraro, Paul J.; Pressey, Robert L.

    2015-01-01

    Success in conservation depends on our ability to reduce human pressures in areas that harbour biological diversity and ecosystem services. Legally protecting some of these areas through the creation of protected areas is a key component of conservation efforts globally. To develop effective protected area networks, practitioners need credible, scientific evidence about the degree to which protected areas affect environmental and social outcomes, and how these effects vary with context. Such evidence has been lacking, but the situation is changing as conservation scientists adopt more sophisticated research designs for evaluating protected areas' past impacts and for predicting their future impacts. Complementing these scientific advances, conservation funders and practitioners are paying increasing attention to evaluating their investments with more scientifically rigorous evaluation designs. This theme issue highlights recent advances in the science of protected area evaluations and explores the challenges to developing a more credible evidence base that can help societies achieve their goals of protecting nature while enhancing human welfare. PMID:26460123

  14. Attitudes, Beliefs, and Measures Taken by Parents to Protect Their Children from the Sun in Guangzhou City, China.

    PubMed

    Wan, Miaojian; Hu, Rong; Li, Ying; Wang, Yaning; Xie, Xiaoyuan; Yue, Pan; Guan, Lei; Lai, Wei

    2016-09-01

    Excessive sun exposure can cause sunburn, suntan, skin photoaging, and even skin cancer. Skin photoaging conflicts with the human pursuit of a young and beautiful appearance. Some research data indicate that the incidence of skin cancer in the Chinese has been increasing, although it remains lower than in whites. To estimate the prevalence of sun protection used on Chinese children aged 3-13 years and identify its predictors, a population-based cross-sectional questionnaire was given to 3684 parents/guardians of children in Guangzhou, China, of which 3083 questionnaires were returned. Of those returned, 35.5% of parents/guardians reported regularly using sun protection on their children and the primary reason cited was to prevent sunburn. Hats and handheld umbrellas were the most frequently used measures; sunscreen was less common, and when used, 48.8% of parents/guardians still reapplied sunscreen on their children every 2.0-3.0 h. Parental age, parents using sun protection measures themselves when outdoors, and the child's sex were factors associated with regular use of sun protection on children. These results suggest that sun protection campaigns targeted toward parents and children need to be conducted in Guangzhou, or throughout China, to strengthen awareness about sun protection and address any inadequate protocols of sun protection. PMID:27463620

  15. SOHO hunts elusive solar prey

    NASA Astrophysics Data System (ADS)

    1995-10-01

    out into the solar atmosphere where they mould the electrified gas into an ever-changing shape. The entire atmosphere is continuously transformed by the Sun's varying magnetism, producing activity on a scale unknown on Earth. Looking inside the Sun There are three helioseismology experts on board SOHO that will acquire long uninterrupted observations of solar oscillations. Two of them emphasise global, long-period oscillations and sound waves that can penetrate the deep solar interior. They are known as GOLF, for Global Oscillations at Low Frequency, and VIRGO, an acronym for Variability of solar IRradiance and Gravity Oscillations. The third SOHO helioseismology instrument will obtain data for oscillations on smaller spatial scales with unprecedented precision; it is called the Solar Oscillations Investigation/Michelson Doppler Imager, or SOI/MDI for short. GOLF and MDI employ the familiar Doppler technique for measuring motions of the solar photosphere. When part of the visible surface heaves up towards us, the wavelength of a spectral line formed in that region is shortened; if the region moves away from us, back toward the solar interior, the wavelength is lengthened. (A spectral line absorbed or emitted by an atom or an ion at a specific wavelength that identifies the element; it looks like a line in a spectral display of radiation intensity as a function of wavelength). Sound waves can also be used to determine the internal rotation of the Sun. Waves propagating in the direction of rotation will appear, to a fixed observer, to move faster and their measure speeds will be shorter. Waves propagating against the rotation will be slowed down with longer periods. Accurate measurements of this oscillation period splitting will determine rotation within the solar interior. GOLF aims to measure velocities as low as 1 millimetre per second for global surface oscillations with periods from 3 minutes to 100 days. SOI/MDI will obtain precise oscillation data with high

  16. Diet of Chinese skink, Eumeces chinensis: is prey size important?

    PubMed

    Chen, Xiaolin; Jiang, Yong

    2006-06-01

    The diet of the skink, Eumeces chinensis (Lacertilia: Scincidae), in Xiamen (Amoy), China was examined using stomach analysis during April and May, and its selection of prey size was tested by feeding trials. Insects (primarily Coleoptera, Lepidoptera, and Orthoptera), gastropods and arachnids constituted most of the E. chinensis diet, but earthworms, leeches, crustaceans and fish were also consumed. In the field, male skinks ate more prey items that were 11-20 mm in length than other size classes. When presented with a choice of different-sized prey in the laboratory, male E. chinensis exhibited a strong preference for prey items 11-20 mm in length over other size classes. The relationship between prey size and handling time was exponential, indicating that there is an upper limit to the ability of E. chinensis to process prey. Mean energy intake for handling different-sized prey showed that selection of midsizeclass prey items would provide male E. chinensis with the most energy-efficient prey option. These results indicate that prey size selection in E. chinensis favors maximization of rates of energy intake, which is in agreement with optimal foraging theory. PMID:21395993

  17. Prey selection by the Lake Superior fish community

    USGS Publications Warehouse

    Isaac, Edmund J.; Hrabik, Thomas R.; Stockwell, Jason D.; Gamble, Allison E.

    2012-01-01

    Mysis diluviana is an important prey item to the Lake Superior fish community as found through a recent diet study. We further evaluated this by relating the quantity of prey found in fish diets to the quantity of prey available to fish, providing insight into feeding behavior and prey preferences. We describe the seasonal prey selection of major fish species collected across 18 stations in Lake Superior in spring, summer, and fall of 2005. Of the major nearshore fish species, bloater (Coregonus hoyi), rainbow smelt (Osmerus mordax), and lake whitefish (Coregonus clupeaformis) consumed Mysis, and strongly selected Mysis over other prey items each season. However, lake whitefish also selected Bythotrephes in the fall when Bythotrephes were numerous. Cisco (Coregonus artedi), a major nearshore and offshore species, fed largely on calanoid copepods, and selected calanoid copepods (spring) and Bythotrephes (summer and fall). Cisco also targeted prey similarly across bathymetric depths. Other major offshore fish species such as kiyi (Coregonus kiyi) and deepwater sculpin (Myoxocephalus thompsoni) fed largely on Mysis, with kiyi targeting Mysis exclusively while deepwater sculpin did not prefer any single prey organism. The major offshore predator siscowet lake trout (Salvelinus namaycush siscowet) consumed deepwater sculpin and coregonines, but selected deepwater sculpin and Mysis each season, with juveniles having a higher selection for Mysis than adults. Our results suggest that Mysis is not only a commonly consumed prey item, but a highly preferred prey item for pelagic, benthic, and piscivorous fishes in nearshore and offshore waters of Lake Superior.

  18. Increased predation of nutrient-enriched aposematic prey

    PubMed Central

    Halpin, Christina G.; Skelhorn, John; Rowe, Candy

    2014-01-01

    Avian predators readily learn to associate the warning coloration of aposematic prey with the toxic effects of ingesting them, but they do not necessarily exclude aposematic prey from their diets. By eating aposematic prey ‘educated’ predators are thought to be trading-off the benefits of gaining nutrients with the costs of eating toxins. However, while we know that the toxin content of aposematic prey affects the foraging decisions made by avian predators, the extent to which the nutritional content of toxic prey affects predators' decisions to eat them remains to be tested. Here, we show that European starlings (Sturnus vulgaris) increase their intake of a toxic prey type when the nutritional content is artificially increased, and decrease their intake when nutritional enrichment is ceased. This clearly demonstrates that birds can detect the nutritional content of toxic prey by post-ingestive feedback, and use this information in their foraging decisions, raising new perspectives on the evolution of prey defences. Nutritional differences between individuals could result in equally toxic prey being unequally predated, and might explain why some species undergo ontogenetic shifts in defence strategies. Furthermore, the nutritional value of prey will likely have a significant impact on the evolutionary dynamics of mimicry systems. PMID:24598424

  19. [Contraception and protection against STDs. CERPOD measures use of the Protector condom in Mali].

    PubMed

    Konate, M K

    1993-08-01

    In April 1993, a technical assistance contract to measure general condom use, particularly use of the brand name Protector, which has been marketed in Mali since March 1992, was made between the Center of Studies and Research on Population for Development (CERPOD) and the Popular Pharmacy of Mali. In June-July 1991, the SOMARC project and the Malian Institute for Applied Research in Development conducted a baseline survey to determine the condom use rate in Mali before Protector was introduced on the Malian market, so the social marketing project for contraception could be evaluated. It examined knowledge, use, and achievable target level and determined the characteristics of users of the Protector condom. It revealed that more than 90% of both men and women believed birth spacing was a good idea. Men approved of birth spacing for cost-saving reasons, while women approved birth spacing because it allowed mothers time to recuperate between births. Another earlier study in 1987 in Bamako found that 78% of the women already favored birth spacing. 90% of the men in the main cities in Mali knew about condoms. 63% of these men had used them in the past, mainly to prevent sexually transmitted diseases. 30% used them consistently. One hoped that this number was going to grow, since 80% of the men said that they would use condoms in the future. The evaluation of the 1991 social marketing campaign will end in August 1993 and will measure whether it was successful or not. In November 1992, CERPOD followed the framework of a recent baseline survey for an IEC (information, education, and communication) family planning program, operated jointly by the Malian Association for the Protection and Promotion of the Family and Population Communication Services, to measure the effect of the brand name Protector. CERPOD's survey results will be compared with those of the 1993 survey.

  20. Clearance rates of ephyrae and small medusae of the common jellyfish Aurelia aurita offered different types of prey

    NASA Astrophysics Data System (ADS)

    Riisgård, Hans Ulrik; Madsen, Caroline V.

    2011-01-01

    Prey selection and knowledge of the amounts of water processed by the early stages of the common jellyfish Aurelia aurita may at certain times of the year be crucial for understanding the plankton dynamics in marine ecosystems with mass occurrences of this jellyfish. In the present study we used two different methods ("clearance method" and "ingestion-rate method") to estimate the amount of water cleared per unit of time of different types and sizes of prey organisms offered to A. aurita ephyrae and small medusae. The mean clearance rates of medusae, estimated with Artemia sp. nauplii as prey by both methods, agreed well, namely 3.8 ± 1.4 l h - 1 by the clearance method and 3.2 ± 1.1 l h - 1 by the ingestion-rate method. Both methods showed that copepods (nauplii and adults) and mussel veligers are captured with considerably lower efficiency, 22 to 37% and 14 to 30%, respectively, than Artemia salina nauplii. By contrast, the water processing rates of ephyrae measured by the clearance method with A. salina nauplii as prey were 3 to 5 times lower than those measured by the ingestion-rate method. This indicates that the prerequisite of full mixing for using the clearance method may not have been fulfilled in the ephyrae experiments. The study demonstrates that the predation impact of the young stages of A. aurita is strongly dependent on its developmental stage (ephyra versus medusa), and the types and sizes of prey organisms. The estimated prey-digestion time of 1.3 h in a steady-state feeding experiment with constant prey concentration supports the reliability of the ingestion-rate method, which eliminates the negative "container effects" of the clearance method, and it seems to be useful in future jellyfish studies, especially on small species/younger stages in which both type and number of prey can be easily and precisely assessed.

  1. Predator-Prey Model for Haloes in Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Esposito, Larry W.; Colwell, Joshua; Sremcevic, Miodrag; Madhusudhanan, Prasanna

    Particles in Saturn’s rings have a tripartite nature: (1) a broad distribution of fragments from the disruption of a previous moon that accrete into (2) transient aggregates, resembling piles of rubble, covered by a (3) regolith of smaller grains that result from collisions and meteoritic grinding. Evidence for this triple architecture of ring particles comes from a multitude of Cassini observations. In a number of ring locations (including Saturn’s F ring, the shepherded outer edges of rings A and B and at the locations of the strongest density waves) aggregation and dis-aggregation are operating now. ISS, VIMS, UVIS spectroscopy and occultations show haloes around the strongest density waves. Based on a predator-prey model for ring dynamics, we offer the following explanation: •Cyclic velocity changes cause the perturbed regions to reach higher collision speeds at some orbital phases, which preferentially removes small regolith particles; •This forms a bright halo around the ILR, if the forcing is strong enough; •Surrounding particles diffuse back too slowly to erase the effect; they diffuse away to form the halo. The most rapid time scale is for forcing/aggregate growth/disaggregation; then irreversible regolith erosion; diffusion and/or ballistic transport; and slowest, meteoritic pollution/darkening. We observe both smaller and larger particles at perturbed regions. Straw, UVIS power spectral analysis, kittens and equinox objects show the prey (mass aggregates); while the haloes’ VIMS spectral signature, correlation length and excess variance are created by the predators (velocity dispersion) in regions stirred in the rings. Moon forcing triggers aggregation to create longer-lived aggregates that protect their interiors from meteoritic darkening and recycle the ring material to maintain the current purity of the rings. It also provides a mechanism for creation of new moons at resonance locations in the Roche zone, as proposed by Charnoz etal and

  2. Patterns of prey capture and prey availability among populations of the carnivorous plant Pinguicula moranensis (Lentibulariaceae) along an environmental gradient.

    PubMed

    Alcalá, Raúl E; Domínguez, César A

    2003-09-01

    In this study we explored the effect of the physical environment and the availability of prey (biomass and taxonomic composition) on the patterns of prey capture and reproduction on five populations of Pinguicula moranensis (Lentibulariaceae) in areas ranging from pine-oak forests to desert scrublands. Environmental variation was summarized using principal factor analysis. Prey availability and prey capture increased toward the shadiest, most humid, and fertile population. The probability of reproduction and average bud production per population did not follow the same tendency because both fitness components peaked at the middle of the environmental gradient. These results suggest that the benefits derived from carnivory are maximized at sites fulfilling a trade-off between light, moisture, and prey availability. We also found that the taxonomic composition of both the available prey and that of the prey captured by plants varied among populations. The results also indicated that the prey captured by plants are not a random sample of prey available within populations. Overall, the results from this study revealed a marked amount of heterogeneity in the physical and biotic environment among the populations of P. moranensis, which has the potential to affect the outcome of the interaction between this carnivorous species and its prey.

  3. Demographic differences in diet breadth of Canada lynx during a fluctuation in prey availability.

    PubMed

    Burstahler, Christa M; Roth, James D; Gau, Robert J; Murray, Dennis L

    2016-09-01

    Population dynamics of specialist carnivores are closely linked to prey availability, but the extent of variability in diet breadth of individual carnivores relative to natural variability in the abundance of their primary prey is not well understood. Canada lynx (Lynx canadensis) specialize on snowshoe hares (Lepus americanus) and exhibit cyclic fluctuations in abundance that lag 1-2 years behind those of snowshoe hares. Declining hare densities spur demographic changes in lynx, but it is unclear whether a corresponding increase in diet breadth occurs: (1) broadly across a lynx population; (2) only among individuals who are able to effectively switch to alternative prey; or (3) only among individuals who cannot capture sufficient primary prey. We measured stable isotope ratios of lynx muscle tissue spanning a cyclic increase and decline in hare density (1998-2001) in Fort Providence, NT, Canada. We found that lynx cohorts responded differently to hare population change, with yearling animals having broader diets at low hare densities, while adults and dependent juveniles maintained a constant diet through the initial decline in hare density. This result was consistent irrespective of lynx sex and indicates that yearling lynx likely are forced to adopt a broader diet when primary prey densities decline. Our results imply that select cohorts of specialist carnivores can exhibit high dietary plasticity in response to changes in primary prey abundance, prompting the need to determine whether increased diet breadth in young lynx is a successful strategy for surviving through periods of snowshoe hare scarcity. In this way, cohort-specific niche expansion could strongly affect the dynamics of organisms exhibiting population cycles. PMID:27648249

  4. Demographic differences in diet breadth of Canada lynx during a fluctuation in prey availability.

    PubMed

    Burstahler, Christa M; Roth, James D; Gau, Robert J; Murray, Dennis L

    2016-09-01

    Population dynamics of specialist carnivores are closely linked to prey availability, but the extent of variability in diet breadth of individual carnivores relative to natural variability in the abundance of their primary prey is not well understood. Canada lynx (Lynx canadensis) specialize on snowshoe hares (Lepus americanus) and exhibit cyclic fluctuations in abundance that lag 1-2 years behind those of snowshoe hares. Declining hare densities spur demographic changes in lynx, but it is unclear whether a corresponding increase in diet breadth occurs: (1) broadly across a lynx population; (2) only among individuals who are able to effectively switch to alternative prey; or (3) only among individuals who cannot capture sufficient primary prey. We measured stable isotope ratios of lynx muscle tissue spanning a cyclic increase and decline in hare density (1998-2001) in Fort Providence, NT, Canada. We found that lynx cohorts responded differently to hare population change, with yearling animals having broader diets at low hare densities, while adults and dependent juveniles maintained a constant diet through the initial decline in hare density. This result was consistent irrespective of lynx sex and indicates that yearling lynx likely are forced to adopt a broader diet when primary prey densities decline. Our results imply that select cohorts of specialist carnivores can exhibit high dietary plasticity in response to changes in primary prey abundance, prompting the need to determine whether increased diet breadth in young lynx is a successful strategy for surviving through periods of snowshoe hare scarcity. In this way, cohort-specific niche expansion could strongly affect the dynamics of organisms exhibiting population cycles.

  5. Levels of chlorinated, brominated, and perfluorinated contaminants in birds of prey spanning multiple trophic levels.

    PubMed

    Yordy, Jennifer E; Rossman, Sam; Ostrom, Peggy H; Reiner, Jessica L; Bargnesi, Keely; Hughes, Stacy; Elliot, James D

    2013-04-01

    Birds of prey occupy high trophic levels and can consequently bioaccumulate high levels of environmental contaminants. To evaluate exposure to past- and current-use pollutants, we measured legacy contaminants (i.e., polychlorinated biphenyls [PCBs]; organochlorine pesticides, e.g., DDT), contaminants of emerging concern (polybrominated diphenyl ethers [PBDEs]; perfluorinated compounds [PFCs]), and stable isotopes (δ(13)C, δ(15)N) in 26 birds of prey (10 species) from coastal South Carolina (USA) sampled in 2009 and 2010. Nitrogen isotope ratios (δ(15)N) ranged from 5.2% to 13.7%, indicating the birds of prey spanned two to three trophic levels. Legacy contaminant levels were highly variable but generally comparable to levels reported previously for birds of prey in the southeast US, suggesting exposure has not declined substantially over the past 40 yr. Despite their status as newly emerging environmental contaminants, PFC levels were within the same order of magnitude as legacy contaminants. Although PBDEs were less prevalent, levels were among the greatest observed in wildlife to date (∑PBDEs max. 200 μg/g lipid). Relative contaminant profiles also varied between birds of prey utilizing low and high trophic levels; specifically PFCs contributed to a larger proportion of the contaminant burden in birds utilizing high trophic levels, whereas the legacy pesticide mirex was a larger contributor in low-trophic-level birds, indicating that relative exposure is in part dependent on foraging ecology. This study demonstrates that birds of prey continue to face exposure to legacy contaminants as well as newly emerging contaminants at levels of concern. PMID:23568910

  6. Nonadditive impacts of temperature and basal resource availability on predator-prey interactions and phenotypes.

    PubMed

    Costa, Zacharia J; Kishida, Osamu

    2015-08-01

    Predicting the impacts of climate change on communities requires understanding how temperature affects predator-prey interactions under different biotic conditions. In cases of size-specific predation, environmental influences on the growth rate of one or both species can determine predation rates. For example, warming increases top-down control of food webs, although this depends on resource availability for prey, as increased resources may allow prey to reach a size refuge. Moreover, because the magnitude of inducible defenses depends on predation rates and resource availability for prey, temperature and resource levels also affect phenotypic plasticity. To examine these issues, we manipulated the presence/absence of predatory Hynobius retardatus salamander larvae and herbivorous Rana pirica tadpoles at two temperatures and three basal resource levels. and measured their morphology, behavior, growth and survival. Prior work has shown that both species express antagonistic plasticity against one another in which salamanders enlarge their gape width and tadpoles increase their body width to reach a size-refuge. We found that increased temperatures increased predation rates, although this was counteracted by high basal resource availability, which further decreased salamander growth. Surprisingly, salamanders caused tadpoles to grow larger and express more extreme defensive phenotypes as resource levels decreased under warming, most likely due to their increased risk of predation. Thus, temperature and resources influenced defensive phenotype expression and its impacts on predator and prey growth by affecting their interaction strength. Our results indicate that basal resource levels can modify the impacts of increased temperatures on predator-prey interactions and its consequences for food webs.

  7. Plastic Responses of a Sessile Prey to Multiple Predators: A Field and Experimental Study

    PubMed Central

    Hirsch, Philipp Emanuel; Cayon, David; Svanbäck, Richard

    2014-01-01

    Background Theory predicts that prey facing a combination of predators with different feeding modes have two options: to express a response against the feeding mode of the most dangerous predator, or to express an intermediate response. Intermediate phenotypes protect equally well against several feeding modes, rather than providing specific protection against a single predator. Anti-predator traits that protect against a common feeding mode displayed by all predators should be expressed regardless of predator combination, as there is no need for trade-offs. Principal Findings We studied phenotypic anti-predator responses of zebra mussels to predation threat from a handling-time-limited (crayfish) and a gape-size-limited (roach) predator. Both predators dislodge mussels from the substrate but diverge in their further feeding modes. Mussels increased expression of a non-specific defense trait (attachment strength) against all combinations of predators relative to a control. In response to roach alone, mussels showed a tendency to develop a weaker and more elongated shell. In response to crayfish, mussels developed a harder and rounder shell. When exposed to either a combination of predators or no predator, mussels developed an intermediate phenotype. Mussel growth rate was positively correlated with an elongated weaker shell and negatively correlated with a round strong shell, indicating a trade-off between anti-predator responses. Field observations of prey phenotypes revealed the presence of both anti-predator phenotypes and the trade-off with growth, but intra-specific population density and bottom substrate had a greater influence than predator density. Conclusions Our results show that two different predators can exert both functionally equivalent and inverse selection pressures on a single prey. Our field study suggests that abiotic factors and prey population density should be considered when attempting to explain phenotypic diversity in the wild. PMID

  8. A Measure of the Forest Protected Areas Benefits for the Surrounding Population: A Case Study of the Bouaflé Protected Forest (CÔTE D'IVOIRE)

    NASA Astrophysics Data System (ADS)

    Kouame, B. N. P.

    2015-12-01

    Côte d'Ivoire located in West Africa, registers high level of biodiversity which occurs mainly in forest land. The country has suffered severe deforestation. However, deforestation and forest degradation release Greenhouse Gases into the atmosphere which contributes to Climate Change. In order to address the deforestation, many actions are taken, one of which is the implementation of protected areas within countries. These measures put restrictions on the access of local communities to forest services. However, local communities supplement their daily livelihood from forests, especially from timber and non-timber forest products. What are the effects of forests conservation in protected areas on surrounding population? This study focuses on the Bouaflé protected forest (foret classée de Bouaflé) in the western part of Côte d'Ivoire. The forest is 20350 ha and was made a protected forest in 1974. It is one of the most deforested protected areas in the country. Firstly, we described the perception of forest benefits by the population. Secondly, we estimated the benefits of forest conservation using a contingent valuation approach, particularly the Willingness to Pay (WTP) methodology. From our sample size of 156 households, it appears that most of the individuals are aware of the importance of the forest (94 % against 6%). According to the estimate of the benefits, it results on average, people are willing to pay 1658.491F CFA (2.53 Euros). The median WTP is 1000 FCFA. This study will be helpful by adding to the scientific literature and for inducing local people implication in conservation.

