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Sample records for burrowing crab neohelice

  1. Population structure of the burrowing crab Neohelice granulata (Brachyura, Varunidae in a southwestern Atlantic salt marsh

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    Sabrina Angeletti

    2015-07-01

    Full Text Available Neohelice granulata inhabits estuarine and protected coastal areas in temperate regions and is the most dominant decapod crustacean in the Bahía Blanca Estuary, Argentina. The population structure was studied during a year in a SW Atlantic salt marsh located in the Bahía Blanca Estuary. Crabs were sampled monthly from August 2010 to July 2011. The maximum observed density was 30 crabs m-2 in February and 70 burrows m-2 in May. The maximum carapace width (CW was 32 and 27.5 mm in males and females respectively. Medium size crabs were between 16 and 20 mm CW. Significantly smaller sized crabs were observed at the lower intertidal regions (P < 0.05. The sex ratio was favorable for males and was significantly different from the expected 1:1 (P < 0.05. The recruitment of unsexed juveniles crabs (CW <6.5 mm was observed throughout the year and the presence of ovigerous females from October to February indicated seasonal reproduction. The average size of ovigerous females was CW = 20.8 mm and the smallest ovigerous female measured was 16 mm CW. For the first time, the population structure of the most important macro-invertebrate is analyzed in the Bahía Blanca Estuary. This study may help to make decisions in the area, where anthropic action is progressing day by day.

  2. Population biology of the burrowing crab Neohelice granulata, (Crustacea: Decapoda: Varunidae from a tropical mangrove in Brazil

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    Rafael A. Gregati

    2009-03-01

    Full Text Available The population biology of the burrowing crab Neohelice granulata (Dana, 1851 from a mangrove in Jabaquara Beach, Paraty, state of Rio de Janeiro, Brazil (23º13'04"S and 44º42'47"W, was studied with respect to the following traits: size-frequency distribution, recruitment, reproductive period, fecundity, and sex ratio. Specimens were sampled monthly from April, 2003 to March, 2004, at the river margins during low tide periods. Size, sex, presence of eggs, and stage of the female gonad were recorded. Ovigerous females had their eggs removed and counted. The reproductive period was continuous and the highest frequency of ovigerous females was recorded in the fall and winter. Mature gonads were found throughout the year and recruitment was continuous but more intense during the summer. The fecundity of N. granulata (30028.3 ± 10861.2 eggs was high in comparison to studies in other localities. In general, the proportion of males was similar to that of females (1:0.92; however, males were predominant in the fall (1:0.77 and winter (1:0.75. All the information available so far on the reproduction of N. granulata involves populations from subtropical salt marshes; therefore, comparative studies including other habitats, such as mangrove forests, are needed to further understand the environmental influences on the population and reproductive biology of semiterrestrial crabs.

  3. The crab Neohelice (= Chasmagnathus) granulata: an emergent animal model from emergent countries

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    Spivak, Eduardo D.

    2010-09-01

    Neohelice granulata (previously known as Chasmagnathus granulata and C. granulatus) is a burrowing semiterrestrial crab found in the intertidal zone of estuaries, salt marshes and mangroves of the South-western Atlantic Ocean. Beginning in the late 1989s, an explosion of publications appeared in international journals dealing with its ecology, physiology, toxicology and behavior. A bibliometric analysis using the Scopus database allowed detecting 309 papers that deal with this species during the period 1986-2009. The number of papers per year increased continuously, reaching a mean annual value of 22.6 during the last 5 years; a great majority of them were authored by researchers from Argentina and Brazil. Neohelice granulata has become now one of the most studied crab species, after Carcinus maenas, Callinectes sapidus, Scylla serrata and Cancer pagurus and C. magister, and it can be considered as an emergent animal model for biochemical, physiological and ecological research.

  4. Biochemical and physiological adaptations in the estuarine crab Neohelice granulata during salinity acclimation.

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    Bianchini, Adalto; Lauer, Mariana Machado; Nery, Luiz Eduardo Maia; Colares, Elton Pinto; Monserrat, José María; Dos Santos Filho, Euclydes Antônio

    2008-11-01

    Neohelice granulata (Chasmagnathus granulatus) is an intertidal crab species living in salt marshes from estuaries and lagoons along the Atlantic coast of South America. It is a key species in these environments because it is responsible for energy transfer from producers to consumers. In order to deal with the extremely marked environmental salinity changes occurring in salt marshes, N. granulata shows important and interesting structural, biochemical, and physiological adaptations at the gills level. These adaptations characterize this crab as a euryhaline species, tolerating environmental salinities ranging from very diluted media to concentrated seawater. These characteristics had led to its use as an animal model to study estuarine adaptations in crustaceans. Therefore, the present review focuses on the influence of environmental salinity on N. granulata responses at the ecological, organismic and molecular levels. Aspects covered include salinity tolerance, osmo- and ionoregulatory patterns, morphological and structural adaptations at the gills, and mechanisms of ion transport and their regulation at the gills level during environmental salinity acclimation. Finally, this review compiles information on the effects of some environmental pollutants on iono- and osmoregulatory adaptations showed by N. granulata.

  5. Larval dispersion of the estuarine crab Neohelice granulata in coastal marine waters of the Southwest Atlantic

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    Bas, Claudia; Luppi, Tomás; Spivak, Eduardo; Schejter, Laura

    2009-08-01

    The estuarine brachyuran crab Neohelice granulata export their larvae from the parental intertidal population of the Mar Chiquita coastal lagoon, and probably other populations, to marine waters. The degree of larval dispersion or self-recruitment of populations is unknown. We evaluated the presence of all larval stages of N. granulata in coastal waters of Argentina between 37.9° and 35.8° S, at two different spatial scales: a broad scale of tens to hundreds of kilometers from the Río de la Plata estuary in the north, to Mar Chiquita lagoon in the south, and a small scale of hundreds of meters to some kilometers around the mouth of Mar Chiquita, during spring and summer. Additionally, we registered the larval composition and density at San Clemente creek population, in Samborombon Bay (Río de la Plata estuary), every 3 h along a 30-hour period. Evidence indicates that larval release of N. granulata is temporally synchronized with nocturnal ebb tides and all development from Zoea I to Zoea IV occur in areas close to the parental population, even with very different oceanographic characteristics. A possible mechanism based on salinity selection and wind-driven transport is proposed for such behavior, and some considerations related to the connectivity of present populations are made.

  6. Surface expression of NMDA receptor changes during memory consolidation in the crab Neohelice granulata

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    Hepp, Yanil; Salles, Angeles; Carbo-Tano, Martin

    2016-01-01

    The aim of the present study was to analyze the surface expression of the NMDA-like receptors during the consolidation of contextual learning in the crab Neohelice granulata. Memory storage is based on alterations in the strength of synaptic connections between neurons. The glutamatergic synapses undergo various forms of N-methyl-D aspartate receptor (NMDAR)-dependent changes in strength, a process that affects the abundance of other receptors at the synapse and underlies some forms of learning and memory. Here we propose a direct regulation of the NMDAR. Changes in NMDAR's functionality might be induced by the modification of the subunit's expression or cellular trafficking. This trafficking does not only include NMDAR's movement between synaptic and extra-synaptic localizations but also the cycling between intracellular compartments and the plasma membrane, a process called surface expression. Consolidation of contextual learning affects the surface expression of the receptor without affecting its general expression. The surface expression of the GluN1 subunit of the NMDAR is down-regulated immediately after training, up-regulated 3 h after training and returns to naïve and control levels 24 h after training. The changes in NMDAR surface expression observed in the central brain are not seen in the thoracic ganglion. A similar increment in surface expression of GluN1 in the central brain is observed 3 h after administration of the competitive GABAA receptor antagonist, bicuculline. These consolidation changes are part of a plasticity event that first, during the down-regulation, stabilizes the trace and later, at 3-h post-training, changes the threshold for synapse activation. PMID:27421895

  7. Artificial Crab Burrows Facilitate Desalting of Rooted Mangrove Sediment in a Microcosm Study

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    Nathalie Pülmanns

    2015-07-01

    Full Text Available Water uptake by mangrove trees can result in salt accumulation in sediment around roots, negatively influencing growth. Tidal pumping facilitates salt release and can be enhanced by crab burrows. Similarly, flushing of burrows by incoming tidal water decreases sediment salinity. In contrast to burrows with multiple entrances, the role of burrows with one opening for salinity reduction is largely unknown. In a microcosm experiment we studied the effect of artificial, burrow-like macro-pores with one opening on the desalting of mangrove sediment and growth of Rhizophora mangle L. seedlings. Sediment salinity, seedling leaf area and seedling growth were monitored over six months. Artificial burrows facilitated salt release from the sediment after six weeks, but seedling growth was not influenced. To test whether crab burrows with one opening facilitate salt release in mangrove forests, sediment salinities were measured in areas with and without R. mangle stilt roots in North Brazil at the beginning and end of the wet season. In addition, burrows of Ucides cordatus were counted. High crab burrow densities and sediment salinities were associated with stilt root occurrence. Precipitation and salt accumulation by tree roots seem to have a larger effect on sediment salinity than desalting by U. cordatus burrows.

  8. Hatching and larval export of the intertidal crab Neohelice granulata in Mar Chiquita coastal lagoon, Argentina

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    Guillermina Sánchez Vuichard

    2013-06-01

    Full Text Available Synchronization in the events of the reproductive cycle in female Neohelice granulata Dana, 1851 were studied from samples taken weekly and biweekly from September to December 2006 in the Laguna Mar Chiquita. The timing and larval hatching and synchronicity were inferred from numbers of ovigerous females and observing the stages of embryonic development. Synchronization in larval hatching also was observed in females in experiments in dark for a period of 48 hours, at three different salinities (10, 23 and 33 ppm. In addition plankton sampling were performed in order to study larval exportation at the field and its link to the tidal and light/dark cycles. We found that ovigerous females of N. granulata have a marked synchronization in embryonic development which results in that most of berried females are close to hatching within a period of maximum tidal range (days. Within this period, there is a synchronization of hatching at a time scale of hours, governed by environmental conditions. The salinity range used in this study (10-32‰ did not affect hatching synchronicity neither time to hatch. Hatching was synchronized according to endogenous rhythms governed mainly by the tidal cycle and secondarily by the breadth of it. It is also conditioned by the light-dark cycle through an exogenous cycle, so that the hatchings would occur mostly at night high tides.

  9. Effect of mangrove restoration on crab burrow density in Luoyangjiang Estuary, China

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    Wei Li

    2015-07-01

    Full Text Available Background Mangrove restoration seeks to restore or rebuild degraded mangrove systems. The methods of mangrove restoration include ecological projects and restoration-oriented technologies, the latter of which are designed to restore the structure, processes as well as related physical, chemical and biological characteristics of wetlands and to ensure the provision of ecosystem services. As important components of mangrove ecosystem, benthic organisms and crabs play a key role in nutrient cycling. In addition, mangrove restoration, such as vegetation restoration measures, can lead to changes in the benthic faunal communities. This study investigates whether the presence of different mangrove species, age and canopy cover of mangrove communities affect the density of crab burrows. Methods The Luoyangjiang Estuary, in the southeast of Fujian Province, was selected as our research area. A survey, covering 14 sites, was conducted to investigate the impacts of mangrove restoration on the density of crab burrows in four rehabilitated forests with different stand ages and canopy. Results It was found that differences in vegetation types had a large impact on crab density and that the density of crab burrows was lower on exposed beaches (non-mangrove than under mature Kandelia candel, Aegiceras corniculatum and Avicennia marina communities. In general, the amount of leaf litter and debris on mangrove mudflats was greater than on the beaches as food sources for crabs. Two-factor analysis of variance (ANOVA shows that changes in mangrove species and age since restoration had different effects on crab burrow density. The effect of canopy cover was highly significant on crab burrow density. Conclusions The results suggest that in the process of mangrove restoration the combined effects of mangrove stand age, canopy cover and other factors should be taken into account. This study further supports the findings of the future scientific research and practice on

  10. Air exposure behavior of the semiterrestrial crab Neohelice granulata allows tolerance to severe hypoxia but not prevent oxidative damage due to hypoxia-reoxygenation cycle.

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    de Lima, Tábata Martins; Geihs, Márcio Alberto; Nery, Luiz Eduardo Maia; Maciel, Fábio Everton

    2015-11-01

    The air exposure behavior of the semi-terrestrial crab Neohelice granulata during severe hypoxia was studied. This study also verified whether this behavior mitigates possible oxidative damage, namely lipoperoxidation, caused by hypoxia and reoxygenation cycles. The lethal time for 50% of the crabs subjected to severe hypoxia (0.5 mgO2 · L(-1)) with free access to air was compared to that of crabs subjected to severe hypoxia without access to air. Crabs were placed in aquaria divided into three zones: water (when the animal was fully submersed), land (when the animal was completely emerged) and intermediate (when the animal was in contact with both environments) zones. Then the crabs were held in this condition for 270 min, and the time spent in each zone was recorded. Lipid peroxidation (LPO) damage to the walking leg muscles was determined for the following four experimental conditions: a--normoxic water with free access to air; b--hypoxic water without access to air; c--hypoxic water followed by normoxic water without air access; and d--hypoxic water with free access to air. When exposed to hypoxic water, N. granulata spent significantly more time on land, 135.3 ± 17.7 min, whereas control animals (exposed to normoxic water) spent more time submerged, 187.4 ± 20.2 min. By this behavior, N. granulata was able to maintain a 100% survival rate when exposed to severe hypoxia. However, N. granulata must still return to water after periods of air exposure (~ 14 min), causing a sequence of hypoxia/reoxygenation events. Despite increasing the survival rate, hypoxia with air access does not decrease the lipid peroxidation damage caused by the hypoxia and reoxygenation cycle experienced by these crabs.

  11. The vibrational signals that male fiddler crabs ( Uca lactea) use to attract females into their burrows

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    Takeshita, Fumio; Murai, Minoru

    2016-06-01

    In some fiddler crab species, males emit vibrations from their burrows to mate-searching females after they have attracted a female to the burrow entrance using a waving display. Although the vibrations are considered acoustic signals to induce mating, it has not been demonstrated whether the vibrations attract the females into the burrow and, consequently, influence females' mating decisions. We investigated the structures and patterns of the vibrations using a dummy female and demonstrated experimentally a female preference for male vibrations in Uca lactea in the field. The acoustic signals consisted of repetitions of pulses. The dominant frequency of the pulses decreased with male carapace width. The pulse length decreased slightly with an increasing number of vibrational repetitions, and the pulse interval increased with increasing repetitions. These factors imply that the vibrations convey information on male characteristics, such as body size and stamina. In the experiment on female mate choice, the females significantly preferred males with higher pulse repetition rates when they were positioned at the entrance of the burrow, indicating that the females use the male vibrational signals to decide whether to enter the burrow. However, females showed no preference for the vibrations once they were inside a burrow, i.e., whether they decided to copulate, suggesting that the vibrations do not independently affect a female's final decision of mate choice. The vibrations inside the burrow might influence a female's decision by interaction with other male traits such as the burrow structure.

  12. Nitric oxide-dependent pigment migration induced by ultraviolet radiation in retinal pigment cells of the crab Neohelice granulata.

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    Filgueira, Daza de Moraes Vaz Batista; Guterres, Laís Pereira; Votto, Ana Paula de Souza; Vargas, Marcelo Alves; Boyle, Robert Tew; Trindade, Gilma Santos; Nery, Luiz Eduardo Maia

    2010-01-01

    The purpose of this study was to verify the occurrence of pigment dispersion in retinal pigment cells exposed to UVA and UVB radiation, and to investigate the possible participation of a nitric oxide (NO) pathway. Retinal pigment cells from Neohelice granulata were obtained by cellular dissociation. Cells were analyzed for 30 min in the dark (control) and then exposed to 1.1 and 3.3 J cm(-2) UVA, 0.07 and 0.9 J cm(-2) UVB, 20 nmβ-PDH (pigment dispersing hormone) or 10 μm SIN-1 (NO donor). Histological analyses were performed to verify the UV effect in vivo. Cultured cells were exposed to 250 μm L-NAME (NO synthase blocker) and afterwards were treated with UVA, UVB or β-PDH. The retinal cells in culture displayed significant pigment dispersion in response to UVA, UVB and β-PDH. The same responses to UVA and UVB were observed in vivo. SIN-1 did not induce pigment dispersion in the cell cultures. L-NAME significantly decreased the pigment dispersion induced by UVA and UVB but not by β-PDH. All retinal cells showed an immunopositive reaction against neuronal nitric oxide synthases. Therefore, UVA and UVB radiation are capable of inducing pigment dispersion in retinal pigment cells of Neohelice granulata and this dispersion may be nitric oxide synthase dependent. © 2010 The Authors. Journal Compilation. The American Society of Photobiology.

  13. Larval salinity tolerance of the South American salt-marsh crab, Neohelice (Chasmagnathus) granulata: physiological constraints to estuarine retention, export and reimmigration

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    Anger, Klaus; Spivak, Eduardo; Luppi, Tomás; Bas, Claudia; Ismael, Deborah

    2008-06-01

    The semiterrestrial crab Neohelice (= Chasmagnathus) granulata (Dana 1851) is a predominant species in brackish salt marshes, mangroves and estuaries. Its larvae are exported towards coastal marine waters. In order to estimate the limits of salinity tolerance constraining larval retention in estuarine habitats, we exposed in laboratory experiments freshly hatched zoeae to six different salinities (5 32‰). At 5‰, the larvae survived for a maximum of 2 weeks, reaching only exceptionally the second zoeal stage, while 38% survived to the megalopa stage at 10‰. Shortest development and negligible mortality occurred at all higher salt concentrations. These observations show that the larvae of N. granulata can tolerate a retention in the mesohaline reaches of estuaries, with a lower limit of ca. 10 15‰. Maximum survival at 25‰ suggests that polyhaline conditions rather than an export to oceanic waters are optimal for successful larval development of this species. In another experiment, we tested the capability of the last zoeal stage (IV) for reimmigration from coastal marine into brackish waters. Stepwise reductions of salinity during this stage allowed for moulting to the megalopa at 4 10‰. Although survival was at these conditions reduced and development delayed, these results suggest that already the zoea-IV stage is able to initiate the reimmigration into estuaries. After further salinity reduction, megalopae survived in this experiment for up to >3 weeks in freshwater, without moulting to juvenile crabs. In a similar experiment starting from the megalopa stage, successful metamorphosis occurred at 4 10‰, and juvenile growth continued in freshwater. Although these juvenile crabs showed significantly enhanced mortality and smaller carapace width compared to a seawater control, our results show that the late larval and early juvenile stages of N. granulata are well adapted for successful recruitment in brackish and even limnetic habitats.

  14. BURROW ARCHITECTURE OF RED GHOST CRAB OCYPODE MACROCERA (H. MILNE-EDWARDS, 1852) : A CASE STUDY IN INDIAN SUNDARBANS

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    Sourabh Kumar Dubey; Deep Chandan Chakraborty; Sudipta Chakraborty; Amalesh Choudhury

    2013-01-01

    A study on burrow architecture and burrow morphology of the red ghost crab (Ocypode macrocera) was carried out at the southern proximity of the Sagar island (21°37.973' N, to E 88° 04.195'), western sector of Indian Sundarbans that faces the regular tidal influences of Bay of Bengal. Ocypode macrocera constructs burrows that are highly species specific and used by single individual. Four types of burrow patterns were observed like ‘I’, ‘J’ ‘U’ and ‘semi-U’ type with different size...

  15. Like night and day: Reversals of thermal gradients across ghost crab burrows and their implications for thermal ecology

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    Watson, Gregory S.; Gregory, Emily A.; Johnstone, Charmaine; Berlino, Manuel; Green, David W.; Peterson, Nicola R.; Schoeman, David S.; Watson, Jolanta A.

    2018-04-01

    Ghost crabs, Ocypode cordimanus, inhabit relatively hostile environments subject to thermal fluctuations, including both diurnal and seasonal cycles. For many ectotherms, including ghost crabs, a major challenge is to remain cool during hot daytime temperatures. This can be achieved by adopting a fossorial lifestyle, taking advantage of thermal refuge afforded by burrows of sufficient depth. Another consideration, often overlooked, is the potential advantage associated with ready access to a thermal energy source (a "charging station") when surface temperatures are cooler. Being able to rapidly elevate body temperature during cool periods would enhance the crab's ability to maintain rate processes and carry out essential activities. We have measured ghost crab burrow temperature profiles at two times of the day with contrasting sun exposure (06:00 and 14:00), demonstrating how effective burrow depth (up to a maximum of 40 cm) provides thermal regulation below the surface of the sand (e.g., at dawn (06:00) and early afternoon (14:00) at a depth of 5 cm, temperatures (±SD) of 16.32 ± 0.96 °C and 25.04 ± 1.47 °C were recorded, respectively. Corresponding temperatures at a depth of 30 cm were 19.17 ± 0.59 °C and 19.78 ± 1.60 °C, respectively). This demonstrates that while temperature conditions at the surface vary dramatically from night to day, ghost crab burrows can maintain relatively constant temperatures at the burrow base throughout the diurnal cycle, at least during winter. As a consequence, the burrow heat signatures undergo a corresponding thermal gradient reversal between night and day, as revealed by infra-red photography. Complementing these field observations, we also determined heating and cooling times/constants for O. cordimanus in the laboratory (τ = 17.54 and 16.59 JK-1, respectively), and analysed chemical composition of their carapace (external (with β Chitin evident) and internal (predominance of α Chitin)), which is the primary thermal

  16. Burrows of the semi-terrestrial crab Ucides cordatus enhance CO2 release in a North Brazilian mangrove forest.

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    Nathalie Pülmanns

    Full Text Available Ucides cordatus is an abundant mangrove crab in Brazil constructing burrows of up to 2 m depth. Sediment around burrows may oxidize during low tides. This increase in sediment-air contact area may enhance carbon degradation processes. We hypothesized that 1 the sediment CO2 efflux rate is greater with burrows than without and 2 the reduction potential in radial profiles in the sediment surrounding the burrows decreases gradually, until approximating non-bioturbated conditions. Sampling was conducted during the North Brazilian wet season at neap tides. CO2 efflux rates of inhabited burrows and plain sediment were measured with a CO2/H2O gas analyzer connected to a respiration chamber. Sediment redox potential, pH and temperature were measured in the sediment surrounding the burrows at horizontal distances of 2, 5, 8 and 15 cm at four sediment depths (1, 10, 30 and 50 cm and rH values were calculated. Sediment cores (50 cm length were taken to measure the same parameters for plain sediment. CO2 efflux rates of plain sediment and individual crab burrows with entrance diameters of 7 cm were 0.7-1.3 µmol m(-2 s(-1 and 0.2-0.4 µmol burrows(-1 s(-1, respectively. CO2 released from a Rhizophora mangle dominated forest with an average of 1.7 U. cordatus burrows(-1 m(-2 yielded 1.0-1.7 µmol m(-2 s(-1, depending on the month and burrow entrance diameter. Laboratory experiments revealed that 20-60% of the CO2 released by burrows originated from crab respiration. Temporal changes in the reduction potential in the sediment surrounding the burrows did not influence the CO2 release from burrows. More oxidized conditions of plain sediment over time may explain the increase in CO2 release until the end of the wet season. CO2 released by U. cordatus and their burrows may be a significant pathway of CO2 export from mangrove sediments and should be considered in mangrove carbon budget estimates.

  17. Burrows of the semi-terrestrial crab Ucides cordatus enhance CO2 release in a North Brazilian mangrove forest.

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    Pülmanns, Nathalie; Diele, Karen; Mehlig, Ulf; Nordhaus, Inga

    2014-01-01

    Ucides cordatus is an abundant mangrove crab in Brazil constructing burrows of up to 2 m depth. Sediment around burrows may oxidize during low tides. This increase in sediment-air contact area may enhance carbon degradation processes. We hypothesized that 1) the sediment CO2 efflux rate is greater with burrows than without and 2) the reduction potential in radial profiles in the sediment surrounding the burrows decreases gradually, until approximating non-bioturbated conditions. Sampling was conducted during the North Brazilian wet season at neap tides. CO2 efflux rates of inhabited burrows and plain sediment were measured with a CO2/H2O gas analyzer connected to a respiration chamber. Sediment redox potential, pH and temperature were measured in the sediment surrounding the burrows at horizontal distances of 2, 5, 8 and 15 cm at four sediment depths (1, 10, 30 and 50 cm) and rH values were calculated. Sediment cores (50 cm length) were taken to measure the same parameters for plain sediment. CO2 efflux rates of plain sediment and individual crab burrows with entrance diameters of 7 cm were 0.7-1.3 µmol m(-2) s(-1) and 0.2-0.4 µmol burrows(-1) s(-1), respectively. CO2 released from a Rhizophora mangle dominated forest with an average of 1.7 U. cordatus burrows(-1) m(-2) yielded 1.0-1.7 µmol m(-2) s(-1), depending on the month and burrow entrance diameter. Laboratory experiments revealed that 20-60% of the CO2 released by burrows originated from crab respiration. Temporal changes in the reduction potential in the sediment surrounding the burrows did not influence the CO2 release from burrows. More oxidized conditions of plain sediment over time may explain the increase in CO2 release until the end of the wet season. CO2 released by U. cordatus and their burrows may be a significant pathway of CO2 export from mangrove sediments and should be considered in mangrove carbon budget estimates.

  18. BURROW ARCHITECTURE OF RED GHOST CRAB OCYPODE MACROCERA (H. MILNE-EDWARDS, 1852 : A CASE STUDY IN INDIAN SUNDARBANS

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    Sourabh Kumar Dubey

    2013-12-01

    Full Text Available A study on burrow architecture and burrow morphology of the red ghost crab (Ocypode macrocera was carried out at the southern proximity of the Sagar island (21°37.973' N, to E 88° 04.195', western sector of Indian Sundarbans that faces the regular tidal influences of Bay of Bengal. Ocypode macrocera constructs burrows that are highly species specific and used by single individual. Four types of burrow patterns were observed like ‘I’, ‘J’ ‘U’ and ‘semi-U’ type with different sizes as revealed by POP casting. Important physic-chemical parameters like air temperature, temperature and salinity of the water were significantly varied (P < 0.05 throughout seasons in the Ocypode zone. Burrow sand column temperature were also significantly varied from ambient air temperature thus exhibiting preference for cooler subterranean residential compartment. The digging behaviour of Ocypodes enhances oxygenation in the ground soil and facilitates decomposition of organic materials, nutrient recycling, entrapping the sediments and mangrove seedlings and helps the process of bioturbation. As per the preliminary observations it was suggested that burrow shape is directly related to tidal action and metabolic activities of the crab are strongly correlated with burrow microenvironment. They are adapted to the different sediment conditions, tidal fluctuations, varying salinity gradients, air and water temperatures and other environmental fluctuations.

  19. Burrows of the Semi-Terrestrial Crab Ucides cordatus Enhance CO2 Release in a North Brazilian Mangrove Forest

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    Pülmanns, Nathalie; Diele, Karen; Mehlig, Ulf; Nordhaus, Inga

    2014-01-01

    Ucides cordatus is an abundant mangrove crab in Brazil constructing burrows of up to 2 m depth. Sediment around burrows may oxidize during low tides. This increase in sediment-air contact area may enhance carbon degradation processes. We hypothesized that 1) the sediment CO2 efflux rate is greater with burrows than without and 2) the reduction potential in radial profiles in the sediment surrounding the burrows decreases gradually, until approximating non-bioturbated conditions. Sampling was conducted during the North Brazilian wet season at neap tides. CO2 efflux rates of inhabited burrows and plain sediment were measured with a CO2/H2O gas analyzer connected to a respiration chamber. Sediment redox potential, pH and temperature were measured in the sediment surrounding the burrows at horizontal distances of 2, 5, 8 and 15 cm at four sediment depths (1, 10, 30 and 50 cm) and rH values were calculated. Sediment cores (50 cm length) were taken to measure the same parameters for plain sediment. CO2 efflux rates of plain sediment and individual crab burrows with entrance diameters of 7 cm were 0.7–1.3 µmol m−2 s−1 and 0.2–0.4 µmol burrows−1 s−1, respectively. CO2 released from a Rhizophora mangle dominated forest with an average of 1.7 U. cordatus burrows−1 m−2 yielded 1.0–1.7 µmol m−2 s−1, depending on the month and burrow entrance diameter. Laboratory experiments revealed that 20–60% of the CO2 released by burrows originated from crab respiration. Temporal changes in the reduction potential in the sediment surrounding the burrows did not influence the CO2 release from burrows. More oxidized conditions of plain sediment over time may explain the increase in CO2 release until the end of the wet season. CO2 released by U. cordatus and their burrows may be a significant pathway of CO2 export from mangrove sediments and should be considered in mangrove carbon budget estimates. PMID:25313661

  20. Effects of the burrowing crab Chasmagnathus granulata (Dana on meiofauna of estuarine intertidal habitats of Patos Lagoon, Southern Brazil

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    Leonardo Cruz Rosa

    2005-03-01

    Full Text Available This study aimed to evaluate the effects of the burrowing crab Chasmagnathus granulata on meiofauna at three intertidal habitats across a tidal exposure gradient (i.e., an emerged salt marsh, an emerged mudflat and a submerged mudflat in an estuarine embayment of Patos Lagoon, Southern Brazil. Meiofauna community was dominated by nematodes and ostracods, following by copepods and turbellarians. Densities of all studied organisms varied significantly among habitats. Highest values were observed in submerged mudflat while lower in salt marsh. Nematodes were unaffected by crab in either habitat, whereas ostracod, copepod and turbellarian densities were significantly lower in disturbed than control areas in both mudflat habitats. Any meiofaunal group was affected in salt marsh, probably due to a less intense disturbance. The results showed that the burrowing crab C. granulata could play an important role on meiofauna community structure in estuarine intertidal habitats of Patos Lagoon, because crab disturbance seemed to affect mainly surface populations, especially in mudflat. However, the meiofauna response to crab disturbance was variable among habitats depending of the intensity and the frequency of the disturbance.Este trabalho avalia os efeitos do caranguejo Chasmagnathus granulata sobre a meiofauna em três ambientes intermareais, durante um prolongado período de exposição (uma marisma emersa, um plano de lama emerso e outro submerso, numa enseada estuarina da Lagoa dos Patos. Nematódeos e ostrácodes foram os organismos dominantes, seguidos por copépodes e turbelários. As densidades dos organismos variam significativamente entre os hábitats. As maiores densidades foram registradas no plano de lama submerso e as menores na marisma. Os nematódeos não foram afetados pelo caranguejo em nenhum hábitat. As densidades dos ostrácodes, copépodes e turbelários foram significativamente menores nos sedimentos perturbados do que nas

  1. Biochemical characteristics and modulation by external and internal factors of aminopeptidase-N activity in the hepatopancreas of a euryhaline burrowing crab.

    Science.gov (United States)

    Michiels, M S; del Valle, J C; López Mañanes, A A

    2015-07-01

    Strikingly, in spite of its physiological importance, information about occurrence, biochemical characteristics and mechanisms of regulation of aminopeptidase-N (APN) in the hepatopancreas of intertidal euryhaline crabs is still lacking. In this work, we determined the occurrence, biochemical characteristics, response to environmental salinity and dopamine of APN in the hepatopancreas of the euryhaline crab Neohelice granulata (Dana 1851) from the open mudflat of Mar Chiquita coastal lagoon (Buenos Aires province, Argentina). APN activity was maximal at pH and temperature range of 7.6-9.0 and 37-45 °C, respectively. APN activity exhibited Michaelis-Menten kinetics (apparent Km = 0.19 ± 0.10 mM) (pH 7.6, 37 °C) and appeared to be sensitive to bestatin (I 50 = 15 mM) and EDTA (I 50 = 9 mM). In crabs acclimated to 10 psu (hyper-regulation conditions) and 37 psu (hypo-regulation conditions), APN activity was about 45 and 160% higher, respectively, than in 35 psu (osmoconformation). APN activity in the hepatopancreas was stimulated in vitro (about 137%) by 10(-4) M dopamine. Higher dopamine concentrations produced a similar extent of increase. The responses of APN activity to salinity and dopamine in vitro suggest the role of APN in digestive adjustments upon hyper and hypo-regulatory conditions and its modulation via direct mechanisms on hepatopancreas by dopamine.

  2. Selective geochemistry of iron in mangrove soils in a semiarid tropical climate: effects of the burrowing activity of the crabs Ucides cordatus and Uca maracoani

    Science.gov (United States)

    Araújo, J. M. C.; Otero, X. L.; Marques, A. G. B.; Nóbrega, G. N.; Silva, J. R. F.; Ferreira, T. O.

    2012-08-01

    Bioturbation by crabs may affect processes associated with organic matter decomposition in mangrove soils. This study examines how two crabs ( Uca maracoani and Ucides cordatus), which are of substantial ecological and economic importance in semiarid coastal areas of Brazil, affect biogeochemical processes in mangrove soils. For this purpose, the physicochemical and geochemical parameters of the soils at different sites were analyzed. The redox potential was always positive at bioturbated sites (+12 to +218 mV), indicating more oxidizing conditions conducive to the oxidation of pyrite and precipitation of oxyhydroxides. In contrast, anoxic conditions prevailed at the control site (Eh mangrove soils, being capable of enhancing organic matter decomposition and also shifting the dominant pathway of organic matter degradation.

  3. The ecology of fiddler crab Uca forcipata in mangrove forest

    Science.gov (United States)

    Mokhtari, Mohammad; Ghaffar, Mazlan Abd; Usup, Gires; Cob, Zaidi Che

    2013-11-01

    Fiddler crab burrows increase oxygen dispersion in anoxic mangrove sediment and promote iron reduction and nitrification process over sulfate reduction in subsurface sediment. Therefore it is expected to accelerate decomposition rate under oxic and suboxic conditions. In this study the effect of environmental parameters on the local distribution of U. forcipata and subsequently the effect of crab burrows on sediment characteristics were investigated. Our result indicated that U. forcipata prefers to live in the open mudflats under the shade of mangrove trees. The most important factors determining their presence were sediment texture, porosity, organic content, water content, carbon content and temperature. Measurement of redox potential and iron pools clearly indicated a distinct oxidized layer around burrows although sediment porosity, organic and water content did not differ significantly between burrowed and non-burrowed mudflats and even among the burrow profiles. This result implies the oxidation created by burrowing activity of U .forcipata was not efficient to change physical properties of mangrove sediments.

  4. Good Crab, Bad Crab

    Science.gov (United States)

    Are crabs friends or foes of marsh grass, benefit or detriment to the salt marsh system? We examined Uca pugilator (sand fiddler) and Sesarma reticulatum (purple marsh crab) with Spartina patens (salt marsh hay) at two elevations (10 cm below MHW and 10 cm above MHW) in mesocosms...

  5. Simulating cryptic movements of a mangrove crab : Recovery phenomena after small scale fishery

    NARCIS (Netherlands)

    Piou, C.; Berger, U.; Hildenbrandt, H.; Grimm, V.; Diele, K.; D'Lima, C.

    2007-01-01

    The semi-terrestrial burrowing crab Ucides cordatus is an important ecological component and economic resource of Brazilian mangrove forests. The crab population of the Caete peninsula (the location of our study site) has been exploited for the last 40 years. Recovery of fished areas by crabs from

  6. Evidence of marine debris usage by the ghost crab Ocypode quadrata (Fabricius, 1787).

    Science.gov (United States)

    Costa, Leonardo Lopes; Rangel, Danilo Freitas; Zalmon, Ilana Rosental

    2018-03-01

    Sandy beaches are sites of marine debris stranding, but the interaction of beach biota with waste is poorly studied. The objective of this study was to investigate whether the ghost crab Ocypode quadrata selects marine debris by types using a non-destructive method on sandy beaches of Southeastern Brazil. We found marine debris in 7% of 1696 surveyed burrows, and the ghost crabs selectivity was mainly by soft plastic (30%), straw (11%), rope (6%) and foam (4%). Burrows with marine debris showed higher occupation rate (~68%) compared to burrows without debris (~28%), indicating that these materials may increase the capacity of ghost crabs to memorize their burrows placement (homing). The percentage of marine debris was not always related to their amount in the drift line, but ghost crabs used more debris near urbanized areas. Future studies should test whether ghost crabs are using marine debris for feeding, homing or other mechanisms. Copyright © 2018 Elsevier Ltd. All rights reserved.

  7. Dry season distribution of land crabs, Gecarcinus quadratus (Crustacea: Gecarcinidae), in Corcovado National Park, Costa Rica.

    Science.gov (United States)

    Griffiths, Megan E; Mohammad, Basma A; Vega, Andres

    2007-03-01

    The land crab Gecarcinus quadratus is an engineering species that controls nutrient cycling in tropical forests. Factors regulating their coastal distribution are not fully understood. We quantified land crab distribution during the dry season at Sirena Field Station in Corcovado National Park, Costa Rica, and found that land crab burrow density decreases with increasing distance from the ocean. Leaf litter depth and tree seedling density are negatively correlated with land crab burrow density. Burrows are strongly associated with sand substrate and burrow density is comparatively low in clay substrate. Results suggest that G. quadratus is limited to a narrow coastal zone with sand substrate, and this distribution could have profound effects on plant community structure.

  8. Land crabs as key drivers in tropical coastal forest recruitment

    Science.gov (United States)

    Lindquist, E.S.; Krauss, K.W.; Green, P.T.; O'Dowd, D. J.; Sherman, P.M.; Smith, T. J.

    2009-01-01

    Plant populations are regulated by a diverse assortment of abiotic and biotic factors that influence seed dispersal and viability, and seedling establishment and growth at the microsite. Rarely does one animal guild exert as significant an influence on different plant assemblages as land crabs. We review three tropical coastal ecosystems-mangroves, island maritime forests, and mainland coastal terrestrial forests-where land crabs directly influence forest composition by limiting tree establishment and recruitment. Land crabs differentially prey on seeds, propagules and seedlings along nutrient, chemical and physical environmental gradients. In all of these ecosystems, but especially mangroves, abiotic gradients are well studied, strong and influence plant species distributions. However, we suggest that crab predation has primacy over many of these environmental factors by acting as the first limiting factor of tropical tree recruitment to drive the potential structural and compositional organisation of coastal forests. We show that the influence of crabs varies relative to tidal gradient, shoreline distance, canopy position, time, season, tree species and fruiting periodicity. Crabs also facilitate forest growth and development through such activities as excavation of burrows, creation of soil mounds, aeration of soils, removal of leaf litter into burrows and creation of carbon-rich soil microhabitats. For all three systems, land crabs influence the distribution, density and size-class structure of tree populations. Indeed, crabs are among the major drivers of tree recruitment in tropical coastal forest ecosystems, and their conservation should be included in management plans of these forests. ?? 2009 Cambridge Philosophical Society.

  9. The predator and prey behaviors of crabs: from ecology to neural adaptations.

    Science.gov (United States)

    Tomsic, Daniel; Sztarker, Julieta; Berón de Astrada, Martín; Oliva, Damián; Lanza, Estela

    2017-07-01

    Predator avoidance and prey capture are among the most vital of animal behaviors. They require fast reactions controlled by comparatively straightforward neural circuits often containing giant neurons, which facilitates their study with electrophysiological techniques. Naturally occurring avoidance behaviors, in particular, can be easily and reliably evoked in the laboratory, enabling their neurophysiological investigation. Studies in the laboratory alone, however, can lead to a biased interpretation of an animal's behavior in its natural environment. In this Review, we describe current knowledge - acquired through both laboratory and field studies - on the visually guided escape behavior of the crab Neohelice granulata Analyses of the behavioral responses to visual stimuli in the laboratory have revealed the main characteristics of the crab's performance, such as the continuous regulation of the speed and direction of the escape run, or the enduring changes in the strength of escape induced by learning and memory. This work, in combination with neuroanatomical and electrophysiological studies, has allowed the identification of various giant neurons, the activity of which reflects most essential aspects of the crabs' avoidance performance. In addition, behavioral analyses performed in the natural environment reveal a more complex picture: crabs make use of much more information than is usually available in laboratory studies. Moreover, field studies have led to the discovery of a robust visually guided chasing behavior in Neohelice Here, we describe similarities and differences in the results obtained between the field and the laboratory, discuss the sources of any differences and highlight the importance of combining the two approaches. © 2017. Published by The Company of Biologists Ltd.

  10. Burrowing inhibition by fine textured beach fill: Implications for recovery of beach ecosystems

    Science.gov (United States)

    Viola, Sloane M.; Hubbard, David M.; Dugan, Jenifer E.; Schooler, Nicholas K.

    2014-10-01

    Beach nourishment is often considered the most environmentally sound method of maintaining eroding shorelines. However, the ecological consequences are poorly understood. Fill activities cause intense disturbance and high mortality and have the potential to alter the diversity, abundance, and distribution of intertidal macroinvertebrates for months to years. Ecological recovery following fill activities depends on successful recolonization and recruitment of the entire sandy intertidal community. The use of incompatible sediments as fill material can strongly affect ecosystem recovery. We hypothesized that burrowing inhibition of intertidal animals by incompatible fine fill sediments contributes to ecological impacts and limits recovery in beach ecosystems. We experimentally investigated the influence of intertidal zone and burrowing mode on responses of beach invertebrates to altered sediment texture (28-38% fines), and ultimately the potential for colonization and recovery of beaches disturbed by beach filling. Using experimental trials in fill material and natural beach sand, we found that the mismatched fine fill sediments significantly inhibited burrowing of characteristic species from all intertidal zones, including sand crabs, clams, polychaetes, isopods, and talitrid amphipods. Burrowing performance of all five species we tested was consistently reduced in the fill material and burrowing was completely inhibited for several species. The threshold for burrowing inhibition by fine sediment content in middle and lower beach macroinvertebrates varied by species, with highest sensitivity for the polychaete (4% fines, below the USA regulatory limit of 10% fines), followed by sand crabs and clams (20% fines). These results suggest broader investigation of thresholds for burrowing inhibition in fine fill material is needed for beach animals. Burrowing inhibition caused by mismatched fill sediments exposes beach macroinvertebrates to stresses, which could depress

  11. Courtship herding in the fiddler crab Uca elegans.

    Science.gov (United States)

    How, Martin J; Hemmi, Jan M

    2008-12-01

    Male and female animals are not always complicit during reproduction, giving rise to coercion. One example of a system that is assumed to involve sexual coercion is the mate herding behaviour of fiddler crabs: males push females towards the home burrow with the goal of forcing copulation at the burrow entrance. We recorded and analysed in detail the courtship behaviour of a North Australian species of fiddler crab Uca elegans. Courtship was composed of four main phases: broadcast waving, outward run, herding and at burrow display. During interactions males produced claw-waving displays which were directed posteriorly towards the female and which varied in timing and structure depending on the courtship phase. We suggest that courtship herding in U. elegans is driven primarily by mate choice for the following reasons, (1) females can evade herding, (2) no other reproductive strategies were observed, (3) males broadcast their presence and accompany courtship with conspicuous claw waves, and (4) the behaviour ends with the female leading the male into the home burrow. As an alternative function for herding in U. elegans we suggest that the behaviour represents a form of courtship guiding, in which males direct complicit females to the correct home burrow.

  12. Burrowing owl nesting productivity: A comparison between artificial and natural burrows on and off golf courses

    Science.gov (United States)

    Smith, M.D.; Conway, C.J.; Ellis, L.A.

    2005-01-01

    Burrowing owl (Athene cunicularia) populations are declining in many portions of their range, and lack of suitable nesting burrows is thought to be one reason for observed declines. Burrowing owls are attracted to golf courses because the birds generally nest and forage in short-grass, open areas, yet golf courses seldom have suitable nesting burrows. We examined the efficacy of installing artificial nesting burrows on golf courses as a way to help restore local burrowing owl populations. From 2001-2004 we monitored over 175 natural burrows off golf courses, 14 natural burrows on golf courses, 86 artificial burrows off golf courses, and 130 artificial burrows on golf courses. Owls located and used 8 of the 130 artificial burrows installed on golf courses (4 were used as nests). Owls selected burrows that were closer to existing natural burrows, farther from maintained areas (areas receiving turf maintenance by golf course staff), and farther from sprinkler heads. All 4 of the artificial burrows used as nests successfully fledged young, and annual site fidelity for owls nesting on golf courses was higher than for owls nesting off golf courses. However, annual fecundity of owls nesting on golf courses was lower than that of owls nesting off golf courses. If golf courses have sufficiently large nonmaintained areas and there are nesting owls nearby, course managers potentially can help in restoring local burrowing owl populations by installing artificial nesting burrows on the periphery of the course. However, the low fecundity on golf courses reported here should be more thoroughly examined before artificial burrows are used to attract owls to golf courses.

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

    NARCIS (Netherlands)

    Ens, B; KLAASSEN, M; ZWARTS, L

    1993-01-01

    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

  14. Crab Rationalization Permit Program

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Crab Rationalization Program (Program) allocates BSAI crab resources among harvesters, processors, and coastal communities. The North Pacific Fishery Management...

  15. Burrowing Owls, Pulex irritans, and Plague.

    Science.gov (United States)

    Belthoff, James R; Bernhardt, Scott A; Ball, Christopher L; Gregg, Michael; Johnson, David H; Ketterling, Rachel; Price, Emily; Tinker, Juliette K

    2015-09-01

    Western Burrowing Owls (Athene cunicularia hypugaea) are small, ground-dwelling owls of western North America that frequent prairie dog (Cynomys spp.) towns and other grasslands. Because they rely on rodent prey and occupy burrows once or concurrently inhabited by fossorial mammals, the owls often harbor fleas. We examined the potential role of fleas found on burrowing owls in plague dynamics by evaluating prevalence of Yersinia pestis in fleas collected from burrowing owls and in owl blood. During 2012-2013, fleas and blood were collected from burrowing owls in portions of five states with endemic plague-Idaho, Oregon, Washington, Colorado, and South Dakota. Fleas were enumerated, taxonomically identified, pooled by nest, and assayed for Y. pestis using culturing and molecular (PCR) approaches. Owl blood underwent serological analysis for plague antibodies and nested PCR for detection of Y. pestis. Of more than 4750 fleas collected from owls, Pulex irritans, a known plague vector in portions of its range, comprised more than 99.4%. However, diagnostic tests for Y. pestis of flea pools (culturing and PCR) and owl blood (PCR and serology) were negative. Thus, even though fleas were prevalent on burrowing owls and the potential for a relationship with burrowing owls as a phoretic host of infected fleas exists, we found no evidence of Y. pestis in sampled fleas or in owls that harbored them. We suggest that studies similar to those reported here during plague epizootics will be especially useful for confirming these results.

  16. Burrowing Owl - Palo Verde Valley [ds197

    Data.gov (United States)

    California Natural Resource Agency — These burrowing owl observations were collected during the spring and early summer of 1976 in the Palo Verde Valley, eastern Riverside County, California. This is an...

  17. Potential effect of fiddler crabs on organic matter distribution: A combined laboratory and field experimental approach

    Science.gov (United States)

    Natálio, Luís F.; Pardo, Juan C. F.; Machado, Glauco B. O.; Fortuna, Monique D.; Gallo, Deborah G.; Costa, Tânia M.

    2017-01-01

    Bioturbators play a key role in estuarine environments by modifying the availability of soil elements, which in turn may affect other organisms. Despite the importance of bioturbators, few studies have combined both field and laboratory experiments to explore the effects of bioturbators on estuarine soils. Herein, we assessed the bioturbation potential of fiddler crabs Leptuca leptodactyla and Leptuca uruguayensis in laboratory and field experiments, respectively. We evaluated whether the presence of fiddler crabs resulted in vertical transport of sediment, thereby altering organic matter (OM) distribution. Under laboratory conditions, the burrowing activity by L. leptodactyla increased the OM content in sediment surface. In the long-term field experiment with areas of inclusion and exclusion of L. uruguayensis, we did not observe influence of this fiddler crab in the vertical distribution of OM. Based on our results, we suggest that small fiddler crabs, such as the species used in these experiments, are potentially capable of alter their environment by transporting sediment and OM but such effects may be masked by environmental drivers and spatial heterogeneity under natural conditions. This phenomenon may be related to the small size of these species, which affects how much sediment is transported, along with the way OM interacts with biogeochemical and physical processes. Therefore, the net effect of these burrowing organisms is likely to be the result of a complex interaction with other environmental factors. In this sense, we highlight the importance of performing simultaneous field and laboratory experiments in order to better understanding the role of burrowing animals as bioturbators.

  18. Hemigrapsus sanguineus in Long Island salt marshes: experimental evaluation of the interactions between an invasive crab and resident ecosystem engineers

    Directory of Open Access Journals (Sweden)

    Bradley J. Peterson

    2014-07-01

    Full Text Available The invasive Asian shore crab, Hemigrapsus sanguineus, has recently been observed occupying salt marshes, a novel environment for this crab species. As it invades this new habitat, it is likely to interact with a number of important salt marsh species. To understand the potential effects of H. sanguineus on this ecosystem, interactions between this invasive crab and important salt marsh ecosystem engineers were examined. Laboratory experiments demonstrated competition for burrows between H. sanguineus and the native fiddler crab, Uca pugilator. Results indicate that H. sanguineus is able to displace an established fiddler crab from its burrow. Feeding experiments revealed that the presence of H. sanguineus has a significantly negative impact on the number as well as the biomass of ribbed mussels (Geukensia demissa consumed by the green crab, Carcinus maenas, although this only occurred at high predator densities. In addition, when both crabs foraged together, there was a significant shift in the size of mussels consumed. These interactions suggests that H. sanguineus may have long-term impacts and wide-ranging negative effects on the saltmarsh ecosystem.

  19. Hemigrapsus sanguineus in Long Island salt marshes: experimental evaluation of the interactions between an invasive crab and resident ecosystem engineers.

    Science.gov (United States)

    Peterson, Bradley J; Fournier, Alexa M; Furman, Bradley T; Carroll, John M

    2014-01-01

    The invasive Asian shore crab, Hemigrapsus sanguineus, has recently been observed occupying salt marshes, a novel environment for this crab species. As it invades this new habitat, it is likely to interact with a number of important salt marsh species. To understand the potential effects of H. sanguineus on this ecosystem, interactions between this invasive crab and important salt marsh ecosystem engineers were examined. Laboratory experiments demonstrated competition for burrows between H. sanguineus and the native fiddler crab, Uca pugilator. Results indicate that H. sanguineus is able to displace an established fiddler crab from its burrow. Feeding experiments revealed that the presence of H. sanguineus has a significantly negative impact on the number as well as the biomass of ribbed mussels (Geukensia demissa) consumed by the green crab, Carcinus maenas, although this only occurred at high predator densities. In addition, when both crabs foraged together, there was a significant shift in the size of mussels consumed. These interactions suggests that H. sanguineus may have long-term impacts and wide-ranging negative effects on the saltmarsh ecosystem.

  20. Structural and functional changes of soft-bottom ecosystems in northern fjords invaded by the red king crab (Paralithodes camtschaticus)

    Science.gov (United States)

    Oug, Eivind; Sundet, Jan H.; Cochrane, Sabine K. J.

    2018-04-01

    The red king crab invaded Norwegian coastal waters in the early 1990s after having been introduced from the northern Pacific to the Russian Barents Sea coast. The crab stock increased rapidly in NE northern Norway in the latter half of the 1990s, and since 2002 there has been a commercial fishery in the eastern invaded areas. The crab is an active predator on benthic fauna especially feeding in deep soft-bottom environments. The present study is a follow-up of previous studies (2007-09) to assess the effects of the king crab predation on soft bottom species composition, ecological functioning and sediment quality. Macroinfauna (> 1 mm) was investigated in three fjord areas in the Varanger region with low, moderate and very high crab abundances, respectively. Compared with data from 1994, most benthic species were markedly reduced in abundance, in particular non-moving burrowing and tube-dwelling polychaetes, bivalves and echinoderms. However, a few species appeared to recover from 2007-09 to 2012. Changes in ecological functioning were assessed using 'biological traits analysis (BTA)'. Following the crab invasion there was a relative reduction of suspension and surface deposit feeding species, an increase in mobile and predatory organisms and an increase in those with planktotrophic larval development. From low to high crab abundances functioning changed from tube-building, deep deposit feeding and fairly large size to free-living, shallow burrowing and rather small size. With regard to sediment reworking, downward and upward conveyors were reduced whereas surficial modifiers increased. The changes imply that sediment biomixing and bioirrigation were reduced leading to a degraded sedimentary environment. It is suggested that establishing relationships between ecosystem functioning and crab abundances may form the basis for estimating ecological costs of the crab invasion. Such knowledge is important for managing the crab in the Barents Sea area being both a non

  1. FEEDING ECOLOGY OF TREE-CLIMBING MANGROVE SESARMID CRABS FROM LUZON, PHILIPPINES

    Directory of Open Access Journals (Sweden)

    JIMMY TEVAR MASAGCA

    2009-01-01

    Full Text Available Despite the large ecological study of tree-climbing mangrove sesarmid crabs in other countries, the Philippine representatives appear to have not been investigated extensively. This paper presents the feeding ecology as to dependence on mangrove trees of sesarmids in different mangrove areas of southern Luzon. This is biased on the nature of the crab habitats, arboreal climbing skills and burrowing behavior of the sesarmids: Selatium elongatum and Episesarma versicolor − exclusive mangrove tree climbers (EMTC; Sarmatium germaini − occasional mangrove tree climber (OMTC; and the non-mangrove tree-climbing (NMTC sesarmids- Neosarmatium smithii, Perisesarma bidens and Perisesarma eumolpe

  2. The Crab Nebula

    International Nuclear Information System (INIS)

    Mitton, S.

    1979-01-01

    The subject is covered in chapters, as follows: A.D.1054, a star explodes (historical account of observations of the supernova of which the Crab Nebula is the remnant); the telescope takes over (discovery and subsequent observation of the Crab Nebula); the message of the fiery remnant (detailed structure and its interpretation); the invisible nebula (electromagnetic radiation from the Crab Nebula and its interpretation); a beacon in the night (the discovery of pulsars, with special reference to the pulsar in the Crab Nebula; observation and theory); the strange world of a neutron star (theory, prediction and observation); magnetic fields and energy flow from the pulsar (stellar magnetosphere; luminosity of the nebula); how does the pulsar pulse (observation; models to explain beaming); outburst and aftermath (types of supernovae and their evolution; nucleosynthesis); supernovae and their remnants (account of observations since early records); the Crab Nebula and modern astronomy. (U.K.)

  3. Construction of earthen structure as a sexual signals in the fiddler crabs

    Directory of Open Access Journals (Sweden)

    Noor Us Saher

    2017-03-01

    Full Text Available We studied the reproductive behavior and the construction of an earthen structure in the four species of fiddler crab with reference to their habitat. Males of the Uca sindensis and U. iranica inhibit on open mudflats, construct the pillar and semidome structures at or near to the burrows openings. These structures perform the function to attract females, who wandering on the surface between male burrows for mating as well as provide protection or hiding object against the avian predator to mates. There were no earthen structures were observed in U. urvillie and U. annulipes, which inhibit among the vegetation. The well-marked intersexual different arrangement of mudballs was observed in U. annulipes. The earthen structures (pillar and semidome and mudballs arrangements help courting females to assess the quality of mate as well as internal conditions of the burrow.

  4. Mangrove Crab Ucides cordatus Removal Does Not Affect Sediment Parameters and Stipule Production in a One Year Experiment in Northern Brazil

    Science.gov (United States)

    2016-01-01

    Mangrove crabs influence ecosystem processes through bioturbation and/or litter feeding. In Brazilian mangroves, the abundant and commercially important crab Ucides cordatus is the main faunal modifier of microtopography establishing up to 2 m deep burrows. They process more than 70% of the leaf litter and propagule production, thus promoting microbial degradation of detritus and benefiting microbe-feeding fiddler crabs. The accelerated nutrient turn-over and increased sediment oxygenation mediated by U. cordatus may enhance mangrove tree growth. Such positive feed-back loop was tested in North Brazil through a one year crab removal experiment simulating increased harvesting rates in a mature Rhizophora mangle forest. Investigated response parameters were sediment salinity, organic matter content, CO2 efflux rates of the surface sediment, and reduction potential. We also determined stipule fall of the mangrove tree R. mangle as a proxy for tree growth. Three treatments were applied to twelve experimental plots (13 m × 13 m each): crab removal, disturbance control and control. Within one year, the number of U. cordatus burrows inside the four removal plots decreased on average to 52% of the initial number. Despite this distinct reduction in burrow density of this large bioturbator, none of the measured parameters differed between treatments. Instead, most parameters were clearly influenced by seasonal changes in precipitation. Hence, in the studied R. mangle forest, abiotic factors seem to be more important drivers of ecosystem processes than factors mediated by U. cordatus, at least within the studied timespan of one year. PMID:27907093

  5. Mangrove Crab Ucides cordatus Removal Does Not Affect Sediment Parameters and Stipule Production in a One Year Experiment in Northern Brazil.

    Science.gov (United States)

    Pülmanns, Nathalie; Mehlig, Ulf; Nordhaus, Inga; Saint-Paul, Ulrich; Diele, Karen

    2016-01-01

    Mangrove crabs influence ecosystem processes through bioturbation and/or litter feeding. In Brazilian mangroves, the abundant and commercially important crab Ucides cordatus is the main faunal modifier of microtopography establishing up to 2 m deep burrows. They process more than 70% of the leaf litter and propagule production, thus promoting microbial degradation of detritus and benefiting microbe-feeding fiddler crabs. The accelerated nutrient turn-over and increased sediment oxygenation mediated by U. cordatus may enhance mangrove tree growth. Such positive feed-back loop was tested in North Brazil through a one year crab removal experiment simulating increased harvesting rates in a mature Rhizophora mangle forest. Investigated response parameters were sediment salinity, organic matter content, CO2 efflux rates of the surface sediment, and reduction potential. We also determined stipule fall of the mangrove tree R. mangle as a proxy for tree growth. Three treatments were applied to twelve experimental plots (13 m × 13 m each): crab removal, disturbance control and control. Within one year, the number of U. cordatus burrows inside the four removal plots decreased on average to 52% of the initial number. Despite this distinct reduction in burrow density of this large bioturbator, none of the measured parameters differed between treatments. Instead, most parameters were clearly influenced by seasonal changes in precipitation. Hence, in the studied R. mangle forest, abiotic factors seem to be more important drivers of ecosystem processes than factors mediated by U. cordatus, at least within the studied timespan of one year.

  6. Status of the population structure of the mangrove crab Ucides cordatus (Decapoda: Ocypodidae) on the Piraquê-açu River estuary, Espírito Santo, Brazil

    OpenAIRE

    Conti, Rita de Cássia; Nalesso, Rosebel Cunha

    2010-01-01

    The land crab Ucides cordatus is a keystone species of neotropical mangrove forests and an important resource of the artisanal fisheries. The spatial and temporal distribution of U. cordatus in the mangrove area of the Piraquê-açu river estuary was determined following a longitudinal estuarine salinity gradient (lower, middle, upper estuary) and along the vertical intertidal gradient. The numbers of open and closed burrows were counted monthly on fixed transects, the inhabiting crabs were cau...

  7. The role of burrowing sponges in bioerosion.

    Science.gov (United States)

    Rützler, Klaus

    1975-09-01

    Among the large number of limestone-eroding organisms, sponges, mainly of the family Clinonidae are of special interest because of their efficient means of substratum penetration by cellular etching and because they release characteristically shaped calcium carbonate chips which can be detected in the mud-size fraction of many sediments. Identifiable trace fossils and sediments are of great ecological and paleoecological significance.As new data on the excavating mechanism have become available, the questions of burrowing rates and sediment production have gained importance. Extrapolation from shortterm experiments (under 6 months) on substrate invasion are inconclusive because of high initial penetration rates resulting from mechanical stimulation and lack of competition. New experiments show that the rate curve flattens after 6 months and that optimum longterm erosion of CaCO 3 does not exceed 700 mg m -2 year -1 (Cliona lampa and C. aprica). Substrate limitations and competition will further reduce this rate.By monitoring the production of CaCO 3 chips by Cliona lampa, it was possible to link activity patterns to certain environmental factors. Mechanical stimuli, high light intensity, strong currents and, possibly, low temperature seem to accelerate the burrowing process. Sponge-generated chips can make up over 40% of coral mud when deposited in the current shadow of the reef framework.Using transect counts and sponge area-biomass conversion factors, the mean abundance of burrowing sponges on the Bermuda platform could be calculated. On suitable hard bottom substrates it averages 16 g dry weight per m 2 . From this value the burrowing potential of sponges can be estimated as 256 g CaCO 3 per m 2 substrate per year. Since 97-98% of the eroded limestone remains in particulate form, the contribution of fine sediments can amount to 250 g m -2 year -1 .Attention is called to the fact that erosion rates by burrowers can not directly be compared with those of borers or

  8. Evolution of king crabs from hermit crab ancestors

    Science.gov (United States)

    Cunningham, C. W.; Blackstone, N. W.; Buss, L. W.

    1992-02-01

    KING crabs (Family Lithodidae) are among the world's largest arthropods, having a crab-like morphology and a strongly calcified exoskeleton1-6. The hermit crabs, by contrast, have depended on gastropod shells for protection for over 150 million years5,7. Shell-living has constrained the morphological evolution of hermit crabs by requiring a decalcified asymmetrical abdomen capable of coiling into gastropod shells and by preventing crabs from growing past the size of the largest available shells1-6. Whereas reduction in shell-living and acquisition of a crab-like morphology (carcinization) has taken place independently in several hermit crab lineages, and most dramatically in king crabs1-6, the rate at which this process has occurred was entirely unknown2,7. We present molecular evidence that king crabs are not only descended from hermit crabs, but are nested within the hermit crab genus Pagurus. We estimate that loss of the shell-living habit and the complete carcinization of king crabs has taken between 13 and 25 million years.

  9. Burrowing Owl Monitoring Report for Calendar Year 2012

    Energy Technology Data Exchange (ETDEWEB)

    Wilde, Justin W.; Lindsey, Cole T.; Nugent, John J.

    2013-03-14

    The monitoring during 2012 focused on documenting the status of known burrows. Newly identified burrows were documented while examining historical locations, during ecological resource reviews, or discovered during other monitoring efforts. The timing of the monitoring effort allowed staff to perform the surveys without disrupting any breeding or hatching, while also allowing for easy discernment of adults from juveniles, which helped in determining burrow-use type.

  10. Leaf removal by sesarmid crabs in Bangrong mangrove forest, Phuket, Thailand; with emphasis on the feeding ecology of Neoepisesarma versicolor

    Science.gov (United States)

    Thongtham, Nalinee; Kristensen, Erik; Puangprasan, Som-Ying

    2008-12-01

    Field measurements on leaf removal by populations of sesarmid crabs at different locations in the Bangrong mangrove forest, Phuket, Thailand, indicated that crabs on average can remove 87% of the daily leaf litter fall by ingestion or burial. The removal rate is correlated positively with the number of crab burrows and negatively with tidal inundation time. The results from the field were supplemented with observations on the behavior of Neoepisesarma versicolor in laboratory microcosms and a mangrove mesocosm. N. versicolor feeds primarily at night and total time spent feeding was up to an order of magnitude higher in the artificial microcosms than under simulated in situ conditions in the mesocosm. Most of the time during both day and night was spent resting near the entrance or inside burrows. N. versicolor mainly feeds on mangrove leaves and scraps of food material from the sediment surface. This is supported by examinations of stomach content, which showed that 62% is composed of higher plant material and 38% of detritus and mineral particles from the sediment. The nutritive value of leaves and detritus is insufficient to maintain crab growth. Sesarmid crabs may instead obtain the needed nutrients by occasional consumption of nitrogen-rich animal tissues, such as carcasses of fish and crustaceans, as indicated by the presence of animal remains in the stomach and the willingness of crabs to consume fish meat. Laboratory experiments on leaf consumption and leaf preferences of N. versicolor indicate that they preferentially feed on brown leaves, if available, followed by green and yellow leaves. If all species of sesarmid crabs in the Bangrong mangrove forest consume leaves at the same rate as N. versicolor, they could potentially ingest 52% of the total litter fall.

  11. Orofacial neuropathic pain reduces spontaneous burrowing behavior in rats.

    Science.gov (United States)

    Deseure, K; Hans, G

    2018-07-01

    It was recently reported that spontaneous burrowing behavior is decreased after tibial nerve transection, spinal nerve transection and partial sciatic nerve ligation. It was proposed that spontaneous burrowing could be used as a measure of the impact of neuropathic pain after peripheral nerve injury. It has remained unclear whether the reduction in burrowing behavior is caused directly by pain or hypersensitivity in the affected limbs, making it more difficult to perform burrowing, or by a pain induced decrease in the general wellbeing, thus reducing the motivation to burrow. We studied burrowing behavior after infraorbital nerve injury, a model of orofacial neuropathic pain that does not affect the limbs. Burrowing behavior was significantly reduced after infraorbital nerve injury. Isolated face grooming and responsiveness to mechanical von Frey stimulation of the infraorbital nerve territory were significantly increased after infraorbital nerve injury, indicative, respectively, of spontaneous pain and mechanical allodynia. It is concluded that spontaneous burrowing may provide a measure of the global impact of pain on the animal's wellbeing after peripheral nerve injury and incorporation of this behavioral assay in preclinical drug testing may improve the predictive validity of currently used pain models. Copyright © 2018 Elsevier Inc. All rights reserved.

  12. Burrow architecture of the Damaraland mole-rat ( Fukomys ...

    African Journals Online (AJOL)

    The burrow architecture (length, internal dimensions, fractal dimension of tunnel systems, number of nesting chambers and surface mounds) was investigated in the Damaraland mole-rat (Fukomys damarensis). A total of 31 animals were caught from five different colonies and their burrow systems were excavated in their ...

  13. Space Movie Reveals Shocking Secrets Of The Crab Pulsa

    Science.gov (United States)

    2002-09-01

    particles and magnetic field. "The jet looks like steam from a high pressure boiler," said David Burrows of Penn State, another coauthor of the paper. "Except when you realize you are looking at a stream of matter and anti-matter electrons moving at half the speed of light!" Time-Lapse Movie Of Crab Pulsar Wind Time-Lapse Movie Of Crab Pulsar Wind The inner region of the Crab Nebula around the pulsar was observed with Hubble on 24 occasions between August 2000 and April 2001 at 11-day intervals, and with Chandra on eight occasions between November 2000 and April 2001. The Crab was observed with Chandra's Advanced CCD Imaging Spectrometer and Hubble's Wide-Field Planetary Camera. NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program, and TRW, Inc., Redondo Beach, Calif., is the prime contractor. The Smithsonian's Chandra X-ray Center controls science and flight operations from Cambridge, Mass. The Space Telescope Science Institute is operated by the Association of Universities for Research in Astronomy, Inc. (AURA), for NASA, under contract with the Goddard Space Flight Center, Greenbelt, Md. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency (ESA).

  14. Dry season distribution of land crabs, Gecarcinus quadratus (Crustacea: Gecarcinidae, in Corcovado National Park, Costa Rica

    Directory of Open Access Journals (Sweden)

    Megan E Griffiths

    2007-03-01

    Full Text Available The land crab Gecarcinus quadratus is an engineering species that controls nutrient cycling in tropical forests. Factors regulating their coastal distribution are not fully understood. We quantified land crab distribution during the dry season at Sirena Field Station in Corcovado National Park, Costa Rica, and found that land crab burrow density decreases with increasing distance from the ocean. Leaf litter depth and tree seedling density are negatively correlated with land crab burrow density. Burrows are strongly associated with sand substrate and burrow density is comparatively low in clay substrate. Results suggest that G. quadratus is limited to a narrow coastal zone with sand substrate, and this distribution could have profound effects on plant community structure. Rev. Biol. Trop. 55 (1: 219-224. Epub 2007 March. 31.El cangrejo terrestre Gecarcinus quadratus es una especie "ingeniera" que controla el ciclo de nutrientes en los bosques tropicales. Los factores que regulan su distribución a lo largo de las costas no se conocen de forma definitiva. Se cuantificó la distribución del cangrejo terrestre durante la estación seca en la Estación de Campo Sirena en el Parque Nacional de Corcovado, Costa Rica, y se encontró que la densidad de galerías del cangrejo terrestre disminuye al aumentar la distancia al océano. La profundidad de la hojarasca y la densidad de plántulas de especies arbóreas están negativamente correlacionadas con la densidad de galerías del cangrejo terrestre. Las galerías aparecen fuertemente asociadas con el sustrato arenoso y la densidad de galerías es comparativamente más baja en sustratos arcillosos. Estos resultados sugieren que G. quadratus se encuentra en una zona costera estrecha con sustrato arenoso, y que esta distribución podría tener efectos importantes en la estructura de la comunidad vegetal.

