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Sample records for crabs maiopsis panamensis

  1. Susceptibility of spiny rats (Proechimys semispinosus to Leishmania (Viannia panamensis and Leishmania (Leishmania chagasi

    Directory of Open Access Journals (Sweden)

    BL Travi

    2002-09-01

    Full Text Available The role of Proechimys semispinosus as reservoir of Leishmania (Viannia panamensis on the Colombian Pacific coast was experimentally evaluated. The susceptibility to L. chagasi also was assessed to determine the utility of this rodent as a model for studying reservoir characteristics in the laboratory. Wild-caught animals were screened for natural trypanosomatid infections, and negative individuals were inoculated intradermally (ID in the snout or feet with 10(7 promastigotes of L. panamensis. L. chagasi was inoculated intracardially (10(7 promastigotes or ID in the ear (10(8 promastigotes. PCR-hybridization showed that 15% of 33 spiny rats were naturally infected with L. Viannia sp. Animals experimentally infected with L. panamensis developed non-ulcerated lesions that disappeared by the 7th week post-infection (p.i. and became more resistant upon reinfection. Infectivity to sand flies was low (1/20-1/48 infected/fed flies and transient, and both culture and PCR-hybridization showed that L. panamensis was cleared by the 13th week p.i. Animals inoculated with L. chagasi became subclinically infected and were non-infective to sand flies. Transient infectivity to vectors of spiny rats infected with L. panamensis, combined with population characteristics, e.g., abundance, exploitation of degraded habitats and high reproductive rates, could make them epidemiologically suitable reservoirs.

  2. Guzmania panamensis (Bromeliaceae – a new species from Talamanca Mountain in Veraguas province, Western Panama

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    Daniel Caceres Gonzalez

    2013-07-01

    Full Text Available Guzmania panamensis (Bromeliaceae, a new species so far endemic to Veraguas province, Western Panama, is described and illustrated. The new species is recognized due to its peduncle much longer than the leaves and its red floral bracts, shorter than the yellow flowers. The new species is compared to morphologically similar species, namely Guzmania monostachia, G. berteroniana, G. elvallensis, and G. skotakii.

  3. Guzmania panamensis (Bromeliaceae) - a new species from Talamanca Mountain in Veraguas province, Western Panama.

    Science.gov (United States)

    González, Daniel A Cáceres

    2013-01-01

    Guzmania panamensis (Bromeliaceae), a new species so far endemic to Veraguas province, Western Panama, is described and illustrated. The new species is recognized due to its peduncle much longer than the leaves and its red floral bracts, shorter than the yellow flowers. The new species is compared to morphologically similar species, namely Guzmania monostachia, Guzmania berteroniana, Guzmania elvallensis, and Guzmania skotakii.

  4. Guzmania panamensis (Bromeliaceae) – a new species from Talamanca Mountain in Veraguas province, Western Panama

    Science.gov (United States)

    González, Daniel A. Cáceres

    2013-01-01

    Abstract Guzmania panamensis (Bromeliaceae), a new species so far endemic to Veraguas province, Western Panama, is described and illustrated. The new species is recognized due to its peduncle much longer than the leaves and its red floral bracts, shorter than the yellow flowers. The new species is compared to morphologically similar species, namely Guzmania monostachia, Guzmania berteroniana, Guzmania elvallensis, and Guzmania skotakii. PMID:24198713

  5. 50 CFR Table 2 to Part 680 - Crab Species Code

    Science.gov (United States)

    2010-10-01

    ... crab Paralithodes platypus. 923 Golden (brown) king crab Lithodes aequispinus. 924 Scarlet king crab... crab Chionoecetes tanneri. 934 Triangle Tanner crab Chionoecetes angulatus. 940 Korean horsehair crab...

  6. 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...

  7. Post-dispersal predation and scatterhoarding of Dipteryx panamensis (Papilionaceae) seeds by rodents in Panama.

    Science.gov (United States)

    Forget, Pierre-Michel

    1993-05-01

    In tropical rain forests of Central America, the canopy tree Dipteryx panamensis (Papilionaceae) fruits when overall fruit biomass is low for mammals. Flying and arboreal consumers feed on D. panamensis and drop seeds under the parent or disperse them farther away. Seeds on the ground attract many vertebrate seed-eaters, some of them potential secondary seed dispersers. The fate of seeds artificially distributed to simulate bat dispersal was studied in relation to fruitfall periodicity and the visiting frequency of diurnal rodents at Barro Colorado Island (BCI), Panama. The frequency of visits by agoutis is very high at the beginning of fruitfall, but in the area close (50 m) away (Dipteryx-poor and Gustavia-rich area). Squirrels were usually observed in the Dipteryx-rich area. Along with intense post-dispersal seed predation by rodents in the Dipteryx-rich area, a significant proportion of seeds were cached by rodents in the Dipteryx-poor area. Post-dispersal seed predation rate was inversely related to hoarding rate. A significantly greater proportion of seeds was cached in March, especially more than 100 m from the nearest fruiting tree. This correlates with the mid-fruiting period, i.e. during the height of D. panamensis fruiting, when rodents seem to be temporarily satiated with the food supply at parent trees. Hoarding remained high toward April, i.e. late in the fruiting season of D. panamensis. Low survival of scatterhoarded seeds suggests that the alternative food supply over the animal's home-ranges in May-June 1990 was too low to promote survival of cached seeds. Seedlings are assumed to establish in the less-used area of the rodents' home-range when overall food supply is sufficient to satiate post-dispersal predators.

  8. Histopathological characteristics of cutaneous lesions caused by Leishmania Viannia panamensis in Panama

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    Kadir González

    2018-02-01

    Full Text Available ABSTRACT Cutaneous leishmaniasis (CL is an endemic disease in the Republic of Panama, caused by Leishmania (Viannia parasites, whose most common clinical manifestation is the presence of ulcerated lesions on the skin. These lesions usually present a chronic inflammatory reaction, sometimes granulomatous, with the presence of lymphocytes, plasma cells and macrophages. This study describes the histopathological characteristics found in the skin lesions of patients with CL caused by Leishmania (V. panamensis in Panama. We analyzed 49 skin biopsy samples from patients with clinical suspicion of CL, by molecular tests (PCR for subgenus Viannia and HSP-70 and by Hematoxylin-Eosin staining. Samples were characterized at the species level by PCR-HSP-70/RFLP. From the 49 samples studied, 46 (94% were positive by PCR and were characterized as Leishmania (V. panamensis. Of these, 48% were positive by Hematoxylin-Eosin staining with alterations being observed both, in the epidermis (85% and in the dermis (100% of skin biopsies. The inflammatory infiltrate was characterized according to histopathological patterns: lymphohistiocytic (50%, lymphoplasmacytic (61% and granulomatous (46% infiltration, being the combination of these patterns frequently found. The predominant histopathological characteristics observed in CL lesions caused by L. (V. panamensis in Panama were: an intense inflammatory reaction in the dermis with a combination of lymphohistiocytic, lymphoplasmacytic and granulomatous presentation patterns and the presence of ulcers, acanthosis, exocytosis and spongiosis in the epidermis.

  9. Aislamiento de genes diferencialmente expresados en amastigotes de Leishmania (Viannia panamensis

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    Róbinson Ramírez

    2001-04-01

    Full Text Available

    En Colombia cada año se diagnostican 6.500 casos nuevos de
    leishmaniasis cutánea y Leishmania (Viannia panamensis es la responsable del 95% de los casos. Durante su ciclo de vida, el parásito reside en el insecto vector como promastigote y se diferencia a amastigote después de ser inoculado en el hospedero mamífero. La transformación de promastigote a amastigote implica cambios morfológicos y bioquímicos que tienen lugar en el fagolisosoma del macrófago, y se caracterizan, entre otros, por la expresión de enzimas con actividad óptima a pH ácido además del cambio de los glicoconjugados de membrana. La supervivencia del parásito está asociada con su capacidad para inhibir funciones efectoras en el macrófago infectado permitiéndole al amastigote
    su replicación; sin embargo, poco se conoce acerca de los productos génicos expresados diferencialmente en este estadio por lo que nos propusimos con este trabajo aislar genes diferencialmente expresados en amastigotes de Leishmania (Viannia panamensis.

     

     

  10. Leishmania (Viannia) panamensis-induced cutaneous leishmaniasis in Balb/c mice: pathology.

    Science.gov (United States)

    Rojas, J. I.; Tani, E.; Orn, A.; Sánchez, C.; Goto, H.

    1993-01-01

    Leishmania (Viannia) panamensis infected Balb/c mice developed a progressive swelling in the injected footpad that grew to a tumour-like lesion from day 80 onwards. We did not observe any typical ulcera, necrosis or metastasis to other parts of the skin. Neither did we observe any histopathological changes in liver or spleen during the experiment. At the site of injection, we observed progressive changes ranging from a moderate, mixed inflammatory infiltrate with few leishmania amastigotes in the macrophages to an extensive inflammation composed of monomorphic vacuolated macrophages containing large numbers of parasites. A granulomatous pattern with presence of epithelioid cells and a few multinucleated giant cells was observed at the initial phase of the infection. During later stages, focal necrosis with polymorphonuclear neutrophils was seen. Lymph nodes presented granulomatous lesions in the subcapsular area, numerous plasma cells in the medullary cords and macrophages with leishmania organisms in dilated cortical sinuses at the 4th and the 6th months of infection. This Leishmania (Viannia) panamensis infected Balb/c mice seems to be a good model for continued studies of the pathogenesis of cutaneous leishmaniasis and also for drug trials in the development of new therapeutic tools. Images Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 PMID:8217783

  11. 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.)

  12. An epidemic outbreak of canine cutaneous leishmaniasis in Colombia caused by Leishmania braziliensis and Leishmania panamensis.

    Science.gov (United States)

    Vélez, Iván D; Carrillo, Lina M; López, Liliana; Rodríguez, Erwin; Robledo, Sara M

    2012-05-01

    The largest recorded outbreak of cutaneous leishmaniasis in Colombia's history occurred during 2005-2009 in soldiers of the Colombian Army, with ~40,000 cases. This outbreak was caused by the influx of military personnel into the jungle with the mission of combat illicit crops and the guerrilla. The soldiers remain for long periods within the rainforest and are exposed to the bite of infected sand flies. During the military activities, soldiers work with dogs specially trained to detect landmines, and therefore, dogs are also exposed to the infected sand flies and show high incidence of cutaneous leishmaniasis (CL). This work describes an epidemic outbreak of canine CL caused by Leishmania braziliensis and Leishmania panamensis in Colombia, South America. The clinical features of the disease and the response to treatment with pentavalent antimonials observed in 72 guard dogs from the Colombian Army are described. A program for prevention and control of canine CL is also discussed.

  13. Identification of a differentially expressed mRNA in axenic Leishmania panamensis amastigotes

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    José Arturo Gutiérrez

    2001-08-01

    Full Text Available Differential display technique was applied in order to identify transcripts which are present in axenic amastigotes but not in promastigotes of the Leishmania panamensis parasites. One of them was cloned and the sequence reveals an open reading frame of 364 amino acids (aprox. 40 kDa. The deduced protein is homologous to the serine/threonine protein kinases and specially to the mitogen activates protein kinases from eukaryotic species. Southern blot analysis suggest that this transcript, named lpmkh, is present in the genome of the parasite as a single copy gene. These results could imply that lpmkh could be involved in the differentiation process or the preservation of amastigotes in axenic conditions.

  14. Characteristics and properties of torrefied biomass pellets from Gmelina arborea and Dipterix panamensis at different times

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    Johanna Gaitán-Álvarez

    2016-01-01

    Full Text Available La torrefacción y peletización se han estudiado en la generación de calor a partir de residuos lignocelulósicos, para incrementar las propiedades energéticas del material. El objetivo del presente trabajo fue torrefaccionar aserrín de Gmelina arborea y Dipteryx panamensis a 200 °C en tres tiempos: 0, 15 y 20 minutos. Con las biomasas obtenidas se fabricaron pellets de 6 mm de diámetro y se evaluaron sus propiedades físicas, el poder calórico, la densidad y la propiedad mecánica de resistencia a la compresión. Ambas especies presentaron características físicas similares con respecto al diámetro (0.50 mm, longitud (21.50 mm y porcentaje de absorción de agua (6.00 %. El poder calórico aumentó de 9,749 kJ·kg-1 en la biomasa sin torrefaccionar a 18,126 kJ·kg-1 en la biomasa torrefaccionada. Los pellets de D. panamesis presentaron mayor densidad y resistencia a la compresión que los de G. arborea. Con base en los resultados, la resistencia a la compresión del pellet disminuye cuando el tiempo de torrefacción aumenta. Existe correlación positiva entre la densidad de los pellets y la resistencia a la compresión. La especie D. panamensis presenta mejor comportamiento a la torrefacción y peletización que la madera de G. arborea.

  15. BODY WEIGHT AS A DETERMINANT OF CLINICAL EVOLUTION IN HAMSTERS (Mesocricetus auratus INFECTED WITH Leishmania (Viannia panamensis

    Directory of Open Access Journals (Sweden)

    Angela Maria Gomez-Galindo

    2013-09-01

    Full Text Available SUMMARY The clinical outcome of infection with Leishmania species of the subgenus Viannia in hamster model (Mesocricetus auratus has shown to be different depending on experimental protocol. Body weight has been a relevant determinant of the clinical outcome of the infection in hamsters with visceral leishmaniasis but its importance as a clinical parameter in hamsters with cutaneous leishmaniasis is not known. In this study, the clinical evolution of infection with L. (V panamensis was evaluated in juvenile and adult male hamsters during 11 weeks by comparing clinical parameters such as attitude, temperature, respiratory rate, appearance of the stool, and body weight between infected and non-infected groups. Results showed that body weight decreased in adult hamsters after infection by L. (V panamensis; this observation supports the use of body weight as an additional parameter to define the management or treatment of cutaneous leishmaniasis in infected adult hamsters used as an animal experimental model for leishmaniasis.

  16. Feeding assemblages of mammals at fruiting Dipteryx panamensis (Papilionaceae) trees in Panama: seed predation, dispersal, and parasitism

    OpenAIRE

    Bonaccorso, Frank J.; Glanz, William E.; Sandford, Clark M.

    2016-01-01

    Fruiting almendro trees, Dipteryx panamensis, are visited by sixteen species of mammals that eat the fruits exocarp or seed. Seeds are susceptible to predation by granivorous rodents and peccaries. Most mammals that visit Dipteryx trees act as commensals·, eating only the fleshy exocarp and dropping the endocarp with its enclosed seed below the parent tree. So me primates, tayras, coatis, and kinkajous occasionally disperse Dipteryx seeds, but only Artibeus lituratus, Dasyprocta punctata, and...

  17. Evaluation of a Multilocus Sequence Typing (MLST) scheme for Leishmania (Viannia) braziliensis and Leishmania (Viannia) panamensis in Colombia.

    Science.gov (United States)

    Herrera, Giovanny; Hernández, Carolina; Ayala, Martha S; Flórez, Carolina; Teherán, Aníbal A; Ramírez, Juan David

    2017-05-12

    Leishmaniases are parasitic vector-borne diseases affecting more than 12 million people in 98 countries. In Colombia, leishmaniasis is widespread and the most common clinical manifestation is cutaneous, mainly caused by L. panamensis and L. braziliensis. Currently, the genetic diversity of these species in Colombia is unknown. To address this, we applied molecular techniques for their characterization, using multilocus sequence typing (MLST) to explore the genetic variability and phylodynamics of the disease. Seven previously described genetic markers were selected highlighting the implementation of a mitochondrial marker. Markers were applied to 163 samples from isolates obtained between 1980 and 2001. The identification of the samples showed an excellent correlation with typing tests previously applied (MLEE, monoclonal antibodies). Isolates of L. braziliensis showed greater genetic diversity than L. panamensis, and a greater number of diploid sequence types (DSTs). In addition, the geographical distribution of DSTs for each species were obtained through georeferencing maps. To our knowldge, this study represents the first description of the genetic variability of L. panamensis in Colombia and South America, and is the first to propose a scheme of MLST for epidemiological surveillance of leishmaniasis in the country.