  9. The biomechanics of fast prey capture in aquatic bladderworts.

    PubMed

    Singh, Amit K; Prabhakar, Sunil; Sane, Sanjay P

    2011-08-23

    Carnivorous plants match their animal prey for speed of movements and hence offer fascinating insights into the evolution of fast movements in plants. Here, we describe the mechanics of prey capture in aquatic bladderworts Utricularia stellaris, which prey on swimming insect larvae or nematodes to supplement their nitrogen intake. The closed Utricularia bladder develops lower-than-ambient internal pressures by pumping out water from the bladder and thus setting up an elastic instability in bladder walls. When the external sensory trigger hairs on their trapdoor are mechanically stimulated by moving prey, the trapdoor opens within 300-700 μs, causing strong inward flows that trap their prey. The opening time of the bladder trapdoor is faster than any recorded motion in carnivorous plants. Thus, Utricularia have evolved a unique biomechanical system to gain an advantage over their animal prey. PMID:21389013

  10. Nonconsumptive predator-driven mortality causes natural selection on prey.

    PubMed

    Siepielski, Adam M; Wang, Jason; Prince, Garrett

    2014-03-01

    Predators frequently exert natural selection through differential consumption of their prey. However, predators may also cause prey mortality through nonconsumptive effects, which could cause selection if different prey phenotypes are differentially susceptible to this nonconsumptive mortality. Here we present an experimental test of this hypothesis, which reveals that nonconsumptive mortality imposed by predatory dragonflies causes selection on their damselfly prey favoring increased activity levels. These results are consistent with other studies of predator-driven selection, however, they reveal that consumption alone is not the only mechanism by which predators can exert selection on prey. Uncovering this mechanism also suggests that prey defensive traits may represent adaptations to not only avoid being consumed, but also for dealing with other sources of mortality caused by predators. Demonstrating selection through both consumptive and nonconsumptive predator mortality provides us with insight into the diverse effects of predators as an evolutionary force.

  11. The biomechanics of fast prey capture in aquatic bladderworts.

    PubMed

    Singh, Amit K; Prabhakar, Sunil; Sane, Sanjay P

    2011-08-23

    Carnivorous plants match their animal prey for speed of movements and hence offer fascinating insights into the evolution of fast movements in plants. Here, we describe the mechanics of prey capture in aquatic bladderworts Utricularia stellaris, which prey on swimming insect larvae or nematodes to supplement their nitrogen intake. The closed Utricularia bladder develops lower-than-ambient internal pressures by pumping out water from the bladder and thus setting up an elastic instability in bladder walls. When the external sensory trigger hairs on their trapdoor are mechanically stimulated by moving prey, the trapdoor opens within 300-700 μs, causing strong inward flows that trap their prey. The opening time of the bladder trapdoor is faster than any recorded motion in carnivorous plants. Thus, Utricularia have evolved a unique biomechanical system to gain an advantage over their animal prey.

  12. Nash Equilibria in Noncooperative Predator-Prey Games

    SciTech Connect

    Ramos, Angel Manuel Roubicek, Tomas

    2007-09-15

    A noncooperative game governed by a distributed-parameter predator-prey system is considered, assuming that two players control initial conditions for predator and prey, respectively. Existence of a Nash equilibrium is shown under the condition that the desired population profiles and the environmental carrying capacity for the prey are sufficiently small. A conceptual approximation algorithm is proposed and analyzed. Finally, numerical simulations are performed, too.

  13. Molecular prey identification in Central European piscivores.

    PubMed

    Thalinger, Bettina; Oehm, Johannes; Mayr, Hannes; Obwexer, Armin; Zeisler, Christiane; Traugott, Michael

    2016-01-01

    Diet analysis is an important aspect when investigating the ecology of fish-eating animals and essential for assessing their functional role in food webs across aquatic and terrestrial ecosystems. The identification of fish remains in dietary samples, however, can be time-consuming and unsatisfying using conventional morphological analysis of prey remains. Here, we present a two-step multiplex PCR system, comprised of six assays, allowing for rapid, sensitive and specific detection of fish DNA in dietary samples. This approach encompasses 78 fish and lamprey species native to Central European freshwaters and enables the identification of 31 species, six genera, two families, two orders and two fish family clusters. All targeted taxa were successfully amplified from 25 template molecules, and each assay was specific when tested against a wide range of invertebrates and vertebrates inhabiting aquatic environments. The applicability of the multiplex PCR system was evaluated in a feeding trial, wherein it outperformed morphological prey analysis regarding species-specific prey identification in faeces of Eurasian otters. Additionally, a wide spectrum of fish species was detected in field-collected faecal samples and regurgitated pellets of Common Kingfishers and Great Cormorants, demonstrating the broad applicability of the approach. In conclusion, this multiplex PCR system provides an efficient, easy to use and cost-effective tool for assessing the trophic ecology of piscivores in Central Europe. Furthermore, the multiplex PCRs and the primers described therein will be applicable wherever DNA of the targeted fish species needs to be detected at high sensitivity and specificity. PMID:26053612

  14. Measuring Community Risk and Protective Factors for Adolescent Problem Behaviors: Evidence from a Developing Nation

    ERIC Educational Resources Information Center

    Maguire, Edward R.; Wells, William; Katz, Charles M.

    2011-01-01

    Most published research on community risk and protective factors for adolescent problem behaviors has been carried out in developed nations. This article examines community risk and protective factors in a sample of more than 2,500 adolescents in Trinidad and Tobago, a developing Caribbean nation. The authors examine the construct and concurrent…

  15. Early Cretaceous spider web with its prey.

    PubMed

    Peñalver, Enrique; Grimaldi, David A; Delclòs, Xavier

    2006-06-23

    The orb web is a spectacular evolutionary innovation that enables spiders to catch flying prey. This elegant, geometric structure is woven with silk fibers that are renowned for their superior mechanical properties. We used silk gland expression libraries to address a long-standing controversy concerning the evolution of the orb-web architecture. Contrary to the view that the orb-web design evolved multiple times, we found that the distribution and phylogeny of silk proteins support a single, ancient origin of the orb web at least 136 million years ago. Furthermore, we substantially expanded the repository of silk sequences that can be used for the synthesis of high-performance biomaterials.

  16. Assassin bug uses aggressive mimicry to lure spider prey.

    PubMed

    Wignall, Anne E; Taylor, Phillip W

    2011-05-01

    Assassin bugs (Stenolemus bituberus) hunt web-building spiders by invading the web and plucking the silk to generate vibrations that lure the resident spider into striking range. To test whether vibrations generated by bugs aggressively mimic the vibrations generated by insect prey, we compared the responses of spiders to bugs with how they responded to prey, courting male spiders and leaves falling into the web. We also analysed the associated vibrations. Similar spider orientation and approach behaviours were observed in response to vibrations from bugs and prey, whereas different behaviours were observed in response to vibrations from male spiders and leaves. Peak frequency and duration of vibrations generated by bugs were similar to those generated by prey and courting males. Further, vibrations from bugs had a temporal structure and amplitude that were similar to vibrations generated by leg and body movements of prey and distinctly different to vibrations from courting males or leaves, or prey beating their wings. To be an effective predator, bugs do not need to mimic the full range of prey vibrations. Instead bugs are general mimics of a subset of prey vibrations that fall within the range of vibrations classified by spiders as 'prey'.

  17. Prey processing in the Siamese fighting fish (Betta splendens).

    PubMed

    Konow, Nicolai; Krijestorac, Belma; Sanford, Christopher P J; Boistel, Renauld; Herrel, Anthony

    2013-07-01

    We studied prey processing in the Siamese fighting fish (Betta splendens), involving slow, easily observed head-bobbing movements, which were compared with prey processing in other aquatic feeding vertebrates. We hypothesized that head-bobbing is a unique prey-processing behaviour, which alternatively could be structurally and functionally analogous with raking in basal teleosts, or with pharyngognathy in neoteleosts. Modulation of head-bobbing was elicited by prey with different motility and toughness. Head-bobbing involved sustained mouth occlusion and pronounced cranial elevation, similar to raking. However, the hyoid and pectoral girdle were protracted, and not retracted as in both raking and pharyngognathy. High-speed videofluoroscopy of hyoid movements confirmed that head-bobbing differs from other known aquatic prey-processing behaviours. Nevertheless, head-bobbing and other prey-processing behaviours converge on a recurrent functional theme in the trophic ecology of aquatic feeding vertebrates; the use of intraoral and oropharyngeal dentition surfaces to immobilize, reduce and process relatively large, tough or motile prey. Prey processing outside the pharyngeal region has not been described for neoteleosts previously, but morphological evidence suggests that relatives of Betta might use similar processing behaviours. Thus, our results suggest that pharyngognathy did not out-compete ancestral prey-processing mechanisms completely during the evolution of neoteleosts.

  18. Alternative prey use affects helminth parasite infections in grey wolves.

    PubMed

    Friesen, Olwyn C; Roth, James D

    2016-09-01

    Predators affect prey populations not only through direct predation, but also by acting as definitive hosts for their parasites and completing parasite life cycles. Understanding the affects of parasitism on prey population dynamics requires knowing how their predators' parasite community is affected by diet and prey availability. Ungulates, such as moose (Alces americanus) and white-tailed deer (Odocoileus virginianus), are often important prey for wolves (Canis lupus), but wolves also consume a variety of alternative prey, including beaver (Castor canadensis) and snowshoe hare (Lepus americanus). The use of alternative prey, which may host different or fewer parasites than ungulates, could potentially reduce overall abundance of ungulate parasites within the ecosystem, benefiting both wolves and ungulate hosts. We examined parasites in wolf carcasses from eastern Manitoba and estimated wolf diet using stable isotope analysis. Taeniidae cestodes were present in most wolves (75%), reflecting a diet primarily comprised of ungulates, but nematodes were unexpectedly rare. Cestode abundance was negatively related to the wolf's δ(13) C value, indicating diet affects parasite abundance. Wolves that consumed a higher proportion of beaver and caribou (Rangifer tarandus), estimated using Bayesian mixing models, had lower cestode abundance, suggesting the use of these alternative prey can reduce parasite loads. Long-term consumption of beavers may lower the abundance of adult parasites in wolves, eventually lowering parasite density in the region and ultimately benefiting ungulates that serve as intermediate hosts. Thus, alternative prey can affect both predator-prey and host-parasite interactions and potentially affect food web dynamics.

  19. Assassin bug uses aggressive mimicry to lure spider prey.

    PubMed

    Wignall, Anne E; Taylor, Phillip W

    2011-05-01

    Assassin bugs (Stenolemus bituberus) hunt web-building spiders by invading the web and plucking the silk to generate vibrations that lure the resident spider into striking range. To test whether vibrations generated by bugs aggressively mimic the vibrations generated by insect prey, we compared the responses of spiders to bugs with how they responded to prey, courting male spiders and leaves falling into the web. We also analysed the associated vibrations. Similar spider orientation and approach behaviours were observed in response to vibrations from bugs and prey, whereas different behaviours were observed in response to vibrations from male spiders and leaves. Peak frequency and duration of vibrations generated by bugs were similar to those generated by prey and courting males. Further, vibrations from bugs had a temporal structure and amplitude that were similar to vibrations generated by leg and body movements of prey and distinctly different to vibrations from courting males or leaves, or prey beating their wings. To be an effective predator, bugs do not need to mimic the full range of prey vibrations. Instead bugs are general mimics of a subset of prey vibrations that fall within the range of vibrations classified by spiders as 'prey'. PMID:20980305

  20. Model of naticid gastropod predator-prey coevolution

    SciTech Connect

    DeAngelis, D.L.; Kitchell, J.A.; Post, W.M.; Travis, C.C.

    1982-01-01

    Size change over evolutionary time between two interacting species, a predatory naticid gastropod and its bivalve prey, is analyzed. We show that two simultaneous, maximizing algorithms (the predator maximizes energy intake; the prey maximizes reproductive output) result in an endogenous, coevolutionary size increase, to a stable attracting point. In particular, we show that selection for delayed reproduction in a predatorpreay system that is highly size-selective due to the predatory strategy of cost-benefit prey selection, coupled with the relative allometries of cost (prey shell thickness) and benefit (prey biomass) with prey size, and the highly size-dependent probability of successful predation, lead to a coevolutionary size increase for both predator and prey, up to a limit condition dictated by predatory respiration costs. In the absence of predation, the prey species attains a smaller size than in the presence of predation. Addition of the predator results in a delay in the timing of reproduction by the prey, thereby facilitating a size response.

  1. Prey processing in the Siamese fighting fish (Betta splendens).

    PubMed

    Konow, Nicolai; Krijestorac, Belma; Sanford, Christopher P J; Boistel, Renauld; Herrel, Anthony

    2013-07-01

    We studied prey processing in the Siamese fighting fish (Betta splendens), involving slow, easily observed head-bobbing movements, which were compared with prey processing in other aquatic feeding vertebrates. We hypothesized that head-bobbing is a unique prey-processing behaviour, which alternatively could be structurally and functionally analogous with raking in basal teleosts, or with pharyngognathy in neoteleosts. Modulation of head-bobbing was elicited by prey with different motility and toughness. Head-bobbing involved sustained mouth occlusion and pronounced cranial elevation, similar to raking. However, the hyoid and pectoral girdle were protracted, and not retracted as in both raking and pharyngognathy. High-speed videofluoroscopy of hyoid movements confirmed that head-bobbing differs from other known aquatic prey-processing behaviours. Nevertheless, head-bobbing and other prey-processing behaviours converge on a recurrent functional theme in the trophic ecology of aquatic feeding vertebrates; the use of intraoral and oropharyngeal dentition surfaces to immobilize, reduce and process relatively large, tough or motile prey. Prey processing outside the pharyngeal region has not been described for neoteleosts previously, but morphological evidence suggests that relatives of Betta might use similar processing behaviours. Thus, our results suggest that pharyngognathy did not out-compete ancestral prey-processing mechanisms completely during the evolution of neoteleosts. PMID:23612845

  2. Alternative prey use affects helminth parasite infections in grey wolves.

    PubMed

    Friesen, Olwyn C; Roth, James D

    2016-09-01

    Predators affect prey populations not only through direct predation, but also by acting as definitive hosts for their parasites and completing parasite life cycles. Understanding the affects of parasitism on prey population dynamics requires knowing how their predators' parasite community is affected by diet and prey availability. Ungulates, such as moose (Alces americanus) and white-tailed deer (Odocoileus virginianus), are often important prey for wolves (Canis lupus), but wolves also consume a variety of alternative prey, including beaver (Castor canadensis) and snowshoe hare (Lepus americanus). The use of alternative prey, which may host different or fewer parasites than ungulates, could potentially reduce overall abundance of ungulate parasites within the ecosystem, benefiting both wolves and ungulate hosts. We examined parasites in wolf carcasses from eastern Manitoba and estimated wolf diet using stable isotope analysis. Taeniidae cestodes were present in most wolves (75%), reflecting a diet primarily comprised of ungulates, but nematodes were unexpectedly rare. Cestode abundance was negatively related to the wolf's δ(13) C value, indicating diet affects parasite abundance. Wolves that consumed a higher proportion of beaver and caribou (Rangifer tarandus), estimated using Bayesian mixing models, had lower cestode abundance, suggesting the use of these alternative prey can reduce parasite loads. Long-term consumption of beavers may lower the abundance of adult parasites in wolves, eventually lowering parasite density in the region and ultimately benefiting ungulates that serve as intermediate hosts. Thus, alternative prey can affect both predator-prey and host-parasite interactions and potentially affect food web dynamics. PMID:27155132

  3. Prey community structure affects how predators select for Mullerian mimicry.

    PubMed

    Ihalainen, Eira; Rowland, Hannah M; Speed, Michael P; Ruxton, Graeme D; Mappes, Johanna

    2012-06-01

    Müllerian mimicry describes the close resemblance between aposematic prey species; it is thought to be beneficial because sharing a warning signal decreases the mortality caused by sampling by inexperienced predators learning to avoid the signal. It has been hypothesized that selection for mimicry is strongest in multi-species prey communities where predators are more prone to misidentify the prey than in simple communities. In this study, wild great tits (Parus major) foraged from either simple (few prey appearances) or complex (several prey appearances) artificial prey communities where a specific model prey was always present. Owing to slower learning, the model did suffer higher mortality in complex communities when the birds were inexperienced. However, in a subsequent generalization test to potential mimics of the model prey (a continuum of signal accuracy), only birds that had foraged from simple communities selected against inaccurate mimics. Therefore, accurate mimicry is more likely to evolve in simple communities even though predator avoidance learning is slower in complex communities. For mimicry to evolve, prey species must have a common predator; the effective community consists of the predator's diet. In diverse environments, the limited diets of specialist predators could create 'simple community pockets' where accurate mimicry is selected for.

  4. Energy density and variability in abundance of pigeon guillemot prey: Support for the quality-variability trade-off hypothesis

    USGS Publications Warehouse

    Litzow, M.A.; Piatt, J.F.; Abookire, A.A.; Robards, M.D.

    2004-01-01

    1. The quality-variability trade-off hypothesis predicts that (i) energy density (kJ g-1) and spatial-temporal variability in abundance are positively correlated in nearshore marine fishes; and (ii) prey selection by a nearshore piscivore, the pigeon guillemot (Cepphus columba Pallas), is negatively affected by variability in abundance. 2. We tested these predictions with data from a 4-year study that measured fish abundance with beach seines and pigeon guillemot prey utilization with visual identification of chick meals. 3. The first prediction was supported. Pearson's correlation showed that fishes with higher energy density were more variable on seasonal (r = 0.71) and annual (r = 0.66) time scales. Higher energy density fishes were also more abundant overall (r = 0.85) and more patchy at a scale of 10s of km (r = 0.77). 4. Prey utilization by pigeon guillemots was strongly non-random. Relative preference, defined as the difference between log-ratio transformed proportions of individual prey taxa in chick diets and beach seine catches, was significantly different from zero for seven of the eight main prey categories. 5. The second prediction was also supported. We used principal component analysis (PCA) to summarize variability in correlated prey characteristics (energy density, availability and variability in abundance). Two PCA scores explained 32% of observed variability in pigeon guillemot prey utilization. Seasonal variability in abundance was negatively weighted by these PCA scores, providing evidence of risk-averse selection. Prey availability, energy density and km-scale variability in abundance were positively weighted. 6. Trophic interactions are known to create variability in resource distribution in other systems. We propose that links between resource quality and the strength of trophic interactions may produce resource quality-variability trade-offs.

  5. Environmental chemical cues associated with prey and subsequent prey preference in the wolf spider Hogna carolinensis Hentz (Araneae, Lycosidae).

    PubMed

    Punzo, F; Preshkar, C

    2002-10-01

    The purpose of this study was to determine if environmental chemical cues associated with prey can affect subsequent prey choice in wolf spiderlings (Hogna carolinensis). After emergence from the egg sac, three groups of 10 spiderlings were each fed for one-week on one of three naturally-occurring prey species: group 1 fed on nymphs of the field cricket Gryllus pennsylvanicus; group 2 (house cricket, Acheta domesticus); group 3 (mole cricket, Gryllotalpa hexadactyla). They were then tested for subsequent prey preference in choice tests conducted in a plastic arena. Each spiderlings was presented simultaneously with one individual of each prey species in a randomized design. Spiderlings exhibited a significant first preference for the original diet. Thus, experience with certain foods (environmental chemical cues) encountered by newly hatched spiderlings can affect subsequent prey preference in this species.

  6. Fine-tuned echolocation and capture-flight of Myotis capaccinii when facing different-sized insect and fish prey.

    PubMed

    Aizpurua, Ostaizka; Aihartza, Joxerra; Alberdi, Antton; Baagøe, Hans J; Garin, Inazio

    2014-09-15

    Formerly thought to be a strictly insectivorous trawling bat, recent studies have shown that Myotis capaccinii also preys on fish. To determine whether differences exist in bat flight behaviour, prey handling and echolocation characteristics when catching fish and insects of different size, we conducted a field experiment focused on the last stage of prey capture. We used synchronized video and ultrasound recordings to measure several flight and dip features as well as echolocation characteristics, focusing on terminal buzz phase I, characterized by a call rate exceeding 100 Hz, and buzz phase II, characterized by a drop in the fundamental well below 20 kHz and a repetition rate exceeding 150 Hz. When capturing insects, bats used both parts of the terminal phase to the same extent, and performed short and superficial drags on the water surface. In contrast, when preying on fish, buzz I was longer and buzz II shorter, and the bats made longer and deeper dips. These variations suggest that lengthening buzz I and shortening buzz II when fishing is beneficial, probably because buzz I gives better discrimination ability and the broader sonar beam provided by buzz II is useless when no evasive flight of the prey is expected. Additionally, bats continued emitting calls beyond the theoretical signal-overlap zone, suggesting that they might obtain information even when they have surpassed that threshold, at least initially. This study shows that M. capaccinii can regulate the temporal components of its feeding buzzes and modify prey capture technique according to the target.

  7. Fine-tuned echolocation and capture-flight of Myotis capaccinii when facing different-sized insect and fish prey.

    PubMed

    Aizpurua, Ostaizka; Aihartza, Joxerra; Alberdi, Antton; Baagøe, Hans J; Garin, Inazio

    2014-09-15

    Formerly thought to be a strictly insectivorous trawling bat, recent studies have shown that Myotis capaccinii also preys on fish. To determine whether differences exist in bat flight behaviour, prey handling and echolocation characteristics when catching fish and insects of different size, we conducted a field experiment focused on the last stage of prey capture. We used synchronized video and ultrasound recordings to measure several flight and dip features as well as echolocation characteristics, focusing on terminal buzz phase I, characterized by a call rate exceeding 100 Hz, and buzz phase II, characterized by a drop in the fundamental well below 20 kHz and a repetition rate exceeding 150 Hz. When capturing insects, bats used both parts of the terminal phase to the same extent, and performed short and superficial drags on the water surface. In contrast, when preying on fish, buzz I was longer and buzz II shorter, and the bats made longer and deeper dips. These variations suggest that lengthening buzz I and shortening buzz II when fishing is beneficial, probably because buzz I gives better discrimination ability and the broader sonar beam provided by buzz II is useless when no evasive flight of the prey is expected. Additionally, bats continued emitting calls beyond the theoretical signal-overlap zone, suggesting that they might obtain information even when they have surpassed that threshold, at least initially. This study shows that M. capaccinii can regulate the temporal components of its feeding buzzes and modify prey capture technique according to the target. PMID:25013107

  8. The Coevolution of "Tyrannosaurus" & Its Prey: Could "Tyrannosaurus" Chase down & Kill a "Triceratops" for Lunch?

    ERIC Educational Resources Information Center

    May, S. Randolph

    2014-01-01

    Students will analyze the coevolution of the predator-prey relationships between "Tyrannosaurus rex" and its prey species using analyses of animal speeds from fossilized trackways, prey-animal armaments, adaptive behaviors, bite marks on prey-animal fossils, predator-prey ratios, and scavenger competition. The students will be asked to…

  9. Global existence of solutions and uniform persistence of a diffusive predator-prey model with prey-taxis

    NASA Astrophysics Data System (ADS)

    Wu, Sainan; Shi, Junping; Wu, Boying

    2016-04-01

    This paper proves the global existence and boundedness of solutions to a general reaction-diffusion predator-prey system with prey-taxis defined on a smooth bounded domain with no-flux boundary condition. The result holds for domains in arbitrary spatial dimension and small prey-taxis sensitivity coefficient. This paper also proves the existence of a global attractor and the uniform persistence of the system under some additional conditions. Applications to models from ecology and chemotaxis are discussed.