  15. Crab cavities for linear colliders

    CERN Document Server

    Burt, G; Carter, R; Dexter, A; Tahir, I; Beard, C; Dykes, M; Goudket, P; Kalinin, A; Ma, L; McIntosh, P; Shulte, D; Jones, Roger M; Bellantoni, L; Chase, B; Church, M; Khabouline, T; Latina, A; Adolphsen, C; Li, Z; Seryi, Andrei; Xiao, L

    2008-01-01

    Crab cavities have been proposed for a wide number of accelerators and interest in crab cavities has recently increased after the successful operation of a pair of crab cavities in KEK-B. In particular crab cavities are required for both the ILC and CLIC linear colliders for bunch alignment. Consideration of bunch structure and size constraints favour a 3.9 GHz superconducting, multi-cell cavity as the solution for ILC, whilst bunch structure and beam-loading considerations suggest an X-band copper travelling wave structure for CLIC. These two cavity solutions are very different in design but share complex design issues. Phase stabilisation, beam loading, wakefields and mode damping are fundamental issues for these crab cavities. Requirements and potential design solutions will be discussed for both colliders.

  16. The porcellanid crabs of the Isla Gorgona, Pacific Coast of Colombia, with a description of Clastotoechus gorgonensis sp. nov. (Crustacea: Anomura)

    OpenAIRE

    Werding, B.; Haig, J.

    1982-01-01

    A collection of porcellanid crabs was made on che Isla Gorgona, Colombia, during a one week period, sampling as completely as possible a number of different biotopes. The majority of the 16 species in six genera that were collected occurred in the formations of pocilloporid corals and between stones in the sublittoral zone. Clastotoechus gorgonensis sp. nov. lives in the burrows of the sea urchin Echinometra vanbrunti A. Agassiz in the intertidal zone. Seven species are new additions to the ...

  17. Crab As A Coconut Oil Separating Agent

    OpenAIRE

    Margino, Sebastian

    2017-01-01

    The role of sterilized and nonsterilized crab extract on the separation of coconut oil was examined using grated coconut meat as substrate. Sterilized crab extract was prepared by suspension and centrifugation of crushed crab and then filtrated using Millipore Utter. Sterilized crab extract has proteolytic activity but not lipolytic one. It was found that the sterilized crab extract supported the growth of proteolytic microbes, isolated from fermentation process of coconut oil. Both sterilize...

  18. Incorporation of microplastics from litter into burrows of Lumbricus terrestris.

    Science.gov (United States)

    Huerta Lwanga, Esperanza; Gertsen, Hennie; Gooren, Harm; Peters, Piet; Salánki, Tamás; van der Ploeg, Martine; Besseling, Ellen; Koelmans, Albert A; Geissen, Violette

    2017-01-01

    Pollution caused by plastic debris is an urgent environmental problem. Here, we assessed the effects of microplastics in the soil surface litter on the formation and characterization of burrows built by the anecic earthworm Lumbricus terrestris in soil and quantified the amount of microplastics that was transported and deposited in L. terrestris burrows. Worms were exposed to soil surface litter treatments containing microplastics (Low Density Polyethylene) for 2 weeks at concentrations of 0%, 7%, 28%, 45% and 60%. The latter representing environmentally realistic concentrations found in hot spot soil locations. There were significantly more burrows found when soil was exposed to the surface treatment composed of 7% microplastics than in all other treatments. The highest amount of organic matter in the walls of the burrows was observed after using the treatments containing 28 and 45% microplastics. The highest microplastic bioturbation efficiency ratio (total microplastics (mg) in burrow walls/initial total surface litter microplastics (mg)) was found using the concentration of 7% microplastics, where L. terrestris introduced 73.5% of the surface microplastics into the burrow walls. The highest burrow wall microplastic content per unit weight of soil (11.8 ± 4.8 g kg- 1 ) was found using a concentration of 60% microplastics. L. terrestris was responsible for size-selective downward transport when exposed to concentrations of 7, 28 and 45% microplastics in the surface litter, as the fraction ≤50 μm microplastics in burrow walls increased by 65% compared to this fraction in the original surface litter plastic. We conclude that the high biogenic incorporation rate of the small-fraction microplastics from surface litter into burrow walls causes a risk of leaching through preferential flow into groundwater bodies. Furthermore, this leaching may have implications for the subsequent availability of microplastics to terrestrial organisms or for the transport

  19. Photo-induced toxicity in early life stage fiddler crab (Uca longisignalis) following exposure to Deepwater Horizon oil.

    Science.gov (United States)

    Damare, Leigh M; Bridges, Kristin N; Alloy, Matthew M; Curran, Thomas E; Soulen, Brianne K; Forth, Heather P; Lay, Claire R; Morris, Jeffrey M; Stoeckel, James A; Roberts, Aaron P

    2018-05-01

    The 2010 explosion of the Deepwater Horizon (DWH) oil rig led to the release of millions of barrels of oil in the Gulf of Mexico. Oil in aquatic ecosystems exerts toxicity through multiple mechanisms, including photo-induced toxicity following co-exposure with UV radiation. The timing and location of the spill coincided with both fiddler crab reproduction and peak yearly UV intensities, putting early life stage fiddler crabs at risk of injury due to photo-induced toxicity. The present study assessed sensitivity of fiddler crab larvae to photo-induced toxicity during co-exposure to a range of environmentally relevant dilutions of high-energy water accommodated fractions of DWH oil, and either dark recovery period (duration: 17-h) in between. Survival was significantly decreased in treatments the presence of >10% UV and relatively low concentrations of oil. Results of the present study indicate fiddler crab larvae are sensitive to photo-induced toxicity in the presence of DWH oil. These results are of concern, as fiddler crabs play an important role as ecosystem engineers, modulating sediment biogeochemical processes via burrowing action. Furthermore, they occupy an important place in the food web in the Gulf of Mexico.

  20. The burrowing characteristics of three common earthworm species

    International Nuclear Information System (INIS)

    Francis, G.S.; Tabley, F.J.; Butler, R.C.; Fraser, P.M.

    2001-01-01

    The burrowing characteristics of 3 common earthworm species were studied using X-ray computed tomography (CT) scanning in large cylinders (24.1 cm diameter) packed with topsoil (0-25 cm) and subsoil (25-50 cm) to representative field bulk density values and sown with ryegrass. Replicated cylinders (n 3), kept under constant moisture and temperature conditions, were inoculated with mature species of Lumbricus rubellus, Aporrectodea caliginosa, or Octolasion cyaneum earthworms at rates similar to their population density in the field. A non-inoculated, unreplicated control was also included. The number, biomass, and activity of the 3 species were then examined. X-ray CT scanning of large-diameter soil cylinders offers an alternative method for obtaining information on the burrowing characteristics of earthworms (Jegou et al. 1999). As this method is non-destructive, repeat measurements can be made and the use of large cylinders minimises edge effects. The objectives of this study were to: (i) assess the burrowing characteristics of 3 earthworm species (under artificial conditions) through measurement of 2-D porosity using X-ray CT scanning, (ii) estimate the extent of burrow backfilling between sequential scans, and (iii) estimate the continuity of earthworm burrows with depth through hydraulic conductivity measurements. Copyright (2001) CSIRO Publishing

  1. Use of Artificial Burrows by Burrowing Owls (Athene cunicularia) at the HAMMER Facility on the U.S. Department of Energy Hanford Site

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, Amanda K.; Sackschewsky, Michael R.; Duberstein, Corey A.

    2005-09-30

    In 2003 the U.S. Department of Energy (DOE) constructed an Emergency Vehicle Operations Course (EVOC) at the Hazardous Material Management and Emergency Response Training and Education Center (HAMMER) in the southern portion of the Hanford Site. Preliminary surveys during 2001 identified an active burrowing owl (Athene cunicularia) burrow and three burrowing owls within the proposed development area. Burrowing owls were classified as a federal species of concern, a Washington State ?candidate? species, a Washington Department of Fish and Wildlife priority species, and a Hanford Site Biological Resources Management Plan Level III resource. Therefore, the mitigation action plan for the project included the installation of twenty artificial burrows around EVOC in the spring of 2003. The mitigation plan established a success criterion of five percent annual use of the burrows by owls. In July 2005, a field survey of the EVOC burrow complex was conducted to determine use and demography at each site. Burrow locations were mapped and signs of activity (feces, owl tracks, castings, feathers) were recorded. Out of the twenty burrows, twelve were found to be active. Of the eight inactive burrows three appeared to have been active earlier in the 2005 breeding season. A total of nineteen owls were counted but demography could not be determined. It appears that the EVOC mitigation exceeded burrow use goals during 2005. Continued site monitoring and maintenance, according to mitigation plan guidelines should be conducted as prescribed.

  2. What regulates crab predation on mangrove propagules?

    Science.gov (United States)

    Van Nedervelde, Fleur; Cannicci, Stefano; Koedam, Nico; Bosire, Jared; Dahdouh-Guebas, Farid

    2015-02-01

    Crabs play a major role in some ecosystems. To increase our knowledge about the factors that influence crab predation on propagules in mangrove forests, we performed experiments in Gazi Bay, Kenya in July 2009. We tested whether: (1) crab density influences propagule predation rate; (2) crab size influences food competition and predation rate; (3) crabs depredate at different rates according to propagule and canopy cover species; (4) vegetation density is correlated with crab density; (5) food preferences of herbivorous crabs are determined by size, shape and nutritional value. We found that (1) propagule predation rate was positively correlated to crab density. (2) Crab competitive abilities were unrelated to their size. (3) Avicennia marina propagules were consumed more quickly than Ceriops tagal except under C. tagal canopies. (4) Crab density was negatively correlated with the density of A. marina trees and pneumatophores. (5) Crabs prefer small items with a lower C:N ratio. Vegetation density influences crab density, and crab density affects propagule availability and hence vegetation recruitment rate. Consequently, the mutual relationships between vegetation and crab populations could be important for forest restoration success and management.

  3. Golden Crab Logbook Survey (Vessels)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In November 1995, a voluntary logbook program for the golden crab fishery in the waters under the jurisdiction of the South Atlantic Fishery Management Council...

  4. Plant cover effect on Bolson tortoise (Gopherus flavomarginatus Legler 1959, Testudinidae burrow use

    Directory of Open Access Journals (Sweden)

    Jorge Luis Becerra-López

    2017-03-01

    Full Text Available The Bolson tortoise, Gopherus flavomarginatus, occurs within a restricted geographical area in the Mexican Chihuahuan Desert. We analyzed the variation in surface microhabitat with relation to the burrow occupancy for this tortoise at the Mapimí Biosphere Reserve, Mexico. In summer 2010, we monitored burrow activity (active, inactive, or abandoned and measured environmental factors that might influence the burrow’s occupancy by tortoises (air temperature, relative humidity and substrate temperature, both inside and outside the burrow, and the plant cover around it. Discriminant analysis was used to identify the importance of these variables influencing burrow occupancy. Correlation and linear regression analyses were performed to quantify the relation between environmental factors in the sampled burrows. Results. Sixty-one burrows were identified at the Tortugas locality. The first function’s auto-value analysis indicates that this function explains 97.9% of the variation in burrow activity status; high occupancy scores were associated with low substrate temperature inside the burrow. Plant cover was inversely proportional to substrate temperature inside the burrow. These results suggest the importance the density of plants surrounding the tortoise’s burrow as a key factor influencing the burrow microclimate and occupancy by the tortoises. Conclusions. Gopherus flavomarginatus inhabits burrows, in part, based on microhabitat structure, with plant cover being a main factor influencing burrow occupancy. Our findings indicate that human land use and vegetation management are important for conserving Bolson tortoises, and for understanding habitat conditions necessary for the successful establishment of populations elsewhere.

  5. Antarctic crabs: invasion or endurance?

    Directory of Open Access Journals (Sweden)

    Huw J Griffiths

    Full Text Available Recent scientific interest following the "discovery" of lithodid crabs around Antarctica has centred on a hypothesis that these crabs might be poised to invade the Antarctic shelf if the recent warming trend continues, potentially decimating its native fauna. This "invasion hypothesis" suggests that decapod crabs were driven out of Antarctica 40-15 million years ago and are only now returning as "warm" enough habitats become available. The hypothesis is based on a geographically and spatially poor fossil record of a different group of crabs (Brachyura, and examination of relatively few Recent lithodid samples from the Antarctic slope. In this paper, we examine the existing lithodid fossil record and present the distribution and biogeographic patterns derived from over 16,000 records of Recent Southern Hemisphere crabs and lobsters. Globally, the lithodid fossil record consists of only two known specimens, neither of which comes from the Antarctic. Recent records show that 22 species of crabs and lobsters have been reported from the Southern Ocean, with 12 species found south of 60 °S. All are restricted to waters warmer than 0 °C, with their Antarctic distribution limited to the areas of seafloor dominated by Circumpolar Deep Water (CDW. Currently, CDW extends further and shallower onto the West Antarctic shelf than the known distribution ranges of most lithodid species examined. Geological evidence suggests that West Antarctic shelf could have been available for colonisation during the last 9,000 years. Distribution patterns, species richness, and levels of endemism all suggest that, rather than becoming extinct and recently re-invading from outside Antarctica, the lithodid crabs have likely persisted, and even radiated, on or near to Antarctic slope. We conclude there is no evidence for a modern-day "crab invasion". We recommend a repeated targeted lithodid sampling program along the West Antarctic shelf to fully test the validity of the

  6. Exposure of burrowing mammals to {sup 222}Rn

    Energy Technology Data Exchange (ETDEWEB)

    Beresford, N.A., E-mail: nab@ceh.ac.uk [NERC Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Av. Bailrigg, Lancaster LA1 4AP (United Kingdom); Barnett, C.L. [NERC Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Av. Bailrigg, Lancaster LA1 4AP (United Kingdom); Vives i Batlle, J. [Belgian Nuclear Research Centre (SCK-CEN), Boeretang 200, 2400 Mol (Belgium); Potter, E.D. [NERC Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Av. Bailrigg, Lancaster LA1 4AP (United Kingdom); Ibrahimi, Z.-F. [Health Protection Agency, Centre for Radiation, Chemical and Environmental Hazards, Chilton, Didcot OX11 0RQ (United Kingdom); Barlow, T.S.; Schieb, C.; Jones, D.G. [British Geological Survey, Environmental Science Centre, Keyworth, Nottingham NG12 5GG (United Kingdom); Copplestone, D. [School of Natural Sciences, University of Stirling, Stirling FK9 4LA (United Kingdom)

    2012-08-01

    Estimates of absorbed dose rates to wildlife from exposure to natural background radionuclides are required to put estimates of dose rates arising from regulated releases of radioactivity and proposed benchmarks into context. Recent review papers have estimated dose rates to wildlife from {sup 40}K, and {sup 238}U and {sup 232}Th series radionuclides. However, only one study previous has considered the potential dose rates to burrowing animals from inhaled {sup 222}Rn and its daughter products. In this paper we describe a study conducted at seven sites in northwest England. Passive track etch detectors were used to measure the {sup 222}Rn concentrations in artificial burrows over a period of approximately one year. Results suggest that absorbed dose rates to burrowing mammals as a consequence of exposure to {sup 222}Rn are likely to be at least an order of magnitude higher than those suggested in previous evaluations of natural background exposure rates which had omitted this radionuclide and exposure pathway. Dose rates in some areas of Great Britain will be considerably in excess of incremental no-effects benchmark dose rates suggested for use as screening levels. Such advised benchmark dose rates need to be better put into context with background dose rates, including exposure to {sup 222}Rn, to ensure credibility; although the context will be determined by the purpose of the benchmark and the assessment level. - Highlights: Black-Right-Pointing-Pointer Determined {sup 222}Rn concentrations in artificial burrows. Black-Right-Pointing-Pointer Estimated dose rates to burrowing mammals from inhaled {sup 222}Rn and daughter products. Black-Right-Pointing-Pointer {sup 222}Rn likely to dominate exposure of burrowing mammals due to natural radionuclides.

  7. Ventilation of multi-entranced rodent burrows by boundary layer eddies.

    Science.gov (United States)

    Brickner-Braun, Inbal; Zucker-Milwerger, Daniel; Braun, Avi; Turner, J Scott; Pinshow, Berry; Berliner, Pedro

    2014-12-01

    Rodent burrows are often assumed to be environments wherein the air has a high concentration of CO₂. Although high burrow [CO₂] has been recorded, many studies report burrow [CO₂] that differs only slightly from atmospheric concentrations. Here, we advocate that one of the reasons for these differences is the penetration into burrows of air gusts (eddies), which originate in the turbulent boundary layer and prevent build-up of CO₂. We have characterized the means by which burrows of Sundevall's jird, which are representative of the burrows of many rodent species with more than one entrance, are ventilated. Our results demonstrate that, even at low wind speeds, the random penetration of eddies into a burrow through its openings is sufficient to keep the burrow [CO₂] low enough to be physiologically inconsequential, even in its deep and remote parts. © 2014. Published by The Company of Biologists Ltd.

  8. Pubic "Crab" Lice Prevention and Control

    Science.gov (United States)

    ... and General Public. Contact Us Parasites Home Prevention & Control Recommend on Facebook Tweet Share Compartir Pubic ("crab") ... that can be taken to help prevent and control the spread of pubic ("crab") lice: All sexual ...

  9. Modeling seasonal detection patterns for burrowing owl surveys

    Science.gov (United States)

    Quresh S. Latif; Kathleen D. Fleming; Cameron Barrows; John T. Rotenberry

    2012-01-01

    To guide monitoring of burrowing owls (Athene cunicularia) in the Coachella Valley, California, USA, we analyzed survey-method-specific seasonal variation in detectability. Point-based call-broadcast surveys yielded high early season detectability that then declined through time, whereas detectability on driving surveys increased through the season. Point surveys...

  10. Incorporation of microplastics from litter into burrows of Lumbricus terrestris

    NARCIS (Netherlands)

    Huerta Lwanga, Esperanza; Gertsen, H.F.; Gooren, H.; Peters, P.; Salanki, T.E.; Ploeg, van der M.; Besseling, E.; Koelmans, A.A.; Geissen, V.

    2017-01-01

    Pollution caused by plastic debris is an urgent environmental problem. Here, we assessed the effects of microplastics in the soil surface litter on the formation and characterization of burrows built by the anecic earthworm Lumbricus terrestris in soil and quantified the amount of microplastics that

  11. Burgess shale-type biotas were not entirely burrowed away

    DEFF Research Database (Denmark)

    Gaines, Robert R.; Droser, Mary L.; Orr, Patrick J.

    2012-01-01

    environments is that soft-bodied biotas were literally burrowed away from the fossil record by increasing infaunal activity in muddy substrate environments; this would have affected geochemical gradients and increased the efficiency of organic matter recycling in sediments. New and recently published data...

  12. Daily and seasonal temperatures in the burrows of African rodent ...

    African Journals Online (AJOL)

    1987-03-02

    Mar 2, 1987 ... temperature extremes, containing a nest and a bolt-hole. (Jarvis & Sale 1971; Davies & Jarvis 1986; Lovegrove &. Painting 1987). In the burrow systems of Cryptomys damarensis we have found nests as deep as 2,5 m below ground. Dissimilarities in ..... The live-trap in which it was confined was shaded ...

  13. Protozoal hepatitis in a western burrowing owl (Athene cunicularia hypugaea)

    Science.gov (United States)

    Franson, J. Christian

    2017-01-01

    A western burrowing owl (Athene cunicularia hypugaea) found dead in southern California had many light-colored lesions visible grossly on its liver, and histopathology revealed extensive necrosis throughout the hepatic parenchyma. Single-celled organisms were seen in clear spaces within the areas of necrosis. The owl was diagnosed with protozoal hepatitis.

  14. Oxygen penetration around burrows and roots in aquatic sediments

    DEFF Research Database (Denmark)

    Meysman, Filip J.R.; Galaktionov, O.S.; Glud, Ronnie N.

    2010-01-01

    Diffusion is the dominant physical mechanism for the transfer of oxygen into fine-grained aquatic sediments. This diffusive uptake occurs at the sediment-water interface, but also at internal interfaces, such as along ventilated burrows or O2 releasing plant roots. Here, we present a systematic...

  15. An example of burrow system architecture of dispersing Damaraland ...

    African Journals Online (AJOL)

    The Damaraland mole-rat (Fukomys damarensis) is a social, subterranean rodent that occurs in the red Kalahari sands. This species exhibits extreme reproductive skew with a single breeding female whereas reproduction in subordinate group members is completely blocked. Rainfall, as it greatly facilitates burrowing, ...

  16. Seasonal effects on digging activity and burrow architecture in the ...

    African Journals Online (AJOL)

    Most polygynous male mammals exhibit little or no parental care or involvement raising young. Instead, they invest indirectly in their own morphological and physiological attributes which enhance their chance of reproduction. Such secondary morphological sex traits may contribute to differences in the burrow architecture ...

  17. Litter processing and population food intake of the mangrove crab Ucides cordatus in a high intertidal forest in northern Brazil

    Science.gov (United States)

    Nordhaus, Inga; Wolff, Matthias; Diele, Karen

    2006-03-01

    This study provides the first quantification of the population food intake of the litter-consuming mangrove crab Ucides cordatus (Ocypodidae, L. 1763) in a New World mangrove forest. Diet, feeding periodicity, gastric evacuation rates and size-dependent consumption were determined for this intensively exploited semi-terrestrial crab in different types of mangrove forest. Unlike many other crabs Ucides cordatus is a continuous feeder, as shown by gastrointestinal contents over a day's cycle. Starvation experiments revealed that most gastric evacuation occurs during the first 12 h after feeding, following an exponential decay function. Evacuation rates (0.35 h -1 and 0.31 h -1) for small (carapace width CW 2.5-3.5 cm) and large (CW 6.5-7.5 cm) crabs, respectively, and the mean daily gastrointestinal contents were used to calculate the daily food intake (DFI) of U. cordatus for both sexes and different size classes. DFI was strongly correlated to body size and ranged from 19.8 to 6.0% of body dry weight in small and large crabs, respectively. The daily energy intake of U. cordatus (37.6 kJ for a 65 g wet weight specimen) was high when compared to other leaf-eating crabs. Litter fall and propagule production were calculated as 16.38 t ha -1 y -1, corresponding to a daily mean of 4.49 g m -2 in a high intertidal Rhizophora mangle forest stand. The estimated population food intake of Ucides cordatus (4.1 g dw m -2 d -1) corresponds to 81.3% of this production. This high litter removal rate, a low litter quantity in burrows and high consumption rates during field experiments suggest that the local crab population is food-limited in many parts of the study area. The very efficient coupling of forest litter production and crab litter consumption is possible due to the high crab density and the low inundation frequency of the mangrove forests, allowing for prolonged foraging periods. By processing the major part of the litter, U. cordatus helps to retain nutrients and energy

  18. Caught in the Crab's claws

    CERN Multimedia

    2001-01-01

    'The crab', a new cryo magnet transport vehicle, starts work at CERN. Produced by the ESI group of EST division and built in Finland, it has the job of transporting LHC magnets in buildings SM18 and SMA18. If you see a huge crab scuttling around building SMA18 don't be afraid! It is the new Cryo Magnet Transport Vehicle produced by the ESI group (Engineering Support for Infrastructure, EST Division) for CERN's LHC project and built by Finnish Company ROCLA. This orange vehicle, nicknamed 'The Crab', is perhaps the strangest piece of equipment used for the construction of LHC magnets. It will start work at the end of this month. The crab will be used to transport LHC cryo-magnets and their components in the assembly and preparation building, SMA18, and test building, SM18. It has many capabilities that will allow CERN staff and contractors transport magnets between the two buildings and to locate them in the right position on the test beds. The crab in action during its first tests on 8 February. How does th...

  19. Shrimp burrow in tropical seagrass meadows: An important sink for litter

    Science.gov (United States)

    Vonk, Jan Arie; Kneer, Dominik; Stapel, Johan; Asmus, Harald

    2008-08-01

    The abundance, burrow characteristics, and in situ behaviour of the burrowing shrimps Neaxius acanthus (Decapoda: Strahlaxiidae) and Alpheus macellarius (Decapoda: Alpheidae) were studied to quantify the collection of seagrass material, to identify the fate of this collected material, and to determine the importance of these burrowing crustaceans in the nutrient (nitrogen and phosphorus) cycling of two tropical seagrass meadows on Bone Batang, South Sulawesi, Indonesia. Alpheus macellarius harvested 0.70 g dry weight (DW) burrow -1 d -1 seagrass material, dominantly by active cutting of fresh seagrass leaves. Neaxius acanthus collected 1.66 g DW burrow -1 d -1, mainly detached leaves which floated past the burrow opening. The A. macellarius and N. acanthus communities together collected in their burrows an amount of seagrass leaf material corresponding to more than 50% of the leaf production in the meadows studied. The crustacean species studied might therefore fulfil an important function in the nutrient cycling of tropical meadows. In the burrow most of the collected material is shredded into pieces. The burrows of both species had special chambers which serve as a storage for seagrass leaf material. Neaxius acanthus incorporated most of the material into the burrow wall lining, which is made of small sediment particles and macerated seagrass leaves. Phosphate concentrations measured in N. acanthus burrows compared with pore-water and water-column concentrations suggests that a substantial amount of the seagrass material undergoes decomposition in the burrows. Oxygen levels measured in these water bodies are indicative for a possible exchange of water between the burrow and its surroundings, most likely supported by the shrimps irrigating their burrows. By collecting leaf material in their burrows, nutrients that are otherwise lost from the seagrass meadow associated with detached leaves and leaf fragments carried away in the water column, are maintained in the

  20. Context-dependent memory traces in the crab's mushroom bodies: Functional support for a common origin of high-order memory centers.

    Science.gov (United States)

    Maza, Francisco Javier; Sztarker, Julieta; Shkedy, Avishag; Peszano, Valeria Natacha; Locatelli, Fernando Federico; Delorenzi, Alejandro

    2016-12-06

    The hypothesis of a common origin for the high-order memory centers in bilateral animals is based on the evidence that several key features, including gene expression and neuronal network patterns, are shared across several phyla. Central to this hypothesis is the assumption that the arthropods' higher order neuropils of the forebrain [the mushroom bodies (MBs) of insects and the hemiellipsoid bodies (HBs) of crustaceans] are homologous structures. However, even though involvement in memory processes has been repeatedly demonstrated for the MBs, direct proof of such a role in HBs is lacking. Here, through neuroanatomical and immunohistochemical analysis, we identified, in the crab Neohelice granulata, HBs that resemble the calyxless MBs found in several insects. Using in vivo calcium imaging, we revealed training-dependent changes in neuronal responses of vertical and medial lobes of the HBs. These changes were stimulus-specific, and, like in the hippocampus and MBs, the changes reflected the context attribute of the memory trace, which has been envisioned as an essential feature for the HBs. The present study constitutes functional evidence in favor of a role for the HBs in memory processes, and provides key physiological evidence supporting a common origin of the arthropods' high-order memory centers.

  1. First laboratory insight on the behavioral rhythms of the bathyal crab Geryon longipes

    Science.gov (United States)

    Nuñez, J. D.; Sbragaglia, V.; García, J. A.; Company, J. B.; Aguzzi, J.

    2016-10-01

    The deep sea is the largest and at the same time least explored biome on Earth, but quantitative studies on the behavior of bathyal organisms are scarce because of the intrinsic difficulties related to in situ observations and maintaining animals in aquaria. In this study, we reported, for the first time, laboratory observations on locomotor rhythms and other behavioral observations (i.e. feeding, exploring and self-grooming) for the bathyal crab Geryon longipes. Crabs were collected on the middle-lower slope (720-1750 m) off the coast of Blanes (Spain). Inertial (18 h) water currents and monochromatic blue (i.e. 470 nm) light-darkness (24 h) cycles were simulated in two different experiments in flume tanks endowed with burrows. Both cycles were simulated in order to investigate activity rhythms regulation in Mediterranean deep-sea benthos. Crabs showed rhythmic locomotor activity synchronized to both water currents and light-darkness cycles. In general terms, feeding and exploring behaviors also followed the same pattern. Results presented here indicate the importance of local inertial (18 h) periodicity of water currents at the seabed as a temporal cue regulating the behavior of bathyal benthic fauna in all continental margin areas where the effects of tides is negligible.

  2. Are Crab nanoshots Schwinger sparks?

    Energy Technology Data Exchange (ETDEWEB)

    Stebbins, Albert [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Yoo, Hojin [Univ. of Wisconsin, Madison, WI (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)

    2015-05-21

    The highest brightness temperature ever observed are from "nanoshots" from the Crab pulsar which we argue could be the signature of bursts of vacuum e± pair production. If so this would be the first time the astronomical Schwinger effect has been observed. These "Schwinger sparks" would be an intermittent but extremely powerful, ~103 L, 10 PeV e± accelerator in the heart of the Crab. These nanosecond duration sparks are generated in a volume less than 1 m3 and the existence of such sparks has implications for the small scale structure of the magnetic field of young pulsars such as the Crab. As a result, this mechanism may also play a role in producing other enigmatic bright short radio transients such as fast radio bursts.

  3. Chemical induction in mangrove crab megalopae, Ucides cordatus (Ucididae): Do young recruits emit metamorphosis-triggering odours as do conspecific adults?

    Science.gov (United States)

    Simith, Darlan de Jesus de Brito; Abrunhosa, Fernando Araújo; Diele, Karen

    2013-10-01

    In many brachyuran species, including the mangrove crab Ucides cordatus, water-soluble chemicals (odours) emitted by adult residents trigger metamorphosis of megalopae, probably facilitating habitat selection and settlement near conspecific crab population. New field findings revealed that early benthic crab stages co-inhabit burrows of both juveniles and adults of U. cordatus which raised the question whether megalopae are also stimulated by sexually immature juveniles. Therefore, we tested in an experimental laboratory study the hypothesis that small benthic recruits and older juveniles also emit metamorphosis-stimulating odours as do conspecific adult crabs. U. cordatus megalopae were cultivated in eight conspecific odour-treatments containing seawater previously conditioned with crabs of different carapace widths (CW 0.15-5.0 cm) and in a control treatment with filtered seawater not conditioned with crabs. In all odour-treatments, including those with small immature crabs, the percentage of metamorphosed larvae was significantly higher (≥74%) and the average development was shorter (15.8-19.3 days) than in the control group, where only 30% moulted after 25.6 ± 6.6 days of megalopal development. In addition, megalopae developed 2.7 days faster when exposed to odours from young and older juveniles compared to those larvae kept in contact with odours from conspecific adults. Our results clearly demonstrate that the emission of metamorphic odours in U. cordatus is independent of size/age or sexual maturity. The responsiveness of megalopae to chemicals emitted by resident crabs of varying ages should aid the natural recovery of U. cordatus populations in areas significantly affected by size-selective fishery where only large conspecific adults are harvested.

  4. LHC crab-cavity aspects and strategy

    International Nuclear Information System (INIS)

    Calaga, R.; Tomas, R.; Zimmermann, F.

    2010-01-01

    The 3rd LHC Crab Cavity workshop (LHC-CC09) took place at CERN in October 2009. It reviewed the current status and identified a clear strategy towards a future crab-cavity implementation. Following the success of crab cavities in KEK-B and the strong potential for luminosity gain and leveling, CERN will pursue crab crossing for the LHC upgrade. We present a summary and outcome of the variousworkshop sessions which have led to the LHC crab-cavity strategy, covering topics like layout, cavity design, integration, machine protection, and a potential validation test in the SPS.

  5. Reproduction and management of the mangrove crab Ucides cordatus (Crustacea, Brachyura, Ucididae) at Iguape, São Paulo, Brazil.

    Science.gov (United States)

    Sant'Anna, Bruno S; Borges, Roberto P; Hattori, Gustavo Y; Pinheiro, Marcelo A A

    2014-09-01

    The mangrove crab Ucides cordatus is one of the most exploited crustaceans in Brazil. The present study investigated the breeding season of this species and the period of the "andada" phenomenon, when the crabs are active outside their burrows and perform agonistic behaviors. Furthermore related them to environmental factors, in a mangrove on the coast of Brazil, with inferences about management of this crab. The crabs reproduced from October through February. The "andada" occurred from November through February, with typical characteristics in the first two months, during the full and new moon periods, and was influenced positively by the air and soil temperature, luminosity, and tidal amplitude, and negatively by salinity. Based on the results of the present study, the period when the "andada" occurs in other parts of Brazil could be defined, which will aid in managing this fishery. For Iguape, state of São Paulo, Brazil, we suggest a legal off-season for both sexes in December or during the full and new moon, including January.

  6. Origin of tropical American burrowing reptiles by transatlantic rafting.

    Science.gov (United States)

    Vidal, Nicolas; Azvolinsky, Anna; Cruaud, Corinne; Hedges, S Blair

    2008-02-23

    Populations of terrestrial or freshwater taxa that are separated by oceans can be explained by either oceanic dispersal or fragmentation of a previously contiguous land mass. Amphisbaenians, the worm lizards (approx. 165 species), are small squamate reptiles that are uniquely adapted to a burrowing lifestyle and inhabit Africa, South America, Caribbean Islands, North America, Europe and the Middle East. All but a few species are limbless and they rarely leave their subterranean burrows. Given their peculiar habits, the distribution of amphisbaenians has been assumed to be primarily the result of two land-mass fragmentation events: the split of the supercontinent Pangaea starting 200 Myr ago, separating species on the northern land mass (Laurasia) from those on the southern land mass (Gondwana), and the split of South America from Africa 100 Myr ago. Here we show with molecular evidence that oceanic dispersal-on floating islands-played a more prominent role, and that amphisbaenians crossed the Atlantic Ocean in the Eocene (40 Myr ago) resulting in a tropical American radiation representing one-half of all known amphisbaenian species. Until now, only four or five transatlantic dispersal events were known in terrestrial vertebrates. Significantly, this is the first such dispersal event to involve a group that burrows, an unexpected lifestyle for an oceanic disperser.

  7. Mammalian mesocarnivore visitation at tortoise burrows in a wind farm

    Science.gov (United States)

    Agha, Mickey; Smith, Amanda L.; Lovich, Jeffrey E.; Delaney, David F.; Ennen, Joshua R.; Briggs, Jessica R.; Fleckenstein, Leo J.; Tennant, Laura A.; Puffer, Shellie R.; Walde, Andrew D.; Arundel, Terry; Price, Steven J.; Todd, Brian D.

    2017-01-01

    There is little information on predator–prey interactions in wind energy landscapes in North America, especially among terrestrial vertebrates. Here, we evaluated how proximity to roads and wind turbines affect mesocarnivore visitation with desert tortoises (Gopherus agassizii) and their burrows in a wind energy landscape. In 2013, we placed motion-sensor cameras facing the entrances of 46 active desert tortoise burrows in a 5.2-km2 wind energy facility near Palm Springs, California, USA. Cameras recorded images of 35 species of reptiles, mammals, and birds. Counts for 4 species of mesocarnivores at desert tortoise burrows increased closer to dirt roads, and decreased closer to wind turbines. Our results suggest that anthropogenic infrastructure associated with wind energy facilities could influence the general behavior of mammalian predators and their prey. Further investigation of proximate mechanisms that underlie road and wind turbine effects (i.e., ground vibrations, sound emission, and traffic volume) and on wind energy facility spatial designs (i.e., road and wind turbine configuration) could prove useful for better understanding wildlife responses to wind energy development. © 2017 The Wildlife Society.

  8. Does petroleum development affect burrowing owl nocturnal space-use?

    Energy Technology Data Exchange (ETDEWEB)

    Scobie, Corey; Wellicome, Troy; Bayne, Erin [Department of Biological Sciences, University of Alberta (Canada)], email: cscobie@ualberta.ca, email: tiw@ualberta.ca, email: bayne@ualberta.ca

    2011-07-01

    Decline all over Canada in the population of burrowing owls, a federally listed endangered species, has raised concerns about the possible influence of petroleum infrastructure development on owl nocturnal space-use while foraging. Roads, wells, pipelines and sound-producing facilities related to petroleum development change the landscape and can influence the owls' mortality risk. For 3 years, 27 breeding adult male burrowing owls with nests close to different petroleum infrastructures were captured and fitted with a miniature GPS datalogger in order to track their nocturnal foraging. Data from these GPS devices were fed into a geographical information system and showed that pipelines and wells did not alter the foraging habits of the owls. Dirt and gravel roads, with little traffic, were preferentially selected by the owls, conceivably because of higher owl mortality risk along paved roads. Sound-producing facilities did not change owls' foraging behaviour, implying that sound may not affect their nocturnal space-use. Traffic data and sound power measurements will be used in further studies in an effort to better understand burrowing owls' nocturnal foraging habits.

  9. Rodent burrows in late Pleistocene paleosols at Korean Palaeolithic sites and their implications for paleoclimate changes

    Science.gov (United States)

    Lim, H.; Park, S.; Lee, J.; Lee, Y.

    2013-12-01

    Rodent burrows are commonly found at many Paleolithic archaeological sites in Korea. They are nearly straight in horizontal view and gently inclined in lateral view. Burrow diameters are mostly 7 - 10cm, and burrow length may reach a few meters. Vertical penetration depths are generally about 1 m from the surface, and the thickness of the burrow-bearing layer is about 1-2 m. Although no remains (bones, teeth, claws, and coprolites) were found within burrows, they are interpreted to have been produced by rodent-like mammals (probably ground squirrels) based on the size and architecture. According to the previous study, the age of these burrows was constrained to be between ca. 40,000 and 25,000 yr BP by tephrochronology, radiocarbon and optically stimulated luminescence dating results (Lim et al., 2007). However, little is known about the reason why these burrows have disappeared after late Pleistocene time. For this question, two explanations can be considered: extinction or migration. Since same kinds of burrows are still found in the high-latitude regions, such as Mongolia and North America, the possibility of extinction can be ruled out. Therefore, migration seems to be the most likely explanation. Our results show that the destruction of habitat caused by climate change during this period is the main reason for the northward migration of burrowing animals. This study suggests that rodent burrows found in the late Pleistocene paleosols can provide useful information on paleoclimate and paleoenvironmental changes.

  10. Large mammal burrows in late Miocene calcic paleosols from central Argentina: paleoenvironment, taphonomy and producers

    Directory of Open Access Journals (Sweden)

    María Cristina Cardonatto

    2018-05-01

    Full Text Available Large cylindrical sediment-filled structures interpreted as mammal burrows occur within the loess-paleosol sequence of the late Miocene Cerro Azul Formation of central Argentina. A total of 115 burrow fills from three localities were measured. They are typically shallowly dipping, subcylindrical, unbranched structures with rounded ends and lacking enlargements. The horizontal diameter of the burrows range between 0.15 and 1.50 m, with most of the burrows in the interval of 0.39 to 0.98 m. Geometric morphometric analysis of transverse cross-sections support their distinct subcircular and elliptical (horizontally flattened shapes. Burrow fills are typically laminated in the lower part and massive in the upper part. The laminated intervals reflect pulses of flowing water entering the abandoned burrow during moderate rains, whereas massive intervals reflect mass flow input of dense sediment-water mixtures during heavy rains that produced sheet floods. Approximately 1% of the burrows contained fragmentary, disarticulated and weathered mammal bones that were introduced in the open burrow by currents along with other sedimentary particles. Analysis of the tetrapod burrow fossil record suggests that Miocene burrows, including those studied herein, reflect a remarkable increase in the average size of the fossorial fauna. We conclude that large late Miocene mammals dug burrows essentially as a shelter against environmental extremes and to escape predation. The simple architecture of the burrows suggests that the producers essentially foraged aboveground. Several mammal groups acquired fossorial habits in response to cold and seasonally dry climatic conditions that prevailed during the late Miocene in southern South America. The considerable range of horizontal diameters of the studied burrows can be attributed to a variety of producers, including dasypodids, the notoungulate Paedotherium minor, Glyptodontidae and Proscelidodon sp.

  11. Human threats to sandy beaches: A meta-analysis of ghost crabs illustrates global anthropogenic impacts.

    Science.gov (United States)

    Schlacher, Thomas A.; Lucrezi, Serena; Connolly, Rod M.; Peterson, Charles H.; Gilby, Ben L.; Maslo, Brooke; Olds, Andrew D.; Walker, Simon J.; Leon, Javier X.; Huijbers, Chantal M.; Weston, Michael A.; Turra, Alexander; Hyndes, Glenn A.; Holt, Rebecca A.; Schoeman, David S.

    2016-02-01

    Beach and coastal dune systems are increasingly subjected to a broad range of anthropogenic pressures that on many shorelines require significant conservation and mitigation interventions. But these interventions require reliable data on the severity and frequency of adverse ecological impacts. Such evidence is often obtained by measuring the response of 'indicator species'. Ghost crabs are the largest invertebrates inhabiting tropical and subtropical sandy shores and are frequently used to assess human impacts on ocean beaches. Here we present the first global meta-analysis of these impacts, and analyse the design properties and metrics of studies using ghost-crabs in their assessment. This was complemented by a gap analysis to identify thematic areas of anthropogenic pressures on sandy beach ecosystems that are under-represented in the published literature. Our meta-analysis demonstrates a broad geographic reach, encompassing studies on shores of the Pacific, Indian, and Atlantic Oceans, as well as the South China Sea. It also reveals what are, arguably, two major limitations: i) the near-universal use of proxies (i.e. burrow counts to estimate abundance) at the cost of directly measuring biological traits and bio-markers in the organism itself; and ii) descriptive or correlative study designs that rarely extend beyond a simple 'compare and contrast approach', and hence fail to identify the mechanistic cause(s) of observed contrasts. Evidence for a historically narrow range of assessed pressures (i.e., chiefly urbanisation, vehicles, beach nourishment, and recreation) is juxtaposed with rich opportunities for the broader integration of ghost crabs as a model taxon in studies of disturbance and impact assessments on ocean beaches. Tangible advances will most likely occur where ghost crabs provide foci for experiments that test specific hypotheses associated with effects of chemical, light and acoustic pollution, as well as the consequences of climate change (e

  12. Stomach fullness shapes prey choice decisions in crab plovers (Dromas ardeola)

    Science.gov (United States)

    Bom, Roeland A.; Fijen, Thijs P. M.; van Gils, Jan A.

    2018-01-01

    Foragers whose energy intake rate is constrained by search and handling time should, according to the contingency model (CM), select prey items whose profitability exceeds or equals the forager’s long-term average energy intake rate. This rule does not apply when prey items are found and ingested at a higher rate than the digestive system can process them. According to the digestive rate model (DRM), foragers in such situations should prefer prey with the highest digestive quality, instead of the highest profitability. As the digestive system fills up, the limiting constraint switches from ingestion rate to digestion rate, and prey choice is expected to change accordingly for foragers making decisions over a relative short time window. We use these models to understand prey choice in crab plovers (Dromas ardeola), preying on either small burrowing crabs that are swallowed whole (high profitability, but potentially inducing a digestive constraint) or on larger swimming crabs that are opened to consume only the flesh (low profitability, but easier to digest). To parameterize the CM and DRM, we measured energy content, ballast mass and handling times for different sized prey, and the birds’ digestive capacity in three captive individuals. Subsequently, these birds were used in ad libitum experiments to test if they obeyed the rules of the CM or DRM. We found that crab plovers with an empty stomach mainly chose the most profitable prey, matching the CM. When stomach fullness increased, the birds switched their preference from the most profitable prey to the highest-quality prey, matching the predictions of the DRM. This shows that prey choice is context dependent, affected by the stomach fullness of an animal. Our results suggest that prey choice experiments should be carefully interpreted, especially under captive conditions as foragers often ‘fill up’ in the course of feeding trials. PMID:29641542

  13. AFSC/RACE/SAP/Jensen: Bitter crab disease mortality in SE Alaska Tanner crab

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These are data from a laboratory experiment in which wild caught male Tanner crab (Chionoecetes bairdi) from Stephens Passage, SE Alaska were held to evaluate crab...

  14. The Crab pulsar at VHE

    Directory of Open Access Journals (Sweden)

    Zanin Roberta

    2017-01-01

    Full Text Available The last six years have witnessed major revisions of our knowledge about the Crab Pulsar. The consensus scenario for the origin of the high-energy pulsed emission has been challenged with the discovery of a very-high-energy power law tail extending up to ~400 GeV, above the expected spectral cut off at a few GeV. Now, new measurements obtained by the MAGIC collaboration extend the energy spectrum of the Crab Pulsar even further, on the TeV regime. Above ~400 GeV the pulsed emission comes mainly from the interpulse, which becomes more prominent with energy due to a harder spectral index. These findings require γ -ray production via inverse Compton scattering close to or beyond the light cylinder radius by an underlying particle population with Lorentz factors greater than 5 × 106. We will present those new results and discuss the implications in our current knowledge concerning pulsar environments.

  15. Population biology of the crab Armases angustipes (Crustacea, Decapoda, Sesarmidae at Brazilian tropical coast

    Directory of Open Access Journals (Sweden)

    Marina de Sá Leitão C. de Araújo

    2014-06-01

    Full Text Available The semi terrestrial crabs are important elements of the fauna of coastal regions. The aim of this study was to analyze the population structure of Armases angustipes (Dana, 1852 at estuaries of the Ariquindá River, considered a non impacted area, and Mamucabas River, considered a few impacted area, on the south coast of state of Pernambuco, Brazil. The species occurred in all months of the year. The number of individuals per month varied, being higher in the months of transition between the seasons. This is probably due to significant seasonal variations of air and burrow temperature and burrow salinity. There was no sexual dimorphism in size of A. angustipes in the mangrove of Ariquindá River, but males were larger than females in the mangrove of Mamucabas River. In both estuaries, the sex ratio did not differ from Mendelian proportion, but showed a deviation for females. The analysis of temporal variation in sex ratio showed significant differences in some months of the year. These variations are due to cyclical events that act distinctly on each sex. In both estuaries, size classes of carapace width were equally represented by both sexes. The ovigerous females of A. angustipes occurred only in some months of the year, especially in summer, in both estuaries. Probably the high phytoplankton productivity observed in summer favors the reproductive activity, since these algae serve as food for the larvae. Specimens of the population of Rio Ariquindá are largest and wider than those of Mamucabas River. This fact, associated with the low abundance of crabs and the lower frequency of ovigerous females observed in Mamucabas River, is an indication that this population may be influenced by the environmental impacts that this estuary has received.

  16. The Crab Nebula flaring activity

    Energy Technology Data Exchange (ETDEWEB)

    Montani, G., E-mail: giovanni.montani@frascati.enea.it [ENEA – C.R, UTFUS-MAG, via Enrico Fermi 45, I-00044 Frascati (RM) (Italy); Dipartimento di Fisica, Università di Roma “Sapienza”, p.le Aldo Moro 5, I-00185 Roma (Italy); Bernardini, M.G. [INAF – Osservatorio Astronomico di Brera, via Bianchi 46, I-23807 Merate (Italy)

    2014-12-12

    The discovery made by AGILE and Fermi of a short time scale flaring activity in the gamma-ray energy emission of the Crab Nebula is a puzzling and unexpected feature, challenging particle acceleration theory. In the present work we propose the shock-induced magnetic reconnection as a viable mechanism to explain the Crab flares. We postulate that the emitting region is located at ∼10{sup 15} cm from the central pulsar, well inside the termination shock, which is exactly the emitting region size as estimated by the overall duration of the phenomenon ∼1 day. We find that this location corresponds to the radial distance at which the shock-induced magnetic reconnection process is able to accelerate the electrons up to a Lorentz factor ∼10{sup 9}, as required by the spectral fit of the observed Crab flare spectrum. The main merit of the present analysis is to highlight the relation between the observational constraints to the flare emission and the radius at which the reconnection can trigger the required Lorentz factor. We also discuss different scenarios that can induce the reconnection. We conclude that the existence of a plasma instability affecting the wind itself as the Weibel instability is the privileged scenario in our framework.

  17. Artificially evolved functional shell morphology of burrowing bivalves

    DEFF Research Database (Denmark)

    Germann, D. P.; Schatz, W.; Hotz, Peter Eggenberger

    2014-01-01

    dimensional (3D) objects, the first ever artificial evolution of a physical bivalve shell was performed. The result was a vertically flattened shell occupying only the top sediment layers. Insufficient control of the sediment was the major limitation of the setup and restricted the significance of the results......, there are almost no studies experimentally testing their dynamic properties. To investigate the functional morphology of the bivalve shell, we employed a synthetic methodology and built an experimental setup to simulate the burrowing process. Using an evolutionary algorithm and a printer that prints three...

  18. Artificially evolved functional shell morphology of burrowing bivalves

    DEFF Research Database (Denmark)

    Germann, D. P.; Schatz, W.; Hotz, Peter Eggenberger

    2014-01-01

    The morphological evolution of bivalves is documented by a rich fossil record. It is believed that the shell shape and surface sculpture play an important role for the burrowing performance of endobenthic species. While detailed morphometric studies of bivalve shells have been done...... dimensional (3D) objects, the first ever artificial evolution of a physical bivalve shell was performed. The result was a vertically flattened shell occupying only the top sediment layers. Insufficient control of the sediment was the major limitation of the setup and restricted the significance of the results...

  19. Particle beam and crabbing and deflecting structure

    Science.gov (United States)

    Delayen, Jean [Yorktown, VA

    2011-02-08

    A new type of structure for the deflection and crabbing of particle bunches in particle accelerators comprising a number of parallel transverse electromagnetic (TEM)-resonant) lines operating in opposite phase from each other. Such a structure is significantly more compact than conventional crabbing cavities operating the transverse magnetic TM mode, thus allowing low frequency designs.

  20. Preservation of crab meat by gamma irradiation

    International Nuclear Information System (INIS)

    Loaharanu, P.; Prompubesara, C.; Kraisorn, K.; Noochpramool, K.

    1972-01-01

    Fresh crab meat from swimming crab (Portunus pelagicus, Linn.) was irradiated at doses of 0.075, 0.15 and 0.25 Mrad and held at 3 0 C. The storage life of non-irradiated crab meat was approximately 7 days compared with 14 days for crab meat irradiated at 0.075 Mrad and 28 days for samples receiving 0.15 or 0.25 Mrad treatment. Total aerobic count, trimethylamine nitrogen, total volatile basic nitrogen, and ammonia contents were used as objective indices of freshness in comparison with sensory evaluation of the crab meat. All objective indices correlated well with the sensory judgement of the samples. The crab meat used in the study was heavily contaminated with microorganisms. Irradiation at 0.15 and 0.25 Mrad reduced approximately 2 log cycles in the total count. Acinetobacter (Achromobacter) was predominated in irradiated crab meat, especially after prolonged storage. High coagulase positive staphylococci count was detected in only non-irradiated crab meat

  1. The Crab Boat Engineering Design Challenge

    Science.gov (United States)

    Love, Tyler S.; Ryan, Larry

    2017-01-01

    Crab cakes and football, that's what Maryland does!" (Abrams, Levy, Panay, & Dobkin, 2005). Although the Old Line State is notorious for harvesting delectable blue crabs, the movie "Wedding Crashers" failed to highlight something else Maryland does well: engineering design competitions. This article discusses how a multistate…

  2. Study on irradiation treatment to drunk crab

    International Nuclear Information System (INIS)

    Cao Hong; Chen Xiulan; Zhai Jianqing; Bao Jianzhong; Wang Jinrong

    2002-01-01

    For guaranteeing the quality of irradiated drunk crab, manufacture method of the dosimeter, sample setting and taking position, irradiation time, asymmetry degree of irradiation dose, contrast of the dosimeter are discussed and some reference datum to commercialization of drunk crab's irradiation are provided

  3. Sand moisture as a factor determining depth of burrowing in the ...

    African Journals Online (AJOL)

    Tylos granulatus, a sandy-beach isopod, prefers an environmental moisture range exceeding 3,4% but less than 13%. The depths to which the animals burrow are, at least partly, determined by the moisture gradient in the sand. They are, however, incapable of burrowing into lotally dry sand. Animals alter their position in ...

  4. Aardvark burrows: a potential resource for animals in arid and semi ...

    African Journals Online (AJOL)

    Twenty-seven vertebrate species (21 mammals, two birds, three reptiles and one amphibian) were recorded making use of the burrows and it is likely that these species accrue benefits (e.g. a buffered microclimate) from burrow use. However, our sampling was biased towards mammals and nocturnal species. Consequently ...

  5. COMPARISON OF CARBON AND NITROGEN FLUXES IN TIDEFLAT FOOD WEBS DOMINATED BY BURROWING SHRIMP OR BY CULTURED OYSTERS

    Science.gov (United States)

    Two species of indigenous, thalassinid burrowing shrimps are pests to the benthic culture of Pacific oysters (Crassostrea gigas) because deposition of sediment excavated by the shrimps buries or smothers the oysters. Carbaryl pesticide is used to reduce burrowing shrimp densitie...

  6. Burrowing behavior as an indicator of post-laparotomy pain in mice

    Directory of Open Access Journals (Sweden)

    Paulin Jirkof

    2010-10-01

    Full Text Available Detection of persistent pain of a mild-to-moderate degree in laboratory mice is difficult because mice do not show unambiguous symptoms of pain or suffering using standard methods of short-term observational or clinical monitoring. This study investigated the potential use of burrowing performance — a spontaneous and highly motivated behavior — as a measure of post-operative pain in laboratory mice. The influence of minor surgery on burrowing was investigated in adult C57BL/6J mice of both genders in a modified rodent burrowing test (displacement of food pellets from a pellet-filled tube within the animal’s home cage. Almost all (98% healthy mice burrowed (mean latency 1.3 h, SEM 0.5 h. After surgery without pain treatment, latency of burrowing was significantly prolonged (mean ∆ latency 10 h. Analgesic treatment using the anti-inflammatory drug carprofen (5 mg/kg bodyweight decreased latency of burrowing after surgery (mean ∆ latency 5.5 h to the level found in mice that had been anaesthetised (mean ∆ latency 5.3 h or had received anaesthesia and analgesia (mean ∆ latency 4.6 h. Analgesia during surgery was associated with a significantly earlier onset of burrowing compared to surgery without pain treatment. A distinct gradation in burrowing performance was found ranging from the undisturbed pre-operative status to the intermediate level following anaesthesia/analgesia and surgery with analgesia, to the pronounced prolongation of latency to burrow after surgery without pain relief. In conclusion, post-surgical impairment of general condition, probably mainly attributable to pain, can be conveniently assessed in laboratory mice on the basis of the burrowing test.

  7. Sterilizing effect of irradiation processing on drunk crab

    International Nuclear Information System (INIS)

    Chen Xiulan; Shen Qingkang; Bao Jianzhong; Cao Hong; Zhang Yongtai; Han Yuepeng

    2001-01-01

    Drunk crab is a kind of specially processed crab food with the shelf time of 3 months when stored at low temperature of l to 5℃. The shelf time of the tin paked drunk crab can be extend to 9 months when the crab food is irradiated by "6"0Co-γ rays with the dosage of 2 ∼ 8 k Gy. The irradiation processing technology will make drunk crab be supplied the whole year. (authors)

  8. Priming effect in topsoil and subsoil induced by earthworm burrows

    Science.gov (United States)

    Thu, Duyen Hoang Thi

    2017-04-01

    Earthworms (Lumbricus terrestris L.) not only affect soil physics, but they also boost microbial activities and consequently important hotspots of microbial mediated carbon and C turnover through their burrowing activity. However, it is still unknown to which extend earthworms affect priming effect in top- and subsoil horizons. More labile C inputs in earthworm burrows were hypothesized to trigger higher priming of soil organic matter (SOM) decomposition compared to rhizosphere and bulk soil. Moreover, this effect was expected to be more pronounced in subsoil due to its greater C and nutrient limitation. To test these hypotheses, biopores and bulk soil were sampled from topsoil (0-30 cm) and two subsoil depths (45-75 and 75-105 cm). Additionally, rhizosphere samples were taken from the topsoil. Total organic C (Corg), total N (TN), total P (TP) and enzyme activities involved in C-, N-, and P-cycling (cellobiohydrolase, β-glucosidase, xylanase, chitinase, leucine aminopeptidase and phosphatase) were measured. Priming effects were calculated as the difference in SOM-derived CO2 from soil with or without 14C-labelled glucose addition. Enzyme activities in biopores were positively correlated with Corg, TN and TP, but in bulk soil this correlation was negative. The more frequent fresh and labile C inputs to biopores caused 4 to 20 time higher absolute priming of SOM turnover due to enzyme activities that were one order of magnitude higher than in bulk soil. In subsoil biopores, reduced labile C inputs and lower N availability stimulated priming twofold greater than in topsoil. In contrast, a positive priming effect in bulk soil was only detected at 75-105 cm depth. We conclude that earthworm burrows provide not only the linkage between top- and subsoil for C and nutrients, but strongly increase microbial activities and accelerate SOM turnover in subsoil, contributing to nutrient mobilization for roots and CO2 emission increase as a greenhouse gas. Additionally, the

  9. Spilled oil and infaunal activity - Modification of burrowing behavior and redistribution of oil

    Science.gov (United States)

    Clifton, H.E.; Kvenvolden, K.A.; Rapp, J.B.

    1984-01-01

    A series of experiments in Willapa Bay, Washington, indicates the degree to which the presence of spilled oil modifies the burrowing behavior of infauna and the extent to which the animals redistribute oil into intertidal sediment. Small amounts of North Slope crude oil introduced at low tide directly into burrow openings (mostly made by the crustacean Callianassa) resulted in a limited and temporary reduction in the number of burrow openings. In contrast, a layer of oil-saturated sand 1 cm thick buried about 5 cm below the sediment surface sharply reduced the number of burrow openings. After a year, the few new burrows penetrated only the margins of the experimental plot, and bioturbation below the buried oil-saturated sand layer declined dramatically. The experiments suggest that small amounts of oil temporarily stranded by tides in themselves have no long-range effect on burrowing behavior. The fauna, however, are capable of introducing measurable amounts of oil into the subsurface, where it is retained long after the rest of the stranded oil had washed away. A buried layer of oil-saturated sand greatly reduces infaunal activity; the oil presents an effective barrier that can persist for years. The oil incorporated into the sediment from burrow openings showed evidence of degradation after 7 months. In contrast the layer of buried oil remained essentially undergraded after a period of two years, even though oil in lower concentrations above the layer was degraded after a period of one year. This variation in degree of degradation of the buried oil, as well as the heterogeneity of oil distribution wherever the oil has been incorporated from the surface, emphasises the importance of careful sampling in any attempt to locate or monitor the presence of spilled oil in the substrate.In a series of experiments in Willapa Bay, Washington, small amounts of North Slope crude oil introduced at low tide directly into burrow openings resulted in a limited and temporary

  10. A large bubble around the Crab Nebula

    Science.gov (United States)

    Romani, Roger W.; Reach, William T.; Koo, Bon Chul; Heiles, Carl

    1990-01-01

    IRAS and 21 cm observations of the interstellar medium around the Crab nebula show evidence of a large bubble surrounded by a partial shell. If located at the canonical 2 kpc distance of the Crab pulsar, the shell is estimated to have a radius of about 90 pc and to contain about 50,000 solar masses of swept-up gas. The way in which interior conditions of this bubble can have important implications for observations of the Crab are described, and the fashion in which presupernova evolution of the pulsar progenitor has affected its local environment is described.

  11. Final focus designs for crab waist colliders

    Directory of Open Access Journals (Sweden)

    A. Bogomyagkov

    2016-12-01

    Full Text Available The crab waist collision scheme promises significant luminosity gain. The successful upgrade of the DAΦNE collider proved the principle of crab waist collision and increased luminosity 3 times. Therefore, several new projects try to implement the scheme. The paper reviews interaction region designs with the crab waist collision scheme for already existent collider DAΦNE and SuperKEKB, presently undergoing commissioning, for the projects of SuperB in Italy, CTau in Novosibirsk and FCC-ee at CERN.

  12. The influence of small mammal burrowing activity on water storage at the Hanford Site

    International Nuclear Information System (INIS)

    Landeen, D.S.

    1994-09-01

    The amount and rate at which water may penetrate a protective barrier and come into contact with buried radioactive waste is a major concern. Because burrowing animals eventually will reside on the surface of any protective barrier, the effect these burrow systems may have on the loss or retention of water needs to be determined. The first section of this document summarizes the known literature relative to small mammals and the effects that burrowing activities have on water distribution, infiltration, and the overall impact of burrows on the ecosystem. Topics that are summarized include burrow air pressures, airflow, burrow humidity, microtopography, mounding, infiltration, climate, soil evaporation, and discussions of large pores relative to water distribution. The second section of this document provides the results of the study that was conducted at the Hanford Site to determine what effect small mammal burrows have on water storage. This Biointrusion task is identified in the Permanent Isolation Surface Barrier Development Plan in support of protective barriers. This particular animal intrusion task is one part of the overall animal intrusion task identified in Animal Intrusion Test Plan

  13. Large-Diameter Burrows of the Triassic Ischigualasto Basin, NW Argentina: Paleoecological and Paleoenvironmental Implications

    Science.gov (United States)

    Colombi, Carina E.; Fernández, Eliana; Currie, Brian S.; Alcober, Oscar A.; Martínez, Ricardo; Correa, Gustavo

    2012-01-01

    Large-diameter ichnofossils comprising three morphotypes have been identified in the Upper Triassic Ischigualasto and Los Colorados formations of northwestern Argentina. These burrows add to the global record of the early appearance of fossorial behavior during early Mesozoic time. Morphotypes 1 and 2 are characterized by a network of tunnels and shafts that can be assigned to tetrapod burrows given similarities with previously described forms. However, differences in diameter, overall morphology, and stratigraphic occurrence allow their independent classification. Morphotype 3 forms a complex network of straight branches that intersect at oblique angles. Their calcareous composition and surface morphology indicate these structures have a composite biogenic origin likely developed due to combined plant/animal interactions. The association of Morphotypes 1 and 2 with fluvial overbank lithologies deposited under an extremely seasonal arid climate confirms interpretations that the early appearance of burrowing behavior was employed by vertebrates in response to both temperature and moisture-stress associated with seasonally or perpetually dry Pangean paleoclimates. Comparisons of burrow morphology and biomechanical attributes of the abundant paleovertebrate fauna preserved in both formations permit interpretations regarding the possible burrow architects for Morphotypes 1 and 2. In the case of the Morphotype 1, the burrow constructor could be one of the small carnivorous cynodonts, Ecteninion or Probelesodon. Assigning an architect for Morphotype 2 is more problematic due to mismatches between the observed burrow morphology and the size of the known Los Colorados vertebrates. PMID:23227195

  14. Synchrotron Reveals Early Triassic Odd Couple: Injured Amphibian and Aestivating Therapsid Share Burrow.

    Directory of Open Access Journals (Sweden)

    Vincent Fernandez

    Full Text Available Fossorialism is a beneficial adaptation for brooding, predator avoidance and protection from extreme climate. The abundance of fossilised burrow casts from the Early Triassic of southern Africa is viewed as a behavioural response by many tetrapods to the harsh conditions following the Permo-Triassic mass-extinction event. However, scarcity of vertebrate remains associated with these burrows leaves many ecological questions unanswered. Synchrotron scanning of a lithified burrow cast from the Early Triassic of the Karoo unveiled a unique mixed-species association: an injured temnospondyl amphibian (Broomistega that sheltered in a burrow occupied by an aestivating therapsid (Thrinaxodon. The discovery of this rare rhinesuchid represents the first occurrence in the fossil record of a temnospondyl in a burrow. The amphibian skeleton shows signs of a crushing trauma with partially healed fractures on several consecutive ribs. The presence of a relatively large intruder in what is interpreted to be a Thrinaxodon burrow implies that the therapsid tolerated the amphibian's presence. Among possible explanations for such unlikely cohabitation, Thrinaxodon aestivation is most plausible, an interpretation supported by the numerous Thrinaxodon specimens fossilised in curled-up postures. Recent advances in synchrotron imaging have enabled visualization of the contents of burrow casts, thus providing a novel tool to elucidate not only anatomy but also ecology and biology of ancient tetrapods.

  15. Burrow characteristics and habitat associations of armadillos in Brazil and the United States of America

    OpenAIRE

    Colleen M. McDonough; Michael J. DeLaney; Phu Quoc Le; Mark S. Blackmore; W. J. Loughry

    2000-01-01

    We censused and measured armadillo burrows in ten 10 m x 40 m plots in each of four habitat types at a study site in northern Florida and one in the Atlantic coastal rainforest of Brazil. The nine-banded armadillo (Dasypus novemcinctus) was the only species of armadillo found in Florida, but several additional species were present in Brazil. Burrows were more numerous but smaller in Brazil than in the U. S., probably due to the inclusion of burrows dug by the smaller congener D. septemcinctus...

  16. Observations on burrowing rates and comments on host specificity in the endangered mussel Lampsilis higginsi

    Science.gov (United States)

    Sylvester, J.R.; Holland, L.E.; Kamer, T.K.

    1984-01-01

    In preliminary laboratory studies, the endangered mussel Lampsilis higginsi was unable to burrow into rocky substrates, but did burrow into substrates comprised of silt, clay, sand, and/or pebble-gravel. Burrowing times were shortest in silt and longest in pebble-gravel. As judged by longevity of glochidial infection, walleye (Stizostedion vitreum) and largemouth bass (Micropterus salmoides) may be suitable hosts for the parasitic stage. When glochidia were placed in water without host fish, half had died after 48 hours, and all had died after 72 hours. (DBO).

  17. Monitoring the Crab Nebula with LOFT

    Science.gov (United States)

    Wilson-Hodge, Colleen A.

    2012-01-01

    From 2008-2010, the Crab Nebula was found to decline by 7% in the 15-50 keV band, consistently in Fermi GBM, INTEGRAL IBIS, SPI, and JEMX, RXTE PCA, and Swift BAT. From 2001-2010, the 15-50 keV flux from the Crab Nebula typically varied by about 3.5% per year. Analysis of RXTE PCA data suggests possible spectral variations correlated with the flux variations. I will present estimates of the LOFT sensitivity to these variations. Prior to 2001 and since 2010, the observed flux variations have been much smaller. Monitoring the Crab with the LOFT WFM and LAD will provide precise measurements of flux variations in the Crab Nebula if it undergoes a similarly active episode.

  18. Dominance and population structure of freshwater crabs ...

    African Journals Online (AJOL)

    1997-02-06

    Feb 6, 1997 ... Intraspecific aggression, predation and refuge availability are probable strong selection pressures in determining ... Hluhluwe Game Reserve, P.O. Box 25, 3935 .... video recorder in order not to disturb the crabs during obser-.

  19. Epizoic and ectoparasitic protozoans from crab larvae

    Digital Repository Service at National Institute of Oceanography (India)

    Santhakumari, V.

    A suctorian, Ephelota gemmipara Hertwig, infesting the zoea of the peacrab, Porcellana and an ectoparasitic flagellate Ellobiopsis chattoni Caullery infecting the zoea of the crab were observed from off Cape Comorin, the south-east coast of India...

  20. WAKEFIELD DAMPING FOR THE CLIC CRAB CAVITY

    CERN Document Server

    Ambattu, P; Dexter, A; Carter, R; Khan, V; Jones, R; Dolgashev, V

    2009-01-01

    A crab cavity is required in the CLIC to allow effective head-on collision of bunches at the IP. A high operating frequency is preferred as the deflection voltage required for a given rotation angle and the RF phase tolerance for a crab cavity are inversely proportional to the operating frequency. The short bunch spacing of the CLIC scheme and the high sensitivity of the crab cavity to dipole kicks demand very high damping of the inter-bunch wakes, the major contributor to the luminosity loss of colliding bunches. This paper investigates the nature of the wakefields in the CLIC crab cavity and the possibility of using various damping schemes to suppress them effectively.

  1. The anatomy of the king crab Hapalogaster mertensii Brandt, 1850 (Anomura: Paguroidea: Hapalogastridae): new insights into the evolutionary transformation of hermit crabs into king crabs

    NARCIS (Netherlands)

    Keiler, J.; Richter, S.; Wirkner, C.S.