  18. Capacidad antioxidante y contenido de fenoles totales de Hyptis spp., P. Heptaphyllum, T. Panamensis, T. Rhoifolia, y Ocotea sp.

    Directory of Open Access Journals (Sweden)

    Geovanna Tafurt García

    2015-05-01

    Full Text Available En este trabajo se evaluó la posible correlación entre las actividades antioxidantes, el contenido de fenoles totales (CFT y la composición química de Lamiaceae (H. conferta, H. dilatata, H. mutabilis, H. suaveolens, Burseraceae (P. heptaphyllum, T. rhoifoila, T. panamensis y Lauraceae (Ocotea sp.. Para los extractos etanólicos obtenidos por maceración en frio y evaporación a sequedad, la Capacidad Antioxidante Equivalente al Trolox o la Actividad Antioxidante Total (AAT, fueron determinadas mediante un ensayo colorimétrico con el catión radical ABTS, la Concentración Efectiva (EC50 fue evaluada con el radical DPPH, y el Contenido de Fenoles Totales (CFT, fue establecido mediante el método de Folin-Ciocalteu. Tanto la AAT como la EC50 estuvieron altamente correlacionados con el CFT. Las cortezas de T. rhoifolia y T. panamensis mostraron las capacidades antioxidantes más altas. Las Burseraceae spp. mostraron los TPC más altos y las Lamiaceae (Hyptis spp. mostraron los TPC más bajos.

  19. Pollen dispersal and genetic structure of the tropical tree Dipteryx panamensis in a fragmented Costa Rican landscape.

    Science.gov (United States)

    Hanson, Thor R; Brunsfeld, Steven J; Finegan, Bryan; Waits, Lisette P

    2008-04-01

    In the face of widespread deforestation, the conservation of rainforest trees relies increasingly on their ability to maintain reproductive processes in fragmented landscapes. Here, we analysed nine microsatellite loci for 218 adults and 325 progeny of the tree Dipteryx panamensis in Costa Rica. Pollen dispersal distances, genetic diversity, genetic structure and spatial autocorrelation were determined for populations in four habitats: continuous forest, forest fragments, pastures adjacent to fragments and isolated pastures. We predicted longer but less frequent pollen movements among increasingly isolated trees. This pattern would lead to lower outcrossing rates for pasture trees, as well as lower genetic diversity and increased structure and spatial autocorrelation among their progeny. Results generally followed these expectations, with the shortest pollen dispersal among continuous forest trees (240 m), moderate distances for fragment (343 m) and adjacent pasture (317 m) populations, and distances of up to 2.3 km in isolated pastures (mean: 557 m). Variance around pollen dispersal estimates also increased with fragmentation, suggesting altered pollination conditions. Outcrossing rates were lower for pasture trees and we found greater spatial autocorrelation and genetic structure among their progeny, as well as a trend towards lower heterozygosity. Paternal reproductive dominance, the pollen contributions from individual fathers, did not vary among habitats, but we did document asymmetric pollen flow between pasture and adjacent fragment populations. We conclude that long-distance pollen dispersal helps maintain gene flow for D. panamensis in this fragmented landscape, but pasture and isolated pasture populations are still at risk of long-term genetic erosion.

  20. 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...

  1. Ocurrence of the sea anemone Telmatactis panamensis (Verrill, 1869 (Cnidaria: Anthozoa: Actiniaria at Isla del Coco National Park, Costa Rica

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    Fabián H. Acuña

    2012-11-01

    Full Text Available The sea anemone fauna of Isla del Coco National Park (also known as Cocos Island Nacional Park, Pacific Costa Rica is poorly known. In the present work we report the first occurrence of the species Telmatactis panamensis. Individuals of this sea anemone (n=24 were collected at Chatham Bay intertidal and at 15m depth in Punta Ulloa, in both cases attached to rocks; during the expedition UCR-UNA-COCO-I in April 2010. We provide photographs of live individuals, external anatomy and an inventory of cnidae of the studied specimens. Possibly this species is extended to greater depth as observed by other authors in the Galápagos Islands.

  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. Ocurrence of the sea anemone Telmatactis panamensis (Verrill, 1869 (Cnidaria: Anthozoa: Actiniaria at Isla del Coco National Park, Costa Rica

    Directory of Open Access Journals (Sweden)

    Fabián H. Acuña

    2012-11-01

    Full Text Available The sea anemone fauna of Isla del Coco National Park (also known as Cocos Island Nacional Park, Pacific Costa Rica is poorly known. In the present work we report the first occurrence of the species Telmatactis panamensis. Individuals of this sea anemone (n=24 were collected at Chatham Bay intertidal and at 15m depth in Punta Ulloa, in both cases attached to rocks; during the expedition UCR-UNA-COCO-I in April 2010. We provide photographs of live individuals, external anatomy and an inventory of cnidae of the studied specimens. Possibly this species is extended to greater depth as observed by other authors in the Galápagos Islands.La fauna de anémonas de mar es prácticamente desconocida para el Parque Nacional Isla del Coco (Costa Rica. En el presente trabajo se reporta por primera vez la presencia de la especie Telmatactis panamensis. Individuos de esta anémona de mar fueron colectados en el intermareal de Bahía Chatham y a 15m de profundidad en Punta Ulloa, en ambos casos adheridas a rocas; durante la expedición UCR-UNA-COCO-I en Abril de 2010. Se proveen fotografías de ejemplares vivos, datos de su anatomía externa y un inventario del cnidae de los especímenes estudiados. Posiblemente esta especie se extienda a mayor profundidad, tal como fue observado por otros autores para ejemplares de las Islas Galápagos.

  4. 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...

  5. Characterization of a Freshwater Crab Sudanonautes aubryi ...

    African Journals Online (AJOL)

    SARAH

    2014-01-31

    Jan 31, 2014 ... Recently, Cumberlidge and. Reed (2004) described the freshwater crab genus. Erimetopus of Congo basin. Sudanonautes aubryi, like all others edible crabs are also poorly understood. This preliminary study was undertaken to collect and realize a biometric characterization of this common freshwater crab ...

  6. 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...

  7. [Morphology and cytochemistry of Aedes aegypti's cell cultures (Diptera: Culicidae) and susceptibility to Leishmania panamensis (Kinetoplastida: Trypanosomatidae)].

    Science.gov (United States)

    Miranda, Alfonso Arturo; Sarmiento, Ladys; Caldas, María Leonor; Zapata, Cristina; Bello, Felio Jesús

    2008-06-01

    Morphology and cytochemistry of Aedes aegypti's cell cultures (Diptera: Culicidae) and susceptibility to Leishmania panamensis (Kinetoplastida: Trypanosomatidae). The first cellular line of Aedes aegypti was developed by Grace in 1966; afterwards, other cellular lines of this species have been generated. These have been used for the study of pathogenic organisms like viruses, bacteria and parasites, which demonstrates their importance in biomedical applications. This research describes, for the first time, some cytochemical characteristics of A. aegypti cell cultures, that were infected with (MHOM/CO/87CL412) strain of Leishmania panamensis. A morphological study of the cell culture was also carried out. Maintenance of the cell culture, parasites and infection in vitro were carried out in the Laboratory of Entomology, Cell Biology and Genetics of the Universidad de La Salle. The cell cultures infected with the parasite were maintained in a mixture of mediums Grace/L15, supplemented with 10 % fetal bovine serum (FBS) at pH 6.8 and a temperature of 26 degrees C, during 3, 6 and 9 post-infection days. After this, these cell cultures were processed through High Resolution Light Microscopy (HRLM) and Transmission Electron Microscopy (TEM) based on standard protocols defined by the Group of Microscopy and Image Analyses of the Instituto Nacional de Salud. Semi-fine slices of 1 microm colored with toluidine blue were used for the morphological analysis of the culture, and ultra fine cuts of 60 to 90 nm stained with uranyl acetate and lead citrate where used for the ultrastructural study. In addition, PAS and peroxidase staining was carried out in cells fixed with methanol. The morphometric study was analyzed with software ImageJ (NIH). In the semi-fine slices, small cells were observed showing fibroblastic appearance 10.84 +/- 2.54 microm in length and 5.31 +/- 1.26 microm wide; other cells had epithelial appearance with a great peripheral nucleus, voluminous and

  8. Historical insights on growth rates of the reef-building corals Pavona gigantea and Porites panamensis from the Northeastern tropical Pacific.

    Science.gov (United States)

    Tortolero-Langarica, J J A; Carricart-Ganivet, J P; Cupul-Magaña, A L; Rodríguez-Troncoso, A P

    2017-12-01

    Historical coral growth assessed by sclerochronology records provides an environmental retrospective and future perspective on the maintenance of coral-reef ecosystems. Three growth parameters, extension rate, skeletal density, and calcification rate were evaluated over the past two decade's interval (1988-2013) in different gender of two massive corals Pavona gigantea and Porites panamensis. The species P. gigantea calcified two-times faster (0.84 ± 0.29 g cm -2 yr -1 ) than P. panamensis (0.36 ± 0.15 g cm -2 yr -1 ); and male colonies presents13-58% higher calcification rates than females. Annual growth parameters do not show significant trends over the period 1988-2013, but significant, growth disruption associated with ENSO events. The data presented here suggest that P.gigantea and P.panamensis from the area have developed phenotypic plasticity to a wide range of environmental condition; the life history of both species is reflected in their calcification rates during both optimal and non-optimal conditions over the last two decades. Massive species develop denser structures that provide a permanent habitat to many marine species and contributes to the long-term maintenance of coral reef communities in the eastern tropical Pacific. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. 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.

  10. 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...

  11. The Crab Nebula flaring activity

    Directory of Open Access Journals (Sweden)

    G. Montani

    2014-12-01

    Full Text Available 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 ∼1015 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 ∼109, 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.

  12. 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.

  13. Novel Geometries for the LHC CRAB Cavity

    CERN Document Server

    Hall, Ben

    2010-01-01

    In 2017 the LHC is envisioned to increase its luminosity via an upgrade. This upgrade is likely to require a large crossing angle hence a crab cavity is required to align the bunches prior to collision. There are two possible schemes for crab cavity implementation, global and local. In a global crab cavity the crab cavity is far from the IP and the bunch rotates back and forward as it traverses around the accelerator in a closed orbit. For this scheme a two-cell elliptical squashed cavity at 800 MHz is preferred. To avoid any potential beam instabilities all the parasitic modes of the cavities must be damped strongly, however crab cavities have lower order and same order modes in addition to the usual higher order modes and hence a novel damping scheme must be used to provide sufficient damping of these modes. In the local scheme two crab cavities are placed at each side of the IP two start and stop rotation of the bunches. This would require crab cavities much smaller transversely than in the global scheme b...

  14. 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.

  15. Final focus designs for crab waist colliders

    CERN Document Server

    AUTHOR|(CDS)2084369; Levichev, Evgeny; Piminov, Pavel

    2016-01-01

    The crab waist collision scheme promises significant luminosity gain. The successful upgrade of the DA$\\Phi$NE 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 DA$\\Phi$NE and SuperKEKB, presently undergoing commissioning, for the projects of SuperB in Italy, CTau in Novosibirsk and FCC-ee at CERN.

  16. 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.

  17. Design of the ILC Crab Cavity System

    Energy Technology Data Exchange (ETDEWEB)

    Adolphsen, C.; Beard, C.; Bellantoni, L.; Burt, G.; Carter, R.; Chase, B.; Church, M.; Dexter, A.; Dykes, M.; Edwards, H.; Goudket, P; Jenkins, R.; Jones, R.M.; Kalinin,; Khabiboulline, T.; Ko, K.; Latina, A.; Li, Z.; Ma, L.; McIntosh, P.; Ng, C.; /SLAC /Daresbury /Fermilab /Cockcroft Inst. Accel. Sci. Tech. /CERN

    2007-08-15

    The International Linear Collider (ILC) has a 14 mrad crossing angle in order to aid extraction of spent bunches. As a result of the bunch shape at the interaction point, this crossing angle at the collision causes a large luminosity loss which can be recovered by rotating the bunches prior to collision using a crab cavity. The ILC baseline crab cavity is a 9-cell superconducting dipole cavity operating at a frequency of 3.9 GHz. In this paper the design of the ILC crab cavity and its phase control system, as selected for the RDR in February 2007 is described in fuller detail.

  18. 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.

  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. 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

  1. 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...

  2. 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

  3. Hermit to king, or hermit to all: multiple transitions to crab-like forms from hermit crab ancestors.

    Science.gov (United States)

    Tsang, Ling Ming; Chan, Tin-Yam; Ahyong, Shane T; Chu, Ka Hou

    2011-10-01

    The Anomura presents the greatest degree of morphological disparity in the decapod Crustacea, with body forms ranging from the symmetrical and asymmetrical hermit crabs to squat lobsters and king crabs. The phylogeny of the anomurans has been fraught with controversy. Recent debate has focused primarily on the phenomenon of carcinization, the evolution of crab-like form from a non-crab-like ancestor, focused chiefly on derivation of king crabs from asymmetrical hermit crabs--the "hermit to king" hypothesis. We show by phylogenetic analysis of five nuclear protein-coding gene sequences that hermit crabs have a single origin, but surprisingly, that almost all other major clades and body forms within the Anomura, are derived from within the hermit crabs. The crab-like form and squat lobster form have each evolved at least twice from separate symmetrical hermit crab ancestors. In each case, a carcinization trend can be posited via a transition series from the initial symmetrical long-tailed hermit crab form, through the intermediate squat lobster or asymmetrical hermit crab form, to the final crab-like form. Adaptation to dextral shell habitation evolved at least twice, once in an exclusively deep-water clade and once in the common ancestor of all other asymmetrical hermit crabs (from which king crabs are derived). These remarkable cases of parallelism suggest considerable phenotypic flexibility within the hermit crab ground plan, with a general tendency toward carcinization. Rather than having a separate origin from other major clades, hermit crabs have given rise to most other major anomuran body types.

  4. 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...

  5. 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 ...

  6. Shell utilization and morphometries of the hermit crab Diogenes ...

    African Journals Online (AJOL)

    Fecundity, shell utilization, and crab and associated shell morphometries were investigated for the hermit crab Diogenes brevirostris collected from three intertidal sites in the eastern Cape. The relationship between crab fresh mass and egg number was linear. D. brevirostris was found to occupy 33 gastropod shell species ...

  7. Ghost crabs on a treadmill: Oxygen uptake and haemocyanin ...

    African Journals Online (AJOL)

    1990-04-17

    Apr 17, 1990 ... 1991,26(2). Ghost crabs on a treadmill: Oxygen uptake and haemocyanin oxygen affinity. W.J, Van Aardt ... Ghost crabs Ocypode ceratophthalmus were exercised on a specially constructed treadmill. At a running speed of 13 ...... associated exchange of respiratory gasses in the land hermit crab (Coenobila.

  8. 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 ...