  10. Variation in prey selection of a piscivorous fish after the impoundment of a neotropical reservoir: prey size and type.

    PubMed

    Cantanhêde, G; Fugi, R; Hahn, N S

    2009-07-01

    The relative abundance and size of prey fish in the stomachs of the predator Acestrorhynchus pantaneiro were compared with those recorded in the field to estimate prey selection. Fish samples were taken monthly in the Manso Reservoir (State of Mato Grosso, Brazil) immediately after the impoundment, from March 2000 to February 2001 (period I) and from March 2003 to February 2004 (period II). In period I, the small relative dominance of the prey in the environment seemed to have lead to random foraging. In period II, however, when the forage fish Moenkhausia dichroura was dominant in the environment, the predator shifted its diet, foraging mainly on this prey. Species with short relative body depth were positively selected. The prey size classes between 30 and 49 mm, and 50 and 69 mm standard length (L(S)) were the most abundant in the environment. Small prey were predominantly selected by A. pantaneiro. Even when a given prey or prey size was predominant in the environment, A. pantaneiro was a selective predator and maintained its preferences associated to prey type and L(S), although it consumed the most abundant resource. PMID:20738483

  11. Item Randomized-Response Models for Measuring Noncompliance: Risk-Return Perceptions, Social Influences, and Self-Protective Responses

    ERIC Educational Resources Information Center

    Bockenholt, Ulf; Van Der Heijden, Peter G. M.

    2007-01-01

    Randomized response (RR) is a well-known method for measuring sensitive behavior. Yet this method is not often applied because: (i) of its lower efficiency and the resulting need for larger sample sizes which make applications of RR costly; (ii) despite its privacy-protection mechanism the RR design may not be followed by every respondent; and…

  12. 75 FR 81921 - Fisheries of the Exclusive Economic Zone Off Alaska; Steller Sea Lion Protection Measures for the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-29

    ... published in the Federal Register on December 13, 2010 (75 FR 77535), to implement Steller sea lion... corrections revise coordinates for Steller sea lion sites, revise footnotes, add degree symbols, add lines... Economic Zone Off Alaska; Steller Sea Lion Protection Measures for the Bering Sea and Aleutian...

  13. David and Goliath: potent venom of an ant-eating spider (Araneae) enables capture of a giant prey

    NASA Astrophysics Data System (ADS)

    Pekár, Stano; Šedo, Onřej; Líznarová, Eva; Korenko, Stanislav; Zdráhal, Zdeněk

    2014-07-01

    It is rare to find a true predator that repeatedly and routinely kills prey larger than itself. A solitary specialised ant-eating spider of the genus Zodarion can capture a relatively giant prey. We studied the trophic niche of this spider species and investigated its adaptations (behavioural and venomic) that are used to capture ants. We found that the spider captures mainly polymorphic Messor arenarius ants. Adult female spiders captured large morphs while tiny juveniles captured smaller morphs, yet in both cases ants were giant in comparison with spider size. All specimens used an effective prey capture strategy that protected them from ant retaliation. Juvenile and adult spiders were able to paralyse their prey using a single bite. The venom glands of adults were more than 50 times larger than those of juvenile spiders, but the paralysis latency of juveniles was 1.5 times longer. This suggests that this spider species possesses very potent venom already at the juvenile stage. Comparison of the venom composition between juvenile and adult spiders did not reveal significant differences. We discovered here that specialised capture combined with very effective venom enables the capture of giant prey.

  14. David and Goliath: potent venom of an ant-eating spider (Araneae) enables capture of a giant prey.

    PubMed

    Pekár, Stano; Šedo, Onřej; Líznarová, Eva; Korenko, Stanislav; Zdráhal, Zdeněk

    2014-07-01

    It is rare to find a true predator that repeatedly and routinely kills prey larger than itself. A solitary specialised ant-eating spider of the genus Zodarion can capture a relatively giant prey. We studied the trophic niche of this spider species and investigated its adaptations (behavioural and venomic) that are used to capture ants. We found that the spider captures mainly polymorphic Messor arenarius ants. Adult female spiders captured large morphs while tiny juveniles captured smaller morphs, yet in both cases ants were giant in comparison with spider size. All specimens used an effective prey capture strategy that protected them from ant retaliation. Juvenile and adult spiders were able to paralyse their prey using a single bite. The venom glands of adults were more than 50 times larger than those of juvenile spiders, but the paralysis latency of juveniles was 1.5 times longer. This suggests that this spider species possesses very potent venom already at the juvenile stage. Comparison of the venom composition between juvenile and adult spiders did not reveal significant differences. We discovered here that specialised capture combined with very effective venom enables the capture of giant prey.

  15. Rarity of a top predator triggers continent-wide collapse of mammal prey: dingoes and marsupials in Australia.

    PubMed

    Johnson, Christopher N; Isaac, Joanne L; Fisher, Diana O

    2007-02-01

    Top predators in terrestrial ecosystems may limit populations of smaller predators that could otherwise become over abundant and cause declines and extinctions of some prey. It is therefore possible that top predators indirectly protect many species of prey from excessive predation. This effect has been demonstrated in some small-scale studies, but it is not known how general or important it is in maintaining prey biodiversity. During the last 150 years, Australia has suffered the world's highest rate of mammal decline and extinction, and most evidence points to introduced mid-sized predators (the red fox and the feral cat) as the cause. Here, we test the idea that the decline of Australia's largest native predator, the dingo, played a role in these extinctions. Dingoes were persecuted from the beginning of European settlement in Australia and have been eliminated or made rare over large parts of the continent. We show a strong positive relationship between the survival of marsupials and the geographical overlap with high-density dingo populations. Our results suggest that the rarity of dingoes was a critical factor which allowed smaller predators to overwhelm marsupial prey, triggering extinction over much of the continent. This is evidence of a crucial role of top predators in maintaining prey biodiversity at large scales in terrestrial ecosystems and suggests that many remaining Australian mammals would benefit from the positive management of dingoes. PMID:17164197

  16. Evaluating prey switching in wolf-ungulate systems.

    PubMed

    Garrott, Robert A; Bruggeman, Jason E; Becker, Matthew S; Kalinowski, Steven T; White, P J

    2007-09-01

    Wolf restoration has become a widely accepted conservation and management practice throughout North America and Europe, though the ecosystem effects of returning top carnivores remain both scientific and societal controversies. Mathematical models predicting and describing wolf-ungulate interactions are typically limited to the wolves' primary prey, with the potential for prey switching in wolf-multiple-ungulate systems only suggested or assumed by a number of investigators. We used insights gained from experiments on small taxa and field data from ongoing wolf-ungulate studies to construct a model of predator diet composition for a wolf-elk-bison system in Yellowstone National Park, Wyoming, USA. The model explicitly incorporates differential vulnerability of the ungulate prey types to predation, predator preference, differences in prey biomass, and the possibility of prey switching. Our model demonstrates wolf diet shifts with changes in relative abundance of the two prey, with the dynamics of this shift dependent on the combined influences of preference, differential vulnerability, relative abundances of prey, and whether or not switching occurs. Differences in vulnerability between elk and bison, and strong wolf preference for elk, result in an abrupt dietary shift occurring only when elk are very rare relative to bison, whereas incorporating switching initiates the dietary shift more gradually and at higher bison-elk ratios. We demonstrate how researchers can apply these equations in newly restored wolf-two-prey systems to empirically evaluate whether prey switching is occurring. Each coefficient in the model has a biological interpretation, and most can be directly estimated from empirical data collected from field studies. Given the potential for switching to dramatically influence predator-prey dynamics and the wide range of expected prey types and abundances in some systems where wolves are present and/or being restored, we suggest that this is an

  17. 43 CFR 3162.7 - Measurement, disposition, and protection of production.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... of production. 3162.7 Section 3162.7 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) ONSHORE OIL AND..., disposition, and protection of production....

  18. 43 CFR 3162.7 - Measurement, disposition, and protection of production.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... of production. 3162.7 Section 3162.7 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) ONSHORE OIL AND..., disposition, and protection of production....

  19. 43 CFR 3162.7 - Measurement, disposition, and protection of production.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... of production. 3162.7 Section 3162.7 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) ONSHORE OIL AND..., disposition, and protection of production....

  20. Household-Level Expenditure on Protective Measures Against Mosquitoes on the Island of La Réunion, France

    PubMed Central

    Thuilliez, Josselin; Bellia, Claire; Dehecq, Jean-Sébastien; Reilhes, Olivier

    2014-01-01

    Background For decades La Réunion has experienced a number of epidemics that have resulted in efforts to control the density of Aedes species on this Island. This study was conducted to assess household-level expenditure on protective measures against mosquito nuisance on the Island of La Réunion in 2012. Methodology/Principal Findings Data was collected during a cross-sectional survey of 1024 households and used to determine the relationship between the use of chemically-based protective measures and subjective and objective indicators of the density of Aedes albopictus. The average household expenditure in July 2012 was USD 9.86 and the total household-level expenditure over a one-year period was extrapolated to USD 28.05million (range: USD 25.58 million to USD 30.76 million). Much of this money was spent on measures thought to be relatively ineffective against Aedes mosquitoes. Expenditure on protective measures was not influenced by the level of knowledge on mosquitoes or by the visual nuisance they generated at home, but rather by the perception of risk related to a future epidemic of chikungunya and socioeconomic factors. Most importantly, household spending on protective measures was found to be influenced by a measure of zone-level mosquito density (the Breteau index), but not by objective indicators of the presence of mosquitoes within or around the house. Conclusions/Significance Household-level expenditure on chemically-based protective measures is high when compared to the investment made by public entities to achieve vector control, and it is differentially influenced by subjective and objective measures of mosquito density. The current situation could be improved, firstly by ensuring that the public is well-informed about mosquitoes and the effectiveness of various protective measures, and secondly by implementing interventions that could either complement current vector-control strategies and improve their effectiveness on a country-level, or that

  1. Estimate of net trophic transfer efficiency of PCBs to Lake Michigan lake trout from their prey

    USGS Publications Warehouse

    Madenjian, Charles P.; Hesselberg, Robert J.; DeSorcie, Timothy J.; Schmidt, Larry J.; Stedman, Ralph M.; Quintal, Richard T.; Begnoche, Linda J.; Passino-Reader, Dora R.

    1998-01-01

    Most of the polychlorinated biphenyl (PCB) body burden accumulated by lake trout (Salvelinus namaycush) from the Laurentian Great Lakes is from their food. We used diet information, PCB determinations in both lake trout and their prey, and bioenergetics modeling to estimate the efficiency with which Lake Michigan lake trout retain PCBs from their food. Our estimates were the most reliable estimates to date because (a) the lake trout and prey fish sampled during our study were all from the same vicinity of the lake, (b) detailed measurements were made on the PCB concentrations of both lake trout and prey fish over wide ranges in fish size, and (c) lake trout diet was analyzed in detail over a wide range of lake trout size. Our estimates of net trophic transfer efficiency of PCBs to lake trout from their prey averaged from 0.73 to 0.89 for lake trout between the ages of 5 and 10 years old. There was no evidence of an upward or downward trend in our estimates of net trophic transfer efficiency for lake trout between the ages of 5 and 10 years old, and therefore this efficiency appeared to be constant over the duration of the lake trout's adult life in the lake. On the basis of our estimtes, lake trout retained 80% of the PCBs that are contained within their food.

  2. Dynamics of the echolocation beam during prey pursuit in aerial hawking bats.

    PubMed

    Jakobsen, Lasse; Olsen, Mads Nedergaard; Surlykke, Annemarie

    2015-06-30

    In the evolutionary arms race between prey and predator, measures and countermeasures continuously evolve to increase survival on both sides. Bats and moths are prime examples. When exposed to intense ultrasound, eared moths perform dramatic escape behaviors. Vespertilionid and rhinolophid bats broaden their echolocation beam in the final stage of pursuit, presumably as a countermeasure to keep evading moths within their "acoustic field of view." In this study, we investigated if dynamic beam broadening is a general property of echolocation when catching moving prey. We recorded three species of emballonurid bats, Saccopteryx bilineata, Saccopteryx leptura, and Rhynchonycteris naso, catching airborne insects in the field. The study shows that S. bilineata and S. leptura maintain a constant beam shape during the entire prey pursuit, whereas R. naso broadens the beam by lowering the peak call frequency from 100 kHz during search and approach to 67 kHz in the buzz. Surprisingly, both Saccopteryx bats emit calls with very high energy throughout the pursuit, up to 60 times more than R. naso and Myotis daubentonii (a similar sized vespertilionid), providing them with as much, or more, peripheral "vision" than the vespertilionids, but ensonifying objects far ahead suggesting more clutter. Thus, beam broadening is not a fundamental property of the echolocation system. However, based on the results, we hypothesize that increased peripheral detection is crucial to all aerial hawking bats in the final stages of prey pursuit and speculate that beam broadening is a feature characterizing more advanced echolocation.

  3. The diet of deepwater sharks and the benefits of using DNA identification of prey

    NASA Astrophysics Data System (ADS)

    Dunn, Matthew R.; Szabo, Ava; McVeagh, Margaret S.; Smith, Peter J.

    2010-07-01

    Stomachs from the sharks Dalatias licha, Centrophorus squamosus, Centroscymnus owstoni, Centroselachus crepidater, Proscymnodon plunketi, and Galeorhinus galeus were sampled from three research trawl surveys on Chatham Rise, east of New Zealand. Between 14 and 50 stomachs were examined for each species, of which 8-62% were empty. Prey were visually identified in 80 stomachs, and by DNA barcoding in a further 28 stomachs. The use of DNA methods allowed the identification of chunks of flesh found in the stomachs of D. licha and P. plunketi, and nearly doubled the rate of data accumulation for D. licha, C. squamosus, and C. owstoni. Between 84 and 223 stomachs were estimated to be needed to measure 90% of the extrapolated total prey richness. The prey of D. licha, C. squamosus, and P. plunketi were predominantly benthic or demersal fishes and cephalopods. The prey of C. owstoni and C. crepidater were predominantly mesopelagic fishes and squids. G. galeus foraged throughout the water column. Scavenging of discards from commercial fishing vessels was likely in C. squamosus, P. plunketi, and G. galeus. The diet of all species except C. crepidater was dominated by the commercially important benthopelagic species hoki Macruronus novaezelandiae.

  4. Dynamics of the echolocation beam during prey pursuit in aerial hawking bats.

    PubMed

    Jakobsen, Lasse; Olsen, Mads Nedergaard; Surlykke, Annemarie

    2015-06-30

    In the evolutionary arms race between prey and predator, measures and countermeasures continuously evolve to increase survival on both sides. Bats and moths are prime examples. When exposed to intense ultrasound, eared moths perform dramatic escape behaviors. Vespertilionid and rhinolophid bats broaden their echolocation beam in the final stage of pursuit, presumably as a countermeasure to keep evading moths within their "acoustic field of view." In this study, we investigated if dynamic beam broadening is a general property of echolocation when catching moving prey. We recorded three species of emballonurid bats, Saccopteryx bilineata, Saccopteryx leptura, and Rhynchonycteris naso, catching airborne insects in the field. The study shows that S. bilineata and S. leptura maintain a constant beam shape during the entire prey pursuit, whereas R. naso broadens the beam by lowering the peak call frequency from 100 kHz during search and approach to 67 kHz in the buzz. Surprisingly, both Saccopteryx bats emit calls with very high energy throughout the pursuit, up to 60 times more than R. naso and Myotis daubentonii (a similar sized vespertilionid), providing them with as much, or more, peripheral "vision" than the vespertilionids, but ensonifying objects far ahead suggesting more clutter. Thus, beam broadening is not a fundamental property of the echolocation system. However, based on the results, we hypothesize that increased peripheral detection is crucial to all aerial hawking bats in the final stages of prey pursuit and speculate that beam broadening is a feature characterizing more advanced echolocation. PMID:26080398

  5. Prey-mediated behavioral responses of feeding blue whales in controlled sound exposure experiments.

    PubMed

    Friedlaender, A S; Hazen, E L; Goldbogen, J A; Stimpert, A K; Calambokidis, J; Southall, B L

    2016-06-01

    Behavioral response studies provide significant insights into the nature, magnitude, and consequences of changes in animal behavior in response to some external stimulus. Controlled exposure experiments (CEEs) to study behavioral response have faced challenges in quantifying the importance of and interaction among individual variability, exposure conditions, and environmental covariates. To investigate these complex parameters relative to blue whale behavior and how it may change as a function of certain sounds, we deployed multi-sensor acoustic tags and conducted CEEs using simulated mid-frequency active sonar (MFAS) and pseudo-random noise (PRN) stimuli, while collecting synoptic, quantitative prey measures. In contrast to previous approaches that lacked such prey data, our integrated approach explained substantially more variance in blue whale dive behavioral responses to mid-frequency sounds (r2 = 0.725 vs. 0.14 previously). Results demonstrate that deep-feeding whales respond more clearly and strongly to CEEs than those in other behavioral states, but this was only evident with the increased explanatory power provided by incorporating prey density and distribution as contextual covariates. Including contextual variables increases the ability to characterize behavioral variability and empirically strengthens previous findings that deep-feeding blue whales respond significantly to mid-frequency sound exposure. However, our results are only based on a single behavioral state with a limited sample size, and this analytical framework should be applied broadly across behavioral states. The increased capability to describe and account for individual response variability by including environmental variables, such as prey, that drive foraging behavior underscores the importance of integrating these and other relevant contextual parameters in experimental designs. Our results suggest the need to measure and account for the ecological dynamics of predator-prey

  6. Prey-mediated behavioral responses of feeding blue whales in controlled sound exposure experiments.

    PubMed

    Friedlaender, A S; Hazen, E L; Goldbogen, J A; Stimpert, A K; Calambokidis, J; Southall, B L

    2016-06-01

    Behavioral response studies provide significant insights into the nature, magnitude, and consequences of changes in animal behavior in response to some external stimulus. Controlled exposure experiments (CEEs) to study behavioral response have faced challenges in quantifying the importance of and interaction among individual variability, exposure conditions, and environmental covariates. To investigate these complex parameters relative to blue whale behavior and how it may change as a function of certain sounds, we deployed multi-sensor acoustic tags and conducted CEEs using simulated mid-frequency active sonar (MFAS) and pseudo-random noise (PRN) stimuli, while collecting synoptic, quantitative prey measures. In contrast to previous approaches that lacked such prey data, our integrated approach explained substantially more variance in blue whale dive behavioral responses to mid-frequency sounds (r2 = 0.725 vs. 0.14 previously). Results demonstrate that deep-feeding whales respond more clearly and strongly to CEEs than those in other behavioral states, but this was only evident with the increased explanatory power provided by incorporating prey density and distribution as contextual covariates. Including contextual variables increases the ability to characterize behavioral variability and empirically strengthens previous findings that deep-feeding blue whales respond significantly to mid-frequency sound exposure. However, our results are only based on a single behavioral state with a limited sample size, and this analytical framework should be applied broadly across behavioral states. The increased capability to describe and account for individual response variability by including environmental variables, such as prey, that drive foraging behavior underscores the importance of integrating these and other relevant contextual parameters in experimental designs. Our results suggest the need to measure and account for the ecological dynamics of predator-prey

  7. Comparing visual prey detection among species of piscivorous salmonids: effects of light and low turbidities

    USGS Publications Warehouse

    Mazur, Michael M.; Beauchamp, David A.

    2003-01-01

    Differences in reaction distance to prey fish by piscivorous salmonids can alter predator–prey interactions under different visual conditions. We compared reaction distances of three piscivorous salmonids commonly found in western lakes: cutthroat trout, Oncorhynchus clarki utah, rainbow trout, O. mykiss, and the nonnative lake char, Salvelinus namaycush. Reaction distances to salmonid prey were measured as functions of light and turbidity in a controlled laboratory setting. In addition, predation rates and swimming speeds of lake char preying on juvenile cutthroat trout were measured experimentally under a range of light levels. Reaction distances for cutthroat trout and rainbow trout increased rapidly as light levels increased, reaching relatively constant reaction distances at higher light levels. Reaction distances for lake char were similar to cutthroat trout and rainbow trout at the lower light levels; however, lake char reaction distances continued to increase with increasing light intensity to asymptote at distances 65% higher than those for both cutthroat and rainbow trout. Predation rates by lake char were low for the darkest light levels, increased rapidly under low light levels (0.50–0.75 lx), and then declined to an intermediate rate at all higher light levels. Swimming speeds by lake char also increased rapidly from extremely low light conditions to a peak and declined to an intermediate level at light levels above 1.00 lx. These results suggest that, above the saturation intensity threshold, piscivorous lake char react to fish prey at greater distances than do cutthroat trout and rainbow trout. These differences may help explain the decline of native trout following the introductions of nonnative lake char in lakes and reservoirs of western North America.

  8. Top predators negate the effect of mesopredators on prey physiology.

    PubMed

    Palacios, Maria M; Killen, Shaun S; Nadler, Lauren E; White, James R; McCormick, Mark I

    2016-07-01

    Predation theory and empirical evidence suggest that top predators benefit the survival of resource prey through the suppression of mesopredators. However, whether such behavioural suppression can also affect the physiology of resource prey has yet to be examined. Using a three-tier reef fish food web and intermittent-flow respirometry, our study examined changes in the metabolic rate of resource prey exposed to combinations of mesopredator and top predator cues. Under experimental conditions, the mesopredator (dottyback, Pseudochromis fuscus) continuously foraged and attacked resource prey (juveniles of the damselfish Pomacentrus amboinensis) triggering an increase in prey O2 uptake by 38 ± 12·9% (mean ± SE). The visual stimulus of a top predator (coral trout, Plectropomus leopardus) restricted the foraging activity of the mesopredator, indirectly allowing resource prey to minimize stress and maintain routine O2 uptake. Although not as strong as the effect of the top predator, the sight of a large non-predator species (thicklip wrasse, Hemigymnus melapterus) also reduced the impact of the mesopredator on prey metabolic rate. We conclude that lower trophic-level species can benefit physiologically from the presence of top predators through the behavioural suppression that top predators impose on mesopredators. By minimizing the energy spent on mesopredator avoidance and the associated stress response to mesopredator attacks, prey may be able to invest more energy in foraging and growth, highlighting the importance of the indirect, non-consumptive effects of top predators in marine food webs. PMID:27113316

  9. Assassin bug uses aggressive mimicry to lure spider prey

    PubMed Central

    Wignall, Anne E.; Taylor, Phillip W.

    2011-01-01

    Assassin bugs (Stenolemus bituberus) hunt web-building spiders by invading the web and plucking the silk to generate vibrations that lure the resident spider into striking range. To test whether vibrations generated by bugs aggressively mimic the vibrations generated by insect prey, we compared the responses of spiders to bugs with how they responded to prey, courting male spiders and leaves falling into the web. We also analysed the associated vibrations. Similar spider orientation and approach behaviours were observed in response to vibrations from bugs and prey, whereas different behaviours were observed in response to vibrations from male spiders and leaves. Peak frequency and duration of vibrations generated by bugs were similar to those generated by prey and courting males. Further, vibrations from bugs had a temporal structure and amplitude that were similar to vibrations generated by leg and body movements of prey and distinctly different to vibrations from courting males or leaves, or prey beating their wings. To be an effective predator, bugs do not need to mimic the full range of prey vibrations. Instead bugs are general mimics of a subset of prey vibrations that fall within the range of vibrations classified by spiders as ‘prey’. PMID:20980305

  10. Energy and protein content of coyote prey in southeastern Idaho

    SciTech Connect

    MacCracken, J.G.; Hansen, R.M.

    1986-04-30

    Gross energy, digestible energy, crude protein, and digestible crude protein were estimated for two leporids and five rodents that were the primary prey of coyotes (Canis latrans) in southeastern Idaho. Digestible protein estimates differed (38%-54%) more than digestible energy (3.5-4.4 kcal), in the prey examined. 15 references, 1 table.