    2015-01-01

    The emergence of king crabs from a hermit crab-like ancestor is one of the most curious events in decapod evolution. King crabs comprise two taxa, Lithodidae and Hapalogastridae, and while lithodids have formed the focus of various anatomical studies, the internal anatomy of hapalogastrids has never

  2. Behavioural adaptations to moisture as an environmental constraint in a nocturnal burrow-inhabiting Kalahari detritivore Parastizopus armaticeps Peringuey (Coleoptera: Tenebrionidae

    Directory of Open Access Journals (Sweden)

    O.A.E. Rasa

    1994-08-01

    Full Text Available The nocturnal desert detritivore Parastiz.opus armaticeps shows differences in surface activity patterns and burrow fidelity depending on surface humidity. After rain approximately half of the beetle population, independent of sex, is highly vagile and disperses over long distances. During drought, beetles are more sedentary and show higher burrow fidelity. They also inhabit burrows that are longer and deeper than non-inhabited ones, such burrows being relatively scarce. Burrow fidelity and the adoption of a more sedentary habit during drought are considered strategies to avoid the risks of not locating a suitable burrow before sunrise and subsequent desiccation in shallow burrows.

  3. Crabs

    Digital Repository Service at National Institute of Oceanography (India)

    Chatterji, A.

    stream_size 2 stream_content_type text/plain stream_name Biodiversity_Western_Ghats_Inf_Kit_1994_3.6_1.pdf.txt stream_source_info Biodiversity_Western_Ghats_Inf_Kit_1994_3.6_1.pdf.txt Content-Encoding ISO-8859-1 Content-Type text...

  4. Convolutional neural network guided blue crab knuckle detection for autonomous crab meat picking machine

    Science.gov (United States)

    Wang, Dongyi; Vinson, Robert; Holmes, Maxwell; Seibel, Gary; Tao, Yang

    2018-04-01

    The Atlantic blue crab is among the highest-valued seafood found in the American Eastern Seaboard. Currently, the crab processing industry is highly dependent on manual labor. However, there is great potential for vision-guided intelligent machines to automate the meat picking process. Studies show that the back-fin knuckles are robust features containing information about a crab's size, orientation, and the position of the crab's meat compartments. Our studies also make it clear that detecting the knuckles reliably in images is challenging due to the knuckle's small size, anomalous shape, and similarity to joints in the legs and claws. An accurate and reliable computer vision algorithm was proposed to detect the crab's back-fin knuckles in digital images. Convolutional neural networks (CNNs) can localize rough knuckle positions with 97.67% accuracy, transforming a global detection problem into a local detection problem. Compared to the rough localization based on human experience or other machine learning classification methods, the CNN shows the best localization results. In the rough knuckle position, a k-means clustering method is able to further extract the exact knuckle positions based on the back-fin knuckle color features. The exact knuckle position can help us to generate a crab cutline in XY plane using a template matching method. This is a pioneering research project in crab image analysis and offers advanced machine intelligence for automated crab processing.

  5. 50 CFR Table 7 to Part 680 - Initial Issuance of Crab QS by Crab QS Fishery

    Science.gov (United States)

    2010-10-01

    ... June 10, 2002 in the Eastern Aleutian Island golden (brown) king crab, Western Aleutian Island golden... through February 8, 2002. 4 years 3. Eastern Aleutian Islands golden king crab (EAG) 5 years of the 5-year... through September 24, 2000. (3) August 15, 2001 through September 10, 2001. 5 years 4. Eastern Bering Sea...

  6. Foraging behavior of the mangrove sesarmid crab Neosarmatium trispinosum enhances food intake and nutrient retention in a low-quality food environment

    Science.gov (United States)

    Harada, Yota; Lee, S. Y.

    2016-06-01

    The large sesarmid crab Neosarmatium trispinosum has been reported to actively collect freshly fallen mangrove leaves and store them in its burrow where they are assumed to age prior to consumption. This leaf-catching behavior was hypothesized to improve the palatability and nutritional quality of leaves through leaching of feeding deterrent and microbial enrichment during storage. Earlier studies also hypothesized that N. trispinosum feeds on sediment or animal material to meet their N needs. A series of experiments was carried out to investigate the foraging behavior of N. trispinosum against these hypotheses. Study of foraging behavior using remotely operated cameras indicated that this crab spends the far majority of time (97.5 ± 2.5%, SD) underground and only a small percentage of time outside its burrow foraging (2.2 ± 2.3%). Collection of fresh mangrove litter was swift but no record of predation was evident over 31 h of video records. A field leaf tethering experiment showed that this crab started to consume the leaves immediately after collection rather than storing whole leaves, refuting the leaf-aging hypothesis. N. trispinosum also showed a preference for senescent yellow leaves over decaying brown leaves. This behavior may only aim to stock leaves (i.e. to ensure food availability) rather than conditioning them through decay (i.e. to improve food quality). Analysis of gut contents showed that vascular plant material was the dominant food item (83.3 ± 4.6%), followed by sediment (9.2 ± 4.6%) but no animal materials were recorded. N. trispinosum therefore relies minimally on animal food but are capable of removing 50% of the daily leaf litter production. Elemental C, N analysis shows that sediment inside the burrow is a sufficient potential food source (C/N = 13 to 15). While having a lower C/N ratio than fresh green or yellow leaves, the N content of sediment (∼0.1%) was significantly lower than those of mangrove leaves (0.3-0.9%), and may thus

  7. Genetic characterization of the burrowing shrimp (Neotrypaea californiensis) in Washington and Oregon estuaries

    Science.gov (United States)

    The Ghost shrimp, (Neotrypaea californiensis) are burrowers, which have a wide demographic distribution along the United States Pacific Coast. Our study used genetic analysis to estimate the source populations of larvae recruiting into estuaries to allow a greater understanding ...

  8. Mechanics and Energetics of Excavation by Burrowing Wolf Spiders, Geolycosa spp.

    Science.gov (United States)

    Suter, Robert B.; Stratton, Gail E.; Miller, Patricia R.

    2011-01-01

    Burrowing wolf spiders, Geolycosa sp. (Araneae:Lycosidae), excavate vertical burrows and inhabit them throughout their lives or, in the case of males, until they mature and wander in search of mates. Three species: G. fatifera Kurata, G. missouriensis Banks, and G. rogersi Wallace were studied to understand how and at what expense the burrowing is accomplished. Normal and high-speed videography coupled with scanning electron microscopy revealed (a) that the convex surfaces of the two fangs, together, constitute the digging tool, (b) that boluses of soil are transported to the burrow entrance on the anterior surfaces of the chelicerae held there by the pedipalps, and (c) that each bolus is either incorporated into the growing turret or flung away, propelled by the forelegs. To elucidate the energetics of burrow construction, burrow volumes were calculated and then the costs associated with dislodging, elevating, and throwing the known volumes of soil were measured. A typical Geolycosa burrow, at a volume of 23.6 ± 2.0 ml and a depth of 13.2 ± 0.7 cm, required the removal of 918 boluses each weighing about 34 mg. The aggregate dislodging cost was close to 1.9 Joules in sand/sandy loam and 5.6 J in clayey subsoil, the work against gravity necessary to raise all of the boluses to the surface was about 0.13 J, and the aggregate cost of flinging the boluses was close to 0.014 J. Assuming that the ratio of external work to metabolic cost of external work is between 0.20 and 0.25 in spiders, the real cost of burrow construction would be between 8 J and 29 J, depending primarily on soil type. This is a small but not negligible cost when placed in the context of reproductive effort: a single Geolycosa egg, dozens to hundreds of which are produced in a clutch, contains about 10 J. PMID:21529154

  9. Perceptions of environmental changes and Lethargic crab disease among crab harvesters in a Brazilian coastal community

    Science.gov (United States)

    2011-01-01

    Background Lethargic Crab Disease (LCD) has caused significant mortalities in the population of Ucides cordatus crabs in the Mucuri estuary in Bahia State, Brazil, and has brought social and economic problems to many crab-harvesting communities that depend on this natural resource. The present work examined the perceptions of members of a Brazilian crab harvesting community concerning environmental changes and the Lethargic Crab Disease. Methods Field work was undertaken during the period between January and April/2009, with weekly or biweekly field excursions during which open and semi-structured interviews were held with local residents in the municipality of Mucuri, Bahia State, Brazil. A total of 23 individuals were interviewed, all of whom had at least 20 years of crab-collecting experience in the study region. Key-informants (more experienced crab harvesters) were selected among the interviewees using the "native specialist" criterion. Results According to the collectors, LCD reached the Mucuri mangroves between 2004 and 2005, decimating almost all crab population in the area, and in 2007, 2008 and 2009 high mortalities of U. cordatus were again observed as a result of recurrences of this disease in the region. In addition to LCD, crabs were also suffering great stock reductions due to habitat degradation caused by deforestation, landfills, sewage effluents, domestic and industrial wastes and the introduction of exotic fish in the Mucuri River estuary. The harvesting community was found to have significant ecological knowledge about the functioning of mangrove swamp ecology, the biology of crabs, and the mass mortality that directly affected the economy of this community, and this information was largely in accordance with scientific knowledge. Conclusions The study of traditional knowledge makes it possible to better understand human interactions with the environment and aids in the elaboration of appropriate strategies for natural resource conservation

  10. Perceptions of environmental changes and Lethargic crab disease among crab harvesters in a Brazilian coastal community

    Directory of Open Access Journals (Sweden)

    Firmo Angélica MS

    2011-11-01

    Full Text Available Abstract Background Lethargic Crab Disease (LCD has caused significant mortalities in the population of Ucides cordatus crabs in the Mucuri estuary in Bahia State, Brazil, and has brought social and economic problems to many crab-harvesting communities that depend on this natural resource. The present work examined the perceptions of members of a Brazilian crab harvesting community concerning environmental changes and the Lethargic Crab Disease. Methods Field work was undertaken during the period between January and April/2009, with weekly or biweekly field excursions during which open and semi-structured interviews were held with local residents in the municipality of Mucuri, Bahia State, Brazil. A total of 23 individuals were interviewed, all of whom had at least 20 years of crab-collecting experience in the study region. Key-informants (more experienced crab harvesters were selected among the interviewees using the "native specialist" criterion. Results According to the collectors, LCD reached the Mucuri mangroves between 2004 and 2005, decimating almost all crab population in the area, and in 2007, 2008 and 2009 high mortalities of U. cordatus were again observed as a result of recurrences of this disease in the region. In addition to LCD, crabs were also suffering great stock reductions due to habitat degradation caused by deforestation, landfills, sewage effluents, domestic and industrial wastes and the introduction of exotic fish in the Mucuri River estuary. The harvesting community was found to have significant ecological knowledge about the functioning of mangrove swamp ecology, the biology of crabs, and the mass mortality that directly affected the economy of this community, and this information was largely in accordance with scientific knowledge. Conclusions The study of traditional knowledge makes it possible to better understand human interactions with the environment and aids in the elaboration of appropriate strategies for natural

  11. Perceptions of environmental changes and lethargic crab disease among crab harvesters in a Brazilian coastal community.

    Science.gov (United States)

    Firmo, Angélica M S; Tognella, Mônica M P; Có, Walter L O; Barboza, Raynner R D; Alves, Rômulo R N

    2011-11-16

    Lethargic Crab Disease (LCD) has caused significant mortalities in the population of Ucides cordatus crabs in the Mucuri estuary in Bahia State, Brazil, and has brought social and economic problems to many crab-harvesting communities that depend on this natural resource. The present work examined the perceptions of members of a Brazilian crab harvesting community concerning environmental changes and the Lethargic Crab Disease. Field work was undertaken during the period between January and April/2009, with weekly or biweekly field excursions during which open and semi-structured interviews were held with local residents in the municipality of Mucuri, Bahia State, Brazil. A total of 23 individuals were interviewed, all of whom had at least 20 years of crab-collecting experience in the study region. Key-informants (more experienced crab harvesters) were selected among the interviewees using the "native specialist" criterion. According to the collectors, LCD reached the Mucuri mangroves between 2004 and 2005, decimating almost all crab population in the area, and in 2007, 2008 and 2009 high mortalities of U. cordatus were again observed as a result of recurrences of this disease in the region. In addition to LCD, crabs were also suffering great stock reductions due to habitat degradation caused by deforestation, landfills, sewage effluents, domestic and industrial wastes and the introduction of exotic fish in the Mucuri River estuary. The harvesting community was found to have significant ecological knowledge about the functioning of mangrove swamp ecology, the biology of crabs, and the mass mortality that directly affected the economy of this community, and this information was largely in accordance with scientific knowledge. The study of traditional knowledge makes it possible to better understand human interactions with the environment and aids in the elaboration of appropriate strategies for natural resource conservation.

  12. Burrow characteristics and habitat associations of armadillos in Brazil and the United States of America

    Directory of Open Access Journals (Sweden)

    Colleen M. McDonough

    2000-03-01

    Full Text Available We censused and measured armadillo burrows in ten 10 m x 40 m plots in each of four habitat types at a study site in northern Florida and one in the Atlantic coastal rainforest of Brazil. The nine-banded armadillo (Dasypus novemcinctus was the only species of armadillo found in Florida, but several additional species were present in Brazil. Burrows were more numerous but smaller in Brazil than in the U. S., probably due to the inclusion of burrows dug by the smaller congener D. septemcinctus. In Brazil, burrows were larger and more numerous in swamp and forest habitats than in grassland or disturbed areas, suggesting that D. novemcinctus is found primarily in forests and swamps while D. septemcinctus is located in the other areas. This was supported by data from sightings of live animals. In Florida, burrows were more numerous in hardwood hammocks than in wetlands, fields or upland pine areas, but burrow dimensions did not vary across habitat types. In Florida, armadillos were seen more frequently than expected in hammocks and wetlands and less frequently than expected in fields and upland pine areas. There were also age (juvenile versus adult, sex, and yearly differences in habitat use in Florida. Biomass, abundance, and species diversity of terrestrial invertebrates did not vary significantly between habitat types in Florida, suggesting that habitat associations of armadillos were not influenced by prey availability.

  13. Population models of burrowing mayfly recolonization in Western Lake Erie

    Science.gov (United States)

    Madenjian, C.P.; Schloesser, D.W.; Krieger, K.A.

    1998-01-01

    Burrowing mayflies, Hexagenia spp. (H. limbata and H. rigida), began recolonizing western Lake Erie during the 1990s. Survey data for mayfly nymph densities indicated that the population experienced exponential growth between 1991 and 1997. To predict the time to full recovery of the mayfly population, we fitted logistic models, ranging in carrying capacity from 600 to 2000 nymphs/m2, to these survey data. Based on the fitted logistic curves, we forecast that the mayfly population in western Lake Erie would achieve full recovery between years 1998 and 2000, depending on the carrying capacity of the western basin. Additionally, we estimated the mortality rate of nymphs in western Lake Erie during 1994 and then applied an age-based matrix model to the mayfly population. The results of the matrix population modeling corroborated the exponential growth model application in that both methods yielded an estimate of the population growth rate, r, in excess of 0.8 yr-1. This was the first evidence that mayfly populations are capable of recolonizing large aquatic ecosystems at rates comparable with those observed in much smaller lentic ecosystems. Our model predictions should prove valuable to managers of power plant facilities along the western basin in planning for mayfly emergences and to managers of the yellow perch (Perca flavescens) fishery in western Lake Erie.

  14. Antimicrobial lipids from the hemolymph of brachyuran crabs

    Digital Repository Service at National Institute of Oceanography (India)

    Ravichandran, S.; Wahidullah, S.; DeSouza, L.; Rameshkumar, G.

    The potential of marine crabs as a source of biologically active products is largely unexplored. In the present study, antimicrobial activity of the hemolymph (plasma) and hemocytes (plasma cells) of six brachyuran crabs was investigated against 16...

  15. Ghost crabs on a treadmill: Oxygen Uptake and Haemocyanin ...

    African Journals Online (AJOL)

    Ghost crabs Ocypode ceratophthalmus were exercised on a specially constructed treadmill. At a running speed of 13,3 cm s-1, most crabs ran for 2 h before getting fatigued. At this speed the oxygen consumption rate (MO2) was measured in time intervals for a total of 52 min. For exercised crabs the MO2 values are about ...

  16. 50 CFR 680.21 - Crab harvesting cooperatives.

    Science.gov (United States)

    2010-10-01

    ... establishes an annual catch limit of crab that is based on the collective QS holdings of the members of the... the members of the crab harvesting cooperative. (2) Contents of application for annual crab harvesting... permit may appeal the IAD using the appeals procedures described in § 680.43. (c) Restrictions on fishing...

  17. Genetic population structure of the Japanese mitten crab Eriocheir ...

    African Journals Online (AJOL)

    Fragment of 376 bp at the mitochondrial ND2 gene was sequenced for 133 individuals of Japanese mitten crab, Eriocheir japonica from 17 localities of Japan and 30 individuals of Chinese mitten crab, E. sinensis from 2 localities of China. In Japanese mitten crab, sequence comparison of this segment revealed 23 ...

  18. Burrow architecture, family composition and habitat characteristics of the largest social African mole-rat: the giant mole-rat constructs really giant burrow systems

    Czech Academy of Sciences Publication Activity Database

    Šumbera, R.; Mazoch, V.; Patzenhauerová, Hana; Lövy, M.; Šklíba, J.; Bryja, Josef; Burda, H.

    2012-01-01

    Roč. 57, č. 2 (2012), s. 121-130 ISSN 0001-7051 R&D Projects: GA AV ČR IAA601410802 Institutional research plan: CEZ:AV0Z60930519 Keywords : Fukomys mechowii * subterranean rodent * burrow system * kin structure * Bathyergidae Subject RIV: EG - Zoology Impact factor: 0.949, year: 2012

  19. The burrows of Parastacus defossus (Decapoda: Parastacidae, a fossorial freshwater crayfish from southern Brazil

    Directory of Open Access Journals (Sweden)

    Clarissa K. Noro

    2010-06-01

    Full Text Available Parastacus defossus Faxon, 1898 is a fossorial crayfish species, which constructs its burrows in swampy areas in southeast Uruguay and in the state of Rio Grande do Sul, Brazil. The present field study was carried out in Lami, Porto Alegre, Rio Grande do Sul, Brazil, from May 2003 through August 2005. Environmental measurements (temperature, pH, dissolved oxygen, and water-table depth of the water in the galleries were made monthly. Burrow morphology was analyzed by means of resin and gypsum casts. The spatial distribution and changes in the number and shape of the surface openings over time were observed in a 100 m² area. To estimate the spatial distribution of the openings, the observed distribution was compared with the expected distribution predicted by the Poisson and Negative Binomial frequency-distribution models. The adult population density was estimated by direct observation of burrows and counts in the study area. Inside the burrows of P. defossus, the water temperature ranged between 16.6°C (autumn 2004 and 23°C (spring 2003. The water was hypoxic and slightly acidic, and the dissolved oxygen content was very low (mean 1.43 mg/l (18.2% saturation. The soil with burrows had higher percentages of coarse sand, fine sand, and silt. The spatial distribution of the openings showed a significant fit to the Negative Binomial distribution, indicating that the distribution of the openings is aggregated, as confirmed from the burrow morphology. The galleries are always formed by a central tunnel with multiple branchings that connect the underground water to the soil surface by one or more openings, which can be recognized by the chimneys. From knowledge of the burrow morphology, the population density was estimated to be about 120 individuals/100 m².

  20. Impacts of crab bioturbation and local pollution on sulfate reduction, Hg distribution and methylation in mangrove sediments, Rio de Janeiro, Brazil.

    Science.gov (United States)

    Correia, Raquel Rose Silva; Guimarães, Jean Remy Davée

    2016-08-15

    Mercury (Hg) and methylmercury (MeHg) are highly toxic and poorly studied in mangroves. Burrowing Uca crabs change sediment topography and biogeochemistry and thus may affect Hg distribution and MeHg formation. We studied added (203)Hg distribution, Me(203)Hg formation and sulfate reduction rates (SRR) in sediment aquariums containing Uca leptodactyla; and analyzed profiles of Me(203)Hg formation and SRR in sediment cores from two mangroves with distinct environmental impacts. MeHg formation and SRR were higher in the top (≤6cm) sediment and there was no significant difference in Hg methylation in more or less impacted mangroves. In aquariums, crab bioturbation favored Hg retention in the sediment. In the treatment without crabs, Hg volatilization and water Hg concentrations were higher. Hg methylation was higher in bioturbated aquariums but SRR were similar in both treatments. These findings suggest that bioturbating activity favors Hg retention in sediment but also promotes MeHg formation near the surface. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Efficient Monitoring of CRAB Jobs at CMS

    Energy Technology Data Exchange (ETDEWEB)

    Silva, J. M.D. [Sao Paulo, IFT; Balcas, J. [Caltech; Belforte, S. [INFN, Trieste; Ciangottini, D. [INFN, Perugia; Mascheroni, M. [Fermilab; Rupeika, E. A. [Vilnius U.; Ivanov, T. T. [Sofiya U.; Hernandez, J. M. [Madrid, CIEMAT; Vaandering, E. [Fermilab

    2017-11-22

    CRAB is a tool used for distributed analysis of CMS data. Users can submit sets of jobs with similar requirements (tasks) with a single request. CRAB uses a client-server architecture, where a lightweight client, a server, and ancillary services work together and are maintained by CMS operators at CERN. As with most complex software, good monitoring tools are crucial for efficient use and longterm maintainability. This work gives an overview of the monitoring tools developed to ensure the CRAB server and infrastructure are functional, help operators debug user problems, and minimize overhead and operating cost. This work also illustrates the design choices and gives a report on our experience with the tools we developed and the external ones we used.

  2. Map-Based Repowering and Reorganization of a Wind Resource Area to Minimize Burrowing Owl and Other Bird Fatalities

    Directory of Open Access Journals (Sweden)

    Lee Neher

    2009-10-01

    Full Text Available Wind turbines in the Altamont Pass Wind Resource Area (Alameda/Contra Costa Counties, California, USA generate about 730 GWh of electricity annually, but have been killing thousands of birds each year, including >2,000 raptors and hundreds of burrowing owls. We have developed collision hazard maps and hazard ratings of wind turbines to guide relocation of existing wind turbines and careful repowering to modern turbines to reduce burrowing owl fatalities principally, and other birds secondarily. Burrowing owls selected burrow sites lower on slopes and on smaller, shallower slopes than represented by the average 10 × 10 m2 grid cell among 187,908 grid cells sampled from 2,281,169 grid cells comprising a digital elevation model (DEM of the study area. Fuzzy logic and discriminant function analysis produced likelihood surfaces encompassing most burrowing owl burrows within a fraction of the study area, and the former corresponded with burrowing owl fatalities and the latter with other raptor fatalities. Our ratings of wind turbine hazard were more predictive of burrowing owl fatalities, but would be more difficult to implement. Careful repowering to modern wind turbines would most reduce fatalities of burrowing owls and other birds while adding about 1,000 GWh annually toward California’s 33% Renewable Portfolio Standard.

  3. Map-based repowering and reorganization of a wind resource area to minimize burrowing owl and other bird fatalities

    Energy Technology Data Exchange (ETDEWEB)

    Smallwood, K. S. [Research Ecologist, 3108 Finch Street, Davis, CA 95616 (United States); Neher, L. [Gis Specialist, Neher Consulting, 7241 34th Street, North Highlands, CA 95660 (United States); Bell, D. A. [East Bay Regional Park District, 2950 Peralta Oaks Court, Oakland, CA 94605-0381 (United States)

    2009-07-01

    Wind turbines in the Altamont Pass Wind Resource Area (Alameda/Contra Costa Counties, California, USA) generate about 730 GWh of electricity annually, but have been killing thousands of birds each year, including >2,000 raptors and hundreds of burrowing owls. We have developed collision hazard maps and hazard ratings of wind turbines to guide relocation of existing wind turbines and careful repowering to modern turbines to reduce burrowing owl fatalities principally, and other birds secondarily. Burrowing owls selected burrow sites lower on slopes and on smaller, shallower slopes than represented by the average 10 x 10 m{sup 2} grid cell among 187,908 grid cells sampled from 2,281,169 grid cells comprising a digital elevation model (DEM) of the study area. Fuzzy logic and discriminant function analysis produced likelihood surfaces encompassing most burrowing owl burrows within a fraction of the study area, and the former corresponded with burrowing owl fatalities and the latter with other raptor fatalities. Our ratings of wind turbine hazard were more predictive of burrowing owl fatalities, but would be more difficult to implement. Careful repowering to modern wind turbines would most reduce fatalities of burrowing owls and other birds while adding about 1,000 GWh annually toward California's 33% Renewable Portfolio Standard. (author)

  4. Invasive Crabs in the Barents Sea

    DEFF Research Database (Denmark)

    Kaiser, Brooks; Fernandez, Linda; Kourantidou, Melina

    The recent invasions of the red king crab (RKC) and the snow crab (SC) in the Barents Sea represent the sorts of integrated ecological and economic shifts we may expect as climate change affects arctic seas. Economic incentives and ecological unknowns have combined to change the current...... and potentially future productivity and profitability of the Barents ecosystem in complex and interacting ways. We examine potential ecological-economic trajectories for these crabs’ continued expansions in the Arctic and how the profitability, the joint and national management structures in Norway and Russia...

  5. Arsenobetaine in the red crab, Chionoecetes opilio

    Energy Technology Data Exchange (ETDEWEB)

    Matsuto, S.; Stockton, R.A.; Irgolic, K.J.

    1986-01-01

    The meat of the red crab, Chionoecetes opilio, caught near the central coast the Japan Sea, was extracted with methanol. The arsenic compounds were isolated from this extract and purified by anion and cation exchange chromatography and thin-layer chromatography. Three arsenic compounds were detected. The major arsenic compound, identified as arsenobetaine by TLC, proton NMR spectroscopy, and high pressure liquid chromatography with an atomic absorption spectrometer as an arsenic-specific detector, accounted for 90% of the total arsenic in the crab meat. The other two arsenic compounds could not be identified because of insufficient amounts available for analysis.

  6. Observations on the use of tarantula burrows by the anurans Leptodactylus bufonius (Leptodactylidae and Rhinella major (Bufonidae in the Dry Chaco ecoregion of Bolivia

    Directory of Open Access Journals (Sweden)

    Christopher M. Schalk

    2014-06-01

    Full Text Available Some species of anurans have been observed utilizing burrows of other animals, such as rodents and tarantulas. Here we report the observations of two anuran species, Leptodactylus bufonius and Rhinella major, utilizing the burrows of tarantulas (Acanthoscurria sp.; Family Theraphosidae in the dry Chaco ecoregion of Bolivia. Both species of anurans never co-occurred with tarantulas in the burrows and used burrows that were wider in diameter and closer to breeding ponds as compared to the total available tarantula burrows in the area. These burrows may serve as refuges from predators, especially for conspicuous, calling males.

  7. Footprints in the sand: independent reduction of subdigital lamellae in the Namib–Kalahari burrowing geckos

    Science.gov (United States)

    Lamb, Trip; Bauer, Aaron M

    2005-01-01

    Many desert organisms exhibit convergence, and certain physical factors such as windblown sands have generated remarkably similar ecomorphs across divergent lineages. The burrowing geckos Colopus, Chondrodactylus and Palmatogecko occupy dune ecosystems in the Namib and Kalahari deserts of southwest Africa. Considered closely related, they share several putative synapomorphies, including reduced subdigital pads (toe pads) and spinose digital scales. Though recognized as part of Africa's ecologically diverse Pachydactylus Group, the burrowing geckos' precise phylogenetic affinities remain elusive. Convergent pedal modification provides a tenable alternative explaining the geckos' derived terrestriality and adaptation to Namib and Kalahari sands. We generated a molecular phylogeny for the Pachydactylus Group to examine evolutionary relationships among the burrowing geckos and infer historical patterns of pedal character change. Bayesian and parsimony analyses revealed all three burrowing genera to be deeply nested within Pachydactylus, each genus belonging to a separate clade. Strong support for these distinct clades indicates ecomorphological adaptations for burrowing have evolved independently three times in the southern Pachydactylus Group. We argue that the physical properties of Namib and Kalahari sands played a principal role in selecting for pedal similarity. PMID:16618680

  8. Footprints in the sand: independent reduction of subdigital lamellae in the Namib-Kalahari burrowing geckos.

    Science.gov (United States)

    Lamb, Trip; Bauer, Aaron M

    2006-04-07

    Many desert organisms exhibit convergence, and certain physical factors such as windblown sands have generated remarkably similar ecomorphs across divergent lineages. The burrowing geckos Colopus, Chondrodactylus and Palmatogecko occupy dune ecosystems in the Namib and Kalahari deserts of southwest Africa. Considered closely related, they share several putative synapomorphies, including reduced subdigital pads (toe pads) and spinose digital scales. Though recognized as part of Africa's ecologically diverse Pachydactylus Group, the burrowing geckos' precise phylogenetic affinities remain elusive. Convergent pedal modification provides a tenable alternative explaining the geckos' derived terrestriality and adaptation to Namib and Kalahari sands. We generated a molecular phylogeny for the Pachydactylus Group to examine evolutionary relationships among the burrowing geckos and infer historical patterns of pedal character change. Bayesian and parsimony analyses revealed all three burrowing genera to be deeply nested within Pachydactylus, each genus belonging to a separate clade. Strong support for these distinct clades indicates ecomorphological adaptations for burrowing have evolved independently three times in the southern Pachydactylus Group. We argue that the physical properties of Namib and Kalahari sands played a principal role in selecting for pedal similarity.

  9. Dusk but not dawn burrow emergence rhythms of Nephrops norvegicus (Crustacea: Decapoda

    Directory of Open Access Journals (Sweden)

    Valerio Sbragaglia

    2013-10-01

    Full Text Available The Norway lobster, Nephrops norvegicus, can be captured by haul nets only during the emergence from its burrow. In the last few decades, an extensive field research revealed distinct diel (24-h–based catchability patterns at different depths. Laboratory experiments suggested that burrow emergence (used as a proxy of catchability is endogenously controlled via a circadian system. Results were usually presented in terms of mean effects without a quantification of inter-individual variability and arrhythmia. Here, we studied the burrow emergence of 52 adult Nephrops by an infrared actograph endowed with an artificial burrow. Animals were exposed to 12-12 h light-darkness cycle, simulating photic condition of the lower shelf. Forty-five animals showed rhythmic emergence (87%, while seven were arrhythmic (13%. Rhythmic animals were clustered according to their timing of emergence: 54% at dusk and 4% at dawn. Moreover, other animals showed fully diurnal or nocturnal emergence (10% and 19%, respectively. The comparison of our results with those derived from temporally scheduled trawling indicates that bimodal catch patterns observed in shelf populations are poorly observed during individual experiments in the laboratory, where the same light conditions are simulated. Nephrops burrow emergence seems to be the result of a mixed endogenous-exogenous control, while arrhythmia could also be present in the wild.

  10. Burrow ventilation and associated porewater irrigation by the polychaete Marenzelleria viridis

    DEFF Research Database (Denmark)

    Quintana, Cintia Organo; Hansen, Torben; Delefosse, Matthieu

    2011-01-01

    presented muscular pumping in time averaged rates of 0.15 ml min−1. Oxygen needle electrodes positioned above the burrow openings revealed that muscular undulation of the worm body pumps anoxic water out of the burrow. On the other hand, microscope observations of the animal showed that ventilation...... be about 0.16 ml min−1. Since the cilia pumping into the burrow occurs in periods of 24±12 min and at 50–70% of the measured time, considerable amounts of water from deeper sediments may percolate upwards to the sediment surface. This water is rich in reduced compounds and nutrients and may have important...

  11. Influence of vegetation on the nocturnal foraging behaviors and vertebrate prey capture by endangered Burrowing Owls

    Directory of Open Access Journals (Sweden)

    Alan Marsh

    2014-06-01

    Full Text Available Restrictions in technology have limited past habitat selection studies for many species to the home-range level, as a finer-scale understanding was often not possible. Consequently, these studies may not identify the true mechanism driving habitat selection patterns, which may influence how such results are applied in conservation. We used GPS dataloggers with digital video recorders to identify foraging modes and locations in which endangered Burrowing Owls (Athene cunicularia captured prey. We measured the coarse and fine-scale characteristics of vegetation at locations in which owls searched for, versus where they caught, vertebrate prey. Most prey items were caught using hover-hunting. Burrowing Owls searched for, and caught, vertebrate prey in all cover types, but were more likely to kill prey in areas with sparse and less dense vegetative cover. Management strategies designed to increase Burrowing Owl foraging success in the Canadian prairies should try to ensure a mosaic of vegetation heights across cover types.

  12. Habitat requirements and burrowing depths of rodents in relation to shallow waste burial sites

    Energy Technology Data Exchange (ETDEWEB)

    Gano, K.A.; States, J.B.

    1982-05-01

    The purpose of this paper is to provide a review of the literature and summarize information on factors affecting habitat selection and maximum recorded burrowing depths for representative small mammals that we consider most likely to inhibit waste burial sites in arid and semi-arid regions of the West. The information is intended for waste management designers who need to know what to expect from small mammals that may be present at a particular site. Waste repositories oculd be designed to exclude the deep burrowing rodents of a region by creating an unattractive habitat over the waste. Summaries are given for habitat requirements of each group along with generalized modifications that could be employed to deter habitation. Representatives from the major groups considered to be deep burrowers are discussed. Further, detailed information about a particular species can be obtained from the references cited.

  13. Habitat requirements and burrowing depths of rodents in relation to shallow waste burial sites

    International Nuclear Information System (INIS)

    Gano, K.A.; States, J.B.

    1982-05-01

    The purpose of this paper is to provide a review of the literature and summarize information on factors affecting habitat selection and maximum recorded burrowing depths for representative small mammals that we consider most likely to inhibit waste burial sites in arid and semi-arid regions of the West. The information is intended for waste management designers who need to know what to expect from small mammals that may be present at a particular site. Waste repositories oculd be designed to exclude the deep burrowing rodents of a region by creating an unattractive habitat over the waste. Summaries are given for habitat requirements of each group along with generalized modifications that could be employed to deter habitation. Representatives from the major groups considered to be deep burrowers are discussed. Further, detailed information about a particular species can be obtained from the references cited

  14. Breeding-season food habits of burrowing owls (Athene cunicularia) in southwestern Dominican Republic

    Science.gov (United States)

    Wiley, J.W.

    1998-01-01

    Diet data from 20 Burrowing Owl (Athene cunicularia) nests were collected in southwestern Dominican Republic in 1976, 1982, and 1996. Invertebrates (53.3%) comprised the most numerous prey items (N = 396) delivered to nests by adult owls, but vertebrates (46.7%) were much better represented than in other studies of Burrowing Owl diet. Among vertebrates, birds (28.3% of all items) and reptiles (14.9%) were most important, whereas mammals (1.0%) and amphibians (2.5%) were less commonly delivered to nests. Vertebrates, however, comprised more than twice (69.2%) of the total biomass as invertebrates (30.8%), with birds (50.4%) and reptiles (12.8%) the most important of the vertebrate prey classes. A positive relationship was observed between bird species abundance and number of individuals taken as prey by Burrowing Owls.

  15. Ocean acidification impairs crab foraging behaviour.

    Science.gov (United States)

    Dodd, Luke F; Grabowski, Jonathan H; Piehler, Michael F; Westfield, Isaac; Ries, Justin B

    2015-07-07

    Anthropogenic elevation of atmospheric CO2 is driving global-scale ocean acidification, which consequently influences calcification rates of many marine invertebrates and potentially alters their susceptibility to predation. Ocean acidification may also impair an organism's ability to process environmental and biological cues. These counteracting impacts make it challenging to predict how acidification will alter species interactions and community structure. To examine effects of acidification on consumptive and behavioural interactions between mud crabs (Panopeus herbstii) and oysters (Crassostrea virginica), oysters were reared with and without caged crabs for 71 days at three pCO2 levels. During subsequent predation trials, acidification reduced prey consumption, handling time and duration of unsuccessful predation attempt. These negative effects of ocean acidification on crab foraging behaviour more than offset any benefit to crabs resulting from a reduction in the net rate of oyster calcification. These findings reveal that efforts to evaluate how acidification will alter marine food webs should include quantifying impacts on both calcification rates and animal behaviour. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  16. Corneal laceration caused by river crab

    Directory of Open Access Journals (Sweden)

    Vinuthinee N

    2015-01-01

    Full Text Available Naidu Vinuthinee,1,2 Anuar Azreen-Redzal,1 Jaafar Juanarita,1 Embong Zunaina2 1Department of Ophthalmology, Hospital Sultanah Bahiyah, Alor Setar, 2Department of Ophthalmology, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, Malaysia Abstract: A 5-year-old boy presented with right eye pain associated with tearing and photophobia of 1-day duration. He gave a history of playing with a river crab when suddenly the crab clamped his fingers. He attempted to fling the crab off, but the crab flew and hit his right eye. Ocular examination revealed a right eye corneal ulcer with clumps of fibrin located beneath the corneal ulcer and 1.6 mm level of hypopyon. At presentation, the Seidel test was negative, with a deep anterior chamber. Culture from the corneal scrapping specimen grew Citrobacter diversus and Proteus vulgaris, and the boy was treated with topical gentamicin and ceftazidime eyedrops. Fibrin clumps beneath the corneal ulcer subsequently dislodged, and revealed a full-thickness corneal laceration wound with a positive Seidel test and shallow anterior chamber. The patient underwent emergency corneal toileting and suturing. Postoperatively, he was treated with oral ciprofloxacin 250 mg 12-hourly for 1 week, topical gentamicin, ceftazidime, and dexamethasone eyedrops for 4 weeks. Right eye vision improved to 6/9 and 6/6 with pinhole at the 2-week follow-up following corneal suture removal. Keywords: corneal ulcer, pediatric trauma, ocular injury

  17. Belted kingfishers: Under surveillance and sampled in the privacy of their own burrow

    International Nuclear Information System (INIS)

    Baron, L.A.; Ashwood, T.L.

    1995-01-01

    The belted kingfisher, a common piscivore of the Oak Ridge Reservation (ORR), bioaccumulates contaminants from consumption of aquatic prey. Three kingfisher carcasses found near contaminated streams on the ORR were analyzed. Mercury, cadmium, and selenium bioaccumulated within the liver, kidney, and feathers. Additionally, PCB-1254 accumulated in muscle and lipid tissue, while Cesium-137 accumulated within the muscle and whole body. These contaminant levels have been shown to produce a variety of toxicological effects (i.e., reproductive impairment, central nervous system dysfunction) within other species of birds. In addition to use of this data for ecological risk assessment, kingfishers can also be monitored as a viable bioindicator species reflecting environmental contaminant levels over time. However, current sampling methods of burrow excavation or the use of mist nets can be detrimental to the reproductive success of the birds. The authors present a method for obtaining adequate samples of feathers and other remnants (i.e., egg shells, dried regurgitant) found in the burrow during or following the nesting season. The collection of samples following surveillance of the burrow and its contents was performed with the use of a 15 ft-long flexible, portable probe containing a video camera. Once sighted with the probe, contents of the burrow were collected by insertion of an additional tube attached to a hand held vacuum cleaner (Dirt Devil reg-sign). Feathers collected from a nest at an uncontaminated site contained selenium, lead and mercury. Cesium-137 was found in an egg shell collected from a nest at a radiologically contaminated site. Close-up photos of a kingfisher mother incubating her eggs and nestlings within two burrows will also be shown. This surveillance and sampling technique can also be used for monitoring other burrowing terrestrial species

  18. Pisodonophis boro (ophichthidae: anguilliformes): specialization for head-first and tail-first burrowing?

    Science.gov (United States)

    De Schepper, Natalie; De Kegel, Barbara; Adriaens, Dominique

    2007-02-01

    The rice paddy eel, Pisodonophis boro (P. boro), is of special interest because of its peculiar burrowing habits. P. boro penetrates the substrate tail-first, a technique common for ophichthids, but it is able to burrow head-first as well. P. boro exhibits three feeding modes: inertial feeding, grasping, and spinning. Rotational feeding is a highly specialized feeding mode, adopted by several elongate, aquatic vertebrates and it is likely that some morphological modifications are related to this feeding mode. The detailed morphology of the head and tail of P. boro is examined with the goal to apportion the anatomical specializations among head-first burrowing, tail-first burrowing, and rotational feeding. The reduced eyes, covered with thick corneas may be beneficial for protection during head-first burrowing, but at the same time decreased visual acuity may have an impact on other sensory systems (e.g. cephalic lateral line system). The elongated and pointed shape of the skull is beneficial for substrate penetration. The cranial bones and their joints, which are fortified, are advantageous for resisting high mechanical loads during head-first burrowing. The aponeurotic connection between epaxial and jaw muscles is considered beneficial for transferring these forces from the body to the head during rotational feeding. Hypertrophied jaw muscles facilitate a powerful bite, which is required to hold prey during spinning movements and variability in the fiber angles of subdivisions of jaw muscles may be beneficial for preventing the lower jaw from being dislodged or opened. Furthermore, firm upper (premaxillo-ethmovomerine complex) and lower jaws (with robust coronoid processes) and high neurocranial rigidity are advantageous for a solid grip to hold prey during rotational feeding. The pointed shape of the tail and the consolidated caudal skeleton are beneficial for their tail-first burrowing habits. It is quite likely that the reduction of the caudal musculature is

  19. Variations in the Foraging Behaviour and Burrow Structures of the Damara Molerat Cryptomys damarensis in the Kalahari Gemsbok National Park

    Directory of Open Access Journals (Sweden)

    B.G. Lovegrove

    1987-10-01

    Full Text Available Aspects of two habitat-specific foraging behaviours of the social subterranean rodent Cryptomys damarensis, are discussed in terms of burrow structure, resource dispersion patterns, sand moisture content, burrow temperature regimes, and predatory pressures, in the Kalahari Gemsbok National Park, South Africa.

  20. Non-Native Suckermouth Armored Catfishes in Florida: Description of Nest Borrows and Burrow Colonies with Assessment of Shoreline Conditions

    Science.gov (United States)

    2009-04-01

    clubhouses and other residences with boat docks, and a mix of other land uses. Most waterway reaches surveyed were located in rural or low-density...were excavated to obtain in- formation on burrow dimensions. In contrast to what Grier (1980) had described for Hypostomus burrows in Florida, Devick

  1. Detecting plague-host abundance from space: Using a spectral vegetation index to identify occupancy of great gerbil burrows

    NARCIS (Netherlands)

    Wilschut, Liesbeth I.; Heesterbeek, Johan A.P.; Begon, Mike; de Jong, Steven M.; Ageyev, Vladimir; Laudisoit, Anne; Addink, Elisabeth A.

    2018-01-01

    In Kazakhstan, plague outbreaks occur when its main host, the great gerbil, exceeds an abundance threshold. These live in family groups in burrows, which can be mapped using remote sensing. Occupancy (percentage of burrows occupied) is a good proxy for abundance and hence the possibility of an

  2. Detecting plague-host abundance from space: Using a spectral vegetation index to identify occupancy of great gerbil burrows

    Science.gov (United States)

    Wilschut, Liesbeth I.; Heesterbeek, Johan A. P.; Begon, Mike; de Jong, Steven M.; Ageyev, Vladimir; Laudisoit, Anne; Addink, Elisabeth A.

    2018-02-01

    In Kazakhstan, plague outbreaks occur when its main host, the great gerbil, exceeds an abundance threshold. These live in family groups in burrows, which can be mapped using remote sensing. Occupancy (percentage of burrows occupied) is a good proxy for abundance and hence the possibility of an outbreak. Here we use time series of satellite images to estimate occupancy remotely. In April and September 2013, 872 burrows were identified in the field as either occupied or empty. For satellite images acquired between April and August, 'burrow objects' were identified and matched to the field burrows. The burrow objects were represented by 25 different polygon types, then classified (using a majority vote from 10 Random Forests) as occupied or empty, using Normalized Difference Vegetation Indices (NDVI) calculated for all images. Throughout the season NDVI values were higher for empty than for occupied burrows. Occupancy status of individual burrows that were continuously occupied or empty, was classified with producer's and user's accuracy values of 63 and 64% for the optimum polygon. Occupancy level was predicted very well and differed 2% from the observed occupancy. This establishes firmly the principle that occupancy can be estimated using satellite images with the potential to predict plague outbreaks over extensive areas with much greater ease and accuracy than previously.

  3. Current status, distribution, and conservation of the Burrowing Owl (Speotyto cunicularia) in midwestern and western North America

    Science.gov (United States)

    Steven R. Sheffield

    1997-01-01

    The Burrowing Owl (Speotyto cunicularia) inhabits open prairie grassland habitat in the midwestern and western US and Canada. For several years now, numbers of this species in North America have been declining at an alarming rate. Currently, Burrowing Owls are listed as endangered in Canada and threatened in Mexico. In the United States, the...

  4. Nelson's big horn sheep (Ovis canadensis nelsoni) trample Agassiz's desert tortoise (Gopherus agassizii) burrow at a California wind energy facility

    Science.gov (United States)

    Agha, Mickey; Delaney, David F.; Lovich, Jeffrey E.; Briggs, Jessica; Austin, Meaghan; Price, Steven J.

    2015-01-01

    Research on interactions between Agassiz's desert tortoises (Gopherus agassizii) and ungulates has focused exclusively on the effects of livestock grazing on tortoises and their habitat (Oldemeyer, 1994). For example, during a 1980 study in San Bernardino County, California, 164 desert tortoise burrows were assessed for vulnerability to trampling by domestic sheep (Ovis aries). Herds of grazing sheep damaged 10% and destroyed 4% of the burrows (Nicholson and Humphreys 1981). In addition, a juvenile desert tortoise was trapped and an adult male was blocked from entering a burrow due to trampling by domestic sheep. Another study found that domestic cattle (Bos taurus) trampled active desert tortoise burrows and vegetation surrounding burrows (Avery and Neibergs 1997). Trampling also has negative impacts on diversity of vegetation and intershrub soil crusts in the desert southwest (Webb and Stielstra 1979). Trampling of important food plants and overgrazing has the potential to create competition between desert tortoises and domestic livestock (Berry 1978; Coombs 1979; Webb and Stielstra 1979).

  5. Grooming behaviors and gill fouling in the commercially important blue crab (Callinectes sapidus and stone crab (Menippe mercenaria

    Directory of Open Access Journals (Sweden)

    Jen L. Wortham

    2017-10-01

    Full Text Available Abstract Grooming behaviors reduce fouling of body regions. In decapods, grooming time budgets, body regions groomed, and grooming appendages are known in several species; however, little data exists on brachyuran crabs. In this study, grooming behaviors of two commercially important crabs were documented (blue crabs: Callinectes sapidus Rathbun, 1896; stone crabs: Menippe mercenaria Say, 1818. These crabs are harvested by fishermen and knowing their grooming behaviors is valuable, as clean crabs are preferred by consumers and the stone crab fishery consequence of removing one cheliped to grooming behaviors is unknown. Crabs were observed individually and agonistically to determine how grooming behaviors vary in the presence of another conspecific. Both species frequently use their maxillipeds and groom, with the gills being cleaned by epipods. Respiratory and sensory structures were groomed frequently in both species. Removal of a grooming appendage resulted in higher fouling levels in the gills, indicating that grooming behaviors do remove fouling. Overall, stone crabs had a larger individual time budget for grooming, but agonistic grooming time budgets were similar. Stone crab chelipeds are used in grooming, especially cleaning the other cheliped. The chelipeds are not the main grooming appendage; however, implications of losing one cheliped may have large impacts.

  6. Ecomorphology of crabs and swimming crabs (Crustacea DecapodaBrachyura from coastal ecosystems

    Directory of Open Access Journals (Sweden)

    Murilo Zanetti Marochi

    Full Text Available Abstract Brachyuran crabs are one of the most diverse taxa of crustaceans, occurring in almost all coastal habitats. Due to their high morphological diversification, the authors sought to ascertain the existence of morphological patterns related to the habitat of coastal brachyuran crabs. We analyzed 17 species from mangrove forests, rocky shores, sandy beaches and exclusively aquatic marine/estuarine ecosystems. A total of 16 linear measurements of males and 17 of females were obtained for each habitat. We were able to discriminate three functional groups of crab species, based on their habitat: 1. Complex Substrates, 2. Semiterrestrial, 3. Exclusively Aquatic. The species belonging to the Complex Substrates group had long ambulatory legs, as well as being heteroquely related to uneven terrain. Semiterrestrial species showed ambulatory legs of different sizes, allowing them to walk easily on the terrestrial terrain due to the long fourth ambulatory leg, and long eyestalks which are important for visual communication. Exclusively Aquatic species showed the largest carapace widths and the shortest eyestalks. The presence of different crab lineages in the environments analyzed allows us to demonstrate the clear evolutionary convergence, by which the crabs adapted to their specific habitat and environment.

  7. Predatory blue crabs induce stronger nonconsumptive effects in eastern oysters Crassostrea virginica than scavenging blue crabs

    Directory of Open Access Journals (Sweden)

    Avery E. Scherer

    2017-02-01

    Full Text Available By influencing critical prey traits such as foraging or habitat selection, predators can affect entire ecosystems, but the nature of cues that trigger prey reactions to predators are not well understood. Predators may scavenge to supplement their energetic needs and scavenging frequency may vary among individuals within a species due to preferences and prey availability. Yet prey reactions to consumers that are primarily scavengers versus those that are active foragers have not been investigated, even though variation in prey reactions to scavengers or predators might influence cascading nonconsumptive effects in food webs. Oysters Crassostrea virginica react to crab predators by growing stronger shells. We exposed oysters to exudates from crabs fed live oysters or fed aged oyster tissue to simulate scavenging, and to controls without crab cues. Oysters grew stronger shells when exposed to either crab exudate, but their shells were significantly stronger when crabs were fed live oysters. The stronger response to predators than scavengers could be due to inherent differences in diet cues representative of reduced risk in the presence of scavengers or to degradation of conspecific alarm cues in aged treatments, which may mask risk from potential predators subsisting by scavenging.

  8. Status of LHC crab activity simulations and beam studies

    International Nuclear Information System (INIS)

    Calaga, R.; Assman, R.; Barranco, J.; Barranco, J.; Calaga, R.; Caspers, F.; Ciapala, E.; De-Maria, R.; Koutchouk, J. P.; Linnecar, T.; Metral, E.; Morita, A.; Solyak, N.; Sun, Y.; Tomas, R.; Tuckmantel, J.; Weiler, T.; Zimmermann, F.

    2009-01-01

    The LHC crab cavity program is advancing rapidly towards a first prototype which is anticipated to be tested during the early stages of the LHC phase I upgrade and commissioning. The general project status and some aspects related to crab optics, collimation, aperture constraints, impedances, noise effects. beam transparency and machine protection critical for a safe and robust operation of LHC beams with crab cavities are addressed here

  9. Crab Cavities: Past, Present, and Future of a Challenging Device

    OpenAIRE

    Wu, Q

    2015-01-01

    In two-ring facilities operating with a crossing-angle collision scheme, luminosity can be limited due to an incomplete overlapping of the colliding bunches. Crab cavities then are introduced to restore head-on collisions by providing the destined opposite deflection to the head and tail of the bunch. An increase in luminosity was demonstrated at KEKB with global crab- crossing, while the Large Hardron Collider (LHC) at CERN currently is designing local crab crossing for the Hi-Lumi upgrade. ...

  10. Lizard burrows provide thermal refugia for larks in the Arabian desert

    NARCIS (Netherlands)

    Williams, JB; Tieleman, BI; Shobrak, M

    A common perception is that desert birds experience greater extremes of heat and aridity than their mammalian counterparts, in part, because birds do not use burrows as a refuge from the desert environment. We report observations of Dunn's Larks (Eremalauda dunni), Bar-tailed Desert Larks (Ammomanes

  11. Strong population genetic structure and larval dispersal capability of the burrowing ghost shrimp (Neotrypaea californiensis)

    Science.gov (United States)

    The burrowing ghost shrimp, Neotrypaea californiensis, is a vital member of the estuarine benthic community. Dense populations of shrimp are found in the major estuaries of Washington and Oregon. Our study determines the genetic structure of shrimp populations in order to gain ...

  12. Burrowing Behavior of a Deposit Feeding Bivalve Predicts Change in Intertidal Ecosystem State

    NARCIS (Netherlands)

    Compton, T.J.; Bodnar, W.; Koolhaas, A.; Dekinga, A.; Holthuijsen, S.; Ten Horn, J.; McSweeney, N.; van Gils, J.A.; Piersma, T.

    2016-01-01

    Behavior has a predictive power that is often underutilized as a tool for signaling ecological change. The burrowing behavior of the deposit feeding bivalve Macoma balthica reflects a typical food-safety trade-off. The choice to live close to the sediment surface comes at a risk of predation and is

  13. Burrowing behavior of a deposit feeding bivalve predicts change in intertidal ecosystem state

    NARCIS (Netherlands)

    Compton, Tanya J.; Bodnar, Wanda; Koolhaas, Anita; Dekinga, Anne; Holthuijsen, Sander; ten Horn, Job; McSweeney, Niamh; van Gils, Jan; Piersma, Theunis

    2016-01-01

    Behavior has a predictive power that is often underutilized as a tool for signaling ecological change. The burrowing behavior of the deposit feeding bivalve Macoma balthica reflects a typical food-safety trade-off. The choice to live close to the sediment surface comes at a risk of predation and is

  14. The influence of small-mammal burrowing activity on water storage at the Hanford Site

    International Nuclear Information System (INIS)

    Landeen, D.S.

    1994-01-01

    This paper summarizes the activities that were conducted in support of the long-term surface barrier development program by Westinghouse Hanford Company to determine the degree that small-mammal burrow systems affect the loss or retention of water in the soils at the Hanford Site in Washington state. An animal intrusion lysimeter facility was constructed, consisting of two outer boxes buried at grade, which served as receptacles for six animal intrusion lysimeters. Small burrowing animals common the Hanford Site were introduced over a 3- to 4-month period. Supplemental precipitation was added monthly to three of the lysimeters with a rainfall simulator (rainulator). Information collected from the five tests indicated that (1) during summer months, water was lost in all the lysimeters, including the supplemental precipitation added with the rainulator; and (2) during winter months, all lysimeters gained water. The data indicate little difference in the amount of water stored between control and animal lysimeters. The overall water loss was attributed to surface evaporation, a process that occurred equally in control and treatment lysimeters. Other causes of water loss are a result of (1) constant soil turnover and subsequent drying, and (2) burrow ventilation effects. This suggests that burrow systems will not contribute to any significant water storage at depth and, in fact, may enhance the removal of water from the soil

  15. Burrowing herbivores alter soil carbon and nitrogen dynamics in a semi-arid ecosystem, Argentina

    Science.gov (United States)

    Kenneth L. Clark; Lyn C. Branch; Jose L. Hierro; Diego Villarreal

    2016-01-01

    Activities of burrowing herbivores, including movement of soil and litter and deposition of waste material, can alter the distribution of labile carbon (C) and nitrogen (N) in soil, affecting spatial patterning of nutrient dynamics in ecosystems where they are abundant. Their role in ecosystem processes in surface soil has been studied extensively, but effects of...

  16. Burrowing and avoidance behaviour in marine organisms exposed to pesticide-contaminated sediment

    DEFF Research Database (Denmark)

    Møhlenberg, Flemming; Kiørboe, Thomas

    1983-01-01

    Behavioural effects of marine sediment contaminated with pesticides (6000 ppm parathion, 200 ppm methyl parathion, 200 ppm malathion) were studied in a number of marine organisms in laboratory tests and in situ. The burrowing behaviour in Macoma baltica, Cerastoderma edule, Abra alba, Nereis...

  17. Living in a ``stethoscope'': burrow-acoustics promote auditory specializations in subterranean rodents

    Science.gov (United States)

    Lange, Simone; Burda, Hynek; Wegner, Regina E.; Dammann, Philip; Begall, Sabine; Kawalika, Mathias

    2007-02-01

    Subterranean mammals rely to a great extent on audition for communication and to be alerted to danger. The only hitherto published report on burrow acoustics revealed that in tunnels of blind mole-rats ( Spalax ehrenbergi), airborne sounds of 440 Hz propagated best whereas lower and higher frequencies were effectively attenuated. Morpho-functional analyses classify the ear of subterranean mammals as a low-sensitivity and low-frequency device. Concordantly, hearing is characterized by low sensitivity and a restricted frequency range tuned to low frequencies (0.5-4 kHz). Some authors considered the restricted hearing in subterranean mammals vestigial and degenerate due to under-stimulation. In contrast to this view stand a rich (mostly low-frequency) vocal repertoire and progressive structural specializations of the middle and inner ear. Thus, other authors considered these hearing characteristics adaptive. To test the hypothesis that acoustical environment in burrows of different species of subterranean mammals is similar, we measured sound attenuation in burrows of Fukomys mole-rats (formerly known as Cryptomys, cf. Kock et al. 2006) of two differently sized species at different locations in Zambia. We show that in these burrows, low-frequency sounds (200-800 Hz) are not only least attenuated but also their amplitude may be amplified like in a stethoscope (up to two times over 1 m). We suggest that hearing sensitivity has decreased during evolution of subterranean mammals to avoid over-stimulation of the ear in their natural environment.

  18. Organic matter composition and the protist and nematode communities around anecic earthworm burrows

    NARCIS (Netherlands)

    Andriuzzi, Walter S.; Ngo, Phuong-Thi; Geisen, Stefan; Keith, Aidan M.; Dumack, Kenneth; Bolger, Thomas; Bonkowski, Michael; Brussaard, Lijbert; Faber, Jack H.; Chabbi, Abad; Rumpel, Cornelia; Schmidt, Olaf

    2016-01-01

    By living in permanent burrows and incorporating organic detritus from the soil surface, anecic earthworms contribute to soil heterogeneity, but their impact is still under-studied in natural field conditions. We investigated the effects of the anecic earthworm Lumbricus centralis on fresh carbon

  19. Development of earthworm burrow systems and the influence of earthworms on soil hydrology

    NARCIS (Netherlands)

    Ligthart, T.N.

    1996-01-01


    Inoculation of earthworms can help to restore or ameliorate land qualities. Earthworms create burrows and alter the structure of the soil matrix, which influence the water infiltration, drainage, water retention and the aeration of the soil. The way and rate of the development of

  20. Sedimentary organic matter distributions, burrowing activity, and biogeochemical cycling: Natural patterns and experimental artifacts

    Science.gov (United States)

    Michaud, Emma; Aller, Robert, C.; Stora, Georges

    2010-11-01

    The coupling between biogenic reworking activity and reactive organic matter patterns within deposits is poorly understood and often ignored. In this study, we examined how common experimental treatments of sediment affect the burrowing behavior of the polychaete Nephtys incisa and how these effects may interact with reactive organic matter distributions to alter diagenetic transport - reaction balances. Sediment and animals were recovered from a subtidal site in central Long Island Sound, USA. The upper 15 cm of the sediment was sectioned into sub-intervals, and each interval separately sieved and homogenized. Three initial distributions of sediment and organic substrate reactivity were setup in a series of microcosms: (1) a reconstituted natural pattern with surface-derived sediment overlying sediment obtained from progressively deeper material to a depth of 15 cm (Natural); (2) a 15 cm thick sediment layer composed only of surface-derived sediment (Rich); and (3) a 15 cm thick layer composed of uniformally mixed sediment from the original 15 cm sediment profile (Averaged). The two last treatments are comparable to that used in microcosms in many previous studies of bioturbation and interspecific functional interaction experiments. Sediment grain size distributions were 97.5% silt-clay and showed no depth dependent patterns. Sediment porosity gradients were slightly altered by the treatments. Nepthys were reintroduced and aquariums were X-rayed regularly over 5 months to visualize and quantify spatial and temporal dynamics of burrows. The burrowing behaviour of adult populations having similar total biovolume, biomass, abundance, and individual sizes differed substantially as a function of treatment. Burrows in sediment with natural property gradients were much shallower and less dense than those in microcosms with altered gradients. The burrow volume/biovolume ratio was also lower in the substrate with natural organic reactivity gradients. Variation in food

  1. Lattice Upgrade Plan for Crab Crossing at the KEKB Rings

    CERN Document Server

    Morita, Akio; Hosoyama, K; Koiso, Haruyo; Kubo, T; Masuzawa, Mika; Ohmi, Kazuhito; Oide, Katsunobu; Sugahara, Ryuhei; Yoshida, Masato

    2005-01-01

    We plan to install two superconducting crab cavities into the rings at Janyary, 2006. In our plan, we will install one crab cavity per one ring into the NIKKO straight section where the cryogenic infrastructure is already operated for the superconducting accelerating cavities. In order to obtain the correct crabbing angle at the interaction point(IP), we have to enlarge the horizontal beta function(200m for HER) and have to adjust the horizontal phase advance between the IP and the cavity installation point. In this paper, we will report the lattice modified for the crab crossing and the study results about the single beam dynamics.

  2. FACT. Energy spectrum of the Crab Nebula

    Energy Technology Data Exchange (ETDEWEB)

    Temme, Fabian; Einecke, Sabrina; Buss, Jens [TU Dortmund, Experimental Physics 5, Otto-Hahn-Str.4, 44221 Dortmund (Germany); Collaboration: FACT-Collaboration

    2016-07-01

    The First G-APD Cherenkov Telescope is the first Imaging Air Cherenkov Telescope which uses silicon photon detectors (G-APDs aka SiPM) as photo sensors. With more than four years of operation, FACT proved an application of SiPMs is suitable for the field of ground-based gamma-ray astronomy. Due to the stable flux at TeV energies, the Crab Nebula is handled as a ''standard candle'' in Cherenkov astronomy. The analysis of its energy spectrum and comparison with other experiments, allows to evaluate the performance of FACT. A modern analysis chain, based on data stream handling and multivariate analysis methods was developed in close cooperation with the department of computer science at the TU Dortmund. In this talk, this analysis chain and its application are presented. Further to this, results, including the energy spectrum of the Crab Nebula, measured with FACT, are shown.

  3. Burrowing with a kinetic snout in a snake (Elapidae: Aspidelaps scutatus).

    Science.gov (United States)

    Deufel, Alexandra

    2017-12-01

    Of the few elongate, fossorial vertebrates that have been examined for their burrowing mechanics, all were found to use an akinetic, reinforced skull to push into the soil, powered mostly by trunk muscles. Reinforced skulls were considered essential for head-first burrowing. In contrast, I found that the skull of the fossorial shield-nosed cobra (Aspidelaps scutatus) is not reinforced and retains the kinetic potential typical of many non-fossorial snakes. Aspidelaps scutatus burrows using a greatly enlarged rostral scale that is attached to a kinetic snout that is independently mobile with respect to the rest of the skull. Two mechanisms of burrowing are used: (1) anteriorly directed head thrusts from a loosely bent body that is anchored against the walls of the tunnel by friction, and (2) side-to-side shovelling using the head and rostral scale. The premaxilla, to which the rostral scale is attached, lacks any direct muscle attachments. Rostral scale movements are powered by, first, retractions of the palato-pterygoid bar, mediated by a ligament that connects the anterior end of the palatine to the transverse process of the premaxilla and, second, by contraction of a previously undescribed muscle slip of the m. retractor pterygoidei that inserts on the skin at the edge of the rostral scale. In derived snakes, palatomaxillary movements are highly conserved and power prey capture and transport behaviors. Aspidelaps scutatus has co-opted those mechanisms for the unrelated function of burrowing without compromising the original feeding functions, showing the potential for evolution of functional innovations in highly conserved systems. © 2017 Wiley Periodicals, Inc.

  4. Multiband observations of the Crab Nebula

    International Nuclear Information System (INIS)

    Krassilchtchikov, A M; Bykov, A M; Castelletti, G M; Dubner, G M; Kargaltsev, O Yu; Pavlov, G G

    2017-01-01

    Results of simultaneous imaging of the Crab Nebula in the radio (JVLA), optical ( HST ), and X-ray ( Chandra ) bands are presented. The images show a variety of small-scale structures, including wisps mainly located to the north-west of the pulsar and knots forming a ring-like structure associated with the termination shock of the pulsar wind. The locations of the structures in different bands do not coincide with each other. (paper)

  5. CMS distributed data analysis with CRAB3

    Science.gov (United States)

    Mascheroni, M.; Balcas, J.; Belforte, S.; Bockelman, B. P.; Hernandez, J. M.; Ciangottini, D.; Konstantinov, P. B.; Silva, J. M. D.; Ali, M. A. B. M.; Melo, A. M.; Riahi, H.; Tanasijczuk, A. J.; Yusli, M. N. B.; Wolf, M.; Woodard, A. E.; Vaandering, E.

    2015-12-01

    The CMS Remote Analysis Builder (CRAB) is a distributed workflow management tool which facilitates analysis tasks by isolating users from the technical details of the Grid infrastructure. Throughout LHC Run 1, CRAB has been successfully employed by an average of 350 distinct users each week executing about 200,000 jobs per day. CRAB has been significantly upgraded in order to face the new challenges posed by LHC Run 2. Components of the new system include 1) a lightweight client, 2) a central primary server which communicates with the clients through a REST interface, 3) secondary servers which manage user analysis tasks and submit jobs to the CMS resource provisioning system, and 4) a central service to asynchronously move user data from temporary storage in the execution site to the desired storage location. The new system improves the robustness, scalability and sustainability of the service. Here we provide an overview of the new system, operation, and user support, report on its current status, and identify lessons learned from the commissioning phase and production roll-out.

  6. No pain, no gain: Male plasticity in burrow digging according to female rejection in a sand-dwelling wolf spider.

    Science.gov (United States)

    Carballo, Matilde; Baldenegro, Fabiana; Bollatti, Fedra; Peretti, Alfredo V; Aisenberg, Anita

    2017-07-01

    Behavioral plasticity allows individuals to reversibly respond to short-term variations in their ecological and social environment in order to maximize their fitness. Allocosa senex is a burrow-digging spider that inhabits the sandy coasts of South America. This species shows a reversal in typical sex roles expected in spiders: females are wanderers that visit males at their burrows and initiate courtship. They prefer males with long burrows for mating, and males prefer virgin over mated females. We tested whether female sexual rejection induced males to enlarge their burrows and if female reproductive status affected males' responses. We exposed males who had constructed burrows to: a) virgin females or b) mated females, (n=16 for each category). If female rejection occurred, we repeated the trial 48h later with the same female. As control, we maintained a group of males without female exposure (unexposed group, n=32). Rejected males enlarged their burrows more frequently and burrows were longer compared to unexposed males. However, frequency and length of enlargement did not differ according to female reproductive status. Males of A. senex showed plasticity in digging behavior in response to the availability of females, as a way to maximize the possibilities of future mating. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. The Porcelain Crab Transcriptome and PCAD, the Porcelain Crab Microarray and Sequence Database

    Energy Technology Data Exchange (ETDEWEB)

    Tagmount, Abderrahmane; Wang, Mei; Lindquist, Erika; Tanaka, Yoshihiro; Teranishi, Kristen S.; Sunagawa, Shinichi; Wong, Mike; Stillman, Jonathon H.

    2010-01-27

    Background: With the emergence of a completed genome sequence of the freshwater crustacean Daphnia pulex, construction of genomic-scale sequence databases for additional crustacean sequences are important for comparative genomics and annotation. Porcelain crabs, genus Petrolisthes, have been powerful crustacean models for environmental and evolutionary physiology with respect to thermal adaptation and understanding responses of marine organisms to climate change. Here, we present a large-scale EST sequencing and cDNA microarray database project for the porcelain crab Petrolisthes cinctipes. Methodology/Principal Findings: A set of ~;;30K unique sequences (UniSeqs) representing ~;;19K clusters were generated from ~;;98K high quality ESTs from a set of tissue specific non-normalized and mixed-tissue normalized cDNA libraries from the porcelain crab Petrolisthes cinctipes. Homology for each UniSeq was assessed using BLAST, InterProScan, GO and KEGG database searches. Approximately 66percent of the UniSeqs had homology in at least one of the databases. All EST and UniSeq sequences along with annotation results and coordinated cDNA microarray datasets have been made publicly accessible at the Porcelain Crab Array Database (PCAD), a feature-enriched version of the Stanford and Longhorn Array Databases.Conclusions/Significance: The EST project presented here represents the third largest sequencing effort for any crustacean, and the largest effort for any crab species. Our assembly and clustering results suggest that our porcelain crab EST data set is equally diverse to the much larger EST set generated in the Daphnia pulex genome sequencing project, and thus will be an important resource to the Daphnia research community. Our homology results support the pancrustacea hypothesis and suggest that Malacostraca may be ancestral to Branchiopoda and Hexapoda. Our results also suggest that our cDNA microarrays cover as much of the transcriptome as can reasonably be captured in

  8. Potential Impact of Submarine Power Cables on Crab Harvest

    Science.gov (United States)

    Bull, A. S.; Nishimoto, M.