  9. El análisis molecular y el inmunogénico sugieren la ausencia de las proteínas hidrofílicas de superficie en Leishmania (Viannia panamensis

    Directory of Open Access Journals (Sweden)

    Marcel Marín

    2008-09-01

    Full Text Available Introducción. Los dos subgéneros en los cuales se divide el género Leishmania: Viannia y Leishmania, presentan diferencias significativas en las manifestaciones clínicas que causan, en su comportamiento de crecimiento en cultivos in vitro, en sus características genéticas y en la expresión de varias proteínas, entre ellas las de la familia hidrofílica de superficie superficie. Objetivo. Caracterizar las proteínas hidrofílicas de superficie en Leishmania (Viannia panamensis. Materiales y métodos. Se amplificaron los genes hasp en L. (V. panamensis usando cebadores específicos para la especie Leishmania (Leishmania major. Los productos de la amplificación fueron clonados, secuenciados y analizados con herramientas bioinformáticas. Posteriormente, se realizó un análisis serológico por medio de ensayo inmunoabsorbente ligado a enzimas y Western blot para detectar la presencia de anticuerpos específicos contra las proteínas hidrofílicas recombinantes de superficie de L. (L. major en sueros de pacientes con leishmaniasis de zonas endémicas de Colombia. Resultados. Se encontró una copia de un pseudogen en L. (V. panamensis, el cual presentó una identidad del 60% con el gen haspa de L. (L. major. Sólo se encontraron anticuerpos contra las proteínas recombinantes de superficie hidrofílicas en sueros de pacientes con leishmaniasis visceral. Conclusión. Estos resultados sugieren que no existe ninguna copia de un gen funcional hasp en L. (V. panamensis, lo que indica una pérdida de la familia de genes en esta especie de Leishmania perteneciente al subgénero Viannia.

  10. Sex-associated variations in coral skeletal oxygen and carbon isotopic composition of Porites panamensis in the southern Gulf of California

    Science.gov (United States)

    Cabral-Tena, Rafael A.; Sánchez, Alberto; Reyes-Bonilla, Héctor; Ruvalcaba-Díaz, Angel H.; Balart, Eduardo F.

    2016-05-01

    Coral δ18O variations are used as a proxy for changes in sea surface temperature (SST) and seawater isotope composition. Skeletal δ13C of coral is frequently used as a proxy for solar radiation because most of its variability is controlled by an interrelationship between three processes: photosynthesis, respiration, and feeding. Coral growth rate is known to influence the δ18O and δ13C isotope record to a lesser extent than environmental variables. Recent published data show differences in growth parameters between female and male coral in the gonochoric brooding coral Porites panamensis; thus, skeletal δ18O and δ13C are hypothesized to be different in each sex. To test this, this study describes changes in the skeletal δ18O and δ13C record of four female and six male Porites panamensis coral collected in Bahía de La Paz, Mexico, whose growth bands spanned 12 years. The isotopic data were compared to SST, precipitation, photosynthetically active radiation (PAR), chlorophyll a, and skeletal growth parameters. Porites panamensis is a known gonochoric brooder whose growth parameters are different in females and males. Splitting the data by sexes explained 81 and 93 % of the differences of δ18O, and of δ13C, respectively, in the isotope record between colonies. Both isotope records were different between sexes. δ18O was higher in female colonies than in male colonies, with a 0.31 ‰ difference; δ13C was lower in female colonies, with a 0.28 ‰ difference. A difference in the skeletal δ18O could introduce an error in SST estimates of ≈ 1.0 to ≈ 2.6 °C. The δ18O records showed a seasonal pattern that corresponded to SST, with low correlation coefficients (-0.45, -0.32), and gentle slopes (0.09, 0.10 ‰ °C-1) of the δ18O-SST relation. Seasonal variation in coral δ18O represents only 52.37 and 35.66 % of the SST cycle; 29.72 and 38.53 % can be attributed to δ18O variability in seawater. δ13C data did not correlate with any of the environmental

  11. Black yeast-like fungi associated with Lethargic Crab Disease (LCD) in the mangrove-land crab, Ucides cordatus (Ocypodidae)

    NARCIS (Netherlands)

    Vicente, V.A.; Orelis-Ribeiro, R.; Najafzadeh, M.J.; Sun, J.; Schier Guerra, R.; Miesch, S.; Ostrensky, A.; Meis, J.F.; Klaassen, C.H.; de Hoog, G.S.; Boeger, W.A.

    2012-01-01

    Lethargic Crab Disease (LCD) caused extensive epizootic mortality of the mangrove land crab Ucides cordatus (Brachyura: Ocypodidae) along the Brazilian coast, mainly in the Northeastern region. The disease was named after the symptoms of slow movement of infected crabs. Causative agents were

  12. 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.

  13. Novel Geometries for the LHC Crab Cavity

    Energy Technology Data Exchange (ETDEWEB)

    B. Hall, G. Burt, C. Lingwood, R. Rimmer, H. Wang

    2010-05-23

    The planned luminosity upgrade to LHC is likely to necessitate a large crossing angle and a local crab crossing scheme. For this scheme crab cavities align bunches prior to collision. The scheme requires at least four such cavities, a pair on each beam line either side of the interaction point (IP). Upstream cavities initiate rotation and downstream cavities cancel rotation. Cancellation is usually done at a location where the optics has re-aligned the bunch. The beam line separation near the IP necessitates a more compact design than is possible with elliptical cavities such as those used at KEK. The reduction in size must be achieved without an increase in the operational frequency to maintain compatibility with the long bunch length of the LHC. This paper proposes a suitable superconducting variant of a four rod coaxial deflecting cavity (to be phased as a crab cavity), and presents analytical models and simulations of suitable designs.

  14. Novel Geometries for the LHC Crab Cavity

    Energy Technology Data Exchange (ETDEWEB)

    B. Hall,G. Burt,C. Lingwood,Robert Rimmer,Haipeng Wang; Hall, B. [CI Lancaster University (Great Britain); Burt, G. [CI Lancaster University (Great Britain); Lingwood, C. [CI Lancaster University (Great Britain); Rimmer, Robert [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Wang, Haipeng [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)

    2010-05-01

    The planned luminosity upgrade to LHC is likely to necessitate a large crossing angle and a local crab crossing scheme. For this scheme crab cavities align bunches prior to collision. The scheme requires at least four such cavities, a pair on each beam line either side of the interaction point (IP). Upstream cavities initiate rotation and downstream cavities cancel rotation. Cancellation is usually done at a location where the optics has re-aligned the bunch. The beam line separation near the IP necessitates a more compact design than is possible with elliptical cavities such as those used at KEK. The reduction in size must be achieved without an increase in the operational frequency to maintain compatibility with the long bunch length of the LHC. This paper proposes a suitable superconducting variant of a four rod coaxial deflecting cavity (to be phased as a crab cavity), and presents analytical models and simulations of suitable designs.

  15. Efficient monitoring of CRAB jobs at CMS

    Science.gov (United States)

    Silva, J. M. D.; Balcas, J.; Belforte, S.; Ciangottini, D.; Mascheroni, M.; Rupeika, E. A.; Ivanov, T. T.; Hernandez, J. M.; Vaandering, E.

    2017-10-01

    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.

  16. Screening of the topical anti-inflammatory activity of the bark of Acacia cornigera Willdenow, Byrsonima crassifolia Kunth, Sweetia panamensis Yakovlev and the leaves of Sphagneticola trilobata Hitchcock.

    Science.gov (United States)

    Maldini, M; Sosa, S; Montoro, P; Giangaspero, A; Balick, M J; Pizza, C; Della Loggia, R

    2009-04-21

    An investigation of topical anti-inflammatory activity was undertaken on plants used in Central America traditional medicine. Four herbal drugs used in the folk medicine of Central America to treat inflammatory skin affections (Acacia cornigera bark, Byrsonima crassifolia bark, Sphagneticola trilobata leaves and Sweetia panamensis bark) were evaluated for their topical anti-inflammatory activity. Petroleum ether, chloroform and methanol extracts were obtained for herbal medicines and then extracts were tested on Croton oil-induced ear dermatitis model in mice. Almost all the extracts reduced the Croton oil-induced ear dermatitis in mice and the chloroform ones showed the highest activity, with ID(50) (dose giving 50% oedema inhibition) values ranging from 112 microg/cm(2) (Byrsonima crassifolia) to 183 microg/cm(2) (Sphagneticola trilobata). As reference, ID(50) of the non-steroidal anti-inflammatory drug indomethacin was 93 microg/cm(2). Lipophilic extracts from these species can be regarded as potential sources of anti-inflammatory principles.

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

    African Journals Online (AJOL)

    1997-02-06

    Feb 6, 1997 ... CHASE, l.D. 1974. Models of hierarchy formation in animal societies. Behav. Sct. 19: 374-382. DU PREEZ, H.H., STEENKAMP, V.E. & SCHOONBEE, HJ. 1993. Bioaccumulation of zinc and lead in selected tissues and organs of the freshwater crab. PotamonQutes warreni. Sci. Tot. Environ. Suppl.: 469-478.

  18. 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.

  19. Swimming of the pea crab (Pinnotheres pisum)

    NARCIS (Netherlands)

    Versteegh, C.P.C.; Muller, M.

    2014-01-01

    Aquatic organisms have to deal with different hydrodynamic regimes, depending on their size and speed during locomotion. The pea crab swims by beating the third and fourth pereiopod on opposite sides as pairs. Using particle tracking velocimetry and high-speed video recording, we quantify the

  20. 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

  1. 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.

  2. 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.

  3. Blood Collection from the American Horseshoe Crab, Limulus Polyphemus

    OpenAIRE

    Armstrong, Peter; Conrad, Mara

    2008-01-01

    The horseshoe crab has the best-characterized immune system of any long-lived invertebrate. The study of immunity in horseshoe crabs has been facilitated by the ease in collecting large volumes of blood and from the simplicity of the blood. Horseshoe crabs show only a single cell type in the general circulation, the granular amebocyte. The plasma has the salt content of sea water and only three abundant proteins, hemocyanin, the respiratory protein, the C-reactive proteins, which function in ...

  4. Eficacia y tolerancia de la pentamidina en el tratamiento de la leishmaniasis cutánea producida por Leishmania (V. panamensis en Colombia

    Directory of Open Access Journals (Sweden)

    Sara María Robledo

    2006-10-01

    Full Text Available Introducción. El tratamiento de elección de la leishmaniasis cutánea es el antimonio pentavalente con una eficacia cercana al 85%; sin embargo, debido a los serios efectos adversos y a la aparición cada vez más frecuente de resistencia al tratamiento, se hace necesaria la búsqueda de alternativas terapéuticas. Objetivo. Evaluar la eficacia terapéutica y la tolerancia del isotianato de pentamidina con un ensayo clínico piloto con pacientes con leishmaniasis cutánea producida por L. (V panamensis en Colombia. Materiales y métodos. Se incluyeron en el estudio 63 pacientes los cuales fueron tratados por vía intramuscular con 4 mg de isotianato de pentamidina/kg de peso/ interdiario por cuatro dosis, con seguimiento clínico por seis meses. Resultados. De los 63 paciente incluidos, 43 fueron evaluados durante los seis meses del estudio y de estos 37 (86% presentaron curación de todas sus lesiones mes y medio después de terminar el tratamiento. Cinco pacientes (11,6% fallaron al tratamiento por no cicatrización de las lesiones y uno presentó recaída. En general el tratamiento fue bien tolerado; los efectos adversos principales fueron dolor y edema en el sitio de aplicación, mareo y fiebre, de intensidad leve a moderada. No se presentaron hipoglucemia, hipotensión ni diabetes. Discusión. Los resultados del presente estudio validan los hallazgos de eficacia de la pentamidina para el tratamiento de la leishmaniasis cutánea en Colombia y en Brasil. Se destaca una baja frecuencia e intensidad de los efectos colaterales en la población civil donde no se encontró ningún paciente con efectos secundarios serios.

  5. Invasive Crabs in the Barents Sea

    DEFF Research Database (Denmark)

    Kaiser, Brooks; Fernandez, Linda; Kourantidou, Melina

    compare differences in the ecology and economics of the two species to enhance understanding of the trade-offs inherent in managing these economically profitable yet risky invaders. We then expand the application by using these ongoing invasions to illustrate the anticipated disruptions (with potentially......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...... both positive and negative impacts) from other introductions or range expansions of commercial species and the management steps that should be taken at earlier stages, including monitoring and preventive measures, in the changing ecological processes to minimize negative impacts....

  6. Status of the ILC Crab Cavity Development

    Energy Technology Data Exchange (ETDEWEB)

    Burt, G.; Dexter, A.; /Cockcroft Inst. Accel. Sci. Tech.; Beard, C.; Goudket, P.; McIntosh, P.; /Daresbury; Bellantoni, L.; /Fermilab; Grimm, T.; Li, Z.; Xiao, L.; /SLAC

    2011-10-20

    The International Linear Collider (ILC) will require two dipole cavities to 'crab' the electron and positron bunches prior to their collision. It is proposed to use two 9 cell SCRF dipole cavities operating at a frequency of 3.9 GHz, with a transverse gradient of 3.8MV/m in order to provide the required transverse kick. Extensive numerical modelling of this cavity and its couplers has been performed. Aluminium prototypes have been manufactured and tested to measure the RF properties of the cavity and couplers. In addition single cell niobium prototypes have been manufactured and tested in a vertical cryostat. The International Collider (ILC) [1] collides bunches of electrons and positrons at a crossing angle of 14 mrad. The angle between these bunches causes a loss in luminosity due to geometric effects [2]. The luminosity lost from this geometric effect can be recovered by rotating the bunches into alignment prior to collision. One possible method of rotating the bunches is to use a crab cavity [3]. A crab cavity is a transverse defecting cavity, where the phase of the cavity is such that the head and tail of the bunch receive equal and opposite kicks. As the bunches are only 500 nm wide in the horizontal plane, the cavity phase must be strictly controlled to avoid the bunch centre being deflected too much. In order to keep the phase stability within the required limits it is required that the cavity be superconducting to avoid thermal effects in both the cavity and its RF source. At the location of the crab cavity in the ILC there is only 23 cm separation between the centre of the cavity and the extraction line, hence the cavity must be small enough to fit in this space. This, along with the difficulty of making high frequency SRF components, set the frequency of the cavity to 3.9 GHz.

  7. 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)

  8. Prevalence, characterization and sources of Listeria monocytogenes in blue crab (Callinectus sapidus) meat and blue crab processing plants.

    Science.gov (United States)

    Pagadala, Sivaranjani; Parveen, Salina; Rippen, Thomas; Luchansky, John B; Call, Jeffrey E; Tamplin, Mark L; Porto-Fett, Anna C S

    2012-09-01

    Seven blue crab processing plants were sampled to determine the prevalence and sources of Listeria spp. and Listeria monocytogenes for two years (2006-2007). A total of 488 raw crabs, 624 cooked crab meat (crab meat) and 624 environmental samples were tested by standard methods. Presumptive Listeria spp. were isolated from 19.5% of raw crabs, 10.8% of crab meat, and 69.5% of environmental samples. L. monocytogenes was isolated from 4.5% of raw crabs, 0.2% of crab meat, and 2.1% of environmental samples. Ninety-seven percent of the isolates were resistant to at least one of the ten antibiotics tested. Eight different serotypes were found among 76 L. monocytogenes isolates tested with the most common being 4b, 1/2b and 1/2a. Automated EcoRI ribotyping differentiated 11 ribotypes among the 106 L. monocytogenes isolates. Based on ribotyping analysis, the distribution of the ribotypes in each processing plant had a unique contamination pattern. A total of 92 ApaI and 88 AscI pulsotypes among the 106 L. monocytogenes isolates were found and distinct pulsotypes were observed in raw crab, crab meat and environmental samples. Ribotypes and serotypes recovered from crab processing plants included subtypes that have been associated with listeriosis cases in other food outbreaks. Our findings suggest that molecular methods may provide critical information about sources of L. monocytogenes in crab processing plants and will augment efforts to improve food safety control strategies such as targeting specific sources of contamination and use of aggressive detergents prior to sanitizing. Copyright © 2012 Elsevier Ltd. All rights reserved.