  11. Invasive prey indirectly increase predation on their native competitors.

    PubMed

    Castorani, Max C N; Hovel, Kevin A

    2015-07-01

    Ecological theory predicts that invasive prey can interact with native prey directly by competing for shared resources or indirectly by changing the abundance or behavior of shared native predators. However, both the study and management of invasive prey have historically overlooked indirect effects. In southern California estuaries, introduction of the Asian nest mussel Arcuatula senhousia has been linked to profound changes in native bivalve assemblages, but the mechanisms of these interactions remain unclear. We performed three field experiments to assess the mechanisms of competition between Arcuatula and native bivalves, and evaluated the potential for Arcuatula to indirectly mediate native predator-prey dynamics. We found that Arcuatula reduces the diversity, abundance, and size of native bivalve recruits by preemptively exploiting space in surface sediments. When paired with native shallow-dwelling clams (Chione undatella and Laevicardium substriatum), Arcuatula reduces adult survival through overgrowth competition. However, Arcuatula also attracts native predators, causing apparent competition by indirectly increasing predation of native clams, especially for poorly defended species. Therefore, invasive prey can indirectly increase predation rates on native competitors by changing the behavior of shared native predators, but the magnitude of apparent competition strongly depends on the vulnerability of natives to predation. Interestingly, our results indicate that the vulnerability of invasive prey to predation can greatly exacerbate impacts on their native competitors. Our findings suggest that consideration of both direct and indirect effects of invasive prey, as well as native predator-prey relationships, should lead to more effective invasive species management.

  12. Red fox prey demands and implications to prairie duck production

    USGS Publications Warehouse

    Sargeant, A.B.

    1978-01-01

    Experiments were conducted during spring and summer with 33 red foxes (Vulpes vulpes) to determine prey demands, feeding characteristics, and growth rates using natural foods. Pups began eating prey the 4th week after birth. Then, prey consumption averaged 1.38 and 1.90 kg/pup/week for weeks 5-8 and 9-12 of the denning season respectively, and 2.54 kg/pup/week for the postdenning period. Feeding by adults averaged 2.25 kg/adult/week. Free water was not needed by either pups or adults. About 90 percent of the prey offered to pups on simulated natural diets was consumed, remains varied with prey availability and prey type. Prey biomass required by a typical fox family was estimated at 18.5 kg/km2 for the 12-week denning season and 2.4 kg/km2/week for the postdenning period. Because of the large prey demands, ducks could represent a small part of the foxes' diet and yet be of consequence to the productivity of particular species. An example is provided for the mallard (Anas platyrhynchos).

  13. Prey bacteria shape the community structure of their predators.

    PubMed

    Chen, Huan; Athar, Rana; Zheng, Guili; Williams, Henry N

    2011-08-01

    Although predator-prey interactions among higher organisms have been studied extensively, only few examples are known for microbes other than protists and viruses. Among the bacteria, the most studied obligate predators are the Bdellovibrio and like organisms (BALOs) that prey on many other bacteria. In the macroscopical world, both predator and prey influence the population size of the other's community, and may have a role in selection. However, selective pressures among prey and predatory bacteria have been rarely investigated. In this study, Bacteriovorax, a predator within the group of BALOs, in environmental waters were fed two prey bacteria, Vibrio vulnificus and Vibrio parahaemolyticus. The two prey species yielded distinct Bacteriovorax populations, evidence that selective pressures shaped the predator community and diversity. The results of laboratory experiments confirmed the differential predation of Bacteriovorax phylotypes on the two bacteria species. Not only did Bacteriovorax Cluster IX exhibit the versatility to be the exclusive efficient predator on Vibrio vulnificus, thereby, behaving as a specialist, but was also able to prey with similar efficiency on Vibrio parahaemolyticus, indicative of a generalist. Therefore, we proposed a designation of versatilist for this predator. This initiative should provide a basis for further efforts to characterize the predatory patterns of bacterial predators. The results of this study have revealed impacts of the prey on Bacteriovorax predation and in structuring the predator community, and advanced understanding of predation behavior in the microbial world.

  14. Scenario analysis of Agro-Environment measure adoption for soil erosion protection in Sicilian vineyard (Italy)

    NASA Astrophysics Data System (ADS)

    Novara, Agata; Gristina, Luciano; Fantappiè, Maria; Costantini, Edoardo

    2014-05-01

    Most of the challenges in designing land use policies that address sustainability issues are inherent to the concept of Agro-Environmental Measures (AEM). Researchers, farmers and mainly policy makers need to evaluate the impact of new and existing policies for soil protection. In Europe, farmers commit themselves, for a minimum period of at least five years, to adopt environmentally-friendly farming techniques that undergone legal obligations. On the other hand, farmers receive payments that provide compensation for additional costs and income foregone resulting from applying those environmentally friendly farming practices in line with the stipulations of agri-environment contracts. In this context we prospect scenarios on soil erosion variations in a detailed case study after the application of Agro-Environmental Measures (AEM). The study area is located in the South part of Sicily. In a district area of 11,588 ha, 35.5 % is devoted to vineyard cultivation, 32.2 % is arable land and only 11.1 % cultivated to olive grow. 2416 ha are urbanized areas and other less important crops. A paired-site approach was chosen to study the difference in soil organic carbon stocks after AEM adoption, following criteria based on Conteh (1999) also applied in several research studies. For the purpose of comparison, the members of a paired site were selected to be similar with respect to the type of soil, slope, elevation, and drainage, but not to AEM. The comparisons were made between adjacent patches of land with different AEM, and a known history of land use and management. 100 paired sites (two adjacent plots) were chosen and three soil samples (0-30 cm depth) were collected in each plot (600 soil samples). The rainfall erosivity (R) factor (Mj mm ha-1 hour-1 year-1) was estimated with the formula specifically proposed for Sicily by Ferro and coauthors in 1999. The soil erodibility factor (K, in tons hour MJ-1 mm-1) was mapped on the base of soil texture and soil organic

  15. Piscivore-Prey Fish Interactions: Mechanisms behind Diurnal Patterns in Prey Selectivity in Brown and Clear Water

    PubMed Central

    Ranåker, Lynn; Persson, Jens; Jönsson, Mikael; Nilsson, P. Anders; Brönmark, Christer

    2014-01-01

    Environmental change may affect predator-prey interactions in lakes through deterioration of visual conditions affecting foraging success of visually oriented predators. Environmental change in lakes includes an increase in humic matter causing browner water and reduced visibility, affecting the behavioural performance of both piscivores and prey. We studied diurnal patterns of prey selection in piscivorous pikeperch (Sander lucioperca) in both field and laboratory investigations. In the field we estimated prey selectivity and prey availability during day and night in a clear and a brown water lake. Further, prey selectivity during day and night conditions was studied in the laboratory where we manipulated optical conditions (humic matter content) of the water. Here, we also studied the behaviours of piscivores and prey, focusing on foraging-cycle stages such as number of interests and attacks by the pikeperch as well as the escape distance of the prey fish species. Analyses of gut contents from the field study showed that pikeperch selected perch (Perca fluviatilis) over roach (Rutilus rutilus) prey in both lakes during the day, but changed selectivity towards roach in both lakes at night. These results were corroborated in the selectivity experiments along a brown-water gradient in day and night light conditions. However, a change in selectivity from perch to roach was observed when the optical condition was heavily degraded, from either brown-stained water or light intensity. At longer visual ranges, roach initiated escape at distances greater than pikeperch attack distances, whereas perch stayed inactive making pikeperch approach and attack at the closest range possible. Roach anti-predatory behaviour decreased in deteriorated visual conditions, altering selectivity patterns. Our results highlight the importance of investigating both predator and prey responses to visibility conditions in order to understand the effects of degrading optical conditions on

  16. Bioeconomic harvesting of a prey-predator fishery.

    PubMed

    Das, Tapasi; Mukherjee, R N; Chaudhuri, K S

    2009-09-01

    This paper deals with the problem of non-selective harvesting of a prey-predator system by using a reasonable catch-rate function instead of usual catch-per-unit-efforthypothesis. Here both the prey and the predator species obey the law of logistic growth. We have taken the predator functional response to prey density in such a form that each predator's functional response to the prey density approaches a constant as the prey population increases. Boundedness of the exploited system is examined. The existence of its steady states and their stability (local and global) are studied using Eigenvalue analysis. The existence of bionomic equilibria has been illustrated using a numerical example. The problem of determining the optimal harvesting policy is then solved by using Pontryagin's maximum principle. PMID:22880894

  17. A dedicated visual pathway for prey detection in larval zebrafish.

    PubMed

    Semmelhack, Julia L; Donovan, Joseph C; Thiele, Tod R; Kuehn, Enrico; Laurell, Eva; Baier, Herwig

    2014-01-01

    Zebrafish larvae show characteristic prey capture behavior in response to small moving objects. The neural mechanism used to recognize objects as prey remains largely unknown. We devised a machine learning behavior classification system to quantify hunting kinematics in semi-restrained animals exposed to a range of virtual stimuli. Two-photon calcium imaging revealed a small visual area, AF7, that was activated specifically by the optimal prey stimulus. This pretectal region is innervated by two types of retinal ganglion cells, which also send collaterals to the optic tectum. Laser ablation of AF7 markedly reduced prey capture behavior. We identified neurons with arbors in AF7 and found that they projected to multiple sensory and premotor areas: the optic tectum, the nucleus of the medial longitudinal fasciculus (nMLF) and the hindbrain. These findings indicate that computations in the retina give rise to a visual stream which transforms sensory information into a directed prey capture response. PMID:25490154

  18. Distinguishing the Impacts of Inadequate Prey and Vessel Traffic on an Endangered Killer Whale (Orcinus orca) Population

    PubMed Central

    Ayres, Katherine L.; Booth, Rebecca K.; Hempelmann, Jennifer A.; Koski, Kari L.; Emmons, Candice K.; Baird, Robin W.; Balcomb-Bartok, Kelley; Hanson, M. Bradley; Ford, Michael J.; Wasser, Samuel K.

    2012-01-01

    Managing endangered species often involves evaluating the relative impacts of multiple anthropogenic and ecological pressures. This challenge is particularly formidable for cetaceans, which spend the majority of their time underwater. Noninvasive physiological approaches can be especially informative in this regard. We used a combination of fecal thyroid (T3) and glucocorticoid (GC) hormone measures to assess two threats influencing the endangered southern resident killer whales (SRKW; Orcinus orca) that frequent the inland waters of British Columbia, Canada and Washington, U.S.A. Glucocorticoids increase in response to nutritional and psychological stress, whereas thyroid hormone declines in response to nutritional stress but is unaffected by psychological stress. The inadequate prey hypothesis argues that the killer whales have become prey limited due to reductions of their dominant prey, Chinook salmon (Oncorhynchus tshawytscha). The vessel impact hypothesis argues that high numbers of vessels in close proximity to the whales cause disturbance via psychological stress and/or impaired foraging ability. The GC and T3 measures supported the inadequate prey hypothesis. In particular, GC concentrations were negatively correlated with short-term changes in prey availability. Whereas, T3 concentrations varied by date and year in a manner that corresponded with more long-term prey availability. Physiological correlations with prey overshadowed any impacts of vessels since GCs were lowest during the peak in vessel abundance, which also coincided with the peak in salmon availability. Our results suggest that identification and recovery of strategic salmon populations in the SRKW diet are important to effectively promote SRKW recovery. PMID:22701560

  19. An investigation into the chemical composition of alternative invertebrate prey.

    PubMed

    Oonincx, D G A B; Dierenfeld, E S

    2012-01-01

    The aim of this study was to determine the chemical composition of eight invertebrate species and evaluate their suitability as alternative prey. The species selected were rusty red cockroaches (Blatta lateralis), six-spotted cockroaches (Eublaberus distanti), Madagascar hissing cockroaches (Gromphadorhina portentosa), fruit flies (Drosophila melanogaster), false katydids (Microcentrum rhombifolium), beetles of the mealworm (Tenebrio molitor), and superworm beetles (Zophobas morio), as well as woodlice (Porcellio scaber). Dry matter (DM), crude protein, crude fat, neutral detergent fiber, acid detergent fiber, ash, macro and trace minerals, vitamins A and E, and carotenoid concentrations were quantified. Significant differences were found between species. Crude protein content ranged from 38 to 76% DM, fat from14 to 54% DM, and ash from 2 to 8% DM. In most species, calcium:phosphorus was low (0.08-0.30:1); however, P. scaber was an exception (12:1) and might prove useful as a dietary source of calcium for insectivores. Vitamin E content was low for most species (6-16 mg/kg DM), except for D. melanogaster and M. rhombifolium (112 and 110 mg/kg DM). The retinol content, as a measure of vitamin A activity, was low in all specimens, but varied greatly among samples (0.670-886 mg/kg DM). The data presented can be used to alter diets to better suit the estimated requirements of insectivores in captivity. Future research on the topic of composition of invertebrate prey species should focus on determination of nutrient differences owing to species, developmental stage, and diet.

  20. Acoustic behaviour of echolocating porpoises during prey capture.

    PubMed

    Deruiter, Stacy L; Bahr, Alexander; Blanchet, Marie-Anne; Hansen, Sabina Fobian; Kristensen, Jakob Højer; Madsen, Peter T; Tyack, Peter L; Wahlberg, Magnus

    2009-10-01

    Porpoise echolocation has been studied previously, mainly in target detection experiments using stationed animals and steel sphere targets, but little is known about the acoustic behaviour of free-swimming porpoises echolocating for prey. Here, we used small onboard sound and orientation recording tags to study the echolocation behaviour of free-swimming trained porpoises as they caught dead, freely drifting fish. We analysed porpoise echolocation behaviour leading up to and following prey capture events, including variability in echolocation in response to vision restriction, prey species, and individual porpoise tested. The porpoises produced echolocation clicks as they searched for the fish, followed by fast-repetition-rate clicks (echolocation buzzes) when acquiring prey. During buzzes, which usually began when porpoises were about 1-2 body lengths from prey, tag-recorded click levels decreased by about 10 dB, click rates increased to over 300 clicks per second, and variability in body orientation (roll) increased. Buzzes generally continued beyond the first contact with the fish, and often extended until or after the end of prey handling. This unexplained continuation of buzzes after prey capture raises questions about the function of buzzes, suggesting that in addition to providing detailed information on target location during the capture, they may serve additional purposes such as the relocation of potentially escaping prey. We conclude that porpoises display the same overall acoustic prey capture behaviour seen in larger toothed whales in the wild, albeit at a faster pace, clicking slowly during search and approach phases and buzzing during prey capture.

  1. Early Cretaceous spider web with its prey.

    PubMed

    Peñalver, Enrique; Grimaldi, David A; Delclòs, Xavier

    2006-06-23

    The orb web is a spectacular evolutionary innovation that enables spiders to catch flying prey. This elegant, geometric structure is woven with silk fibers that are renowned for their superior mechanical properties. We used silk gland expression libraries to address a long-standing controversy concerning the evolution of the orb-web architecture. Contrary to the view that the orb-web design evolved multiple times, we found that the distribution and phylogeny of silk proteins support a single, ancient origin of the orb web at least 136 million years ago. Furthermore, we substantially expanded the repository of silk sequences that can be used for the synthesis of high-performance biomaterials. PMID:16794072

  2. Chemical Prey Luring in Jackson's Chameleons.

    PubMed

    Preest, Marion R; Ward, Matthew J; Poon, Thomas; Hermanson, John W

    2016-01-01

    Lizards in the family Chamaeleonidae have been described as wiping a viscous substance from a pouch (the temporal pouch) at the angle of the jaw on branches and then capturing flies that land near the area where the wiping occurs. We confirmed the presence of this pouch in Jackson's chameleons. Histological work suggested that the material contained within is a result of decomposition of food and sloughed skin that has been trapped in the pouch rather than a glandular secretion. Gas chromatography-mass spectrometry indicated the presence of compounds that are both volatile and odiferous and similar to insect pheromones. Choice tests with houseflies revealed attraction to the temporal pouch material. Some authors have speculated that the temporal pouch material serves a function in territory marking and/or predator deterrence. While it may play these roles, our results suggest that it also plays a role in chemical luring of prey. PMID:27082721

  3. Degraded Environments Alter Prey Risk Assessment

    PubMed Central

    Lönnstedt, Oona M; McCormick, Mark I; Chivers, Douglas P

    2013-01-01

    Elevated water temperatures, a decrease in ocean pH, and an increasing prevalence of severe storms have lead to bleaching and death of the hard corals that underpin coral reef ecosystems. As coral cover declines, fish diversity and abundance declines. How degradation of coral reefs affects behavior of reef inhabitants is unknown. Here, we demonstrate that risk assessment behaviors of prey are severely affected by coral degradation. Juvenile damselfish were exposed to visual and olfactory indicators of predation risk in healthy live, thermally bleached, and dead coral in a series of laboratory and field experiments. While fish still responded to visual cues in all habitats, they did not respond to olfactory indicators of risk in dead coral habitats, likely as a result of alteration or degradation of chemical cues. These cues are critical for learning and avoiding predators, and a failure to respond can have dramatic repercussions for survival and recruitment. PMID:23403754

  4. Stability and Hopf bifurcation for a prey-predator model with prey-stage structure and diffusion.

    PubMed

    Wang, Mingxin

    2008-04-01

    In this paper, we first propose a prey-predator model with prey-stage structure and diffusion. Then we discuss the following three problems: (1) stability of non-negative constant steady states for the reduced ODE system and the corresponding reaction diffusion system with homogeneous Neumann boundary conditions; (2) Hopf bifurcation for the ODE system; (3) Hopf bifurcation created by diffusion.

  5. Prey risk allocation in a grazing ecosystem.

    PubMed

    Gude, Justin A; Garrott, Robert A; Borkowski, John J; King, Fred

    2006-02-01

    Understanding the behaviorally mediated indirect effects of predators in ecosystems requires knowledge of predator-prey behavioral interactions. In predator-ungulate-plant systems, empirical research quantifying how predators affect ungulate group sizes and distribution, in the context of other influential variables, is particularly needed. The risk allocation hypothesis proposes that prey behavioral responses to predation risk depend on background frequencies of exposure to risk, and it can be used to make predictions about predator-ungulate-plant interactions. We determined non-predation variables that affect elk (Cervus elaphus) group sizes and distribution on a winter range in the Greater Yellowstone Ecosystem (GYE) using logistic and log-linear regression on surveys of 513 1-km2 areas conducted over two years. Employing model selection techniques, we evaluated risk allocation and other a priori hypotheses of elk group size and distributional responses to wolf (Canis lupus) predation risk while accounting for influential non-wolf-predation variables. We found little evidence that wolves affect elk group sizes, which were strongly influenced by habitat type and hunting by humans. Following predictions from the risk allocation hypothesis, wolves likely created a more dynamic elk distribution in areas that they frequently hunted, as elk tended to move following wolf encounters in those areas. This response should dilute elk foraging pressure on plant communities in areas where they are frequently hunted by wolves. We predict that this should decrease the spatial heterogeneity of elk impacts on grasslands in areas that wolves frequently hunt. We also predict that this should decrease browsing pressure on heavily browsed woody plant stands in certain areas, which is supported by recent research in the GYE. PMID:16705980

  6. Wave propagation in predator-prey systems

    NASA Astrophysics Data System (ADS)

    Fu, Sheng-Chen; Tsai, Je-Chiang

    2015-12-01

    In this paper, we study a class of predator-prey systems of reaction-diffusion type. Specifically, we are interested in the dynamical behaviour for the solution with the initial distribution where the prey species is at the level of the carrying capacity, and the density of the predator species has compact support, or exponentially small tails near x=+/- ∞ . Numerical evidence suggests that this will lead to the formation of a pair of diverging waves propagating outwards from the initial zone. Motivated by this phenomenon, we establish the existence of a family of travelling waves with the minimum speed. Unlike the previous studies, we do not use the shooting argument to show this. Instead, we apply an iteration process based on Berestycki et al 2005 (Math Comput. Modelling 50 1385-93) to construct a set of super/sub-solutions. Since the underlying system does not enjoy the comparison principle, such a set of super/sub-solutions is not based on travelling waves, and in fact the super/sub-solutions depend on each other. With the aid of the set of super/sub-solutions, we can construct the solution of the truncated problem on the finite interval, which, via the limiting argument, can in turn generate the wave solution. There are several advantages to this approach. First, it can remove the technical assumptions on the diffusivities of the species in the existing literature. Second, this approach is of PDE type, and hence it can shed some light on the spreading phenomenon indicated by numerical simulation. In fact, we can compute the spreading speed of the predator species for a class of biologically acceptable initial distributions. Third, this approach might be applied to the study of waves in non-cooperative systems (i.e. a system without a comparison principle).

  7. Modelling the Effects of Prey Size and Distribution on Prey Capture Rates of Two Sympatric Marine Predators

    PubMed Central

    Thaxter, Chris B.; Daunt, Francis; Grémillet, David; Harris, Mike P.; Benvenuti, Silvano; Watanuki, Yutaka; Hamer, Keith C.; Wanless, Sarah

    2013-01-01

    Understanding how prey capture rates are influenced by feeding ecology and environmental conditions is fundamental to assessing anthropogenic impacts on marine higher predators. We compared how prey capture rates varied in relation to prey size, prey patch distribution and prey density for two species of alcid, common guillemot (Uria aalge) and razorbill (Alca torda) during the chick-rearing period. We developed a Monte Carlo approach parameterised with foraging behaviour from bird-borne data loggers, observations of prey fed to chicks, and adult diet from water-offloading, to construct a bio-energetics model. Our primary goal was to estimate prey capture rates, and a secondary aim was to test responses to a set of biologically plausible environmental scenarios. Estimated prey capture rates were 1.5±0.8 items per dive (0.8±0.4 and 1.1±0.6 items per minute foraging and underwater, respectively) for guillemots and 3.7±2.4 items per dive (4.9±3.1 and 7.3±4.0 items per minute foraging and underwater, respectively) for razorbills. Based on species' ecology, diet and flight costs, we predicted that razorbills would be more sensitive to decreases in 0-group sandeel (Ammodytes marinus) length (prediction 1), but guillemots would be more sensitive to prey patches that were more widely spaced (prediction 2), and lower in prey density (prediction 3). Estimated prey capture rates increased non-linearly as 0-group sandeel length declined, with the slope being steeper in razorbills, supporting prediction 1. When prey patches were more dispersed, estimated daily energy expenditure increased by a factor of 3.0 for guillemots and 2.3 for razorbills, suggesting guillemots were more sensitive to patchier prey, supporting prediction 2. However, both species responded similarly to reduced prey density (guillemot expenditure increased by 1.7; razorbill by 1.6), thus not supporting prediction 3. This bio-energetics approach complements other foraging models in predicting likely

  8. Modelling the effects of prey size and distribution on prey capture rates of two sympatric marine predators.

    PubMed

    Thaxter, Chris B; Daunt, Francis; Grémillet, David; Harris, Mike P; Benvenuti, Silvano; Watanuki, Yutaka; Hamer, Keith C; Wanless, Sarah

    2013-01-01

    Understanding how prey capture rates are influenced by feeding ecology and environmental conditions is fundamental to assessing anthropogenic impacts on marine higher predators. We compared how prey capture rates varied in relation to prey size, prey patch distribution and prey density for two species of alcid, common guillemot (Uria aalge) and razorbill (Alca torda) during the chick-rearing period. We developed a Monte Carlo approach parameterised with foraging behaviour from bird-borne data loggers, observations of prey fed to chicks, and adult diet from water-offloading, to construct a bio-energetics model. Our primary goal was to estimate prey capture rates, and a secondary aim was to test responses to a set of biologically plausible environmental scenarios. Estimated prey capture rates were 1.5 ± 0.8 items per dive (0.8 ± 0.4 and 1.1 ± 0.6 items per minute foraging and underwater, respectively) for guillemots and 3.7 ± 2.4 items per dive (4.9 ± 3.1 and 7.3 ± 4.0 items per minute foraging and underwater, respectively) for razorbills. Based on species' ecology, diet and flight costs, we predicted that razorbills would be more sensitive to decreases in 0-group sandeel (Ammodytes marinus) length (prediction 1), but guillemots would be more sensitive to prey patches that were more widely spaced (prediction 2), and lower in prey density (prediction 3). Estimated prey capture rates increased non-linearly as 0-group sandeel length declined, with the slope being steeper in razorbills, supporting prediction 1. When prey patches were more dispersed, estimated daily energy expenditure increased by a factor of 3.0 for guillemots and 2.3 for razorbills, suggesting guillemots were more sensitive to patchier prey, supporting prediction 2. However, both species responded similarly to reduced prey density (guillemot expenditure increased by 1.7; razorbill by 1.6), thus not supporting prediction 3. This bio-energetics approach complements other foraging models in

  9. Measuring the Effectiveness of Routine Child Protection Services: The Results from an Evidence Based Strategy

    ERIC Educational Resources Information Center

    O'Brien, Michael

    2011-01-01

    Most of what is known about the effectiveness of child welfare is found in studies of specific programs. Little is known about the effectiveness of the routine services provided in child protection systems. Family and Children's Services of Renfrew County is a Canadian child welfare agency that decided to expand its mission beyond protecting…

  10. MEASURING HYDROLOGICAL CHANGE DURING EXURBAN DEVELOPMENT: COLLABORATIVE HYDROLOGIC RESEARCH IN THE CLARKSBURG SPECIAL PROTECTION AREA

    EPA Science Inventory

    This research project is focused on the Clarksburg Special Protection Area (CSPA) in Montgomery County, Maryland. The CSPA subwatersheds are on the outer edge of the exurban development shockwave expanding outward from the Washington, DC, metropolitan area. The CSPA is an area o...