    2016-02-01

    Offshore renewable energy installations convert wave or wind energy to electricity and transfer the power to shore through transmission cables laid on or buried beneath the seafloor. West coast commercial fishermen, who harvest the highly prized Dungeness crab (Metacarcinus magister) and the rock crab (Cancer spp.), are concerned that the interface of crabs and electromagnetic fields (EMF) from these cables will present an electrified fence on the seafloor that their target resource will not cross. Combined with the assistance of professional fishermen, submarine transmission cables that electrify island communities and offshore oil platforms in the eastern Pacific provide an opportunity to test the harvest of crab species across power transmission cables. In situ field techniques give commercial crab species a choice to decide if they will cross fully energized, EMF emitting, power transmission cables, in response to baited traps. Each independent trial is either one of two possible responses: the crab crosses the cable to enter a trap (1) or the crab does not cross the cable to enter a trap (0). Conditions vary among sample units by the following categorical, fixed factors (i.e., covariates) of cable structure (buried or unburied); direction of cable from crab position (west or east, north or south); time and season. A generalized linear model is fit to the data to determine whether any of these factors affect the probability of crabs crossing an energized cable to enter baited traps. Additionally, the experimental design, aside from the number of runs (set of sample trials) and the dates of the runs, is the same in the Santa Barbara Channel for rock crab and Puget Sound for Dungeness crab, and allows us to compare the capture rates of the two species in the two areas. We present preliminary results from field testing in 2015.

  9. 50 CFR 680.6 - Crab economic data report (EDR).

    Science.gov (United States)

    2010-10-01

    ... sales gross revenue. CR fishery code, pounds sold, and gross revenue. (iii) CDQ crab lease costs. CR... sales, gross revenue. CR fishery code, species code, pounds sold, and gross revenue; (iii) CDQ and IFQ... materials, equipment and supplies; re-packing costs, broker fees and promotions for BSAI crab sales (by CR...

  10. Geographic Variation in Camouflage Specialization by a Decorator Crab.

    Science.gov (United States)

    Stachowicz, John J; Hay, Mark E

    2000-07-01

    In North Carolina, the decorator crab Libinia dubia camouflages almost exclusively with the chemically noxious alga Dictyota menstrualis. By placing this alga on its carapace, the crab behaviorally sequesters the defensive chemicals of the plant and gains protection from omnivorous consumers. However, Dictyota is absent north of North Carolina, whereas Libinia occurs as far north as New England. Crabs from three northern locations where Dictyota is absent (Rhode Island, Connecticut, and New Jersey) camouflaged to match their environment, rather than selectively accumulating any one species. When D. menstrualis was offered to crabs from northern sites, they did not distinguish between it and other seaweeds for camouflage, whereas crabs from Alabama and two locations in North Carolina used D. menstrualis almost exclusively. In addition, in winter and spring, when Dictyota was seasonally absent in North Carolina, Libinia selectively camouflaged with the sun sponge Hymeniacidon heliophila, which was chemically unpalatable to local fishes. Thus, southern crabs were consistent specialists on chemically defended species for camouflage, while northern crabs were more generalized. The geographic shift in crab behavior away from specialization coincides with a reported decrease in both total predation pressure and the frequency of omnivorous consumers. These shifts in the nature and intensity of predation pressure may favor different camouflage strategies (generalist vs. specialist), contributing to the observed geographic differences in camouflage behavior.

  11. Effect of Mudflat Trampling on Activity of Intertidal Crabs

    Science.gov (United States)

    Kim, Tae Won; Kim, Sanha; Lee, Jung-Ah

    2018-03-01

    Many people visit intertidal mudflats to collect bait and seafood, or for eco-tourism and recreation, and as a consequence trample on the mudflats frequently. Trampling would not be life threatening to most animals in the intertidal flats as they have evolved hiding behavior to escape predation. However, what is the effect of trampling on the behavior of intertidal animals? In this study, the effect of mudflat trampling on the activity of crabs (e.g. fiddler crabs, sentinel crabs) living on the mudflat was explored. The number of crabs active on the mudflat surface in experimental plots (1.5 × 1.5 m2) before and after (10 min. and 30 min.) trampling of three different intensities (Heavy trampling = 60 steps; Moderate trampling = 20 steps; and No trampling) was compared in two different mudflat systems. After trampling, the number of crabs active on the surface decreased and was significantly lower than that of control plots. The more intensively trampled the mudflat was, the fewer crabs were active on the mudflat surface. Surprisingly, the number of active crabs did not recover even 30 min. after trampling. The results clearly support the hypothesis that trampling can severely interfere with the behavior of crabs living on intertidal mudflats.

  12. A documentation on burrows in hard substrates of ferromanganese crusts and associated soft sediments from the Central Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Banerjee, R

    , which are extensively bioturbated. Both the ferromanganese-coated and uncoated relict burrows have been collected from the same locality. Mobile epibenthic megafauna, e.g. molluscs, echinoderms, etc. seem to be main bioturbating organisms. The adjacent...

  13. Water pumping and analysis of flow in burrowing zoobenthos - a short overview

    DEFF Research Database (Denmark)

    Riisgård, Hans Ulrik; Larsen, Poul Scheel

    2005-01-01

    with the measuring of water pumping and the analysis of flow generated by burrowing deposit- and filter-feeding zoobenthos in order to determine the type of pump and mechanisms involved, flow rate, pump pressure, and pumping power. The practical use of fluid mechanical principles is examined, and it is stressed......-feeding animals. In stagnant situations the near-bottom water may be depleted of food particles, depending on the population filtration rate and the intensity of the biomixing induced by the filtering activity. But moderate currents and the biomixing can presumably generate enough turbulence to facilitate mixing...... of water layers at the sea bed with the layers above where food particle concentrations are relatively higher. Following a brief summary of types of burrowing benthic animals, common methods for measuring pumping rates are described along with examples. For estimating the required pump pressure, biofluid...

  14. Black-footed ferrets and recreational shooting influence the attributes of black-tailed prairie dog burrows

    Science.gov (United States)

    Biggins, Dean E.; Ramakrishnan, Shantini; Goldberg, Amanda R.; Eads, David A.

    2012-01-01

    Black-tailed prairie dogs (Cynomys ludovicianus) plug burrows occupied by black-footed ferrets (Mustela nigripes), and they also plug burrows to entomb dead prairie dogs. We further evaluated these phenomena by sampling connectivity and plugging of burrow openings on prairie dog colonies occupied by ferrets, colonies where recreational shooting was allowed, and colonies with neither shooting nor ferrets. We counted burrow openings on line surveys and within plots, classified surface plugging, and used an air blower to examine subsurface connectivity. Colonies with ferrets had lower densities of openings, fewer connected openings (suggesting increased subsurface plugging), and more surface plugs compared to colonies with no known ferrets. Colonies with recreational shooting had the lowest densities of burrow openings, and line-survey data suggested colonies with shooting had intermediate rates of surface plugging. The extent of surface and subsurface plugging could have consequences for the prairie dog community by changing air circulation and escape routes of burrow systems and by altering energetic relationships. Burrow plugging might reduce prairie dogs' risk of predation by ferrets while increasing risk of predation by American badgers (Taxidea taxus); however, the complexity of the trade-off is increased if plugging increases the risk of predation on ferrets by badgers. Prairie dogs expend more energy plugging and digging when ferrets or shooting are present, and ferrets increase their energy expenditures when they dig to remove those plugs. Microclimatic differences in plugged burrow systems may play a role in flea ecology and persistence of the flea-borne bacterium that causes plague (Yersinia pestis).

  15. Effects of pocket gopher burrowing on cesium-133 distribution on engineered test plots

    International Nuclear Information System (INIS)

    Gonzales, G.J.; Saladen, M.T.; Hakonson, T.E.

    1995-01-01

    Very low levels of radionuclides exist on soil surfaces. Biological factors including vegetation and animal burrowing can influence the fate of these surface contaminants. Animal burrowing introduces variability in radionuclide migration that confounds estimation of nuclide migration pathways, risk assessment, and assessment of waste burial performance. A field study on the surface and subsurface erosional transport of surface-applied 133 Cs as affected by pocket gopher (Thomomys bottae) burrowing was conducted on simulated waste landfill caps at the Los Alamos National Laboratory in north central New Mexico. Surface loss of Cs, adhered to five soil particle size ranges, was measured several times over an 18-mo period while simulated rainfalls were in progress. Gophers reduced Cs surface loss by significant amounts, 43%. Cesium surface loss on plots with only gophers was 0.8 kg totalled for the study period. This compared with 1.4 kg for control plots, 0.5 kg for vegetated plots, and 0.2 kg for plots with both gophers and vegetation. The change in Cs surface loss over time was significant (P -1 ). Vegetation-bearing plots bad significant more total subsurface Cs (μ = 1.7 g kg -1 ) than plots without vegetation (μ = 0.8 g kg -1 ). An average of 97% of the subsurface Cs in plots with vegetation was located in the upper 15 cm of soil (SDR1 + SDR2) compared with 67% for plots without vegetation. Vegetation moderated the influence of gopher activity on the transport of Cs to soil subsurface, and stabilized subsurface Cs by concentrating it in the rhizosphere. Gopher activity may have caused Cs transport to depths below that sampled, 30 cm. The results provide distribution coefficients for models of contaminant migration where animal burrowing occurs. 35 refs., 2 figs., 3 tabs

  16. Burrowing by Sailfin Catfish (Pterygoplichthys sp.): A Potential Cause of Erosion in Disturbed Environments

    Science.gov (United States)

    2014-03-01

    originates at a large levee, which was built to create a water retention (to control excess water) and water bird management area. The levee and canal...each sample was dried in stainless steel trays in a 60 °C convection oven . Two methods of quantitative analysis were performed to determine the...ERDC/TN ANSRP-14-1 March 2014 Approved for public release; distribution is unlimited. Burrowing by Sailfin Catfish (Pterygoplichthys sp.): A

  17. Burrowing Owl and Other Migratory Bird Mitigation for a Runway Construction Project at Edwards AFB

    OpenAIRE

    Hoehn, Amber L.; Hagan, Mark; Bratton, Mark

    2009-01-01

    Edwards Air Force Base (AFB) scheduled the construction of a runway in the spring of 2007. The runway would be in an area that contained migratory birds and their habitat. The construction project would be near Edwards AFB main runway and had the potential not only to impact species protected under the Migratory Bird Treaty Act (MBTA), including the burrowing owl (Athene cunicularia), but also to increase bird and wildlife–aircraft strike hazards in the active flightline areas. To discourage ...

  18. Razor clam to RoboClam: burrowing drag reduction mechanisms and their robotic adaptation

    International Nuclear Information System (INIS)

    Winter, A G; V; Dorsch, D S; Slocum, A H; Hosoi, A E; Deits, R L H

    2014-01-01

    Estimates based on the strength, size, and shape of the Atlantic razor clam (Ensis directus) indicate that the animal's burrow depth should be physically limited to a few centimeters; yet razor clams can dig as deep as 70 cm. By measuring soil deformations around burrowing E. directus, we have found the animal reduces drag by contracting its valves to initially fail, and then fluidize, the surrounding substrate. The characteristic contraction time to achieve fluidization can be calculated directly from soil properties. The geometry of the fluidized zone is dictated by two commonly-measured geotechnical parameters: coefficient of lateral earth pressure and friction angle. Calculations using full ranges for both parameters indicate that the fluidized zone is a local effect, occurring between 1–5 body radii away from the animal. The energy associated with motion through fluidized substrate—characterized by a depth-independent density and viscosity—scales linearly with depth. In contrast, moving through static soil requires energy that scales with depth squared. For E. directus, this translates to a 10X reduction in the energy required to reach observed burrow depths. For engineers, localized fluidization offers a mechanically simple and purely kinematic method to dramatically reduce energy costs associated with digging. This concept is demonstrated with RoboClam, an E. directus-inspired robot. Using a genetic algorithm to find optimal digging kinematics, RoboClam has achieved localized fluidization burrowing performance comparable to that of the animal, with a linear energy-depth relationship, in both idealized granular glass beads and E. directus' native cohesive mudflat habitat. (paper)

  19. Long-term population dynamics of a managed burrowing owl colony

    Science.gov (United States)

    Barclay, John H.; Korfanta, Nicole M.; Kauffman, Matthew J.

    2011-01-01

    We analyzed the population dynamics of a burrowing owl (Athene cunicularia) colony at Mineta San Jose International Airport in San Jose, California, USA from 1990-2007. This colony was managed by using artificial burrows to reduce the occurrence of nesting owls along runways and within major airport improvement projects during the study period. We estimated annual reproduction in natural and artificial burrows and age-specific survival rates with mark-recapture techniques, and we estimated the relative contribution of these vital rates to population dynamics using a life table response experiment. The breeding colony showed 2 distinct periods of change: high population growth from 7 nesting pairs in 1991 to 40 pairs in 2002 and population decline to 17 pairs in 2007. Reproduction was highly variable: annual nesting success (pairs that raised =1 young) averaged 79% and ranged from 36% to 100%, whereas fecundity averaged 3.36 juveniles/pair and ranged from 1.43 juveniles/pair to 4.54 juveniles/pair. We estimated annual adult survival at 0.710 during the period of colony increase from 1996 to 2001 and 0.465 during decline from 2002 to 2007, but there was no change in annual survival of juveniles between the 2 time periods. Long-term population growth rate (lambda) estimated from average vital rates was lambdaa=1.072 with lambdai=1.288 during colony increase and lambdad=0.921 (DELTA lambda=0.368) during decline. A life table response experiment showed that change in adult survival rate during increasing and declining phases explained more than twice the variation in growth rate than other vital rates. Our findings suggest that management and conservation of declining burrowing owl populations should address factors that influence adult survival.

  20. Identification of irradiated crab using EPR

    Energy Technology Data Exchange (ETDEWEB)

    Maghraby, A. [Radiation Dosimetry Department, National Institute for Standards (NIS), Ministry of Scientific Research, Haram, 12211- Giza, P.O. Box: 136 (Egypt)]. E-mail: maghrabism@yahoo.com

    2007-02-15

    EPR spectroscopy is a fast and powerful technique for the identification of irradiated food. Crab exoskeleton was divided into six parts: dactyl, cheliped, carapace, apron, swimming legs, and walking legs. Samples of the exoskeleton were prepared and irradiated to Cs-137 gamma radiation in the range (1.156-5.365 kGy). EPR spectra of unirradiated as well as irradiated samples were recorded and analyzed. Response to gamma radiation was plotted for each part of the exoskeleton, dactyl was found to be the most sensitive part, followed by the apron (38%), cheliped (37%), walking legs (30%), swimming legs (24%), and carapace (21%) relative to the dactyl response.

  1. Identification of irradiated crab using EPR

    International Nuclear Information System (INIS)

    Maghraby, A.

    2007-01-01

    EPR spectroscopy is a fast and powerful technique for the identification of irradiated food. Crab exoskeleton was divided into six parts: dactyl, cheliped, carapace, apron, swimming legs, and walking legs. Samples of the exoskeleton were prepared and irradiated to Cs-137 gamma radiation in the range (1.156-5.365 kGy). EPR spectra of unirradiated as well as irradiated samples were recorded and analyzed. Response to gamma radiation was plotted for each part of the exoskeleton, dactyl was found to be the most sensitive part, followed by the apron (38%), cheliped (37%), walking legs (30%), swimming legs (24%), and carapace (21%) relative to the dactyl response

  2. ELEMENT MASSES IN THE CRAB NEBULA

    Energy Technology Data Exchange (ETDEWEB)

    Sibley, Adam R.; Katz, Andrea M.; Satterfield, Timothy J.; Vanderveer, Steven J.; MacAlpine, Gordon M. [Department of Physics and Astronomy, Trinity University, San Antonio, TX 78212 (United States)

    2016-10-01

    Using our previously published element abundance or mass-fraction distributions in the Crab Nebula, we derived actual mass distributions and estimates for overall nebular masses of hydrogen, helium, carbon, nitrogen, oxygen and sulfur. As with the previous work, computations were carried out for photoionization models involving constant hydrogen density and also constant nuclear density. In addition, employing new flux measurements for [Ni ii]  λ 7378, along with combined photoionization models and analytic computations, a nickel abundance distribution was mapped and a nebular stable nickel mass estimate was derived.

  3. Distribution of the Chuckwalla, Western Burrowing Owl, and Six Bat Species on the Nevada Test Site

    Energy Technology Data Exchange (ETDEWEB)

    Cathy A. Willis

    1997-05-01

    Field Surveys were conducted in 1996 to determine the current distribution of several animal species of concern on the Nevada Test Site (NTS). They included the chuckwall (Sauromalus obesus), western burrowing owl (Speotyto cunicularia), and six species of bats. Nineteen chuckwallas and 118 scat locations were found during the chuckwalla field study. Eighteen western burrowing owls were found at 12 sighting locations during the 1996 field study. Of the eleven bat species of concern which might occur on the NTS, five, and possibly six, were captured during this survey. The U.S. Department of Energy, Nevada Operations Office, takes certain management actions to protect and conserve the chuckwalla, western burrowing owl, and bats on the NTS. These actions are described and include: (1) conducting surveys at sites of proposed land-disturbing activities (2) altering projects whenever possible to avoid or minimize impacts to these species (3) maintaining a geospatial database of known habitat for species of concern (4) sharing sighting and trap location data gathered on the NTS with other local land and resource managers, and (5) conducting periodic field surveys to monitor these species distribution and relative abundance on the NTS.

  4. Regional and Seasonal Diet of the Western Burrowing Owl in South-Central Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Derek B. Hall, Paul D. Greger, Jeffrey R. Rosier

    2009-04-01

    We examined diets of Western Burrowing Owls (Athene cunicularia hypugaea) based on contents of pellets and large prey remains collected year-round at burrows in each of the 3 regions in south central Nevada (Mojave Desert, Great Basin Desert, and Transition region). The most common prey items, based on percent frequency of occurrence, were crickets and grasshoppers, beetles, rodents, sun spiders, and scorpions. The most common vertebrate prey was kangaroo rats (Dipodomys spp.). True bugs (Hemiptera), scorpions, and western harvest mice (Reithrodontomys megalotis) occurred most frequently in pellets from the Great Basin Desert region. Kangaroo rats (Dipodomys spp.) and pocket mice (Perognathinae) were the most important vertebrate prey items in the Transition and Mojave Desert regions, respectively. Frequency of occurrence of any invertebrate prey was high (>80%) in samples year-round but dropped in winter samples, with scorpions and sun spiders exhibiting the steepest declines. Frequency of occurrence of any vertebrate prey peaked in spring samples, was intermediate for winter and summer samples, and was lowest in fall samples. With the possible exception of selecting for western harvest mice in the Great Basin Desert region, Western Burrowing Owls in our study appeared to be opportunistic foragers with a generalist feeding strategy.

  5. N2 production and fixation in deep-tier burrows of Squilla empusa in muddy sediments of Great Peconic Bay

    Science.gov (United States)

    Waugh, Stuart; Aller, Robert C.

    2017-11-01

    Global marine N budgets often show deficits due to dominance of benthic N2 production relative to pelagic N2 fixation. Recent studies have argued that benthic N2 fixation in shallow water environments has been underestimated. In particular, N2 fixation associated with animal burrows may be significant as indicated by high rates of N2 fixation reported in muddy sands populated by the ghost shrimp, Neotrypaea californiensis (Bertics et al., 2010). We investigated whether N2 fixation occurs at higher rates in the burrow-walls of the deep-burrowing ( 0.5-4 m) mantis shrimp, Squilla empusa, compared to ambient, estuarine muds and measured seasonal in-situ N2 concentrations in burrow-water relative to bottom-water. Acetylene reduction assays showed lower N2 fixation in burrow-walls than in un-populated sediments, likely due to inhibitory effects of O2 on ethylene production. Dissolved N2 was higher in burrow-water than proximate bottom-water at all seasons, demonstrating a consistent balance of net N2 production relative to fixation in deep-tier biogenic structures.

  6. Comparison of three quick methods to estimate crab size in the land crabs Cardisoma guanhumi Latreille, 1825 and Ucides cordatus (Crustacea: Brachyura: Gecarcinidae and Ucididae

    Directory of Open Access Journals (Sweden)

    Carlos Alberto Carmona-Suárez

    2012-03-01

    Full Text Available Quick, reliable and non destructive methods are necessary to estimate size structure on commercial land crabs, in order to acquire relevant information concerning the health of their populations. Cardisoma guanhumi and Ucides cordatus are two land crabs that are exploited at a high scale and also in an artisan way in the Caribbean area and in the coasts of Brazil, which populations are endangered due to uncontrolled exploitation. The purpose of this work is to provide various methods to estimate indirectly crab body size. Sampling was carried out in Carenero (C. guanhumi and Cumaná (U. cordatus (Venezuela. For each species, three methods were used to measure burrow diameter (Vernier, internal spring caliper and photograph, and these were correlated with real body size of the crabs. Model II linear regression analyzes, i.e. Ordinary Least Squares and Mayor Axis, were used to build and test the performance of forecasting models. Cardisoma guanhumi showed a high bivariate data dispersion using Vernier and photo measuring methods, increasing these towards larger animals. Less dispersion was achieved with the spring caliper method; this resulted in the most accurate measurements of indirectly estimated body size in C. guanhumi (r²= 0.61, whereas Vernier measurements were the least precise. On the other hand, all three methods gave reliable estimates for U. cordatus, being the Vernier method the most accurate (r²= 0.71. However, in both species, all forecasting equations overestimated the size of smaller crabs (those below the mean but underestimated the size of larger crabs. Nevertheless, all three methods were statistically significant for each of the species, and looking at the above mentioned underand overestimations, they can serve as reliable and fast non-destructive tools to be used by resource managers and field biologists to acquire size structure information concerning these two species. Vernier and internal spring caliper methods are

  7. Are vent crab behavioral preferences adaptations for habitat choice?

    Science.gov (United States)

    Dahms, Hans-Uwe; Tseng, Li-Chun; Hwang, Jiang-Shiou

    2017-01-01

    Hydrothermal vent organisms are adapted to their extreme and patchily distributed habitats. They are expected to have evolved mechanisms that keep them in their specific habitation. Since little is known about the recruitment or habitat selection of HV organisms such as brachyurans, we examined the properties of several hydrothermal vent-associated cues on the behavior of the hydrothermal vent (HV) crab Xenograpsus testudinatus in the laboratory that were contrasted by the offering of non-vent cues. This crab species is endemic and dominates the vent fauna of Turtle Island off the NE coast of Taiwan. HV crabs were separately and in combination offered the following vent-specific cues: (1) sulfuric sediment, (3) air-bubbling, (4) elevated temperature, (5) dead settled zooplankton, (7) other crabs, and (8) shade. The non-vent-specific cues were: (2) quarz sediment, (6) dead fish, (8) light. These cues were provided on either side of a two-choice chamber. The movement of individual crabs was monitored: as initial and final choices, and as the proportion of time the crabs spent in each compartment (resident time). Cues were offered alone and no such cue as a control in the same set-up. Sulfuric sediments and dead fish were significantly more attractive to females, and other crabs irrespective of gender were significantly more attractive to males. When compared to expected distributions, crabs, irrespective of gender, significantly avoided light and tended to select other crabs, air-bubbling, sulfuric sediment, elevated temperature, dead fish, dead zooplankton, and quarz sediments in the order of decreasing importance. Data do not support the hypothesis that dead settled zooplankton was particularly attractive nor that the other gender was selected. A combination of several vent-associated cues (sulfuric sediment, elevated temperature, air-bubbling) facilitated the strongest attraction to the crabs as reflected by all response variables. The 'first choice' responses

  8. AFSC/RACE/SAP/Long: Data from: Effects of Ocean Acidification on Juvenile Red King Crab (Paralithodes camtschaticus) and Tanner Crab (Chionoecetes bairdi) Growth, Condition, Calcification, and Survival

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set is the results of a laboratory experiment. Juvenile red king crab and Tanner crab were reared in individual containers for nearly 200 days in flowing...

  9. M10.3.4: CLIC crab cavity specifications completed

    CERN Document Server

    Dexter, A; Ambattu, P; Shinton, I; Jones, R

    2010-01-01

    The starting point of Sub-task 2 is to document the currently anticipated requirements for the CLIC crab cavity system. This milestone concerns completion of the basic specifications for the CLIC crab cavity system. This comprises kick, power requirement, phase and amplitude stability, technology choice, and RF layout. The wakefield calculations of a baseline CLIC cavity will be used to estimate the required damping of the higher order modes as well as other special modes in crab cavities (the lower and same order modes).

  10. CLIC CRAB CAVITY SPECIFICATIONS MILESTONE: M10.3.4

    CERN Document Server

    Ambattu, P; Dexter, A; Jones, R; McIntosh, P; Shinton, I

    2010-01-01

    The starting point of Sub-task 2 is to document the currently anticipated requirements for the CLIC crab cavity system. This milestone concerns completion of the basic specifications for the CLIC crab cavity system. This comprises kick, power requirement, phase and amplitude stability, technology choice, and RF layout. The wakefield calculations of a baseline CLIC cavity will be used to estimate the required damping of the higher order modes as well as other special modes in crab cavities (the lower and same order modes).

  11. Thermal specialization across large geographical scales predicts the resilience of mangrove crab populations to global warming

    KAUST Repository

    Fusi, Marco; Giomi, Folco; Babbini, Simone; Daffonchio, Daniele; Mcquaid, Christopher D.; Porri, Francesca; Cannicci, Stefano

    2014-01-01

    The broad prediction that ectotherms will be more vulnerable to climate change in the tropics than in temperate regions includes assumptions about centre/edge population effects that can only be tested by within-species comparisons across wide latitudinal gradients. Here, we investigated the thermal vulnerability of two mangrove crab species, comparing populations at the centre (Kenya) and edge (South Africa) of their distributions. At the same time, we investigated the role of respiratory mode (water- versus air-breathing) in determining the thermal tolerance in amphibious organisms. To do this, we compared the vulnerability to acute temperature fluctuations of two sympatric species with two different lifestyle adaptations: the free living Perisesarma guttatum and the burrowing Uca urvillei, both pivotal to the ecosystem functioning of mangroves. The results revealed the air-breathing U. urvillei to be a thermal generalist with much higher thermal tolerances than P. guttatum. Importantly, however, we found that, while U. urvillei showed little difference between edge and centre populations, P. guttatum showed adaptation to local conditions. Equatorial populations had elevated tolerances to acute heat stress and mechanisms of partial thermoregulation, which make them less vulnerable to global warming than temperate conspecifics. The results reveal both the importance of respiratory mode to thermal tolerance and the unexpected potential for low latitude populations/species to endure a warming climate. The results also contribute to a conceptual model on the latitudinal thermal tolerance of these key species. This highlights the need for an integrated population-level approach to predict the consequences of climate change. © 2014 The Authors.

  12. Thermal specialization across large geographical scales predicts the resilience of mangrove crab populations to global warming

    KAUST Repository

    Fusi, Marco

    2014-11-18

    The broad prediction that ectotherms will be more vulnerable to climate change in the tropics than in temperate regions includes assumptions about centre/edge population effects that can only be tested by within-species comparisons across wide latitudinal gradients. Here, we investigated the thermal vulnerability of two mangrove crab species, comparing populations at the centre (Kenya) and edge (South Africa) of their distributions. At the same time, we investigated the role of respiratory mode (water- versus air-breathing) in determining the thermal tolerance in amphibious organisms. To do this, we compared the vulnerability to acute temperature fluctuations of two sympatric species with two different lifestyle adaptations: the free living Perisesarma guttatum and the burrowing Uca urvillei, both pivotal to the ecosystem functioning of mangroves. The results revealed the air-breathing U. urvillei to be a thermal generalist with much higher thermal tolerances than P. guttatum. Importantly, however, we found that, while U. urvillei showed little difference between edge and centre populations, P. guttatum showed adaptation to local conditions. Equatorial populations had elevated tolerances to acute heat stress and mechanisms of partial thermoregulation, which make them less vulnerable to global warming than temperate conspecifics. The results reveal both the importance of respiratory mode to thermal tolerance and the unexpected potential for low latitude populations/species to endure a warming climate. The results also contribute to a conceptual model on the latitudinal thermal tolerance of these key species. This highlights the need for an integrated population-level approach to predict the consequences of climate change. © 2014 The Authors.

  13. Robotic crabs reveal that female fiddler crabs are sensitive to changes in male display rate.

    Science.gov (United States)

    Mowles, Sophie L; Jennions, Michael D; Backwell, Patricia R Y

    2018-01-01

    Males often produce dynamic, repetitive courtship displays that can be demanding to perform and might advertise male quality to females. A key feature of demanding displays is that they can change in intensity: escalating as a male increases his signalling effort, but de-escalating as a signaller becomes fatigued. Here, we investigated whether female fiddler crabs, Uca mjoebergi , are sensitive to changes in male courtship wave rate. We performed playback experiments using robotic male crabs that had the same mean wave rate, but either escalated, de-escalated or remained constant. Females demonstrated a strong preference for escalating robots, but showed mixed responses to robots that de-escalated ('fast' to 'slow') compared to those that waved at a constant 'medium' rate. These findings demonstrate that females can discern changes in male display rate, and prefer males that escalate, but that females are also sensitive to past display rates indicative of prior vigour. © 2018 The Authors.

  14. Evolutionary history of true crabs (Crustacea: Decapoda: Brachyura) and the origin of freshwater crabs.

    Science.gov (United States)

    Tsang, Ling Ming; Schubart, Christoph D; Ahyong, Shane T; Lai, Joelle C Y; Au, Eugene Y C; Chan, Tin-Yam; Ng, Peter K L; Chu, Ka Hou

    2014-05-01

    Crabs of the infra-order Brachyura are one of the most diverse groups of crustaceans with approximately 7,000 described species in 98 families, occurring in marine, freshwater, and terrestrial habitats. The relationships among the brachyuran families are poorly understood due to the high morphological complexity of the group. Here, we reconstruct the most comprehensive phylogeny of Brachyura to date using sequence data of six nuclear protein-coding genes and two mitochondrial rRNA genes from more than 140 species belonging to 58 families. The gene tree confirms that the "Podotremata," are paraphyletic. Within the monophyletic Eubrachyura, the reciprocal monophyly of the two subsections, Heterotremata and Thoracotremata, is supported. Monophyly of many superfamilies, however, is not recovered, indicating the prevalence of morphological convergence and the need for further taxonomic studies. Freshwater crabs were derived early in the evolution of Eubrachyura and are shown to have at least two independent origins. Bayesian relaxed molecular methods estimate that freshwater crabs separated from their closest marine sister taxa ~135 Ma, that is, after the break up of Pangaea (∼200 Ma) and that a Gondwanan origin of these freshwater representatives is untenable. Most extant families and superfamilies arose during the late Cretaceous and early Tertiary.

  15. Interpopulational differences in the female reproductive cycle of the southwestern Atlantic estuarine crab Chasmagnathus granulatus Dana, 1851 (Brachyura: Grapsoidea: Varunidae

    Directory of Open Access Journals (Sweden)

    Romina B. Ituarte

    2006-12-01

    Full Text Available The female reproductive biology of Chasmagnathus granulatus Dana, a semiterrestrial burrowing crab endemic to the southwestern Atlantic, was compared in two contrasting coastal habitats: San Antonio (SA, marine and Mar Chiquita (MC, estuarial. Mature females were collected monthly for 1.5 years and the ovarian cycle was described using a qualitative scale. Gonadosomatic (GSI and hepatosomatic (HSI indexes were calculated. The highest GSI and HSI occurred early in the reproductive season in SA and during the non-reproductive season in MC. The beginning and duration of the reproductive season also differed between populations: it started later and was shorter in SA. In MC, secondary vitellogenesis continued when the reproductive season had finished, and the ovaries remained fully developed throughout the non-reproductive season (winter. Therefore, females of MC were ready to lay eggs as soon as spring environmental conditions appeared. However, SA females did not attain a fully developed ovary during winter. A limited food supply would restrict the available energy to complete secondary vitellogenesis at the end of the reproductive season in SA, after the last spawning. Thus, the vitellogenic cycle should be completed in the following spring, causing a delay in the beginning of the reproductive period. In addition, the higher temperature amplitude may cause the reproductive period in SA to end early.

  16. AFSC/REFM: BSAI Crab Economic Data Report

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Economic data collected for years 1998, 2001, 2004, and 2005 and onward for the BSAI Crab Economic Data Report (EDR). Reporting is required of any owner or...

  17. AFSC/RACE/SAP/Urban: Golden King Crab tagging

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is comprised of the records of individual male golden king crab (GKC) tagged at the Kodiak Laboratory. Initial size, shell condition and missing limbs was...

  18. Morphometric characteristics in the horseshoe crab Tachypleus gigas (Arthropoda: Merostomata)

    Digital Repository Service at National Institute of Oceanography (India)

    Vijayakumar, R.; Das, S.; Chatterji, A.; Parulekar, A.H.

    comparative morphometry. This study also emphasizes that care must be taken to apply morphometric for a uniform size group of horseshoe crab populations. It is known that the changes in the form of an animal cannot be described satisfactorily...

  19. Epibiotic community of the horseshoe crab Tachypleus gigas

    Digital Repository Service at National Institute of Oceanography (India)

    Patil, J.S.; Anil, A.C.

    Horseshoe crabs act as moving substrata for simple to complex communities of small marine organisms. Amplexed adult pairs migrate for breeding once every 2 weeks from deep waters towards nearshore waters during highest high tide. Female horseshoe...

  20. Crab cavities: Past, present, and future of a challenging device

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Q. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-05-03

    In two-ring facilities operating with a crossing-angle collision scheme, luminosity can be limited due to an incomplete overlapping of the colliding bunches. Crab cavities then are introduced to restore head-on collisions by providing the destined opposite deflection to the head and tail of the bunch. An increase in luminosity was demonstrated at KEKB with global crab-crossing, while the Large Hardron Collider (LHC) at CERN currently is designing local crab crossing for the Hi-Lumi upgrade. Future colliders may investigate both approaches. In this paper, we review the challenges in the technology, and the implementation of crab cavities, while discussing experience in earlier colliders, ongoing R&D, and proposed implementations for future facilities, such as HiLumi-LHC, CERN’s compact linear collider (CLIC), the international linear collider (ILC), and the electron-ion collider under design at BNL (eRHIC).

  1. Crab cavities: Past, present, and future of a challenging device

    International Nuclear Information System (INIS)

    Wu, Q.

    2015-01-01

    In two-ring facilities operating with a crossing-angle collision scheme, luminosity can be limited due to an incomplete overlapping of the colliding bunches. Crab cavities then are introduced to restore head-on collisions by providing the destined opposite deflection to the head and tail of the bunch. An increase in luminosity was demonstrated at KEKB with global crab-crossing, while the Large Hardron Collider (LHC) at CERN currently is designing local crab crossing for the Hi-Lumi upgrade. Future colliders may investigate both approaches. In this paper, we review the challenges in the technology, and the implementation of crab cavities, while discussing experience in earlier colliders, ongoing R&D, and proposed implementations for future facilities, such as HiLumi-LHC, CERN@@@s compact linear collider (CLIC), the international linear collider (ILC), and the electron-ion collider under design at BNL (eRHIC).

  2. Crab Cavities: Past, Present, and Future of a Challenging Device

    CERN Document Server

    Wu, Q

    2015-01-01

    In two-ring facilities operating with a crossing-angle collision scheme, luminosity can be limited due to an incomplete overlapping of the colliding bunches. Crab cavities then are introduced to restore head-on collisions by providing the destined opposite deflection to the head and tail of the bunch. An increase in luminosity was demonstrated at KEKB with global crab- crossing, while the Large Hardron Collider (LHC) at CERN currently is designing local crab crossing for the Hi-Lumi upgrade. Future colliders may investigate both approaches. In this paper, we review the challenges in the technology, and the implementation of crab cavities, while discussing experience in earlier colliders, ongoing R&D, and proposed implementations for future facilities, such as HiLumi-LHC, CERN’s compact linear collider (CLIC), the international linear collider (ILC), and the electronion collider under design at BNL (eRHIC).

  3. The surprising Crab pulsar and its nebula: a review.

    Science.gov (United States)

    Bühler, R; Blandford, R

    2014-06-01

    The Crab nebula and its pulsar (referred to together as 'the Crab') have historically played a central role in astrophysics. True to this legacy, several unique discoveries have been made recently. The Crab was found to emit gamma-ray pulsations up to energies of 400 GeV, beyond what was previously expected from pulsars. Strong gamma-ray flares, of durations of a few days, were discovered from within the nebula, while the source was previously expected to be stable in flux on these time scales. Here we review these intriguing and suggestive developments. In this context we give an overview of the observational properties of the Crab and our current understanding of pulsars and their nebulae.

  4. Eocene crabs (Crustacea, Brachyura) from Bonaire, Netherlands Antilles

    NARCIS (Netherlands)

    Collins, J.H.S.; Donovan, S.K.

    2005-01-01

    Recently discovered crabs from the Middle to Upper Eocene of northern Bonaire, Netherlands Antilles, include well-preserved carapaces of Montezumella rutteni Van Straelen, originally described from an incomplete holotype. The more comprehensive description of this species provided herein includes

  5. Breeding of the land crab Cardiosoma armatum (Herklots 1851) in ...

    African Journals Online (AJOL)

    SARAH

    2015-12-31

    Dec 31, 2015 ... Methodology and results: The experimental rearing system consisted of a series of seven rectangular pens ... Aquaculture in Benin, to inventory new species of ..... and availability of water in the net pens allowed crabs to.

  6. CLIC crab cavity design optimisation for maximum luminosity

    Energy Technology Data Exchange (ETDEWEB)

    Dexter, A.C., E-mail: a.dexter@lancaster.ac.uk [Lancaster University, Lancaster, LA1 4YR (United Kingdom); Cockcroft Institute, Daresbury, Warrington, WA4 4AD (United Kingdom); Burt, G.; Ambattu, P.K. [Lancaster University, Lancaster, LA1 4YR (United Kingdom); Cockcroft Institute, Daresbury, Warrington, WA4 4AD (United Kingdom); Dolgashev, V. [SLAC, Menlo Park, CA 94025 (United States); Jones, R. [University of Manchester, Manchester, M13 9PL (United Kingdom)

    2011-11-21

    The bunch size and crossing angle planned for CERN's compact linear collider CLIC dictate that crab cavities on opposing linacs will be needed to rotate bunches of particles into alignment at the interaction point if the desired luminosity is to be achieved. Wakefield effects, RF phase errors between crab cavities on opposing linacs and unpredictable beam loading can each act to reduce luminosity below that anticipated for bunches colliding in perfect alignment. Unlike acceleration cavities, which are normally optimised for gradient, crab cavities must be optimised primarily for luminosity. Accepting the crab cavity technology choice of a 12 GHz, normal conducting, travelling wave structure as explained in the text, this paper develops an analytical approach to optimise cell number and iris diameter.

  7. Emittance Growth due to Crab Cavity Ramping for LHC Beam-1 Lattice

    CERN Document Server

    Morita, A

    2008-01-01

    In LHC upgrade scenarios using global crab crossing, it is desired to turn on the crab cavity only at top energy. Turning on the crab cavity could increase the emittance of the stored beam, since the transverse kick of the crab cavity excites betatron oscillations. For a sufficiently slow ramping speed of the crab cavity voltage, however, the changes in z-dependent closed orbit are sufficiently adiabatic that the emittance growth becomes negligible. In order to determine the safe ramping speed of the LHC crab-cavity voltage, the dependence of the emittance growth on the ramping speed is estimated via a 6D particle-tracking simulation.

  8. Burrowing behavior of a deposit feeding bivalve predicts change in intertidal ecosystem state

    Directory of Open Access Journals (Sweden)

    Tanya Joan Compton

    2016-03-01

    Full Text Available Behavior has a predictive power that is often underutilized as a tool for signaling ecological change. The burrowing behavior of the deposit feeding bivalve Macoma balthica reflects a typical food-safety trade-off. The choice to live close to the sediment surface comes at a risk of predation and is a decision made when predation danger, food intake rates or future fitness prospects are low. In parts of the Dutch Wadden Sea, Macoma populations declined by 90% in the late 1990s, in parallel with large-scale mechanical cockle-dredging activities. During this decline, the burrowing depth of Macoma became shallow and was correlated with the population decline in the following year, indicating that it forecasted population change. Recently, there has been a series of large recruitment events in Macoma. According to the food-safety trade-off, we expected that Macoma should now live deeper, and have a higher body condition in association with this change in depth of living. Indeed, we observed that Macoma now lives deeper and that living depth in a given year forecasted population growth to the next year, especially in individuals larger than 14 mm. As living depth and body condition were strongly correlated in individuals larger than 14 mm, larger Macoma could be living deeper to protect their reproductive assets. Our results confirmed that burrowing depth signals impending population change and, together with body condition, can provide an early warning signal of ecological change. We suggest that population recovery is being driven by improved intertidal habitat quality in the Dutch Wadden Sea, rather than by the proposed climate-change related effects. This shift in ecosystem state is suggested to include the recovery of diatom habitat in the top layer of the sediment after cockle-dredging ended.

  9. Importance of agricultural landscapes to nesting burrowing owls in the Northern Great Plains, USA

    Science.gov (United States)

    Restani, M.; Davies, J.M.; Newton, W.E.

    2008-01-01

    Anthropogenic habitat loss and fragmentation are the principle factors causing declines of grassland birds. Declines in burrowing owl (Athene cunicularia) populations have been extensive and have been linked to habitat loss, primarily the decline of black-tailed prairie dog (Cynomys ludovicianus) colonies. Development of habitat use models is a research priority and will aid conservation of owls inhabiting human-altered landscapes. From 2001 to 2004 we located 160 burrowing owl nests on prairie dog colonies on the Little Missouri National Grassland in North Dakota. We used multiple linear regression and Akaike's Information Criterion to estimate the relationship between cover type characteristics surrounding prairie dog colonies and (1) number of owl pairs per colony and (2) reproductive success. Models were developed for two spatial scales, within 600 m and 2,000 m radii of nests for cropland, crested wheatgrass (Agropyron cristatum), grassland, and prairie dog colonies. We also included number of patches as a metric of landscape fragmentation. Annually, fewer than 30% of prairie dog colonies were occupied by owls. None of the models at the 600 m scale explained variation in number of owl pairs or reproductive success. However, models at the 2,000 m scale did explain number of owl pairs and reproductive success. Models included cropland, crested wheatgrass, and prairie dog colonies. Grasslands were not included in any of the models and had low importance values, although percentage grassland surrounding colonies was high. Management that protects prairie dog colonies bordering cropland and crested wheatgrass should be implemented to maintain nesting habitat of burrowing owls. ?? 2008 Springer Science+Business Media B.V.

  10. Habitat selection by two species of burrowing mayfly nymphs in the Les Cheneaux Islands region of northern Lake Huron

    Science.gov (United States)

    Blouin, Marc A.; Hudson, Patrick; Chriscinske, Margret

    2004-01-01

    This study focused primarily on the habitat preferences of Hexagenia limbata andEphemera simulans, two species prevalent in northern Lake Huron, to gain a better understanding of the key components that determined their distribution and abundance. Both species preferred habitats based upon depth and sediment type. In addition, the burrowing activity of H. limbata was examined using in-situ, underwater sampling techniques specifically designed for the study. SCUBA divers made resin casts and took clear sediment cores in order to study how the burrow densities of H. limbata related to the sediment: water volume ratios. H. limbata contributed to the bioturbation and sediment porosity in specific, fine-sediment habitats. Younger age classes of this species utilized the burrows of their larger cohorts, an adaptation that could allow for energy savings and optimized growth.

  11. Traces and burrowing behaviors of the Cicada nymph Cicadetta calliope: Neoichnology and paleoecological significance of extant soil-dwelling insects

    Science.gov (United States)

    Smith, J.J.; Hasiotis, S.T.

    2008-01-01

    This study documents the traces and burrowing behaviors of nymphs of the prairie cicada Cicadetta calliope (Hemiptera: Cicadidae), as observed in neoichnological experiments. Cicada nymphs were collected from the C horizons of sandy Fluvents along the Kansas River east of Lawrence, Kansas. The nymphs appeared to be fifth instars, 13-17 mm long and 6-7 mm wide. Nymphs were placed in plastic enclosures containing layers of colored, moist, very fine-grained sand. They burrowed immediately, excavating air-filled, sediment-enclosed cells between 20 mm and 40 mm long and averaging 9 mm wide. Burrowing was completed in three stages: (1) sediment in the forward portion of the cell was excavated and rolled into a ball with the forelimbs; (2) the nymph turned 180?? using a forward roll, and moved to the back of the cell; and (3) the sediment ball was pushed up against the back wall of the cell and kneaded with the forelimbs into a thin layer. Resulting burrow traces are sinuous and distinctly meniscate and demonstrate that insect larvae construct meniscate, backfilled burrows in well-drained terrestrial settings. Cicadetta calliope nymphs and their traces are excellent analogs for meniscate trace fossils commonly found in late Paleozoic-Cenozoic alluvial deposits and paleosols. Such meniscate trace fossils are useful for interpreting the paleoenvironment and paleohydrogeology of the units in which they are found. In addition, such backfilled burrows can be used to supplement the fossil record of cicada-like hemipterans, currently known only from the latest Permian to the Early Triassic. Copyright ?? 2008, SEPM (Society for Sedimentary Geology).

  12. The Analysis of Burrows Recognition Accuracy in XINJIANG'S Pasture Area Based on Uav Visible Images with Different Spatial Resolution

    Science.gov (United States)

    Sun, D.; Zheng, J. H.; Ma, T.; Chen, J. J.; Li, X.

    2018-04-01

    The rodent disaster is one of the main biological disasters in grassland in northern Xinjiang. The eating and digging behaviors will cause the destruction of ground vegetation, which seriously affected the development of animal husbandry and grassland ecological security. UAV low altitude remote sensing, as an emerging technique with high spatial resolution, can effectively recognize the burrows. However, how to select the appropriate spatial resolution to monitor the calamity of the rodent disaster is the first problem we need to pay attention to. The purpose of this study is to explore the optimal spatial scale on identification of the burrows by evaluating the impact of different spatial resolution for the burrows identification accuracy. In this study, we shoot burrows from different flight heights to obtain visible images of different spatial resolution. Then an object-oriented method is used to identify the caves, and we also evaluate the accuracy of the classification. We found that the highest classification accuracy of holes, the average has reached more than 80 %. At the altitude of 24 m and the spatial resolution of 1cm, the accuracy of the classification is the highest We have created a unique and effective way to identify burrows by using UAVs visible images. We draw the following conclusion: the best spatial resolution of burrows recognition is 1 cm using DJI PHANTOM-3 UAV, and the improvement of spatial resolution does not necessarily lead to the improvement of classification accuracy. This study lays the foundation for future research and can be extended to similar studies elsewhere.

  13. Seasonal temperature acclimatization in a semi-fossorial mammal and the role of burrows as thermal refuges

    Science.gov (United States)

    Rachlow, Janet L.; Chappell, Mark A.; Camp, Meghan J.; Johnson, Timothy R.; Shipley, Lisa A.; Paul, David R.; Forbey, Jennifer S.

    2018-01-01

    Small mammals in habitats with strong seasonal variation in the thermal environment often exhibit physiological and behavioral adaptations for coping with thermal extremes and reducing thermoregulatory costs. Burrows are especially important for providing thermal refuge when above-ground temperatures require high regulatory costs (e.g., water or energy) or exceed the physiological tolerances of an organism. Our objective was to explore the role of burrows as thermal refuges for a small endotherm, the pygmy rabbit (Brachylagus idahoensis), during the summer and winter by quantifying energetic costs associated with resting above and below ground. We used indirect calorimetry to determine the relationship between energy expenditure and ambient temperature over a range of temperatures that pygmy rabbits experience in their natural habitat. We also measured the temperature of above- and below-ground rest sites used by pygmy rabbits in eastern Idaho, USA, during summer and winter and estimated the seasonal thermoregulatory costs of resting in the two microsites. Although pygmy rabbits demonstrated seasonal physiological acclimatization, the burrow was an important thermal refuge, especially in winter. Thermoregulatory costs were lower inside the burrow than in above-ground rest sites for more than 50% of the winter season. In contrast, thermal heterogeneity provided by above-ground rest sites during summer reduced the role of burrows as a thermal refuge during all but the hottest periods of the afternoon. Our findings contribute to an understanding of the ecology of small mammals in seasonal environments and demonstrate the importance of burrows as thermal refuge for pygmy rabbits. PMID:29576977

  14. Real estate ads in Emei music frog vocalizations: female preference for calls emanating from burrows.

    Science.gov (United States)

    Cui, Jianguo; Tang, Yezhong; Narins, Peter M

    2012-06-23

    During female mate choice, both the male's phenotype and resources (e.g. his nest) contribute to the chooser's fitness. Animals other than humans are not known to advertise resource characteristics to potential mates through vocal communication; although in some species of anurans and birds, females do evaluate male qualities through vocal communication. Here, we demonstrate that calls of the male Emei music frog (Babina dauchina), vocalizing from male-built nests, reflect nest structure information that can be recognized by females. Inside-nest calls consisted of notes with energy concentrated at lower frequency ranges and longer note durations when compared with outside-nest calls. Centre frequencies and note durations of the inside calls positively correlate with the area of the burrow entrance and the depth of the burrow, respectively. When given a choice between outside and inside calls played back alternately, more than 70 per cent of the females (33/47) chose inside calls. These results demonstrate that males of this species faithfully advertise whether or not they possess a nest to potential mates by vocal communication, which probably facilitates optimal mate selection by females. These results revealed a novel function of advertisement calls, which is consistent with the wide variation in both call complexity and social behaviour within amphibians.

  15. Using ground penetrating radar in levee assessment to detect small scale animal burrows

    Science.gov (United States)

    Chlaib, Hussein K.; Mahdi, Hanan; Al-Shukri, Haydar; Su, Mehmet M.; Catakli, Aycan; Abd, Najah

    2014-04-01

    Levees are civil engineering structures built to protect human lives, property, and agricultural lands during flood events. To keep these important structures in a safe condition, continuous monitoring must be performed regularly and thoroughly. Small rodent burrows are one of the major defects within levees; however, their early detection and repair helps in protecting levees during flooding events. A set of laboratory experiments was conducted to analyze the polarity change in GPR signals in the presence of subsurface voids and water-filled cavities. Ground Penetrating Radar (GPR) surveys using multi frequency antennas (400 MHz and 900 MHz) were conducted along an 875 meter section of the Lollie Levee near Conway, Arkansas, USA, to assess the levee's structural integrity. Many subsurface animal burrows, water-filled cavities, clay clasts, and metallic objects were investigated and identified. These anomalies were located at different depths and have different sizes. To ground truth the observations, hand dug trenches were excavated to confirm several anomalies. Results show an excellent match between GPR interpreted anomalies and the observed features. In-situ dielectric constant measurements were used to calculate the feature depths. The results of this research show that the 900 MHz antenna has more advantages over the 400 MHz antenna.

  16. From LZ77 to the run-length encoded burrows-wheeler transform, and back

    DEFF Research Database (Denmark)

    Policriti, Alberto; Prezza, Nicola

    2017-01-01

    The Lempel-Ziv factorization (LZ77) and the Run-Length encoded Burrows-Wheeler Transform (RLBWT) are two important tools in text compression and indexing, being their sizes z and r closely related to the amount of text self-repetitiveness. In this paper we consider the problem of converting the t......(r + z) words of working space. Note that r and z can be constant if the text is highly repetitive, and our algorithms can operate with (up to) exponentially less space than naive solutions based on full decompression.......The Lempel-Ziv factorization (LZ77) and the Run-Length encoded Burrows-Wheeler Transform (RLBWT) are two important tools in text compression and indexing, being their sizes z and r closely related to the amount of text self-repetitiveness. In this paper we consider the problem of converting the two...... representations into each other within a working space proportional to the input and the output. Let n be the text length. We show that RLBWT can be converted to LZ77 in O(n log r) time and O(r) words of working space. Conversely, we provide an algorithm to convert LZ77 to RLBWT in O(n(log r + log z)) time and O...

  17. Effect of lunar periodicity on the abundance of crabs from the Goa Coast

    Digital Repository Service at National Institute of Oceanography (India)

    Chatterji, A; Ansari, Z.A; Ingole, B.S.; Sreepada, R.A; Kanti, A; Parulekar, A

    Lunar periodicity showed a significant influence on the occurrence of edible crabs (@iPortunus pelagicus, Charybdis cruciata and Portunus sanguinolentus@@). High density of these crabs was recorded in the trawl catches during full moon and new moon...

  18. AFSC/RACE/SAP/Long: Data from: Embryo development in golden king crab, Lithodes aequispina.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data from this study, describes embryo development in Golden king crab, Lithodes aequispinus. Six female multiparous golden king crab were captured from the...

  19. Spawning migration of the horseshoe crab, Tachypleus gigas (Muller), in relation to lunal cycle

    Digital Repository Service at National Institute of Oceanography (India)

    Chatterji, A.; Rathod, V.; Parulekar, A.H.

    Effects of lunar phases and tidal height on the spawning migration of the horseshoe crab, Tachypleus gigas, along the northeastern coast of India were studied. Mature pairs of crabs migrate towards the shore and build their nests in sandy beaches...

  20. Maine belowground marsh destruction from the European green crab documented by computer-aided tomography

    Science.gov (United States)

    Invasive European green crab (Carcinus maenus) populations have exploded with devastating losses to Maine’s intertidal resources including soft-shell clams, eelgrass beds, and salt marshes. This project quantified the green crab abundance in three different marsh locations ...

  1. Behavioral thermoregulation in Hemigrapsus nudus, the amphibious purple shore crab.

    Science.gov (United States)

    McGaw, I J

    2003-02-01

    The thermoregulatory behavior of Hemigrapsus nudus, the amphibious purple shore crab, was examined in both aquatic and aerial environments. Crabs warmed and cooled more rapidly in water than in air. Acclimation in water of 16 degrees C (summer temperatures) raised the critical thermal maximum temperature (CTMax); acclimation in water of 10 degrees C (winter temperatures) lowered the critical thermal minimum temperature (CTMin). The changes occurred in both water and air. However, these survival regimes did not reflect the thermal preferences of the animals. In water, the thermal preference of crabs acclimated to 16 degrees C was 14.6 degrees C, and they avoided water warmer than 25.5 degrees C. These values were significantly lower than those of the crabs acclimated to 10 degrees C; these animals demonstrated temperature preferences for water that was 17 degrees C, and they avoided water that was warmer than 26.9 degrees C. This temperature preference was also exhibited in air, where 10 degrees C acclimated crabs exited from under rocks at a temperature that was 3.2 degrees C higher than that at which the 16 degrees C acclimated animals responded. This behavioral pattern was possibly due to a decreased thermal tolerance of 16 degrees C acclimated crabs, related with the molting process. H. nudus was better able to survive prolonged exposure to cold temperatures than to warm temperatures, and there was a trend towards lower exit temperatures with the lower acclimation (10 degrees C) temperature. Using a complex series of behaviors, the crabs were able to precisely control body temperature independent of the medium, by shuttling between air and water. The time spent in either air or water was influenced more strongly by the temperature than by the medium. In the field, this species may experience ranges in temperatures of up to 20 degrees C; however, it is able to utilize thermal microhabitats underneath rocks to maintain its body temperature within fairly narrow

  2. Super-Acceleration in the Flaring Crab Nebula

    Energy Technology Data Exchange (ETDEWEB)

    Tavani, Marco, E-mail: marco.tavani@inaf.it

    2013-10-15

    The Crab Nebula continues to surprise us. The Crab system (energized by a very powerful pulsar at the center of the Supernova Remnant SN1054) is known to be a very efficient particle “accelerator” which can reach PeV energies. Today, new surprising data concerning the gamma-ray flares produced by the Crab Nebula challenge models of particle acceleration. The total energy flux from the Crab has been considered for many decades substantially stable at X-ray and gamma-ray energies. However, this paradigm was shattered by the AGILE discovery and Fermi confirmation in September 2010 of transient gamma-ray emission from the Crab. Indeed, we can state that four major flaring gamma-ray episodes have been detected by AGILE and Fermi during the period mid-2007/2012. During these events, transient particle acceleration occurs in a regime which apparently violates the MHD conditions and synchrotron cooling constraints. This fact justifies calling “super-acceleration” the mechanism which produces the “flaring Crab phenomenon”. Radiation between 50 MeV and a few GeV is emitted with a quite hard spectrum within a short timescale (hours-days), with no obvious relation with simultaneous optical and X-ray emissions in the inner Nebula. “Super-acceleration” implies overcoming synchrotron cooling by strong (and “parallel”) electric fields most likely produced by magnetic field reconnection within the pulsar wind outflow. This acceleration appears to be very efficient and, remarkably, limited by radiation reaction. It is not clear at the moment where in the Nebula this phenomenon occurs. An intense observational program is now focused on the Crab Nebula to resolve its most challenging mystery.

  3. The effects of two free-floating plants (Eichhornia crassipes and Pistia stratiotes on the burrow morphology and water quality characteristics of pond loach (Misgurnus anguillicaudatus habitat

    Directory of Open Access Journals (Sweden)

    Jinqing Wang

    2018-01-01

    Full Text Available Loach exhibit conspicuous drilling behaviors in the mud of shallow waters, yet their burrow morphology and the factors affecting this behavior have received little attention. We characterized the burrow morphology and water quality of the pond loach Misgurnus anguillicaudatus in three scenarios: in tanks without plants, tanks with the free-floating plant water hyacinth Eichhornia crassipes, and tanks with water lettuce Pistia stratiotes. Water hyacinth effectively removed water TN, COD, NO3-N and NH4-N, and water lettuce removed water TP and NH4-N. Water hyacinth and water lettuce markedly reduced water turbidity and DO, increased TOC and EC. Water hyacinth purified water more effectively than water lettuce, providing a suitable habitat for loach feeding, living and burrowing. The burrow structures were V-shaped, Y-shaped, inverted L-shaped, or complicated dendritic networks composed of multiple V shapes. The hyacinth treatment was characterized by the greatest burrow volume, length, depth, and structural complexity, but the opening size was reduced by dense root mat coverage. Burrows in the water lettuce treatment were characterized by intermediate volume, length, branches and sinuosity, but they had the largest opening and pit size. The control treatment had a flat bottom with the smallest, shortest burrows. This study indicates that free-floating plants improve habitat suitability and change burrow morphology and may be used to improve loach breeding methods.

  4. A study of burrow morphology in representative axiidean and gebiidean mud shrimps, from the Persian Gulf and Gulf of Oman, Iran

    Directory of Open Access Journals (Sweden)

    Vahid Sepahvand

    Full Text Available Mud shrimps (formerly Thalassinidea are common burrow dwelling decapod crustaceans in the littoral zone of the Persian Gulf and Gulf of Oman. Their burrow morphology was investigated using foam casting methods. The present study shows that the burrow morphology in Upogebia carinicauda is not consistent and the recorded variations are based on habitat type and some physical characteristics of sediments. Adult burrow morphology in sandy-muddy substrate with shells, and boulder field habitats were Y-shaped and complex burrows of horizontal channels with turning chambers and vertical connections to internal passages or crevices of boulders, respectively. In burrows of U. carinicauda, some narrow passages, connected to the upper part of adult burrows in sandy-muddy habitats, belong to juveniles. Another species, Neocallichirus jousseaumei was found under boulders in sandy-muddy habitats of the Gulf of Oman and Qeshm Island, Persian Gulf. Since this type of habitat is special in some features, no conspicuous ex-current openings (usually obvious as conical mounds of extruded sediment have been observed on the sediment surface; as these were hidden among the boulders surrounded by mixed sand and shells. The only method for observing this type of burrow was to remove the boulders by hand or lever.

  5. Effect of environmental conditions on variation in the sediment-water interface created by complex macrofaunal burrows on a tidal flat

    Science.gov (United States)

    Koo, Bon Joo; Kwon, Kae Kyoung; Hyun, Jung-Ho

    2007-11-01

    We quantified the increase in the sediment-water interface created by the burrowing activities of the resident macrofaunal community and its variation with respect to the physical conditions of the habitat on a tidal fat. We investigated environmental factors and dimensions of macrofaunal burrows with respect to tidal height and vegetation during spring and summer at three sites. A resin-casting method was used to quantify the dimensions of all burrows at each site. The dimensions of macrofaunal burrows varied both temporally and spatially and the increase in the sediment-water interface reached a maximum of 311%, ranging from 20 to 255% under different habitat conditions. The sediment-water interface depended on the duration of exposure resulting from tidal height, increased temperatures resulting from seasonality, and marsh plant density. Burrows were deeper and more expansive at both higher tidal levels and higher temperatures in summer. Burrow dimensions were sharply reduced with the disappearance of adult macrofauna in areas where the roots of the marsh plant Suaeda japonica were dense. The significance of this study lies in quantifying the burrow dimensions of the entire macrofaunal community, rather than just a single population, and confirming their spatial and temporal variation with respect to physical conditions of the habitat. Environmental factors responsible for variation in burrow dimensions are discussed.

  6. GROWTH PERFORMANCE AND MEAT QUALITY OF DOMESTICATED BLUE SWIMMING CRAB (Portunus pelagicus)

    OpenAIRE

    Fujaya, Yushinta; Trijuno, Dody Dharmawan; Aslamyah, Siti; Alam, Nur

    2015-01-01

    Blue Swimming Crab (Portunus pelagicus) is one of the commercial crabs traded widely around the world. But, crab aquaculture has not made a significant contribution in meeting the increasing overseas market demand. Some constraints in crab cultivation were high mortality, low and variable growth rate, and low of meat quality. The aims of this research were to produce a superior broodstock through domestication and selective breeding. Superior broodstock was expected to produce a high qual...

  7. Status of the mud crab fishery in Kenya: A review | Mirera | Western ...

    African Journals Online (AJOL)

    In Kenya, mud crabs are fished mainly by men and to a lesser extent by women and children due to the accessibility of the fishing areas by foot. This makes mud crabs a key fishery that is easily accessible for exploitation by most coastal artisanal fishers for subsistence and commercial purposes. Mud crabs have been a ...

  8. 76 FR 25545 - Safety Zone; Blue Crab Festival Fireworks Display, Little River, Little River, SC

    Science.gov (United States)

    2011-05-05

    ...-AA00 Safety Zone; Blue Crab Festival Fireworks Display, Little River, Little River, SC AGENCY: Coast... zone on the waters of Little River in Little River, South Carolina during the Blue Crab Festival... this rule because the Coast Guard did not receive notice of the Blue Crab Festival Fireworks Display...

  9. Habits and customs of crab catchers in southern Bahia, Brazil.

    Science.gov (United States)

    Firmo, Angélica M S; Tognella, Mônica M P; Tenório, Gabrielle D; Barboza, Raynner R D; Alves, Rômulo R N

    2017-08-23

    Brazilian mangrove forests are widely distributed along the coast and exploited by groups of people with customs and habits as diverse as the biology of the mangrove ecosystems. This study identifies different methods of extracting crabs that inhabit the mangrove belts; some of these activities, such as catching individual crabs by hand, are aimed at maintaining natural stocks of this species in Mucuri (south Bahia), Brazil. In the studied community, illegal hunting activities that violate Brazilian legislation limiting the use of tangle-netting in mangrove ecosystem were observed. According to our observations, fishermen, to catch individual crabs, use the tangle-netting technique seeking to increase income and are from families that have no tradition of extraction. This analysis leads us to conclude that catchers from economically marginalised social groups enter mangroves for purposes of survival rather than for purposes of subsistence, because the catching by tangle-netting is a predatory technique. Tangle-netting  technique increase caught but also increases their mortality rate. We emphasise that traditional catching methods are unique to Brazil and that manual capturing of crab should be preserved through public policies aimed at maintaining the crab population.

  10. Colour change and camouflage in juvenile shore crabs Carcinus maenas

    Directory of Open Access Journals (Sweden)

    Martin eStevens

    2014-05-01

    Full Text Available Camouflage is perhaps the most widespread anti-predator defense in nature, with many different types thought to exist. Of these, resembling the general color and pattern of the background (background matching is likely to be the most common. Background matching can be achieved by adaptation of individual appearance to different habitats or substrates, behavioral choice, and color change. Although the ability to change coloration for camouflage over a period of hours or days is likely to be widely found among animals, few studies have quantified this against different backgrounds. Here, we test whether juvenile shore crabs (Carcinus maenas are capable of color change for camouflage by placing them on either black or white (experiment 1 or red and green (experiment 2 backgrounds. We find that crabs are capable of significant changes in brightness, becoming lighter on white backgrounds and darker on black backgrounds. Using models of predator (avian vision, we show that these differences are large enough in many individuals to lead to perceptible changes in appearance. Furthermore, comparisons of crabs with the backgrounds show that changes are likely to lead to significant improvements in camouflage and potentially reduced detection probabilities. Crabs underwent some changes on the red and green backgrounds, but visual modeling indicated that these changes were very small and unlikely to be detectable. Our experiment shows that crabs are able to adjust their camouflage by changes in brightness over a period of hours, and that this could influence detection probability by predators.

  11. Lunar occultation observations of the Crab Nebula

    International Nuclear Information System (INIS)

    Maloney, F.P.

    1977-01-01

    Three lunar of occultations of the Crab Nebula were observed, two at 114 MHz and one at 26.3 MHz, during the 1974 series of events. The higher frequency observations were deconvolved of diffraction effects to yield four strip integrated brightness profiles of the Nebula, with an effective resolution of 30 arc-seconds. These four profiles were Fourier inverted and cleaned of sidelobe structure to synthesize a two-dimensional map of the Nebula. At 114 MHz, the Nebula is composed of a broad envelope of emission which contains several smaller sources. The attenuation of the low radio frequency radiation by the thermal hydrogen in the filaments is considered as a possible mechanism to explain these new data. The 26.3 MHz observations indicate the presence of a bright, localized source containing greater than 80% of the flux of the Nebula. The position of the source is confined by the data to a narrow strip centered at the pulsar position. Both sets of data are compared with past occultation observations

  12. PARTICLE REMOVAL RATES BY THE MUD SHRIMP UPOGEBIA PUGETTENSIS, ITS BURROW, AND A COMMENSAL CLAM: EFFECTS ON ESTUARINE PHYTOPLANKTON ABUNDANCE

    Science.gov (United States)

    The burrowing shrimp Upogebia pugettensis is an abundant intertidal inhabitant of Pacific Northwest bays and estuaries where it lives commensally with the bivalve Cryptomya californica. Suspension-feeding activities by the shrimp and by its commensal clam, as well as particle se...

  13. Distributional changes in the western Burrowing Owl (Athene cunicularia hypugaea) in North America from 1967 to 2008

    Science.gov (United States)

    Macias-Duarte, Alberto; Conway, Courtney J.

    2015-01-01

    The quantification of shifts in bird distributions in response to climate change provides an opportunity to gain a deeper understanding of the processes that influence species persistence. We used data from the North American Breeding Bird Survey (BBS) to document changes in the distributional limits of the western Burrowing Owl (Athene cunicularia hypugaea) from 1967 to 2008. We used logistic regression to model presence probability (p) as a function of longitude, latitude, and year. We modeled a linear trend in logit(p) through time with slope and intercept modeled as a double Fourier series of longitude and latitude. We found that the western Burrowing Owl has experienced an intriguing southward shift in the northern half of its breeding range, contrary to what is predicted by most species niche models and what has been observed for many other species in North America. The breeding range of the Burrowing Owl has been shrinking near its northern, western, and eastern edges. Our model detected the population declines that were observed in California and eastern Washington, in locations where maps based on route-specific estimating equations had predicted significant population increases. We suggest that the northern boundary of the breeding distribution of the western Burrowing Owl has contracted southward and the southern boundary of the species' breeding distribution has expanded southward into areas of northern Mexico that were formerly used only by wintering migrants.

  14. A maze-lover's dream: Burrow architecture, natural history and habitat characteristics of Ansell's mole-rat (Fukomys anselli)

    Czech Academy of Sciences Publication Activity Database

    Šklíba, J.; Mazoch, V.; Patzenhauerová, Hana; Hrouzková, E.; Lövy, M.; Kott, O.; Šumbera, R.