  9. 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.

  10. 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

  11. 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.

  12. Comparative analysis of the proximate and elemental composition of the blue crab Callinectes sapidus, the warty crab Eriphia verrucosa, and the edible crab Cancer pagurus

    Directory of Open Access Journals (Sweden)

    Maurizio Zotti

    2016-02-01

    Full Text Available The proximate composition and element contents of claw muscle tissue of Atlantic blue crabs (Callinectes sapidus were compared with the native warty crab (Eriphia verrucosa and the commercially edible crab (Cancer pagurus. The scope of the analysis was to profile the chemical characteristics and nutritive value of the three crab species. Elemental fingerprints showed significant inter-specific differences, whereas non-significant variations in the moisture and ash contents were observed. In the blue crab, protein content was significantly lower than in the other two species, while its carbon content resulted lower than that characterizing only the warty crab. Among micro-elements, Ba, Cr, Cu, Li, Mn, Ni, and Pb showed extremely low concentrations and negligible among-species differences. Significant inter-specific differences were observed for Na, Sr, V, Ba, Cd and Zn; in particular, cadmium and zinc were characterized in the blue crab by concentrations significantly lower than in the other two species. The analysis of the available literature on the three species indicated a general lack of comparable information on their elemental composition. The need to implement extended elemental fingerprinting techniques for shellfish quality assessment is discussed, in view of other complementary profiling methods such as NMR-based metabolomics.

  13. 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.

  14. 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.

  15. Porcelain crabs from Brazil (Crustacea: Decapoda: Anomura: Porcellanidae).

    Science.gov (United States)

    Ferreira, Luciane Augusto De Azevedo; De Melo, Gustavo Augusto Schmidt

    2016-03-15

    Twenty species of porcelain crabs are reported on the basis of material collected from Brazilian coasts. Considering the lack of systematic studies comprehending the Brazilian porcellanids, the present work presents a review of the regional species based on the current taxonomic information. New records, information about variation between specimens and a taxonomic discussion are given for porcellanid crabs from Brazil.

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

    Science.gov (United States)

    Lindquist, Erin Stewart; Krauss, Ken W; Green, Peter T; O'Dowd, Dennis J; Sherman, Peter M; Smith, Thomas J

    2009-05-01

    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.

  17. 50 CFR 680.6 - Crab economic data report (EDR).

    Science.gov (United States)

    2010-10-01

    ... salaries for foremen, managers, and other employees not included in direct labor costs; and other vessel... employees not included in direct labor costs; and other vessel-specific costs (specify). (xii) BSAI crab...; food and provisions; other costs for direct crab labor; insurance deductible fees; re-packing costs...

  18. Mitigating by-catch of diamondback terrapins in crab pots

    Science.gov (United States)

    Hart, Kristen M.; Crowder, Larry B.

    2011-01-01

    Chronic by-catch of diamondback terrapins (Malaclemys terrapin) in blue crab (Callinectes sapidus) pots is a concern for terrapin conservation along the United States Atlantic and Gulf of Mexico coasts. Despite the availability of by-catch reduction devices (BRDs) for crab pots, adoption of BRDs has not been mandated and by-catch of terrapins continues. We conducted experimental fishing studies in North Carolina's year-round blue crab fishery from 2000 to 2004 to evaluate the ability of various BRDs to reduce terrapin by-catch without a concomitant reduction in the catch of blue crabs. In 4,822 crab pot days fished, we recorded only 21 terrapin captures. Estimated capture rates were 0.003 terrapins/pot per day in hard crab experimental fishing and 0.008 terrapins/pot per day in peeler experimental fishing. All terrapin captures occurred from April to mid-May within 321.4 m of the shoreline. Longer soak times produced more dead terrapins, with 4 live and 4 dead during hard crab experimental fishing and 11 live and 2 dead during peeler experimental fishing. The 4.0-cm BRDs in fall and 4.5-cm and 5.0-cm BRDs in spring reduced the catch of legal-sized male hard crabs by 26.6%, 21.2%, and 5.7%, respectively. Only the 5.0-cm BRDs did not significantly affect the catch of legal-sized hard male crabs. However, BRDs had no measurable effect on catch of target crabs in the peeler crab fishery. Our results identify 3 complementary and economically feasible tools for blue crab fishery managers to exclude terrapins from commercially fished crab pots in North Carolina: 1) gear modifications (e.g., BRDs); 2) distance-to-shore restrictions; and 3) time-of-year regulations. These measures combined could provide a reduction in terrapin by-catch of up to 95% without a significant reduction in target crab catch.

  19. Switching skeletons: hydrostatic support in molting crabs

    Science.gov (United States)

    Taylor, Jennifer R A.; Kier, William M.; Walker, I. D. (Principal Investigator)

    2003-01-01

    Skeletal support systems are essential for support, movement, muscular antagonism, and locomotion. Crustaceans shed their rigid exoskeleton at each molt yet are still capable of forceful movement. We hypothesize that the soft water-inflated body of newly molted crabs may rely on a hydrostatic skeleton, similar to that of worms and polyps. We measured internal hydrostatic pressure and the force exerted during claw adduction and observed a strong correlation between force and hydrostatic pressure, consistent with hydrostatic skeletal support. This alternation between the two basic skeletal types may be widespread among arthropods.

  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. 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.

  2. The porcelain crab transcriptome and PCAD, the porcelain crab microarray and sequence database.

    Directory of Open Access Journals (Sweden)

    Abderrahmane Tagmount

    Full Text Available 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 approximately 30K unique sequences (UniSeqs representing approximately 19K clusters were generated from approximately 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 66% 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

  3. 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...

  4. The Effects of Season and Sex on the Nutritional Quality of Muscle Types of Blue Crab Callinectes sapidus and Swimming Crab Portunus segnis

    Directory of Open Access Journals (Sweden)

    Deniz Ayas

    2016-05-01

    Full Text Available The effects of season and sex on the nutritional quality of muscle types (lump crab meatLCM, claw crab meat-CCM of swimming crab (Portunus segnis and blue crab (Callinectes sapidus were investigated. Carapace width, carapace length and total weight of both crab species were measured. High protein content in spring and low protein content in autumn were observed for both crab species. The levels of lipid content of both crab species were found to be similar. Higher lipid contents in spring and winter, lower lipid contents in summer and autumn for both sexes were found. Although both crab species contain small amounts of fat, they are good sources of n-3 PUFA content (especially EPA and DHA for all seasons regardless of sex and muscle types.

  5. Aggression and food resource competition between sympatric hermit crab species.

    Science.gov (United States)

    Tran, Mark V; O'Grady, Matthew; Colborn, Jeremiah; Van Ness, Kimberly; Hill, Richard W

    2014-01-01

    The vertical zonation patterns of intertidal organisms have been topics of interest to marine ecologists for many years, with interspecific food competition being implicated as a contributing factor to intertidal community organization. In this study, we used behavioral bioassays to examine the potential roles that interspecific aggression and food competition have on the structuring of intertidal hermit crab assemblages. We studied two ecologically similar, sympatric hermit crab species, Clibanarius digueti [1] and Paguristes perrieri [2], which occupy adjacent zones within the intertidal region of the Gulf of California. During the search phase of foraging, C. digueti showed higher frequencies of aggressive behaviors than P. perrieri. In competition assays, C. digueti gained increased access to food resources compared to P. perrieri. The results suggest that food competition may play an important role in structuring intertidal hermit crab assemblages, and that the zonation patterns of Gulf of California hermit crab species may be the result of geographical displacement by the dominant food competitor (C. digueti).

  6. 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.

  7. 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...

  8. 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).

  9. 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.

    The relationships observed between total carapace length with carapace width, carapace weight, telson length, body weight were found statistically significant (p < 0.05) in the male and female horseshoe crab, Tachypleus gigas (Muller). In females...

  10. 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).

  11. 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...

  12. New compact TEM-type deflecting and crabbing rf structure

    Directory of Open Access Journals (Sweden)

    J. R. Delayen

    2009-06-01

    Full Text Available A new type of rf structure for the deflection and crabbing of particle beams is presented. The structure is comprised of a number of parallel TEM resonant lines operating in opposing phase from each other. One of its advantages is its compactness compared to conventional crabbing cavities operating in the TM_{110} mode, thus allowing low frequency designs. This geometry would also be effective for the deflection of beams propagating at velocities substantially less than that of light.

  13. Burrowing and foraging activity of marsh crabs under different ...

    Science.gov (United States)

    New England salt marshes are susceptible to degradation and habitat loss as a result of increased periods of inundation as sea levels rise. Increased inundation may exacerbate marsh degradation that can result from crab burrowing and foraging. Most studies to date have focused on how crab burrowing and foraging can impact the dominant low marsh plant species, Spartina alterniflora. Here we used a mesocosm experiment to examine the relationship of foraging and burrowing activity in two dominant New England crab species, Sesarma reticulatum and Uca pugilator, and the combined effect of inundation, on the dominant high marsh plant species Spartina patens using a 3 × 2 factorial design with three crab treatments (Sesarma, Uca, control) at two levels of inundation (low, high). Plants were labeled with a nitrogen (N) stable isotope tracer to estimate plant consumption by the two crab species. At both levels of inundation, we found that S. reticulatum had a significant negative impact on both above- and below-ground biomass by physically clipping and uprooting the plants, whereas U. pugilator had no significant impact. Low inundation treatments for both crab species had significantly greater aboveground biomass than high inundation. Stable N isotope tracer levels were roughly the same for both S. reticulatum and U. pugilator tissue, suggesting that the impact of S. reticulatum on S. patens was not through consumption of the plants. Overall, our results suggest the pot

  14. A remarkable new crab-like hermit crab (Decapoda: Paguridae) from French Polynesia, with comments on carcinization in the Anomura.

    Science.gov (United States)

    Anker, Arthur; Paulay, Gustav

    2013-01-01

    Patagurus rex gen. et sp. nov., a deep-water pagurid hermit crab, is described and illustrated based on a single specimen dredged from 400 m off Moorea, Society Islands, French Polynesia. Patagurus is characterized by a subtriangular, vaulted, calcified carapace, with large, wing-like lateral processes, and is closely related to two other atypical pagurid genera, Porcellanopagurus Filhol, 1885 and Solitariopagurus Türkay, 1986. The broad, fully calcified carapace, calcified branchiostegites, as well as broad and rigidly articulated thoracic sternites make this remarkable animal one of the most crab-like hermit crabs. Patagurus rex carries small bivalve shells to protect its greatly reduced pleon. Carcinization pathways among asymmetrical hermit crabs and other anomurans are briefly reviewed and discussed.

  15. 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...

  16. 78 FR 21912 - Proposed Information Collection; Comment Request; Crab Rationalization (CR) Program: Annual Report

    Science.gov (United States)

    2013-04-12

    ... DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration Proposed Information Collection; Comment Request; Crab Rationalization (CR) Program: Annual Report AGENCY: National Oceanic and... for a new information collection. Since implementation of the Crab Rationalization (CR) Program (prior...

  17. Processing and products quality assessment lyophilized mangrove crab(Ucides cordatus)

    OpenAIRE

    LucÃlia KÃtia de Lima

    2015-01-01

    The mangrove crab, Ucides cordatus is one of the most shellfish produced in Brazil, but his consumption becomes scarce during closed season. This study aimed development of freezedried products of the mangrove crab stored at ambient temperature and analyze the effect of lyophilization in relation to physicalchemical, microbiological, nutritional and sensory characteristics. Two products were developed: a "freeze-dried crab meat" and "freeze-dried crab cone". The product quality wa...

  18. Design and prototyping of HL-LHC double quarter wave crab cavities for SPS test

    Energy Technology Data Exchange (ETDEWEB)

    Verdu-Andres, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Skaritka, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Wu, Q. [Brookhaven National Lab. (BNL), Upton, NY (United States); Xiao, B. [Brookhaven National Lab. (BNL), Upton, NY (United States); Belomestnykh, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., NY (United States); Ben-Zvi, I. [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., NY (United States); Alberty, L. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Artoos, K. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Calaga, R. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Capatina, O. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Capelli, T. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Carra, F. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Leuxe, R. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Kuder, N. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Zanoni, C. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Li, Z. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Ratti, A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2015-05-03

    The LHC high luminosity project envisages the use of the crabbing technique for increasing and levelling the LHC luminosity. Double Quarter Wave (DQW) resonators are compact cavities especially designed to meet the technical and performance requirements for LHC beam crabbing. Two DQW crab cavities are under fabrication and will be tested with beam in the Super Proton Synchrotron (SPS) at CERN by 2017. This paper describes the design and prototyping of the DQW crab cavities for the SPS test.

  19. [Distribution of Paragonimus (Digenea: Troglotrematidae) in Antioquia Province, Colombia, based on metacercariae counts in freshwater crabs].

    Science.gov (United States)

    Uruburu, Mónica; Granada, Mabel; Velásquez, Luz Elena

    2008-12-01

    Paragonimosis or lung fluke disease courses with signs similar to those seen in tuberculosis. The causative agent is a parasite of the genus Paragonimus (Digenea: Troglotrematidae). People become infected by ingesting raw or partially cooked crabs containing metacercariae. The first focus of human paragonimosis in Colombia was recorded in the county of Urrao, where two species of crabs infected with Paragonimus were found. In 2005, crabs with Paragonimus' metacercariae were captured near Medellín, western Colombia. This prompted a search for the parasite in other locations through its presence in the crabs. To establish the distribution of Paragonimus in Antioquia, we evaluated the presence of metacercaria in freshwater brachyuran crabs. From 2005 to 2007, crabs were captured in 13 counties of Antioquia. The crabs were relaxed and dissected to determine presence of trematodes and then to make the taxonomic identifications. From 52 crabs captured in 9 counties, 42 (80.8%) were found with Paragonimus metacercariae. The crabs were identified as Pseudothelphusidae in 2 genera--Hypolobocera and Strengeriana--and were assigned to four species. Three of the species were recorded for the first time as hosts of Paragonimus. A Paragonimus' distribution map was constructed for Antioquia; for the first time urban zones were included. Because of the high rate of infection, the handling and consumption of raw and poorly cooked crabs pose risk factors for human infection. Because crabs are affordable and provide means of easy diagnosis, crabs are targeted as primary agents of and diagnostic tools for paragonmosis.

  20. 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 ...

  1. 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

  2. 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...

  3. Systematics and biogeography of Cuban porcelain crabs (Decapoda: Anomura: Porcellanidae).

    Science.gov (United States)

    Diez, Yander L; Lira, Carlos

    2017-01-10

    Marine crustaceans are a well-known invertebrates group in Cuban waters, but some taxa are not well catalogued and the literature about them is scattered. In this work, we present the checklist of porcelain crabs of Cuban Archipelago, including the literature registers and unpublished author's data. A key to the identification of 8 genera and 23 species of the Cuban porcelain crabs is provided. Information about the local distribution of species is presented. In addition, we analyzed the porcelain crab faunal affinities between the ecoregions of the Cuban platform, Greater Antilles islands and the Tropical Northwestern Atlantic (TNA) province. For the first time, we record the presence of the monotypic genus Parapetrolisthes Haig in Cuba. On the Cuban platform, the highest similarities are between the Southcentral and Northwestern ecoregions (50%) and between Northcentral and Northeastern (40%). In the Greater Antilles, Cuba and Puerto Rico are the most similar (54%), but in general, the porcelain crab composition shows a high variation (e. g. 19% between Hispaniola and Puerto Rico). In the Tropical Northwestern Atlantic, five homogeneous groups of porcelain crab species are distinguished. Cuban fauna is most similar to that of Floridian, Western Caribbean and Southern Gulf of Mexico ecoregions. The decrease in species richness is evident from south to north in the TNA Province.