  11. MEASURING HYDROLOGICAL CHANGE DURING EXURBAN DEVELOPMENT: COLLABORATIVE HYDROLOGIC RESEARCH IN THE CLARKSBURG SPECIAL PROTECTION AREA

    EPA Science Inventory

    This research project is focused on the Clarksburg Special Protection Area (CSPA) in Montgomery County, Maryland. The CSPA subwatersheds are on the outer edge of the exurban development shockwave expanding outward from the Washington DC metropolitan area. The CSPA is an area of ...

  12. Measurement of sunscreen immune protection factors in humans: a consensus paper.

    PubMed

    Fourtanier, Anny; Moyal, Dominique; Maccario, Jean; Compan, Delphine; Wolf, Peter; Quehenberger, Franz; Cooper, Kevin; Baron, Elma; Halliday, Gary; Poon, Terrence; Seed, Paul; Walker, Susan L; Young, Antony R

    2005-09-01

    It is increasingly accepted that sunscreens should protect against ultraviolet radiation (UVR)-induced immunosuppression, with an index of protection that can be compared with the sun protection factor (SPF). Five groups of immunoprotection researchers met to discuss the status of immune protection factor (IPF) evaluation in human skin in vivo. Current methods rely on a suncreen's inhibition of UVR-induced local suppression of the contact hypersensitivity (CHS) response or the delayed-type hypersensitivity (DTH) response, using either the induction or the elicitation arms of these responses. The induction arm of the CHS response has the advantage of being sensitive to a single sub-erythemal exposure of solar-simulating radiation (SSR) that allows a direct comparison with the SPF. This approach, which necessitates sensitization, requires a large number of volunteers and is too labor intensive and time consuming to become a routine method. The elicitation arm of the CHS or DTH responses exploits prior sensitization to contact or recall antigens and has the advantage of being possible to apply on small groups of volunteers. Some current protocols, however, require repeat SSR exposures, which invalidates a direct comparison with SPF that is based on a single exposure. There is a need for a new simpler method of IPF that will have to be validated against existing models. PMID:16117779

  13. A differential line protection scheme for power systems based on composite voltage and current measurements

    SciTech Connect

    Aggarwal, R.K.; Johns, A.T.

    1989-07-01

    A differential feeder protection scheme that utilizes voltage and current signals is described. This approach obviates the need for relay bias to compensate for capacitance spill current, thus improving the relay sensitivity. From a practical point of view, the scheme has been designed to simplify the digital hardware requirements and reduce the bandwidth requirements for signal transmission over a fibre optic link.

  14. 49 CFR Appendix D to Part 192 - Criteria for Cathodic Protection and Determination of Measurements

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... material or structure may be used in place of the saturated copper-copper sulfate half cell if its... I. Criteria for cathodic protection— A. Steel, cast iron, and ductile iron structures. (1) A... cell. Determination of this voltage must be made with the protective current applied, and in...

  15. 49 CFR Appendix D to Part 192 - Criteria for Cathodic Protection and Determination of Measurements

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... material or structure may be used in place of the saturated copper-copper sulfate half cell if its... I. Criteria for cathodic protection— A. Steel, cast iron, and ductile iron structures. (1) A... cell. Determination of this voltage must be made with the protective current applied, and in...

  16. The packaging problem: bivalve prey selection and prey entry techniques of the octopus Enteroctopus dofleini.

    PubMed

    Anderson, Roland C; Mather, Jennifer A

    2007-08-01

    Many predators face a complex step of prey preparation before consumption. Octopuses faced with bivalve prey use several techniques to penetrate the shells to gain access to the meat inside. When given prey of mussels Mytilus trossulus, Manila clams Venerupis philippinarum, and littleneck clams Protothaca staminea, Enteroctopus dofleini solved the problem differently. They pulled apart V. philippinarum and M. trossulus, which had the thinnest shells and the least pulling resistance. P. staminea were eaten after the shells had been chipped or had been penetrated by drilling, presumably to inject a toxin. Likely because of these differences, octopuses consumed more V. philippinarum and M. trossulus than P. staminea when the mollusks were given to them either 1 species at a time or all together. However, when the shells were separated and the penetration problem removed, the octopuses predominantly chose P. staminea and nearly ignored M. trossulus. When V. philippinarum were wired shut, octopuses switched techniques. These results emphasize that octopuses can learn on the basis of nonvisual information and monitor their body position to carry out feeding actions.

  17. The packaging problem: bivalve prey selection and prey entry techniques of the octopus Enteroctopus dofleini.

    PubMed

    Anderson, Roland C; Mather, Jennifer A

    2007-08-01

    Many predators face a complex step of prey preparation before consumption. Octopuses faced with bivalve prey use several techniques to penetrate the shells to gain access to the meat inside. When given prey of mussels Mytilus trossulus, Manila clams Venerupis philippinarum, and littleneck clams Protothaca staminea, Enteroctopus dofleini solved the problem differently. They pulled apart V. philippinarum and M. trossulus, which had the thinnest shells and the least pulling resistance. P. staminea were eaten after the shells had been chipped or had been penetrated by drilling, presumably to inject a toxin. Likely because of these differences, octopuses consumed more V. philippinarum and M. trossulus than P. staminea when the mollusks were given to them either 1 species at a time or all together. However, when the shells were separated and the penetration problem removed, the octopuses predominantly chose P. staminea and nearly ignored M. trossulus. When V. philippinarum were wired shut, octopuses switched techniques. These results emphasize that octopuses can learn on the basis of nonvisual information and monitor their body position to carry out feeding actions. PMID:17696656

  18. Analysis of Prey-Predator Three Species Fishery Model with Harvesting Including Prey Refuge and Migration

    NASA Astrophysics Data System (ADS)

    Roy, Sankar Kumar; Roy, Banani

    In this article, a prey-predator system with Holling type II functional response for the predator population including prey refuge region has been analyzed. Also a harvesting effort has been considered for the predator population. The density-dependent mortality rate for the prey, predator and super predator has been considered. The equilibria of the proposed system have been determined. Local and global stabilities for the system have been discussed. We have used the analytic approach to derive the global asymptotic stabilities of the system. The maximal predator per capita consumption rate has been considered as a bifurcation parameter to evaluate Hopf bifurcation in the neighborhood of interior equilibrium point. Also, we have used fishing effort to harvest predator population of the system as a control to develop a dynamic framework to investigate the optimal utilization of the resource, sustainability properties of the stock and the resource rent is earned from the resource. Finally, we have presented some numerical simulations to verify the analytic results and the system has been analyzed through graphical illustrations.

  19. Aquatic prey capture in ray-finned fishes: a century of progress and new directions.

    PubMed

    Ferry-Graham, L A; Lauder, G V

    2001-05-01

    The head of ray-finned fishes is structurally complex and is composed of numerous bony, muscular, and ligamentous elements capable of intricate movement. Nearly two centuries of research have been devoted to understanding the function of this cranial musculoskeletal system during prey capture in the dense and viscous aquatic medium. Most fishes generate some amount of inertial suction to capture prey in water. In this overview we trace the history of functional morphological analyses of suction feeding in ray-finned fishes, with a particular focus on the mechanisms by which suction is generated, and present new data using a novel flow imaging technique that enables quantification of the water flow field into the mouth. We begin with a brief overview of studies of cranial anatomy and then summarize progress on understanding function as new information was brought to light by the application of various forms of technology, including high-speed cinematography and video, pressure, impedance, and bone strain measurement. We also provide data from a new technique, digital particle image velocimetry (DPIV) that allows us to quantify patterns of flow into the mouth. We believe that there are three general areas in which future progress needs to occur. First, quantitative three-dimensional studies of buccal and opercular cavity dimensions during prey capture are needed; sonomicrometry and endoscopy are techniques likely to yield these data. Second, a thorough quantitative analysis of the flow field into the mouth during prey capture is necessary to understand the effect of head movement on water in the vicinity of the prey; three-dimensional DPIV analyses will help to provide these data. Third, a more precise understanding of the fitness effects of structural and functional variables in the head coupled with rigorous statistical analyses will allow us to better understand the evolutionary consequences of intra- and interspecific variation in cranial morphology and function

  20. The predatory behavior of wintering Accipiter hawks: temporal patterns in activity of predators and prey.

    PubMed

    Roth, Timothy C; Lima, Steven L

    2007-05-01

    Studies focused on how prey trade-off predation and starvation risk are prevalent in behavioral ecology. However, our current understanding of these trade-offs is limited in one key respect: we know little about the behavior of predators. In this study, we provide some of the first detailed information on temporal patterns in the daily hunting behavior of bird-eating Accipiter hawks and relate that to their prey. During the winters of 1999-2004, twenty-one sharp-shinned hawks (A. striatus) and ten Cooper's hawks (A. cooperii) were intensively radio tracked in rural and urban habitats in western Indiana, USA. Cooper's hawks left roost before sunrise and usually returned to roost around sunset, while sharp-shinned hawks left roost at sunrise or later and returned to roost well before sunset. An overall measure of Cooper's-hawk-induced risk (a composite variable of attack rate and activity patterns) generally reflected the timing of prey activity, with peaks occurring around sunrise and sunset. In contrast, risk induced by the smaller sharp-shinned hawk did not strongly reflect the activity of their prey. Specifically, an early morning peak in prey activity did not correspond to a period with intense hawk activity. The lack of early morning hunting by sharp-shinned hawks may reflect the high risk of owl-induced predation experienced by these hawks. The net effect of this intraguild predation may be to "free" small birds from much hawk-induced predation risk prior to sunrise. This realization presents an alternative to energetics as an explanation for the early morning peak in small bird activity during the winter.

  1. PCB accumulation in Hudson River pumpkinseed sunfish and bullhead: Influences of invertebrate prey

    SciTech Connect

    Feldman, R.S.

    1992-01-01

    Hudson River sediments are contaminated with PCBs, and these toxic compounds are also in the water and have accumulated in food chains. The relative importance of exposure by fish to contaminated water vs. contaminated prey was unknown. further, is was not known if difference in diet could influence fish PCB levels. Invertebrates and fish were sampled in different habitats to address these issues. Invertebrate communities differed in several ecological measures between two different plant beds, and among experimentally manipulated habitats in one plant bed. Communities often differed significantly in parameters such as total invertebrate density, densities of individual taxa, taxonomic richness and similarity, and size distributions; some taxa were also absent from one habitat but present in another. Total PCBs differed significantly for invertebrate communities between the two plant beds (9.4 vs. 31.4 [mu]g/g), and between some of the communities in the manipulated habitats (1.8 vs 5.3 [mu]g/g). These differences did not translate into difference in PCBs among fish that fed in the different habitats. However, bullhead had significantly higher levels than pumpkinseed (15.4 vs. 6.9 [mu]g/g). Yearling pumpkinseed that fed on Hudson River invertebrates had 5x the PCB levels of pumpkinseed exposed for the same period to the water but not to the prey, and 18x as much PCBs as fish unexposed to either Hudson River water or prey. Further, fish that fed on local prey had a higher proportion of high-Cl isomers than those exposed only to the contaminated water. Fish that fed in different habitats did not have different PCB levels. Thus, the role of diet needs further experimentation, but it is clear that local prey are the major route for PCB accumulation in yearling pumpkinseed.

  2. The predatory behavior of wintering Accipiter hawks: temporal patterns in activity of predators and prey.

    PubMed

    Roth, Timothy C; Lima, Steven L

    2007-05-01

    Studies focused on how prey trade-off predation and starvation risk are prevalent in behavioral ecology. However, our current understanding of these trade-offs is limited in one key respect: we know little about the behavior of predators. In this study, we provide some of the first detailed information on temporal patterns in the daily hunting behavior of bird-eating Accipiter hawks and relate that to their prey. During the winters of 1999-2004, twenty-one sharp-shinned hawks (A. striatus) and ten Cooper's hawks (A. cooperii) were intensively radio tracked in rural and urban habitats in western Indiana, USA. Cooper's hawks left roost before sunrise and usually returned to roost around sunset, while sharp-shinned hawks left roost at sunrise or later and returned to roost well before sunset. An overall measure of Cooper's-hawk-induced risk (a composite variable of attack rate and activity patterns) generally reflected the timing of prey activity, with peaks occurring around sunrise and sunset. In contrast, risk induced by the smaller sharp-shinned hawk did not strongly reflect the activity of their prey. Specifically, an early morning peak in prey activity did not correspond to a period with intense hawk activity. The lack of early morning hunting by sharp-shinned hawks may reflect the high risk of owl-induced predation experienced by these hawks. The net effect of this intraguild predation may be to "free" small birds from much hawk-induced predation risk prior to sunrise. This realization presents an alternative to energetics as an explanation for the early morning peak in small bird activity during the winter. PMID:17216210

  3. An island-wide predator manipulation reveals immediate and long-lasting matching of risk by prey

    PubMed Central

    Orrock, John L.; Fletcher, Robert J.

    2014-01-01

    Anti-predator behaviour affects prey population dynamics, mediates cascading effects in food webs and influences the likelihood of rapid extinctions. Predator manipulations in natural settings provide a rare opportunity to understand how prey anti-predator behaviour is affected by large-scale changes in predators. Here, we couple a long-term, island-wide manipulation of an important rodent predator, the island fox (Urocyon littoralis), with nearly 6 years of measurements on foraging by deer mice (Peromyscus maniculatus) to provide unequivocal evidence that prey closely match their foraging behaviour to the number of fox predators present on the island. Peromyscus maniculatus foraging among exposed and sheltered microhabitats (a measure of aversion to predation risk) closely tracked fox density, but the nature of this effect depended upon nightly environmental conditions known to affect rodent susceptibility to predators. These effects could not be explained by changes in density of deer mice over time. Our work reveals that prey in natural settings are cognizant of the dynamic nature of their predators over timescales that span many years, and that predator removals spanning many generations of prey do not result in a loss of anti-predator behaviour. PMID:24759863

  4. An island-wide predator manipulation reveals immediate and long-lasting matching of risk by prey.

    PubMed

    Orrock, John L; Fletcher, Robert J

    2014-06-01

    Anti-predator behaviour affects prey population dynamics, mediates cascading effects in food webs and influences the likelihood of rapid extinctions. Predator manipulations in natural settings provide a rare opportunity to understand how prey anti-predator behaviour is affected by large-scale changes in predators. Here, we couple a long-term, island-wide manipulation of an important rodent predator, the island fox (Urocyon littoralis), with nearly 6 years of measurements on foraging by deer mice (Peromyscus maniculatus) to provide unequivocal evidence that prey closely match their foraging behaviour to the number of fox predators present on the island. Peromyscus maniculatus foraging among exposed and sheltered microhabitats (a measure of aversion to predation risk) closely tracked fox density, but the nature of this effect depended upon nightly environmental conditions known to affect rodent susceptibility to predators. These effects could not be explained by changes in density of deer mice over time. Our work reveals that prey in natural settings are cognizant of the dynamic nature of their predators over timescales that span many years, and that predator removals spanning many generations of prey do not result in a loss of anti-predator behaviour.

  5. Feeding Activity, Rate of Consumption, Daily Ration and Prey Selection of Major Predators in John Day Reservoir, 1984 : Annual Report.

    SciTech Connect

    Gray, Gerard A.; United States. Bonneville Power Administration; U.S. Fish and Wildlife Service; National Fishery Research Center

    1986-07-01

    The extent of predation on juvenile salmonids in John Day Reservoir was determined. Salmonids were the single most important food item by weight for northern squawfish (Ptychocheilus oregonensis) in the restricted zones at McNary tailrace and John Day forebay during all sampling periods. Salmonids accounted for 18.1% of the weight in the diet of walleyes (Stizostedion vitreum vitreum) in 1984 which was at least twice that found in previous years. In smallmouth bass (Micropterus dolomieui) salmonids contributed little to their diet whereas for channel catfish (Ictalurus punctatus) fish accounted for 64.1% of the weight in their diet with salmonids responsible for approximately half of this weight. An intensive search of the fisheries literature was conducted to review various fish capture and control techniques which might have potential as predation control measures for the major predators of juvenile salmonids in the Columbia River system. Most prey protection measures were judged to have high potential and direct predator control measures were judged to have moderate or low potential.

  6. Predicting Intention to Take Protective Measures During Haze: The Roles of Efficacy, Threat, Media Trust, and Affective Attitude.

    PubMed

    Lin, Trisha T C; Bautista, John Robert

    2016-07-01

    The annual Southeast Asian haze pollution raises public health concerns in this region. Based on a modified extended parallel process model, this study examines efficacy (self-efficacy and response efficacy) and perceived threat (susceptibility and severity) and incorporates new constructs of media trust and affective attitude. Results from a Web survey of 410 undergraduate students in Singapore show that response efficacy to seek haze-related information mediates the association between perceived self-efficacy and intention to take protective measures during haze. Moreover, self-efficacy is negatively associated with affective attitude (e.g., fear and worry) toward haze-related health problems. Next, perceived severity and perceived susceptibility are positively associated with response efficacy and affective attitude. Affective attitude toward haze is a stronger predictor than response efficacy for behavioral intention. Finally, trust in new media is positively associated with young Singaporeans' affective attitude, which positively affects their behavioral intention to take protective measures.

  7. The common house spider alters the material and mechanical properties of cobweb silk in response to different prey.

    PubMed

    Boutry, Cecilia; Blackledge, Todd A

    2008-11-01

    Many spiders depend upon webs to capture prey. Web function results from architecture and mechanical performance of the silk. We hypothesized that the common house spider, Achaearanea tepidariorum, would alter the mechanical performance of its cobweb in response to different prey by varying the structural and material properties of its silk. We fed spiders either large, high kinetic energy crickets or small, low kinetic energy pillbugs for 1 week and then examined their freshly spun silk. We separated mechanical performance into structural and material effects. We measured both types of properties for silk threads collected directly from cobwebs to test for "tuning" of silk performance to different aspects of prey capture. We compared silk from two different functional regions of the cobweb-sticky gumfooted threads that adhere directly to prey and supporting threads that maintain web integrity. Supporting threads from cricket-fed spiders were stiffer and tougher than supporting threads from pillbug-fed spiders. Both types of silk from cricket-fed spiders broke at higher loads than silk from pillbug-fed spiders. We explain this variation using a simple model of forces exerted by prey and spiders on single threads and propose potential mechanisms for this change in material properties. Two alternative, nonexclusive, hypotheses are suggested by our data. Spiders may tune silk to different types of prey by spinning threads that are able to hold prey without deforming permanently. Alternatively, as spider's body mass differed dramatically between the two feeding regimes, spiders may tune silk to their own body mass. PMID:18651614

  8. The Effect of Digestive Capacity on the Intake Rate of Toxic and Non-Toxic Prey in an Ecological Context

    PubMed Central

    Oudman, Thomas; Hin, Vincent; Dekinga, Anne; van Gils, Jan A.

    2015-01-01

    Digestive capacity often limits food intake rate in animals. Many species can flexibly adjust digestive organ mass, enabling them to increase intake rate in times of increased energy requirement and/or scarcity of high-quality prey. However, some prey species are defended by secondary compounds, thereby forcing a toxin limitation on the forager’s intake rate, a constraint that potentially cannot be alleviated by enlarging digestive capacity. Hence, physiological flexibility may have a differential effect on intake of different prey types, and consequently on dietary preferences. We tested this effect in red knots (Calidris canutus canutus), medium-sized migratory shorebirds that feed on hard-shelled, usually mollusc, prey. Because they ingest their prey whole and crush the shell in their gizzard, the intake rate of red knots is generally constrained by digestive capacity. However, one of their main prey, the bivalve Loripes lucinalis, imposes a toxin constraint due to its symbiosis with sulphide-oxidizing bacteria. We manipulated gizzard sizes of red knots through prolonged exposure to hard-shelled or soft foods. We then measured maximum intake rates of toxic Loripes versus a non-toxic bivalve, Dosinia isocardia. We found that intake of Dosinia exponentially increased with gizzard mass, confirming earlier results with non-toxic prey, whereas intake of Loripes was independent of gizzard mass. Using linear programming, we show that this leads to markedly different expected diet preferences in red knots that try to maximize energy intake rate with a small versus a large gizzard. Intra- and inter-individual variation in digestive capacity is found in many animal species. Hence, the here proposed functional link with individual differences in foraging decisions may be general. We emphasize the potential relevance of individual variation in physiology when studying trophic interactions. PMID:26287951

  9. Invading rainbow trout usurp a terrestrial prey subsidy from native charr and reduce their growth and abundance.

    PubMed

    Baxter, Colden V; Fausch, Kurt D; Murakami, Masashi; Chapman, Phillip L

    2007-08-01

    Movements of prey organisms across ecosystem boundaries often subsidize consumer populations in adjacent habitats. Human disturbances such as habitat degradation or non-native species invasions may alter the characteristics or fate of these prey subsidies, but few studies have measured the direct effects of this disruption on the growth and local abundance of predators in recipient habitats. Here we present evidence, obtained from a combined experimental and comparative study in northern Japan, that an invading stream fish usurped the flux of allochthonous prey to a native fish, consequently altering the diet and reducing the growth and abundance of the native species. A large-scale field experiment showed that excluding terrestrial invertebrates that fell into the stream with a mesh greenhouse reduced terrestrial prey in diets of native Dolly Varden charr (Salvelinus malma) by 46-70%, and reduced their growth by 25% over six weeks. However, when nonnative rainbow trout (Oncorhynchus mykiss) were introduced, they monopolized these prey and caused an even greater reduction of terrestrial prey in charr diets of 82-93%, and reduced charr growth by 31% over the same period. Adding both greenhouse and rainbow trout treatments together produced similar results to adding either alone. Results from a comparative field study of six other stream sites in the region corroborated the experimental findings, showing that at invaded sites rainbow trout usurped the terrestrial prey subsidy, causing a more than 75% decrease in the biomass of terrestrial invertebrates in Dolly Varden diets and forcing them to shift their foraging to insects on the stream bottom. Moreover, at sites with even low densities of rainbow trout, biomass of Dolly Varden was more than 75% lower than at sites without rainbow trout. Disruption of resource fluxes between habitats may be a common, but unidentified, consequence of invasions, and an additional mechanism contributing to the loss of native species

  10. Prey detection by vomeronasal chemoreception in a plethodontid salamander.

    PubMed

    Placyk, John S; Graves, Brent M

    2002-05-01

    While chemoreception is involved in a wide variety of salamander behaviors, the chemosensory system that mediates specific behaviors is rarely known. We investigated the role of the vomeronasal system (VNS) in foraging behavior of the red-backed salamander (Plethodon cinereus) by manipulating salamanders' abilities to detect nonvolatile chemical cues emitted by potential prey. Subjects received one of three treatments: (1) impaired vomeronasal system, (2) sham manipulation, and (3) no manipulation. The role of the VNS in mediating foraging on motile prey (Drosophila melanogaster) was investigated under three light conditions (bright, dim, dark). Salamanders with impaired VNSs foraged less efficiently than either of the other experimental groups by displaying the longest latency to attack and the lowest rate of prey capture, especially in the absence of visual cues. A second experiment utilized freshly killed prey to determine whether the VNS takes on added importance in the absence of visual or tactile cues associated with moving prey. Animals with impaired VNSs showed a decreased foraging efficiency on stationary prey under both dark and light conditions. In addition, a mark-recapture study of VNS-impaired and sham salamanders in the field also indicated that salamanders with impaired VNSs consumed fewer stationary prey compared to shams. The study indicates that the VNS plays a substantial role in the foraging behavior of the plethodontid salamander, P. cinereus.