    2012-01-01

    Roč. 77, č. 6 (2012), s. 420-427 ISSN 1616-5047 R&D Projects: GA AV ČR IAA601410802 Institutional support: RVO:68081766 Keywords : Bathyergidae * Burrow system * Sociality * Habitat characteristics * Subterranean mammal * Fukomys anselli Subject RIV: EG - Zoology Impact factor: 1.246, year: 2012

  15. 76 FR 35772 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Science.gov (United States)

    2011-06-20

    ... Aleutian Islands Crab Rationalization Program AGENCY: National Marine Fisheries Service (NMFS), National... Tanner Crabs. Amendment 34 amends the Bering Sea and Aleutian Islands Crab Rationalization Program to... for the Crab Rationalization Program are available from the NMFS Alaska Region Web site at http...

  16. 76 FR 35781 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Science.gov (United States)

    2011-06-20

    ... Aleutian Islands Crab Rationalization Program; Amendment 37 AGENCY: National Marine Fisheries Service (NMFS... Tanner Crabs (FMP). This action amends the Bering Sea/Aleutian Islands Crab Rationalization Program by... Assessment prepared for the Crab Rationalization Program are available from the NMFS Alaska Region Web site...

  17. 76 FR 47155 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Science.gov (United States)

    2011-08-04

    ... the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab Rationalization Program... program for the Bering Sea/Aleutian Islands crab fisheries managed under the BSAI Crab Rationalization... Center Web site at http://www.afsc.noaa.gov/ . For further information on the Crab Rationalization...

  18. 75 FR 56485 - Groundfish Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea/Aleutian Islands Crab...

    Science.gov (United States)

    2010-09-16

    .../Aleutian Islands Crab Rationalization Program; Recordkeeping and Reporting AGENCY: National Marine... rule. SUMMARY: NMFS issues regulations to remove the Crab Rationalization Program requirements for.... Background The Crab Rationalization (CR) Program is a limited-access system that allocates crab managed under...

  19. Burrow characteristics of the co-existing sibling species Mus booduga and Mus terricolor and the genetic basis of adaptation to hypoxic/hypercapnic stress

    Directory of Open Access Journals (Sweden)

    Narayan Gopeshwar

    2009-04-01

    Full Text Available Abstract Background The co-existing, sibling species Mus booduga and Mus terricolor show a difference in site-preference for burrows. The former build them in flat portion of the fields while the latter make burrows in earthen mounds raised for holding water in cultivated fields. In northern India which experiences great variation in climatic condition between summer and winter, M. booduga burrows have an average depth of 41 cm, as against 30 cm in southern India with less climatic fluctuation. M. terricolor burrows are about 20 cm deep everywhere. The three chromosomal species M. terricolor I, II and III have identical burrows, including location of the nest which is situated at the highest position. In contrast, in M. booduga burrows, the nest is at the lowest position. Results The nest chamber of M. booduga is located at greater depth than the nest chamber of M. terricolor. Also, in the burrows of M. booduga the exchange of air takes place only from one side (top surface in contrast to the burrows of M. terricolor where air exchange is through three sides. Hence, M. booduga lives in relatively more hypoxic and hypercapnic conditions than M. terricolor. We observed the fixation of alternative alleles in M. booduga and M. terricolor at Superoxide dismutase-1 (Sod-1, Transferrin (Trf and Hemoglobin beta chain (Hbb loci. All the three are directly or indirectly dependent on oxygen concentration for function. In addition to these, there are differences in burrow patterns and site-preference for burrows suggesting difference in probable adaptive strategy in these co-existing sibling species. Conclusion The burrow structure and depth of nest of the chromosomal species M. terricolor I, II and III are same everywhere probably due to the recency of their evolutionary divergence. Moreover, there is lack of competition for the well-adapted 'microhabitats' since they are non-overlapping in distribution. However, the co-existing sibling species M. booduga

  20. Influence of land crabs Gecarcinus quadratus (Gecarcinidae on distributions of organic carbon and roots in a Costa Rican rain forest

    Directory of Open Access Journals (Sweden)

    Peter M Sherman

    2006-03-01

    Full Text Available In Costa Rica’s Corcovado National Park,the fossorial land crab, Gecarcinus quadratus (Gecarcinidae, densely populates (1-6 m-2 a region of forest extending from the Park’s Pacific coastline inland to ca.600 m. Throughout this coastal forest (‘crabzone’, crabs selectively forage for fallen leaves and relocate them to subterranean burrow chambers. Comparisons between surface soils (0 -15 cm sampled from the crabzone and forest lying immediately inland that is naturally devoid of crabs (‘crabless zone’ suggest that crabzone top soils contained less organic carbon and fewer fine and very fine roots. In contrast, soils sampled from 70 -100 cm depths in the crabzone contained twice the carbon of the crabless zone during the dry season but similar values during the wet season. Two years of experimental crab exclusion from 25 m² replicates established in the crabzone resulted in 16% more organic carbon content in surface soils relative to baseline conditions (n.s. and 22% more carbon than final control values (P El cangrejo Gecarcinus quadratus (Gecarcinidae habita madrigueras terrestres y afecta el retorno de carbón orgánico a los suelos de los bosques lluviosos al reducir la acumulación de hojarasca y alterar su proceso de descomposición. En el Parque Nacional Corcovado en Costa Rica, G. quadratus vive en altas densidades (de 1-6 cangrejos m-2 en una franja boscosa que se extiende desde la costa del Océano Pacífico hasta 600 m tierra adentro. En esta región de bosque costero (‘zona cangrejera’, los cangrejos buscan alimento selectivamente en la hojarasca, trasladando lo que recolectan a sus cuevas de más de 1 m de profundidad. Comparaciones entre la superficie de los suelos de la zona cangrejera y los de la región inmediata pero más lejana a la costa y sin cangrejos (‘zona no-cangrejera’, revelan que la capa superficial del suelo (a 10 cm en la zona cangrejera contiene 39% menos carbono orgánico, 72% menos ra

  1. Scent gland constituents of the Middle American burrowing python, Loxocemus bicolor (Serpentes: Loxocemidae).

    Science.gov (United States)

    Schulze, Thies; Weldon, Paul J; Schulz, Stefan

    2017-07-14

    Analysis by gas chromatography/mass spectrometry of the scent gland secretions of male and female Middle American burrowing pythons (Loxocemus bicolor) revealed the presence of over 300 components including cholesterol, fatty acids, glyceryl monoalkyl ethers, and alcohols. The fatty acids, over 100 of which were identified, constitute most of the compounds in the secretions and show the greatest structural diversity. They include saturated and unsaturated, unbranched and mono-, di-, and trimethyl-branched compounds ranging in carbon-chain length from 13 to 24. The glyceryl monoethers possess saturated or unsaturated, straight or methyl-branched alkyl chains ranging in carbon-chain length from 13 to 24. Alcohols, which have not previously been reported from the scent glands, possess straight, chiefly saturated carbon chains ranging in length from 13 to 24. Sex or individual differences in secretion composition were not observed. Compounds in the scent gland secretions of L. bicolor may deter offending arthropods, such as ants.

  2. The rhinoceros among Serpents: Comparative anatomy and experimental biophysics of Calabar burrowing python (Calabaria reinhardtii) skin.

    Science.gov (United States)

    Han, Dawei; Young, Bruce A

    2018-01-01

    The Calabar burrowing python (Calabaria reinhardtii) has a unique combination of marked thickness of the integumentary layers, a highly organized lamellate arrangement of the dermal collagen bundles, and a reduction in the size of the interscale hinge region of the integument. Biomechanical testing demonstrates that the skin of C. reinhardtii is more resistant to penetration than the skin of other snakes. The laminar arrangement of the collagen bundles provides for penetrative resistance, even while maintaining the flexibility characteristic of snake skin. Considering the life history of this species, it is hypothesized that the specialized integument of C. reinhardtii is a passive defensive mechanism against penetrative bites from maternal rodents and predators. © 2017 Wiley Periodicals, Inc.

  3. Effects of radiotransmitter necklaces on behaviors of adult male western burrowing owls

    Science.gov (United States)

    Chipman, E.D.; McIntyre, N.E.; Ray, J.D.; Wallace, M.C.; Boal, C.W.

    2007-01-01

    We studied the behavioral effects of necklace-style radiotransmitters on breeding male western burrowing owls (Athene cunicularia hypugaea) in 2 areas of northwestern Texas, USA, in 2004 and 2005. We tested the hypothesis that transmittered owls would spend time interacting with their necklaces and as a result spend less time in vigilance and resting activities than would nontransmittered owls. Nontransmittered owls (n = 6) spent significantly more time being vigilant (P = 0.007) than did transmittered owls (n = 3) in 2004, who spent significant amounts of time interacting with their necklaces. In 2005, behaviors of transmittered owls (n = 8) were significantly different (P of time interacting with their necklaces, they appeared to habituate to the presence of the transmitters within a relatively short period (<1 week), and necklaces did not affect survivorship or fitness in the short-term.

  4. Associational resistance protects mangrove leaves from crab herbivory

    Science.gov (United States)

    Erickson, Amy A.; Bell, Susan S.; Dawes, Clinton J.

    2012-05-01

    While associational defenses have been well documented in many plant and algal ecosystems, this study is the first to document associational resistance in mangroves. Mangrove tree crab (Aratus pisonii) density and herbivory on three life-stages of the red mangrove (Rhizophora mangle) were documented in pure red versus mixed-species and predominantly non-red mangrove stands containing black (Avicennia germinans) and white (Laguncularia racemosa) mangroves in 1999-2000 in Tampa Bay, Florida. This study first established that R. mangle is the focal species in the context of associational resistance because it is damaged more than either of the other mangrove species. Next, it was hypothesized that crab density and leaf damage on R. mangle would be lower when in mixed-species and predominantly non-red versus red mangrove stands. A non-significant trend suggested that crab density varies among stands, and crab damage on R. mangle leaves was significantly lower in mixed-species and non-red stands. Mechanisms to explain associational resistance were examined. Positive Pearson correlations between the percent of adult R. mangle in a stand and both crab density and R. mangle leaf damage provided support for the resource concentration hypothesis. Limited support was found for the attractant-decoy hypothesis because the total amount of damaged leaves of all mangrove species combined typically differed among stands, suggesting that crabs were not shifting to alternative mangrove species to offset reduced availability of R. mangle leaves. Finally, while R. mangle seedlings were shorter in non-red stands compared to others, intra-specific differences in R. mangle leaf chemistry and sclerophylly among stands failed to explain associational patterns. These combined results argue for the need for additional experiments to elucidate mechanisms responsible for defensive plant associations in mangrove ecosystems and to determine whether such associations could be of use in mangrove

  5. Patterns of surface burrow plugging in a colony of black-tailed prairie dogs occupied by black-footed ferrets

    Science.gov (United States)

    Eads, David E.; Biggins, Dean E.

    2012-01-01

    Black-tailed prairie dogs (Cynomys ludovicianus) can surface-plug openings to a burrow occupied by a black-footed ferret (Mustela nigripes). At a coarse scale, surface plugs are more common in colonies of prairie dogs occupied by ferrets than in colonies without ferrets. However, little is known about spatial and temporal patterns of surface plugging in a colony occupied by ferrets. In a 452-ha colony of black-tailed prairie dogs in South Dakota, we sampled burrow openings for surface plugs and related those data to locations of ferrets observed during spotlight surveys. Of 67,574 burrow openings in the colony between June and September 2007, 3.7% were plugged. In a colony-wide grid of 80 m × 80 m cells, the occurrence of surface plugging (≥1 opening plugged) was greater in cells used by ferrets (93.3% of cells) than in cells not observably used by ferrets (70.6%). Rates of surface plugging (percentages of openings plugged) were significantly higher in cells used by ferrets (median = 3.7%) than in cells without known ferret use (median = 3.2%). Also, numbers of ferret locations in cells correlated positively with numbers of mapped surface plugs in the cells. To investigate surface plugging at finer temporal and spatial scales, we compared rates of surface plugging in 20-m-radius circle-plots centered on ferret locations and in random plots 1–4 days after observing a ferret (Jun–Oct 2007 and 2008). Rates of surface plugging were greater in ferret-plots (median = 12.0%) than in random plots (median = 0%). For prairie dogs and their associates, the implications of surface plugging could be numerous. For instance, ferrets must dig to exit or enter plugged burrows (suggesting energetic costs), and surface plugs might influence microclimates in burrows and consequently influence species that cannot excavate soil (e.g., fleas that transmit the plague bacterium Yersinia pestis).

  6. Burrowing as a novel voluntary strength training method for mice: A comparison of various voluntary strength or resistance exercise methods.

    Science.gov (United States)

    Roemers, P; Mazzola, P N; De Deyn, P P; Bossers, W J; van Heuvelen, M J G; van der Zee, E A

    2018-04-15

    Voluntary strength training methods for rodents are necessary to investigate the effects of strength training on cognition and the brain. However, few voluntary methods are available. The current study tested functional and muscular effects of two novel voluntary strength training methods, burrowing (digging a substrate out of a tube) and unloaded tower climbing, in male C57Bl6 mice. To compare these two novel methods with existing exercise methods, resistance running and (non-resistance) running were included. Motor coordination, grip strength and muscle fatigue were measured at baseline, halfway through and near the end of a fourteen week exercise intervention. Endurance was measured by an incremental treadmill test after twelve weeks. Both burrowing and resistance running improved forelimb grip strength as compared to controls. Running and resistance running increased endurance in the treadmill test and improved motor skills as measured by the balance beam test. Post-mortem tissue analyses revealed that running and resistance running induced Soleus muscle hypertrophy and reduced epididymal fat mass. Tower climbing elicited no functional or muscular changes. As a voluntary strength exercise method, burrowing avoids the confounding effects of stress and positive reinforcers elicited in forced strength exercise methods. Compared to voluntary resistance running, burrowing likely reduces the contribution of aerobic exercise components. Burrowing qualifies as a suitable voluntary strength training method in mice. Furthermore, resistance running shares features of strength training and endurance (aerobic) exercise and should be considered a multi-modal aerobic-strength exercise method in mice. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Estimating population size of a nocturnal burrow-nesting seabird using acoustic monitoring and habitat mapping

    Directory of Open Access Journals (Sweden)

    Steffen Oppel

    2014-04-01

    Full Text Available Population size assessments for nocturnal burrow-nesting seabirds are logistically challenging because these species are active in colonies only during darkness and often nest on remote islands where manual inspections of breeding burrows are not feasible. Many seabird species are highly vocal, and recent technological innovations now make it possible to record and quantify vocal activity in seabird colonies. Here we test the hypothesis that remotely recorded vocal activity in Cory’s shearwater (Calonectris borealis breeding colonies in the North Atlantic increases with nest density, and combined this relationship with cliff habitat mapping to estimate the population size of Cory’s shearwaters on the island of Corvo (Azores. We deployed acoustic recording devices in 9 Cory’s shearwater colonies of known size to establish a relationship between vocal activity and local nest density (slope = 1.07, R2 = 0.86, p < 0.001. We used this relationship to predict the nest density in various cliff habitat types and produced a habitat map of breeding cliffs to extrapolate nest density around the island of Corvo. The mean predicted nest density on Corvo ranged from 6.6 (2.1–16.2 to 27.8 (19.5–36.4 nests/ha. Extrapolation of habitat-specific nest densities across the cliff area of Corvo resulted in an estimate of 6326 Cory’s shearwater nests (95% confidence interval: 3735–10,524. This population size estimate is similar to previous assessments, but is too imprecise to detect moderate changes in population size over time. While estimating absolute population size from acoustic recordings may not be sufficiently precise, the strong positive relationship that we found between local nest density and recorded calling rate indicates that passive acoustic monitoring may be useful to document relative changes in seabird populations over time.

  8. Polarization and emission geometry of the Crab pulsar

    International Nuclear Information System (INIS)

    Kaiyou Chen; Cheng Ho

    1993-01-01

    Optical emission of the Crab pulsar can best be understood as synchrotron radiation of relativistic particles from the outer magnetosphere of the neutron star. The outer gap model was developed specifically to address energy balance and double-pulsed emission (from optical to high-energy gamma-ray) of young pulsars like the Crab. In this paper, we present the polarization properties of the optical pulses calculated from the outer gap model. We found that the theoretical light curves exhibit the same qualitative behavior as observations

  9. Preliminary study on domestication of coconut crab (Birgus latro

    Directory of Open Access Journals (Sweden)

    . Sulistiono

    2007-07-01

    Full Text Available Preliminary study on domestication of coconut crab (Birgus latro had been done since June - November 2004 and December - 2005 February 2006.  Study was carried out in two locations namely Laboratory of Sekolah Tinggi Kelautan dan Perikanan, Palu to study adult crab, and Laboratory of Ecobiology of Faculty of Fisheries and Marine Science, Bogor Agricultural University to study crab in clomang stage.  Adult crabs were collected by using some fishing gears namely trap, net and directly using bamboo stick.  Domestication was done in rearing batch sized 1x1x1 m3 with artificial nests (30x15x15 cm3, and small batch for water (7x10x10 cm3.  While for clomang stage, crabs were reared in aquarium (80x40x40 cm3 with debris and small water batch.  Result showed that adult crab had a survival rate around 12.5-0%, and mortality around 50-87.5%.  A similar result was also in clomang stage, which was 12.5% for survival rate and 87.5% for mortality.  Adult coconut crab was preferred to feed coconut than other food likely vegetable and chick. Keywords: domestication, coconut crab, Birgus latro, food habit   ABSTRAK Penelitian awal mengenai kajian awal penangkaran kepiting kelapa (Birgus latro dilakukan pada bulan Juni - November 2004 dan Desember 2005 Februari 2006.  Pelaksanaan penelitian di lakukan di dua tempat, yaitu Laboratorium Sekolah Tinggi Kelautan dan Perikanan, Palu untuk percobaan kepiting dewasa, dan Laboratorium Ekobiologi Fakultas Perikanan dan Ilmu Kelautan IPB Bogor,  untuk percobaan kepiting tahap klomang.  Kepiting dewasa ditangkap dengan menggunakan beberapa peralatan a.l. perangkap, jaring dan secara langsung dengan tongkat.  Penangkaran dilakukan di bak-bak peliharaan berukuran 1x1x1 m3 yang dilengkapi dengan tempat persembunyian (30x15x15 cm3, dan bak kecil tempat air (7x10x10 cm3.  Sedangkan kepiting tahap klomang dipelihara di akuarium (80x40x40 cm3 yang diberi daun/serasah dan tempat air.  Hasil uji coba penangkaran

  10. Epizootiology of the parasitic dinoflagellate Hematodinium sp. in the American blue crab Callinectes sapidus.

    Science.gov (United States)

    Messick, G A; Shields, J D

    2000-11-14

    Hematodinium sp. is a parasitic dinoflagellate that infects and kills blue crabs Callinectes sapidus. Periodic outbreaks of dinoflagellate infections with subsequent high host mortalities prompted a study of the epizootiology and distribution of the crab pathogen. Hemolymph samples from over 13000 crabs were assessed for infections over 8 yr. Moderate to high prevalences were found at several locations along the Atlantic and Gulf coasts of the United States. In the coastal bays of Maryland and Virginia, prevalence followed a seasonal pattern, with a sharp peak in late autumn. Infections were significantly more prevalent in crabs measuring less than 30 mm carapace width; host sex did not influence prevalence. Prevalences were highest in crabs collected from salinities of 26 to 30%o; no infected crabs were found in salinities below 11%o. Intensity of infection did not vary among crab sizes, molt stages, or sexes. Naturally and experimentally infected crabs died over 35 and 55 d in captivity, with a mean time to death of approximately 13 and 42 d, respectively. Several other crustaceans, including gammaridean amphipods, xanthid (mud) crabs, and the green crab Carcinus maenus, were found with Hematodinium-like infections. Considering its widespread distribution and high pathogenicity, we suggest that Hematodinium sp. represents a significant threat to blue crab populations in high salinity estuaries along the Atlantic and Gulf coasts of the USA.

  11. The use of artificial crabs for testing predatory behavior and health in the octopus.

    Science.gov (United States)

    Amodio, Piero; Andrews, Paul; Salemme, Marinella; Ponte, Giovanna; Fiorito, Graziano

    2014-01-01

    The willingness of the cephalopod mollusc Octopus vulgaris to attack a live crab is traditionally used as a method to assess the overall health and welfare of octopuses in the laboratory. This method requires placing a crab in the home tank of an animal, measuring the time (latency) taken for the octopus to initiate an attack and withdrawing the crab immediately prior to capture. The same crab is commonly used to assess multiple octopuses as part of daily welfare assessment. Growing concern for the welfare of crustaceans and a review of all laboratory practices for the care and welfare of cephalopods following the inclusion of this taxon in 2010/63/EU prompted a study of the utility of an artificial crab to replace a live crab in the assessment of octopus health. On consecutive days O. vulgaris (N=21) were presented with a live, a dead or an artificial crab, and the latency to attack measured. Despite differences in the predatory performance towards the three different crab alternatives, octopuses readily attacked the artificial (and the dead) crab, showing that they can generalize and respond appropriately towards artificial prey. Researchers should consider using an artificial crab to replace the use of a live crab as part of the routine health assessment of O. vulgaris.

  12. Boxer crabs induce asexual reproduction of their associated sea anemones by splitting and intraspecific theft

    Directory of Open Access Journals (Sweden)

    Yisrael Schnytzer

    2017-01-01

    Full Text Available Crabs of the genus Lybia have the remarkable habit of holding a sea anemone in each of their claws. This partnership appears to be obligate, at least on the part of the crab. The present study focuses on Lybia leptochelis from the Red Sea holding anemones of the genus Alicia (family Aliciidae. These anemones have not been found free living, only in association with L. leptochelis. In an attempt to understand how the crabs acquire them, we conducted a series of behavioral experiments and molecular analyses. Laboratory observations showed that the removal of one anemone from a crab induces a “splitting” behavior, whereby the crab tears the remaining anemone into two similar parts, resulting in a complete anemone in each claw after regeneration. Furthermore, when two crabs, one holding anemones and one lacking them, are confronted, the crabs fight, almost always leading to the “theft” of a complete anemone or anemone fragment by the crab without them. Following this, crabs “split” their lone anemone into two. Individuals of Alicia sp. removed from freshly collected L. leptochelis were used for DNA analysis. By employing AFLP (Fluorescence Amplified Fragments Length Polymorphism it was shown that each pair of anemones from a given crab is genetically identical. Furthermore, there is genetic identity between most pairs of anemone held by different crabs, with the others showing slight genetic differences. This is a unique case in which one animal induces asexual reproduction of another, consequently also affecting its genetic diversity.

  13. The Crab Pulsar and Relativistic Wind

    Science.gov (United States)

    Coroniti, F. V.

    2017-12-01

    The possibility that the Crab pulsar produces a separated ion-dominated and pair-plasma-dominated, magnetically striped relativistic wind is assessed by rough estimates of the polar cap acceleration of the ion and electron primary beams, the pair production of secondary electrons and positrons, and a simple model of the near-magnetosphere-wind zone. For simplicity, only the orthogonal rotator is considered. Below (above) the rotational equator, ions (electrons) are accelerated in a thin sheath, of order (much less than) the width of the polar cap, to Lorentz factor {γ }i≈ (5{--}10)× {10}7({γ }e≈ {10}7). The accelerating parallel electric field is shorted out by ion-photon (curvature synchrotron) pair production. With strong, but fairly reasonable, assumptions, a set of general magnetic geometry relativistic wind equations is derived and shown to reduce to conservation relations that are similar to those of the wind from a magnetic monopole. The strength of the field-aligned currents carried by the primary beams is determined by the wind’s Alfvén critical point condition to be about eight times the Goldreich-Julian value. A simple model for the transition from the dipole region wind to the asymptotic monopole wind zone is developed. The asymptotic ratio of Poynting flux to ion (pair plasma) kinetic energy flux—the wind {σ }w∞ -parameter—is found to be of order {σ }w∞ ≈ 1/2({10}4). The far wind zone is likely to be complex, with the ion-dominated and pair-plasma-dominated magnetic stripes merging, and the oppositely directed azimuthal magnetic fields annihilating.

  14. Invasive ants compete with and modify the trophic ecology of hermit crabs on tropical islands.

    Science.gov (United States)

    McNatty, Alice; Abbott, Kirsti L; Lester, Philip J

    2009-05-01

    Invasive species can dramatically alter trophic interactions. Predation is the predominant trophic interaction generally considered to be responsible for ecological change after invasion. In contrast, how frequently competition from invasive species contributes to the decline of native species remains controversial. Here, we demonstrate how the trophic ecology of the remote atoll nation of Tokelau is changing due to competition between invasive ants (Anoplolepis gracilipes) and native terrestrial hermit crabs (Coenobita spp.) for carrion. A significant negative correlation was observed between A. gracilipes and hermit crab abundance. On islands with A. gracilipes, crabs were generally restricted to the periphery of invaded islands. Very few hermit crabs were found in central areas of these islands where A. gracilipes abundances were highest. Ant exclusion experiments demonstrated that changes in the abundance and distribution of hermit crabs on Tokelau are a result of competition. The ants did not kill the hermit crabs. Rather, when highly abundant, A. gracilipes attacked crabs by spraying acid and drove crabs away from carrion resources. Analysis of naturally occurring N and C isotopes suggests that the ants are effectively lowering the trophic level of crabs. According to delta(15) N values, hermit crabs have a relatively high trophic level on islands where A. gracilipes have not invaded. In contrast, where these ants have invaded we observed a significant decrease in delta(15) N for all crab species. This result concurs with our experiment in suggesting long-term exclusion from carrion resources, driving co-occurring crabs towards a more herbivorous diet. Changes in hermit crab abundance or distribution may have major ramifications for the stability of plant communities. Because A. gracilipes have invaded many tropical islands where the predominant scavengers are hermit crabs, we consider that their competitive effects are likely to be more prominent in

  15. Infusion of low dose glyceryl trinitrate has no consistent effect on burrowing behavior, running wheel activity and light sensitivity in female rats

    DEFF Research Database (Denmark)

    Christensen, Sarah Louise T; Petersen, Steffen; Sørensen, Dorte Bratbo

    2016-01-01

    . In the current paper we have studied the effect of glyceryl trinitrate infusion on three different rat behaviors. Methods: The stability of burrowing behavior, running wheel activity and light sensitivity towards repeated testing was evaluated also with respect to estrous cycle. Finally, the effect of glyceryl...... trinitrate on these behaviors in female rats was observed. Results: Burrowing behavior and running wheel activity were stable in the individual rat between experiments. The burrowing behavior was significantly affected by the stage of estrous cycle. The other assays were stable throughout the cycle. None...

  16. Hard X-ray Variations in the Crab Nebula

    Science.gov (United States)

    Wilson-Hodge, Colleen A.; Cherry, M. L.; Case, G. L.; Baumgartner, W. H.; Beklen, E.; Bhat, P. N.; Briggs, M. S.; Camero-Arranz, A.; Connaughton, V.; Finger, M. H.; hide

    2013-01-01

    In the first two years of science operations of the Fermi Gamma-ray Burst Monitor (GBM), August 2008 to August 2010, approximately 7% (70 mcrab) decline was discovered in the overall Crab Nebula flux in the 15 - 50 keV band, measured with the Earth occultation technique. This decline was independently confirmed with four other instruments: the RXTE/PCA, Swift/BAT, INTEGRAL/IBIS, and INTEGRAL/SPI. The pulsed flux measured with RXTE/PCA from 1999-2010 was consistent with the pulsar spin-down, indicating that the observed changes were nebular. From 2001 to 2010, the Crab nebula flux measured with RXTE/ PCA was particularly variable, changing by up to approximately 3.5% per year in the 15-50 keV band. These variations were confirmed with INTEGRAL/SPI starting in 2003, Swift/BAT starting in 2005, and Fermi GBM starting in 2008. Before 2001 and since 2010, the Crab nebula flux has appeared more stable, varying by less than 2% per year. I will present updated light curves in multiple energy bands for the Crab Nebula, including recent data from Fermi GBM, Swift/BAT, INTEGRAL and MAXI, and a 16-year long light curve from RXTE/PCA.

  17. Crab Hole Mosquito Blues—The Story

    Centers for Disease Control (CDC) Podcasts

    This podcast reports on a humorous song that takes a look at a very serious human and equine disease. Written and performed by the MARU Health Angels Band, Bill Dietz, director of the Division of Nutrition, Physical Activity and Obesity at CDC, talks about the song, "Crab Hole Mosquito Blues", and the history behind it.

  18. Multibaseline Observations of the Occultation of Crab Nebula by the ...

    Indian Academy of Sciences (India)

    tribpo

    Observations of the radio source Crab Nebula were made at the time of transit during. June 1986 and 1987. The fringe amplitude V(S) for a baseline S was calibrated using the corresponding baseline fringe amplitude of radio source 3C123 or 3C134 and normalised to the preoccultation value V(O). Normalised fringe ...

  19. Project "Flappy Crab": An Edu-Game for Music Learning

    Science.gov (United States)

    Cardoso Gomes, Cristina Maria; Guerreiro Figueiredo, Mauro Jorge; Bidarra, José; Cardoso Gomes, José Duarte

    2014-01-01

    This paper discusses some possibilities of gamification and remixing process for music education. Analyses also the concepts of gamification, mashup, remix and presents its possible usage in education--music teaching--through the development of the project/educational game "Flappy Crab". The article begins with a brief introduction to…

  20. Crab Nebula Variations in Hard X-rays

    Science.gov (United States)

    Wilson-Hodge, Colleen A.

    2012-01-01

    The Crab Nebula was surprisingly variable from 2001-2010, with less variability before 2001 and since mid-2010. We presented evidence for spectral softening from RXTE, Swift/BAT, and Fermi GBM during the mid-2008-2010 flux decline. We see no clear connections between the hard X-ray variations and the GeV flares

  1. The Crab nebula's ''wisps'' as shocked pulsar wind

    International Nuclear Information System (INIS)

    Gallant, Y.A.; Arons, J.; Langdon, A.B.

    1992-01-01

    The Crab synchrotron nebula has been successfully modelled as the post-shock region of a relativistic, magnetized wind carrying most of the spindown luminosity from the central pulsar. While the Crab is the best-studied example, most of the highest spindown luminosity pulsars are also surrounded by extended synchrotron nebulae, and several additional supernova remnants with ''plerionic'' morphologies similar to the Crab are known where the central object is not seen. All these objects have nonthermal, power-law spectra attributable to accelerated high-energy particles thought to originate in a Crab-like relativistic pulsar wind. However, proposed models have so far treated the wind shock as an infinitesimally thin discontinuity, with an arbitrarily ascribed particle acceleration efficiency. To make further progress, investigations resolving the shock structure seemed in order. Motivated by these considerations, we have performed ''particle-in-cell (PIC) simulations of perpendicularly magnetized shocks in electron-positron and electron-positron-ion plasmas. The shocks in pure electron-positron plasmas were found to produce only thermal distributions downstream, and are thus poor candidates as particle acceleration sites. When the upstream plasma flow also contained a smaller population of positive ions, however, efficient acceleration of positrons, and to a lesser extent of electrons, was observed in the simulations

  2. Crab spiders (Araeneae: Philodromidae, Thomisidae) of Ramsey County, Minnesota.

    Science.gov (United States)

    Daniel. T. Jennings; Bruce Cutler

    1996-01-01

    Crab spiders of 2 families, 10 genera, and 35 species were collected over a 31-year period in Ramsey County, Minnesota. Rarely collected species included Philodromus keyserlingi, Xysticus pellax, X. chippewa, X. banksi and X. alboniger. Identification source(s), season and collection frequency, and biology are summarized for each species.

  3. Reproduction in crabs: strategies, invasiveness and environmental influences thereon

    NARCIS (Netherlands)

    Brink, van den A.M.

    2013-01-01

    This thesis provides insights into the interconnectedness of crab reproductive biology, the selective forces leading to their development, the possible links to invasiveness and the influences of environmental factors thereon. The empirical data collected and presented in this thesis can be used

  4. The temporal behaviour of Taurus X-1 (the Crab Nebula)

    International Nuclear Information System (INIS)

    Davison, P.J.N.

    1975-01-01

    Copernicus data on Taurus X-1 and the Crab pulsar extending over a 2 1/2-yr period indicate that under normal conditions the source has a flux that is constant to within 2.5 per cent at the 90 per cent confidence level. The pulsed/total flux ratio also shows no significant changes during the same time. (author)

  5. Macro and Trace Element Accumulation in Edible Crabs and Frogs ...

    African Journals Online (AJOL)

    The tissue accumulation of five macroelements (Na, Mg, K, Ca, Fe) and twelve trace elements (Vd, Mn, Co, Ni, Cu, Zn, As, Se, Mo, Ag, Cd, Pb) were assessed in the organs of the edible frogs; Xenopus laevis and Rana esculentus, and whole body of the crab, Callinestes caught from Alaro Stream Floodplain (Ibadan, ...

  6. The osmoregulatory ability of three grapsoid crab species in relation ...

    African Journals Online (AJOL)

    The osmoregulatory abilities of the grapsoid crabs Cyclograpsus punctata, Sesarma catenata and Sesarma eulimene were studied comparatively in an attempt to explain, at least in part, their distribution in estuaries. Both survival and haemorymph osmotic pressure were used as indices of hyperosmotic regulatory ability.

  7. Temperature and salinity tolerance of adult hermit crabs, Diogenes ...

    African Journals Online (AJOL)

    1987-11-04

    Nov 4, 1987 ... estuary may not limit the distribution of hermit crabs. Because of their broad tolerance they should be able to survive near the head of the estuary. However, this continuous exposure to low salinity may be intolerable during moult and limit normal growth and metamorphosis, so although there may not be a.

  8. Mud Crab (Scylla serrata) Culture: Understanding the Technology in ...

    African Journals Online (AJOL)

    Abstract—A study was conducted in Mtwapa creek on the north coast Kenya, during 2005-2007 to evaluate the viability of pens and drive-in cages for mud crab (S. serrata) culture as a mangrove management strategy and alternative source of income for local communities. Other objectives were to assess the effectiveness ...

  9. The larval development of the red mangrove crab Sesarma meinerti ...

    African Journals Online (AJOL)

    The larval stages of the red mangrove crab Sesarma meinerti de Man were reared in the laboratory. Larval development consists of five zoeal stages and one megalopa. Zoeal development lasts an average of 25 days at 25°C. The external morphology of larvae is described in detail and their relationship with larvae of.

  10. Spatial and temporal patterns of subtidal and intertidal crabs excursions

    Science.gov (United States)

    Silva, A. C. F.; Boaventura, D. M.; Thompson, R. C.; Hawkins, S. J.

    2014-01-01

    Highly mobile predators such as fish and crabs are known to migrate from the subtidal zone to forage in the intertidal zone at high-tide. The extent and variation of these habitat linking movements along the vertical shore gradient have not been examined before for several species simultaneously, hence not accounting for species interactions. Here, the foraging excursions of Carcinus maenas (L.), Necora puber (Linnaeus, 1767) and Cancer pagurus (Linnaeus, 1758) were assessed in a one-year mark-recapture study on two replicated rocky shores in southwest U.K. A comparison between the abundance of individuals present on the shore at high-tide with those present in refuges exposed at low-tide indicated considerable intertidal migration by all species, showing strong linkage between subtidal and intertidal habitats. Estimates of population size based on recapture of marked individuals indicated that an average of ~ 4000 individuals combined for the three crab species, can be present on the shore during one tidal cycle. There was also a high fidelity of individuals and species to particular shore levels. Underlying mechanisms for these spatial patterns such as prey availability and agonistic interactions are discussed. Survival rates were estimated using the Cormack-Jolly-Seber model from multi-recapture analysis and found to be considerably high with a minimum of 30% for all species. Growth rates were found to vary intraspecifically with size and between seasons. Understanding the temporal and spatial variations in predation pressure by crabs on rocky shores is dependent on knowing who, when and how many of these commercially important crab species depend on intertidal foraging. Previous studies have shown that the diet of these species is strongly based on intertidal prey including key species such as limpets; hence intertidal crab migration could be associated with considerable impacts on intertidal assemblages.

  11. The largest glitch observed in the Crab pulsar

    Science.gov (United States)

    Shaw, B.; Lyne, A. G.; Stappers, B. W.; Weltevrede, P.; Bassa, C. G.; Lien, A. Y.; Mickaliger, M. B.; Breton, R. P.; Jordan, C. A.; Keith, M. J.; Krimm, H. A.

    2018-05-01

    We have observed a large glitch in the Crab pulsar (PSR B0531+21). The glitch occurred around MJD 58064 (2017 November 8) when the pulsar underwent an increase in the rotation rate of Δν = 1.530 × 10-5 Hz, corresponding to a fractional increase of Δν/ν = 0.516 × 10-6 making this event the largest glitch ever observed in this source. Due to our high-cadence and long-dwell time observations of the Crab pulsar we are able to partially resolve a fraction of the total spin-up of the star. This delayed spin-up occurred over a timescale of ˜1.7 days and is similar to the behaviour seen in the 1989 and 1996 large Crab pulsar glitches. The spin-down rate also increased at the glitch epoch by Δ \\dot{ν } / \\dot{ν } = 7 × 10^{-3}. In addition to being the largest such event observed in the Crab, the glitch occurred after the longest period of glitch inactivity since at least 1984 and we discuss a possible relationship between glitch size and waiting time. No changes to the shape of the pulse profile were observed near the glitch epoch at 610 MHz or 1520 MHz, nor did we identify any changes in the X-ray flux from the pulsar. The long-term recovery from the glitch continues to progress as \\dot{ν } slowly rises towards pre-glitch values. In line with other large Crab glitches, we expect there to be a persistent change to \\dot{ν }. We continue to monitor the long-term recovery with frequent, high quality observations.

  12. CRABS IN CRISIS:BIOGEOGRAPHIC DISTRIBUTIONS, ABUNDANCES, AND VULNERABILITIES TO CLIMATE CHANGE OF BRACHYURAN AND LITHODID CRABS FROM THE GULF OF CALIFORNIA TO THE BEAUFORT SEA

    Science.gov (United States)

    To predict the relative vulnerability of near-coastal species to climate change we analyzed the biogeographic and abundance patterns of the brachyuran or ‘True’ crabs (n=368) and lithodid or ‘King’ crabs (n=20) that are found in the twelve MEOW (“Mar...

  13. Synthesis of Pt nanoparticles and their burrowing into Si due to synergistic effects of ion beam energy losses

    Directory of Open Access Journals (Sweden)

    Pravin Kumar

    2014-10-01

    Full Text Available We report the synthesis of Pt nanoparticles and their burrowing into silicon upon irradiation of a Pt–Si thin film with medium-energy neon ions at constant fluence (1.0 × 1017 ions/cm2. Several values of medium-energy neon ions were chosen in order to vary the ratio of the electronic energy loss to the nuclear energy loss (Se/Sn from 1 to 10. The irradiated films were characterized using Rutherford backscattering spectroscopy (RBS, atomic force microscopy (AFM, scanning electron microscopy (SEM, X-ray diffraction (XRD and high resolution transmission electron microscopy (HRTEM. A TEM image of a cross section of the film irradiated with Se/Sn = 1 shows ≈5 nm Pt NPs were buried up to ≈240 nm into the silicon. No silicide phase was detected in the XRD pattern of the film irradiated at the highest value of Se/Sn. The synergistic effect of the energy losses of the ion beam (molten zones are produced by Se, and sputtering and local defects are produced by Sn leading to the synthesis and burrowing of Pt NPs is evidenced. The Pt NP synthesis mechanism and their burrowing into the silicon is discussed in detail.

  14. ECOBIOLOGICAL STUDY ON BURROWING MUD LOBSTER THALASSINA ANOMALA (HERBST, 1804 (DECAPODA : THALASSINIDEA IN THE INTERTIDAL MANGROVE MUDFLAT OF DELTAIC SUNDARBANS

    Directory of Open Access Journals (Sweden)

    S. K. Dubey

    2012-07-01

    Full Text Available Populations of mud lobster Thalassina anomala were studied on tidal flats in the Sagar island of Indian Sundarbans. Ecologically they are recognized as the 'friends of mangrove' and a 'Biological Marvel' of the system. They turn up the deep soil to the surface by regular night shift burrowing exercise and help to import aerated tidal water in the burrows 2 to 2.5 meter deep. They have extra ordinary morphological adaptation and structural changes and completely resort to detritivore diet. Being thigmotactic it seldom exposes to atmospheric oxygen and forms its palace underground with a central chamber having 5 to 6 radiated tunnels opening to the surface covered with earth mounds. It displays its engineering skill of bioturbation in tunneling. During tunneling the shrimp feeds on the mud packed with detritus and derived its required micronutrients. Being mud dwelling and mud eating habits, it's respiratory and food manipulating apparatus underwent transformations which demands intensive investigation. Thalassinid burrow associates comprising mieo and microorganisms also provide good subject of study of species specific interaction, exchanging of materials between associate partners.

  15. Incidence of plastic fragments among burrow-nesting seabird colonies on offshore islands in northern New Zealand.

    Science.gov (United States)

    Buxton, Rachel T; Currey, Caitlin A; Lyver, Philip O'B; Jones, Christopher J

    2013-09-15

    Marine plastic pollution is ubiquitous throughout the world's oceans, and has been found in high concentrations in oceanic gyres of both the northern and southern hemispheres. The number of studies demonstrating plastic debris at seabird colonies and plastic ingestion by adult seabirds has increased over the past few decades. Despite the recent discovery of a large aggregation of plastic debris in the South Pacific subtropical gyre, the incidence of plastics at seabird colonies in New Zealand is unknown. Between 2011 and 2012 we surveyed six offshore islands on the northeast coast of New Zealand's North Island for burrow-nesting seabird colonies and the presence of plastic fragments. We found non-research related plastic fragments (0.031 pieces/m(2)) on one island only, Ohinau, within dense flesh-footed shearwater (Puffinus carneipes) colonies. On Ohinau, we found a linear relationship between burrow density and plastic density, with 3.5 times more breeding burrows in areas with plastic fragments found. From these data we conclude that plastic ingestion is a potentially a serious issue for flesh-footed shearwaters in New Zealand. Although these results do not rule out plastic ingestion by other species, they suggest the need for further research on the relationship between New Zealand's pelagic seabirds and marine plastic pollution. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Failure to Burrow and Tunnel Reveals Roles for jim lovell in the Growth and Endoreplication of the Drosophila Larval Tracheae.

    Directory of Open Access Journals (Sweden)

    Fanli Zhou

    Full Text Available The Drosophila protein Jim Lovell (Lov is a putative transcription factor of the BTB/POZ (Bric- a-Brac/Tramtrack/Broad/ Pox virus and Zinc finger domain class that is expressed in many elements of the developing larval nervous system. It has roles in innate behaviors such as larval locomotion and adult courtship. In performing tissue-specific knockdown with the Gal4-UAS system we identified a new behavioral phenotype for lov: larvae failed to burrow into their food during their growth phase and then failed to tunnel into an agarose substratum during their wandering phase. We determined that these phenotypes originate in a previously unrecognized role for lov in the tracheae. By using tracheal-specific Gal4 lines, Lov immunolocalization and a lov enhancer trap line, we established that lov is normally expressed in the tracheae from late in embryogenesis through larval life. Using an assay that monitors food burrowing, substrate tunneling and death we showed that lov tracheal knockdown results in tracheal fluid-filling, producing hypoxia that activates the aberrant behaviors and inhibits development. We investigated the role of lov in the tracheae that initiates this sequence of events. We discovered that when lov levels are reduced, the tracheal cells are smaller, more numerous and show lower levels of endopolyploidization. Together our findings indicate that Lov is necessary for tracheal endoreplicative growth and that its loss in this tissue causes loss of tracheal integrity resulting in chronic hypoxia and abnormal burrowing and tunneling behavior.

  17. Role of burrowing activities of the Great Basin pocket mouse (Perognathus parvus) in the dispersal of radionuclides on a decommissioned pond

    International Nuclear Information System (INIS)

    Landeen, D.S.; Mitchell, R.M.

    1982-08-01

    The intrusion of waste burial sites by animals is a common occurrence at nuclear waste facilities. This study identifies parameters associated with burrowing activities of the Great Basin Pocket Mouse at the Hanford Site in southeastern Washington. The objectives of the study were to: (1) document and compare burrow depths on a control site and a decommissioned radioactive waste pond and (2) document 137 Cs concentrations in pocket mice and the soil mounds created by their burrowing activities. Pocket mice burrowed deeper in the backfilled burial site (anti x = 72 cm) than they did in the control site (anti x = 38 cm). The small amounts of 137 Cs found in the mice were an order of magnitude below what was present in the mounds. This indicates that the burrowing habits of these mice and subsequent mound construction may be more important in terms of radionuclide dispersal than the small amounts contained within their bodies. The 137 Cs values reported in the mice and mounds are below Rockwell Hanford Operations (Rockwell) surface soil contamination limits. Information received from test plots will be used in formulating appropriate control mechanisms which may be deployed in the future. In the interim, surface stabilization efforts are being conducted on waste sites to control and deter burrowing animals

  18. Isotopic signatures (13C/12C; 15N/14N) of blue penguin burrow soil invertebrates : carbon sources and trophic relationships

    International Nuclear Information System (INIS)

    Hawke, D.J.; Clark, J.M.

    2010-01-01

    Seabird burrows provide a soil environment for processing discards such as feathers and guano, hence constituting a primary interface between the sea and the land. This study involved collection and culturing of soil invertebrates from three blue penguin (Eudyptula minor) burrows, and examined their 13 C/ 12 C and 15 N/ 14 N isotopic composition in relation to potential burrow resources (terrestrial plant litter, burrow soil, guano, blue penguin feathers). Two taxa (cerylonid beetles and small tineid moth larvae) had a depleted 13 C/ 12 C indicative of a level of dependence on C from terrestrial soil. Tineid moth larvae (Monopis crocicapitella and (or) M. ethelella) substantially increased their 13 C/ 12 C enrichment during development, implying increasing dependence on marine C. Remaining taxa, both decomposers and predators, had 13 C/ 12 C intermediate between guano and feathers. Larval and emergent fleas had the most enriched 13 C/ 12 C , indicative of a greater dependence on feather C and the likelihood of co-processing with guano. Pseudoscorpions and histerid beetles had overlapping isotopic enrichments implying competition for prey, but were spatially separated in burrow soil. With their highly enriched 15 N/ 14 N and marine 13 C/ 12 C, larvae and protonymphs of the histiostomatid mite Myianoetus antipodus stood alone. Blue penguin burrows therefore support a diverse invertebrate fauna that incorporates terrestrial soil as well as varying proportions of the various blue penguin discards. (author). 45 refs., 1 fig., 1 tab.

  19. Pre-Migratory Movements by Juvenile Burrowing Owls in a Patchy Landscape

    Directory of Open Access Journals (Sweden)

    L. Danielle. Todd

    2007-12-01

    Full Text Available Dispersal is a fundamental aspect of population dynamics, and can have direct implications on processes such as the colonization of habitat patches. Pre-migratory movements, landscape fragmentation, and body condition have all been hypothesized as key factors influencing dispersal in birds, but little direct evidence exists to support these ideas. We used radio-telemetry and supplementary feeding to test if body condition or landscape pattern influenced pre-migratory movements of juvenile Burrowing Owls (Athene cunicularia in a fragmented landscape. We categorized grassland patches as either large (≥95 ha or small and isolated (≤58 ha and ≥1.5 km to next nearest grassland patch, and young owls were either provided supplemental food as nestlings or not. Owlets receiving supplemental food and residing in large grassland patches moved a greater maximum distance from their nest than similarly fed owlets residing in small patches (large = 1605 ± 443 m; small = 373 ± 148 m. In contrast, non-supplemented owlets from large and small patches did not differ in their maximum distance moved from the nest (large = 745 ± 307 m; small 555 ± 286 m. Only two of 32 individuals from small patches moved >800 m, whereas ten of 23 owlets from large patches moved >800 m. In addition, owlets from large patches continued to move farther and farther from their nest before migration, whereas owlets in small, isolated patches ultimately moved

  20. Effects of radiotransmitter necklaces on behaviors of adult male western burrowing owls

    Science.gov (United States)

    Chipman, E.D.; McIntyre, N.E.; Ray, J.D.; Wallace, M.C.; Boal, C.W.

    2007-01-01

    We studied the behavioral effects of necklace-style radiotransmitters on breeding male western burrowing owls (Athene cunicularia hypugaea) in 2 areas of northwestern Texas, USA, in 2004 and 2005. We tested the hypothesis that transmittered owls would spend time interacting with their necklaces and as a result spend less time in vigilance and resting activities than would nontransmittered owls. Nontransmittered owls (n = 6) spent significantly more time being vigilant (P = 0.007) than did transmittered owls (n = 3) in 2004, who spent significant amounts of time interacting with their necklaces. In 2005, behaviors of transmittered owls (n = 8) were significantly different (P < 0.001) from control individuals (n = 4), but behaviors did not vary consistently by treatment period (prenecklace vs. necklace vs. postnecklace periods). Behavioral activity budgets varied considerably among individuals. Although the owls spent a significant amount of time interacting with their necklaces, they appeared to habituate to the presence of the transmitters within a relatively short period (<1 week), and necklaces did not affect survivorship or fitness in the short-term.

  1. A new macrofaunal limit in the deep biosphere revealed by extreme burrow depths in ancient sediments.

    Science.gov (United States)

    Cobain, S L; Hodgson, D M; Peakall, J; Wignall, P B; Cobain, M R D

    2018-01-10

    Macrofauna is known to inhabit the top few 10s cm of marine sediments, with rare burrows up to two metres below the seabed. Here, we provide evidence from deep-water Permian strata for a previously unrecognised habitat up to at least 8 metres below the sediment-water interface. Infaunal organisms exploited networks of forcibly injected sand below the seabed, forming living traces and reworking sediment. This is the first record that shows sediment injections are responsible for hosting macrofaunal life metres below the contemporaneous seabed. In addition, given the widespread occurrence of thick sandy successions that accumulate in deep-water settings, macrofauna living in the deep biosphere are likely much more prevalent than considered previously. These findings should influence future sampling strategies to better constrain the depth range of infaunal animals living in modern deep-sea sands. One Sentence Summary: The living depth of infaunal macrofauna is shown to reach at least 8 metres in new habitats associated with sand injections.

  2. The relationship of blue crab abundance to winter mortality of Whooping Cranes

    Science.gov (United States)

    Pugesek, Bruce H.; Baldwin, Michael J.; Stehn, Thomas

    2013-01-01

    We sampled blue crab (Callinectes sapidus) numbers in marshes on the Aransas National Wildlife Refuge, Texas from 1998-2006, while simultaneously censusing the wintering population of Whooping Cranes (Grus americana) on the refuge and surrounding habitats. This was done to determine whether mortality of wintering Whooping Cranes was related to the availability of this food source. Yearly variation in crab numbers was high, ranging from a low of 0.1 crabs to a high of 3.4 crabs per 100-m transect section. Significant non-linear increases in both juvenile and adult mortality in relation to decreasing crab abundance was observed. Results suggest that some threshold of crab abundance exists in which Whooping Cranes have higher survival on their wintering grounds.

  3. Heavy metals in red crabs, Chaceon quinquedens, from the Gulf of Mexico.

    Science.gov (United States)

    Perry, Harriet; Isphording, Wayne; Trigg, Christine; Riedel, Ralf

    2015-12-30

    The red crab, Chaceon quinquedens, is distributed in deep waters of the Gulf of Mexico (GOM) and is most abundant in an area associated with sediment deposition from the Mississippi River. Sediment geochemistry and biological and ecological traits of red crabs favor accumulation of contaminants. Red crabs, sediment, and bottom water samples were taken from three distinct geographic locations representing areas with differing exposure to contaminant laden effluents from the Mississippi River. Inductively coupled plasma spectrophotometry and atomic absorption spectrophotometry were employed to determine levels of heavy metals in red crab muscle tissue. Ion site partitioning was used to determine metal speciation in sediments. Red crabs showed evidence of heavy metal bioaccumulation in all sample areas with high variability in contaminant levels in individual crabs for some metals. Bioavailability of metals in sediment did not always result in accumulation in muscle tissue. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Shell use and partitioning of two sympatric species of hermit crabs on a tropical mudflat

    Science.gov (United States)

    Teoh, Hong Wooi; Chong, Ving Ching

    2014-02-01

    Shell use and partitioning of two sympatric hermit crab species (Diogenes moosai and Diogenes lopochir), as determined by shell shape, size and availability, were examined from August 2009 to March 2011 in a tropical mudflat (Malaysia). Shells of 14 gastropod species were used but > 85% comprised shells of Cerithidea cingulata, Nassarius cf. olivaceus, Nassarius jacksonianus, and Thais malayensis. Shell partitioning between hermit crab species, sexes, and developmental stages was evident from occupied shells of different species, shapes, and sizes. Extreme bias in shell use pattern by male and female of both species of hermit crabs suggests that shell shape, which depends on shell species, is the major determinant of shell use. The hermit crab must however fit well into the shell so that compatibility between crab size and shell size becomes crucial. Although shell availability possibly influenced shell use and hermit crab distribution, this is not critical in a tropical setting of high gastropod diversity and abundance.

  5. Gamma rays and neutrinos from the Crab Nebula produced by pulsar accelerated nuclei

    OpenAIRE

    Bednarek, W.; Protheroe, R. J.

    1997-01-01

    We investigate the consequences of the acceleration of heavy nuclei (e.g. iron nuclei) by the Crab pulsar. Accelerated nuclei can photodisintegrate in collisions with soft photons produced in the pulsar's outer gap, injecting energetic neutrons which decay either inside or outside the Crab Nebula. The protons from neutron decay inside the nebula are trapped by the Crab Nebula magnetic field, and accumulate inside the nebula producing gamma-rays and neutrinos in collisions with the matter in t...

  6. Association of the "IUCN vulnerable "spiny rat Clyomys bishopi (Rodentia:Echimyidaewith palm trees and armadillo burrows in southeastern Brazil

    Directory of Open Access Journals (Sweden)

    Adriana A Bueno

    2004-12-01

    Full Text Available The globally vulnerable Clyomys bishopi ,a semi-fossorial and colonial rodent,is apparently limited to cerrado (savannah-like vegetationphysiognomies in São Paulo State,Brazil.The aim of the study was to verify whether the presence of C.bishopi is associated to the occurrence of palm trees (Attalea gearensis, Syagrus loefgrenii and armadillo burrows.Thirty six quadrats were placed in different physiognomies of cerrado vegetation at Itirapina Ecological Station,southeastern Brazil to survey the number of C.bishopi burrows of individuals of palm trees and burrows of armadillos.There was a strong dependence and association between the number of C.bishopi burrows and all measured variables (Contingency tables and Spearman rank correlations.It is suggested that this rodent can be found in great numbers where palm trees are abundant.The use of armadillo burrows possibly makes the movement of the rodents easier inside their own galleries.Rev.Biol. Trop. 52(4:1009-1011.Epub 2005 Jun 24.El roedor colonial Clyomys bishopi está aparentemente limitado a vegetación de semi-sabana (cerradoen el estado de São Paulo,Brasil.El objetivo de este estudio fue verificar si la presencia de C.bishopi está asociada a la individuos de las palmeras Attalea gearensis,Syagrus loefgrenii y madrigueras de armadillos.El estudio fue realizado en la Estación Ecológica de Itirapina,en el sureste de Brasil.Treinta y seis cuadrantes fueron dispuestos en diferentes fisionomías del la vegetación del cerrado para encuestar el número de madrigueras de C.bishopi, árboles individuales de palma y madrigueras de armadillos.Se calcularon tablas de contingencia y correlaciones de Sperman para evaluar, respectivamente, la dependencia y asociación entre el número de madrigueras de C.bishopi y las otras variables.Se encontró una fuerte dependencia y asociación entre el número de madrigueras de C.bishopi y todas las variables medidas.Esto sugiere que este roedor alcanza grandes

  7. Appearance and partial purification of a high molecular weight protein in crabs exposed to saxitoxin.

    Science.gov (United States)

    Barber, K G; Kitts, D D; Townsley, P M; Smith, D S

    1988-01-01

    This paper provides evidence for a protein component which appears to be involved in the seasonal resistance of small shore crabs, Hemigrapsus oregonesis and Hemigrapsus nudus to saxitoxin, a principle neurotoxin involved in paralytic shellfish poisoning (PSP). This unique protein complex was isolated and partially purified by ion exchange chromatography using DEAE-cellulose from visceral tissue extracts of resistant crabs. The complex was absent in control crabs that were sensitive to saxitoxin. In addition, the protein complex was induced in the crab after acute administration of low doses of saxitoxin. Results indicate that the protein complex is acidic in nature and has an apparent mol. wt of 145,000.

  8. Edible crabs "go west": migrations and incubation cycle of Cancer pagurus revealed by electronic tags.

    Directory of Open Access Journals (Sweden)

    Ewan Hunter

    Full Text Available Crustaceans are key components of marine ecosystems which, like other exploited marine taxa, show seasonable patterns of distribution and activity, with consequences for their availability to capture by targeted fisheries. Despite concerns over the sustainability of crab fisheries worldwide, difficulties in observing crabs' behaviour over their annual cycles, and the timings and durations of reproduction, remain poorly understood. From the release of 128 mature female edible crabs tagged with electronic data storage tags (DSTs, we demonstrate predominantly westward migration in the English Channel. Eastern Channel crabs migrated further than western Channel crabs, while crabs released outside the Channel showed little or no migration. Individual migrations were punctuated by a 7-month hiatus, when crabs remained stationary, coincident with the main period of crab spawning and egg incubation. Incubation commenced earlier in the west, from late October onwards, and brooding locations, determined using tidal geolocation, occurred throughout the species range. With an overall return rate of 34%, our results demonstrate that previous reluctance to tag crabs with relatively high-cost DSTs for fear of loss following moulting is unfounded, and that DSTs can generate precise information with regards life-history metrics that would be unachievable using other conventional means.

  9. Beyond the CRAB symptoms: a study of presenting clinical manifestations of multiple myeloma.

    Science.gov (United States)

    Talamo, Giampaolo; Farooq, Umar; Zangari, Maurizio; Liao, Jason; Dolloff, Nathan G; Loughran, Thomas P; Epner, Elliot

    2010-12-01

    Although the typical clinical manifestations of multiple myeloma (MM) are summarized by the CRAB symptoms (hypercalcemia, renal insufficiency, anemia, and bone lesions), a significant proportion of patients with MM present with a variety of other clinical manifestations. We conducted a study evaluating the presenting symptoms that led to the diagnosis of MM. We conducted a retrospective review of 170 consecutive patients with MM seen at the Penn State Hershey Cancer Institute. Among patients with symptomatic MM, 74% presented with CRAB symptoms, 20% presented with non-CRAB manifestations, and 6% had both clinical features. Ten categories of non-CRAB manifestations were found, in order of decreasing frequency: neuropathy (because of spinal cord compression, nerve root compression, or peripheral neuropathy), extramedullary involvement, hyperviscosity syndrome, concomitant amyloidosis (eg, nephrotic syndrome or cardiopathy), hemorrhage/coagulopathy, systemic symptoms (eg, fever or weight loss), primary plasma cell leukemia, infections, cryoglobulinemia, and secondary gout. Kaplan-Meier estimates of survival in patients with non-CRAB manifestations did not show a significant difference from the survival of patients presenting with CRAB symptoms. Presenting symptoms of MM may be grouped in a total of 14 categories, 4 for the CRAB and 10 for the less common non-CRAB features. Grouped together, non-CRAB manifestations do not appear to confer a negative effect on the prognosis of patients with MM.

  10. Infestation of parasitic rhizocephalan barnacles Sacculina beauforti (Cirripedia, Rhizocephala in edible mud crab, Scylla olivacea

    Directory of Open Access Journals (Sweden)

    Khor Waiho

    2017-06-01

    Full Text Available Screening of mud crab genus Scylla was conducted in four locations (Marudu Bay, Lundu, Taiping, Setiu representing Malaysia. Scylla olivacea with abnormal primary and secondary sexual characters were prevalent (approximately 42.27% of the local screened S. olivacea population in Marudu Bay, Sabah. A total of six different types of abnormalities were described. Crabs with type 1 and type 3 were immature males, type 2 and type 4 were mature males, type 5 were immature females and type 6 were mature females. The abdomen of all crabs with abnormalities were dented on both sides along the abdomen’s middle line. Abnormal crabs showed significant variation in their size, weight, abdomen width and/or gonopod or pleopod length compared to normal individuals. The mean body weight of abnormal crabs (type 1–5 were higher than normal crabs with smaller body size, while females with type 6 abnormality were always heavier than the normal counterparts at any given size. Sacculinid’s externa were observed in the abdomen of crabs with type 4 and type 6 abnormalities. The presence of embryos within the externa and subsequent molecular analysis of partial mitochondrial COI region confirmed the rhizocephalan parasite as Sacculina beauforti. Future in-depth descriptions of the life cycle and characteristics of S. beauforti are recommended as it involves a commercially important edible crab species and the effect on human health from the consumption of crabs is of crucial concern.

  11. Crab Pulsar Astrometry and Spin-Velocity Alignment

    Science.gov (United States)

    Romani, Roger W.; Ng, C.-Y.

    2009-01-01

    The proper motion of the Crab pulsar and its orientation with respect to the PWN symmetry axis is interesting for testing models of neutron star birth kicks. A number of authors have measured the Crab's motion using archival HST images. The most detailed study by Kaplan et al. (2008) compares a wide range of WFPC and ACS images to obtain an accurate proper motion measurement. However, they concluded that a kick comparison is fundamentally limited by the uncertainty in the progenitor's motion. Here we report on new HST images matched to 1994 and 1995 data frames, providing independent proper motion measurement with over 13 year time base and minimal systematic errors. The new observations also allow us to estimate the systematic errors due to CCD saturation. Our preliminary result indicates a proper motion consistent with Kaplan et al.'s finding. We discuss a model for the progenitor's motion, suggesting that the pulsar spin is much closer to alignment than previously suspected.

  12. Are crab-type supernova remnants (plerions) short-lived

    International Nuclear Information System (INIS)

    Weiler, K.W.; Panagia, N.

    1978-01-01

    Arguments are given for a possible picture of the origin, maintenance, and lifetimes of the so-called Crab-like supernova remnants. It is suggested that these objects imply the existence of at least two distinct types of supernova events. A possible connection of the remnant types with the optically defined supernovae of Type I and Type II is discussed. Accepting that a pulsar is formed in at least some supernova events, the proposal is made that a rapidly rotating, rapidly slowing pulsar is necessary to create and maintain a Crab-like supernova remnant. Finally, arguments are presented that such a supernova remnant will be relatively short lived with respect to the more common shell-type of supernova remnant, perhaps surviving only 10000-20000 yr before fading into the Galactic background. The name of plerion is proposed for these filled-center supernova remnants and observational possiblities for confirming their nature are suggested. (orig.) [de

  13. M10.3.1: LHC crab cavity specifications completed

    CERN Document Server

    Ciapala, E

    2010-01-01

    • The starting point of Sub-task 1 is to determine the full LHC system requirements for the crab cavity system. This milestone concerns completion of basic specifications for the crab cavity system. This comprises the beam requirements, the cavity impedance constraints, the operating conditions and constraints, the layout and integration constraints in LHC and very importantly machine protection issues. The specifications of the cavity itself and its ancillaries follow from these system requirements and on the technology chosen for the cavity design. • The beam requirements result from the known parameters of the LHC upgrade lattice and the expected LHC beam parameters at ultimate bunch intensity. There are boundary conditions imposed by certain beam parameters such as the bunch length and intensity and by the machine layout, mainly the available beam pipe separations at the proposed cavity positions. Requirements on RF noise and stability are tight, to avoid emittance blow-up. Machine protection issues a...

  14. North Sea ecosystem change from swimming crabs to seagulls.

    Science.gov (United States)

    Luczak, C; Beaugrand, G; Lindley, J A; Dewarumez, J-M; Dubois, P J; Kirby, R R

    2012-10-23

    A recent increase in sea temperature has established a new ecosystem dynamic regime in the North Sea. Climate-induced changes in decapods have played an important role. Here, we reveal a coincident increase in the abundance of swimming crabs and lesser black-backed gull colonies in the North Sea, both in time and in space. Swimming crabs are an important food source for lesser black-backed gulls during the breeding season. Inhabiting the land, but feeding mainly at sea, lesser black-backed gulls provide a link between marine and terrestrial ecosystems, since the bottom-up influence of allochthonous nutrient input from seabirds to coastal soils can structure the terrestrial food web. We, therefore, suggest that climate-driven changes in trophic interactions in the marine food web may also have ensuing ramifications for the coastal ecology of the North Sea.

  15. Crab Flares and Magnetic Reconnection in Pulsar Winds

    Science.gov (United States)

    Harding, Alice K.

    2012-01-01

    The striped winds of rotation-powered pulsars are ideal sites for magnetic reconnection. The magnetic fields of the wind near the current sheet outside the light cylinder alternate polarity every pulsar period and eventually encounter a termination shock. Magnetic reconnection in the wind has been proposed as a mechanism for transferring energy from electromagnetic fields to particles upstream of the shock (the "sigma" problem), but it is not clear if, where and how this occurs. Fermi and AGILE have recently observed powerful gamma-ray flares from the Crab nebula, which challenge traditional models of acceleration at the termination shock. New simulations are revealing that magnetic reconnection may be instrumental in understanding the Crab flares and in resolving the "sigma" problem in pulsar wind nebulae.

  16. Modelling the ArH+ emission from the Crab nebula

    Science.gov (United States)

    Priestley, F. D.; Barlow, M. J.; Viti, S.

    2017-12-01

    We have performed combined photoionization and photodissociation region (PDR) modelling of a Crab nebula filament subjected to the synchrotron radiation from the central pulsar wind nebula, and to a high flux of charged particles; a greatly enhanced cosmic-ray ionization rate over the standard interstellar value, ζ0, is required to account for the lack of detected [C I] emission in published Herschel SPIRE FTS observations of the Crab nebula. The observed line surface brightness ratios of the OH+ and ArH+ transitions seen in the SPIRE FTS frequency range can only be explained with both a high cosmic-ray ionization rate and a reduced ArH+ dissociative recombination rate compared to that used by previous authors, although consistent with experimental upper limits. We find that the ArH+/OH+ line strengths and the observed H2 vibration-rotation emission can be reproduced by model filaments with nH = 2 × 104 cm-3, ζ = 107ζ0 and visual extinctions within the range found for dusty globules in the Crab nebula, although far-infrared emission from [O I] and [C II] is higher than the observational constraints. Models with nH = 1900 cm-3 underpredict the H2 surface brightness, but agree with the ArH+ and OH+ surface brightnesses and predict [O I] and [C II] line ratios consistent with observations. These models predict HeH+ rotational emission above detection thresholds, but consideration of the formation time-scale suggests that the abundance of this molecule in the Crab nebula should be lower than the equilibrium values obtained in our analysis.

  17. Crab Hole Mosquito Blues—The Story

    Centers for Disease Control (CDC) Podcasts

    2011-05-12

    This podcast reports on a humorous song that takes a look at a very serious human and equine disease. Written and performed by the MARU Health Angels Band, Bill Dietz, director of the Division of Nutrition, Physical Activity and Obesity at CDC, talks about the song, "Crab Hole Mosquito Blues", and the history behind it.  Created: 5/12/2011 by National Center for Emerging Zoonotic and Infectious Diseases (NCEZID).   Date Released: 5/23/2011.

  18. The effect of age on encounters between male crab spiders

    OpenAIRE

    Helen H. Hu; Douglass H. Morse

    2004-01-01

    In males that compete aggressively for females, size and age may determine which males obtain access to these females. In the present study, we use the crab spider, Misumena vatia, a species with males that do not grow after becoming sexually mature adults, to test the hypothesis that age affects the success of males competing for access to females. M. vatia is an excellent species to test this hypothesis because it is possible to disentangle age from size, characters that typically vary toge...

  19. Feeding and decoration preferences of the epialtidae crab Acanthonyx scutiforms

    OpenAIRE

    Vasconcelos, Marcelo Augusto; Mendes, Thiago Costa; Fortes, Wagner Luiz Soares; Pereira, Renato Crespo

    2009-01-01

    Studies on the feeding preferences of marine herbivores are very important for our better understanding of the biology and the ecological role of these organisms. Members of the family Epialtidae are usually herbivores that mask themselves with pieces of seaweed and other materials to avoid predation. In order to better understand the mechanisms of food and decorating choices of the decorator crab Acanthonyx scutiformis, two multiple-choice feeding assays were performed using fresh seaweeds a...