  4. 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.

  5. 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

  6. 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...

  7. 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...

  8. 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...

  9. 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...

  10. 77 FR 44216 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Science.gov (United States)

    2012-07-27

    ... the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab Rationalization Cost... Rationalization Program. This action is intended to provide holders of crab allocations with the fee percentage for the 2012/2013 crab fishing year. DATES: Fee liability payments made by the Crab Rationalization...

  11. 76 FR 43658 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Science.gov (United States)

    2011-07-21

    ... the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab Rationalization Cost... Rationalization Program. This action is intended to provide holders of crab allocations with the fee percentage... that must be submitted by July 31, 2012. DATES: The Crab Rationalization Program Registered Crab...

  12. 75 FR 43147 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Science.gov (United States)

    2010-07-23

    ... the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab Rationalization Cost... Rationalization Program. This action is intended to provide holders of crab allocations with the fee percentage... that must be submitted by July 31, 2011. DATES: The Crab Rationalization Program Registered Crab...

  13. 78 FR 46577 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Science.gov (United States)

    2013-08-01

    ... the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab Rationalization Cost... Rationalization Program. This action is intended to provide holders of crab allocations with the fee percentage... that must be submitted by July 31, 2014. DATES: The Crab Rationalization Program Registered Crab...

  14. 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

  15. Habitat selection and energetics of the fiddler crab ( Uca tangeri)

    Science.gov (United States)

    Klaassen, Marcel; Ens, Bruno J.

    We tried to unravel the possible links between the skewed predation risk in Uca tangeri (where large individuals are more at risk from avian predators) and size-dependent changes in the physiology and habitat choice of this fiddler crab species. Over a transect running from low to high in the tidal zone of a beach in Mauritania, the temperature profile at various depths in the substrate, the water-table level of seep water, salt concentration of seep water, depth of the aerobic level, operative temperatures on the surface, and size distribution of crabs were assessed. In addition, resting metabolic rates, Q 10 and thermal and starvation tolerances were estimated. Going from low to high in the tidal zone, crab size and burrow depth increased. At the preferred burrowing depth, microclimatological conditions appeared to be equally favourable at all sites. At the surface, conditions were more favourable low in the tidal zone, where also food availability is sufficient to enable small crabs to forage in the vicinity of their burrows. Large crabs have higher energy requirements and are thereby forced to forage in flocks low in the tidal zone where food is probably more abundant. Low in the tidal zone, digging deeply is impossible as the aerobic layer is rather thin. Large crabs prefer living high in the tidal zone as (1) deep burrows ensure better protection against predators, (2) more time is available for digging holes and (3) the substrate is better suited for reproduction. Energy reserves in late summer ensured an average of 34 days of survival. It is argued that the allotment of energy to growth must be considerable even in reproducing animals; the rewards of growth being the disproportional increase in reproductive output with size.

  16. Preliminary survey of a nemertean crab egg predator, Carcinonemertes, on its host crab, Callinectes arcuatus (Decapoda, Portunidae) from Golfo de Nicoya, Pacific Costa Rica

    Science.gov (United States)

    Okazaki, Robert K.; Wehrtmann, Ingo S.

    2014-01-01

    Abstract The possible presence of egg predators in brood masses of portunid crabs from Pacific Central America has not been studied yet. This survey reports the finding of a nemertean crab egg predator on the portunid crab, Callinectes arcuatus, from the Golfo de Nicoya, Pacific Costa Rica. Nemerteans were found in the egg masses of 26 out of the 74 crabs for a prevalence of 35%. The intensity (mean number of worms/ infected crab) was estimated to be 18 with a variance of 1–123 worms/infected crab. No nemerteans were observed either in the 19 Callinectes arcuatus from Golfo Dulce (southern Pacific coast) and the 10 Portunus asper from Herradura-Jaco (central Pacific coast). This nemertean is a member of the genus Carcinonemertes, which has been reported from the Caribbean coast of Panama. However, the encountered Carcinonemertes sp. is the first published finding and report from Costa Rica and Pacific Central America. PMID:25561848

  17. 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

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

    Science.gov (United States)

    Schnytzer, Yisrael; Giman, Yaniv; Karplus, Ilan; Achituv, Yair

    2017-01-01

    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.

  19. 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.

  20. 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.

  1. Quantification of the indirect effects of scallop dredge fisheries on a brown crab fishery.

    Science.gov (United States)

    Öndes, Fikret; Kaiser, Michel J; Murray, Lee G

    2016-08-01

    This study aimed to describe the characteristics of the by-catch of Cancer pagurus in king scallop dredges in the Isle of Man, and to determine the damage, immediate mortality and estimated mortality during fishing seasons associated with scallop dredges. Based on dredge surveys, spatial and seasonal variations were observed, with the highest number of crabs found off the west coast of the Isle of Man in the autumn when berried females crabs were most frequently caught. In general, female crabs comprised 84% of the catch. The damage levels of crabs was high with 45% of crabs recorded as crushed or dead or with severe damage, whilst 24% of crabs exhibited missing limbs. Estimates of the potential mortality associated with scallop dredging led to a lower and upper estimate of possible crab by-catch mortality of 15t and 24t respectively which represented 3.0-4.8% of the commercial landings of brown crab for the Isle of Man. Heaviest mortalities of crabs occurred in autumn to the west of the Isle of Man when female berried crabs move offshore into deeper water. The use of a temporary and spatially restricted scallop dredging closure could provide a simple solution to mitigate additional crab mortality in the event that scallop dredging increased beyond current levels in the future. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. 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.

  3. Distribution patterns of the ghost crab Ocypode cursor on sandy ...

    African Journals Online (AJOL)

    The spatial distribution of the ghost crab Ocypode cursor was determined for beaches on eastern Boa Vista Island, Cabo Verde Archipelago. The main objectives were to analyse the across-shore distribution by means of burrow counts and to identify preferential zones and spatial segregation. Six beaches were investigated ...

  4. Haematological and Serum Biochemical Profile of the Blue Crab ...

    African Journals Online (AJOL)

    Haematology and serum biochemistry of the crab, Callinectes amnicola from Epe and Lagos Lagoon in southwest Nigeria were investigated from March –August, 2013. Haemocyte samples were analyzed for haematological and biochemical parameters. The Total Haemocyte count (THC) of C. amnicola from Epe and ...

  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 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)

  7. 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 ...

  8. Size at Sexual Maturity in the Red Mangrove Crab Neosarmatium ...

    African Journals Online (AJOL)

    The sesarmid crab Neosarmatium meinertiis one of the most abundant species inhabiting the upper mangrove areas of many East African mangrove forests. However, several aspects concerning its reproduction are scarcely known. In this study, sexual maturity of N. meinerti is investigated. Samples were obtained during ...

  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. 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

  11. Breeding biology of the intertidal sand crab, Emerita (Decapoda: Anomura).

    Science.gov (United States)

    Subramoniam, T; Gunamalai, V

    2003-01-01

    Emerita is a burrowing mole crab or sand crab, adapted to life in wave-washed sandy beaches of temperate and tropical seas. The reproductive biology of this anomuran crab presents several peculiarities, all contributing to its adaptation to this harsh environmental niche. We discuss the following aspects: 1) sex ratio and size at sexual maturity, 2) neoteny and protandric hermaphroditism, 3) mating behaviour and sperm transfer strategy, 4) synchronisation of moulting and reproduction, 5) environmental impact on reproductive cycle and egg production, 6) biochemistry of yolk utilisation and energetics, 7) larval development, dispersal and settlement and 8) the value of Emerita as indicator species. These aspects are discussed in the light of the life history pattern, comprising a sedentary adult and pelagic larval phases. The successful colonisation of the physically challenging habitat of the sandy beach by Emerita is attributable largely to reproductive strategy and the larval developmental and recruitment pattern. Sensitivity to changing environmental conditions, including pollution, make this intertidal crab an indicator species for monitoring anthropogenic impact.

  12. Substrate use and selection in sympatric intertidal hermit crab species

    Directory of Open Access Journals (Sweden)

    TURRA A.

    2002-01-01

    Full Text Available Coexisting hermit crabs may competitively interact for shells and microhabitats, mainly when shell availability is habitat-related. Three species of Clibanarius (C. antillensis, C. sclopetarius, and C. vittatus coexist in the intertidal region of Pernambuco Islet, Araçá Region, São Sebastião Channel, southeastern Brazil. This study evaluated crab preferences for four substrate types used by these species in nature (rocky shore, pebbles, sand, and mud in allopatric (single species and sympatric (three species treatments in simulations of high tide and low tide. The substrate preference of the three hermit crabs did not vary between low and high tide situations. At low tide the crabs either moved into holes in the highly complex rocky substrate or buried themselves in mud. Substrate selection may explain the patterns of substrate use in nature only for C. vittatus. Clibanarius antillensis and C. sclopetarius showed closer similarities in the pattern of substrate selection in the sympatric treatment with the substrate use in nature than in allopatric treatment, indicating a positive influence (dependence of the presence of one species on the presence of another. Use of sub-optimal substrates, mainly by C. antillensis, may be caused by other factors such as its low desiccation tolerances. If competition for space takes place among these species, it would be more intense between C. sclopetarius and C. vittatus given their higher overlap in substrate preference than between them and C. antillensis.

  13. Substrate use and selection in sympatric intertidal hermit crab species

    Directory of Open Access Journals (Sweden)

    A. TURRA

    Full Text Available Coexisting hermit crabs may competitively interact for shells and microhabitats, mainly when shell availability is habitat-related. Three species of Clibanarius (C. antillensis, C. sclopetarius, and C. vittatus coexist in the intertidal region of Pernambuco Islet, Araçá Region, São Sebastião Channel, southeastern Brazil. This study evaluated crab preferences for four substrate types used by these species in nature (rocky shore, pebbles, sand, and mud in allopatric (single species and sympatric (three species treatments in simulations of high tide and low tide. The substrate preference of the three hermit crabs did not vary between low and high tide situations. At low tide the crabs either moved into holes in the highly complex rocky substrate or buried themselves in mud. Substrate selection may explain the patterns of substrate use in nature only for C. vittatus. Clibanarius antillensis and C. sclopetarius showed closer similarities in the pattern of substrate selection in the sympatric treatment with the substrate use in nature than in allopatric treatment, indicating a positive influence (dependence of the presence of one species on the presence of another. Use of sub-optimal substrates, mainly by C. antillensis, may be caused by other factors such as its low desiccation tolerances. If competition for space takes place among these species, it would be more intense between C. sclopetarius and C. vittatus given their higher overlap in substrate preference than between them and C. antillensis.

  14. Hermit Crabs (Decapoda: Anomura: Paguridea) from the Seychelles

    NARCIS (Netherlands)

    McLaughlin, P.A.; Hogarth, P.J.

    1998-01-01

    A report on the hermit crabs collected during the Netherlands Seychelles Expedition, 1992-1993, supplemented by materials collected for Enterprise Oil and examined by one of the authors. Twentyseven species, representing three families, are recognized, including one new genus and four new species.

  15. 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.

  16. 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

  17. 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 ...

  18. 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…

  19. The abundance and composition of crabs (Decapoda) in Uta Ewa ...

    African Journals Online (AJOL)

    The results of the physicochemical parameters were within limits of the National Environmental Standards and Regulations Enforcement Agencies for aquatic life. A total of 107 crabs were collected from the two sampling stations. Goniopsis pelii was the most abundant in Station 1 accounting for 57.9%, followed by ...

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

    African Journals Online (AJOL)

    STORAGESEVER

    2009-03-20

    Mar 20, 2009 ... divergence between these two groups (Okinawa and main islands of Japan) is equivalent to the genetic distance between congeneric species. Our results failed to demonstrate significant geographical structure in main islands of Japan, indicating that populations of Japanese mitten crab are capable of.

  1. Occurrence and Toxicity of Hydrocarbon Residues in Crab ...

    African Journals Online (AJOL)

    To elucidate seasonal changes in hydrocarbons including polycyclic aromatic hydrocarbons (PAHs) due to oil spill, tissues of blue crab (Callinectes sapidus) were investigated. Total petroleum hydrocarbons (n-alkanes) concentrations ranged from 0.17-0.32ìg/gdw and 0.28-0.62ìg/gdw during the dry and wet seasons ...

  2. 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

  3. 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.

  4. Food Habits of the Blue Swimming Crab Portunus pelagicus along ...

    African Journals Online (AJOL)

    43: 225–240. Sumpton, W.D. & Smith, G.S. (1990) Effect of temperature on the emergence, activity and feeding of male and female sand crabs (Portunus pelagicus). Aust. J. Mar. Freshwat. Res. 41: 545–. 550. Underwood, A.J. (1981) Techniques of analysis of variance in experimental marine biology and ecology. Oceanogr.

  5. 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.

    or therapeutic drugs against bacterial infections. A lectin from the Scylla serrata crab hemolymph has been isolated and purified by affinity column chromatography and preparative electrophoresis [7]. Based on studies of the health-promoting activities... bacterial, fungal and multi drug resistant bacterial strains viz, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella typhi, Shigella flexineri, Klebsiella sp., Vibrio cholerae, Aspergillus fumigatus, Rhodotorula sp., Candida...

  6. Estimated Entrainment of Dungeness Crab During Dredging For The Columbia River Channel Improvement Project

    Energy Technology Data Exchange (ETDEWEB)

    Pearson, Walter H.; Williams, Greg D.; Skalski, John R.

    2002-12-01

    The studies reported here focus on issues regarding the entrainment of Dungeness crab related to the proposed Columbia River Channel Improvement Project and provided direct measurements of crab entrainment rates at three locations (Desdomona Shoals, Upper Sands, and Miller Sands) from RM4 to RM24 during summer 2002. Entrainment rates for all age classes of crabs ranged from zero at Miller Sands to 0.224 crabs per cy at Desdemona Shoals in June 2002. The overall entrainment rate at Desdomona Shoals in September was 0.120 crabs per cy. A modified Dredge Impact Model (DIM) used the summer 2002 entrainment rates to project crab entrainment and adult equivalent loss and loss to the fishery for the Channel Improvement Project. To improve the projections, entrainment data from Flavel Bar is needed. The literature, analyses of salinity intrusion scenarios, and the summer 2002 site-specific data on entrainment and salinity all indicate that bottom salinity influences crab distribution and entrainment, especially at lower salinities. It is now clear from field measurements of entrainment rates and salinity during a period of low river flow (90-150 Kcfs) and high salinity intrusion that entrainment rates are zero where bottom salinity is less than 16 o/oo most of the time. Further, entrainment rates of 2+ and older crab fall with decreasing salinity in a clear and consistent manner. More elaboration of the crab distribution- salinity model, especially concerning salinity and the movements of 1+ crab, is needed.