  11. A snail-eating snake recognizes prey handedness

    PubMed Central

    Danaisawadi, Patchara; Asami, Takahiro; Ota, Hidetoshi; Sutcharit, Chirasak; Panha, Somsak

    2016-01-01

    Specialized predator-prey interactions can be a driving force for their coevolution. Southeast Asian snail-eating snakes (Pareas) have more teeth on the right mandible and specialize in predation on the clockwise-coiled (dextral) majority in shelled snails by soft-body extraction. Snails have countered the snakes’ dextral-predation by recurrent coil reversal, which generates diverse counterclockwise-coiled (sinistral) prey where Pareas snakes live. However, whether the snake predator in turn evolves any response to prey reversal is unknown. We show that Pareas carinatus living with abundant sinistrals avoids approaching or striking at a sinistral that is more difficult and costly to handle than a dextral. Whenever it strikes, however, the snake succeeds in predation by handling dextral and sinistral prey in reverse. In contrast, P. iwasakii with little access to sinistrals on small peripheral islands attempts and frequently misses capturing a given sinistral. Prey-handedness recognition should be advantageous for right-handed snail-eating snakes where frequently encountering sinistrals. Under dextral-predation by Pareas snakes, adaptive fixation of a prey population for a reversal gene instantaneously generates a sinistral species because interchiral mating is rarely possible. The novel warning, instead of sheltering, effect of sinistrality benefitting both predators and prey could further accelerate single-gene ecological speciation by left-right reversal. PMID:27046345

  12. Disentangling mite predator-prey relationships by multiplex PCR.

    PubMed

    Pérez-Sayas, Consuelo; Pina, Tatiana; Gómez-Martínez, María A; Camañes, Gemma; Ibáñez-Gual, María V; Jaques, Josep A; Hurtado, Mónica A

    2015-11-01

    Gut content analysis using molecular techniques can help elucidate predator-prey relationships in situations in which other methodologies are not feasible, such as in the case of trophic interactions between minute species such as mites. We designed species-specific primers for a mite community occurring in Spanish citrus orchards comprising two herbivores, the Tetranychidae Tetranychus urticae and Panonychus citri, and six predatory mites belonging to the Phytoseiidae family; these predatory mites are considered to be these herbivores' main biological control agents. These primers were successfully multiplexed in a single PCR to test the range of predators feeding on each of the two prey species. We estimated prey DNA detectability success over time (DS50), which depended on the predator-prey combination and ranged from 0.2 to 18 h. These values were further used to weight prey detection in field samples to disentangle the predatory role played by the most abundant predators (i.e. Euseius stipulatus and Phytoseiulus persimilis). The corrected predation value for E. stipulatus was significantly higher than for P. persimilis. However, because this 1.5-fold difference was less than that observed regarding their sevenfold difference in abundance, we conclude that P. persimilis is the most effective predator in the system; it preyed on tetranychids almost five times more frequently than E. stipulatus did. The present results demonstrate that molecular tools are appropriate to unravel predator-prey interactions in tiny species such as mites, which include important agricultural pests and their predators.

  13. Disentangling mite predator-prey relationships by multiplex PCR.

    PubMed

    Pérez-Sayas, Consuelo; Pina, Tatiana; Gómez-Martínez, María A; Camañes, Gemma; Ibáñez-Gual, María V; Jaques, Josep A; Hurtado, Mónica A

    2015-11-01

    Gut content analysis using molecular techniques can help elucidate predator-prey relationships in situations in which other methodologies are not feasible, such as in the case of trophic interactions between minute species such as mites. We designed species-specific primers for a mite community occurring in Spanish citrus orchards comprising two herbivores, the Tetranychidae Tetranychus urticae and Panonychus citri, and six predatory mites belonging to the Phytoseiidae family; these predatory mites are considered to be these herbivores' main biological control agents. These primers were successfully multiplexed in a single PCR to test the range of predators feeding on each of the two prey species. We estimated prey DNA detectability success over time (DS50), which depended on the predator-prey combination and ranged from 0.2 to 18 h. These values were further used to weight prey detection in field samples to disentangle the predatory role played by the most abundant predators (i.e. Euseius stipulatus and Phytoseiulus persimilis). The corrected predation value for E. stipulatus was significantly higher than for P. persimilis. However, because this 1.5-fold difference was less than that observed regarding their sevenfold difference in abundance, we conclude that P. persimilis is the most effective predator in the system; it preyed on tetranychids almost five times more frequently than E. stipulatus did. The present results demonstrate that molecular tools are appropriate to unravel predator-prey interactions in tiny species such as mites, which include important agricultural pests and their predators. PMID:25824504

  14. Tonically immobilized selfish prey can survive by sacrificing others.

    PubMed

    Miyatake, Takahisa; Nakayama, Satoshi; Nishi, Yusuke; Nakajima, Shuhei

    2009-08-01

    Death-feigning, also called tonic immobility, is found in a number of animal species across vertebrate and invertebrate taxa. To date, five hypotheses have been proposed for the adaptive significance of tonic immobility. These are that tonic immobility is effective for prey because (i) avoiding dead prey is safer for predators, (ii) immobility plays a role in physical defence, (iii) immobility plays a role in concealment and/or background matching, (iv) predators lose interest in unmoving prey, and (v) the characteristic immobilization posture signals a bad taste to predators. The fourth and fifth hypotheses have been considered suitable explanations for tonic immobility of the red flour beetle against its predator, the jumping spider. In the present study, we used chemical analyses of secretions by the red flour beetles under attack by the jumping spider to reject the fifth hypothesis for this system. More importantly, we tested a selfish-prey hypothesis for the adaptive significance of death-feigning as an anti-predator strategy, in which individuals adopting tonic immobility survive by sacrificing neighbours. Findings showed that survival rates of feigners were higher when in the presence of non-feigners or prey of a different species, compared to when alone, thus confirming our selfish-prey hypothesis. In summary, our results suggest that immobility following a spider attack is selfish; death-feigning prey increase their probability of survival at the expense of more mobile neighbours. PMID:19403540

  15. Predator pursuit strategies: how do falcons and hawks chase prey?

    NASA Astrophysics Data System (ADS)

    Kane, Suzanne Amador; Zamani, Marjon; Fulton, Andrew; Rosenthal, Lee

    2014-03-01

    This study reports on experiments on falcons, goshawks and red-tailed hawks wearing miniature videocameras mounted on their backs or heads while pursuing flying or ground-based prey. Videos of hunts recorded by the raptors were analyzed to determine apparent prey positions on their visual fields during pursuits. These video data then were interpreted using computer simulations of pursuit steering laws observed in insects and mammals. A comparison of the empirical and modeling data indicates that falcons use cues due to the apparent motion of prey on the falcon's visual field to track and capture flying prey via a form of motion camouflage. The falcons also were found to maintain their prey's image at visual angles consistent with using their shallow fovea. Results for goshawks and red-tailed hawks were analyzed for a comparative study of how pursuits of ground-based prey by accipeters and buteos differ from those used by falcons chasing flying prey. These results should prove relevant for understanding the coevolution of pursuit and evasion, as well as the development of computer models of predation on flocks,and the integration of sensory and locomotion systems in biomimetic robots.

  16. A snail-eating snake recognizes prey handedness.

    PubMed

    Danaisawadi, Patchara; Asami, Takahiro; Ota, Hidetoshi; Sutcharit, Chirasak; Panha, Somsak

    2016-01-01

    Specialized predator-prey interactions can be a driving force for their coevolution. Southeast Asian snail-eating snakes (Pareas) have more teeth on the right mandible and specialize in predation on the clockwise-coiled (dextral) majority in shelled snails by soft-body extraction. Snails have countered the snakes' dextral-predation by recurrent coil reversal, which generates diverse counterclockwise-coiled (sinistral) prey where Pareas snakes live. However, whether the snake predator in turn evolves any response to prey reversal is unknown. We show that Pareas carinatus living with abundant sinistrals avoids approaching or striking at a sinistral that is more difficult and costly to handle than a dextral. Whenever it strikes, however, the snake succeeds in predation by handling dextral and sinistral prey in reverse. In contrast, P. iwasakii with little access to sinistrals on small peripheral islands attempts and frequently misses capturing a given sinistral. Prey-handedness recognition should be advantageous for right-handed snail-eating snakes where frequently encountering sinistrals. Under dextral-predation by Pareas snakes, adaptive fixation of a prey population for a reversal gene instantaneously generates a sinistral species because interchiral mating is rarely possible. The novel warning, instead of sheltering, effect of sinistrality benefitting both predators and prey could further accelerate single-gene ecological speciation by left-right reversal. PMID:27046345

  17. Tonically immobilized selfish prey can survive by sacrificing others

    PubMed Central

    Miyatake, Takahisa; Nakayama, Satoshi; Nishi, Yusuke; Nakajima, Shuhei

    2009-01-01

    Death-feigning, also called tonic immobility, is found in a number of animal species across vertebrate and invertebrate taxa. To date, five hypotheses have been proposed for the adaptive significance of tonic immobility. These are that tonic immobility is effective for prey because (i) avoiding dead prey is safer for predators, (ii) immobility plays a role in physical defence, (iii) immobility plays a role in concealment and/or background matching, (iv) predators lose interest in unmoving prey, and (v) the characteristic immobilization posture signals a bad taste to predators. The fourth and fifth hypotheses have been considered suitable explanations for tonic immobility of the red flour beetle against its predator, the jumping spider. In the present study, we used chemical analyses of secretions by the red flour beetles under attack by the jumping spider to reject the fifth hypothesis for this system. More importantly, we tested a selfish-prey hypothesis for the adaptive significance of death-feigning as an anti-predator strategy, in which individuals adopting tonic immobility survive by sacrificing neighbours. Findings showed that survival rates of feigners were higher when in the presence of non-feigners or prey of a different species, compared to when alone, thus confirming our selfish-prey hypothesis. In summary, our results suggest that immobility following a spider attack is selfish; death-feigning prey increase their probability of survival at the expense of more mobile neighbours. PMID:19403540

  18. Phylogenetic signal in predator-prey body-size relationships.

    PubMed

    Naisbit, Russell E; Kehrli, Patrik; Rohr, Rudolf P; Bersier, Louis-Félix

    2011-12-01

    Body mass is a fundamental characteristic that affects metabolism, life history, and population abundance and frequently sets bounds on who eats whom in food webs. Based on a collection of topological food webs, Ulrich Brose and colleagues presented a general relationship between the body mass of predators and their prey and analyzed how mean predator-prey body-mass ratios differed among habitats and predator metabolic categories. Here we show that the general body-mass relationship conceals significant variation associated with both predator and prey phylogeny. Major-axis regressions between the log body mass of predators and prey differed among taxonomic groups. The global pattern for Kingdom Animalia had slope > 1, but phyla and classes varied, and several had slopes significantly < 1. The predator-prey body-mass ratio can therefore decrease or increase with increasing body mass, depending on the taxon considered. We also found a significant phylogenetic signal in analyses of prey body-mass range for predators and predator body-mass range for prey, with stronger signal in the former. Besides providing insights into how characteristics of trophic interactions evolve, our results emphasize the need to integrate phylogeny to improve models of community structure and dynamics or to achieve a metabolic theory of food-web ecology.

  19. Epoxy coating and other protective measures for reinforceing steel embedded in concrete subjected to a chloride laden environment

    NASA Astrophysics Data System (ADS)

    Kondratova, Irina

    1999-11-01

    Corrosion of steel reinforcement is the most significant factor in the deterioration of reinforced concrete structures. Corrosion of reinforcing steel in marine structures and bridges is initiated mainly by chloride contamination. When steel starts to corrode, the cross section of the reinforcing bar becomes smaller, also the volume of corrosion products exerts a pressure on the concrete resulting in spalling of the concrete cover and directly exposing the steel to the corrosive agents, thus accelerating the corrosion process and further reducing the load carrying capacity of the concrete member. Although there are corrosion protective measures available to the concrete producer such as use of protective coatings on steel surface and use of corrosion inhibitors, a very limited amount of information exists on the comparative behavior of these common corrosion protection strategies in cracked concrete, especially in cracked high performance concrete (HPC). The relative effectiveness of different protection methods for steel reinforcement such as the use of new types of epoxy-coated reinforcement, galvanized reinforcement, and corrosion inhibitors was investigated in concrete with water-to-cement ratios of 0.60 and 0.40 and 0.25. Concrete slabs were uncracked and had preformed transverse cracks. The effect of water-to-cement ratio and crack widths on the rate of corrosion in precracked reinforced concrete slabs also was investigated. Testing was performed in the laboratory and in the field. It was found that cracked HPC concrete alone or with addition of corrosion inhibitors cannot provide sufficient corrosion protection for uncoated steel reinforcement in a chloride-laden environment and that additional protection to the reinforcing steel in the form of epoxy coating is necessary to provide long-term service life of the concrete structure.

  20. The recent Italian Consolidation Act on privacy: new measures for data protection.

    PubMed

    Conti, A

    2006-03-01

    In the light of the new Consolidation Act on privacy, in effect since January 2004, the author has made some observations in relation to the protection of data concerning health. Special focus has been given to an overall view of the new regulations. "Sensitive data" are seen as differing from health data, while always respecting the rights, the fundamental freedom and the dignity of the person involved. A central role continues to be played by the Controller, who has regulating and control powers.

  1. Heath Monitoring of Thermal Protection Systems - Preliminary Measurements and Design Specifications

    NASA Technical Reports Server (NTRS)

    Scott, D. A.; Price, D. C.

    2007-01-01

    The work reported here is the first stage of a project that aims to develop a health monitoring system for Thermal Protection Systems (TPS) that enables a vehicle to safely re-enter the Earth's atmosphere. The TPS health monitoring system is to be integrated into an existing acoustic emissions-based Concept Demonstrator, developed by CSIRO, which has been previously demonstrated for evaluating impact damage of aerospace systems.

  2. Predicting prey population dynamics from kill rate, predation rate and predator-prey ratios in three wolf-ungulate systems.

    PubMed

    Vucetich, John A; Hebblewhite, Mark; Smith, Douglas W; Peterson, Rolf O

    2011-11-01

    1. Predation rate (PR) and kill rate are both fundamental statistics for understanding predation. However, relatively little is known about how these statistics relate to one another and how they relate to prey population dynamics. We assess these relationships across three systems where wolf-prey dynamics have been observed for 41 years (Isle Royale), 19 years (Banff) and 12 years (Yellowstone). 2. To provide context for this empirical assessment, we developed theoretical predictions of the relationship between kill rate and PR under a broad range of predator-prey models including predator-dependent, ratio-dependent and Lotka-Volterra dynamics. 3. The theoretical predictions indicate that kill rate can be related to PR in a variety of diverse ways (e.g. positive, negative, unrelated) that depend on the nature of predator-prey dynamics (e.g. structure of the functional response). These simulations also suggested that the ratio of predator-to-prey is a good predictor of prey growth rate. That result motivated us to assess the empirical relationship between the ratio and prey growth rate for each of the three study sites. 4. The empirical relationships indicate that PR is not well predicted by kill rate, but is better predicted by the ratio of predator-to-prey. Kill rate is also a poor predictor of prey growth rate. However, PR and ratio of predator-to-prey each explained significant portions of variation in prey growth rate for two of the three study sites. 5. Our analyses offer two general insights. First, Isle Royale, Banff and Yellowstone are similar insomuch as they all include wolves preying on large ungulates. However, they also differ in species diversity of predator and prey communities, exploitation by humans and the role of dispersal. Even with the benefit of our analysis, it remains difficult to judge whether to be more impressed by the similarities or differences. This difficulty nicely illustrates a fundamental property of ecological

  3. Predicting prey population dynamics from kill rate, predation rate and predator-prey ratios in three wolf-ungulate systems.

    PubMed

    Vucetich, John A; Hebblewhite, Mark; Smith, Douglas W; Peterson, Rolf O

    2011-11-01

    1. Predation rate (PR) and kill rate are both fundamental statistics for understanding predation. However, relatively little is known about how these statistics relate to one another and how they relate to prey population dynamics. We assess these relationships across three systems where wolf-prey dynamics have been observed for 41 years (Isle Royale), 19 years (Banff) and 12 years (Yellowstone). 2. To provide context for this empirical assessment, we developed theoretical predictions of the relationship between kill rate and PR under a broad range of predator-prey models including predator-dependent, ratio-dependent and Lotka-Volterra dynamics. 3. The theoretical predictions indicate that kill rate can be related to PR in a variety of diverse ways (e.g. positive, negative, unrelated) that depend on the nature of predator-prey dynamics (e.g. structure of the functional response). These simulations also suggested that the ratio of predator-to-prey is a good predictor of prey growth rate. That result motivated us to assess the empirical relationship between the ratio and prey growth rate for each of the three study sites. 4. The empirical relationships indicate that PR is not well predicted by kill rate, but is better predicted by the ratio of predator-to-prey. Kill rate is also a poor predictor of prey growth rate. However, PR and ratio of predator-to-prey each explained significant portions of variation in prey growth rate for two of the three study sites. 5. Our analyses offer two general insights. First, Isle Royale, Banff and Yellowstone are similar insomuch as they all include wolves preying on large ungulates. However, they also differ in species diversity of predator and prey communities, exploitation by humans and the role of dispersal. Even with the benefit of our analysis, it remains difficult to judge whether to be more impressed by the similarities or differences. This difficulty nicely illustrates a fundamental property of ecological

  4. Comparative study of European tunnel emergency-stop-area-wall protection measures.

    PubMed

    Kunc, Robert; Omerović, Senad; Ambrož, Miha; Prebil, Ivan

    2014-02-01

    Due to the increasing number of traffic accidents involving the collisions of vehicles with the emergency-stop-area head walls in tunnels, a comparative numerical analysis in accordance with the EN 1317 standard has been performed in order to assess the quality of the available protective safety barriers. Based on the simulation results, the values of the relevant injury criteria - the acceleration severity index (ASI), the theoretical head impact velocity (THIV) and the post-impact head deceleration (PHD) - were computed for several collision scenarios involving two different passenger vehicles colliding with two different safety barriers in various ways. The results show that due to the geometrical restrictions in the tunnel's emergency stop area none of the barriers can provide total protection for the occupants of the vehicle in the event of a collision. The installation of a steel-sheet-tube crash cushion was, however, found to provide the best possible protection within the given limitations. The results of the analysis were the basis for selecting a safety-barrier design for existing tunnel installations and for the proposed changes in regulations governing the geometry of the tunnel's emergency stop area.

  5. Predator cannibalism can intensify negative impacts on heterospecific prey.

    PubMed

    Takatsu, Kunio; Kishida, Osamu

    2015-07-01

    Although natural populations consist of individuals with different traits, and the degree of phenotypic variation varies among populations, the impact of phenotypic variation on ecological interactions has received little attention, because traditional approaches to community ecology assume homogeneity of individuals within a population. Stage structure, which is a common way of generating size and developmental variation within predator populations, can drive cannibalistic interactions, which can affect the strength of predatory effects on the predator's heterospecific prey. Studies have shown that predator cannibalism weakens predatory effects on heterospecific prey by reducing the size of the predator population and by inducing less feeding activity of noncannibal predators. We predict, however, that predator cannibalism, by promoting rapid growth of the cannibals, can also intensify predation pressure on heterospecific prey, because large predators have large resource requirements and may utilize a wider variety of prey species. To test this hypothesis, we conducted an experiment in which we created carnivorous salamander (Hynobius retardatus) populations with different stage structures by manipulating the salamander's hatch timing (i.e., populations with large or small variation in the timing of hatching), and explored the resultant impacts on the abundance, behavior, morphology, and life history of the salamander's large heterospecific prey, Rana pirica frog tadpoles. Cannibalism was rare in salamander populations having small hatch-timing variation, but was frequent in those having large hatch-timing variation. Thus, giant salamander cannibals occurred only in the latter. We clearly showed that salamander giants exerted strong predation pressure on frog tadpoles, which induced large behavioral and morphological defenses in the tadpoles and caused them to metamorphose late at large size. Hence, predator cannibalism arising from large variation in the timing

  6. Sensorimotor model of bat echolocation and prey capture.

    PubMed

    Kuc, R

    1994-10-01

    A model of the bat sensorimotor system is developed using acoustics, signal processing, and control theory to illustrate the fundamental issues in accomplishing prey capture with echolocation. This model indicates that successful nonpredictive tracking of an ideal prey can be accomplished with a very simple system. Circular apertures approximate the mouth and ears for deriving acoustic beam patterns, using the big brown bat Eptesicus fuscus as a model. Fundamental and overtone frequency components in the emissions allow two simultaneous acoustic beams to be defined. A pair of nonlinear, time-variable, sampled-data controllers alter the bat's heading by applying yaw and pitch heading corrections. The yaw correction attempts to position the prey in the midsagittal plane by nulling the interaural intensity difference of the fundamental component. The pitch correction compares the intensities of the overtone and fundamental components and acts to null their difference. By initiating pitch correction when the overtone intensity first exceeds that of the fundamental, the ambiguity problem is solved and the prey is directed to the capture region. Simulations of passive prey capture indicate that the capture probability decreases as the prey speed increases. Both quick and sluggish prey are considered, with sluggish prey found to be caught with slightly better efficiency. The magnitude of the prey's lateral motion just prior to capture is observed to be an important factor determining capture. The presence of a blind stage is considered, during which the interference of the emission with the echo is assumed to disrupt any sonar information. The presence of such a blind stage is found to have negligible effect on capture efficiency.

  7. Assessment of the Coupled Heat and Mass Transfer Through Protective Garments Using Manikins and Other Advanced Measurement Devices

    NASA Astrophysics Data System (ADS)

    Rossi, René M.; Psikuta, Agnes

    The assessment of the coupled heat and mass transfer in protective clothing is very complex as the layers of the system are a combination of fabric and air layers that constantly change with the movements of the wearer. The methods to measure these mechanisms become more and more sophisticated which increases the precision of models to predict the impact of heat and moisture fluxes on the human thermal physiology. The simulation of the human thermoregulatory mechanisms requires the combination of physical models representing the body (manikins) with physiological (mathematical) models. This chapter gives different examples of advanced measurement methods to characterize the thermal properties of fabrics and garments.