  20. On the injection of relativistic particles into the Crab Nebula

    International Nuclear Information System (INIS)

    Shklovskij, I.S.

    1977-01-01

    It is shown that a flux of relativistic electrons from the NP 0532 pulsar magnetosphere, responsible for its synchrotron emission, cannot provide the necessary energy pumping to the Crab Nebula. A conclusion is reached that such a pumping can be effectuated by a flow of relativistic electrons leaving the NP 0532 magnetosphere at small pitch angles and giving therefore no appreciable contribution to the synchrotron emission of the pulsar. An interpretation of the Crab Nebula synchrotron spectrum is given on the assumption of secular ''softening'' of the energy spectrum of the relativistic electrons injected into the Nebula. A possibility of explanation of the observed rapid variability of some features in the central part of the Nebula by ejection of free - neutron - rich dense gas clouds from the pulsar surface during ''starquakes'' is discussed. The clouds of rather dense (nsub(e) approximately 10 7 cm -3 ) plasma, thus formed at about 10 13 cm from pulsar, will be accelerated up to relativistic velocities by the pressure of the magneto-dipole radiation of NP 0532 and will deform the magnetic field in the inner part (R 17 cm) of the Crab Nebula, that is the cause of the variability observed. In this case, favourable conditions for the acceleration of the particles in the cloud up to relativistic energies are realized; that may be an additional source of injection

  1. Differential escape from parasites by two competing introduced crabs

    Science.gov (United States)

    Blakeslee, April M.; Keogh, Carolyn L.; Byers, James E.; Kuris, Armand M.; Lafferty, Kevin D.; Torchin, Mark E.

    2009-01-01

    Although introduced species often interact with one another in their novel communities, the role of parasites in these interactions remains less clear. We examined parasite richness and prevalence in 2 shorecrab species with different invasion histories and residency times in an introduced region where their distributions overlap broadly. On the northeastern coast of the USA, the Asian shorecrab Hemigrapsus sanguineus was discovered 20 yr ago, while the European green crab Carcinus maenas has been established for over 200 yr. We used literature and field surveys to evaluate parasitism in both crabs in their native and introduced ranges. We found only 1 parasite species infecting H. sanguineus on the US East Coast compared to 6 species in its native range, while C. maenas was host to 3 parasite species on the East Coast compared to 10 in its native range. The prevalence of parasite infection was also lower for both crabs in the introduced range compared to their native ranges; however, the difference was almost twice as much for H. sanguineus as for C. maenas. There are several explanations that could contribute to C. maenas' greater parasite diversity than that of H. sanguineus on the US East Coast, including differences in susceptibility, time since introduction, manner of introduction (vector), distance from native range, taxonomic isolation, and the potential for parasite identification bias. Our study underscores not just that non-native species lose parasites upon introduction, but that they may do so differentially, with ramifications for their direct interactions and with potential community-level influences.

  2. AFSC/RACE/SAP: Detailed Crab Data From NOAA Fisheries Service 2012 Chukchi Sea Bottom Trawl Surveys

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains detailed crab data collected from the 2012 NOAA/NMFS/AFSC/RACE crab-groundfish bottom trawl survey of the Chukchi Sea. 71 survey stations were...

  3. Investigation of plutonium concentration and distribution in burrowing crayfish from the White Oak Creek floodplain

    Energy Technology Data Exchange (ETDEWEB)

    Delaney, M.S.; Dahlman, R.C.; Craig, R.B.

    1979-01-01

    The White Oak floodplain was contaminated with several radionuclides, including /sup 239/Pu, during the Manhattan Project in 1944. Plutonium distribution in the soil is nonhomogeneous. An investigation was conducted to deterine Pu accumulation in a resident animal population. Crayfish were chosen because they complete their life-cycle within the contaminated environment, they directly contact contaminated muds, and they function in a food chain of significance to man. Two major conclusions of the research were that Pu concentrations in contaminated crayfish typically exceed those of control crayfish by two orders of magnitude and that if an incident were to occur in which a standard man ingested the soft tissues of ten crayfish from the floodplain, an insignificant whole body dose would accrue over the subsequent 50 years of life. The digestive tract of contaminated crayfish contained 21 to 33% of the Pu body burden, soft tissues contained 11 to 31% of the Pu body burden, and 48 to 62% of the Pu body burden of contaminated crayfish was associated with the carapace. Therefore, at a molt a large proportion of its accumulated Pu is deposited in the environment. A supplementary laboratory investigation using /sup 237/Pu included a chronic Pu uptake study by uncontaminated crayfish. In these crayfish, from 64 to 82% of the /sup 237/Pu was associated with the body tissues. Complementary data for /sup 237/Pu associated with the carapace ranged from 18 to 37% of the distribution. An inventory of /sup 239/Pu in crayfish at two sites on the floodplain was calculated by multiplying the estimated biomass of the crayfish by their average /sup 239/Pu concentration. This evaluation of Pu associated with the crayfish population was compared to an inventory of /sup 239/Pu in the soil in which they burrow and was found to be eight orders of magnitude less.

  4. Behavioral Correlations Associated with Fear of Humans Differ between Rural and Urban Burrowing Owls

    Directory of Open Access Journals (Sweden)

    Martina Carrete

    2017-05-01

    Full Text Available Behavioral studies are fundamental to understanding how animal populations face global change. Although much research has centered upon the idea that individuals can adaptively modify their behaviors to cope with environmental changes, recent evidence supports the existence of individual differences in suites of correlated behaviors. However, little is known about how selection can change these behavioral structures in populations subject to different environmental constraints. The colonization of urban environments by birds has been related to their inter-individual variability in their fear of humans, measured as their flight initiation distance to an approaching human, such that urban life would select for fearless individuals. This behavior has been demonstrated to be heritable and highly consistent throughout the adult lifespan of burrowing owls (Athene cunicularia. Here, we experimentally assessed, in field conditions, whether urban life involves changes in other behaviors such as exploration and antipredatory response through their correlation with fear of humans. Breeding urban birds were more fearless toward humans and were quicker to explore a new food resource and defend their nests from predators than their rural counterparts. However, while fear of humans positively correlated with exploration and antipredatory response in the rural population, it only correlated with exploration in the urban one. Predator release in urban environments could relax—and even counterselect—antipredator behaviors, thus dismantling the behavioral correlation existent in natural populations. Altogether, our results suggest that rural and urban animals may differ in some behavioral aspects, may be as a consequence of the selection processes acting during the colonization of urban areas as well as the different ecological environments encountered by individuals.

  5. Investigation of plutonium concentration and distribution in burrowing crayfish from the White Oak Creek floodplain

    International Nuclear Information System (INIS)

    Delaney, M.S.; Dahlman, R.C.; Craig, R.B.

    1979-01-01

    The White Oak floodplain was contaminated with several radionuclides, including 239 Pu, during the Manhattan Project in 1944. Plutonium distribution in the soil is nonhomogeneous. An investigation was conducted to deterine Pu accumulation in a resident animal population. Crayfish were chosen because they complete their life-cycle within the contaminated environment, they directly contact contaminated muds, and they function in a food chain of significance to man. Two major conclusions of the research were that Pu concentrations in contaminated crayfish typically exceed those of control crayfish by two orders of magnitude and that if an incident were to occur in which a standard man ingested the soft tissues of ten crayfish from the floodplain, an insignificant whole body dose would accrue over the subsequent 50 years of life. The digestive tract of contaminated crayfish contained 21 to 33% of the Pu body burden, soft tissues contained 11 to 31% of the Pu body burden, and 48 to 62% of the Pu body burden of contaminated crayfish was associated with the carapace. Therefore, at a molt a large proportion of its accumulated Pu is deposited in the environment. A supplementary laboratory investigation using 237 Pu included a chronic Pu uptake study by uncontaminated crayfish. In these crayfish, from 64 to 82% of the 237 Pu was associated with the body tissues. Complementary data for 237 Pu associated with the carapace ranged from 18 to 37% of the distribution. An inventory of 239 Pu in crayfish at two sites on the floodplain was calculated by multiplying the estimated biomass of the crayfish by their average 239 Pu concentration. This evaluation of Pu associated with the crayfish population was compared to an inventory of 239 Pu in the soil in which they burrow and was found to be eight orders of magnitude less

  6. Acanthocephala Parasite (Profilicollis spp.) Loads in Correlation to Pacific Mole Crab (Emerita analoga) Size

    Science.gov (United States)

    Cheng, T.; Huang, S.; Galathe, M.; Jenkins, M.; Ramirez, A.; Crosby, L.; Barrera, J.; FitzHoward, S.

    2013-12-01

    Since 2002, San Francisco Bay students have been conducting marine ecosystem monitoring through a joint project with the Long-term Monitoring Program and Experiential Training for Students (LiMPETS), in conjunction with the Gulf of Farallones National Marine Sanctuary. Each year students collect population and demographic data on Pacific mole crabs (Emerita analoga), an indicator species that lives in the sandy beach habitat in temperate regions along the Pacific Ocean. Pacific mole crabs are filter feeding crustaceans that inhabit the intertidal swash zone and are known to be an intermediate host for parasitic ';spiny-headed' worms in the phylum Acanthocephala (Profilicollis spp.). Sampling takes place during their reproductive period, which occurs from spring to fall, and includes measuring total body length of the Pacific mole crabs and dissecting them to determine presence of Acanthocephalan parasites. We hypothesize that due to larger body mass, larger Pacific mole crabs will have a greater number of Acanthocephala parasites.We conducted several analyses using the LiMPETS long-term data. Specifically, we compared body length, crab gender, and parasite abundance from Pacific mole crabs sampled from four beaches located in the county and city of San Francisco. Our results indicated that larger Pacific mole crabs do not necessarily have more parasites, but are more likely to have at least one parasite, while female Pacific mole crabs carrying eggs, have more parasites than males or females without eggs. We also found that parasite loads per mole crab was highest in the spring. Further analysis will be conducted to determine factors affecting Pacific mole crab parasite loads. Studying Pacific mole crabs help evaluate the health of California's intertidal systems and how human activities, geologic changes, and climate changes all make huge impacts to the intertidal ecosystems.

  7. Crabbing system for an electron-ion collider

    Energy Technology Data Exchange (ETDEWEB)

    Castilla, Alejandro [Old Dominion Univ., Norfolk, VA (United States)

    2017-05-01

    As high energy and nuclear physicists continue to push further the boundaries of knowledge using colliders, there is an imperative need, not only to increase the colliding beams' energies, but also to improve the accuracy of the experiments, and to collect a large quantity of events with good statistical sensitivity. To achieve the latter, it is necessary to collect more data by increasing the rate at which these processes are being produced and detected in the machine. This rate of events depends directly on the machine's luminosity. The luminosity itself is proportional to the frequency at which the beams are being delivered, the number of particles in each beam, and inversely proportional to the cross-sectional size of the colliding beams. There are several approaches that can be considered to increase the events statistics in a collider other than increasing the luminosity, such as running the experiments for a longer time. However, this also elevates the operation expenses, while increasing the frequency at which the beams are delivered implies strong physical changes along the accelerator and the detectors. Therefore, it is preferred to increase the beam intensities and reduce the beams cross-sectional areas to achieve these higher luminosities. In the case where the goal is to push the limits, sometimes even beyond the machines design parameters, one must develop a detailed High Luminosity Scheme. Any high luminosity scheme on a modern collider considers|in one of their versions|the use of crab cavities to correct the geometrical reduction of the luminosity due to the beams crossing angle. In this dissertation, we present the design and testing of a proof-of-principle compact superconducting crab cavity, at 750 MHz, for the future electron-ion collider, currently under design at Jefferson Lab. In addition to the design and validation of the cavity prototype, we present the analysis of the first order beam dynamics and the integration of the

  8. 75 FR 49420 - Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab Fisheries; 2010 Atlantic...

    Science.gov (United States)

    2010-08-13

    .... 100513223-0289-02] RIN 0648-AY88 Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab Fisheries; 2010 Atlantic Deep-Sea Red Crab Specifications In- season Adjustment AGENCY: National Marine...-sea (DAS) allocation for the Atlantic deep- sea red crab fishery that were implemented in May 2010...

  9. 75 FR 35435 - Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab Fisheries; 2010 Atlantic...

    Science.gov (United States)

    2010-06-22

    .... 100513223-0254-01] RIN 0648-AY88 Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab Fisheries; 2010 Atlantic Deep-Sea Red Crab Specifications In- season Adjustment AGENCY: National Marine... deep-sea red crab fishery, including a target total allowable catch (TAC) and a fleet-wide days-at-sea...

  10. 76 FR 36511 - Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab; Amendment 3

    Science.gov (United States)

    2011-06-22

    ...-BA22 Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab; Amendment 3 AGENCY... the Atlantic Deep-Sea Red Crab Fishery Management Plan (FMP) (Amendment 3), incorporating a draft... current trap limit regulations state that red crab may not be harvested from gear other than a marked red...

  11. 75 FR 7435 - Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab Fisheries; 2010 Atlantic...

    Science.gov (United States)

    2010-02-19

    .... 100105009-0053-01] RIN 0648-AY51 Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab Fisheries; 2010 Atlantic Deep-Sea Red Crab Specifications AGENCY: National Marine Fisheries Service (NMFS... comments. SUMMARY: NMFS proposes 2010 specifications for the Atlantic deep-sea red crab fishery, including...

  12. 76 FR 39369 - Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab Fishery; Amendment 3

    Science.gov (United States)

    2011-07-06

    ... crab vessels may not deploy parlor traps/pots in water depths greater than 400 meters (219 fathoms... water deeper than 400 m; prohibit a limited access red crab vessel from harvesting red crab in water shallower than 400 m; and prohibit parlor traps from being deployed at water shallower than 400 m. This...

  13. Body and skull morphometric variations between two shovel-headed species of Amphisbaenia (Reptilia: Squamata with morphofunctional inferences on burrowing

    Directory of Open Access Journals (Sweden)

    Leandro dos Santos Lima Hohl

    2017-07-01

    Full Text Available Background Morphological descriptions comparing Leposternon microcephalum and L. scutigerum have been made previously. However, these taxa lack a formal quantitative morphological characterization, and comparative studies suggest that morphology and burrowing performance are be related. The excavatory movements of L. microcephalum have been described in detail. However, there is a lack of studies comparing locomotor patterns and/or performance among different amphisbaenids sharing the same skull shape. This paper presents the first study of comparative morphometric variations between two closely related amphisbaenid species, L. microcephalum and L. scutigerum, with functional inferences on fossorial locomotion efficiency. Methods Inter-specific morphometric variations were verified through statistical analyses of body and cranial measures of L. microcephalum and L. scutigerum specimens. Their burrowing activity was assessed through X-ray videofluoroscopy and then compared. The influence of morphological variation on the speed of digging was tested among Leposternon individuals. Results Leposternon microcephalum and L. scutigerum are morphometrically distinct species. The first is shorter and robust with a wider head while the other is more elongated and slim with a narrower head. They share the same excavatory movements. The animals analyzed reached relatively high speeds, but individuals with narrower skulls dug faster. A negative correlation between the speed and the width of skull was determined, but not with total length or diameter of the body. Discussion The morphometric differences between L. microcephalum and L. scutigerum are in accord with morphological variations previously described. Since these species performed the same excavation pattern, we may infer that closely related amphisbaenids with the same skull type would exhibit the same excavatory pattern. The negative correlation between head width and excavation speed is also

  14. The chemistry and mineralogy of haloed burrows in pelagic sediment at DOMES Site A: The equatorial North Pacific

    Science.gov (United States)

    Piper, D.Z.; Rude, P.D.; Monteith, S.

    1987-01-01

    The chemical and mineralogical composition of burrowed sediment, recovered in 66 box cores at latitude 9??25???N and longitude 151??15???W in the equatorial Pacific, demonstrates the important role of infauna in determining the geochemistry of pelagic sediment. Haloed burrows, approximately 3 cm across, were present in many of the cores. Within early Tertiary sediment that was covered by less than 5 cm of surface Quaternary sediment in several cores, the burrows in cross-section consist of three units: (1) a dark yellowish-brown central zone of Quaternary sediment surrounded, by (2) a pale yellowish-orange zone (the halo) of Tertiary sediment, which is surrounded by (3) a metal-oxide precipitate; the enclosing Tertiary sediment is dusky brown. Several elements - Mn, Ni, Cu, Co, Zn, Sb and Ce - have been leached from the light-colored halo, whereas Cr, Cs, Hf, Rb, Sc, Ta, Th, U, the rare earth elements exclusive of Ce, and the major oxides have not been leached. The metal-oxide zone, 1-5 mm thick, contains as much as 16% MnO2, as the mineral todorokite. The composition of the todorokite, exclusive of the admixed Tertiary sediment, resembles the composition of the metal deficit of the halo and also the composition of surface ferromanganese nodules that have been interpreted as having a predominantly diagenetic origin. Thus bioturbation contributes not only to the redistribution of metals within pelagic sediment, but also to the accretion of ferromanganese nodules on the sea floor. ?? 1987.

  15. Comparison of hydraulics and particle removal efficiencies in a mixed cell raceway and Burrows pond rearing system

    Science.gov (United States)

    Moffitt, Christine M.

    2016-01-01

    We compared the hydrodynamics of replicate experimental mixed cell and replicate standard Burrows pond rearing systems at the Dworshak National Fish Hatchery, ID, in an effort to identify methods for improved solids removal. We measured and compared the hydraulic residence time, particle removal efficiency, and measures of velocity using several tools. Computational fluid dynamics was used first to characterize hydraulics in the proposed retrofit that included removal of the traditional Burrows pond dividing wall and establishment of four counter rotating cells with appropriate drains and inlet water jets. Hydraulic residence time was subsequently established in the four full scale test tanks using measures of conductivity of a salt tracer introduced into the systems both with and without fish present. Vertical and horizontal velocities were also measured with acoustic Doppler velocimetry in transects across each of the rearing systems. Finally, we introduced ABS sinking beads that simulated fish solids then followed the kinetics of their removal via the drains to establish relative purge rates. The mixed cell raceway provided higher mean velocities and a more uniform velocity distribution than did the Burrows pond. Vectors revealed well-defined, counter-rotating cells in the mixed cell raceway, and were likely contributing factors in achieving a relatively high particle removal efficiency-88.6% versus 8.0% during the test period. We speculate retrofits of rearing ponds to mixed cell systems will improve both the rearing environments for the fish and solids removal, improving the efficiency and bio-security of fish culture. We recommend further testing in hatchery production trials to evaluate fish physiology and growth.

  16. A new marine triclad ectoparasitic on Malaysian and Indonesian horseshoe crabs (Platyhelminthes, Turbellaria, Tricladida)

    NARCIS (Netherlands)

    Sluys, Ronald

    1983-01-01

    A new species of marine triclad, Ectoplana undata n. sp., ectoparasitic on the horseshoe crab Tachypleus gigas, is described. Cocoons of triclads were found on T. gigas as well as on the horseshoe crab Carcinoscorpius rotundicauda; since from the latter species no triclads were collected, it remains

  17. Mating Success of Female Dungeness Crabs (Cancer magister) in Oregon Coastal Waters

    DEFF Research Database (Denmark)

    Dunn, Paul; Shanks, Alan

    2012-01-01

    year, and when combined with crabs that carried sperm from previous mating encounters (females store sperm), the percent of females that would have produced viable eggs was 83%. Crabs that definitely molted during the collection year showed higher mating success (95%). The largest females examined...

  18. Evolution of crabs – history and deconstruction of a prime example of convergence

    NARCIS (Netherlands)

    Scholtz, G.

    2014-01-01

    Compared with the elongate bodies of shrimps or lobsters, crabs are characterised by a compact body organisation with a depressed, short carapace and a ventrally folded pleon. The evolutionary transformation from a lobster-like crustacean towards a crab is called ‘carcinization’ and has been

  19. Dungeness crab survey for the Southwest Ocean Disposal Site off Grays Harbor, Washington, June 1990

    Energy Technology Data Exchange (ETDEWEB)

    Higgins, B.J.; Pearson, W.H. (Battelle/Marine Sciences Lab., Sequim, WA (United States))

    1991-09-01

    As part of the Grays Harbor Navigation Improvement Project, the Seattle District of the US Army Corps of Engineers has begun active use of the Southwest Ocean Disposal Site off Grays Harbor, Washington. This survey was to verify that the location of the area of high crab density observed during site selection surveys has not shifted into the Southeast Ocean Disposal Site. In June 1990, mean densities of juvenile Dungeness crab were 146 crab/ha within the disposal site and 609 crab/ha outside ad north of the disposal site. At nearshore locations outside the disposal site, juvenile crab density was 3275 crab/ha. Despite the low overall abundance, the spatial distribution of crab was such that the high crab densities in 1990 have remained outside the Southwest Ocean Disposal Site. The survey data have confirmed the appropriateness of the initial selection of the disposal site boundaries and indicated no need to move to the second monitoring tier. 8 refs., 9 figs., 2 tabs.

  20. The variable colours of the fiddler crab Uca vomeris and their relation to background and predation.

    Science.gov (United States)

    Hemmi, Jan M; Marshall, Justin; Pix, Waltraud; Vorobyev, Misha; Zeil, Jochen

    2006-10-01

    Colour changes in fiddler crabs have long been noted, but a functional interpretation is still lacking. Here we report that neighbouring populations of Uca vomeris in Australia exhibit different degrees of carapace colours, which range from dull mottled to brilliant blue and white. We determined the spectral characteristics of the mud substratum and of the carapace colours of U. vomeris and found that the mottled colours of crabs are cryptic against this background, while display colours provide strong colour contrast for both birds and crabs, but luminance contrast only for a crab visual system. We tested whether crab populations may become cryptic under the influence of bird predation by counting birds overflying or feeding on differently coloured colonies. Colonies with cryptically coloured crabs indeed experience a much higher level of bird presence, compared to colourful colonies. We show in addition that colourful crab individuals subjected to dummy bird predation do change their body colouration over a matter of days. The crabs thus appear to modify their social signalling system depending on their assessment of predation risk.

  1. Present and future distributions of horseshoe crabs under predicted climate changes

    DEFF Research Database (Denmark)

    Funch, Peter; Obst, Matthias; Quevedo, Francisco

    The habitats of South East Asian horseshoe crabs span across the shallow waters of many countries and biogeographic regions in the Indo-Pacific. Such ubiquitous presence makes it difficult to obtain an up-to-date and overall picture of the current distribution, density and wealth of horseshoe crab...

  2. A review of fiddler crabs (genus Uca Leach, 1814) in South Africa ...

    African Journals Online (AJOL)

    Fiddler crabs occur globally across tropical and subtropical coastal habitats including mangrove swamps, which are in decline worldwide. The genus has been well-studied in the Americas, Australia and Asia, whereas information on African species is scarce. This review summarises the existing literature on fiddler crabs ...

  3. Line features in the X-ray spectrum of the crab pulsar

    International Nuclear Information System (INIS)

    Hasinger, G.; Pietsch, W.; Reppin, C.; Truemper, J.; Voges, W.; Kendziorra, E.; Staubert, R.

    1982-01-01

    Beside the well-known synchrotron behaviour of the Crab pulsar, there may be another source of high energy emission due to a hot plasma. The similarities between this component and common accretion-fed X-ray binaries are the frame in which the present balloon observation of the Crab pulsar will be discussed. (orig./WL)

  4. Associations between dioxins/furans and dioxin-like PCBs in estuarine sediment and blue crab

    Science.gov (United States)

    Liebens, J.; Mohrherr, C.J.; Karouna-Renier, N. K.; Snyder, R.A.; Rao, K.R.

    2011-01-01

    The objective of the present study was to evaluate the relationships between the quantity, toxicity, and compositional profile of dioxin/furan compounds (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) in estuarine sediment and in the blue crab (Callinectes sapidus). Sediment and blue crab samples were collected in three small urban estuaries that are in relatively close proximity to each other. Results show that differences between PCDD/F and DL-PCB mass concentrations and total toxic equivalents (TEQ) toxicity in sediments of the three estuaries are reflected in those of the blue crab. TEQs are higher in the hepatopancreas of the crabs than in the sediment, but the concentration factor is inversely proportional to the TEQ in the sediments. Congener profiles in the crabs are systematically different from those in the sediments, and the difference is more pronounced for PCDD/Fs than for DL-PCBs, possibly due to differences in metabolization rates. Compared with sediment profiles, more lesser-chlorinated PCDD/Fs that have higher TEFs accumulate in crab hepatopancreas. This selective bioaccumulation of PCDD/Fs results in a TEQ augmentation in crab hepatopancreas compared with sediments. The bioaccumulation in the blue crab is also selective for PCDD/Fs over DL-PCBs. ?? 2011 Springer Science+Business Media B.V.

  5. Study with one global crab cavity at IR4 for LHC Upgrade

    CERN Document Server

    Barranco, J; Morita, A; Ralph Assmann, R; Sun, Y; Tomás, R; Weiler, T; Zimmermann, F; CERN. Geneva. BE Department

    2009-01-01

    In this note, we discuss the possible installation and impact on the beam of a single global crab cavity (CC) for both nominal LHC optics and one upgrade LHC optics (Lowbetamax). We also summarize the results on dynamic aperture tracking, luminosity, expected closed orbits, preliminary studies on collimation cleaning efficiency, and the emittance growth due to crab cavity ramping and other sources.

  6. Ex-vivo evaluation of crab shell chitosan as absorption enhancer in ...

    African Journals Online (AJOL)

    This study was aimed at evaluating crab shell chitosan as absorption enhancer in ciprofloxacin tablet formulation using the ex-vivo model. Six batches of ciprofloxacin tablets containing varying concentrations of crab shell-derived chitosan ranging from 0 to 5% w/w at 1% w/w intervals were produced. Batch CTS-0 ...

  7. A glitch in the Crab pulsar (PSR B0531+21)

    Science.gov (United States)

    Shaw, Benjamin; Lyne, Andrew; Bassa, Cees; Breton, Rene; Jordan, Christine; Keith, Michael; Mickaliger, Mitchell B.; Stappers, Benjamin; Weltevrede, Patrick

    2018-05-01

    We have detected a glitch in the Crab pulsar, B0531+21, on 2018-04-29. The Crab pulsar is regularly monitored with the 42-ft and Lovell telescopes at the Jodrell Bank Observatory as part of the pulsar timing programme.

  8. Giant robber crabs monitored from space: GPS-based telemetric studies on Christmas Island (Indian Ocean).

    Science.gov (United States)

    Krieger, Jakob; Grandy, Ronald; Drew, Michelle M; Erland, Susanne; Stensmyr, Marcus C; Harzsch, Steffen; Hansson, Bill S

    2012-01-01

    We investigated the navigational capabilities of the world's largest land-living arthropod, the giant robber crab Birgus latro (Anomura, Coenobitidae); this crab reaches 4 kg in weight and can reach an age of up to 60 years. Populations are distributed over small Indo-Pacific islands of the tropics, including Christmas Island (Indian Ocean). Although this species has served as a crustacean model to explore anatomical, physiological, and ecological aspects of terrestrial adaptations, few behavioral analyses of it exist. We used a GPS-based telemetric system to analyze movements of freely roaming robber crabs, the first large-scale study of any arthropod using GPS technology to monitor behavior. Although female robber crabs are known to migrate to the coast for breeding, no such observations have been recorded for male animals. In total, we equipped 55 male robber crabs with GPS tags, successfully recording more than 1,500 crab days of activity, and followed some individual animals for as long as three months. Besides site fidelity with short-distance excursions, our data reveal long-distance movements (several kilometers) between the coast and the inland rainforest. These movements are likely related to mating, saltwater drinking and foraging. The tracking patterns indicate that crabs form route memories. Furthermore, translocation experiments show that robber crabs are capable of homing over large distances. We discuss if the search behavior induced in these experiments suggests path integration as another important navigation strategy.

  9. Urban pollution of sediments: Impact on the physiology and burrowing activity of tubificid worms and consequences on biogeochemical processes

    Energy Technology Data Exchange (ETDEWEB)

    Pigneret, M., E-mail: mathilde.pigneret@univ-lyon1.fr [LEHNA, UMR CNRS 5023, Ecologie des Hydrosystèmes Naturels et Anthropisés, Université de Lyon, Université Lyon 1, ENTPE, 6 rue Raphael Dubois, 69622 Villeurbanne (France); Mermillod-Blondin, F.; Volatier, L.; Romestaing, C. [LEHNA, UMR CNRS 5023, Ecologie des Hydrosystèmes Naturels et Anthropisés, Université de Lyon, Université Lyon 1, ENTPE, 6 rue Raphael Dubois, 69622 Villeurbanne (France); Maire, E.; Adrien, J. [MATEIS, UMR CNRS 5510, INSA de Lyon, 25 avenue Jean Capelle, 69621 Villeurbanne (France); Guillard, L.; Roussel, D.; Hervant, F. [LEHNA, UMR CNRS 5023, Ecologie des Hydrosystèmes Naturels et Anthropisés, Université de Lyon, Université Lyon 1, ENTPE, 6 rue Raphael Dubois, 69622 Villeurbanne (France)

    2016-10-15

    In urban areas, infiltration basins are designed to manage stormwater runoff from impervious surfaces and allow the settling of associated pollutants. The sedimentary layer deposited at the surface of these structures is highly organic and multicontaminated (mainly heavy metals and hydrocarbons). Only few aquatic species are able to maintain permanent populations in such an extreme environment, including the oligochaete Limnodrilus hoffmeisteri. Nevertheless, the impact of urban pollutants on these organisms and the resulting influence on infiltration basin functioning remain poorly studied. Thus, the aim of this study was to determine how polluted sediments could impact the survival, the physiology and the bioturbation activity of L. hoffmeisteri and thereby modify biogeochemical processes occurring at the water-sediment interface. To this end, we conducted laboratory incubations of worms, in polluted sediments from infiltration basins or slightly polluted sediments from a stream. Analyses were performed to evaluate physiological state and burrowing activity (X-ray micro-tomography) of worms and their influences on biogeochemical processes (nutrient fluxes, CO{sub 2} and CH{sub 4} degassing rates) during 30-day long experiments. Our results showed that worms exhibited physiological responses to cope with high pollution levels, including a strong ability to withstand the oxidative stress linked to contamination with heavy metals. We also showed that the presence of urban pollutants significantly increased the burrowing activity of L. hoffmeisteri, demonstrating the sensitivity and the relevance of such a behavioural response as biomarker of sediment toxicity. In addition, we showed that X-ray micro-tomography was an adequate technique for accurate and non-invasive three-dimensional investigations of biogenic structures formed by bioturbators. The presence of worms induced stimulations of nutrient fluxes and organic matter recycling (between + 100% and 200% of CO

  10. DID THE CRAB PULSAR UNDERGO A SMALL GLITCH IN 2006 LATE MARCH/EARLY APRIL?

    Energy Technology Data Exchange (ETDEWEB)

    Vivekanand, M., E-mail: viv.maddali@gmail.com [No. 24, NTI Layout 1st Stage, 3rd Main, 1st Cross, Nagasettyhalli, Bangalore 560094 (India)

    2016-08-01

    On 2006 August 23 the Crab Pulsar underwent a glitch, which was reported by the Jodrell Bank and the Xinjiang radio observatories. Neither data are available to the public. However, the Jodrell group publishes monthly arrival times of the Crab Pulsar pulse (their actual observations are done daily), and using these, it is shown that about 5 months earlier the Crab Pulsar probably underwent a small glitch, which has not been reported before. Neither observatory discusses the detailed analysis of data from 2006 March to August; either they may not have detected this small glitch, or they may have attributed it to timing noise in the Crab Pulsar. The above result is verified using X-ray data from RXTE . If this is indeed true, this is probably the smallest glitch observed in the Crab Pulsar so far, whose implications are discussed. This work addresses the confusion possible between small-magnitude glitches and timing noise in pulsars.

  11. Pharmacokinetics of cefovecin (Convenia) in white bamboo sharks (Chiloscyllium plagiosum) and Atlantic horseshoe crabs (Limulus polyphemus).

    Science.gov (United States)

    Steeil, James C; Schumacher, Juergen; George, Robert H; Bulman, Frank; Baine, Katherine; Cox, Sherry

    2014-06-01

    Cefovecin was administered to six healthy adult white bamboo sharks (Chiloscyllium plagiosum) and six healthy adult Atlantic horseshoe crabs (Limulus polyphemus) to determine its pharmacokinetics in these species. A single dose of cefovecin at 8 mg/kg was administered subcutaneously in the epaxial region of the bamboo sharks and in the proximal articulation of the lateral leg of the horseshoe crabs. Blood and hemolymph samples were collected at various time points from bamboo sharks and Atlantic horseshoe crabs. High performance liquid chromatography was performed to determine plasma levels of cefovecin. The terminal halflife of cefovecin in Atlantic horseshoe crabs was 37.70 +/- 9.04 hr and in white bamboo sharks was 2.02 +/- 4.62 hr. Cefovecin concentrations were detected for 4 days in white bamboo sharks and for 14 days in Atlantic horseshoe crabs. No adverse effects associated with cefovecin administration were seen in either species.

  12. AFSC/RACE/SAP/Long: Data from: Habitat, predation, growth, and coexistence: Could interactions between juvenile red and blue king crabs limit blue king crab productivity?

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set is from a series of laboratory experiments examining the interactions between red and blue king crabs and habitat. We examined how density and predator...

  13. Trait aggressiveness does not predict social dominance of rats in the Visible Burrow System.

    Science.gov (United States)

    Buwalda, Bauke; Koolhaas, Jaap M; de Boer, Sietse F

    2017-09-01

    Hierarchical social status greatly influences health and well-being in mammals, including humans. The social rank of an individual is established during competitive encounters with conspecifics. Intuitively, therefore, social dominance and aggressiveness may seem intimately linked. Yet, whether an aggressive personality trait may predispose individuals to a particular rank in a social colony setting remains largely unclear. Here we tested the hypothesis that high trait aggressiveness in Wildtype Groningen (WTG) rats, as assessed in a classic resident-intruder offensive aggression paradigm predicts social dominance in a mixed-sex colony housing using the Visible Burrow System (VBS). We also hypothesized that hierarchical steepness, as reflected in the number and intensity of the social conflicts, positively correlates with the average level of trait aggressiveness of the male subjects in the VBS. Clear and stable hierarchical ranking was formed within a few days in VBS colonies as indicated and reflected by a rapid loss of body weight in subordinates which stabilized after 2-3days. Social conflicts, that occurred mainly during these first few days, also resulted in bite wounds in predominantly subordinate males. Data clearly showed that trait aggressiveness does not predict dominance status. The most aggressive male in a mixed sex group of conspecifics living in a closed VBS environment does not always become the dominant male. In addition, data did not convincingly indicate that in colonies with only highly aggressive males, agonistic interactions were more intense. Number of bite wounds and body weight loss did not positively correlate with trait-aggressiveness of subordinates. In this study, rats from this wild-derived rat strain behave differently from Long-Evans laboratory rats that have been studied up till now in many experiments using the VBS. Strain dependent differences in the capacity to display appropriate social behavior fitting an adaptive strategy to

  14. Effects of ocean acidification on juvenile red king crab (Paralithodes camtschaticus and Tanner crab (Chionoecetes bairdi growth, condition, calcification, and survival.

    Directory of Open Access Journals (Sweden)

    William Christopher Long

    Full Text Available Ocean acidification, a decrease in the pH in marine waters associated with rising atmospheric CO2 levels, is a serious threat to marine ecosystems. In this paper, we determine the effects of long-term exposure to near-future levels of ocean acidification on the growth, condition, calcification, and survival of juvenile red king crabs, Paralithodes camtschaticus, and Tanner crabs, Chionoecetes bairdi. Juveniles were reared in individual containers for nearly 200 days in flowing control (pH 8.0, pH 7.8, and pH 7.5 seawater at ambient temperatures (range 4.4-11.9 °C. In both species, survival decreased with pH, with 100% mortality of red king crabs occurring after 95 days in pH 7.5 water. Though the morphology of neither species was affected by acidification, both species grew slower in acidified water. At the end of the experiment, calcium concentration was measured in each crab and the dry mass and condition index of each crab were determined. Ocean acidification did not affect the calcium content of red king crab but did decrease the condition index, while it had the opposite effect on Tanner crabs, decreasing calcium content but leaving the condition index unchanged. This suggests that red king crab may be able to maintain calcification rates, but at a high energetic cost. The decrease in survival and growth of each species is likely to have a serious negative effect on their populations in the absence of evolutionary adaptation or acclimatization over the coming decades.

  15. Identification of mud crab reovirus VP12 and its interaction with the voltage-dependent anion-selective channel protein of mud crab Scylla paramamosain.

    Science.gov (United States)

    Xu, Hai-Dong; Su, Hong-Jun; Zou, Wei-Bin; Liu, Shan-Shan; Yan, Wen-Rui; Wang, Qian-Qian; Yuan, Li-Li; Chan, Siuming Francis; Yu, Xiao-Qiang; He, Jian-Guo; Weng, Shao-Ping

    2015-05-01

    Mud crab reovirus (MCRV) is the causative agent of a severe disease in cultured mud crab (Scylla paramamosain), which has caused huge economic losses in China. MCRV is a double-stranded RNA virus with 12 genomic segments. In this paper, SDS-PAGE, mass spectrometry and Western blot analyses revealed that the VP12 protein encoded by S12 gene is a structural protein of MCRV. Immune electron microscopy assay indicated that MCRV VP12 is a component of MCRV outer shell capsid. Yeast two hybrid cDNA library of mud crab was constructed and mud crab voltage-dependent anion-selective channel (mcVDAC) was obtained by MCRV VP12 screening. The full length of mcVDAC was 1180 bp with an open reading frame (ORF) of 849 bp encoding a 282 amino acid protein. The mcVDAC had a constitutive expression pattern in different tissues of mud crab. The interaction between MCRV VP12 and mcVDAC was determined by co-immunoprecipitation assay. The results of this study have provided an insight on the mechanisms of MCRV infection and the interactions between the virus and mud crab. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Using the horseshoe crab, Limulus Polyphemus, in vision research.

    Science.gov (United States)

    Liu, Jiahui S; Passaglia, Christopher L

    2009-07-03

    The American horseshoe crab, Limulus Polyphemus is one of the oldest creatures on earth, and the animal continues to play an indispensable role in biomedical research. Not only does their blood contain special cells that scientists use to detect bacteriotoxins in our medicines, but their eyes also contain a neural network that has provided much insight about physiological processes operating in our visual system, such as light adaptation and lateral inhibition. The horseshoe crab remains an attractive model for vision research because the animal is large and hardy for an invertebrate, its retinal neurons are big and easily accessible, its visual system is compact and extensively studied, and its visual behavior is well defined. Moreover, the structure and function of the eyes are modulated on a daily basis by a circadian clock in the animal s brain. In short, the visual system of horseshoe crabs is simple enough to be understood yet complex enough to be interesting. In this video we present three electrophysiological paradigms for investigating the neural basis of vision that can be performed in vivo with Limulus. They are electroretinogram recording, optic nerve recording, and intraretinal recording. Electroretinogram (ERG) recordings measure with a surface electrode the summed electrical response of all cells in the eye to a flash of light. They can be used to monitor the overall sensitivity of the eye for prolong periods of time. Optic nerve recordings measure the spiking activity of single nerve fibers with an extracellular microsuction electrode. They can be used to study visual messages conveyed from the eye to the brain as well as circadian-clock messages fed back from the brain to the eye. Intraretinal recordings measure with an intracellular microelectrode the voltage fluctuations induced by light in individual cells of the eye. They can be used to elucidate cellular mechanisms of retinal processing.

  17. Ineffective crypsis in a crab spider: a prey community perspective.

    Science.gov (United States)

    Brechbühl, Rolf; Casas, Jérôme; Bacher, Sven

    2010-03-07

    Cryptic coloration is assumed to be beneficial to predators because of an increased encounter rate with unwary prey. This hypothesis is, however, very rarely, if ever, studied in the field. The aim of this study was to quantify the encounter rate and capture success of an ambush predator, in the field, as a function of its level of colour-matching with the background. We used the crab spider Misumena vatia, which varies its body colour and can thereby match the colour of the flower it hunts upon. We carried out a manipulative field experiment using a complete factorial design resulting in six different colour combinations of crab spiders and flowers differing in their degree of colour-matching. A rich and diverse set of naturally occurring insects visited the flowers while we continuously video-recorded the spider's foraging activity. This enabled us to test the crypsis, the spider avoidance and the flower visitor attraction hypotheses, all three supported by previous studies. Flower visitors of different groups either avoided crab spiders independent of colour-matching, such as solitary bees and syrphid flies, or ignored them, such as bumble-bees and honeybees. Moreover, colour-matched spiders did not have a higher encounter rate and capture success compared to the visually apparent ones. Thus, our results support the spider avoidance hypothesis, reject the two other hypotheses and uncovered a fourth behaviour: indifference to predators. Because flower visitors reacted differently, a community approach is mandatory in order to understand the function of background colour-matching in generalist predators. We discuss our results in relation to the size and sociality of the prey and in relation to the functional significance of colour change in this predator.

  18. Comparison of burrowing and stimuli-evoked pain behaviors as end-points in rat models of inflammatory pain and peripheral neuropathic pain

    Directory of Open Access Journals (Sweden)

    Arjun eMuralidharan

    2016-05-01

    Full Text Available Establishment and validation of ethologically-relevant, non-evoked behavioral end-points as surrogate measures of spontaneous pain in rodent pain models has been proposed as a means to improve preclinical to clinical research translation in the pain field. Here, we compared the utility of burrowing behavior with hypersensitivity to applied mechanical stimuli for pain assessment in rat models of chronic inflammatory and peripheral neuropathic pain. Briefly, groups of male Sprague-Dawley rats were habituated to the burrowing environment and trained over a 5-day period. Rats that burrowed ≤450g of gravel on any two days of the individual training phase were excluded from the study. The remaining rats received either a unilateral intraplantar injection of Freund’s complete adjuvant (FCA or saline, or underwent unilateral chronic constriction injury (CCI of the sciatic nerve- or sham-surgery. Baseline burrowing behavior and evoked pain behaviors were assessed prior to model induction, and twice-weekly until study completion on day 14. For FCA- and CCI-rats, but not the corresponding groups of sham-rats, evoked mechanical hypersensitivity developed in a temporal manner in the ipsilateral hindpaws. Although burrowing behavior also decreased in a temporal manner for both FCA- and CCI-rats, there was considerable inter-animal variability. By contrast, mechanical hyperalgesia and mechanical allodynia in the ipsilateral hindpaws of FCA- and CCI-rats respectively, exhibited minimal inter-animal variability. Our data collectively show that burrowing behavior is altered in rodent models of chronic inflammatory pain and peripheral neuropathic pain. However, large group sizes are needed to ensure studies are adequately powered due to considerable inter-animal variability.

  19. Effect of Gamma Radiation on Quality of Imitation Crab Meat

    International Nuclear Information System (INIS)

    Charoen, Saovapong; Sajjabut, Surasak

    2007-08-01

    Full text: Irradiation at 0.5, 1.0 and 1.5 kGy of some commercial imitation crab meats with non-vacuum packaging reduced the total viable count by 1-2 log cycles, while coliform and Staphylococcus aureus were eliminated by 1.5 kGy gamma radiation. Although TBA number of 1 and 1.5 kGy irradiated samples increased significantly, but the sensory evaluation did not show any significant differences compared with the controls. Radiation dosage of 1.5 kGy appeared to be sufficient for improving bacterial quality and eliminating coliform and Staphylococcus aureus

  20. Ineffective crypsis in a crab spider: a prey community perspective

    OpenAIRE

    Brechbühl, Rolf; Casas, Jérôme; Bacher, Sven

    2009-01-01

    Cryptic coloration is assumed to be beneficial to predators because of an increased encounter rate with unwary prey. This hypothesis is, however, very rarely, if ever, studied in the field. The aim of this study was to quantify the encounter rate and capture success of an ambush predator, in the field, as a function of its level of colour-matching with the background. We used the crab spider Misumena vatia, which varies its body colour and can thereby match the colour of the flower it hunts u...

  1. Cuticular proteins from the horseshoe crab, Limulus polyphemus

    DEFF Research Database (Denmark)

    Ditzel, Nicholas; Andersen, Svend Olav; Højrup, Peter

    2003-01-01

    Proteins were purified from the carapace cuticle of a juvenile horseshoe crab, Limulus polyphemus, and several of them were characterized by amino acid sequence determination. The proteins are small (7-16 kDa) and their isoelectric points range from 6.5 to 9.2. They have high contents of tyrosine......, ranging from 13.5 to 35.4%. Some of the proteins show sequence similarity to cuticular proteins from other arthropod groups, with the most pronounced similarity to proteins from the cuticle of the spider Araneus diadematus. Two proteins show sequence similarity to a hexamerin storage protein from Blaberus...

  2. Status of the population structure of the mangrove crab Ucides cordatus (Decapoda: Ocypodidae on the Piraquê-açu River estuary, Espírito Santo, Brazil

    Directory of Open Access Journals (Sweden)

    Rita de Cássia Conti

    2010-06-01

    Full Text Available The land crab Ucides cordatus is a keystone species of neotropical mangrove forests and an important resource of the artisanal fisheries. The spatial and temporal distribution of U. cordatus in the mangrove area of the Piraquê-açu river estuary was determined following a longitudinal estuarine salinity gradient (lower, middle, upper estuary and along the vertical intertidal gradient. The numbers of open and closed burrows were counted monthly on fixed transects, the inhabiting crabs were caught, sexed and the carapace width measured, during 1 year. The mean crab density was 2.5 ind.m-². The highest crab density (3.9 ind.m-², linked to high numbers of juvenile crabs, was found on the upper estuary and correlated with lower salinities. High intertidal levels had higher crab densities than lower intertidal levels, except in the upper estuary. Males were smaller than females; the mean carapace width of the population was 4.89 cm, below the minimum legal harvesting size (6 cm. The predominance of females over males at some sites (especially close to villages brought out the advanced level of overfishing of this U. cordatus population and highlights the urgent need of management actions.O caranguejo Ucides cordatus é uma espécie chave nos manguezais da região neotropical e um importante recurso pesqueiro para populações tradicionais. A distribuição espacial e temporal de U. cordatus no manguezal do Rio Piraquê-açu foi estudada ao longo de um gradiente de salinidade, no estuário inferior, médio e superior na faixa entre-marés. Mensalmente durante um ano. O número de tocas abertas e fechadas ao longo de transectos fixos, foi contado mensalmente, ao longo de um ano, e os caranguejos capturados foram sexados e medidos quanto à largura da carapaça, sendo posteriormente liberados. A densidade média de caranguejos foi de 2,5 ind.m-². A maior densidade (3,9 ind.m-², juntamente com o maior número de jovens, foi encontrada na parte

  3. Inactivation of Paragonimus westermani metacercariae in soy sauce-marinated and frozen freshwater crabs.

    Science.gov (United States)

    Kim, Tae Im; Oh, Se-Ra; Dai, Fuhong; Yang, Hyun-Jong; Ha, Sang-Do; Hong, Sung-Jong

    2017-03-01

    Soy sauce-marinated freshwater crabs (Eriocheir japonicus) are a source of human paragonimiasis. The viability of Paragonimus westermani metacercariae (PwMc) in marinated crabs was investigated in an experimental setting. The PwMc collected from freshwater crayfish were inoculated into freshwater crabs, which were then frozen or marinated in soy sauce. All PwMc in the freshwater crabs were inactivated after freezing for 48 h at -20 °C and after freezing for 12 h at -40 °C. After marinating for 32 days, the survival rate of PwMc in 5% NaCl soy sauce was 50%, in 7.5% NaCl soy sauce it was 33.3%, and in 10.0% NaCl soy sauce it was 31.3%. When marinated for 64 days, all PwMc were inactivated in all experimental groups. These results revealed that freezing and soy sauce marination were detrimental to the survival of PwMc in freshwater crabs. Specifically, freezing crabs for more than 48 h or soaking them in soy sauce containing at least 5.0% NaCl for 64 days can inactivate PwMc. These results can inform the production of the traditional Korean soy sauce-marinated freshwater crabs known as gejang.

  4. Intraguild predation by shore crabs affects mortality, behavior, growth, and densities of California horn snails

    Science.gov (United States)

    Lorda, J.; Hechinger, R.F.; Cooper, S. D.; Kuris, A. M.; Lafferty, Kevin D.

    2016-01-01

    The California horn snail, Cerithideopsis californica, and the shore crabs, Pachygrapsus crassipesand Hemigrapsus oregonensis, compete for epibenthic microalgae, but the crabs also eat snails. Such intraguild predation is common in nature, despite models predicting instability. Using a series of manipulations and field surveys, we examined intraguild predation from several angles, including the effects of stage-dependent predation along with direct consumptive and nonconsumptive predator effects on intraguild prey. In the laboratory, we found that crabs fed on macroalgae, snail eggs, and snails, and the size of consumed snails increased with predator crab size. In field experiments, snails grew less in the presence of crabs partially because snails behaved differently and were buried in the sediment (nonconsumptive effects). Consistent with these results, crab and snail abundances were negatively correlated in three field surveys conducted at three different spatial scales in estuaries of California, Baja California, and Baja California Sur: (1) among 61 sites spanning multiple habitat types in three estuaries, (2) among the habitats of 13 estuaries, and (3) among 34 tidal creek sites in one estuary. These results indicate that shore crabs are intraguild predators on California horn snails that affect snail populations via predation and by influencing snail behavior and performance.

  5. Summary of CARE-HHH Mini-Workshop on LHC Crab Cavity Validation, 21 August 2008

    CERN Document Server

    Calaga, R; Garoby, R; Linnecar, T; Tomás, R; Zimmermann, F; CERN. Geneva. BE Department

    2008-01-01

    A global LHC crab-cavity collaboration is rapidly advancing the R&D of a complete crab cavity cryomodule and performing the associated beam dynamics simulations compatible with a prototype test in the phase 0/I upgrade with the aim of establishing a full crab crossing scheme for the phase II upgrade of the LHC. A one day CARE-HHH mini-workshop was held on August 21, 2008 at CERN to discuss crab crossing in the LHC phase 0/I & II upgrades and this reports summarizes the activities of the four sessions that took place during the workshop. The goals of this crab-cavity workshop were fourfold: (1) to discuss prospects of crab cavities in LHC upgrades (2) to review the status of the cryomodule development and beam dynamics, (3) to establish validity requirements for LHC crab cavities which need to be demonstrated prior to their installation into the LHC, and (4) to provide guidance & coordination for the global collaborators.

  6. POSSIBILITIES OF CULTURING BIG SEA CRABS (LOBSTERS, SPINY LOBSTERS

    Directory of Open Access Journals (Sweden)

    Ivančica Strunjak-Perović

    1999-09-01

    Full Text Available By the end of the 19 th century an experimental work on culturing big sea crabs began in Europe and North America. Great demand for their flesh as well as their high price urged many institutions to explore the possibilities of a commercial production in varios parts of the world. Lobsters (Homarus sp. were mainly used for experimenting, so that the most data available refer to them. Because of the complicated larva stage spiny lobster culturing is mainly being carried out in experimental circumstances. Despite the promissing results this aquacultural activity faces many problems (long time until they achieve a commercial size, loss of eggs due to stress sensitivity during the process of moulting, canibalism. In order to minimize these problems various researches are being carried out, like temperature influence, influence of light, way of feeding, hormonal regulation of moulting frequency. Although both lobster and spiny lobsters live in the Adriatic Sea, there are no data on their culturing in our contry. Concernig conditions in our sea there are realistic possibilities for crabs production development. In this way this delicacy would be more affordable to broader population and could be a highly rated export product.

  7. Larval biology of the crab Rhithropanopeus harrisii (Gould): a synthesis.

    Science.gov (United States)

    Forward, Richard B

    2009-06-01

    This synthesis reviews the physiological ecology and behavior of larvae of the benthic crab Rhithropanopeus harrisii, which occurs in low-salinity areas of estuaries. Larvae are released rhythmically around the time of high tide in tidal estuaries and in the 2-h interval after sunset in nontidal estuaries. As in most subtidal crustaceans, the timing of larval release is controlled by the developing embryos, which release peptide pheromones that stimulate larval release behavior by the female to synchronize the time of egg hatching. Larvae pass through four zoeal stages and a postlarval or megalopal stage that are planktonic before metamorphosis. They are retained near the adult population by means of an endogenous tidal rhythm in vertical migration. Larvae have several safeguards against predation: they undergo nocturnal diel vertical migration (DVM) and have a shadow response to avoid encountering predators, and they bear long spines as a deterrent. Photoresponses during DVM and the shadow response are enhanced by exposure to chemical cues from the mucus of predator fishes and ctenophores. The primary visual pigment has a spectral sensitivity maximum at about 500 nm, which is typical for zooplankton and matches the ambient spectrum at twilight. Larvae can detect vertical gradients in temperature, salinity, and hydrostatic pressure, which are used for depth regulation and avoidance of adverse environmental conditions. Characteristics that are related to the larval habitat and are common to other crab larval species are considered.

  8. Spectral Flattening at Low Frequencies in Crab Giant Pulses

    Science.gov (United States)

    Meyers, B. W.; Tremblay, S. E.; Bhat, N. D. R.; Shannon, R. M.; Kirsten, F.; Sokolowski, M.; Tingay, S. J.; Oronsaye, S. I.; Ord, S. M.

    2017-12-01

    We report on simultaneous wideband observations of Crab giant pulses with the Parkes radio telescope and the Murchison Widefield Array (MWA). The observations were conducted simultaneously at 732 and 3100 MHz with Parkes and at 120.96, 165.76, and 210.56 MHz with the MWA. Flux density calibration of the MWA data was accomplished using a novel technique based on tied-array beam simulations. We detected between 90 and 648 giant pulses in the 120.96-210.56 MHz MWA subbands above a 5.5σ threshold, while in the Parkes subbands we detected 6344 and 231 giant pulses above a threshold of 6σ at 732 and 3100 MHz, respectively. We show, for the first time over a wide frequency range, that the average spectrum of Crab giant pulses exhibits a significant flattening at low frequencies. The spectral index, α, for giant pulses evolves from a steep, narrow distribution with a mean α =-2.6 and width {σ }α =0.5 between 732 and 3100 MHz to a wide, flat distribution of spectral indices with a mean α =-0.7 and width {σ }α =1.4 between 120.96 and 165.76 MHz. We also comment on the plausibility of giant pulse models for fast radio bursts based on this spectral information.

  9. Featured Image: A Detailed Look at the Crab Nebula

    Science.gov (United States)

    Kohler, Susanna

    2017-07-01

    Planning on watching fireworks tomorrow? Heres an astronomical firework to help you start the celebrations! A new study has stunningly detailed the Crab Nebula (click for a closer look), a nebula 6,500 light-years away thought to have been formedby a supernova explosion and the subsequent ultrarelativistic wind emitted by the pulsar at its heart. Led by Gloria Dubner (University of Buenos Aires), the authors of this study obtained new observations of the Crab Nebula from five different telescopes. They compiled these observations to compare the details of the nebulas structure across different wavelengths, which allowedthem to learnabout the sources of various features within the nebula. In the images above, thetop left shows the 3 GHz data from the Very Large Array (radio). Moving clockise, the radio data (shown in red) is composited with: infrared data from Spitzer Space Telescope, optical continuum from Hubble Space Telescope, 500-nm optical datafrom Hubble, and ultraviolet data from XMM-Newton. The final two images are of the nebula center, and they are composites of the radio imagewith X-ray data from Chandra and near-infrared data from Hubble. To read more about what Dubner and collaborators learned (and to see more spectacular images!), check out the paper below.CitationG. Dubner et al 2017 ApJ 840 82. doi:10.3847/1538-4357/aa6983

  10. Biomaterial compounds and bioactivity of horseshoe crab Carsinoscorpius rotundicauda biomass harvested from the Madura Strait

    Science.gov (United States)

    Asih, Eka Nurrahema Ning; Kawaroe, Mujizat; Bengen, Dietriech G.

    2018-03-01

    Carsinoscorpius rotundicauda or horseshoe crab biomass has great potential in pharmaceutical aspects, one of them as an antibacterial substance. Information related to the benefits of Carsinoscorpius rotundicauda biomass such as meat and blood is essential because in fact, this species is considered a pest by fishermen, a low market value and has no legal protection in Indonesia. The purpose of this study was to determine the content of biomaterial compounds of meat and bioactivity of Carsinoscorpius rotundicauda plasma on bacterial inhibition from three different stations harvested from the waters in Madura Strait. The observation of the utilization of the potential from horseshoe crab biomass ie meat and plasma was performed by measuring the content of biomaterial compound in horseshoe crab meat by HPLC method and zone of inhibition test for gram-positive and gram-negative bacteria in horseshoe crab plasma. Analysis of the relationship between the two parameters used the Principal Component Analysis. The highest content of biomaterial compounds of monoterpenoid and zoosterol is found in horseshoe crab from Bangkalan waters, namely monoterpenoid (18.33 ppm) and zoosterol (22.67 ppm), while the smallest compound content obtained in horseshoe crab from Probolinggo waters, namely monoterpenoid (13.67) ppm and zoosterol (17.33 ppm). The bioactivity of Dark Blue Plasma (BDP) and Light Blue Plasma (LBP) samples of horseshoe crab obtained around the Madura Strait has the ability to inhibit gram-positive bacteria higher than gram-negative bacteria. The total average of DBP plasma inhibitory power on Staphylococcus aureus was 10.00 mm and 10.07 mm on Bacillus, while that in LBP sample, Staphylococcus aureus was 9.11 mm and Bacillus was 9.67 mm. The high biomaterial compound content of horseshoe crab is in line with the ability of horseshoe crab plasma to inhibit Bacillus and Staphylococcus aureus.

  11. Conservation status of the American horseshoe crab, (Limulus polyphemus): A regional assessment

    Science.gov (United States)

    Smith, David R.; Brockmann, H. Jane; Beekey, Mark A.; King, Timothy L.; Millard, Michael J.; Zaldívar-Rae, Jaime

    2017-01-01

    Horseshoe crabs have persisted for more than 200 million years, and fossil forms date to 450 million years ago. The American horseshoe crab (Limulus polyphemus), one of four extant horseshoe crab species, is found along the Atlantic coastline of North America ranging from Alabama to Maine, USA with another distinct population on the coasts of Campeche, Yucatán and Quintana Roo in the Yucatán Peninsula, México. Although the American horseshoe crab tolerates broad environmental conditions, exploitation and habitat loss threaten the species. We assessed the conservation status of the American horseshoe crab by comprehensively reviewing available scientific information on its range, life history, genetic structure, population trends and analyses, major threats, and conservation. We structured the status assessment by six genetically-informed regions and accounted for sub-regional differences in environmental conditions, threats, and management. The transnational regions are Gulf of Maine (USA), Mid-Atlantic (USA), Southeast (USA), Florida Atlantic (USA), Northeast Gulf of México (USA), and Yucatán Peninsula (México). Our conclusion is that the American horseshoe crab species is vulnerable to local extirpation and that the degree and extent of risk vary among and within the regions. The risk is elevated in the Gulf of Maine region due to limited and fragmented habitat. The populations of horseshoe crabs in the Mid-Atlantic region are stable in the Delaware Bay area, and regulatory controls are in place, but the risk is elevated in the New England area as evidenced by continuing declines understood to be caused by over-harvest. The populations of horseshoe crabs in the Southeast region are stable or increasing. The populations of horseshoe crabs in the Florida Atlantic region show mixed trends among areas, and continuing population reductions at the embayment level have poorly understood causes. Within the Northeast Gulf of Mexico, causes of population trends are

  12. Beam losses due to abrupt crab cavity failures in the LHC

    International Nuclear Information System (INIS)

    Baer, T.; Barranco, J.; Calaga, R.; Tomas, R.; Wenninger, B.; Yee, B.; Zimmermann, F.

    2011-01-01

    A major concern for the implementation of crab crossing in a future High-Luminosity LHC (HL-LHC) is machine protection in an event of a fast crab-cavity failure. Certain types of abrupt crab-cavity amplitude and phase changes are simulated to characterize the effect of failures on the beam and the resulting particle-loss signatures. The time-dependent beam loss distributions around the ring and particle trajectories obtained from the simulations allow for a first assessment of the resulting beam impact on LHC collimators and on sensitive components around the ring. Results for the nominal LHC lattice is presented.

  13. Extracellular digestion during hyposaline exposure in the Dungeness crab, Cancer magister, and the blue crab, Callinectes sapidus.

    Science.gov (United States)

    Curtis, Daniel L; van Breukelen, Frank; McGaw, Iain J

    2013-12-01

    Extracellular digestive processes were examined in the Dungeness crab, Cancer magister and the blue crab, Callinectes sapidus, during hyposaline exposure. Both species are found in estuaries as adults, but vary in their ability to balance the cardiovascular and respiratory demands of concurrent osmoregulation and digestion. The weak osmoregulator, C. magister, is unable to balance the demands of osmoregulation and digestion. Concordant with observed decreases in oxygen consumption and mechanical digestion, proteolytic digestion within the foregut and hepatopancreas was delayed, resulting in a relative reduction of circulating amino acids post-feeding in low salinity. In contrast, the efficient osmoregulator, C. sapidus, balances the demands of osmoregulation and digestion, and mechanical digestion continues unabated in low salinity. Protease activity in the gut fluid and hepatopancreas showed either no change or a reduction over time. The transport of amino acids into the cells post-feeding is opposed by an efflux of amino acids at the cellular level, and resulted in a build up of amino acids in the hemolymph. Despite differences in the extracellular responses to low salinity exposure following feeding, both species were able to maintain high digestive efficiencies. © 2013.

  14. A crab swarm at an ecological hotspot: patchiness and population density from AUV observations at a coastal, tropical seamount

    Directory of Open Access Journals (Sweden)

    Jesús Pineda

    2016-04-01

    Full Text Available A research cruise to Hannibal Bank, a seamount and an ecological hotspot in the coastal eastern tropical Pacific Ocean off Panama, explored the zonation, biodiversity, and the ecological processes that contribute to the seamount’s elevated biomass. Here we describe the spatial structure of a benthic anomuran red crab population, using submarine video and autonomous underwater vehicle (AUV photographs. High density aggregations and a swarm of red crabs were associated with a dense turbid layer 4–10 m above the bottom. The high density aggregations were constrained to 355–385 m water depth over the Northwest flank of the seamount, although the crabs also occurred at lower densities in shallower waters (∼280 m and in another location of the seamount. The crab aggregations occurred in hypoxic water, with oxygen levels of 0.04 ml/l. Barcoding of Hannibal red crabs, and pelagic red crabs sampled in a mass stranding event in 2015 at a beach in San Diego, California, USA, revealed that the Panamanian and the Californian crabs are likely the same species, Pleuroncodes planipes, and these findings represent an extension of the southern endrange of this species. Measurements along a 1.6 km transect revealed three high density aggregations, with the highest density up to 78 crabs/m2, and that the crabs were patchily distributed. Crab density peaked in the middle of the patch, a density structure similar to that of swarming insects.

  15. Oribatid mites (Acari: Oribatida) in casts and burrows of an endemic earthworm .i.Dendrobaena mrazeki./i. and in litter of thermophilous oak forests

    Czech Academy of Sciences Publication Activity Database

    Starý, Josef; Pižl, Václav

    2007-01-01

    Roč. 26, č. 4 (2007), s. 390-397 ISSN 1335-342X R&D Projects: GA ČR GA206/03/0056 Institutional research plan: CEZ:AV0Z60660521 Keywords : soil oribatid mites * earthworms * casts and burrows Subject RIV: EH - Ecology, Behaviour Impact factor: 0.085, year: 2005

  16. Flea abundance, diversity, and plague in Gunnison's prairie dogs (Cynomys gunnisoni) and their burrows in montane grasslands in northern New Mexico

    Science.gov (United States)

    Megan M. Friggens; Robert R. Parmenter; Michael Boyden; Paulette L. Ford; Kenneth Gage; Paul Keim

    2010-01-01

    Plague, a flea-transmitted infectious disease caused by the bacterium Yersinia pestis, is a primary threat to the persistence of prairie dog populations (Cynomys spp.). We conducted a 3-yr survey (2004-2006) of fleas from Gunnison's prairie dogs (Cynomys gunnisoni) and their burrows in montane grasslands in Valles Caldera National Preserve in New Mexico. Our...

  17. Locomotory behaviour and functional morphology of Nematostella vectensis (Anthozoa: Actiniaria: Edwardsiidae): a contribution to a comparative study of burrowing behaviour in athenarian sea anemones

    NARCIS (Netherlands)

    Williams, R.B.

    2003-01-01

    The locomotory behaviour and functional morphology of English populations of a small (<2 cm long), burrowing athenarian sea anemone, Nematostella vectensis Stephenson, 1935 (= N. pellucida Crowell, 1946), which lives in soft mud in salt marshes and creeks, are described. Objectives were to ascertain

  18. Feeding and decoration preferences of the epialtidae crab Acanthonyx scutiforms

    Directory of Open Access Journals (Sweden)

    Marcelo Augusto Vasconcelos

    2009-06-01

    Full Text Available Studies on the feeding preferences of marine herbivores are very important for our better understanding of the biology and the ecological role of these organisms. Members of the family Epialtidae are usually herbivores that mask themselves with pieces of seaweed and other materials to avoid predation. In order to better understand the mechanisms of food and decorating choices of the decorator crab Acanthonyx scutiformis, two multiple-choice feeding assays were performed using fresh seaweeds and artificial food containing crude extracts of the four seaweeds Osmundaria obtusiloba, Plocamium brasiliense, Sargassum sp., and Dictyota menstrualis, offered simultaneously to this crab species. In both assays the seaweed most consumed was O. obtusiloba, followed by P. brasiliense and Sargassum sp., while D. menstrualis was the least consumed. It is suggested that A. scutiformis is a generalist feeder, but with some preference for the perennial red seaweed O. obtusiloba and the chemically-defended seaweed P. brasiliense. Decorating behavior observations revealed the preferences of A. scutiformis by P. brasiliense. This decorating behavior can be interpreted as a mechanism to avoid generalist predators, since feeding and decorating preference were not associated and the crab used only small pieces of chemically defended algae.Estudos sobre preferência alimentar de herbívoros marinhos são muito importantes para o melhor entendimento da importância biológica e ecológica destes organismos. Caranguejos majídeos são usualmente herbívoros que se camuflam com pedaços de macroalgas e outros materiais para evitar a predação. Para entender melhor os mecanismos de escolha de alimento e decoração do caranguejo decorador Acanthonyx scutiformis, foram realizados dois ensaios de múltipla escolha usando macroalgas frescas e alimentos artificiais contendo extratos brutos das macroalgas Osmundaria obtusiloba, Plocamium brasiliense, Sargassum sp. e Dictyota

  19. Composite Phymatoderma from Neogene deep-marine deposits in Japan: Implications for Phanerozoic benthic interactions between burrows and the trace-makers of Chondrites and Phycosiphon

    Directory of Open Access Journals (Sweden)

    Kentaro Izumi

    2015-12-01

    Full Text Available Among composite trace fossils, one of the most common structures throughout the Phanerozoic are structures (e.g., dwelling trace, feeding trace reworked by Chondrites and/or Phycosiphon. However, differences in the nature of the reworking behaviors of these two ichnogenera remain unknown. Thus, in this study, composite Phymatoderma specimens from the Neogene deep-marine Shiramazu Formation in Japan, particularly those reworked by Chondrites and Phycosiphon, were analyzed to reveal the specific conditions that might control the activities of these trace-makers. Phymatoderma reworked by Phycosiphon is significantly larger than non-reworked Phymatoderma, whereas Phymatoderma reworked by Chondrites shows no significant difference in burrow diameter compared with non-reworked Phymatoderma. The recognized size selectivity (i.e., preference for larger burrows by the Phycosiphon trace-maker can be explained by considering the different feeding strategies of these two ichnogenera; namely deposit-feeding Phycosiphon-makers, which must have processed a significant mass of sediment to obtain sufficient organic matter, whereas chemosymbiotic Chondrites-producers did not require a lot of sediment to obtain nutrients. In order to test these interpretations, a dataset of Phanerozoic trace fossils reworked by Chondrites/Phycosiphon were compiled. Consequently, the Phycosiphon-producers’ preference toward relatively larger burrows was recognized, quantitatively supporting the results of this study. The compilation also indicates that the burrow size might have become one of the important limiting factors for the Phycosiphon-producers that tried to rework the sediments within previous subsurface burrows, at least for 80 million years.