  7. Distribution and shell selection by two hermit crabs in different habitats on Egyptian Red Sea Coast

    Science.gov (United States)

    El-Kareem Ismail, Tarek Gad

    2010-05-01

    The present work aims to assess the spatial distribution, analyze shell utilization, shell fitness and determine the effect of coexistence of two hermit crabs Calcinus latens and Clibanarius signatus on used shell resources in various habitats on the Red Sea Coast. Also, to determine the choice of shells and investigate the shell species preference of C. latens and C. signatus in the laboratory. The hermit crabs C. latens and C. signatus were found to occupy shells of 39 gastropod species. The most commonly occupied gastropod shells are those belonging to genera Strombus, Nerita, Cerithium and Planaxis. The results showed that crab individuals utilized mainly the shell with elongate aperture. Laboratory experiments showed that two crab species preferred shells of Strombus followed by Cerithium and Nerita when offered shells of nearly similar size (optimal). Crab individuals showed a significant preference for optimal sized shells when given suboptimal shells as an alternative choice. Also, the hermit crabs avoid damaged shells when given a choice of optimal sized damaged shell and optimal sized intact one. In addition, two hermit crab species chose shells of smaller than optimal size when given a choice of damaged optimal sized shells and smaller intact ones. On the other hand, field observations showed that most crab individuals lived in adequate sized shells. The present data conclude that shell selection by hermit crabs C. latens and C. signatus depends mostly on shell internal volume, shell quality and shell aperture size than other factors, because they provide a maximum protection for hermit crabs.

  8. Comparative brain architecture of the European shore crab Carcinus maenas (Brachyura) and the common hermit crab Pagurus bernhardus (Anomura) with notes on other marine hermit crabs.

    Science.gov (United States)

    Krieger, Jakob; Sombke, Andy; Seefluth, Florian; Kenning, Matthes; Hansson, Bill S; Harzsch, Steffen

    2012-04-01

    The European shore crab Carcinus maenas and the common hermit crab Pagurus bernhardus are members of the sister taxa Brachyura and Anomura (together forming the taxon Meiura) respectively. Both species share similar coastal marine habitats and thus are confronted with similar environmental conditions. This study sets out to explore variations of general brain architecture of species that live in seemingly similar habitats but belong to different major malacostracan taxa and to understand possible differences of sensory systems and related brain compartments. We examined the brains of Carcinus maenas, Pagurus bernhardus, and three other hermit crab species with immunohistochemistry against tyrosinated tubulin, f-actin, synaptic proteins, RF-amides and allatostatin. Our comparison showed that their optic neuropils within the eyestalks display strong resemblance in gross morphology as well as in detailed organization, suggesting a rather similar potential of processing visual input. Besides the well-developed visual system, the olfactory neuropils are distinct components in the brain of both C. maenas and P. bernhardus as well as the other hermit crabs, suggesting that close integration of olfactory and visual information may be useful in turbid marine environments with low visibility, as is typical for many habitats such as, e.g., the Baltic and the North Sea. Comparing the shape of the olfactory glomeruli in the anomurans showed some variations, ranging from a wedge shape to an elongate morphology. Furthermore, the tritocerebrum and the organization of the second antennae associated with the tritocerebrum seem to differ markedly in C. maenas and P. bernhardus, indicating better mechanosensory abilities in the latter close to those of other Decapoda with long second antennae, such as Astacida, Homarida, or Achelata. This aspect may also represent an adaptation to the "hermit lifestyle" in which competition for shells is a major aspect of their life history. The shore

  9. Effect of daily chlorhexidine bathing on acquisition of carbapenem-resistant Acinetobacter baumannii (CRAB) in the medical intensive care unit with CRAB endemicity.

    Science.gov (United States)

    Chung, Yun Kyung; Kim, Jae-Seok; Lee, Seung Soon; Lee, Jeong-A; Kim, Han-Sung; Shin, Kyong-Sok; Park, Eun Young; Kang, Bog Soun; Lee, Hee Jung; Kang, Hyun Joo

    2015-11-01

    There is insufficient evidence for daily chlorhexidine bathing to reduce nosocomial spread of carbapenem-resistant Acinetobacter baumannii (CRAB) in endemic situations. An interrupted time series study was performed to evaluate the effect of daily chlorhexidine bathing on the acquisition of CRAB in a medical intensive care unit (ICU) with CRAB endemicity. There was a 14-month control period and 12-month chlorhexidine bathing period. Segmented Poisson regression analysis was performed to assess the impact of chlorhexidine bathing on the level and trend of the series of prevalence rates and incidence density. Also, chlorhexidine susceptibility testing was performed on CRAB isolates collected during the chlorhexidine bathing period. There was a 51.8% reduction of CRAB acquisition rates after an introduction of daily chlorhexidine bathing (44.0 vs 21.2 cases/1,000 at-risk patient days, P chlorhexidine against a total of 98 CRAB isolates ranged from 8-64 μg/mL. Daily chlorhexidine bathing significantly reduces the acquisition of CRAB in a medical ICU with CRAB endemicity. Copyright © 2015 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

  10. 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...

  11. Crabs mediate interactions between native and invasive salt marsh plants: a mesocosm study.

    Science.gov (United States)

    Zhang, Xiao-Dong; Jia, Xin; Chen, Yang-Yun; Shao, Jun-Jiong; Wu, Xin-Ru; Shang, Lei; Li, Bo

    2013-01-01

    Soil disturbance has been widely recognized as an important factor influencing the structure and dynamics of plant communities. Although soil reworkers were shown to increase habitat complexity and raise the risk of plant invasion, their role in regulating the interactions between native and invasive species remains unclear. We proposed that crab activities, via improving soil nitrogen availability, may indirectly affect the interactions between invasive Spartina alterniflora and native Phragmites australis and Scirpus mariqueter in salt marsh ecosystems. We conducted a two-year mesocosm experiment consisting of five species combinations, i.e., monocultures of three species and pair-wise mixtures of invasive and native species, with crabs being either present or absent for each combination. We found that crabs could mitigate soil nitrogen depletion in the mesocosm over the two years. Plant performance of all species, at both the ramet-level (height and biomass per ramet) and plot-level (density, total above- and belowground biomass), were promoted by crab activities. These plants responded to crab disturbance primarily by clonal propagation, as plot-level performance was more sensitive to crabs than ramet-level. Moreover, crab activities altered the competition between Spartina and native plants in favor of the former, since Spartina was more promoted than native plants by crab activities. Our results suggested that crab activities may increase the competition ability of Spartina over native Phragmites and Scirpus through alleviating soil nitrogen limitation.

  12. 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.

  13. Diet selectivity of juvenile blue crabs (Callinectes sapidus) in Chesapeake Bay.

    Science.gov (United States)

    Seitz, Rochelle D; Knick, Kathleen E; Westphal, Miranda

    2011-10-01

    Shallow coves in Chesapeake Bay have abundant food and serve as nursery grounds for juvenile blue crabs. In this study, we examined the relationships between the diet of very small (4-40 mm CW) juvenile blue crabs and the benthic infauna in shallow, unvegetated nursery coves. We compared infauna in benthic samples with gut contents of juvenile blue crabs from six shallow coves in each of two sub-estuaries (Rappahannock and York Rivers) in Chesapeake Bay, Virginia, USA. Benthic communities differed depending on river and location, with abundant clams in upriver regions and abundant polychaetes in downriver regions. Juvenile crabs, like adults, appeared to be opportunistic feeders, with gut contents including clams, amphipods, polychaetes, small crustaceans, plant matter, and detritus. There was a positive relationship between polychaetes in the benthic samples and in crab guts, suggesting that juvenile crabs are opportunistic feeders on polychaetes in the benthos. Moreover, Ivlev's electivity index and foraging ratio showed that clams and polychaetes were selectively eaten at all locations. Alternatively, crabs selectively rejected amphipods. Crab densities corresponded positively with polychaete densities, which suggests that there may be bottom-up control of crab distributions and that food resources are important in nursery habitats.

  14. Oxygen and carbon dioxide sensitivity of ventilation in amphibious crabs, Cardisoma guanhumi, breathing air and water.

    Science.gov (United States)

    Gannon, Andrew T; Henry, Raymond P

    2004-05-01

    Amphibious crabs, Cardisoma guanhumi, were acclimated to breathing either air or water and exposed to altered levels of oxygen and/or carbon dioxide in the medium. Hypercapnia (22, 36 and 73 torr CO(2)) stimulated a significant hypercapnic ventilatory response (HCVR) in both groups of crabs, with a much greater effect on scaphognathite frequency (Deltaf(SC)=+700%) in air-breathing crabs than water-breathing crabs (Deltaf(SC)=+100%). In contrast, hyperoxia induced significant hypoventilation in both sets of crabs. However, simultaneous hyperoxia and hypercapnia triggered a greater than 10-fold increase in f(SC) in air-breathing crabs but no change in water-breathing crabs. For water-breathing crabs hypoxia simultaneous with hypercapnia triggered the same response as hypoxia alone-bradycardia (-50%), and a significant increase in f(SC) at moderate exposures but not at the more extreme levels. The response of air-breathing crabs to hypoxia concurrent with hypercapnia was proportionally closer to the response to hypercapnia alone than to hypoxia. Thus, C. guanhumi were more sensitive to ambient CO(2) than O(2) when breathing air, characteristic of fully terrestrial species, and more sensitive to ambient O(2) when breathing water, characteristic of fully aquatic species. C. guanhumi possesses both an O(2)- and a CO(2)-based ventilatory drive whether breathing air or water, but the relative importance switches when the respiratory medium is altered.

  15. Crabs mediate interactions between native and invasive salt marsh plants: a mesocosm study.

    Directory of Open Access Journals (Sweden)

    Xiao-Dong Zhang

    Full Text Available Soil disturbance has been widely recognized as an important factor influencing the structure and dynamics of plant communities. Although soil reworkers were shown to increase habitat complexity and raise the risk of plant invasion, their role in regulating the interactions between native and invasive species remains unclear. We proposed that crab activities, via improving soil nitrogen availability, may indirectly affect the interactions between invasive Spartina alterniflora and native Phragmites australis and Scirpus mariqueter in salt marsh ecosystems. We conducted a two-year mesocosm experiment consisting of five species combinations, i.e., monocultures of three species and pair-wise mixtures of invasive and native species, with crabs being either present or absent for each combination. We found that crabs could mitigate soil nitrogen depletion in the mesocosm over the two years. Plant performance of all species, at both the ramet-level (height and biomass per ramet and plot-level (density, total above- and belowground biomass, were promoted by crab activities. These plants responded to crab disturbance primarily by clonal propagation, as plot-level performance was more sensitive to crabs than ramet-level. Moreover, crab activities altered the competition between Spartina and native plants in favor of the former, since Spartina was more promoted than native plants by crab activities. Our results suggested that crab activities may increase the competition ability of Spartina over native Phragmites and Scirpus through alleviating soil nitrogen limitation.

  16. 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.

  17. Hermit crabs in the diet of Pigeon Guillemots at Kachemak Bay, Alaska

    Science.gov (United States)

    Litzow, Michael A.; Piatt, John F.; Figurski, Jared D.

    1998-01-01

    Guillemots (Cepphus spp.) feed their chicks a diet that is almost exclusively fish. We observed Pigeon Guillemots (C. columba) at two colonies in Alaska where hermit crabs (Crustacea: Anomura) were a major part of the diet for some nestlings. Hermit crabs were delivered to three of five observed nests at one colony, comprised between 2% and 22% of the items delivered at those nests, and were the second most common food type at one nest. Hermit crabs may be an attractive prey item when lipid-rich forage fish are scarce, and crabs living in gastropod shells that have been softened by encrustations of Suberites sponges may be vulnerable to guillemot predation.

  18. Studies on the ecology and behaviour of the ghost crab, Ocypode cursor (L. in northern Cyprus

    Directory of Open Access Journals (Sweden)

    P. H. Strachan

    1999-03-01

    Full Text Available Aspects of the ecology and behaviour of Ocypode cursor were studied on the beaches of Northern Cyprus. The crabs were widely distributed around the north coast of the island, occurring on 68 of the 77 sandy beaches investigated. At the main study beach at Alagadi, crabs occupied a band approximately 12 m wide; starting approximately 3 m horizontally from the edge of the sea (tidal fluctuation was minimal. Most small burrows occurred near to the sea, with the burrows of larger crabs predominating higher up the beach. Burrow numbers varied during the summer which was mainly attributable to variations in the numbers of burrows of juveniles. The sex ratio of emergent crabs also varied during the summer, possibly reflecting burrow oriented behaviour of reproductive females. There were strong correlations between burrow diameters and carapace lengths of the occupant crabs. There was a positive correlation between the presence of crab burrows and the number of people using sections of beach. The crabs were principally nocturnal, benefitting from food discarded by tourists. They also scavenged animal carcasses and were active predators of turtle eggs and hatchlings. Crab burrows usually had a single opening oriented towards the sea and those cast were L- or J-shaped. Burrows did not penetrate to the water table. The water content of the sand at the bottom of burrows was around 14 % by weight. Their burrows in the well-sorted sand provided the crabs with a thermally stable environment.

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

    Science.gov (United States)

    Hunter, Ewan; Eaton, Derek; Stewart, Christie; Lawler, Andrew; Smith, Michael T

    2013-01-01

    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.

  20. A horseshoe crab receptor structurally related to Drosophila Toll.

    Science.gov (United States)

    Inamori, K; Koori, K; Mishima, C; Muta, T; Kawabata, S

    2000-01-01

    Innate immunity against microbial pathogens relies on the pattern recognition of cell wall components on invading microbes. Recent evidence has shown that a mammalian Toll-like receptor (TLR) is activated by bacterial lipopolysaccharides (LPS). The innate immunity in invertebrates is also triggered by LPS, as seen in the hemolymph coagulation in horseshoe crab. We report the cloning of a TLR from the Japanese horseshoe crab Tachypleus tridentatus. A cDNA coding for Tachypleus Toll was isolated from a hemocyte cDNA library and the open reading frame codes for a proprotein including a signal sequence. Like Drosophila Toll, Tachypleus Toll is a type I transmembrane protein with an extracellular domain consisting of two leucine-rich repeats flanked by two cystein-rich clusters and a cytoplasmic domain exhibiting striking similarity with the cytoplasmic domain of interleukin-1 receptor. Tachypleus Toll is most similar to Drosophila Toll in the domain architecture and the overall length.

  1. Shell selection of hermit crabs is influenced by fluid drag

    Science.gov (United States)

    Casillas, Barbara; Ledesma, Rene; Alcaraz, Guillermina; Zenit, Roberto

    2010-11-01

    The flow around gastropod shells used by hermit crabs (Calcinus californiensis) was visualized experimentally. These crabs choose their shells according to many factors; we found that the choice of shell (shape and weight) is directly related to the drag caused over them by the exposure to wave action. Tests were conducted in a wind tunnel to investigate flow differences for shells of various shapes. A particle image velocimetry (PIV) system was used to visualize the flow field. The images above show the flow field around two types of shells (Thais speciosa and Nerita scabircosta) for Reynolds numbers of O(10^5). Using a control volume analysis, the drag coefficient was inferred. Several shell geometries, orientations and mean flow velocities were tested. In this talk, the flow and drag force will be shown for the different arrangements. A discussion of the relation between drag and shape will be presented.

  2. 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...

  3. LHC crab cavity specifications milestone: M10.3.1

    CERN Document Server

    Calaga, R; Jensen, E; McIntosh, P; Shaposhnikova, E; Tuckmantel, J; Zimmermann, F

    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 arise fro...