  8. The Role of Motion Extrapolation in Amphibian Prey Capture

    PubMed Central

    2015-01-01

    Sensorimotor delays decouple behaviors from the events that drive them. The brain compensates for these delays with predictive mechanisms, but the efficacy and timescale over which these mechanisms operate remain poorly understood. Here, we assess how prediction is used to compensate for prey movement that occurs during visuomotor processing. We obtained high-speed video records of freely moving, tongue-projecting salamanders catching walking prey, emulating natural foraging conditions. We found that tongue projections were preceded by a rapid head turn lasting ∼130 ms. This motor lag, combined with the ∼100 ms phototransduction delay at photopic light levels, gave a ∼230 ms visuomotor response delay during which prey typically moved approximately one body length. Tongue projections, however, did not significantly lag prey position but were highly accurate instead. Angular errors in tongue projection accuracy were consistent with a linear extrapolation model that predicted prey position at the time of tongue contact using the average prey motion during a ∼175 ms period one visual latency before the head movement. The model explained successful strikes where the tongue hit the fly, and unsuccessful strikes where the fly turned and the tongue hit a phantom location consistent with the fly's earlier trajectory. The model parameters, obtained from the data, agree with the temporal integration and latency of retinal responses proposed to contribute to motion extrapolation. These results show that the salamander predicts future prey position and that prediction significantly improves prey capture success over a broad range of prey speeds and light levels. SIGNIFICANCE STATEMENT Neural processing delays cause actions to lag behind the events that elicit them. To cope with these delays, the brain predicts what will happen in the future. While neural circuits in the retina and beyond have been suggested to participate in such predictions, few behaviors have been

  9. Consumptive and nonconsumptive effects of predators on metacommunities of competing prey.

    PubMed

    Orrock, John L; Grabowski, Jonathan H; Pantel, Jelena H; Peacor, Scott D; Peckarsky, Barbara L; Sih, Andrew; Werner, Earl E

    2008-09-01

    Although predators affect prey both via consumption and by changing prey migration behavior, the interplay between these two effects is rarely incorporated into spatial models of predator-prey dynamics and competition among prey. We develop a model where generalist predators have consumptive effects (i.e., altering the likelihood of local prey extinction) as well as nonconsumptive effects (altering the likelihood of colonization) on spatially separated prey populations (metapopulations). We then extend this model to explore the effects of predators on competition among prey. We find that generalist predators can promote persistence of prey metapopulations by promoting prey colonization, but predators can also hasten system-wide extinction by either increasing local extinction or reducing prey migration. By altering rates of prey migration, predators in one location can exert remote control over prey dynamics in another location via predator-mediated changes in prey flux. Thus, the effect of predators may extend well beyond the proportion of patches they visit. In the context of prey metacommunities, predator-mediated shifts in prey migration and mortality can shift the competition-colonization trade-off among competing prey, leading to changes in the prey community as well as changes in the susceptibility of prey species to habitat loss. Consequently, native prey communities may be susceptible to invasion not only by exotic prey species that experience reduced amounts of mortality from resident predators, but also by exotic prey species that exhibit strong dispersal in response to generalist native predators. Ultimately, our work suggests that the consumptive and nonconsumptive effects of generalist predators may have strong, yet potentially cryptic, effects on competing prey capable of mediating coexistence, fostering invasion, and interacting with anthropogenic habitat alteration.

  10. Cell-cycle progress in obligate predatory bacteria is dependent upon sequential sensing of prey recognition and prey quality cues

    PubMed Central

    Rotem, Or; Pasternak, Zohar; Shimoni, Eyal; Belausov, Eduard; Porat, Ziv; Pietrokovski, Shmuel; Jurkevitch, Edouard

    2015-01-01

    Predators feed on prey to acquire the nutrients necessary to sustain their survival, growth, and replication. In Bdellovibrio bacteriovorus, an obligate predator of Gram-negative bacteria, cell growth and replication are tied to a shift from a motile, free-living phase of search and attack to a sessile, intracellular phase of growth and replication during which a single prey cell is consumed. Engagement and sustenance of growth are achieved through the sensing of two unidentified prey-derived cues. We developed a novel ex vivo cultivation system for B. bacteriovorus composed of prey ghost cells that are recognized and invaded by the predator. By manipulating their content, we demonstrated that an early cue is located in the prey envelope and a late cue is found within the prey soluble fraction. These spatially and temporally separated cues elicit discrete and combinatory regulatory effects on gene transcription. Together, they delimit a poorly characterized transitory phase between the attack phase and the growth phase, during which the bdelloplast (the invaded prey cell) is constructed. This transitory phase constitutes a checkpoint in which the late cue presumably acts as a determinant of the prey’s nutritional value before the predator commits. These regulatory adaptations to a unique bacterial lifestyle have not been reported previously. PMID:26487679

  11. Sizes of prey consumed by two pelagic predators in US reservoirs: Implications for quantifying biomass of available prey

    USGS Publications Warehouse

    Dennerline, D.E.; Van Den Avyle, M.J.

    2000-01-01

    Striped bass Morone saxatilis and hybrid bass M. saxatilis x M. chrysops have been stocked to establish fisheries in many US reservoirs, but success has been limited by a poor understanding of relations between prey biomass and predator growth and survival. To define sizes of prey that are morphologically available, we developed predictive relationships between predator length, mouth dimensions, and expected maximum prey size; predictions were then validated using published data on sizes of clupeid prey (Dorosoma spp.) in five US reservoirs. Further, we compared the biomass of prey considered available to predators using two forms of a length-based consumption model - a previously published AP/P ratio and a revised model based on our results. Predictions of maximum prey size using predator GW were consistent with observed prey sizes in US reservoirs. Length of consumed Dorosoma was significantly, but weakly, correlated with predator length in four of the five reservoirs (r2 = 0.006-0.336, P 150 mm TL) were abundant. (C) 2000 Elsevier Science B.V.

  12. Difficulties in relating Cd concentrations in the predatory insect Chaoborus to those of its prey in nature

    USGS Publications Warehouse

    Croteau, M.-N.; Hare, L.; Tessier, A.

    2003-01-01

    Because Chaoborus larvae take up most of their cadmium (Cd) from food, we tested the hypothesis that Cd concentrations in this insect are directly related to those in their planktonic prey. We measured Cd in Chaoborus and in Zooplankton collected from 24 eastern Canadian lakes varying widely in their Cd concentrations. Cd concentrations in the predator were not correlated with those in bulk zooplankton, whether separated into size fractions liable to be eaten by Chaoborus or not. In highly acidic lakes, Cd concentrations in Chaoborus did not respond to increases in zooplankton Cd because of either competition between H and Cd ions at Cd absorption sites in the predator's gut or differences in prey community composition between highly acidic and circumneutral lakes. Relationships between Cd in Chaoborus and in its potential prey were stronger when we used Cd concentrations for specific crustacean taxa in a mechanistic model. We conclude that predictive relationships between metal concentrations in predators and their prey are likely to be strongest if the subset of prey consumed by the predator has been characterized and if this information is used in a bioaccumulation model.

  13. Consequences of seasonal variation in reservoir water level for predatory fishes: linking visual foraging and prey densities

    USGS Publications Warehouse

    Klobucar, Stephen L.; Budy, Phaedra

    2016-01-01

    In reservoirs, seasonal drawdown can alter the physical environment and may influence predatory fish performance. We investigated the performance of lake trout (Salvelinus namaycush) in a western reservoir by coupling field measurements with visual foraging and bioenergetic models at four distinct states (early summer, mid-summer, late summer, and fall). The models suggested that lake trout prey, juvenile kokanee (Oncorhynchus nerka), are limited seasonally by suitable temperature and dissolved oxygen. Accordingly, prey densities were greatest in late summer when reservoir volume was lowest and fish were concentrated by stratification. Prey encounter rates (up to 68 fish·day−1) and predator consumption are also predicted to be greatest during late summer. However, our models suggested that turbidity negatively correlates with prey detection and consumption across reservoir states. Under the most turbid conditions, lake trout did not meet physiological demands; however, during less turbid periods, predator consumption reached maximum bioenergetic efficiency. Overall, our findings demonstrate that rapid reservoir fluctuations and associated abiotic conditions can influence predator–prey interactions, and our models describe the potential impacts of water level fluctuation on valuable sport fishes.

  14. Tiger beetles pursue prey using a proportional control law with a delay of one half-stride

    PubMed Central

    Haselsteiner, Andreas F.; Gilbert, Cole; Wang, Z. Jane

    2014-01-01

    Tiger beetles are fast diurnal predators capable of chasing prey under closed-loop visual guidance. We investigated this control system using statistical analyses of high-speed digital recordings of beetles chasing a moving prey dummy in a laboratory arena. Correlation analyses reveal that the beetle uses a proportional control law in which the angular position of the prey relative to the beetle's body axis drives the beetle's angular velocity with a delay of about 28 ms. The proportionality coefficient or system gain, 12 s−1, is just below critical damping. Pursuit simulations using the derived control law predict angular orientation during pursuits with a residual error of about 7°. This is of the same order of magnitude as the oscillation imposed by the beetle's alternating tripod gait, which was not factored into the control law. The system delay of 28 ms equals a half-stride period, i.e. the time between the touch down of alternating tripods. Based on these results, we propose a physical interpretation of the observed control law: to turn towards its prey, the beetle on average exerts a sideways force proportional to the angular position of the prey measured a half-stride earlier. PMID:24718454

  15. Feeding on prey increases photosynthetic efficiency in the carnivorous sundew Drosera capensis

    PubMed Central

    Pavlovič, Andrej; Krausko, Miroslav; Libiaková, Michaela; Adamec, Lubomír

    2014-01-01

    Backround and Aims It has been suggested that the rate of net photosynthesis (AN) of carnivorous plants increases in response to prey capture and nutrient uptake; however, data confirming the benefit from carnivory in terms of increased AN are scarce and unclear. The principal aim of our study was to investigate the photosynthetic benefit from prey capture in the carnivorous sundew Drosera capensis. Methods Prey attraction experiments were performed, with measurements and visualization of enzyme activities, elemental analysis and pigment quantification together with simultaneous measurements of gas exchange and chlorophyll a fluorescence in D. capensis in response to feeding with fruit flies (Drosophila melanogaster). Key Results Red coloration of tentacles did not act as a signal to attract fruit flies onto the traps. Phosphatase, phophodiesterase and protease activities were induced 24 h after prey capture. These activities are consistent with the depletion of phosphorus and nitrogen from digested prey and a significant increase in their content in leaf tissue after 10 weeks. Mechanical stimulation of tentacle glands alone was not sufficient to induce proteolytic activity. Activities of β-D-glucosidases and N-acetyl-β-D-glucosaminidases in the tentacle mucilage were not detected. The uptake of phosphorus from prey was more efficient than that of nitrogen and caused the foliar N:P ratio to decrease; the contents of other elements (K, Ca, Mg) decreased slightly in fed plants. Increased foliar N and P contents resulted in a significant increase in the aboveground plant biomass, the number of leaves and chlorophyll content as well as AN, maximum quantum yield (Fv/Fm) and effective photochemical quantum yield of photosystem II (ΦPSII). Conclusions According to the stoichiometric relationships among different nutrients, the growth of unfed D. capensis plants was P-limited. This P-limitation was markedly alleviated by feeding on fruit flies and resulted in improved

  16. Trophic relay and prey switching - A stomach contents and calorimetric investigation of an ambassid fish and their saltmarsh prey

    NASA Astrophysics Data System (ADS)

    McPhee, Jack J.; Platell, Margaret E.; Schreider, Maria J.

    2015-12-01

    Trophic relay is an ecological model that involves the movement of biomass and energy from vegetation, such as saltmarshes, within estuaries to the open sea via a series of predator-prey relationships. Any potential for trophic relay is therefore affected by water movements within an estuary and by the ability of a predator to "switch" prey in response to fluctuating abundances of those prey. Saltmarsh-dwelling grapsid crabs, which feed on saltmarsh-derived detritus and microphytobenthos, release zoeae into ebbing tides that inundate saltmarshes during spring-tide cycles within tidally-dominated estuaries, such as Brisbane Water Estuary, therefore providing an opportunity to examine whether prey-switching and/or trophic relay may occur in fish that feed on those zoeae (such as the highly abundant estuarine ambassid, Ambassis jacksoniensis). This model was examined by sampling A. jacksoniensis near saltmarshes in a large, temperate south-eastern Australian estuary during flood and ebb tides on days of saltmarsh inundation and non-inundation over four spring-tide events in 2012. Stomach fullnesses of A. jacksoniensis were generally highest during ebb tides on days of saltmarsh inundation, implying that feeding was most marked at these times. Caridean decapods dominated diets during flood tides and on days of no saltmarsh inundation, while crab zoeae dominated diets during ebb tides and on days of inundation, suggesting that, when saltmarsh-derived zoeae became abundant, A. jacksoniensis switched to feeding on those prey. Three potential zooplankton prey (calanoid copepods, caridean decapods and crab zoeae) did not differ calorimetrically, indicating that switching of prey by A. jacksoniensis is not directly related to their preying on energetically greater prey, but reflects opportunistic feeding on more abundant and/or less elusive prey. As A. jacksoniensis is able to switch prey from estuarine caridean decapods to saltmarsh-derived crab zoeae, this very abundant

  17. Criteria for protected areas and other conservation measures in the Antarctic region

    SciTech Connect

    Angel, M.V.

    1987-01-01

    The Antarctic region is threatened by three major anthropogenic influences: climatic change brought about by increases in atmospheric carbon dioxide, the effects of persistent pollutants carried into the region via atmosphere and ocean, and the increase in Man's activities. These include radioactive wastes, organochlorides, freons, PCBs and heavy metals. Vulnerable ecosystems can be considered as those which are under direct pressure from Man's activities, whereas fragile ecosystems are the more likely to suffer irreversible change when perturbed, but are not necessarily threatened at present. Three of the main habitat types, terrestrial, inland waters, and islands, are likely to be fragile. However, all these can be conserved reasonably adequately with a system of protected and managed areas, so long as the area covered is adequate and representative. The fourth habitat type, the oceanic ecosystem, contains few fragile elements because it is dominated by the highly dynamic physical oceanic processes. Elements of the ecosystem are vulnerable to further exploitation, and although only the whales and some of the fish stocks can be regarded as fragile, there is considerably uncertainty as what synergistic effect exploitation of apparently key elements of the ecosystem, such as the krill, will have on other important components of the communities. The highly dynamic structure of oceanic environments renders the concept of conservation based on limited protected areas developed for terrestrial environments ineffective in the majority of marine environments. Instead the whole marine environment of the Antarctic region must be considered to be a single entity and managed as such.

  18. Pharmacokinetics of gentamicin in birds of prey.

    PubMed

    Bird, J E; Miller, K W; Larson, A A; Duke, G E

    1983-07-01

    The pharmacokinetics of gentamicin, including half-life, apparent volume of distribution, total body clearance, and fraction of drug absorbed from IM injection sites, were determined in 3 species of birds of prey (red-tailed hawks, great horned owls, and golden eagles). Significant differences (P less than 0.05) between species were found for the half-life and total body clearance values for this broad-spectrum antibiotic. The values for apparent volume of distribution and fraction absorbed did not differ among species and were similar to those reported in mammals. Rapid and relatively complete absorption from IM injection sites resulted in high bioavailability. After IV administration of 10 mg of gentamicin/kg of body weight, serum concentrations greater than 12 micrograms/ml were present for at least 2 hours and greater than 2 micrograms/ml for 4 to 6 hours. On the basis of the various determinations, an IM dose of 2.5 mg of gentamicin/kg given every 8 hours should provide therapeutic serum concentrations of gentamicin in the 3 species. PMID:6881663

  19. A FASTER METHOD OF MEASURING RECREATIONAL WATER QUALITY FOR BETTER PROTECTION OF SWIMMER'S HEALTH

    EPA Science Inventory

    Introduction

    Fecal indicator bacteria (FIB) are used to monitor recreational water quality worldwide. Current methods of measuring FIB require at least 24-hours for visible bacterial colonies to grow. We previously reported that a faster method (< 2 hours) of measuring FI...

  20. Nonlinearity in the predation risk of prey mobility.

    PubMed Central

    Banks, P B; Norrdahl, K; Korpimäki, E

    2000-01-01

    Odorous waste products such as urine and faeces are unavoidable for most animals and are widely exploited by predators and their prey. Consequently, waste accumulations can be risky and prey which increase their mobility in order to disperse and dilute their waste should avoid a high predation risk until this benefit is balanced by the increasing risks of random predator encounter. This hypothesis was tested for voles (Microtus spp.) in Finland which are vulnerable to predation due to the scent and ultraviolet attractiveness of their urine. The mortality and mobility of radio-collared voles showed a U-shaped relationship, regardless of vole sex, species or population cycle phase. The low risks for prey making intermediate movements suggest that predation risk can exert strong selective pressures on prey such that they have little respite from the risk of being killed. PMID:11467424

  1. Assessment of lead uptake in reptilian prey species.

    PubMed

    Inouye, Laura S; Yoo, Leslie J; Talent, Larry G; Clarke, Joan U; Jones, Robert P; Steevens, Jeffery A; Boyd, Robert E

    2007-07-01

    As part of an investigation determining the trophically available fraction of metals in a model terrestrial food web, i.e., invertebrate prey to Western fence lizards (Sceloporus occidentalis), we evaluated the ability of several invertebrate prey to bioaccumulate lead and to form metals-rich granules, which are hypothesized to be non-available to predators. Crickets (Acheta domestica), tenebroid beetle larvae (Tenebrio molitor), and isopods (Porcellio scaber) were selected as model prey organisms. Lack of standard exposure methodologies for these species has presented a barrier to trophic transfer evaluations, as each species has particular requirements that create challenges for designing exposure conditions. We were able to devise exposure conditions for all three species that allow long-term exposure studies. All prey organisms accumulated lead from contaminated food, and for all species the majority of the accumulated Pb was associated with the exoskeleton (>50%), with metals-rich granules accounting for most of the remaining accumulated lead. PMID:17490716

  2. Local Bifurcations and Optimal Theory in a Delayed Predator-Prey Model with Threshold Prey Harvesting

    NASA Astrophysics Data System (ADS)

    Tankam, Israel; Tchinda Mouofo, Plaire; Mendy, Abdoulaye; Lam, Mountaga; Tewa, Jean Jules; Bowong, Samuel

    2015-06-01

    We investigate the effects of time delay and piecewise-linear threshold policy harvesting for a delayed predator-prey model. It is the first time that Holling response function of type III and the present threshold policy harvesting are associated with time delay. The trajectories of our delayed system are bounded; the stability of each equilibrium is analyzed with and without delay; there are local bifurcations as saddle-node bifurcation and Hopf bifurcation; optimal harvesting is also investigated. Numerical simulations are provided in order to illustrate each result.

  3. Curvature facilitates prey fixation in predatory insect claws.

    PubMed

    Petie, Ronald; Muller, Mees

    2007-02-21

    Insects show a large variety in prey capture strategies, with a correspondingly large diversity in predatory adaptations. We studied a specific type of predatory claws, these can for example be found in praying mantis species. The claw is closeable over its entire length and the prey is fixed between the femur (upper arm) and the tibia (lower arm) of the insect leg. The morphology of these predatory claws is diverse. Some species have straight claws covered with spines, while other species have smooth, curved claws. We have studied the mechanics of this femur-tibia type of predatory insect claws, by making a physical model, eventually trying to explain why in some insect species the claws are curved instead of straight. The main results are (1) when comparing curved claws to straight claws, curvature leads to a strong reduction of forces driving the prey away from the pivoting point, thereby reducing the need for friction generating structures. (2) In the curved claw model a position exists where the resulting force on the prey is exactly zero. This is because the normal forces on the femur and tibia are opposed, and in line. At this position the prey is perfectly clamped and not driven out of the claw. This feature does not exist in straight claws. (3) In the curved claw, the prey cannot be placed at a position further than a certain maximum distance from the pivoting point. Near this maximum position, the resulting force on the prey reaches high values because moment arms are near zero. (4) Between the zero position and the maximum position the resulting force is directed toward the pivoting point, which stabilizes prey fixation. PMID:17056069

  4. Review Article: Structural flood-protection measures referring to several European case studies

    NASA Astrophysics Data System (ADS)

    Kryžanowski, A.; Brilly, M.; Rusjan, S.; Schnabl, S.

    2014-01-01

    The paper presents a review of structural measures that were taken to cope with floods in some cities along the Danube River, such as Vienna, Bratislava, and Belgrade. These cities were also considered as case studies within the KULTURisk project. The structural measures are reviewed and compared to each other according to the type, duration of application, the return period of the design flood event, how the project measures are integrated into spatial planning and the problems that occur in the flood defences today. Based on this review, some suggestions are given on how to improve the flood risk management in flood-prone areas.

  5. Ecological risk assessment of protected species at a military installation

    SciTech Connect

    Jones, M.L.; Faulk, S.T.; Lukin, C.; Kochel, M.J.

    1995-12-31

    A quantitative ecological risk assessment was performed to determine adverse effects posed by potential chemical contamination for two state-protected mammal species (Skull Valley pocket gopher and spotted bat) known to occur or potentially occur within the confines of the US Army Dugway Proving Ground, Utah. Surface soil and prey items were analyzed for metals and total petroleum hydrocarbons. Concentrations of the target analytes in forage were estimated. Receptor-specific biological parameters and the use of a geographic information system allowed the risk assessment to be tailored to the very different natural histories of the two mammals. A grid of interpolated soil concentrations was created for the entire base using measured soil concentrations and knowledge of site history. Spatially-averaged soil exposure concentrations were calculated using receptor home range areas. Doses were stochastically computed using the probability density functions of soil exposure concentration data, biomagnification factors, and measured prey concentration data. An extensive literature search provided the ecotoxicological benchmark values for the contaminants and hazard quotients were computed. The use of receptor-specific information and a geographic information system for spatial analysis of contaminant concentrations and animal exposure allowed a more precise estimate of risk for these two state-protected mammal species.

  6. Noisy predator-prey model explains oscillation patterns in sockeye salmon data.

    PubMed

    Schmitt, Christoph K; Wildner, Christian; Drossel, Barbara

    2016-01-21

    A model of sockeye salmon population dynamics that incorporates predator-prey dynamics in the nursery lakes, salmon migration and stochastic effects is compared to Fraser River sockeye salmon spawner numbers with respect to cyclic dominance. For this comparison we use a method developed by White et al. (2014) to calculate measures for the consistency and strength of cyclic dominance in the time series using its wavelet transform. We find that the model can match the oscillation patterns found in nature, both for persistently oscillating populations and for intermittent oscillations. It matches persistently oscillating populations much better than a model that does not incorporate predator-prey interaction. Persistent oscillations are more likely to occur in the model if the growth conditions for the sockeye fry are good and the coupling to the predator is strong. PMID:26551158

  7. Noisy predator-prey model explains oscillation patterns in sockeye salmon data.

    PubMed

    Schmitt, Christoph K; Wildner, Christian; Drossel, Barbara

    2016-01-21

    A model of sockeye salmon population dynamics that incorporates predator-prey dynamics in the nursery lakes, salmon migration and stochastic effects is compared to Fraser River sockeye salmon spawner numbers with respect to cyclic dominance. For this comparison we use a method developed by White et al. (2014) to calculate measures for the consistency and strength of cyclic dominance in the time series using its wavelet transform. We find that the model can match the oscillation patterns found in nature, both for persistently oscillating populations and for intermittent oscillations. It matches persistently oscillating populations much better than a model that does not incorporate predator-prey interaction. Persistent oscillations are more likely to occur in the model if the growth conditions for the sockeye fry are good and the coupling to the predator is strong.