  20. Burrower bugs (Heteroptera: Cydnidae) in peanut: seasonal species abundance, tillage effects, grade reduction effects, insecticide efficacy, and management.

    Science.gov (United States)

    Chapin, Jay W; Thomas, James S

    2003-08-01

    Pitfall traps placed in South Carolina peanut, Arachis hypogaea (L.), fields collected three species of burrower bugs (Cydnidae): Cyrtomenus ciliatus (Palisot de Beauvois), Sehirus cinctus cinctus (Palisot de Beauvois), and Pangaeus bilineatus (Say). Cyrtomenus ciliatus was rarely collected. Sehirus cinctus produced a nymphal cohort in peanut during May and June, probably because of abundant henbit seeds, Lamium amplexicaule L., in strip-till production systems. No S. cinctus were present during peanut pod formation. Pangaeus bilineatus was the most abundant species collected and the only species associated with peanut kernel feeding injury. Overwintering P. bilineatus adults were present in a conservation tillage peanut field before planting and two to three subsequent generations were observed. Few nymphs were collected until the R6 (full seed) growth stage. Tillage and choice of cover crop affected P. bilineatus populations. Peanuts strip-tilled into corn or wheat residue had greater P. bilineatus populations and kernel-feeding than conventional tillage or strip-tillage into rye residue. Fall tillage before planting a wheat cover crop also reduced burrower bug feeding on peanut. At-pegging (early July) granular chlorpyrifos treatments were most consistent in suppressing kernel feeding. Kernels fed on by P. bilineatus were on average 10% lighter than unfed on kernels. Pangaeus bilineatus feeding reduced peanut grade by reducing individual kernel weight, and increasing the percentage damaged kernels. Each 10% increase in kernels fed on by P. bilineatus was associated with a 1.7% decrease in total sound mature kernels, and kernel feeding levels above 30% increase the risk of damaged kernel grade penalties.

  1. Using ssh as portal - The CMS CRAB over glideinWMS experience

    CERN Document Server

    Belforte, Stefano; Letts, James; Fanzago, Federica; Saiz Santos, Maria Dolores; Martin, Terrence

    2013-01-01

    The User Analysis of the CMS experiment is performed in distributed way usingboth Grid and dedicated resources. In order to insulate the users from the details of computing fabric, CMS relies on the CRAB (CMS Remote Analysis Builder) package as an abstraction layer. CMS has recently switched from a client-server version of CRAB to a purely client-based solution, with ssh being used to interface with HTCondor-based glideinWMS batch system. This switch has resulted in significant improvement of user satisfaction, as well as in significant simplification of the CRAB code base and of the operation support. This paper presents the architecture of the ssh-based CRAB package, the rationale behind it, as well as the operational experience running both the client-server and the ssh-based versions in parallel forseveral months.

  2. Crab and shellfish occurrences in the newly-grown mangrove habitats in southern Thailand

    Science.gov (United States)

    Yeesin, P.; Bautip, S.; Chesoh, S.

    2018-04-01

    Mangrove crabs and shellfish populating in Prince of Songkla University’s new grown mangrove forest were investigated from January 2011 to December 2011 and then repeated annually. A total of 12 species under 6 families of crab and 11 species under 5 families of shellfish were recorded. The most abundant family of crab was Sesarmidae (64.18 %), followed by Ocypodidae, Varunidae, Macrophthalmidae, Portunidae and Dotillidae. Episesarma mederi ( H. Milne Edwards, 1853) showed highest dominant species. In addition, the most dominant family of shellfish was Potamididae (13.79 %), followed by Melampidae, Assimineidae, Onchidiidae and Littorinidae. Sea snail (Cerithidae quadrata; Sowerby, 1866) presented the most dominant coastal mollusc species. Abundance and diversification crabs and mollusks show important component of food web of this type ecosystem. However, only trapped hold samples during low tide were collected but this preliminary finding enables reasonable specified regulation measures.

  3. AFSC/RACE/GAP/Nichol: Archival tag depth and temperature data from snow crab

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Seasonal migration of commercial-size (=102 mm carapace width [CW]), morphometrically mature (MM) snow crabs (Chionoecetes opilio) from the eastern Bering Sea was...

  4. Copulatory behavior of the coconut or robber crab Birgus latro (L. ) (Decapoda anomura, paguridea, coenobitidae)

    Energy Technology Data Exchange (ETDEWEB)

    Helfman, G.S.

    1977-09-01

    In the report, mating in Birgus is described and compared with discriptions of the copulatory behavior of other hermit crabs. Apparently in Birgus, mating is a relatively rare and short event with the time spent in pre-copulatory activities being reduced. There has also been an apparent reduction in the number of behavioral pattern used during courtship. Some of the differences in copulation of the coconut crab may be attributed to an overall adaptation of the species to terrestrial life. For example, the hard exoskeleton of the female could serve in part to reduce desiccation. A reduction in the frequency and duration of copulation could be related to the extremely aggressive intraspecific behavior of Birgus, the crab's high potential for inflicting serious injuries, and the maintenance of an individual distance of approximately one meter. These behavioral traits are in marked contrast to the generalized gregariousness of most hermit crabs, including other members of the family Coenobitidae.

  5. Understanding to Hierarchical Microstructures of Crab (Chinese hairy) Shell as a Natural Architecture

    Energy Technology Data Exchange (ETDEWEB)

    Chuanqiang, Zhou [Testing Center, Yangzhou University, No. 48 Wenhui East Road, Yangzhou (China); Xiangxiang, Gong [Testing Center, Yangzhou University, No. 48 Wenhui East Road, Yangzhou (China); School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou (China); Jie, Han [School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou (China)

    2016-03-07

    This work was done to better understand the microstructures, composition and mechanical properties of Chinese hairy crab shell. For fully revealing its hierarchical microstructure, the crab shell was observed with electron microscope under different magnifications from different facets. XRD, EDS, FTIR and TGA techniques have been used to characterize the untreated and chemically-treated crab shells, which provided enough information to determine the species and relative content of components in this biomaterial. Combined the microstructures with constituents analysis, the structural principles of crab shell was detailedly realized from different structural levels beyond former reports. To explore the relationship between structure and function, the mechanical properties of shell have been measured through performing tensile tests. The contributions of organics and minerals in shell to the mechanical properties were also discussed by measuring the tensile strength of de-calcification samples treated with HCl solution.

  6. On the misidentification of a common sandy beach crab belonging to ...

    African Journals Online (AJOL)

    1992-07-09

    Jul 9, 1992 ... three-spot swimming crab, a member of the genus Ovalipes. Rathbun, 1898. Members ... coastal and estuarine waters of temperate oceans and are especially .... salinity and temperature tolerances of its zoeae. S. Afr. J. Zool.

  7. Preliminary Observations on the Uptake of Poliovirus by West Coast Shore Crabs

    Science.gov (United States)

    DiGirolamo, Rudolph; Wiczynski, Leokadia; Daley, Michael; Miranda, Florencio

    1972-01-01

    West Coast shore crabs (Pachygrapsus sp. and Hemigrapsus sp.), when in seawater contaminated with poliovirus or allowed to feed on virus-contaminated mussels (Mytilus californianus), were found to accumulate high titers of virus. PMID:4333894

  8. AFSC/RACE/SAP/Cummiskey: Red king crab sonic tagging and dive database

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This is data from a long-term monitoring project which utilized sonic tags to follow aggregations of red king crab in Womens Bay near Kodiak Alaska. The database...

  9. Fecundity of the Indian Horse-shoe crab, Carcinoscorpius rotundicauda (Latreille)

    Digital Repository Service at National Institute of Oceanography (India)

    Chatterji, A.; Parulekar, A.H.

    and per g ovary weight were 48, 18 and 164 respectively. Maximum fecundity was observed in crabs ranging in size from 174-179 mm. Relationships between fecundity, carapace length, body weight and ovary weight were linear...

  10. AFSC/RACE/SAP/Swiney: Red king crab fecundity and embryo and larval quality

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Stock assessment of Alaskan red king crab, Paralithodes camtschaticus (Tilesius, 1815), can be improved by incorporating reproductive output, which requires an...

  11. AFSC/RACE/SAP/Munk: Life history studies of Tanner crab, Chionoecetes bairdi, near Kodiak, Alaska.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — From 1994 through 2012 Tanner crab were identified as premolt, held through a molt, and then measured to determine growth per molt.

  12. AFSC/RACE/SAP/Foy: Effects of ocean acidification on larval Tanner crab: Kodiak Island, Alaska.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — To study the effects of ocean acidification we examined the effects of ocean acidification on the larval stages of the economically important southern Tanner crab,...

  13. Long-term in vitro generation of amoebocytes from the Indian horseshoe crab Tachypleus gigas (Muller)

    Digital Repository Service at National Institute of Oceanography (India)

    Joshi, B.; Chatterji, A.; Bhonde, R.

    Amoebocyte is the single type of cell circulating in the horseshoe crab hemolymph, which plays a major role in the defense system of the animal. Granules present in these cells are sensitive to nanogram quantities of bacterial endotoxins, which form...

  14. Gut-Associated Microbial Symbionts of the Marsh Fiddler Crab, Uca Pugnax

    National Research Council Canada - National Science Library

    Gunman, Lara K

    2004-01-01

    .... The overarching goal of this thesis was to characterize the ecology and genetic diversity of resident gut microbes to advance our understanding of their interactions with their host, the marsh fiddler crab, Uca pugnax...

  15.  The diversity of horseshoe crabs - protecting an endangered resource

    DEFF Research Database (Denmark)

    Funch, Peter; Cong, Nguyen Van; Intanai, Itsara

    Horseshoe crabs are fascinating inhabitants of the sea represented by four living species, where three species live in Asia, while the fourth species lives on the East coast of North America. Ancient fossils, dating back to Ordovician 445 million years ago looks so similar to recent horseshoe crabs...... that people often call them "living fossils". Unfortunately, the existing populations are threatened by overfishing of the adults as well as by destruction and pollution of the beaches where they mate and deposit their eggs. All four extant species are on IUCN Red List of Threatened Species. The blue blood...... of the horseshoe crabs saves thousands of human lives every year. An extract from their blood are used worldwide to determine whether medicine, blood donations, and medical supplies are infected by bacteria or contain toxins. Horseshoe crabs are also fished for human consumption in Asia, are heavily used as bait...

  16. Sterol biosynthesis from acetate and the fate of dietary cholesterol and desmosterol in crabs

    International Nuclear Information System (INIS)

    Teshima, Shin-ichi; Kanazawa, Akio; Okamoto, Haruhito

    1976-01-01

    This paper deals with the sterol-synthesizing ability and the fate of dietary sterols, cholesterol and desmosterol, in the crabs, Sesarma dehaani and Helice tridens. Injected acetate-1- 14 C was not incorporated into either squalene or sterols in the above crabs. This suggested that the sterol-synthesizing ability from acetate is absent or weak in the crabs, S. dehaani and H. tridens. The apparent percentage absorptions of dietary cholesterol and desmosterol from the digestive tracts were 91.9 and 90.9, respectively. The ingested cholesterol and desmosterol were metabolized to steryl esters and polar compounds but only slightly to water-soluble sterols. Also, it was shown that the crab, S. dehaani, is capable of converting desmosterol to cholesterol. (auth.)

  17. Understanding to Hierarchical Microstructures of Crab (Chinese hairy) Shell as a Natural Architecture

    International Nuclear Information System (INIS)

    Chuanqiang, Zhou; Xiangxiang, Gong; Jie, Han

    2016-01-01

    This work was done to better understand the microstructures, composition and mechanical properties of Chinese hairy crab shell. For fully revealing its hierarchical microstructure, the crab shell was observed with electron microscope under different magnifications from different facets. XRD, EDS, FTIR and TGA techniques have been used to characterize the untreated and chemically-treated crab shells, which provided enough information to determine the species and relative content of components in this biomaterial. Combined the microstructures with constituents analysis, the structural principles of crab shell was detailedly realized from different structural levels beyond former reports. To explore the relationship between structure and function, the mechanical properties of shell have been measured through performing tensile tests. The contributions of organics and minerals in shell to the mechanical properties were also discussed by measuring the tensile strength of de-calcification samples treated with HCl solution

  18. Feeding behaviour and food selection in the horseshoe crab, Tachypleus gigas (Muller)

    Digital Repository Service at National Institute of Oceanography (India)

    Chatterji, A; Mishra, J.K.; Parulekar, A

    The Indian horseshoe crab, Tachypleus gigas, is a benthic feeder which subsists mainly on molluscs, decayed organic matter and polychaetes, in order of prevalence. A strong and positive preference was recorded for molluscs over other food organisms...

  19. Energy source in the developing eggs of the Indian horseshoe crab, Tachypleus gigas (Muller)

    Digital Repository Service at National Institute of Oceanography (India)

    Chatterji, A.; Aguiar, Q.; Saldanha, C.

    Wet weight, dry weight, water content, ash weight, soluble and insoluble proteins, carbohydrates, lipids, and glycogen were determined from 0 to 40th day after fertilization of the developing eggs of the Indian horseshoe crab, Tachypleus gigas...

  20. CRAB3: Establishing a new generation of services for distributed analysis at CMS

    CERN Document Server

    Spiga, Daniele

    2012-01-01

    In CRAB3 all work is centrally injected and managed in a global queue. A pool of agents, which can be geographically distributed, consumes work from the central services, servicing the user tasks. The new gener...

  1. An association between a lip arid fish species and the stone crab ...

    African Journals Online (AJOL)

    1986-07-19

    Jul 19, 1986 ... FiSh eggs, thought to be Ihose of the llparid fish, Careproctus grise/dea, were found In the gill chambers of several specimens 01 the stone crab, Lithodes tropical/s, caught in deep-water (~ m) oil the South West. African/Namibian coast (-24°46'Sl13°28'E). The size class and quantity of crabs involved in this ...

  2. Food sources for the mangrove tree crab aratus pisonii: a carbon isotopic study

    International Nuclear Information System (INIS)

    Lacerda, L.D.; Silva, C.A.R.; Rezende, C.E.; Martinelli, L.A.

    1991-01-01

    Muscle tissues from the mangrove tree crab Aratus pisonii was analysed for carbon isotopic composition, in order to trace its major food sources. Potential food sources: mangrove leaves epi phytic green algae, mangrove sediments and open water and mangrove suspended matter; were also analysed. The results show that A. pisonii is basically omnivorous, with major food sources from marine origin. However, mangrove carbon can contribute with 16% to 42% in the crab's diet. (author)

  3. Metabolomic analysis of marine and mud crabs based on antibacterial activity

    Directory of Open Access Journals (Sweden)

    A.A. Laith

    2017-08-01

    Full Text Available Isolated compounds from marine invertebrates are being increasingly known to possess various pharmacological activities with which many useful drugs have been developed. Crabs contain bioactive compounds including antibacterial, antifungal and antiviral metabolites, isolated from various tissues and organs that have revolutionized treatment of serious diseases. The present study represents the first attempt to investigate and compare the natural antibacterial properties from whole extract of marine blue swimmer crab, Portunus pelagicus, and mud crab, Scylla tranquebarica, against fish pathogenic bacteria. Liquid chromatography/mass spectrometry utilizing a time-of-flight (TOF mass analyser (LC/MS-QTOF based metabolomics approach was used to characterize the variation in secondary metabolite production in P. pelagicus and S. tranquebarica crab habitats in Malaysia. Different metabolites are evaluated in both crab species using LC/MS-QTOF. Initially a total of 75 metabolites were identified and only 19 metabolites satisfied the P-Corr cut-off point of less than 0.01 and at least 2-fold change. These metabolites, which contain anti-inflammatory and antibacterial properties, were down regulated in S. tranquebarica samples and up regulated in P. pelagicus samples. In vitro bioassay of methanolic P. pelagicus extracts showed the best antimicrobial response against Gram positive bacteria, Streptococcus agalactiae, and Gram negative bacteria, Vibrio alginolyticus, Klebsiella pneumoniae, and Escherichia coli, with a statistically significant difference (P < 0.05 of P. pelagicus extracts as compared to S. tranquebarica. The results indicate that both types of crab extracts are bactericidal at higher concentrations and bacteriostatic at lower concentrations. This manuscript reports the role of marine and mud crabs with specific emphasis on their secondary metabolites, and discusses current and future developments in both the production of desired crab

  4. Lung function and prevalence of respiratory symptoms in Norwegian crab processing workers

    OpenAIRE

    Thomassen, Marte Renate; Aasmoe, Lisbeth; Bang, Berit E.; Braaten, Tonje

    2017-01-01

    Source at http://dx.doi.org/10.1080/22423982.2017.1313513 Background: Seafood processing workers have an increased risk of developing occupational asthma. This has not been studied among Norwegian crab processing workers, nor has the respiratory health of exposed workers been compared to a control group. Objectives: Assessing the impact of working in the crab processing industry on workers ’ respiratory health. Design: A cross-sectional study of the respiratory health i...

  5. The bioeconomic impact of different management regulations on the Chesapeake Bay blue crab fishery

    Science.gov (United States)

    Bunnell, David B.; Lipton, Douglas W.; Miller, Thomas J.

    2010-01-01

    The harvest of blue crabs Callinectes sapidus in Chesapeake Bay declined 46% between 1993 and 2001 and remained low through 2008. Because the total market value of this fishery has declined by an average of US $ 3.3 million per year since 1993, the commercial fishery has been challenged to maintain profitability. We developed a bioeconomic simulation model of the Chesapeake Bay blue crab fishery to aid managers in determining which regulations will maximize revenues while ensuring a sustainable harvest. We compared 15 different management scenarios, including those implemented by Maryland and Virginia between 2007 and 2009, that sought to reduce female crab harvest and nine others that used seasonal closures, different size regulations, or the elimination of fishing for specific market categories. Six scenarios produced the highest revenues: the 2008 and 2009 Maryland regulations, spring and fall closures for female blue crabs, and 152- and 165-mm maximum size limits for females. Our most important finding was that for each state the 2008 and 2009 scenarios that implemented early closures of the female crab fishery produced higher revenues than the 2007 scenario, in which no early female closures were implemented. We conclude that the use of maximum size limits for female crabs would not be feasible despite their potentially high revenue, given the likelihood that the soft-shell and peeler fisheries cannot be expanded beyond their current capacity and the potentially high mortality rate for culled individuals that are the incorrect size. Our model results support the current use of seasonal closures for females, which permit relatively high exploitation of males and soft-shell and peeler blue crabs (which have high prices) while keeping the female crab harvest sustainable. Further, our bioeconomic model allows for the inclusion of an economic viewpoint along with biological data when target reference points are set by managers.

  6. Measurement of the crab flux above 60 GeV with the celeste Cerenkov telescope

    Czech Academy of Sciences Publication Activity Database

    Naurois De, M.; Holder, J.; Bazer-Bachi, R.; Bergeret, H.; Bruel, P.; Cordier, A.; Debais, G.; Dezalay, J. P.; Dumora, D.; Durand, E.; Eschstruth, P.; Espigat, P.; Fabre, B.; Fleury, P.; Hérault, N.; Hrabovský, Miroslav; Incerti, S.; Le Gallou, R.; Moenz, F.; Musquére, A.; Olive, J. F.; Paré, E.; Québert, J.; Rannot, R. C.; Reposeur, T.; Rob, L.; Roy, P.; Sako, T.; Schovánek, Petr; Smith, D. A.; Snabre, P.; Volte, A.

    2002-01-01

    Roč. 566, - (2002), s. 343-357 ISSN 0004-637X R&D Projects: GA ČR GA202/97/1181 Institutional research plan: CEZ:AV0Z1010920 Keywords : gamma ray: observations * ISM:individual (Crab Nebula) * pulsar :individual (Crab Pulsar ) * supernova remnants Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 6.187, year: 2002

  7. Beam-Beam Simulation of Crab Cavity White Noise for LHC Upgrade

    CERN Document Server

    Qiang, J; Pieloni, Tatiana; Ohmi, Kazuhito

    2015-01-01

    High luminosity LHC upgrade will improve the luminosity of the current LHC operation by an order of magnitude. Crab cavity as a critical component for compensating luminosity loss from large crossing angle collision and also providing luminosity leveling for the LHC upgrade is being actively pursued. In this paper, we will report on the study of potential effects of the crab cavity white noise errors on the beam luminosity lifetime based on strong-strong beam-beam simulations.

  8. Fast crab cavity failures in HL-LHC

    CERN Document Server

    Yee-Rendon, B; Calaga, R; Tomas, R; Zimmermann, F; Barranco, J

    2014-01-01

    Crab cavities (CCs) are a key ingredient of the High-Luminosity Large Hadron Collider (HL-LHC) to ensure head on collisions at the main experiments (ATLAS and CMS) and fully profit from the smaller provided by the ATS optics [1]. At KEKB, CCs have exhibited abrupt changes of phase and voltage during a time period of few LHC turns and considering the large energy stored in the HL-LHC beam, CC failures represent a serious risk to the LHC machine protection. In this paper, we discuss the effect of CC voltage or phase changes on a time interval similar to, or longer than, the one needed to dump the beam. The simulations assume a realistic steady-state distribution to assess the beam losses for the HL-LHC. Additionally, some strategies are studied in order to reduce the damage caused by the CC failures.

  9. Gamma-ray flares from the Crab Nebula.

    Science.gov (United States)

    Abdo, A A; Ackermann, M; Ajello, M; Allafort, A; Baldini, L; Ballet, J; Barbiellini, G; Bastieri, D; Bechtol, K; Bellazzini, R; Berenji, B; Blandford, R D; Bloom, E D; Bonamente, E; Borgland, A W; Bouvier, A; Brandt, T J; Bregeon, J; Brez, A; Brigida, M; Bruel, P; Buehler, R; Buson, S; Caliandro, G A; Cameron, R A; Cannon, A; Caraveo, P A; Casandjian, J M; Çelik, Ö; Charles, E; Chekhtman, A; Cheung, C C; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Costamante, L; Cutini, S; D'Ammando, F; Dermer, C D; de Angelis, A; de Luca, A; de Palma, F; Digel, S W; do Couto e Silva, E; Drell, P S; Drlica-Wagner, A; Dubois, R; Dumora, D; Favuzzi, C; Fegan, S J; Ferrara, E C; Focke, W B; Fortin, P; Frailis, M; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Gehrels, N; Germani, S; Giglietto, N; Giordano, F; Giroletti, M; Glanzman, T; Godfrey, G; Grenier, I A; Grondin, M-H; Grove, J E; Guiriec, S; Hadasch, D; Hanabata, Y; Harding, A K; Hayashi, K; Hayashida, M; Hays, E; Horan, D; Itoh, R; Jóhannesson, G; Johnson, A S; Johnson, T J; Khangulyan, D; Kamae, T; Katagiri, H; Kataoka, J; Kerr, M; Knödlseder, J; Kuss, M; Lande, J; Latronico, L; Lee, S-H; Lemoine-Goumard, M; Longo, F; Loparco, F; Lubrano, P; Madejski, G M; Makeev, A; Marelli, M; Mazziotta, M N; McEnery, J E; Michelson, P F; Mitthumsiri, W; Mizuno, T; Moiseev, A A; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nakamori, T; Naumann-Godo, M; Nolan, P L; Norris, J P; Nuss, E; Ohsugi, T; Okumura, A; Omodei, N; Ormes, J F; Ozaki, M; Paneque, D; Parent, D; Pelassa, V; Pepe, M; Pesce-Rollins, M; Pierbattista, M; Piron, F; Porter, T A; Rainò, S; Rando, R; Ray, P S; Razzano, M; Reimer, A; Reimer, O; Reposeur, T; Ritz, S; Romani, R W; Sadrozinski, H F-W; Sanchez, D; Saz Parkinson, P M; Scargle, J D; Schalk, T L; Sgrò, C; Siskind, E J; Smith, P D; Spandre, G; Spinelli, P; Strickman, M S; Suson, D J; Takahashi, H; Takahashi, T; Tanaka, T; Thayer, J B; Thompson, D J; Tibaldo, L; Torres, D F; Tosti, G; Tramacere, A; Troja, E; Uchiyama, Y; Vandenbroucke, J; Vasileiou, V; Vianello, G; Vitale, V; Wang, P; Wood, K S; Yang, Z; Ziegler, M

    2011-02-11

    A young and energetic pulsar powers the well-known Crab Nebula. Here, we describe two separate gamma-ray (photon energy greater than 100 mega-electron volts) flares from this source detected by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. The first flare occurred in February 2009 and lasted approximately 16 days. The second flare was detected in September 2010 and lasted approximately 4 days. During these outbursts, the gamma-ray flux from the nebula increased by factors of four and six, respectively. The brevity of the flares implies that the gamma rays were emitted via synchrotron radiation from peta-electron-volt (10(15) electron volts) electrons in a region smaller than 1.4 × 10(-2) parsecs. These are the highest-energy particles that can be associated with a discrete astronomical source, and they pose challenges to particle acceleration theory.

  10. An earlier explosion date for the Crab Nebula supernova

    Science.gov (United States)

    Abt, Helmut A.; Fountain, John W.

    2018-04-01

    The Chinese first reported the Crab Nebula supernova on 1054 July 5. Ecclesiastical documents from the near east reported it in April and May of 1054. More than 33 petroglyphs made by Native Americans in the US and Mexico are consistent with sightings both before and after conjunction with the Sun on 1054 May 27. We found a petroglyph showing the new star close to Venus and the Moon, which occurred on 1054 April 12 and April 13, respectively. Collins et al., using the four historical dates, derived a light curve that is like that of a Type Ia supernova. The only remaining problem with this identification is that this supernova was near maximum light for 85 d, which is unlike the behavior of any known supernova.

  11. Niche construction drives social dependence in hermit crabs.

    Science.gov (United States)

    Laidre, Mark E

    2012-10-23

    Organisms can receive not only a genetic inheritance from their ancestors but also an ecological inheritance, involving modifications their ancestors made to the environment through niche construction. Ecological inheritances may persist as a legacy, potentially generating selection pressures that favor sociality. Yet, most proposed cases of sociality being impacted by an ecological inheritance come from organisms that live among close kin and were highly social before their niche construction began. Here, I show that in terrestrial hermit crabs (Coenobita compressus)--organisms that do not live with kin and reside alone, each in its own shell--niche-construction drives social dependence, such that individuals can only survive in remodeled shells handed down from conspecifics. These results suggest that niche construction can be an important initiator of evolutionary pressures to socialize, even among unrelated and otherwise asocial organisms. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. Renegotiating property rights in the Florida golden crab fishery

    Directory of Open Access Journals (Sweden)

    Scott Crosson

    2013-08-01

    Full Text Available The golden crab (Chaceon fenneri supports a small, economically healthy fishery in south Florida. Crabbers in the fishery have successfully protected themselves against larger outside fishing interests in the past, and management has been stable for over fifteen years.  Why, then, did a portion of the fleet propose shifting to individual transferable quotas (ITQs?  Our findings suggest that proponents sought ITQ management because they believed it would further limit the ability of other crabbers to enter the fishery and act as a mechanism to legally preserve the informal and formal property rights that they have previously negotiated among themselves. Opponents believed that a shift to an ITQ regime would destroy those same property rights.  We explore the implications of these findings to a broader understanding of property rights and natural resource management institutions, noting that the currently existing system closely resembles a territorial use rights fishery (TURF.

  13. Prey capture by the crab spider Misumena calycina (Araneae: Thomisidae).

    Science.gov (United States)

    Morse, Douglass H

    1979-01-01

    Crab spiders Misumena calycina (L.) in pasture rose Rosa carolina flowers regularly attacked bumble bees, smaller bees, and syrphid flies that visited these flowers. Attacks reached a maximum rate of over 20/h during mid morning, but only 1.6% of the most important prey item, bumble bees, were captured. The next most important food source, the most frequently taken item, syrphid flies Toxomerus marginatus (Say), were captured in 39% of the attempts. Since these flies have a biomass only 1/60th that of bumble bees, they comprised a much less important food source than did bumble bees. Spiders would obtain over 7% more food by specializing on bumble bees than by attacking all insect visitors, and as much as 20% more food at certain times of the day. However, they did not show a tendency to specialize at any time.

  14. Confinement of the crab pulsar's wind by its supernova remnant

    International Nuclear Information System (INIS)

    Kennel, C.F.; Coroniti, F.V.

    1984-01-01

    We construct a steady state, spherically symmetric, magnetohydrodynamic model of the Crab nebual. A highly relativistic, positronic pulsar wind is terminated by a strong MHD shock that decelerates the flow and increases its pressure to match boundary conditions imposed by the recently discovered supernova remnant that surrounds the nebula. If the magnetic luminosity of the pulsar wind upsteam of the shock is about 0.3% of its particle luminosity, the pressure and velocity boundary conditions imposed by the remnant place the shock where we infer it to be; near the outer boundary of an underluminous region observed to surround the pulsar. It is necessary to include the weak magnetization of the wind to satisfy the boundary conditions and to calculate the nebular synchrotron radiation self-consistently

  15. Gamma-ray flares from the Crab nebula

    International Nuclear Information System (INIS)

    Abdo, A.A.; Ackermann, M.; Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J.; Casandjian, J.M.; Grenier, I.A.; Naumann-Godo, M.; Pierbattista, M.; Tibaldo, L.

    2011-01-01

    A young and energetic pulsar powers the well-known Crab Nebula. Here, we describe two separate gamma-ray (photon energy greater than 100 mega-electron volts) flares from this source detected by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. The first flare occurred in February 2009 and lasted approximately 16 days. The second flare was detected in September 2010 and lasted approximately 4 days. During these outbursts, the gamma-ray flux from the nebula increased by factors of four and six, respectively. The brevity of the flares implies that the gamma rays were emitted via synchrotron radiation from peta-electron-volt (10 15 electron volts) electrons in a region smaller than 1.4 * 10 -2 parsecs. These are the highest-energy particles that can be associated with a discrete astronomical source, and they pose challenges to particle acceleration theory. (authors)

  16. Evolution of the magnetic field structure of the Crab pulsar.

    Science.gov (United States)

    Lyne, Andrew; Graham-Smith, Francis; Weltevrede, Patrick; Jordan, Christine; Stappers, Ben; Bassa, Cees; Kramer, Michael

    2013-11-01

    Pulsars are highly magnetized rotating neutron stars and are well known for the stability of their signature pulse shapes, allowing high-precision studies of their rotation. However, during the past 22 years, the radio pulse profile of the Crab pulsar has shown a steady increase in the separation of the main pulse and interpulse components at 0.62° ± 0.03° per century. There are also secular changes in the relative strengths of several components of the profile. The changing component separation indicates that the axis of the dipolar magnetic field, embedded in the neutron star, is moving toward the stellar equator. This evolution of the magnetic field could explain why the pulsar does not spin down as expected from simple braking by a rotating dipolar magnetic field.

  17. Science support for evaluating natural recovery of polychlorinated biphenyl concentrations in fish from Crab Orchard Lake, Crab Orchard National Wildlife Refuge, Illinois

    Science.gov (United States)

    Kunz, Bethany K.; Hinck, Jo E.; Calfee, Robin D.; Linder, Greg L.; Little, Edward E.

    2018-05-11

    IntroductionCrab Orchard Lake in southern Illinois is one of the largest and most popular recreational lakes in the state. Construction of the nearly 7,000-acre reservoir in the late 1930s created employment opportunities through the Works Progress Administration, and the lake itself was intended to supply water, control flooding, and provide recreational opportunities for local communities (Stall, 1954). In 1942, the Department of War appropriated or purchased more than 20,000 acres of land around Crab Orchard Lake and constructed the Illinois Ordnance Plant, which manufactured bombs and anti-tank mines during World War II. After the war, an Act of Congress transferred the property to the U.S. Department of the Interior. Crab Orchard National Wildlife Refuge was established on August 5, 1947, for the joint purposes of wildlife conservation, agriculture, recreation, and industry. Production of explosives continued, but new industries also moved onsite. More than 200 tenants have held leases with Crab Orchard National Wildlife Refuge and have operated a variety of manufacturing plants (electrical components, plated metal parts, ink, machined parts, painted products, and boats) on-site. Soils, water, and sediments in several areas of the refuge were contaminated with hazardous substances from handling and disposal methods that are no longer acceptable environmental practice (for example, direct discharge to surface water, use of unlined landfills).Polychlorinated biphenyl (PCB) contamination at the refuge was identified in the 1970s, and a PCB-based fish-consumption advisory has been in effect since 1988 for Crab Orchard Lake. The present advisory covers common carp (Cyprinus carpio) and channel catfish (Ictalurus punctatus); see Illinois Department of Public Health (2017). Some of the most contaminated areas of the refuge were actively remediated, and natural ecosystem recovery processes are expected to further reduce residual PCB concentrations in the lake. The U

  18. Trophic discrimination of stable isotopes and potential food source partitioning by leaf-eating crabs in mangrove environments

    DEFF Research Database (Denmark)

    Kristensen, Erik; Lee, Shing Yip; Mangion, Perrine

    2017-01-01

    Diet composition of leaf-eating mangrove crabs is a puzzle among mangrove ecologists. Nutrient-poor leaf litter can in most cases not support animal growth. Food partitioning (mangrove leaves, animal tissue, and microphytobenthos [MPB]) of sesarmid and ucidid mangrove crabs from eight locations...... here for crabs foraging on leaf litter to identify discrimination values that provide a balanced diet with sufficient nutrients (i.e., N) when combined with other food sources. The data from all mangrove locations suggest that sesarmid and ucidid crabs ingest and assimilate mixtures of available food...... is probably caused by metabolic disparities between these two crab families. Deviations in 15N discrimination have in most cases only minor influence on the model-based 13C discrimination thresholds. The present findings lead us to suggest a modified Optimal Foraging Theory for leaf-eating mangrove crabs....

  19. Developmental ecology of the American horseshoe crab Limulus polyphemus

    Directory of Open Access Journals (Sweden)

    Mark L. BOTTON, Richard A. TANKERSLEY, Robert E. LOVELAND

    2010-10-01

    Full Text Available During spawning events, horseshoe crab eggs are released from the female’s oviducts, and fertilized by one or more males. Eggs are shaped by the female into discrete clutches deposited in nests at depths of 10-20 cm on intertidal estuarine beaches. Distinguishing between fresh eggs and the early developmental stages is obfuscated by the large amount of dense, opaque yolk. The first unambiguous confirmation of development is the formation of the rudimentary prosomatic appendages at the “limb bud” stage. Several days thereafter, the outer chorion is shed and the developing embryo expands and undergoes a series of molts within the clear inner egg membrane. The trilobite (first instar stage thus attained may remain within the beach sediments for several more weeks, until hatching is facilitated by environmental factors such as hydration, agitation, and osmotic shock that accompany the infiltration of seawater into the nests. Trilobites exhibit endogenous circatidal swimming rhythms that are entrained by mechanical agitation, suggesting that peaks in larval swimming are timed to coincide with periods of high water and the inundation of the nests. Larval swimming is limited and does not appear to result in long-distance dispersal. The limited dispersal of the larvae has important implications for the population dynamics of relatively isolated populations. The rate of larval development is highly plastic and is influenced by temperature, salinity, dissolved oxygen, and the presence of pollutants. The broad environmental tolerances of horseshoe crab embryos and larvae are important in understanding their current geographic distribution and their evolutionary persistence [Current Zoology 56 (5: 550–562, 2010].

  20. Absolute quantification method and validation of airborne snow crab allergen tropomyosin using tandem mass spectrometry

    International Nuclear Information System (INIS)

    Rahman, Anas M. Abdel; Lopata, Andreas L.; Randell, Edward W.; Helleur, Robert J.

    2010-01-01

    Measuring the levels of the major airborne allergens of snow crab in the workplace is very important in studying the prevalence of crab asthma in workers. Previously, snow crab tropomyosin (SCTM) was identified as the major aeroallergen in crab plants and a unique signature peptide was identified for this protein. The present study advances our knowledge on aeroallergens by developing a method of quantification of airborne SCTM by using isotope dilution mass spectrometry. Liquid chromatography tandem mass spectrometry was developed for separation and analysis of the signature peptides. The tryptic digestion conditions were optimized to accomplish complete digestion. The validity of the method was studied using international conference on harmonization protocol, Where 2-9% for CV (precision) and 101-110% for accuracy, at three different levels of quality control. Recovery of the spiked protein from PTFE and TopTip filters was measured to be 99% and 96%, respectively. To further demonstrate the applicability and the validity of the method for real samples, 45 kg of whole snow crab were processed in an enclosed (simulated) crab processing line and air samples were collected. The levels of SCTM ranged between 0.36-3.92 μg m -3 and 1.70-2.31 μg m -3 for butchering and cooking stations, respectively.

  1. Responses of the crab Heterozius rotundifrons to heterospecific chemical alarm cues: phylogeny vs. ecological overlap.

    Science.gov (United States)

    Hazlett, Brian A; McLay, Colin

    2005-03-01

    The big-handed brachyuran crab Heterozius rotundifrons extends the time spent in its anti-predator posture, limb extended posture, if exposed to chemical cues from crushed conspecifics. In this study, we tested whether crabs also respond to chemical cues from crushed heterospecific crabs, and if so, whether phylogenetic relations or ecological overlap is more important in influencing the duration of the anti-predator posture. Chemical cues from two other brachyuran crabs (Cyclograpsus lavauxi and Hemigrapsus sexdentatus), which do not overlap directly in ecological distribution with H. rotundifrons, elicited a duration of the anti-predator posture that was indistinguishable from that produced by conspecific chemical cues. In contrast, chemical cues from two anomuran crabs (Petrolisthes elongatus and Pagurus novizealandiae) that overlap in ecological distribution with H. rotundifrons, elicited durations of the antipredator posture that were significantly shorter than those of either conspecifics or more closely related crab species. Thus, phylogenetic relationship seems to be more important than ecological overlap in influencing anti-predator behavior in H. rotundifrons.

  2. Present and Potential Future Distributions of Asian Horseshoe Crabs Determine Areas for Conservation

    Directory of Open Access Journals (Sweden)

    Stine Vestbo

    2018-05-01

    Full Text Available Conservation of horseshoe crabs has recently received increasing attention as several populations are in decline. However, scarce information on their distributions in Southeast Asia is impairing conservation efforts. In this study, we sought to improve our understanding of the geographical range and distinct populations of the three Asian horseshoe crabs species in order to identify optimal conservation areas. We mapped the geographic range of Carcinoscorpius rotundicauda, Tachypleus gigas, and T. tridentatus using recent data from field work, literature, Global Biodiversity Information Facility (GBIF, and unpublished data from our scientific network. The data were correlated with 23 different environmental variables of potential ecological importance for horseshoe crabs using the openModeller webservices, including new tidal variables. Ecological niche models were generated using two algorithms, Maximum Entropy and support vector machine, for the three species under present conditions, and projected into a climate change scenario of 2050. The niches of the Asian horseshoe crabs were mostly determined by tidal regime, chlorophyll A concentrations, depth, distance to land, and sea surface temperature. According to our predictions, horseshoe crabs in Southeast Asia are not expected to experience any severe change in extent and distribution of suitable habitat in the future. In order to conserve Asian horseshoe crabs, we suggest establishing Marine Protected Areas at locations where distinct populations and several species occur, such as northern Vietnam, China, Borneo, and southern Japan.

  3. Reproductive biology of the female Jonah crab from the Maryland-Virginia Coastal Zone

    Science.gov (United States)

    Dunn, H.; Stevens, B. G.

    2016-02-01

    Jonah crabs, Cancer borealis, have long been considered a bycatch of the lobster industry. Jonah crab harvest is not regulated, there are no fishing size limits, nor restrictions to protect females. The study sampled Jonah crabs from one area in the Maryland-Virginia coastal zone from a local fishing vessel in June and July of 2015. This study is based on examination of the gross anatomy of 49 crabs and on histological preparations from 29 crabs. Ovary development stages were created and ordered based on area of oocytes, color and size of ovary, and the presence of sperm plugs. Four stages were observed but five are identifiable. Size at 50% sexual maturity (SM50), for females, as indicated by vulvar condition and oocyte area, was estimated to be 49.46 mm carapace length (CL). No prior information or study has been published concerning female Jonah crabs. This fishery-independent data is vital to ensure long-term sustainability, and develop appropriate management for this species.

  4. Resources Management Strategy For Mud Crabs (Scylla spp.) In Pemalang Regency

    Science.gov (United States)

    Purnama Fitri, Aristi Dian; Boesono, Herry; Sabdono, Agus; Adlina, Nadia

    2017-02-01

    The aim of this research is to develop resources management strategies of mud crab (Scylla spp.) in Pemalang Regency. The method used is descriptive survey in a case study. This research used primary data and secondary data. Primary data were collected through field observations and in-depth interviews with key stakeholders. Secondary data were collected from related publications and documents issued by the competent institutions. SWOT Analysis was used to inventory the strengths, weaknesses, opportunities and threats. TOWS matrix was used to develop an alternative of resources management strategies. SWOT analysis was obtained by 6 alternative strategies that can be applied for optimization of fisheries development in Pemalang Regency. The strategies is the control of mud crab fishing gear, restricted size allowable in mud crab, control of mud crab fishing season, catch monitoring of mud crab, needs a management institutions which ensure the implementation of the regulation, and implementation for mud crab aquaculture. Each alternative strategy can be synergized to optimize the resources development in Pemalang Regency.

  5. Sustainable fisheries in shallow lakes: an independent empirical test of the Chinese mitten crab yield model

    Science.gov (United States)

    Wang, Haijun; Liang, Xiaomin; Wang, Hongzhu

    2017-07-01

    Next to excessive nutrient loading, intensive aquaculture is one of the major anthropogenic impacts threatening lake ecosystems. In China, particularly in the shallow lakes of mid-lower Changjiang (Yangtze) River, continuous overstocking of the Chinese mitten crab ( Eriocheir sinensis) could deteriorate water quality and exhaust natural resources. A series of crab yield models and a general optimum-stocking rate model have been established, which seek to benefit both crab culture and the environment. In this research, independent investigations were carried out to evaluate the crab yield models and modify the optimum-stocking model. Low percentage errors (average 47%, median 36%) between observed and calculated crab yields were obtained. Specific values were defined for adult crab body mass (135 g/ind.) and recapture rate (18% and 30% in lakes with submerged macrophyte biomass above and below 1 000 g/m2) to modify the optimum-stocking model. Analysis based on the modified optimum-stocking model indicated that the actual stocking rates in most lakes were much higher than the calculated optimum-stocking rates. This implies that, for most lakes, the current stocking rates should be greatly reduced to maintain healthy lake ecosystems.

  6. Effects of fenoxycarb exposure on complete larval development of the xanthid crab, Rhithropanopeus harrisii

    International Nuclear Information System (INIS)

    Cripe, G.M.; McKenney, C.L.; Hoglund, M.D.; Harris, P.S.

    2003-01-01

    The pest control agent fenoxycarb reduced survival and extended duration of developing larval stages in the xanthid crab, Rhithropanopeus harrisii. - Pest control agents, such as juvenile hormone analogues (JHA), have been developed to limit effects on non-target organisms that co-inhabit insect pest habitats. Rhithropanopeus harrisii, an estuarine xanthid crab, was used to observe the impacts of the JHA, fenoxycarb, on the pattern of complete larval development as well as survival of larvae and successful metamorphosis to first crab stage. Significant mortality occurred in the first of four zoeal stages (after 2-3 days of exposure) at the highest treatment of 240 μg fenoxycarb/l and in megalopae exposed to 48 μg fenoxycarb/l. The time required to metamorphose to the first crab stage was significantly increased for megalopae in all treatments ≥48 μg/l. This delay in development was sufficient to significantly prolong the entire developmental period from zoea to crabs. Unexposed larvae developed to crabs in an average of 16 days; larvae exposed to ≥48 μg/l required 19-20 days. Reduced survival and extended duration of developing larval stages in the life history of a benthic invertebrate may alter the population dynamics of these organisms in the estuary

  7. American alligator digestion rate of blue crabs and its implications for stomach contents analysis

    Science.gov (United States)

    Nifong, James C.; Rosenblatt, Adam E.; Johnson, Nathan A.; Barichivich, William; Silliman, Brian; Heithaus, Michael R.

    2012-01-01

    Stomach contents analysis (SCA) provides a snap-shot observation of a consumer's diet. Interpretation of SCA data can be complicated by many factors, including variation in gastric residence times and digestion rates among prey taxa. Although some SCA methods are reported to efficiently remove all stomach contents, the effectiveness of these techniques has rarely been tested for large irregular shaped prey with hard exoskeletons. We used a controlled feeding trial to estimate gastric residency time and decomposition rate of a large crustacean prey item, the Blue Crab (Callinectes sapidus), which is consumed by American Alligators (Alligator mississippiensis), an abundant apex predator in coastal habitats of the southeastern United States. The decomposition rate of C. sapidus in the stomachs of A. mississippiensis followed a predictable pattern, and some crab pieces remained in stomachs for at least 14 days. We also found that certain portions of C. sapidus were prone to becoming caught within the stomach or esophagus, meaning not all crab parts are consistently recovered using gastric lavage techniques. However, because the state of decomposition of crabs was predictable, it is possible to estimate time since consumption for crabs recovered from wild alligators. This information, coupled with a detailed understanding of crab distributions and alligator movement tactics could help elucidate patterns of cross-ecosystem foraging by the American Alligator in coastal habitats

  8. Absolute quantification method and validation of airborne snow crab allergen tropomyosin using tandem mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, Anas M. Abdel, E-mail: anasar@mun.ca [Department of Chemistry, Memorial University of Newfoundland, St. John' s, Newfoundland A1B 3X7 (Canada); Lopata, Andreas L. [School of Applied Science, Marine Biomedical Sciences and Health Research Group, RMIT University, Bundoora, 3083 Victoria (Australia); Randell, Edward W. [Department of Laboratory Medicine, Memorial University of Newfoundland, Eastern Health, St. John' s, Newfoundland and Labrador A1B 3V6 (Canada); Helleur, Robert J. [Department of Chemistry, Memorial University of Newfoundland, St. John' s, Newfoundland A1B 3X7 (Canada)

    2010-11-29

    Measuring the levels of the major airborne allergens of snow crab in the workplace is very important in studying the prevalence of crab asthma in workers. Previously, snow crab tropomyosin (SCTM) was identified as the major aeroallergen in crab plants and a unique signature peptide was identified for this protein. The present study advances our knowledge on aeroallergens by developing a method of quantification of airborne SCTM by using isotope dilution mass spectrometry. Liquid chromatography tandem mass spectrometry was developed for separation and analysis of the signature peptides. The tryptic digestion conditions were optimized to accomplish complete digestion. The validity of the method was studied using international conference on harmonization protocol, Where 2-9% for CV (precision) and 101-110% for accuracy, at three different levels of quality control. Recovery of the spiked protein from PTFE and TopTip filters was measured to be 99% and 96%, respectively. To further demonstrate the applicability and the validity of the method for real samples, 45 kg of whole snow crab were processed in an enclosed (simulated) crab processing line and air samples were collected. The levels of SCTM ranged between 0.36-3.92 {mu}g m{sup -3} and 1.70-2.31 {mu}g m{sup -3} for butchering and cooking stations, respectively.

  9. Effects of fenoxycarb exposure on complete larval development of the xanthid crab, Rhithropanopeus harrisii

    Energy Technology Data Exchange (ETDEWEB)

    Cripe, G.M.; McKenney, C.L.; Hoglund, M.D.; Harris, P.S

    2003-09-01

    The pest control agent fenoxycarb reduced survival and extended duration of developing larval stages in the xanthid crab, Rhithropanopeus harrisii. - Pest control agents, such as juvenile hormone analogues (JHA), have been developed to limit effects on non-target organisms that co-inhabit insect pest habitats. Rhithropanopeus harrisii, an estuarine xanthid crab, was used to observe the impacts of the JHA, fenoxycarb, on the pattern of complete larval development as well as survival of larvae and successful metamorphosis to first crab stage. Significant mortality occurred in the first of four zoeal stages (after 2-3 days of exposure) at the highest treatment of 240 {mu}g fenoxycarb/l and in megalopae exposed to 48 {mu}g fenoxycarb/l. The time required to metamorphose to the first crab stage was significantly increased for megalopae in all treatments {>=}48 {mu}g/l. This delay in development was sufficient to significantly prolong the entire developmental period from zoea to crabs. Unexposed larvae developed to crabs in an average of 16 days; larvae exposed to {>=}48 {mu}g/l required 19-20 days. Reduced survival and extended duration of developing larval stages in the life history of a benthic invertebrate may alter the population dynamics of these organisms in the estuary.

  10. Hypolobocera guayaquilensis (Decapoda: Pseudothelphusidae): A New Crab Intermediate Host of Paragonimus mexicanus in Manabí Province, Ecuador

    Science.gov (United States)

    Calvopina, Manuel; Romero-Alvarez, Daniel; Rendon, Melina; Takagi, Hidekazu; Sugiyama, Hiromu

    2018-01-01

    To determine that Paragonimus sp. is actively transmitted in a tropical area of the Pacific region of Ecuador where human cases of pulmonary paragonimiasis have recently been documented, a total of 75 freshwater crabs were collected from 2 different streams in the Pedernales area of Manabí Province, Ecuador. All collected crabs were identified as Hypolobocera guayaquilensis based on morphological characteristics of the male gonopods. The hepatopancreas of each crab was examined by compressing it between 2 glass plates followed by observation under a stereomicroscope. Excysted Paragonimus metacercariae were detected in 39 (52.0%) crabs and their densities varied from 1 to 32 per infected crab. There was a positive relationship between crab size and metacercarial density. Sequences of the second internal transcribed spacer region of the ribosomal RNA gene of the Paragonimus metacercariae obtained in this study were identical to those of Paragonimus mexicanus deposited in the DDBJ/EMBL/GenBank database. Thus, the present study is the first to confirm that the crab species H. guayaquilensis is the second intermediate host of P. mexicanus in Manabí Province, Ecuador. Because this crab might be the possible source of human infections in this area, residents should pay attention to improper crab-eating habits related with a neglected parasitic disease, i.e., paragonimiasis. PMID:29742874

  11. Dungeness Crab Dredging Entrainment Studies in the Lower Columbia River, 2002 – 2004: Loss Projections, Salinity Model, and Scenario Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Pearson, Walter H.; Williams, Greg D.; Skalski, John R.

    2005-01-01

    Dungeness crab studies conducted in 2002 for the Portland District of the U.S. Army Corps of Engineers (Corps) constituted a major step forward in quantifying crab entrainment through statistical projections of adult equivalent loss (AEL) and loss to the fishery (LF) from proposed construction and maintenance dredging in the Columbia River navigation channel (Pearson et al. 2002, 2003). These studies also examined the influence of bottom salinity on crab abundance and entrainment rates. Additional sampling was conducted in 2004 to tighten loss projections, further develop the crab salinity model, and apply the model to assess correlations of entrainment rates and projected losses with seasonal salinity changes.

  12. Movement patterns and trajectories of ovigerous blue crabs Callinectes sapidus during the spawning migration

    Science.gov (United States)

    Carr, Sarah D.; Tankersley, Richard A.; Hench, James L.; Forward, Richard B.; Luettich, Richard A.

    2004-08-01

    Female blue crabs ( Callinectes sapidus Rathbun) migrate from low salinity estuarine regions to high salinity regions near the ocean to release larvae. During this migration, ovigerous females use ebb-tide transport, a vertical migratory behavior in which they ascend into the water column during ebb tides, to move seaward to larval release areas. In order to determine the relationship of ebb-tide vertical migrations to local currents and the influence of these vertical migrations on the horizontal transport of blue crabs in the estuary, ovigerous females with mature embryos (˜1-3 days from hatching) were tracked near Beaufort Inlet, North Carolina (USA), in July and August 2001 and 2002. Crabs were tagged and tracked using ultrasonic telemetry, and currents near the crabs were measured simultaneously with a shipboard acoustic Doppler current profiler. During the two seasons, eight crabs were successfully tracked for periods ranging from 3.9-37.0 h and for distances ranging from 1.9-10.6 km. All crabs migrated seaward during the tracking periods. Crabs moved episodically during all tidal phases with periods of movement on the order of minutes to an hour. They moved with local currents in terms of both speed and direction during ebb tides, consistent with ebb-tide transport, and moved down-estuary (seaward) in opposition to local currents during flood tides. The percentage of time that crabs were active was higher during night ebb tides than during day ebb tides or flood tides and increased with increasing ebb-tide current speed. Mean migratory speeds were 0.11, 0.04, 0.08 and 0.02 m s -1 during night ebb, night flood, day ebb and day flood tides, respectively, and net migratory speeds were on the order of 5 km day -1. Due to the episodic nature of the crabs' movements, the total distances that crabs traveled during ebb tides ranged from 10-40% of the distances that passive particles could have traveled under the same conditions.

  13. Consumption patterns and risk assessment of crab consumers from the Newark Bay Complex, New Jersey, USA.

    Science.gov (United States)

    Pflugh, Kerry Kirk; Stern, Alan H; Nesposudny, Laura; Lurig, Lynette; Ruppel, Bruce; Buchanan, Gary A

    2011-10-01

    The Newark Bay Complex (NBC) is a significant historical repository of polychlorinated dibenzodioxins (PCDDs) and dioxin-like compounds. Detection of high levels of 2,3,7,8 tetrachloro-dibenzodioxins (TCDD) and its toxicological equivalents in blue crabs in the early 1990's led to a ban on the taking and distribution of crabs from the NBC. Despite this ban and ongoing communication outreach, surveys of crabbers in 1995, 2002 and 2005 by the New Jersey Department of Environmental Protection (NJDEP) showed that crabbing for recreational purposes and for significant dietary supplementation was continuing. At the time they were surveyed, the crabbers had been consuming these crabs for an average of 37% of their lives. Thus, exposure can be considered chronic. The surveys provided data on the duration, frequency and amount of NBC crab consumption. In 2004, the NJDEP sampled blue crabs in the NBC and analyzed the edible portions for 2,3,7,8 TCDD toxicity equivalent (TEQ) concentration. We have combined the survey-based exposure data and the 2,3,7,8 TCDD TEQ concentration data to produce an estimate of the lifetime cancer risk to NBC crabbers from dioxin-like compounds. We employed a point-estimate approach using discrete lower, central tendency and reasonable maximum exposure (RME) estimates of exposure factors and a probabilistic approach to exposure factors. Both approaches show central tendency lifetime cancer risk of greater than one-in-a-thousand (10(-3)) and an upper percentile/RME risk of approximately one-in-a-hundred (10(-2)). Little extrapolation is involved in applying the 2,3,7,8-TCDD TEQ concentration data in crabs to risk estimates in the population consuming those crabs. The ongoing and frequent nature of the crab collection minimizes the uncertainty often inherent in food recall surveys. These estimates point to the continued risk posed to NBC crab consumers and to the continuing importance of this resource which, with proper remediation, could provide

  14. AFSC/RACE/SAP: Detailed Crab Data From NOAA Fisheries Service Annual Eastern Bering Sea Summer Bottom Trawl Surveys 1975 - 2015

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains detailed crab data collected from the annual NOAA/NMFS/AFSC/RACE crab-groundfish bottom trawl survey of the eastern Bering Sea continental...

  15. Impacts of Habitat Complexity on Physiology: Purple Shore Crabs Tolerate Osmotic Stress for Shelter

    Science.gov (United States)

    McGaw, I. J.

    2001-12-01

    Purple shore crabs, Hemigrapsus nudus (Crustacea: Decapoda), can survive indefinitely in salinities of 8 (25% SW), but also tolerate short-term exposure to salinities as low as 2. In the laboratory their salinity preference range, determined from choice chamber experiments, is 22-32 and they can discriminate between pairs of salinities separated by a difference of 2. These crabs show a strong positive thigmotaxis and a weak negative phototaxis and tend to choose environments with available shelter. The presence of shelter significantly alters the behaviour of this species. When shelter is available the salinity preference range is 10-32. Even in salinities below this preference range, the presence of shelter prolongs the time spent in the lower test salinities. This change in behaviour has implications on the crab's physiology: the haemolymph osmolality falls to lower levels when crabs remain in low salinity under shelters. In the field, H. nudus is found in creeks with salinities close to freshwater and they may remain in this salinity for up to 11 h, if there are rocks under which to shelter. An increase in habitat complexity increases the number of crabs that are found within the creek. These crabs in the low salinity environment have a lower haemolymph osmolality than crabs on the nearby open shore. In H. nudus the behavioural selection of a shelter appears to outweigh the physiological costs associated with osmotic regulation of the body fluids. Therefore, the distribution of H. nudus in estuaries may depend more on the availability of suitable habitats rather than the salinity tolerance of this species.

  16. Endogenous cellulase production in the leaf litter foraging mangrove crab Parasesarma erythodactyla.

    Science.gov (United States)

    Bui, T H Hanh; Lee, Shing Yip

    2015-01-01

    The sesarmid crab Parasesarma erythodactyla consumes large amounts of mangrove leaf litter but its biochemical capacity for cellulose digestion is poorly known. We demonstrate the presence of endo-β-1,4-glucanase, β-glucosidase and total cellulase activities in the digestive juice of this crab. The highest total cellulase activity was observed at mildly acidic pH (5 to 6) and temperature between 30 and 50°C. A 1752bp cDNA containing an open reading frame of 1386bp encoding a putative endo-β-1,4-glucanase (EG) of 461 amino acids was identified in the crab's hepatopancreas using polymerase chain reaction (PCR), cloning and sequencing techniques. P. erythodactyla endo-β-1,4-glucanase (PeEG) contains a glycosyl hydrolase family 9 (GHF9) catalytic domain with all catalytically important residues conserved, and shows high sequence identity to GHF9 EGs reported from other arthropods. The endogenous origin of PeEG was confirmed by PCR amplification of a ~1.5kb DNA fragment, containing a phase 1 intron flanked by two exon sequences identical to the cDNA, from genomic DNA isolated from the crab's muscle tissue. PeEG encoding cDNA is the first endogenous EG sequence reported from the brachyuran crabs. Using degenerate primers, we also isolated 204bp cDNA fragments with sequences affiliated to EG from the hepatopancreas of eight other mangrove crabs of the Sesarmidae (Neosarmatium trispinosum and Sesarmoides borneensis), Macrophthalmidae (Ilyograpsus daviei, Australoplax tridentata, and Macrophthalmus setosus), Varunidae (Pseudohelice subquadrata), Heloeciidae (Heloecius cordiformis), and Ocypodidae (Uca perplexa) families, suggesting that endogenous cellulase production may be a common characteristic among the detritivorous mangrove crabs. Copyright © 2014 Elsevier Inc. All rights reserved.

  17. Interference competition as a key determinant for spatial distribution of mangrove crabs

    KAUST Repository

    Cannicci, Stefano

    2018-02-15

    The spatial distribution of mangrove crabs has been commonly associated with tree zonation and abiotic factors such as ground temperature and soil granulometry. Conversely, no studies were designed to investigate the role of competition for resources and predation in shaping crab distribution in mangroves, despite these biotic factors are recognised as key determinants for spatial patterns observed in the communities colonising rocky and sandy intertidal habitats.We studied floral and faunal assemblages in two zones of a Sri Lankan mangrove, a man-made upper intertidal level and a natural eulittoral, mid-shore one. Leaf choice experiments were designed to study both feeding rate and intra and inter-specific interactions for food of sesarmid crabs in the two habitats in order to better understand crab spatial distribution.The two intertidal belts differed in terms of floral composition and crab species abundance. The eulittoral zone was strongly dominated by Neosarmatium smithi, while within the elevated littoral fringe four sesarmids (N. smithi, N. asiaticum, N. malabaricum and Muradium tetragonum) were more evenly distributed. At both levels, all sesarmids showed to collect significantly more Bruguiera spp. and Rhizophora apiculata leaves than Excoecaria agallocha ones. There was no temporal segregation in feeding activity among the four species, resulting in a high interference competition for leaves. Regardless of the habitat, N. smithi was always successful in winning inter-specific fights.Our results showed that the elevated littoral fringe was more crowded with crabs, but was less favourable in terms of food availability and environmental conditions. The dominance of N. smithi in gathering mangrove leaves suggests that this species may segregate the other sesarmids into less favourable habitats. The present data strongly suggest for the first time that interference competition for food can contribute to shape mangrove crab spatial distribution.

  18. Electroless nickel – phosphorus coating on crab shell particles and its characterization

    Energy Technology Data Exchange (ETDEWEB)

    Arulvel, S., E-mail: gs.arulvel.research@gmail.com; Elayaperumal, A.; Jagatheeshwaran, M.S.

    2017-04-15

    Being hydrophilic material, crab shell particles have only a limited number of applications. It is, therefore, necessary to modify the surface of the crab shell particles. To make them useful ever for the applications, the main theme we proposed in this article is to utilize crab shell particles (CSP) with the core coated with nickel phosphorus (NiP) as a shell using the electroless coating process. For dealing with serious environmental problems, utilization of waste bio-shells is always an important factor to be considered. Chelating ability of crab shell particles eliminates the surface activation in this work proceeding to the coating process. The functional group, phase structure, microstructure, chemical composition and thermal analysis of CSP and NiP/CSP were characterized using Fourier transform infra-red spectroscopy (FTIR), x-ray diffraction analyzer (XRD), scanning electron microscope (SEM), energy-dispersive x-ray spectroscopy (EDS), and thermogravimetric analysis (TGA). The combination of an amorphous and crystalline structure was exhibited by CSP and NiP/CSP. NiP/CSP has shown a better thermal stability when compared to uncoated CSP. Stability test, adsorption test, and conductivity test were conducted for the study of adsorption behavior and conductivity of the particles. CSP presented a hydrophilic property in contrast to hydrophobic NiP/CSP. NiP/CSP presented a conductivity of about 44% greater compared to the CSP without any fluctuations. - Highlights: • Utilization of crab shell waste is focused on. • NiP coating on crab shell particle is fabricated using electroless process. • Thermal analysis, stability test, adsorption test and conductivity test were done. • Organic matrix of crab shell particle favors the coating process. • Results demonstrate the characterization of CSP core – NiP shell structure.

  19. Interference competition as a key determinant for spatial distribution of mangrove crabs

    KAUST Repository

    Cannicci, Stefano; Fusi, Marco; Cimó , Filippo; Dahdouh-Guebas, Farid; Fratini, Sara

    2018-01-01

    The spatial distribution of mangrove crabs has been commonly associated with tree zonation and abiotic factors such as ground temperature and soil granulometry. Conversely, no studies were designed to investigate the role of competition for resources and predation in shaping crab distribution in mangroves, despite these biotic factors are recognised as key determinants for spatial patterns observed in the communities colonising rocky and sandy intertidal habitats.We studied floral and faunal assemblages in two zones of a Sri Lankan mangrove, a man-made upper intertidal level and a natural eulittoral, mid-shore one. Leaf choice experiments were designed to study both feeding rate and intra and inter-specific interactions for food of sesarmid crabs in the two habitats in order to better understand crab spatial distribution.The two intertidal belts differed in terms of floral composition and crab species abundance. The eulittoral zone was strongly dominated by Neosarmatium smithi, while within the elevated littoral fringe four sesarmids (N. smithi, N. asiaticum, N. malabaricum and Muradium tetragonum) were more evenly distributed. At both levels, all sesarmids showed to collect significantly more Bruguiera spp. and Rhizophora apiculata leaves than Excoecaria agallocha ones. There was no temporal segregation in feeding activity among the four species, resulting in a high interference competition for leaves. Regardless of the habitat, N. smithi was always successful in winning inter-specific fights.Our results showed that the elevated littoral fringe was more crowded with crabs, but was less favourable in terms of food availability and environmental conditions. The dominance of N. smithi in gathering mangrove leaves suggests that this species may segregate the other sesarmids into less favourable habitats. The present data strongly suggest for the first time that interference competition for food can contribute to shape mangrove crab spatial distribution.

  20. Ocean Acidification Affects Hemocyte Physiology in the Tanner Crab (Chionoecetes bairdi)

    Science.gov (United States)

    Meseck, Shannon L.; Alix, Jennifer H.; Swiney, Katherine M.; Long, W. Christopher; Wikfors, Gary H.; Foy, Robert J.

    2016-01-01

    We used flow cytometry to determine if there would be a difference in hematology, selected immune functions, and hemocyte pH (pHi), under two different, future ocean acidification scenarios (pH = 7.50, 7.80) compared to current conditions (pH = 8.09) for Chionoecetes bairdi, Tanner crab. Hemocytes were analyzed after adult Tanner crabs were held for two years under continuous exposure to acidified ocean water. Total counts of hemocytes did not vary among control and experimental treatments; however, there were significantly greater number of dead, circulating hemocytes in crabs held at the lowest pH treatment. Phagocytosis of fluorescent microbeads by hemocytes was greatest at the lowest pH treatment. These results suggest that hemocytes were dying, likely by apoptosis, at a rate faster than upregulated phagocytosis was able to remove moribund cells from circulation at the lowest pH. Crab hemolymph pH (pHe) averaged 8.09 and did not vary among pH treatments. There was no significant difference in internal pH (pHi) within hyalinocytes among pH treatments and the mean pHi (7.26) was lower than the mean pHe. In contrast, there were significant differences among treatments in pHi of the semi-granular+granular cells. Control crabs had the highest mean semi-granular+granular pHi compared to the lowest pH treatment. As physiological hemocyte functions changed from ambient conditions, interactions with the number of eggs in the second clutch, percentage of viable eggs, and calcium concentration in the adult crab shell was observed. This suggested that the energetic costs of responding to ocean acidification and maintaining defense mechanisms in Tanner crab may divert energy from other physiological processes, such as reproduction. PMID:26859148

  1. Snow crab allergy and asthma among Greenlandic workers – a pilot study

    Directory of Open Access Journals (Sweden)

    Jakob Hjort Bønløkke

    2012-08-01

    Full Text Available Objectives. To study snow crab sensitization, occupational allergy and asthma in the snow crab industry in Greenland, as high rates have been found in Canada, but no reports have emerged from the same industry in Greenland. Study design. Pilot survey. Methods. Twenty workers (19 of Inuit and 1 of other origin in a snow crab (Chionoecetes opilio and Atlantic shrimp (Pandalus borealis processing plant in Greenland were assessed with skin prick tests (SPTs with common aeroallergens and specific allergens from snow crab and shrimp extracts, spirometry, blood sampling for total IgE and specific IgE determination. Eighteen workers contributed a questionnaire-based medical interview. Results. Positive skin prick test reactions were common to snow crab (40% and shrimp (20%. Specific IgE to snow crab were positive in 4 workers (21%. Two workers had elevated total IgE levels. Symptoms suggestive of asthma were common (45%. Work-related symptoms of skin rash, rhinitis, and/or conjunctivitis were reported by 50%, and symptoms from the lower airways by 39%. Combining history of work-related symptoms with results from specific SPTs and/or specific IgE determination suggested that 11 and 22% of workers suffered from probable and possible occupational asthma, respectively, whereas 22% had possible occupational dermatitis or rhinitis. Conclusions. Greenlander Inuit do not appear to be protected against sensitization to snow crab or shrimp when occupationally exposed to these. This pilot study suggests that occupational allergy and asthma may be as common a problem in Greenlandic workers as in Canadian.

  2. Enhancement of the immune response and protection against Vibrio parahaemolyticus by indigenous probiotic Bacillus strains in mud crab (Scylla paramamosain).