  4. Susceptibilidad in vitro a infección por Leishmania y sensibilidad a medicamentos difiere según tipo de macrófagos The susceptibility to infection by Leishmania panamensis and the sensitivity to drugs differ according to the macrophage type

    Directory of Open Access Journals (Sweden)

    Carol V. Mesa

    2010-12-01

    Full Text Available Introducción: Los sistemas in vitro son útiles en la evaluación de compuestos con actividad biológica, permitiendo por ejemplo, determinar el potencial citotóxico y leishmanicida de un compuesto. Objetivo: Identificar el tipo de célula mamífera que permita una óptima infección in vitro por Leishmania y que constituya el sistema adecuado para el tamizaje in vitro de compuestos con actividad anti-Leishmania. Métodos: La susceptibilidad de las células a infección por L. panamensis se evalúo según la Concentración Infectiva 50 determinada por microscopía de luz y citometría de flujo; la supervivencia intracelular de los amastigotes se evaluó por microscopía de fluorescencia y la sensibilidad de las células a anfotericina B y antimoniato de meglumina se evalúo por espectrofotometría. Resultados: Los cultivos primarios son más susceptibles a la infección por L. panamensis in vitro. Sin embargo, la supervivencia intracelular del parásito fue mejor en U-937. Por su parte, la sensibilidad de las células a anfotericina B y antimoniato de meglumina vario según el tipo de célula. Conclusión: Las células U-937 son las adecuadas para la infección por Leishmania porque: a presentan crecimiento ilimitado y se les puede inducir transformación a macrófagos. b la susceptibilidad a la infección por Leishmania es similar a la observada en cultivos primarios de macrófagos y c permiten mayor supervivencia de los amastigotes luego de la infección. Adicionalmente, las células U-937 son menos sensibles a la acción de los fármacos comúnmente utilizados como control en la detección de compuestos con actividad leishmanicida. Salud UIS 2010; 42: 200-211Introduction: In vitro systems are useful in the evaluation of compounds with biological activity determining the cytotoxic and leishmanicidal activity of the candidates. Objective: To identify the mammalian cell that allows the optimal in vitro infection by Leishmania and therefore

  5. First Test Results of the 4-ROD Crab Cavity

    CERN Document Server

    Ambattu, P; Burt, G; Calaga, R; Capatina, O; Calatroni, S; Ciapala, E; Doherty, D; Ferreira, L; Jensen, E; Hall, B; Lingwood, C; Maesen, P; Mongelluzzo, A; Renaglia, T; Therasse, M

    2013-01-01

    The first compact prototype crab cavity with the 4rod geometry has undergone surface treatment and cold testing. Due to the complex geometry and unique fabrication procedure, RF validation of the field at beyond the nominal operating voltage at a sufficiently high Q0 is an important pre-requisite. Preliminary results of the first cold tests are presented along with cavity performance at different stages of the cavity processing is described.

  6. 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.

  7. 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.

  8. 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

  9. Observation and Spectral Measurements of the Crab Nebula with Milagro

    Science.gov (United States)

    Abdo, A. A.; Allen, B. T.; Aune, T.; Benbow, W.; Berley, D.; Chen, C.; Christopher, G. E.; DeYoung, T.; Dingus, B. L.; Falcone, A.; hide

    2011-01-01

    The Crab Nebula was detected with the Milagro experiment at a statistical significance of 17 standard deviations over the lifetime of the experiment. The experiment was sensitive to approximately 100 GeV - 100 TeV gamma ray air showers by observing the particle footprint reaching the ground. The fraction of detectors recording signals from photons at the ground is a suitable proxy for the energy of the primary particle and has been used to measure the photon energy spectrum of the Crab Nebula between 1 and 100 TeV. The TeV emission is believed to be caused by inverse-Compton up-scattering scattering of ambient photons by an energetic electron population. The location of a Te V steepening or cutoff in the energy spectrum reveals important details about the underlying electron population. We describe the experiment and the technique for distinguishing gamma-ray events from the much more-abundant hadronic events. We describe the calculation of the significance of the excess from the Crab and how the energy spectrum is fit.

  10. a Surprise from the Pulsar in the Crab Nebula

    Science.gov (United States)

    1995-11-01

    New observations of the spectrum of the rapidly spinning neutron star (the `pulsar') in the Crab Nebula have been carried out with the ESO 3.5-metre New Technology Telescope (NTT) by a group of Italian astronomers [1]. Because of greatly improved spectral resolution which allows to register even very fine details in the pulsar's spectrum, they are able to determine for the first time with high accuracy the overall dependance of the emission on wavelength, i.e. the `shape' of the spectrum. Quite unexpectedly, they also detect a hitherto unknown 100 A (10 nm) broad `absorption dip', which can be securely attributed to the pulsar. These results open an exciting new window for the study of the extreme physical processes close to a pulsar. The Nature of Pulsars It is estimated that there may be as many as 100 million neutron stars in our Galaxy. A neutron star is the superdense remnant of the extremely violent supernova explosion that occurs at the end of the life of a comparatively massive star. In fact, all stars that are more than about 6 times heavier than the Sun are believed to end their lives as supernovae. During the explosion, the central core of the dying star collapses in a few milliseconds and the matter at the centre is compressed to a density comparable to that of an atomic nucleus. Due to the enormous inward pressure, the atomic particles are squeezed together into a kind of neutron jam. The outcome is the formation of a neutron star with a diameter of 10-15 kilometres, weighing as much as the Sun. In accordance with the physical law that implies that the rotation momentum of the exploding star must be conserved, newborn neutron stars will rotate very rapidly around their axis, in some cases as fast as 100 times per second. In the same way, the new neutron star is expected to possess a strong magnetic field. Of these myriads of neutron stars, about 700 have been observed to emit radio pulses (hence the name `pulsar'). A few of these can also be detected

  11. 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...

  12. 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.

  13. 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

  14. 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.

  15. 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 ...

  16. 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. PMID:23166774

  17. Dioxins, PCBs and heavy metals in Chinese mitten crabs from Dutch rivers and lakes.

    Science.gov (United States)

    Hoogenboom, Ron L A P; Kotterman, Michiel J J; Hoek-van Nieuwenhuizen, Marion; van der Lee, Martijn K; Mennes, Wim C; Jeurissen, Suzanne M F; van Leeuwen, Stefan P J

    2015-03-01

    Chinese mitten crab is an invasive species in many European rivers and lakes. Data from the UK indicated high levels of dioxins and PCBs, in particular in the brown meat in the body. This was confirmed by studies in the Netherlands, showing average levels of dioxins and PCBs in the meat in the body of 43 pg TEQ g(-1) ww in crabs caught in the large rivers. Levels in crab of lakes in the Northern part of the Netherlands were on average 3.7-fold lower. Consumption of crabs from polluted areas results in a relatively high dose of dioxins and dl-PCBs and could significantly increase the intake above the TWI. However, in general consumption of these crabs is low, even in the Asian sub-population in the Netherlands. Cadmium and lead levels were higher in crabs from contaminated areas, but for mercury and arsenic there was no clear difference. Consumption of crabs would not result in significant risks for cadmium and mercury. For lead the daily intake could be raised above the BMDL01 for neurodevelopmental toxicity, but this would only occur on a limited number of days. For arsenic the exposure would exceed the lower end of the BMDL01 values for certain cancers, but again, the infrequent consumption by most consumers reduces this risk. Furthermore, speciation showed that most arsenic in crabs was probably not a toxic inorganic form, but likely to be in an organic form. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. 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.

  19. 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

  20. 50 CFR Table 1 to Part 680 - Crab Rationalization (CR) Fisheries

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Crab Rationalization (CR) Fisheries 1 Table 1 to Part 680 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND... ZONE OFF ALASKA Pt. 680, Table 1 Table 1 to Part 680—Crab Rationalization (CR) Fisheries Fishery Code...

  1. On the misidentification of a common sandy beach crab belonging to ...

    African Journals Online (AJOL)

    1992-07-09

    Jul 9, 1992 ... DU PREEZ, H.H. & MCLACHLAN, A. 1984c. Biology of the three-spot swimming crab, Ovalipes puncta/us (De Haan) D. Growth and moulting. Crustaceana. 47: 113-120. DU PREFZ, H.H. & MCLACHLAN, A. 1984d. Biology of the three-spot swimming crab, Ovalipes puncta/us (De Haan) DI. Reproduction ...

  2. Entrainment of Dungeness Crab in the Desdemona Shoals Reach of the Lower Columbia River Navigation Channel

    Energy Technology Data Exchange (ETDEWEB)

    Pearson, Walter H.; Kohn, Nancy P.; Skalski, J. R.

    2006-09-30

    Proposed dredging of the Columbia River has raised concerns about related impacts on Dungeness crab in the Columbia River Estuary (CRE). This study follows two major efforts, sponsored by the Portland District of the U. S. Army Corps of Engineers (USACE) to quantify the number of crabs entrained by a hopper dredge working in the CRE. From June 2002 through September 2002, Pacific Northwest National Laboratory (PNNL) conducted direct measurements of crab entrainment in the CRE from the mouth of the Columbia River (MCR, river mile -3 to +3) upriver as far as Miller Sands (river mile 21 to 24). These studies constituted a major step in quantifying crab entrainment in the CRE, and allowed statistically bounded projections of adult equivalent loss (AEL) for Dungeness crab populations under a range of future construction dredging and maintenance dredging scenarios (Pearson et al. 2002, 2003). In 2004, PNNL performed additional measurements to improve estimates of crab entrainment at Desdemona Shoals and at Flavel Bar, a reach near Astoria that had not been adequately sampled in 2002 (Figure 1). The 2004 data were used to update the crab loss projections for channel construction to 43 ft MLLW. In addition, a correlation between bottom salinity and adult (age 2+ and 3+, >100 mm carapace width) crab entrainment was developed using 2002 data, and elaborated upon with the 2004 data. This crab salinity model was applied to forecasting seasonal (monthly) entrainment rates and AEL using seasonal variations in salinity (Pearson et al. 2005). In the previous studies, entrainment rates in Desdemona Shoals were more variable than in any of the other reaches. Pearson et al. (2005) concluded that ?the dynamics behind the variable entrainment rates at Desdemona Shoals are not fully understood,? as well as finding that juvenile crab entrainment was not significantly correlated with salinity as it was for older crab. The present study was undertaken to address the question of whether the

  3. 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...

  4. 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.

  5. Positive abundance and negative distribution effects of a gastropod on an intertidal hermit crab.

    Science.gov (United States)

    Raimondi, Peter T; Lively, Curtis M

    1986-05-01

    Field experiments were used to determine the effect of a common intertidal snail (Nerita funiculata) on the use of space for foraging by the hermit crab Clibanarius digueti. Removals of Nerita resulted in an increased density of foraging Clibanarius, while additions of the gastropod had the opposite effect. The observed negative effect of the gastropod on individual hermit crabs appears to be food-related. Field surveys, however, suggested that the hermit crab population is limited by shell number, rather than food. Because Nerita contributes to the shell resource, its effect on the hermit crab population is positive. Nerita, therefore, has a negative effect on the distribution of foraging hermit crabs, but a positive effect on their abundance. Such decouplings of distribution and abundance effects are rare.

  6. 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.

  7. OBSERVATION AND SPECTRAL MEASUREMENTS OF THE CRAB NEBULA WITH MILAGRO

    Energy Technology Data Exchange (ETDEWEB)

    Abdo, A. A. [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Allen, B. T.; Chen, C. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Atkins, R. [Department of Physics, University of Wisconsin, 1150 University Ave, Madison, WI 53706 (United States); Aune, T.; Benbow, W.; Coyne, D. G.; Dorfan, D. E. [Santa Cruz Institute for Particle Physics, University of California, Santa Cruz, CA 95064 (United States); Berley, D.; Blaufuss, E.; Bussons, J. [Department of Physics, University of Maryland, College Park, MD 20742 (United States); Bonamente, E.; Galbraith-Frew, J. [Department of Physics, Michigan Technological University, Houghton, MI 49931 (United States); Christopher, G. E.; Fleysher, L.; Fleysher, R. [Department of Physics, New York University, New York, NY 10003 (United States); DeYoung, T.; Falcone, A. [Department of Physics, Pennsylvania State University, University Park, PA 16802 (United States); Dingus, B. L. [Group P-23, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Ellsworth, R. W. [School of Physics, Astronomy and Computational Sciences, George Mason University, Fairfax, VA 22030 (United States); and others

    2012-05-01

    The Crab Nebula was detected with the Milagro experiment at a statistical significance of 17 standard deviations over the lifetime of the experiment. The experiment was sensitive to approximately 100 GeV-100 TeV gamma-ray air showers by observing the particle footprint reaching the ground. The fraction of detectors recording signals from photons at the ground is a suitable proxy for the energy of the primary particle and has been used to measure the photon energy spectrum of the Crab Nebula between {approx}1 and {approx}100 TeV. The TeV emission is believed to be caused by inverse-Compton upscattering of ambient photons by an energetic electron population. The location of a TeV steepening or cutoff in the energy spectrum reveals important details about the underlying electron population. We describe the experiment and the technique for distinguishing gamma-ray events from the much more-abundant hadronic events. We describe the calculation of the significance of the excess from the Crab and how the energy spectrum is fitted. The differential photon energy spectrum, including the statistical errors from the fit, obtained using a simple power-law hypothesis for data between 2005 September and 2008 March is (6.5 {+-} 0.4) Multiplication-Sign 10{sup -14}(E/10 TeV){sup -3.1{+-}0.1}(cm{sup 2} s TeV ){sup -1} between {approx}1 TeV and {approx}100 TeV. Allowing for a possible exponential cutoff, the photon energy spectrum is fitted as (2.5{sup +0.7}{sub -0.4}) Multiplication-Sign 10{sup -12}(E/3 TeV){sup -2.5{+-}0.4}exp (- E/32{sup +39}{sub -18} TeV) (cm{sup 2} s TeV){sup -1}. The results are subject to an {approx}30% systematic uncertainty in the overall flux and an {approx}0.1 systematic uncertainty in the power-law indices quoted. Uncertainty in the overall energy scale has been absorbed into these errors. Fixing the spectral index to values that have been measured below 1 TeV by IACT experiments (2.4-2.6), the fit to the Milagro data suggests that Crab exhibits a

  8. Machine Protection Studies for a Crab Cavity in the LHC

    CERN Document Server

    Yee-Rendon, B; Baer, T; Barranco, J; Calaga, R; Marsili, A; Tomas, R; Zimmermann, F

    2013-01-01

    Crab cavities (CCs) apply a transverse kick that rotates the bunches so as to have a head-on collision at the interaction point (IP). Such cavities were successfully used to improve the luminosity of KEKB. They are also a key ingredient of the HL-LHC project to increase the luminosity of the LHC. As CCs can rapidly change the particle trajectories, machine protection studies are required to assess the beam losses due to fast CC failures. In this paper, we discuss the effect of rapid voltage or phase changes in a CC for the HL-LHC layout using measured beam distributions from the present LHC.

  9. Taxonomy Icon Data: crab-eating macaque [Taxonomy Icon

    Lifescience Database Archive (English)

    Full Text Available crab-eating macaque Macaca fascicularis Chordata/Vertebrata/Mammalia/Theria/Eutheria/Primate Macaca_fasci...cularis_L.png Macaca_fascicularis_NL.png Macaca_fascicularis_S.png Macaca_fascicularis..._NS.png http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Macaca+fascicularis&t=L http://biosciencedbc.jp/tax...onomy_icon/icon.cgi?i=Macaca+fascicularis&t=NL http://biosciencedbc.jp/taxonomy_i...con/icon.cgi?i=Macaca+fascicularis&t=S http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Macaca+fascicularis&t=NS ...

  10. 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.