  8. Snake modulates constriction in response to prey's heartbeat.

    PubMed

    Boback, Scott M; Hall, Allison E; McCann, Katelyn J; Hayes, Amanda W; Forrester, Jeffrey S; Zwemer, Charles F

    2012-06-23

    Many species of snakes use constriction-the act of applying pressure via loops of their trunk-to subdue and kill their prey. Constriction is costly and snakes must therefore constrict their prey just long enough to ensure death. However, it remains unknown how snakes determine when their prey is dead. Here, we demonstrate that boas (Boa constrictor) have the remarkable ability to detect a heartbeat in their prey and, based on this signal, modify the pressure and duration of constriction accordingly. We monitored pressure generated by snakes as they struck and constricted warm cadaveric rats instrumented with a simulated heart. Snakes responded to the beating heart by constricting longer and with greater total pressure than when constricting rats with no heartbeat. When the heart was stopped midway through the constriction, snakes abandoned constriction shortly after the heartbeat ceased. Furthermore, snakes naive to live prey also responded to the simulated heart, suggesting that this behaviour is at least partly innate. These results are an example of how snakes integrate physiological cues from their prey to modulate a complex and ancient behavioural pattern.

  9. Caste evolution and ecology: a special worker for novel prey.

    PubMed

    Powell, Scott; Franks, Nigel R

    2005-10-22

    Individual specialization underpins the division of labour within ant societies, but only in a small minority do morphological specialists, or physical castes, exist in the workforce. The genetic conditions that allow such castes to evolve are well understood, but the ecological pressures that select for them are not. We provide compelling evidence that the task of transporting novel prey selected for an exaggerated transport caste, or 'submajor', in the army ant Eciton burchellii. This species is the only Eciton that preys upon large arthropods as well as ants, the ancestral prey type, and by comparing load-transport among Eciton species and within E. burchellii, we show that this mixed diet significantly constrains transport efficiency. Crucially, however, we also show that E. burchellii submajors are highly specialized on transporting non-ant prey, and we demonstrate experientially that it is specifically this prey type that constrains prey-transport efficiency. Our study also suggests that phylogenetic constraints associated with the Eciton lifestyle intensified selection for the exaggerated submajor of E. burchellii. Thus, we propose that a novel task may only select for a special caste when phylogenetic constraints preclude the evolution of alternative solutions. This identifies a new and potentially general scenario for the evolution of physical castes.

  10. Indirect evolutionary rescue: prey adapts, predator avoids extinction

    PubMed Central

    Yamamichi, Masato; Miner, Brooks E

    2015-01-01

    Recent studies have increasingly recognized evolutionary rescue (adaptive evolution that prevents extinction following environmental change) as an important process in evolutionary biology and conservation science. Researchers have concentrated on single species living in isolation, but populations in nature exist within communities of interacting species, so evolutionary rescue should also be investigated in a multispecies context. We argue that the persistence or extinction of a focal species can be determined solely by evolutionary change in an interacting species. We demonstrate that prey adaptive evolution can prevent predator extinction in two-species predator–prey models, and we derive the conditions under which this indirect evolutionary interaction is essential to prevent extinction following environmental change. A nonevolving predator can be rescued from extinction by adaptive evolution of its prey due to a trade-off for the prey between defense against predation and population growth rate. As prey typically have larger populations and shorter generations than their predators, prey evolution can be rapid and have profound effects on predator population dynamics. We suggest that this process, which we term ‘indirect evolutionary rescue’, has the potential to be critically important to the ecological and evolutionary responses of populations and communities to dramatic environmental change. PMID:26366196

  11. Predator interference and stability of predator-prey dynamics.

    PubMed

    Přibylová, Lenka; Berec, Luděk

    2015-08-01

    Predator interference, that is, a decline in the per predator consumption rate as predator density increases, is generally thought to promote predator-prey stability. Indeed, this has been demonstrated in many theoretical studies on predator-prey dynamics. In virtually all of these studies, the stabilization role is demonstrated as a weakening of the paradox of enrichment. With predator interference, stable limit cycles that appear as a result of environmental enrichment occur for higher values of the environmental carrying capacity of prey, and even a complete absence of the limit cycles can happen. Here we study predator-prey dynamics using the Rosenzweig-MacArthur-like model in which the Holling type II functional response has been replaced by a predator-dependent family which generalizes many of the commonly used descriptions of predator interference. By means of a bifurcation analysis we show that sufficiently strong predator interference may bring about another stabilizing mechanism. In particular, hysteresis combined with (dis)appearance of stable limit cycles imply abrupt increases in both the prey and predator densities and enhanced persistence and resilience of the predator-prey system. We encourage refitting the previously collected data on predator consumption rates as well as for conducting further predation experiments to see what functional response from the explored family is the most appropriate.

  12. Indirect evolutionary rescue: prey adapts, predator avoids extinction.

    PubMed

    Yamamichi, Masato; Miner, Brooks E

    2015-09-01

    Recent studies have increasingly recognized evolutionary rescue (adaptive evolution that prevents extinction following environmental change) as an important process in evolutionary biology and conservation science. Researchers have concentrated on single species living in isolation, but populations in nature exist within communities of interacting species, so evolutionary rescue should also be investigated in a multispecies context. We argue that the persistence or extinction of a focal species can be determined solely by evolutionary change in an interacting species. We demonstrate that prey adaptive evolution can prevent predator extinction in two-species predator-prey models, and we derive the conditions under which this indirect evolutionary interaction is essential to prevent extinction following environmental change. A nonevolving predator can be rescued from extinction by adaptive evolution of its prey due to a trade-off for the prey between defense against predation and population growth rate. As prey typically have larger populations and shorter generations than their predators, prey evolution can be rapid and have profound effects on predator population dynamics. We suggest that this process, which we term 'indirect evolutionary rescue', has the potential to be critically important to the ecological and evolutionary responses of populations and communities to dramatic environmental change.

  13. Dynamics of Predator-Prey Metapopulations with Allee Effects.

    PubMed

    Fan, Meng; Wu, Ping; Feng, Zhilan; Swihart, Robert K

    2016-08-01

    Allee effects increasingly are recognized as influential determinants of population dynamics, especially in disturbed landscapes. We developed a predator-prey metapopulation model to study the impact of an Allee effect on predator-prey. The model incorporates habitat destruction and predators with imperfect information about prey distribution. Criteria are established for the existence and stability of equilibria, and the possible existence of a limit cycle is discussed. Numerical bifurcation analysis of the model is carried out to examine the impact of Allee effects as well as other key processes on trophic dynamics. Inclusion of Allee effects produces a richer array of dynamics than earlier models in which it was absent. When prey interacts with generalist predators, Allee effects operate synergistically to depress prey populations. Allee effects are more likely to depress occupancy levels when destruction of habitat patches is moderate; at severe levels of destruction, Allee effects are swamped by demographic effects of habitat loss. Stronger Allee effects correspond to lower thresholds of predator colonization rates at which prey become extinct. We discuss implications of our model for conservation of rare species as well as pest management via biocontrol.

  14. The impact of environmental toxins on predator-prey dynamics.

    PubMed

    Huang, Qihua; Wang, Hao; Lewis, Mark A

    2015-08-01

    Predators and prey may be simultaneously exposed to environmental toxins, but one may be more susceptible than the other. To study the effects of environmental toxins on food web dynamics, we develop a toxin-dependent predator-prey model that combines both direct and indirect toxic effects on two trophic levels. The direct effects of toxins typically reduce organism abundance by increasing mortality or reducing fecundity. Such direct effects, therefore, alter both bottom-up food availability and top-down predatory ability. However, the indirect effects, when mediated through predator-prey interactions, may lead to counterintuitive effects. This study investigates how the balance of the classical predator-prey dynamics changes as a function of environmental toxin levels. While high toxin concentrations are shown to be harmful to both species, possibly leading to extirpation of both species, intermediate toxin concentrations may affect predators disproportionately through biomagnification, leading to reduced abundance of predators and increased abundance of the prey. This counterintuitive effect significantly increases biomass at the lower trophic level. Environmental toxins may also reduce population variability by preventing populations from fluctuating around a coexistence equilibrium. Finally, environmental toxins may induce bistable dynamics, in which different initial population levels produce different long-term outcomes. Since our toxin-dependent predator-prey model is general, the theory developed here not only provides a sound foundation for population or community effects of toxicity, but also could be used to help develop management strategies to preserve and restore the integrity of contaminated habitats.

  15. Dynamics of Predator-Prey Metapopulations with Allee Effects.

    PubMed

    Fan, Meng; Wu, Ping; Feng, Zhilan; Swihart, Robert K

    2016-08-01

    Allee effects increasingly are recognized as influential determinants of population dynamics, especially in disturbed landscapes. We developed a predator-prey metapopulation model to study the impact of an Allee effect on predator-prey. The model incorporates habitat destruction and predators with imperfect information about prey distribution. Criteria are established for the existence and stability of equilibria, and the possible existence of a limit cycle is discussed. Numerical bifurcation analysis of the model is carried out to examine the impact of Allee effects as well as other key processes on trophic dynamics. Inclusion of Allee effects produces a richer array of dynamics than earlier models in which it was absent. When prey interacts with generalist predators, Allee effects operate synergistically to depress prey populations. Allee effects are more likely to depress occupancy levels when destruction of habitat patches is moderate; at severe levels of destruction, Allee effects are swamped by demographic effects of habitat loss. Stronger Allee effects correspond to lower thresholds of predator colonization rates at which prey become extinct. We discuss implications of our model for conservation of rare species as well as pest management via biocontrol. PMID:27543248

  16. Horned lizards (Phrynosoma) incapacitate dangerous ant prey with mucus.

    PubMed

    Sherbrooke, Wade C; Schwenk, Kurt

    2008-10-01

    Horned lizards (Iguanidae, Phrynosomatinae, Phrynosoma) are morphologically specialized reptiles characterized by squat, tank-like bodies, short limbs, blunt snouts, spines and cranial horns, among other traits. They are unusual among lizards in the degree to which they specialize on a diet of ants, but exceptional in the number of pugnacious, highly venomous, stinging ants they consume, especially harvester ants (genus Pogonomyrmex). Like other iguanian lizards, they capture insect prey on the tongue, but unlike other lizards, they neither bite nor chew dangerous prey before swallowing. Instead, they employ a unique kinematic pattern in which prey capture, transport and swallowing are combined. Nevertheless, horned lizards consume dozens of harvester ants without harm. We show that their derived feeding kinematics are associated with unique, mucus-secreting pharyngeal papillae that apparently serve to immobilize and incapacitate dangerous ants as they are swallowed by compacting them and binding them in mucus strands. Radially branched esophageal folds provide additional mucus-secreting surfaces the ants pass through as they are swallowed. Ants extracted from fresh-killed horned lizard stomachs are curled ventrally into balls and bound in mucus. We conclude that the pharyngeal papillae, in association with a unique form of hyolingual prey transport and swallowing, are horned lizard adaptations related to a diet of dangerous prey. Harvester ant defensive weapons, along with horned lizard adaptations against such weapons, suggest a long-term, predator-prey, co-evolutionary arms race between Phrynosoma and Pogonomyrmex.

  17. *A FASTER METHOD OF MEASURING RECREATIONAL WATER QUALITY FOR BETTER PROTECTION OF SWIMMER'S HEALTH

    EPA Science Inventory

    We previously reported that a faster method (< 2 hours) of measuring fecal indicator bacteria (FIB), based on Quantitative Polymerase Chain Reaction (QPCR), was predictive of swimming associated gastrointestinal illness. Using data from two additional beaches, we examined the re...

  18. Description of modular devices for the measurement of external dosimetry in radiation protection.

    PubMed

    Genicot, Jean Louis; Boogers, Eric; Van Iersel, Mark

    2015-04-01

    In 2002 the Group of Radiation Dosimetry and Calibration of the Belgian Nuclear Research Centre (SCK•CEN) has developed an experimental device based on the optically stimulated luminescence (OSL) working with Al2O3:C detectors (TLD-500 and Luxel) stimulated with an argon laser. A set of devices made from different modules have been developed to permit external dosimetry measurements with thermoluminescence (TL) and OSL techniques under different conditions. This study describes these measurement devices that can be made with these modules and some of the characteristics of the different systems. These devices present several advantages in terms of measurement possibilities: a small number of modules allow the use of different detection materials (Al2O3:C, BeO, quartz electronic components and tiles) and different measurement methods (TL, CW-OSL and pulsed OSL). Some applications are commented. PMID:25236335

  19. 49 CFR Appendix D to Part 192 - Criteria for Cathodic Protection and Determination of Measurements

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... into the structure surface as measured by an earth current technique applied at predetermined current... in sea water: −0.80 volt. C. In addition to the standard reference half cells, an alternate...

  20. Sensory challenges for trawling bats: Finding transient prey on water surfaces.

    PubMed

    Übernickel, Kirstin; Simon, Ralph; Kalko, Elisabeth K V; Tschapka, Marco

    2016-04-01

    Bats are able to identify obstacles and prey objects based exclusively on acoustic information acquired via echolocation. To assess the echo information potentially available to the trawling bat Noctilio leporinus, prey objects were ensonified with artificial bat calls and deduced echo target strengths (TS) of the reflected signals. The artificial calls consisted either of constant frequency (CF) or frequency modulated (FM) sounds. Detection distances were calculated for call intensities of N. leporinus emitted in the field and in confined space. Measurements of a transient target consisting of a brief water splash and subsequently expanding water ripples revealed that concentrically expanding water ripples can provide sufficiently loud echoes to be detected by trawling bats. Experiments with stationary targets revealed differences in TS depending on the type of signal used (CF or FM). A calculated maximum detection distance between 4.5 and 13.7 m for all measured targets indicates that prey detection in this very loud calling species occurs much earlier than suggested by estimations based on modifications in echolocation or flight behavior. PMID:27106338

  1. Predators choose prey over prey habitats: evidence from a lynx-hare system.

    PubMed

    Keim, Jonah L; DeWitt, Philip D; Lele, Subhash R

    2011-06-01

    Resource selection is grounded in the understanding that animals select resources based on fitness requirements. Despite uncertainty in how mechanisms relate to the landscape, resource selection studies often assume, but rarely demonstrate, a relationship between modeled variables and fitness mechanisms. Using Canada lynx (Lynx canadensis) and snowshoe hare (Lepus americanus) as a model system, we assess whether prey habitat is a viable surrogate for encounters between predators and prey. We simultaneously collected winter track data for lynx and hare in two study areas. We used information criteria to determine whether selection by lynx is best characterized by a hare resource selection probability function (RSPF) or by the amount of hare resource use. Results show that lynx selection is better explained by the amount of hare use (SIC = -21.9; Schwarz's Information Criterion) than by hare RSPF (SIC = -16.71), and that hare RSPF cannot be assumed to reveal the amount of resource use, a primary mechanism of predator selection. Our study reveals an obvious but important distinction between selection and use that is applicable to all resource selection studies. We recommend that resource selection studies be coupled with mechanistic data (e.g., metrics of diet, forage, fitness, or abundance) when investigating mechanisms of resource selection.

  2. Variable prey development time suppresses predator-prey cycles and enhances stability.

    PubMed

    Cronin, James T; Reeve, John D; Xu, Dashun; Xiao, Mingqing; Stevens, Heidi N

    2016-03-01

    Although theoretical models have demonstrated that predator-prey population dynamics can depend critically on age (stage) structure and the duration and variability in development times of different life stages, experimental support for this theory is non-existent. We conducted an experiment with a host-parasitoid system to test the prediction that increased variability in the development time of the vulnerable host stage can promote interaction stability. Host-parasitoid microcosms were subjected to two treatments: Normal and High variance in the duration of the vulnerable host stage. In control and Normal-variance microcosms, hosts and parasitoids exhibited distinct population cycles. In contrast, insect abundances were 18-24% less variable in High- than Normal-variance microcosms. More significantly, periodicity in host-parasitoid population dynamics disappeared in the High-variance microcosms. Simulation models confirmed that stability in High-variance microcosms was sufficient to prevent extinction. We conclude that developmental variability is critical to predator-prey population dynamics and could be exploited in pest-management programs.

  3. Reciprocity in predator-prey interactions: exposure to defended prey and predation risk affects intermediate predator life history and morphology.

    PubMed

    Hammill, Edd; Beckerman, Andrew P

    2010-05-01

    A vast body of literature exists documenting the morphological, behavioural and life history changes that predators induce in prey. However, little attention has been paid to how these induced changes feed back and affect the predators' life history and morphology. Larvae of the phantom midge Chaoborus flavicans are intermediate predators in a food web with Daphnia pulex as the basal resource and planktivorous fish as the top predator. C. flavicans prey on D. pulex and are themselves prey for fish; as D. pulex induce morphological defences in the presence of C. flavicans this is an ideal system in which to evaluate the effects of defended prey and top predators on an intermediate consumer. We assessed the impact on C. flavicans life history and morphology of foraging on defended prey while also being exposed to the non-lethal presence of a top fish predator. We tested the basic hypothesis that the effects of defended prey will depend on the presence or absence of top predator predation risk. Feeding rate was significantly reduced and time to pupation was significantly increased by defended morph prey. Gut size, development time, fecundity, egg size and reproductive effort respond to fish chemical cues directly or significantly alter the relationship between a trait and body size. We found no significant interactions between prey morph and the non-lethal presence of a top predator, suggesting that the effects of these two biological factors were additive or singularly independent. Overall it appears that C. flavicans is able to substantially modify several aspects of its biology, and while some changes appear mere consequences of resource limitation others appear facultative in nature. PMID:19936795

  4. Comparing nearshore benthic and pelagic prey as mercury sources to lake fish: the importance of prey quality and mercury content.

    PubMed

    Karimi, Roxanne; Chen, Celia Y; Folt, Carol L

    2016-09-15

    Mercury (Hg) bioaccumulation in fish poses well-known health risks to wildlife and humans through fish consumption. Yet fish Hg concentrations are highly variable, and key factors driving this variability remain unclear. One little studied source of variation is the influence of habitat-specific feeding on Hg accumulation in lake fish. However, this is likely important because most lake fish feed in multiple habitats during their lives, and the Hg and caloric content of prey from different habitats can differ. This study used a three-pronged approach to investigate the extent to which habitat-specific prey determine differences in Hg bioaccumulation in fish. This study first compared Hg concentrations in common nearshore benthic invertebrates and pelagic zooplankton across five lakes and over the summer season in one lake, and found that pelagic zooplankton generally had higher Hg concentrations than most benthic taxa across lakes, and over a season in one lake. Second, using a bioenergetics model, the effects of prey caloric content from habitat-specific diets on fish growth and Hg accumulation were calculated. This model predicted that the consumption of benthic prey results in lower fish Hg concentrations due to higher prey caloric content and growth dilution (high weight gain relative to Hg from food), in addition to lower prey Hg levels. Third, using data from the literature, links between fish Hg content and the degree of benthivory, were examined, and showed that benthivory was associated with reduced Hg concentrations in lake fish. Taken together, these findings support the hypothesis that higher Hg content and lower caloric content make pelagic zooplankton prey greater sources of Hg for fish than nearshore benthic prey in lakes. Hence, habitat-specific foraging is likely to be a strong driver of variation in Hg levels within and between fish species.

  5. Dynamics and patterns of a diffusive Leslie-Gower prey-predator model with strong Allee effect in prey

    NASA Astrophysics Data System (ADS)

    Ni, Wenjie; Wang, Mingxin

    2016-10-01

    This paper is devoted to study the dynamical properties and stationary patterns of a diffusive Leslie-Gower prey-predator model with strong Allee effect in the prey population. We first analyze the nonnegative constant equilibrium solutions and their stabilities, and then study the dynamical properties of time-dependent solutions. Moreover, we investigate the stationary patterns induced by diffusions (Turing pattern). Our results show that the impact of the strong Allee effect essentially increases the system spatiotemporal complexity.

  6. Protecting the autonomy of states to enact tobacco control measures under trade and investment agreements.

    PubMed

    Mitchell, Andrew; Sheargold, Elizabeth

    2015-06-01

    Since the adoption of the WHO's WHO Framework Convention on Tobacco Control, governments have been pursuing progressively stronger and more wide-reaching tobacco control measures. In response, tobacco companies are frequently using international trade and investment agreements as tools to challenge domestic tobacco control measures. Several significant new trade and investment agreements that some fear may provide new legal avenues to the tobacco industry to challenge health measures are currently under negotiation, including the Trans-Pacific Partnership (a 12 party agreement of Asia-Pacific regional countries) and the Transatlantic Trade and Investment Partnership (an agreement between the USA and the European Union). This commentary examines different options for treaty provisions that the parties could employ in these agreements to minimise legal risks relating to tobacco control measures. It recommends that parties take a comprehensive approach, combining provisions that minimise the potential costs of litigation with provisions that increase the likelihood of a state successfully defending tobacco control measures in such litigation.

  7. Protecting the autonomy of states to enact tobacco control measures under trade and investment agreements.

    PubMed

    Mitchell, Andrew; Sheargold, Elizabeth

    2015-06-01

    Since the adoption of the WHO's WHO Framework Convention on Tobacco Control, governments have been pursuing progressively stronger and more wide-reaching tobacco control measures. In response, tobacco companies are frequently using international trade and investment agreements as tools to challenge domestic tobacco control measures. Several significant new trade and investment agreements that some fear may provide new legal avenues to the tobacco industry to challenge health measures are currently under negotiation, including the Trans-Pacific Partnership (a 12 party agreement of Asia-Pacific regional countries) and the Transatlantic Trade and Investment Partnership (an agreement between the USA and the European Union). This commentary examines different options for treaty provisions that the parties could employ in these agreements to minimise legal risks relating to tobacco control measures. It recommends that parties take a comprehensive approach, combining provisions that minimise the potential costs of litigation with provisions that increase the likelihood of a state successfully defending tobacco control measures in such litigation. PMID:25361743

  8. Implementation of a complex of measures to fulfill the planetary protection requirements of the ExoMars-2016 mission

    NASA Astrophysics Data System (ADS)

    Khamidullina, Natalia; Novikova, Nataliya; Deshevaya, Elena; Orlov, Oleg; Guridov, Alexander; Zakharenko, Dmitry; Zaytseva, Olga

    2016-07-01

    The major purpose of the planetary protection program in the ExoMars-2016 mission is to forestall Mars contamination by terrestrial microorganisms. Since Martian descent module is not intended for biological experiments, ExoMars-2016 mission falls under COSPAR category IVa. Within the joint project co-sponsored by ESA and Roscosmos the European side holds full responsibility for ensuring a prescribed level of SC microbiological purity, while the Russian side is charged with compliance of the launch services provided on Baikonur technical complex with the planetary protection requirements that is, specifically, prevention of SC recontamination. To this end, a complex of measures was executed to control microbial contamination of cosmodrome facilities on the prescribed level which included: - regular decontamination of clean rooms using an effective disinfectant and impulse ultraviolet radiation that created favorable conditions for reliable functioning of the ESA clean tent, - replacement of airline filters in the Thermal Conditioning Unit (TCU) air duct for SC conditioning with pure air. The results of microbiological tests performed in the period of 2015 - 2016 lead to the conclusion that the Baikonur clean rooms (ISO class 8), TCU air ducts and Air Thermal Control System (ATCS) at launch site are ready for the launch campaign and that the Russian side fulfilled the planetary protection requirements of the ExoMars-2016 mission.

  9. Neuromuscular control of prey capture in frogs.

    PubMed Central

    Nishikawa, K C

    1999-01