    Science.gov (United States)

    Wu, Hui-Juan; Sun, Ling-Bin; Li, Chuan-Biao; Li, Zhong-Zhen; Zhang, Zhao; Wen, Xiao-Bo; Hu, Zhong; Zhang, Yue-Ling; Li, Sheng-Kang

    2014-12-01

    In a previous study, bacterial communities of the intestine in three populations of crabs (wild crabs, pond-raised healthy crabs and diseased crabs) were probed by culture-independent methods. In this study, we examined the intestinal communities of the crabs by bacterial cultivation with a variety of media. A total of 135 bacterial strains were isolated from three populations of mud crabs. The strains were screened for antagonistic activity against Vibrio parahaemolyticus using an agar spot assay. Antagonistic strains were then identified by 16S rRNA gene sequence analysis. Three strains (Bacillus subtilis DCU, Bacillus pumilus BP, Bacillus cereus HL7) with the strongest antagonistic activity were further evaluated for their probiotic characteristics. The results showed that two (BP and DCU) of them were able to survive low pH and high bile concentrations, showed good adherence characteristics and a broad spectrum of antibiotic resistance. The probiotic effects were then tested by feeding juvenile mud crabs (Scylla paramamosain) with foods supplemented with 10(5) CFU/g of BP or DCU for 30 days before being subjected to an immersion challenge with V. parahaemolyticus for 48 h. The treated crabs showed significantly higher expression levels of immune related genes (CAT, proPO and SOD) and activities of respiratory burst than that in controlled groups. Crabs treated with BP and DCU supplemented diets exhibited survival rates of 76.67% and 78.33%, respectively, whereas survival rate was 54.88% in crabs not treated with the probiotics. The data showed that indigenous mud-associated microbiota, such as DCU and BP, have potential application in controlling pathogenic Vibriosis in mud crab aquaculture. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. The importance of scale-dependent ravine characteristics on breeding-site selection by the Burrowing Parrot, Cyanoliseus patagonus

    Directory of Open Access Journals (Sweden)

    Myriam Ramirez-Herranz

    2017-04-01

    Full Text Available In birds, the environmental variables and intrinsic characteristics of the nest have important fitness consequences through its influence on the selection of nesting sites. However, the extent to which these variables interact with variables that operate at the landscape scale, and whether there is a hierarchy among the different scales that influences nest-site selection, is unknown. This interaction could be crucial in burrowing birds, which depend heavily on the availability of suitable nesting locations. One representative of this group is the burrowing parrot, Cyanoliseus patagonus that breeds on specific ravines and forms large breeding colonies. At a particular site, breeding aggregations require the concentration of adequate environmental elements for cavity nesting, which are provided by within ravine characteristics. Therefore, intrinsic ravine characteristics should be more important in determining nest site selection compared to landscape level characteristics. Here, we assess this hypothesis by comparing the importance of ravine characteristics operating at different scales on nest-site selection and their interrelation with reproductive success. We quantified 12 characteristics of 105 ravines in their reproductive habitat. For each ravine we quantified morphological variables, distance to resources and disturbance as well as nest number and egg production in order to compare selected and non-selected ravines and determine the interrelationship among variables in explaining ravine differences. In addition, the number of nests and egg production for each reproductive ravine was related to ravine characteristics to assess their relation to reproductive success. We found significant differences between non-reproductive and reproductive ravines in both intrinsic and extrinsic characteristics. The multidimensional environmental gradient of variation between ravines, however, shows that differences are mainly related to intrinsic

  4. A GIANT SAMPLE OF GIANT PULSES FROM THE CRAB PULSAR

    International Nuclear Information System (INIS)

    Mickaliger, M. B.; McLaughlin, M. A.; Lorimer, D. R.; Palliyaguru, N.; Langston, G. I.; Bilous, A. V.; Kondratiev, V. I.; Lyutikov, M.; Ransom, S. M.

    2012-01-01

    We observed the Crab pulsar with the 43 m telescope in Green Bank, WV over a timespan of 15 months. In total we obtained 100 hr of data at 1.2 GHz and seven hours at 330 MHz, resulting in a sample of about 95,000 giant pulses (GPs). This is the largest sample, to date, of GPs from the Crab pulsar taken with the same telescope and backend and analyzed as one data set. We calculated power-law fits to amplitude distributions for main pulse (MP) and interpulse (IP) GPs, resulting in indices in the range of 2.1-3.1 for MP GPs at 1.2 GHz and in the range of 2.5-3.0 and 2.4-3.1 for MP and IP GPs at 330 MHz. We also correlated the GPs at 1.2 GHz with GPs from the Robert C. Byrd Green Bank Telescope (GBT), which were obtained simultaneously at a higher frequency (8.9 GHz) over a span of 26 hr. In total, 7933 GPs from the 43 m telescope at 1.2 GHz and 39,900 GPs from the GBT were recorded during these contemporaneous observations. At 1.2 GHz, 236 (3%) MP GPs and 23 (5%) IP GPs were detected at 8.9 GHz, both with zero chance probability. Another 15 (4%) low-frequency IP GPs were detected within one spin period of high-frequency IP GPs, with a chance probability of 9%. This indicates that the emission processes at high and low radio frequencies are related, despite significant pulse profile shape differences. The 43 m GPs were also correlated with Fermi γ-ray photons to see if increased pair production in the magnetosphere is the mechanism responsible for GP emission. A total of 92,022 GPs and 393 γ-ray photons were used in this correlation analysis. No significant correlations were found between GPs and γ-ray photons. This indicates that increased pair production in the magnetosphere is likely not the dominant cause of GPs. Possible methods of GP production may be increased coherence of synchrotron emission or changes in beaming direction.

  5. A GIANT SAMPLE OF GIANT PULSES FROM THE CRAB PULSAR

    Energy Technology Data Exchange (ETDEWEB)

    Mickaliger, M. B.; McLaughlin, M. A.; Lorimer, D. R.; Palliyaguru, N. [Department of Physics, West Virginia University, Morgantown, WV 26506 (United States); Langston, G. I. [National Radio Astronomy Observatory, Green Bank, WV 24944 (United States); Bilous, A. V. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904 (United States); Kondratiev, V. I. [Netherlands Institute for Radio Astronomy (ASTRON), Postbus 2, 7990 AA Dwingeloo (Netherlands); Lyutikov, M. [Department of Physics, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907-2036 (United States); Ransom, S. M. [National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States)

    2012-11-20

    We observed the Crab pulsar with the 43 m telescope in Green Bank, WV over a timespan of 15 months. In total we obtained 100 hr of data at 1.2 GHz and seven hours at 330 MHz, resulting in a sample of about 95,000 giant pulses (GPs). This is the largest sample, to date, of GPs from the Crab pulsar taken with the same telescope and backend and analyzed as one data set. We calculated power-law fits to amplitude distributions for main pulse (MP) and interpulse (IP) GPs, resulting in indices in the range of 2.1-3.1 for MP GPs at 1.2 GHz and in the range of 2.5-3.0 and 2.4-3.1 for MP and IP GPs at 330 MHz. We also correlated the GPs at 1.2 GHz with GPs from the Robert C. Byrd Green Bank Telescope (GBT), which were obtained simultaneously at a higher frequency (8.9 GHz) over a span of 26 hr. In total, 7933 GPs from the 43 m telescope at 1.2 GHz and 39,900 GPs from the GBT were recorded during these contemporaneous observations. At 1.2 GHz, 236 (3%) MP GPs and 23 (5%) IP GPs were detected at 8.9 GHz, both with zero chance probability. Another 15 (4%) low-frequency IP GPs were detected within one spin period of high-frequency IP GPs, with a chance probability of 9%. This indicates that the emission processes at high and low radio frequencies are related, despite significant pulse profile shape differences. The 43 m GPs were also correlated with Fermi {gamma}-ray photons to see if increased pair production in the magnetosphere is the mechanism responsible for GP emission. A total of 92,022 GPs and 393 {gamma}-ray photons were used in this correlation analysis. No significant correlations were found between GPs and {gamma}-ray photons. This indicates that increased pair production in the magnetosphere is likely not the dominant cause of GPs. Possible methods of GP production may be increased coherence of synchrotron emission or changes in beaming direction.

  6. Gender and snow crab occupational asthma in Newfoundland and Labrador, Canada

    International Nuclear Information System (INIS)

    Howse, Dana; Gautrin, Denyse; Neis, Barbara; Cartier, Andre; Horth-Susin, Lise; Jong, Michael; Swanson, Mark C.

    2006-01-01

    Fish and shellfish processing employs many thousands of people globally, with shellfish processing becoming more important in recent years. Shellfish processing is associated with multiple occupational health and safety (OHS) risks. Snow crab occupational asthma (OA) is work-related asthma associated with processing snow crab. We present a gender analysis of findings from a 3-year multifaceted study of snow crab OA in Newfoundland and Labrador, Canada. The study was carried out in four snow crab processing communities between 2001 and 2004. An anonymous survey questionnaire on knowledge, beliefs, and concerns related to processing snow crab administered to 158 workers attending community meetings at the start of the research found that women were significantly more likely than men to associate certain health problems, especially chest tightness, difficulty breathing, and cough, with crab processing (P<0.001). Worker health assessments carried out with 215 processing workers (187 current/28 former; 120 female/95 male) found that female participants were more likely to be diagnosed as almost certain/highly probable snow crab OA and allergy (P=0.001) and to be sensitized to snow crab (P=0.01) than male participants. Work histories from the health assessments were used to classify processing jobs as male or female. Allergen sampling (211 allergen samples: 115 area, 96 personal breathing zone) indicated that the plant areas where these male jobs were concentrated were associated with lower levels of aerosolized crab allergens (the agents responsible for OA to snow crab) than areas associated with female jobs. This difference was statistically significant in the two plants with poor ventilation (p<0.001 and P=0.017 for these plants). A gender analysis of work history data showed that female health assessment participants were likely to have worked longer processing snow crab than males (5 years versus 3.5 years, respectively). Cross-referencing of work history results

  7. Assessing potential impacts of energized submarine power cables on crab harvests

    Science.gov (United States)

    Love, Milton S.; Nishimoto, Mary M.; Clark, Scott; McCrea, Merit; Bull, Ann Scarborough

    2017-12-01

    Offshore renewable energy facilities transmit electricity to shore through submarine power cables. Electromagnetic field emissions (EMFs) are generated from the transmission of electricity through these cables, such as the AC inter-array (between unit) and AC export (to shore) cables often used in offshore energy production. The EMF has both an electric component and a magnetic component. While sheathing can block the direct electric field, the magnetic field is not blocked. A concern raised by fishermen on the Pacific Coast of North America is that commercially important Dungeness crab (Metacarcinus magister Dana, 1852)) might not cross over an energized submarine power cable to enter a baited crab trap, thus potentially reducing their catch. The presence of operating energized cables off southern California and in Puget Sound (cables that are comparable to those within the arrays of existing offshore wind energy devices) allowed us to conduct experiments on how energized power cables might affect the harvesting of both M. magister and another commercially important crab species, Cancer productus Randall, 1839. In this study we tested the questions: 1) Is the catchability of crabs reduced if these animals must traverse an energized power cable to enter a trap and 2) if crabs preferentially do not cross an energized cable, is it the cable structure or the EMF emitted from that cable that deters crabs from crossing? In field experiments off southern California and in Puget Sound, crabs were given a choice of walking over an energized power cable to a baited trap or walking directly away from that cable to a second baited trap. Based on our research we found no evidence that the EMF emitted by energized submarine power cables influenced the catchability of these two species of commercially important crabs. In addition, there was no difference in the crabs' responses to lightly buried versus unburied cables. We did observe that, regardless of the position of the cable

  8. Diversity and distribution of Dorippid Crabs (Brachyura: Dorippidae) in East Coast of Lampung, Indonesia

    Science.gov (United States)

    Zairion; Hakim, AA; Mashar, A.; Fahrudin, A.; Adrianto, L.; Widigdo, B.; Wardiatno, Y.

    2018-05-01

    Dorippid crabs (Brachyura: Dorippidae) commonly live in sand or mud substrate at shallow coastal water. These crabs are a macro-benthos, mostly found in tropic, have no economic value, but have high abundance in blue swimming crab habitat and lack information in Indonesia. This study aims to determine diversity and species distribution of dorippid crabs in East Coast of Lampung, Indonesia. This study was conducted on March-April 2017 in seven locations along coastal area (i.e. Labuhan Maringgai, Kuala Penet, Sekopong, Wako, Seputih, Sungai Burung, and Kuala Teladas). The specimen was collected from the blue swimming crab gill-net fishery as by-catch. Each location found by this family was noted at coordinate point at satellite imagery map and processed using ArcGIS. Two species have been found, there are Dorippe quadridens and Dorippoides facchino. Both species were found at every location, except D. quadridens at Sungai Burung as well as D. facchino in Sekopong. There are 74% among the sample of fishermen caught D. quadridens in those areas with an average number of 36 individuals and weight of 959 grams. While, 40% of fishermen caught D. facchino with an average number of 17 individuals and weight 152 grams.

  9. CRAB3: Establishing a new generation of services for distributed analysis at CMS

    International Nuclear Information System (INIS)

    Cinquilli, M; Spiga, D; Konstantinov, P; Mascheroni, M; Grandi, C; Hernàndez, J M; Riahi, H; Vaandering, E

    2012-01-01

    In CMS Computing the highest priorities for analysis tools are the improvement of the end users’ ability to produce and publish reliable samples and analysis results as well as a transition to a sustainable development and operations model. To achieve these goals CMS decided to incorporate analysis processing into the same framework as data and simulation processing. This strategy foresees that all workload tools (TierO, Tier1, production, analysis) share a common core with long term maintainability as well as the standardization of the operator interfaces. The re-engineered analysis workload manager, called CRAB3, makes use of newer technologies, such as RESTFul based web services and NoSQL Databases, aiming to increase the scalability and reliability of the system. As opposed to CRAB2, in CRAB3 all work is centrally injected and managed in a global queue. A pool of agents, which can be geographically distributed, consumes work from the central services serving the user tasks. The new architecture of CRAB substantially changes the deployment model and operations activities. In this paper we present the implementation of CRAB3, emphasizing how the new architecture improves the workflow automation and simplifies maintainability. In particular, we will highlight the impact of the new design on daily operations.

  10. CRAB3: Establishing a new generation of services for distributed analysis at CMS

    Science.gov (United States)

    Cinquilli, M.; Spiga, D.; Grandi, C.; Hernàndez, J. M.; Konstantinov, P.; Mascheroni, M.; Riahi, H.; Vaandering, E.

    2012-12-01

    In CMS Computing the highest priorities for analysis tools are the improvement of the end users’ ability to produce and publish reliable samples and analysis results as well as a transition to a sustainable development and operations model. To achieve these goals CMS decided to incorporate analysis processing into the same framework as data and simulation processing. This strategy foresees that all workload tools (TierO, Tier1, production, analysis) share a common core with long term maintainability as well as the standardization of the operator interfaces. The re-engineered analysis workload manager, called CRAB3, makes use of newer technologies, such as RESTFul based web services and NoSQL Databases, aiming to increase the scalability and reliability of the system. As opposed to CRAB2, in CRAB3 all work is centrally injected and managed in a global queue. A pool of agents, which can be geographically distributed, consumes work from the central services serving the user tasks. The new architecture of CRAB substantially changes the deployment model and operations activities. In this paper we present the implementation of CRAB3, emphasizing how the new architecture improves the workflow automation and simplifies maintainability. In particular, we will highlight the impact of the new design on daily operations.

  11. Artificial lights improve the catchability of snow crab (Chionoecetes opilio traps

    Directory of Open Access Journals (Sweden)

    Khanh Q. Nguyen

    2017-05-01

    Full Text Available This study investigated the behaviour and commercial catchability of snow crab (Chionoecetes opilio in response to different low-powered LED lights under laboratory and field conditions. We created a novel choice-experiment in a laboratory setting in which we investigated the behaviour of snow crab in response to coloured LED lights. The results showed that snow crab movement was dependent on light colour, with animals choosing to move toward blue and white lights, away from purple lights, and no detectable effect for green and red lights. We then conducted two field experiments to investigate the effect of the same LED lights on the catch rates of commercial traps during the 2016 snow crab fishery on the east coast of Newfoundland and Labrador. Results from the first field experiment showed that adding white and purple LED lights into baited traps significantly improved Catch Per Unit Effort (CPUE by 77% and 47% respectively. Results from the second field experiment showed that unbaited traps equipped with only LED lights (no bait, could also catch snow crab in comparable amounts to traditional baited traps, with soak time and depth explaining some of the variation in CPUE. Taken together, these experiments suggest that fishing enterprises can improve their catching performance and profitability by adding LED lights to their traps, or by using LED lights as a bait replacement.

  12. The Utilization of Blue Swimming Crab (Portunus pelagicus) Waste Product, Lemi, as a Food Flavor

    Science.gov (United States)

    Sasongko, A. Y.; Dewi, E. N.; Amalia, U.

    2018-01-01

    Lemi is a wasted product that resulted from the meating process of blue swim crab. One of the utilization of blue swim crab lemi is processed it into a food flavor. The aim of this research was to know the value of glutamic acid in blue swim crab lemi flavor with the addition of dextrin using different concentration and know the level of consumer preference of lemi flavor by using hedonic test. The research was using a Completely Randomized research Design (CRD) with a factor of 0%, 1%, 2%, and 3% dextrin concentration. The treatment that was tested was the additions of 0%, 1%, 2%, and 3% dextrin. The nonparametric data (panelist hedonic level) was analyzed by Kruskal-Wallis and further analysis using Mann-Whitney. The parametric data (glutamic acid content, protein content, moisture content, and solubility level) were analyzed by analysis of varians and further analysis using Honestly Significant Difference. The results showed that flavor with 1% dextrin addition has the highest hedonic score (7,07 swim crab lemi flavor. The flavor resulted from this experiment can be used as an alternative of blue swim crab lemi as processing waste so that it can optimalized any further.

  13. Flood Tide Transport of Blue Crab Postlarvae: Limitations in a Lagoonal Estuary

    Science.gov (United States)

    Cudaback, C.; Eggleston, D.

    2005-05-01

    Blue crabs, an important commercial species, spend much of their life in estuaries along the east coast. The larvae spawn at or near the ocean, but the juveniles mature in the lower salinity waters of the estuary. It is generally believed that blue crab postlarvae migrate into near surface waters on flood, possibly cued by increasing salinity, and return to the bottom on ebb. Over several tidal cycles, the postlarvae travel a significant distance up-estuary. This model applies quite well to Chesapeake Bay, which has a strong along-estuary salinity gradient and large tides, but may not apply as well to Pamlico Sound, where circulation and salinity are more wind-driven than tidal. A recently completed study (N. Reyns, PhD), indicates that postlarval blue crabs use flood tides and wind-driven currents to cross Pamlico Sound. This study was based on observations with good spatial coverage, but limited vertical and temporal resolution. We have recently completed a complementary study, sampling crab larvae around the clock at four depths at a single location. Preliminary results from the new study suggest that the crab postlarvae do swim all the way to the surface, on flood only, and that flood currents are strongest slightly below the surface. These observations suggest the utility of flood tide transport in this system. However, near bottom salinity does not seem to be driven by tides; at this point it is unclear what cue might trigger the vertical migration of the postlarvae.

  14. Ontogenetic scaling of the olfactory antennae and flicking behavior of the shore crab, Hemigrapsus oregonensis.

    Science.gov (United States)

    Waldrop, Lindsay D

    2013-07-01

    Malacostracan crustaceans such as crabs flick antennae with arrays of olfactory sensilla called aesthetascs through the water to sense odors. Flicking by crabs consists of a quick downstroke, in which aesthetascs are deflected laterally (splayed), and a slower, reversed return stroke, in which aesthetascs clump together. This motion causes water to be flushed within and then held in between aesthetascs to deliver odor molecules to olfactory receptors. Although this odor sampling method relies on a narrow range of speeds, sizes, and specific arrangements of aesthetascs, most crabs dramatically change these during ontogeny. In this study, the morphometrics of the aesthetascs, array, and antennae and the flicking kinematics of the Oregon shore crab, Hemigrapsus oregonensis (Decapoda: Brachyura), are examined to determine their scaling relationships during ontogeny. The morphometrics of the array and antennae increase more slowly than would be predicted by isometry. Juvenile crabs' aesthetascs splay relatively further apart than adults, likely due to changing material properties of aesthetasc cuticle during growth. These results suggest that disproportionate growth and altered aesthetasc splay during flicking will mediate the size changes due to growth that would otherwise lead to a loss of function.

  15. Infection of juvenile edible crabs, Cancer pagurus by a haplosporidian-like parasite.

    Science.gov (United States)

    Thrupp, Tara J; Lynch, Sharon A; Wootton, Emma C; Malham, Shelagh K; Vogan, Claire L; Culloty, Sarah C; Rowley, Andrew F

    2013-09-01

    This study aimed to examine the pathobiology of a haplosporidian-like infection in juvenile (pre-recruit) edible crabs (Cancer pagurus) from two locations in South West Wales, UK. Infected crabs showed no external symptoms of the disease but dissection revealed an infected and hypertrophic antennal gland. Histological examination showed extensive parasitisation of the antennal gland overlying the hepatopancreas. Heavily infected crabs also showed the presence of parasites with morphological similarities to Haplosporidia in the labyrinth of the antennal gland and in the gills. The spread of the infection from the antennal gland to the gills suggests that these parasites are released into the haemolymph. Attempts to characterise the haplosporidian-like organism using several primers previously shown to amplify members of the phylum Haplosporidia failed. The prevalence of infection in juvenile edible crabs varied throughout the sampling period of November 2011 to July 2012 with the lowest level of ca. 15% in November peaking at 70% in March. This parasite may represent a threat to the sustainability of edible crab fisheries in this region if the damage observed in the antennal gland and gills results in host mortality. The identification of these parasites as members of the phylum Haplosporidia based on morphology alone must be seen as tentative in the absence of sequence data. Copyright © 2013 Elsevier Inc. All rights reserved.

  16. Concurrent protein synthesis is required for in vivo chitin synthesis in postmolt blue crabs

    International Nuclear Information System (INIS)

    Horst, M.N.

    1990-01-01

    Chitin synthesis in crustaceans involves the deposition of a protein-polysaccharide complex at the apical surface of epithelial cells which secrete the cuticle or exoskeleton. The present study involves an examination of in vivo incorporation of radiolabeled amino acids and amino sugars into the cuticle of postmolt blue crabs, Callinectes sapidus. Rates of incorporation of both 3H leucine and 3H threonine were linear with respect to time of incubation. Incorporation of 3H threonine into the endocuticle was inhibited greater than 90% in the presence of the protein synthesis inhibitor, puromycin. Linear incorporation of 14C glucosamine into the cuticle was also demonstrated; a significant improvement of radiolabeling was achieved by using 14C-N-acetylglucosamine as the labeled precursor. Incorporation of 3H-N-acetylglucosamine into the cuticle of postmolt blue crabs was inhibited 89% by puromycin, indicating that concurrent protein synthesis is required for the deposition of chitin in the blue crab. Autoradiographic analysis of control vs. puromycin-treated crabs indicates that puromycin totally blocks labeling of the new endocuticle with 3H glucosamine. These results are consistent with the notion that crustacean chitin is synthesized as a protein-polysaccharide complex. Analysis of the postmolt and intermolt blue crab cuticle indicates that the exoskeleton contains about 60% protein and 40% chitin. The predominant amino acids are arginine, glutamic acid, alanine, aspartic acid, and threonine

  17. Cholesterol Effect on Survival and Development of Larval Mud Crab Scylla serrata

    Directory of Open Access Journals (Sweden)

    MUHAMMAD AGUS SUPRAYUDI

    2012-03-01

    Full Text Available The effect of cholesterol on the survival and development of larval mud crab Scylla serrata were examined by feeding larvae with Artemia enriched with different level of cholesterol. Artemia enriched with four stated levels of cholesterol i.e., 0, 5, 10, and 20 ul/l (Chol 0, 5, 10, and 20. All treatments were mixed with DHA70G at 25 ul/l. All the oil was adjusted to 100 ul/l by adding the oleic acid. Survival rate, intermolt period, and carapace width at the fisrt crab stage of mud crab larvae fed Chol 0, 5, and 10 were higher compared to that of Chol 20 (P < 0.05. We suggest that free sterol contained in Artemia at 1.37% was harmful to the growth performance of mud crab larvae. This study suggests that mud crab larvae required at least 0.61% cholesterol for maintaining good survival and development and therefore no need to enrich Artemia by cholesterol for the practical purpose.

  18. Synchro-Betatron Stop-Bands Due to a Single Crab Cavity

    Energy Technology Data Exchange (ETDEWEB)

    Chao, A

    2004-06-17

    We analyze the stop-band due to crab cavities for horizontal tunes that are either close to integers or close to half integers. The latter case is relevant for today's electron/positron colliders. We compare this stop-band to that created by dispersion in an accelerating cavity and show that a single typical crab cavity creates larger stop-bands than a typical dispersion at an accelerating cavity. We furthermore analyze whether it is beneficial to place the crab cavity at a position where the dispersion and its slope vanish. We find that this choice is worth while if the horizontal tune is close to a half integer, but not if it is close to an integer. Furthermore we find that stop-bands can be avoided when the horizontal tune is located at a favorable side of the integer or the half integer. While we are here concerned with the installation of a single crab cavity in a storage ring, we show that the stop-bands can be weakened, although not eliminated, significantly when two crab cavities per ring are chosen suitably.

  19. Genetic and morphological identification of some crabs from the Gulf of Suez, Northern Red Sea, Egypt

    Directory of Open Access Journals (Sweden)

    Eman M. Abbas

    2016-09-01

    Full Text Available Most crab species inhabiting the Red Sea have not been characterized morphologically and genetically. In the current work, five different crab species were collected from the northern part of the Egyptian Red Sea. They were morphologically identified through description of colors, dentations of the carapace and shapes of chelipeds and pereiopods. They were also genetically characterized by the partial sequencing of the barcode region in the mitochondrial cytochrome oxidase subunit I (COI gene, which is known to be hypervariable among different crab species. Morphological and genetic characterization identified the crab species as: Charybdis (Charybdis hellerii (A. Milne-Edwards, 1867, Charybdis (Charybdis natator (Herbst, 1794, Portunus (Portunus pelagicus (Linnaeus, 1758, Liocarcinus corrugatus (Pennant, 1777, and Atergatis roseus (Rüppell, 1830. This is the first record of L. corrugatus in the Egyptian Red Sea, despite being previously recorded in the Indian and Atlantic Ocean as well as in the Mediterranean Sea. DNA barcoding with precise morphological identification was effective in characterizing the crab species collected from the Egyptian Red Sea water.

  20. Use of Hyperspectral Imagery to Assess Cryptic Color Matching in Sargassum Associated Crabs.

    Directory of Open Access Journals (Sweden)

    Brandon J Russell

    Full Text Available Mats of the pelagic macroalgae Sargassum represent a complex environment for the study of marine camouflage at the air-sea interface. Endemic organisms have convergently evolved similar colors and patterns, but quantitative assessments of camouflage strategies are lacking. Here, spectral camouflage of two crab species (Portunus sayi and Planes minutus was assessed using hyperspectral imagery (HSI. Crabs matched Sargassum reflectance across blue and green wavelengths (400-550 nm and diverged at longer wavelengths. Maximum discrepancy was observed in the far-red (i.e., 675 nm where Chlorophyll a absorption occurred in Sargassum and not the crabs. In a quantum catch color model, both crabs showed effective color matching against blue/green sensitive dichromat fish, but were still discernible to tetrachromat bird predators that have visual sensitivity to far red wavelengths. The two species showed opposing trends in background matching with relation to body size. Variation in model parameters revealed that discrimination of crab and background was impacted by distance from the predator, and the ratio of cone cell types for bird predators. This is one of the first studies to detail background color matching in this unique, challenging ecosystem at the air-sea interface.

  1. Beam dynamics aspects of crab cavities in the CERN Large Hadron Collider

    CERN Document Server

    Sun, Y P; Barranco, J; Tomás, R; Weiler, T; Zimmermann, F; Calaga, R; Morita, A

    2009-01-01

    Modern colliders bring into collision a large number of bunches to achieve a high luminosity. The long-range beam-beam effects arising from parasitic encounters at such colliders are mitigated by introducing a crossing angle. Under these conditions, crab cavities (CC) can be used to restore effective head-on collisions and thereby to increase the geometric luminosity. Such crab cavities have been proposed for both linear and circular colliders. The crab cavities are rf cavities operated in a transverse dipole mode, which imparts on the beam particles a transverse kick that varies with the longitudinal position along the bunch. The use of crab cavities in the Large Hadron Collider (LHC) may not only raise the luminosity, but it could also complicate the beam dynamics, e.g., crab cavities might not only cancel synchrobetatron resonances excited by the crossing angle but they could also excite new ones, they could reduce the dynamic aperture for off-momentum particles, they could influence the aperture and orbit...

  2. Antibiotics in Crab Ponds of Lake Guchenghu Basin, China: Occurrence, Temporal Variations, and Ecological Risks

    Directory of Open Access Journals (Sweden)

    Wenxia Wang

    2018-03-01

    Full Text Available Antibiotics are widely used in aquaculture, however, this often results in undesirable ecological effects. To evaluate the occurrence, temporal variations, and ecological risk of antibiotics in five crab ponds of Lake Guchenghu Basin, China, 44 antibiotics from nine classes were analyzed by rapid resolution liquid chromatography-tandem mass spectrometry (RRLC-MS/MS. Twelve antibiotics belonging to six classes were detected in the aqueous phase of five crab ponds, among which sulfonamides and macrolides were the predominant classes, and six compounds (sulfamonomethoxine, sulfadiazine, trimethoprim, erythromycin-H2O, monensin, and florfenicol were frequently detected at high concentrations. In general, the antibiotic levels varied between different crab ponds, with the average concentrations ranging from 122 to 1440 ng/L. The antibiotic concentrations in crab ponds exhibited obvious seasonal variations, with the highest concentration and detection frequency detected in summer. Multivariate analysis showed that antibiotic concentrations were significantly correlated with environmental variables, such as total organic carbon, phosphate, ammonia nitrogen, and pH. Sulfadiazine, clarithromycin, erythromycin-H2O, and ciprofloxacin posed a high risk to algae, while the mixture of antibiotics could pose a high risk to aquatic organisms in the crab ponds. Overall, the usage of antibiotics in farming ponds should be comprehensively investigated and controlled to preserve a healthy aquaculture ecosystem.

  3. Compact 400-Mhz Half-Wave Spoke Resonator Crab Cavity for the LHC Update

    International Nuclear Information System (INIS)

    Li, Zenghai

    2010-01-01

    Crab cavities are proposed for the LHC upgrade to improve the luminosity. There are two possible crab cavity installations for the LHC upgrade: the global scheme at Interaction Region (IR) 4 where the beam-beam separation is about 420-mm, and the local scheme at the IR5 where the beam-beam separation is only 194-mm. One of the design requirements as the result of a recent LHC-Crab cavity workshop is to develop a 400-MHz cavity design that can be utilized for either the global or local schemes at IR4 or IR5. Such a design would offer more flexibility for the final upgrade installation, as the final crabbing scheme is yet to be determined, and save R and D cost. The cavity size of such a design, however, is limited by the beam-beam separation at IR5 which can only accommodate a cavity with a horizontal size of about 145-mm, which is a design challenge for a 400-MHz cavity. To meet the new design requirements, we have developed a compact 400-MHz half-wave spoke resonator (HWSR) crab cavity that can fit into the tight spaces available at either IR4 or IR5. In this paper, we present the optimization of the HWSR cavity shape and the design of HOM, LOM, and SOM couplers for wakefield damping.

  4. CRAB3: Establishing a new generation of services for distributed analysis at CMS

    Energy Technology Data Exchange (ETDEWEB)

    Cinquilli, M. [CERN; Spiga, D. [CERN; Grandi, C. [INFN, Bologna; Hernandez, J. M. [Madrid, CIEMAT; Konstantinov, P. [CERN; Mascheroni, M. [CERN; Riahi, H. [INFN, Perugia; Vaandering, E. [Fermilab

    2012-01-01

    In CMS Computing the highest priorities for analysis tools are the improvement of the end users ability to produce and publish reliable samples and analysis results as well as a transition to a sustainable development and operations model. To achieve these goals CMS decided to incorporate analysis processing into the same framework as data and simulation processing. This strategy foresees that all workload tools (TierO, Tier1, production, analysis) share a common core with long term maintainability as well as the standardization of the operator interfaces. The re-engineered analysis workload manager, called CRAB3, makes use of newer technologies, such as RESTFul based web services and NoSQL Databases, aiming to increase the scalability and reliability of the system. As opposed to CRAB2, in CRAB3 all work is centrally injected and managed in a global queue. A pool of agents, which can be geographically distributed, consumes work from the central services serving the user tasks. The new architecture of CRAB substantially changes the deployment model and operations activities. In this paper we present the implementation of CRAB3, emphasizing how the new architecture improves the workflow automation and simplifies maintainability. In particular, we will highlight the impact of the new design on daily operations.

  5. A case of leucism in the burrowing owl Athene cunicularia (Aves: Strigiformes with confirmation of species identity using cytogenetic analysis

    Directory of Open Access Journals (Sweden)

    Denise M Nogueira

    2011-02-01

    Full Text Available Leucism is an inherited disorder, characterized by the lack of pigments in part or all of the body, normal coloration of the eyes and, in birds, in naked parts such as the bill and legs. This kind of disorder is sometimes erroneously designated as albinism or partial albinism. In this study, we present a case of leucism in a wild owl. The studied individual presented completely white plumage, light-yellow coloration of legs and bill and normal coloration of eyes. According to morphological features, this owl is a specimen of burrowing owl, Athene cunicularia (Molina, 1782. To confirm the species identity, we used cytogenetic analyses for karyotypic determination, comparing it to the previously described one in the literature. We also studied a captive female of A. cunicularia to complement the species karyotype, which was described in the literature based only on a single male. The karyotype of the leucistic owl individual was compatible with the previously published one for A. cunicularia, confirming the bird was a male specimen. Cytogenetic analysis of the captive female showed that the W sex chromosome is metacentric and comparable to the seventh pair in size. This is the first description of a case of leucism in A. cunicularia for South America. Long-term studies are needed in the Neotropical region to evaluate survival and breeding success in leucistic birds.

  6. CHINESE MITTEN CRABS (ERIOCHEIR SINENSIS) IN THE ST. LAWRENCE RIVER (CANADA): NEW RECORDS AND RISK OF INVASION

    Science.gov (United States)

    The Chinese mitten crab, Eriocheir sinensis, is an internationally renowned aquatic invader. Native to China and North/South Korea, this catadromous crab has successfully invaded several rivers and estuaries in eleven countries in Western Europe as well as the San Francisco Bay ...

  7. 75 FR 27219 - Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab Fisheries; 2010 Atlantic...

    Science.gov (United States)

    2010-05-14

    .... Whereas a limited market has been responsible for the shortfall in landings compared to the target TAC... final specifications for the 2010 Atlantic deep- sea red crab fishery, including a target total... specify the target TAC and other management measures in order to manage the red crab resource for fishing...

  8. 78 FR 17341 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Science.gov (United States)

    2013-03-21

    ... Purchased. contracting custom processing must report. Raw pounds by crab fishery. Product and processes by... purchased (raw Purchased. pounds) by crab fishery. Custom processing services purchased (product and process... greatest information value to the management decision making process. The EDR is required to be submitted...

  9. Increase in density of genetically diverse invasive Asian shore crab (Hemigrapsus sanguineus) populations in the Gulf of Maine.

    Science.gov (United States)

    Lord, Joshua P; Williams, Larissa M

    2017-04-01

    Hemigrapsus sanguineus , the Asian shore crab, has rapidly replaced Carcinus maenas , the green crab, as the most abundant crab on rocky shores in the northwest Atlantic since its introduction to the United States (USA) in 1988. The northern edge of this progressing invasion is the Gulf of Maine, where Asian shore crabs are only abundant in the south. We compared H. sanguineus population densities to those from published 2005 surveys and quantified genetic variation using the cytochrome c oxidase subunit I gene. We found that the range of H. sanguineus had extended northward since 2005, that population density had increased substantially (at least 10-fold at all sites), and that Asian shore crabs had become the dominant intertidal crab species in New Hampshire and southern Maine. Despite the significant increase in population density of H. sanguineus , populations only increased by a factor of 14 in Maine compared to 70 in southern New England, possibly due to cooler temperatures in the Gulf of Maine. Genetically, populations were predominantly composed of a single haplotype of Japanese, Korean, or Taiwanese origin, although an additional seven haplotypes were found. Six of these haplotypes were of Asian origin, while two are newly described. Large increases in population sizes of genetically diverse individuals in Maine will likely have a large ecological impact, causing a reduction in populations of mussels, barnacles, snails, and other crabs, similar to what has occurred at southern sites with large populations of this invasive crab species.

  10. 78 FR 28523 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Science.gov (United States)

    2013-05-15

    ...; Bering Sea and Aleutian Islands Crab Rationalization Program AGENCY: National Marine Fisheries Service... Rationalization Program (CR Program) by establishing a process whereby holders of regionally designated individual... scope of this action. Comment 9: One comment generally supported the Crab Rationalization Program...

  11. 75 FR 43147 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Science.gov (United States)

    2010-07-23

    ... of a 2.67-percent fee for cost recovery under the Bering Sea and Aleutian Islands Crab... for the 2010/2011 crab fishing year so they can calculate the required payment for cost recovery fees...-Stevens Act). The Program includes a cost recovery provision to collect fees to recover the actual costs...

  12. 78 FR 46577 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Science.gov (United States)

    2013-08-01

    ... of a 0.69-percent fee for cost recovery under the Bering Sea and Aleutian Islands Crab... for the 2013/2014 crab fishing year so they can calculate the required payment for cost recovery fees... Program includes a cost recovery provision to collect fees to recover the actual costs directly related to...

  13. 76 FR 43658 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Science.gov (United States)

    2011-07-21

    ... of a 1.23-percent fee for cost recovery under the Bering Sea and Aleutian Islands Crab... for the 2011/2012 crab fishing year so they can calculate the required payment for cost recovery fees...-Stevens Act). The Program includes a cost recovery provision to collect fees to recover the actual costs...

  14. Mercury burdens in Chinese mitten crabs (Eriocheir sinensis) in three tributaries of southern San Francisco Bay, California, USA

    Energy Technology Data Exchange (ETDEWEB)

    Hui, Clifford A. [US Geological Survey, 7801 Folsom Blvd, Suite 101, Sacramento, CA 95826 (United States)]. E-mail: bioinvestigations@sbcglobal.net; Rudnick, Deborah [Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720 (United States); Williams, Erin [US Fish and Wildlife Service, 4001 N. Wilson Way, Stockton, CA 95205 (United States)

    2005-02-01

    Chinese mitten crabs (Eriocheir sinensis), endemic to Asia, were first reported in the San Francisco Bay in 1992. They are now established in nearly all San Francisco Bay tributaries. These crabs accumulate more metals, such as mercury, than crustaceans living in the water column. Because their predators include fish, birds, mammals and humans, their mercury burdens have an exceptional potential to impact the ecosystem and public health. We sought to elucidate the potential threat of mitten crab mercury burdens in three adjacent streams in southern San Francisco Bay, one of which is known to be contaminated with mercury. Mitten crabs had hepatopancreas concentrations of total mercury and methylmercury that did not differ among streams. The maximum burden we measured was below the action level of 1 ppm recommended by the USEPA. Hepatopancreas concentrations of methylmercury declined with increasing crab size, suggesting a mechanism for mercury excretion and that predators might reduce mercury exposure if they select larger crabs. Because mercury may be heterogeneously distributed among tissues, estimation of the impacts of crab mercury burdens on the environment requires more data on the feeding preferences of predators. - Hepatopancreas concentrations of mercury decline with crab size, which may have important consequences for bio-magnification in food webs.

  15. 76 FR 60379 - Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab; Amendment 3

    Science.gov (United States)

    2011-09-29

    .... 100903433-1531-02] RIN 0648-BA22 Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab... approved in Amendment 3 to the Atlantic Deep-Sea Red Crab Fishery Management Plan (FMP). The New England... ABC control rule.'' The NS1 guidelines further state that ``ABC may not exceed OFL,'' and that ``the...

  16. Mercury burdens in Chinese mitten crabs (Eriocheir sinensis) in three tributaries of southern San Francisco Bay, California, USA

    International Nuclear Information System (INIS)

    Hui, Clifford A.; Rudnick, Deborah; Williams, Erin

    2005-01-01

    Chinese mitten crabs (Eriocheir sinensis), endemic to Asia, were first reported in the San Francisco Bay in 1992. They are now established in nearly all San Francisco Bay tributaries. These crabs accumulate more metals, such as mercury, than crustaceans living in the water column. Because their predators include fish, birds, mammals and humans, their mercury burdens have an exceptional potential to impact the ecosystem and public health. We sought to elucidate the potential threat of mitten crab mercury burdens in three adjacent streams in southern San Francisco Bay, one of which is known to be contaminated with mercury. Mitten crabs had hepatopancreas concentrations of total mercury and methylmercury that did not differ among streams. The maximum burden we measured was below the action level of 1 ppm recommended by the USEPA. Hepatopancreas concentrations of methylmercury declined with increasing crab size, suggesting a mechanism for mercury excretion and that predators might reduce mercury exposure if they select larger crabs. Because mercury may be heterogeneously distributed among tissues, estimation of the impacts of crab mercury burdens on the environment requires more data on the feeding preferences of predators. - Hepatopancreas concentrations of mercury decline with crab size, which may have important consequences for bio-magnification in food webs

  17. Elemental compositions of crab and snail shells from the Kueishantao hydrothermal field in the southwestern Okinawa Trough

    Science.gov (United States)

    Zeng, Zhigang; Ma, Yao; Wang, Xiaoyuan; Chen, Chen-Tung Arthur; Yin, Xuebo; Zhang, Suping; Zhang, Junlong; Jiang, Wei

    2018-04-01

    To reveal differences in the behavior of benthic vent animals, and the sources and sinks of biogeochemical and fluid circulations, it is necessary to constrain the chemical characteristics of benthic animals from seafloor hydrothermal fields. We measured the abundances of 27 elements in shells of the crab Xenograpsus testudinatus and the snail Anachis sp., collected from the Kueishantao hydrothermal field (KHF) in the southwestern Okinawa Trough, with the aim of improving our understanding of the compositional variations between individual vent organisms, and the sources of the rare earth elements (REEs) in their shells. The Mn, Hg, and K concentrations in the male X. testudinatus shells are found to be higher than those in female crab shells, whereas the reverse is true for the accumulation of B, implying that the accumulation of K, Mn, Hg, and B in the crab shells is influenced by sex. This is inferred to be a result of the asynchronous molting of the male and female crab shells. Snail shells are found to have higher Ca, Al, Fe, Ni, and Co concentrations than crab shells. This may be attributed to different metal accumulation times. The majority of the light rare earth element (LREE) distribution patterns in the crab and snail shells are similar to those of Kueishantao vent fluids, with the crab and snail shells also exhibiting LREE enrichment, implying that the LREEs contained in crab and snail shells in the KHF are derived from vent fluids.

  18. Modeling radio circular polarization in the Crab nebula

    Science.gov (United States)

    Bucciantini, N.; Olmi, B.

    2018-03-01

    In this paper, we present, for the first time, simulated maps of the circularly polarized synchrotron emission from the Crab nebula, using multidimensional state of the art models for the magnetic field geometry. Synchrotron emission is the signature of non-thermal emitting particles, typical of many high-energy astrophysical sources, both Galactic and extragalactic ones. Its spectral and polarization properties allow us to infer key information on the particles distribution function and magnetic field geometry. In recent years, our understanding of pulsar wind nebulae has improved substantially thanks to a combination of observations and numerical models. A robust detection or non-detection of circular polarization will enable us to discriminate between an electron-proton plasma and a pair plasma, clarifying once for all the origin of the radio emitting particles, setting strong constraints on the pair production in pulsar magnetosphere, and the role of turbulence in the nebula. Previous attempts at measuring the circular polarization have only provided upper limits, but the lack of accurate estimates, based on reliable models, makes their interpretation ambiguous. We show here that those results are above the expected values, and that current polarimetric techniques are not robust enough for conclusive result, suggesting that improvements in construction and calibration of next generation radio facilities are necessary to achieve the desired sensitivity.

  19. THE CRAB PULSAR AT CENTIMETER WAVELENGTHS. II. SINGLE PULSES

    Energy Technology Data Exchange (ETDEWEB)

    Hankins, T. H.; Eilek, J. A. [Physics Department, New Mexico Tech, Socorro, NM 87801 (United States); Jones, G., E-mail: thankins@aoc.nrao.edu [Columbia University, New York, NY 10027 (United States)

    2016-12-10

    We have carried out new, high-frequency, high-time-resolution observations of the Crab pulsar. Combining these with our previous data, we characterize bright single pulses associated with the Main Pulse, both the Low-Frequency and High-Frequency Interpulses, and the two  High-Frequency Components. Our data include observations at frequencies ranging from 1 to 43 GHz with time resolutions down to a fraction of a nanosecond. We find that at least two types of emission physics are operating in this pulsar. Both Main Pulses and Low-Frequency Interpulses, up to ∼10 GHz, are characterized by nanoshot emission—overlapping clumps of narrowband nanoshots, each with its own polarization signature. High-Frequency Interpulses, between 5 and 30 GHz, are characterized by spectral band emission—linearly polarized emission containing ∼30 proportionately spaced spectral bands. We cannot say whether the longer-duration High-Frequency Components pulses are due to a scattering process, or if they come from yet another type of emission physics.

  20. The crabs that live where hot and cold collide.

    Science.gov (United States)

    Thurber, Andrew R

    2015-07-01

    The distribution of Kiwa tyleri with the large male individual in the high-temperature flow (right hand side - fluid flow indicated by shimmering water) and the mixed sex assemblage (left). Note the heavy coat of epibiotic bacteria (grey colouring) on the individual in the hottest section of the vent, as expected from being closest to the sulphide needed to sustain the epibiotic bacteria that this species harvests for its food. Image courtesy of Dr. L. Marsh (Credit: NERC ChEsSo Consortium). In Focus: Marsh, L., Copley, J.T., Tyler, P.A. & Thatje, S. (2015) In hot and cold water: differential life-history traits are key to success in contrasting thermal deep-sea environments. Journal of Animal Ecology, 84, 898-913. Southern Ocean hydrothermal vents juxtapose two extremes - intense food-poor cold and scalding food-rich oases. At these vents, Marsh et al. (2015) found a community of Kiwa (Yeti) crabs that separated themselves along this gradient with the largest males sitting in hot, food-rich waters, while smaller males and females co-occur in an intermediate zone of warmth. However, as their eggs start to develop, females embark away from the vent to the food-poor yet stable cold of the Southern Ocean. This species has found an intriguing way to balance foraging risk and population persistence at the interface of hot and cold. © 2015 The Author. Journal of Animal Ecology © 2015 British Ecological Society.

  1. Estuarine retention of larvae of the crab Rhithropanopeus harrisii

    Science.gov (United States)

    Cronin, Thomas W.

    1982-08-01

    Larvae of estuarine organisms continually face possible export from the parent estuary. Retention of larvae of the estuarine crab Rhithropanopeus harrisii was investigated in the upper Newport River estuary, North Carolina. All of the developmental stages occurred in the same area of the estuary with similar horizontal distributions, and the concentrations of intermediate and late stages were not greatly reduced from those of the first larval stage. This was strong evidence for the continuous retention of larvae in the upper estuary. To determine mechanisms by which retention might be effected, field studies of the vertical distributions and migrations of these larvae were made. The four zoeal stages had similar but complex vertical migration patterns, which varied from study to study. These migrations centered on the depth of no net flow, reducing longitudinal transport during development. Cross-spectral analysis of the larval migrations and the environmental cycles of light, salinity and current speed revealed that each of these external cycles affected larval depth. Megalopae of R. harrisii also migrated vertically, but they were present in much lower concentrations than the zoeal stages, an indication of a change to benthic existence in this final larval form.

  2. HOM/LOM Coupler Study for the ILC Crab Cavity

    International Nuclear Information System (INIS)

    Xiao, L.; Li, Z.; Ko, K.

    2007-01-01

    The FNAL 9-cell 3.9GHz deflecting mode cavity designed for the CKM experiment was chosen as the baseline design for the ILC BDS crab cavity. The full 9-cell CKM cavity including the coupler end-groups was simulated using the parallel eigensolver Omega3P and scattering parameter solver S3P. It was found that both the notch filters for the HOM/LOM couplers are very sensitive to the notch gap, which is about 1.6MHz/micron and is more than 10 times more sensitive than the TTF cavity. It was also found in the simulation that the unwanted vertical π-mode (SOM) is strongly coupled to the horizontal 7π/9 mode which causes x-y coupling and reduces the effectiveness of the SOM damping. To meet the ILC requirements, the HOM/LOM couplers are redesigned to address these issues. With the new designs, the damping of the HOM/LOM modes is improved. The sensitivity of the notch filter for the HOM coupler is reduced by one order of magnitude. The notch filter for the LOM coupler is eliminated in the new design which significantly simplifies the geometry. In this paper, we will present the simulation results of the original CKM cavity and the progresses on the HOM/LOM coupler re-design and optimization

  3. Multiple origins of subsociality in crab spiders (Thomisidae).

    Science.gov (United States)

    Ruch, Jasmin; Riehl, Torben; May-Collado, Laura J; Agnarsson, Ingi

    2015-01-01

    Determining factors that facilitate the transition from a solitary to a social lifestyle is a major challenge in evolutionary biology, especially in taxa that are usually aggressive towards conspecifics. Most spiders live solitarily and few species are known to be social. Nevertheless, sociality has evolved multiple times across several families and nearly all studied social lineages have originated from a periodically social (subsocial) ancestor. Group-living crab spiders (Thomisidae) are exclusively found in Australia and differ from most other social spiders because they lack a communal capture web. Three of the group-living species were placed in the genus Diaea and another in the genus Xysticus. Most Australian thomisids are, however, difficult to identify as most descriptions are old and of poor quality, and the genera Diaea and Xysticus may not correspond to monophyletic groups. Here, we clarify the phylogenetic relationships of the four group-living Australian thomisids and conclude that amongst these subsociality has evolved two to three times independently. The subsocial Xysticus bimaculatus is not closely related to any of the social Diaea and an independent origin of subsociality is likely in this case. The presented data indicates that within Diaea two origins of subsociality are possible. Our results help to understand the evolution of sociality in thomisids and support the hypothesis that permanent sociality in spiders has evolved multiple times relatively recently from subsocial ancestors. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. Changes in the selection differential exerted on a marine snail during the ontogeny of a predatory shore crab.

    Science.gov (United States)

    Pakes, D; Boulding, E G

    2010-08-01

    Empirical estimates of selection gradients caused by predators are common, yet no one has quantified how these estimates vary with predator ontogeny. We used logistic regression to investigate how selection on gastropod shell thickness changed with predator size. Only small and medium purple shore crabs (Hemigrapsus nudus) exerted a linear selection gradient for increased shell-thickness within a single population of the intertidal snail (Littorina subrotundata). The shape of the fitness function for shell thickness was confirmed to be linear for small and medium crabs but was humped for large male crabs, suggesting no directional selection. A second experiment using two prey species to amplify shell thickness differences established that the selection differential on adult snails decreased linearly as crab size increased. We observed differences in size distribution and sex ratios among three natural shore crab populations that may cause spatial and temporal variation in predator-mediated selection on local snail populations.

  5. The Amino Acid Composition of Blue Swimming Crab (Portunus Segnis, Forskal, 1775 from The North Eastern Mediterranean Sea of Turkey

    Directory of Open Access Journals (Sweden)

    Engin Artar

    2018-04-01

    Full Text Available This study was carried out to detect the content of amino acid in female and male specimens of blue swimming crab (Portunus segnis obtained from (including 12 male crab and also 12 female crab North Eastern Mediterranean Sea, Turkey. The protein was identified as 17.63% and 18.13% for female and male crab respevtively. Totally 9 essential amino acids were recorded in the present study. Lysine and leucine constituted the highest essential amino acid (EAA concentrations in P. segnis. This species was found to be in good score in terms of the level of EAA and the EAA/Non-EAA ratios when compared with other economical crab species.

  6. Reproductive biology of the Suez Canal spider crab Schizophrys aspera (H. Milne Edwards, 1834: Crustacea: Brachyura: Majidae).

    Science.gov (United States)

    El-Serehy, Hamed A; Al-Rasheid, Khaled A; Ibrahim, Nesreen K; Al-Misned, Fahad A

    2015-11-01

    A reproductive biology study of the spider crab Schizophrys aspera (H. Milne Edwards, 1834) was conducted in the Suez Canal from July 2012 to June 2013. The annual sex ratio (Male:Female) of S. aspera was female biased with values of 1:1.25. Out of the four ovarian development stages of this crab, two stages were observed in the Suez Canal throughout the whole year. The ovigerous crab's carapace width varied from 28 to 52 mm. This crab species can spawn during most of the year in the canal water, with a peak during late spring and early winter. The fecundity of ovigerous females ranged between 2349 and 13600 eggs with a mean of 5494 ± 1486 eggs. Female crabs that reached sexual maturity exhibited a minimum carapace width varying between 22 and 46 mm, and fifty percentage of all ovigerous females showed a carapace width of 36 mm.

  7. Clash of the crabs: Interspecific, inter-cohort competition between the native European green crab, Carcinus maenas and the exotic brush clawed crab Hemigrapsus takanoi on artificial oyster reefs

    Science.gov (United States)

    van den Brink, Anneke; Hutting, Samara

    2017-10-01

    Interaction between cohorts was investigated with juveniles of the native crab Carcinus maenas and adults of the exotic crab Hemigrapsus takanoi on artificial, intertidal oyster reefs. The reefs are occupied by C. maenas seasonally as a nursery habitat and consistently by adult H. takanoi. There was a distinct decrease in abundance of C. maenas of the same carapace width as most adult H. takanoi, suggesting competition at this size was occurring. Laboratory experiments indicated that H. takanoi was a more aggressive competitor for food and, with consistently high abundance on the reefs, may result in some exclusion of C. maenas from their nursery habitat. While total exclusion of C. maenas on the oyster reefs is unlikely, cohabitation may result in reduced population size or increased use of alternative nursery habitats.

  8. Scaled laboratory experiments explain the kink behaviour of the Crab Nebula jet.

    Science.gov (United States)

    Li, C K; Tzeferacos, P; Lamb, D; Gregori, G; Norreys, P A; Rosenberg, M J; Follett, R K; Froula, D H; Koenig, M; Seguin, F H; Frenje, J A; Rinderknecht, H G; Sio, H; Zylstra, A B; Petrasso, R D; Amendt, P A; Park, H S; Remington, B A; Ryutov, D D; Wilks, S C; Betti, R; Frank, A; Hu, S X; Sangster, T C; Hartigan, P; Drake, R P; Kuranz, C C; Lebedev, S V; Woolsey, N C

    2016-10-07

    The remarkable discovery by the Chandra X-ray observatory that the Crab nebula's jet periodically changes direction provides a challenge to our understanding of astrophysical jet dynamics. It has been suggested that this phenomenon may be the consequence of magnetic fields and magnetohydrodynamic instabilities, but experimental demonstration in a controlled laboratory environment has remained elusive. Here we report experiments that use high-power lasers to create a plasma jet that can be directly compared with the Crab jet through well-defined physical scaling laws. The jet generates its own embedded toroidal magnetic fields; as it moves, plasma instabilities result in multiple deflections of the propagation direction, mimicking the kink behaviour of the Crab jet. The experiment is modelled with three-dimensional numerical simulations that show exactly how the instability develops and results in changes of direction of the jet.

  9. Chaetotaxy and setal diversity of grooming legs in species of porcelain crabs (Crustacea: Anomura: Porcellanidae

    Directory of Open Access Journals (Sweden)

    Luciane Augusto de Azevedo Ferreira

    2018-03-01

    Full Text Available Abstract The morphology of the fifth pereiopods was studied under scanning electron microscopy in ten species of porcelain crabs for chaetotaxy and setal diversity, namelly Megalobrachium pacificum, Megalobrachium roseum, Pachycheles grossimanus, Petrolisthes armatus, Petrolisthes tuberculatus, Pisidia brasiliensis, Pisidia longicornis, Polyonyx gibbesi, Porcellana platycheles and Porcellana sayana. Six setal types were identified: simple, pappose, sickle-shaped serrate, straight serrate, club-shaped and tooth-like cuspidate. Porcelain crabs can differ in the fifth pereiopod setal morphology, chaetotaxy and setal density, even among species within the same genus. The absence of sexual dimorphism of the grooming legs in porcelain crabs suggests that grooming eggs requires no particular grooming apparatus in females and that male and female are equal in grooming efficiency.

  10. Spectral analysis of the Crab Pulsar and Nebula with the Fermi Large Area Telescope

    International Nuclear Information System (INIS)

    Loparco, F.

    2011-01-01

    The Crab Pulsar is a relatively young neutron star. The Pulsar is the central star in the Crab Nebula, a remnant of the supernova SN 1054, which was observed on Earth in the year 1054. The Crab Pulsar has been extensively observed in the gamma-ray energy band by the Large Area Telescope (LAT), the main instrument onboard the Fermi gamma-ray space telescope, during its first months of data taking. The LAT data have been used to reconstruct the fluxes and the energy spectra of the pulsed gamma-ray component and of the gamma-rays from the Nebula. The results on the pulsed component are in good agreement with the previous measurement from EGRET, while the results on the Nebula are consistent with the observations from Earth based telescopes.

  11. [Spectral sensitivity and visual pigments of the coastal crab Hemigrapsus sanguineus].

    Science.gov (United States)

    Shukoliukov, S A; Zak, P P; Kalamkarov, G R; Kalishevich, O O; Ostrovskiĭ, M A

    1980-01-01

    It has been shown that the compound eye of the coastal crab has one photosensitive pigment rhodopsin and screening pigments, black and orange one. The orange pigment has lambda max = 480 nm, rhodopsin in digitonin is stable towards hydroxylamin action, has lambda max = 490-495 nm and after bleaching is transformed into free retinene and opsin. The pigments with lambda max = 430 and 475 nm of the receptor part of the eye are also solubilized. These pigments are not photosensitive but they dissociate under the effect of hydroxylamine. The curye of spectral sensitivity of the coastal crab has the basic maximum at approximately 525 nm and the additional one at 450 nm, which seems to be provided by a combination of the visual pigment--rhodopsin (lambda max 500 nm) with a carotinoid filter (lambda max 480-490). Specific features of the visual system of coastal crab are discussed.

  12. Intraspecific shape variation in horseshoe crabs: the importance of sexual and natural selection for local adaptation

    DEFF Research Database (Denmark)

    Faurby, Søren; Nielsen, Kasper Sauer Kollerup; Bussarawit, Somchai

    2011-01-01

    . Differences in shape variation between sexes were tested with F-tests, which showed lower intrapopulation morphometric variation in males than females. These results indicate a lower degree of local adaptation on body shape in C. rotundicauda and T. gigas than in L. polyphemus and a lower degree of local......A morphometric analysis of the body shape of three species of horseshoe crabs was undertaken in order to infer the importance of natural and sexual selection. It was expected that natural selection would be most intense, leading to highest regional differentiation, in the American species Limulus...... polyphemus, which has the largest climatic differences between different populations. Local adaptation driven by sexual selection was expected in males but not females because horseshoe crab mating behaviour leads to competition between males, but not between females. Three hundred fifty-nine horseshoe crabs...

  13. Taxonomic confirmation of mud crab species (genus Scylla) in Bangladesh by nuclear and mitochondrial DNA markers.

    Science.gov (United States)

    Sarower, Mohammed Golam; Shahriar, Sheik Istiak Md; Nakamura, Hiromasa; Rouf, Muhammad Abdur; Okada, Shigeru

    2017-11-01

    Taxonomy of mud crabs genus Scylla has been misidentified for several years due to their high morphological plasticity. Several reports concerning mud crab have been published with misleading identification in Bangladesh. In this study, partial fragments of nuclear and mitochondrial DNA of Scylla species obtained from four locations along the Bangladesh coast were used to resolve taxonomical ambiguity of mud crab species. A single PCR product from the nuclear first internal transcribed spacer (ITS-1) marker and phylogenetic trees constructed based on 16S rDNA sequences indicated that all Scylla species obtained in this study were S. olivacea. Both molecular data and morphological characters revealed that S. olivacea is the only major species in Bangladesh coastal waters. Further, the 16S rDNA haplotypes significantly differed with known S. serrata by 33%. From this study it is clear that 'S. serrata' commonly reported from Bangladesh should be S. olivacea.

  14. Burying behaviour of two sympatric crab species: Cancer magister and Cancer productus

    Directory of Open Access Journals (Sweden)

    Iain J. McGaw

    2005-09-01

    Full Text Available The mechanics and emergence patterns associated with burying behaviour were investigated in the Dungeness crab, Cancer magister, and the red rock crab, Cancer productus. Cancer magister used both the legs and chelae to excavate the sand, whereas Cancer productus used the legs to pull and push itself down into the sediment only using the chelae in a final push beneath the sediment. Several individuals of each species remained buried for over 50 h, which was accomplished by alterations in ventilatory physiology. More commonly, both species exhibited an endogenous rhythm of circadian periodicity, with peak periods of emergence from the sand occurring during nocturnal high tides. Although burial may act as a means of predator evasion and to ambush prey, it appears the primary reason may be to conserve energy. These two species of crabs often occur sympatrically; the difference in behaviours is closely related to previously reported differences in physiological mechanisms between the two species when buried.

  15. Biological studies on the blue crab Portunus pelagicus and its parasitic infection in Kuwaiti waters.

    Science.gov (United States)

    Al-Behbehani, Bahija E

    2007-04-01

    The study investigated the parasites of symbiotic fauna of the blue crab, Portunus pelagicus and the environmental factors, which was lacking in Kuwait. P. pelagicus feeding habits was studied by examination of the digestive tract. The foregut (stomach) contents of 250 crabs (110 male & 140 female) collected from fish-market, Souq-Sharq, Edelyia capital governorate were investigated. A barnacle, Balanus sp. and staked barnacle Octolasmis sp. (Crustacea: Cirripedia) were found strongly firmly to the carapace, appendages and gills of 30% male crabs and 27% female ones. Endoparasites included unidentified immature trematode stages and nematode larvae in the muscular tissues of both sexes. The main food recovered included molluscs, crustaceans, fish bones and unidentified food materials. The results were reported, photographed and critically discussed.

  16. Near Infrared Activity Close to the Crab Pulsar Correlated with Giant Gamma-ray Flares

    Science.gov (United States)

    Rudy, Alexander R.; Max, Claire E.; Weisskopf, Martin C.

    2014-01-01

    We describe activity observed in the near-infrared correlated with a giant gamma-ray flare in the Crab Pulsar. The Crab Pulsar has been observed by the Fermi and AGILE satellites to flare for a period of 3 to 7 days, once every 1-1.5 years, increasing in brightness by a factor of 3-10 between 100MeV and 1GeV. We used Keck NIRC2 laser guide star adaptive optics imaging to observe the Crab Pulsar and environs before and during the March 2013 flare. We discuss the evidence for the knot as the location of the flares, and the theoretical implications of these observations. Ongoing target-of-opportunity programs hope to confirm this correlation for future flares.

  17. Analysis and control of wakefields in X-band crab cavities for Compact Linear Collider

    Energy Technology Data Exchange (ETDEWEB)

    Ambattu, P.K., E-mail: praveen-kumar.ambattu@stfc.ac.uk [Cockcroft Institute, Warrington WA4 4AD (United Kingdom); Lancaster University, Lancaster LA1 4 YW (United Kingdom); Burt, G. [Cockcroft Institute, Warrington WA4 4AD (United Kingdom); Lancaster University, Lancaster LA1 4 YW (United Kingdom); Khan, V.F.; Jones, R.M. [Cockcroft Institute, Warrington WA4 4AD (United Kingdom); University of Manchester, Manchester M13 9PL (United Kingdom); Dexter, A. [Cockcroft Institute, Warrington WA4 4AD (United Kingdom); Lancaster University, Lancaster LA1 4 YW (United Kingdom); Dolgashev, V. [SLAC, Menlo Park, CA 94025 (United States)

    2011-11-21

    The Compact Linear Collider requires a crab cavity on each beamline prior to the interaction point to rotate the bunches before collision. The cavities are X-band travelling wave type and are located close to the final doublet of the beam delivery system. This makes the beam very sensitive to transverse momentum imparted by wakefields; hence the wakefields must be tightly controlled. Of special concerns are the orthogonal polarisation of the operating mode and the fundamental monopole mode of the crab cavity. The former mode is at the same frequency as the operating mode of a cylindrically symmetric cavity and the latter one is at a lower frequency and hence is difficult to damp using a single means. In this paper major problematic modes of the crab cavity are investigated and damping requirements for them are calculated. Possibility of meeting the required wakefield control using waveguide damping and choke damping is thoroughly investigated. As a comparison, damped-detuning is also investigated.

  18. Ethnotaxonomical Study of Mole Crab (Crustacea:Hippoidea on Coastal Community of Cilacap

    Directory of Open Access Journals (Sweden)

    Dian Bhagawati

    2016-09-01

    Full Text Available Local wisdom is a cultural heritage that needs to be preserved. The Cilacap’s coastal communities have traditional taxonomy knowledge that hasn’t been informed, especially about mole crab. This study aimed to explore the ethnotaxonomy knowledge of sand crabs (Crustacea: Hippoidea in Widarapayung coastal communities. The purposive snowball sampling was used for the method, followed by observation and semi-structured interviews with 30 respondents. Data were analyzed descriptively based on observations and interviews. The results showed that the coastal communities in Widarapayung tourist areas could be divided into five groups, namely catchers, collectors, processors, traders, and consumers. The catcher was able to recognize and describe three types of sand crabs based on the shape of the body and their catchment areas. Captured crabs had the local name of ‘yutuk jambe’ (Emerita emeritus Linnaeus 1767, the appellation was based on carapace shape that resembled the shape of areca fruit; ‘Yutuk bathok’ (Hippa adactyla Fabricius 1787, had the carapace shape resembling a coconut shell, and ‘yutuk Kethek’ (Albunea symmysta Linnaeus 1758, had ornaments on the carapace surface similar with a monkey face, there were dense setae on the edge of the carapace, spiny long antennas and aggressively pinch when captured. The knowledge and skills of sand crabs classification and local name entitlement acquired by the people were in accordance with the Berlin’s model. How to CiteBhagawati, D., Anggoro, S., Zainuri, M. & Sya’rani, L. (2016. Ethnotaxonomical Study of Mole Crab (Crustacea:Hippoidea on Coastal Community of Cilacap. Biosaintifika: Journal of Biology & Biology Education, 8(2, 222-230.

  19. Effects of dietary lipids on the hepatopancreas transcriptome of Chinese mitten crab (Eriocheir sinensis.

    Directory of Open Access Journals (Sweden)

    Banghong Wei

    Full Text Available Fish oil supplies worldwide have declined sharply over the years. To reduce the use of fish oil in aquaculture, many studies have explored the effects of fish oil substitutions on aquatic animals. To illustrate the effects of dietary lipids on Chinese mitten crab and to improve the use of vegetable oils in the diet of the crabs, 60 male juvenile Chinese mitten crabs were fed one of five diets for 116 days: fish oil (FO, soybean oil (SO, linseed oil (LO, FO + SO (1:1, FSO, and FO + LO (1:1, FLO. Changes in the crab hepatopancreas transcriptome were analyzed using RNA sequencing. There were a total 55,167 unigenes obtained from the transcriptome, of which the expression of 3030 was significantly altered in the FLO vs. FO groups, but the expression of only 412 unigenes was altered in the FSO vs. FO groups. The diets significantly altered the expression of many enzymes involved in lipid metabolism, such as pancreatic lipase, long-chain acyl-CoA synthetases, carnitine palmitoyltransferase I, acetyl-CoA carboxylase, fatty acid synthase, and fatty acyl Δ9-desaturase. The dietary lipids also affected the Toll-like receptor and Janus activated kinase-signal transducers and activators of transcription signaling pathways. Our results indicate that substituting fish oil with vegetable oils in the diet of Chinese mitten crabs might decrease the digestion and absorption of dietary lipids, fatty acids biosynthesis, and immunologic viral defense, and increase β-oxidation by altering the expression of the relevant genes. Our results lay the foundation for further understanding of lipid nutrition in Chinese mitten crab.

  20. Effect of acanthocephalan parasites on hiding behaviour in two species of shore crabs.

    Science.gov (United States)

    Latham, A D M; Poulin, R

    2002-12-01

    The effect of acanthocephalan parasites (Profilicollis spp.) on the hiding behaviour during low tide of two species of shore crabs (intermediate hosts), Macrophthalmus hirtipes (Brachyura: Ocypodidae) and Hemigrapsus crenulatus (Brachyura: Grapsidae), was examined at Blueskin Bay, South Island, New Zealand. Exposed M. hirtipes were found to have significantly higher infection levels than did hidden conspecifics. This pattern was not observed for H. crenulatus. Mean cystacanth numbers were found to be considerably higher in M. hirtipes than H. crenulatus. Crabs exposed at low tide are at a greater risk of predation by definitive shorebird hosts than are hidden conspecifics. Preferential manipulation of one intermediate host species over another could influence diversity within ecosystems.