  11. DNA barcoding detected improper labelling and supersession of crab food served by restaurants in India.

    Science.gov (United States)

    Vartak, Vivek Rohidas; Narasimmalu, Rajendran; Annam, Pavan Kumar; Singh, Dhirendra P; Lakra, Wazir S

    2015-01-01

    Detection of improper labelling of raw and processed seafood is of global importance for reducing commercial fraud and enhancing food safety. Crabs are crustaceans with intricate morphological as well as genetic divergence among species and are popular as seafood in restaurants. Owing to the high number of crab species available, it can be difficult to identify those included in particular food dishes, thus increasing the chance of supersession. DNA barcoding is an advanced technology for detecting improper food labelling and has been used successfully to authenticate seafood. This study identified 11 edible crab species from India by classical taxonomy and developed molecular barcodes with the cytochrome c oxidase I (COI) gene. These barcodes were used as reference barcodes for detecting any improper labelling of 50 restaurant crab samples. Neighbour-joining tree analysis with COI barcodes showed distinct clusters of restaurant samples with respective reference species. The study demonstrated 100% improper labelling of restaurant samples to cover up acts of inferior crab supersession. DNA barcoding successfully identified 11 edible crabs in accordance with classical taxonomy and discerned improper crab food labelling in restaurants of India. © 2014 Society of Chemical Industry.

  12. Parasites of the shore crab Carcinus maenas (L.): implications for reproductive potential and invasion success.

    Science.gov (United States)

    Zetlmeisl, C; Hermann, J; Petney, T; Glenner, H; Griffiths, C; Taraschewski, H

    2011-03-01

    The European shore crab, Carcinus maenas, is one of the most successful marine invasive species. Its success has been in part attributed to the loss of parasites, rekindling an interest in host-parasite interactions and impacts on host fitness in this crab. In the present study, we investigated C. maenas populations from Europe, South Africa and Australia for parasites, and assessed their impact on the fitness of male crabs. For the shore crab, testes weight along with success in mating competition is traded off against other life-history traits. We therefore used this parameter as an indicator both for reproductive fitness and a possible resource trade-off in response to parasite infestation. In the native range, crabs infested with Sacculina carcini showed significantly lower testes weight than uninfected crabs. However, helminth parasites did not generally cause reduced testes weights. Crab populations from South Africa and Australia were either parasitized at very low prevalences, or were completely parasite free. However, no population level effect of this parasite release was reflected in testes weight. These findings do not support a severe fitness impact of helminth parasites on C. maenas, which questions the role of parasites on its population dynamics, both in the native area and for invasive success.

  13. 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.

  14. 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.

  15. Infection Status of Freshwater Crabs and Crayfish with Metacercariae of Paragonimus westermani in Korea

    Science.gov (United States)

    Kim, Eun-Min; Kim, Jae-Lip; Choi, Sung-Il; Lee, Soon-Hyung

    2009-01-01

    The present study investigated the infection status of Paragonimus westermani metacercariae in freshwater crabs (n = 363) and crayfish (n = 31) from October 2007 to October 2008 using the crush method. All of the freshwater crabs, Eriocheir japonicus, were negative for P. westermani metacercariae while 10 (32.3%) of the 31 examined crayfish were positive. The 10 positive crayfish were caught in Haenam, Jeollanam-do, and there were 8-59 (mean 28.4) metacrcariae per infected crayfish. These results suggest that P. westermani metacerariae are still transmitted by crayfish enzootically in southern Korea, and that freshwater crabs may transmit metacercariae only on rare occasions. PMID:19967096

  16. 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

  17. 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

    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...

  18. No barrier to emergence of bathyal king crabs on the Antarctic shelf

    DEFF Research Database (Denmark)

    Aronson, Richard B.; Smith, Kathryn E.; Vos, Stephanie C.

    2015-01-01

    showed that abundant, predatory king crabs comprise a reproductively viable population at 841- to 2,266-m depth. Depth profiles of temperature, salinity, habitat structure, food availability, and predators indicate that there are no barriers to prevent king crabs from moving upward onto the outer shelf...... at 400–550 m. A cold-water barrier above 200 m could be breached within the next few decades. Emergence of king crabs on the shelf could have catastrophic consequences for the unique seafloor communities of Antarctica....

  19. Detection of Paragonimus mexicanus (Trematoda) metacercariae in crabs from Oaxaca, Mexico.

    Science.gov (United States)

    Vargas-Arzola, Jaime; Segura-Salvador, Aristeo; Reyes-Velasco, Leobardo; Díaz-Chiguer, Dylan L; Márquez-Navarro, Adrián; León-Avila, Gloria; Ibañez-Cervantes, Gabriela; Camacho, Alejandro D; Sánchez-Manzano, Rosa Ma; Nogueda-Torres, Benjamín

    2014-09-01

    Metacercariae of Paragonimus mexicanus were collected in crabs Tehuana guerreroensis (Rathbun, 1933) in the municipality of Putla, Oaxaca, Mexico. Metacercariae were found in 20.8% of the crabs collected, with an average of 1.9 metacercarie per crab. Stained metacercariae showed the specific characteristics of P. mexicanus by morphology and sequencing a fragment of the 28S ribosomal gene obtained by PCR. These findings reveal that T. guerreroensis is an intermediate host for P. mexicanus; this new report is relevant considering the potential risk of transmission in the states of Oaxaca and Guerrero, Mexico. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. 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.

  1. Mate locating and access behaviour of the parasitic pea crab, Nepinnotheres novaezelandiae, an important parasite of the mussel Perna canaliculus

    Directory of Open Access Journals (Sweden)

    Trottier Oliver

    2015-01-01

    Full Text Available Pea crabs are globally ubiquitous symbionts in the marine environment that cause serious economic impact in the aquaculture production of several major bivalve species. However, little is known about their host-parasite interactions, especially the mating behaviour of these parasites that could prove useful for controlling their infestation in aquaculture. In this study, the mate location behaviour of male New Zealand pea crabs, Nepinnotheres novaezelandiae (Filhol, 1885, was observed when dwelling in its preferred host, the commercially important green-lipped mussel, Perna canaliculus. Given the cryptic behaviour of the male crabs, a novel trapping system was developed to determine whether male crabs would exit their mussel hosts in response to an upstream female crab. The presence of receptive female crabs placed upstream successfully attracted 60% of male crabs from their host over 24 h. Observations of the nocturnal mate-finding behaviour of male crabs were made in darkness using infrared video recordings. Males spent on average 49 min on empty hosts and never left a mussel containing a female conspecific once found, spending 200 min on average to gain entry to the mussel. Male crabs were often observed stroking the mantle edge of the mussel whilst attempting to gain entry, successfully increasing mussel valve gape during entry from 3.7 to 5.5 mm. A pheromone-based mate location system is likely used by this crab to greatly reduce the risks associated with the location of females.

  2. Blood collection from the American horseshoe crab, Limulus polyphemus.

    Science.gov (United States)

    Armstrong, Peter; Conrad, Mara

    2008-10-13

    The horseshoe crab has the best-characterized immune system of any long-lived invertebrate. The study of immunity in horseshoe crabs has been facilitated by the ease in collecting large volumes of blood and from the simplicity of the blood. Horseshoe crabs show only a single cell type in the general circulation, the granular amebocyte. The plasma has the salt content of sea water and only three abundant proteins, hemocyanin, the respiratory protein, the C-reactive proteins, which function in the cytolytic destruction of foreign cells, including bacterial cells, and alpha2-macroglobulin, which inhibits the proteases of invading pathogens. Blood is collected by direct cardiac puncture under conditions that minimize contamination by lipopolysaccharide (a.k.a., endotoxin, LPS), a product of the Gram-negative bacteria. A large animal can yield 200 - 400 mL of blood. For the study of the plasma, blood cells are immediately removed from the plasma by centrifugation and the plasma can then be fractionated into its constituent proteins. The blood cells are conveniently studied microscopically by collecting small volumes of blood into LPS-free isotonic saline (0.5 M NaCl) under conditions that permit direct microscopic examination by placing one of more LPS-free coverglasses on the culture dish surface, then mounting those coverglasses in simple observation chambers following cell attachment. A second preparation for direct observation is to collect 3 - 5 mL of blood in a LPS-free embryo dish and then explanting fragments of aggregated amebocytes to a chamber that sandwiches the tissue between a slide and a coverglass. In this preparation, the motile amebocytes migrate onto the coverglass surface, where they can readily be observed. The blood clotting system involves aggregation of amebocytes and the formation of an extracellular clot of a protein, coagulin, which is released from the secretory granules of the blood cells. Biochemical analysis of washed blood cells requires

  3. 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.

  4. 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...

  5. 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...

  6. 50 CFR Table 2b to Part 679 - Species Codes: FMP Prohibited Species and CR Crab

    Science.gov (United States)

    2010-10-01

    ... ✓ Dungeness Cancer magister 910 ✓ King, blue Paralithodes platypus 922 ✓ ✓ King, golden (brown) Lithodes... opilio 932 ✓ ✓ Tanner, triangle Chionoecetes angulatus 934 ✓ Verrilli crab Paralomis verrilli 953...

  7. [Changes of historical Paragonimus metacercaria infection rates of freshwater crabs in Yongjia County].

    Science.gov (United States)

    Zhou, Teng-Jian; Chen, Hai-Qiang; Hong, Jia-Lin

    2013-12-01

    To understand the changes of Paragonimus metacercaria infection rates of freshwater crabs in Paragonimus endemic areas and explore the causes in Yongjia County, Zhejiang Province, China. A field investigation was carried out. The freshwater crabs were collected and the metacercaria were separated from the crabs. The infection rates, infectiosities and infection indexes were calculated and the results were vertically compared with the historical findings. The causes of the changes were discussed. Compared with those in 1980, the average infection rate in original endemic areas decreased from 59.71% to 21.50% (P Paragonimus metacercaria infection rate in crabs is lower than before in Yongjia County, but some super high epidemic focus of paragonimiasis still exists. Therefore, we still should strengthen the control measures.

  8. 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

  9. 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,...

  10. 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.

  11. A case for the commons: The Snow Crab in the Barents

    DEFF Research Database (Denmark)

    Kaiser, Brooks; Kourantidou, Melina; Fernandez, Linda

    2018-01-01

    , article 77, part VI)). This shifts the regulatory environment for the crab in ways that exacerbate the invasion in exchange for protection of local gains. Such problems will increase in magnitude and impact as climate changes increasingly affect species' ranges. Optimal decision-making regarding...... challenges that are increasing under climate change. These include transboundary resource management and tradeoffs between local economic returns and Total Economic Value. The case of the valuable, yet invasive, crab species, Chionoecetes Opilio (Snow Crab) in the Barents Sea illustrates the concerns....... The spread of the crab has known and unknown ecosystem and commercial fishery risks, particularly to uncertain ecosystem values. We show how the progression of the biological invasion interacts with human strategic behavior to identify limitations of management options. Open access harvesting of the species...

  12. Impact of CRAB symptoms in survival of patients with symptomatic myeloma in novel agent era

    Directory of Open Access Journals (Sweden)

    Aya Nakaya

    2017-02-01

    Full Text Available The acronym CRAB summarizes the most typical clinical manifestations of multiple myeloma, these being hypercalcemia, renal failure, anemia, and bone disease. CRAB can be used to distinguish between active, symptomatic multiple myeloma and monoclonal gammopathy of undermined significance or smoldering myeloma. The distinction is relevant not only for classification and diagnosis but also for therapy. CRAB factors influence the prognosis of multiple myeloma. However, it is unclear whether the presence of CRAB factors has an influence on the prognosis of myeloma treated with novel agents. In the current study, patients with hypercalcemia and bone disease showed a significantly worse prognosis, whereas anemia and renal failure showed no difference in survival. Novel agents used for treatment of patients with renal failure suggested a favorable outcome compared with conventional therapy. Bone disease was the most common factor and may have the strongest prognostic value in symptomatic myeloma patients using novel agents.

  13. 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.

  14. 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...

  15. 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...

  16. 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...

  17. 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.

  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. AFSC/RACE/GAP/Nichol: Archival tag depth and temperature data from red king crab

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In December of 2009, a total of 135 adult male red king crab (Paralithodes camtschaticus) were tagged with depth and temperature recording archival tags and released...

  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. 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...

  3. 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

  4. 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 ...

  5. 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.

  6. Potential causes of mortality for horseshoe crabs (Limulus polyphemus) during the biomedical bleeding process

    OpenAIRE

    Hurton, L.; Berkson, J.

    2006-01-01

    Biomedical companies catch and bleed horseshoe crabs for the production of Limulus amebocyte lysate (LAL), a product used for protecting public health (Berkson and Shuster, 1999). LAL is a clotting agent, derived solely from horseshoe crab blood cells, which is used to detect the presence of pathogenic gramnegative bacteria in injectable drugs and implantable medical and dental devices (Mikkelsen, 1988; Novitsky, 1991). In addition, LAL is used in many diagnostic tests for such illnesses as g...

  7. Potential causes of mortality for horseshoe crabs (Limulus polyphemus) during the biomedical bleeding process

    OpenAIRE

    Hurton, Lenka; Berkson, Jim

    2006-01-01

    Biomedical companies catch and bleed horseshoe crabs for the production of Limulus amebocyte lysate (LAL), a product used for protecting public health (Berkson and Shuster, 1999). LAL is a clotting agent, derived solely from horseshoe crab blood cells, which is used to detect the presence of pathogenic gramnegative bacteria in injectable drugs and implantable medical and dental devices (Mikkelsen, 1988; Novitsky, 1991). In addition, LAL is used in many diagnostic tests for such illnesses a...

  8. 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.

  9. Seed Predation by the Shore Crab Carcinus maenas: A Positive Feedback Preventing Eelgrass Recovery?

    Science.gov (United States)

    2016-01-01

    There is an increasing interest to restore the ecosystem services that eelgrass provides, after their continuous worldwide decline. Most attempts to restore eelgrass using seeds are challenged by very high seed losses and the reasons for these losses are not all clear. We assess the impact of predation on seed loss and eelgrass establishment, and explore methods to decrease seed loss during restoration in the Swedish northwest coast. In a laboratory study we identified three previously undescribed seed predators, the shore crab Carcinus maenas, the hermit crab Pagurus bernhardus and the sea urchin Strongylocentrotus droebachiensis, of which shore crabs consumed 2–7 times more seeds than the other two species. The importance of shore crabs as seed predators was supported in field cage experiments where one enclosed crab caused 73% loss of seeds over a 1-week period on average (~ 21 seeds per day). Seedling establishment was significantly higher (14%) in cages that excluded predators over an 8-month period than in uncaged plots and cages that allowed predators but prevented seed-transport (0.5%), suggesting that seed predation constitutes a major source of seed loss in the study area. Burying the seeds 2 cm below the sediment surface prevented seed predation in the laboratory and decreased predation in the field, constituting a way to decrease seed loss during restoration. Shore crabs may act as a key feedback mechanism that prevent the return of eelgrass both by direct consumption of eelgrass seeds and as a predator of algal mesograzers, allowing algal mats to overgrow eelgrass beds. This shore crab feedback mechanism could become self-generating by promoting the growth of its own nursery habitat (algal mats) and by decreasing the nursery habitat (seagrass meadow) of its dominant predator (cod). This double feedback-loop is supported by a strong increase of shore crab abundance in the last decades and may partly explain the regime shift in vegetation observed

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

    Directory of Open Access Journals (Sweden)

    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

  11. 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.

  12. 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.

  13. 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)

  14. 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].

  15. The importance of color in mate choice of the blue crab Callinectes sapidus.

    Science.gov (United States)

    Baldwin, Jamie; Johnsen, Sönke

    2009-11-01

    Visual displays often play a large role in animal communication, particularly in sexual interactions. The blue crab Callinectes sapidus is both colorful and highly visually responsive, yet almost all studies of their courtship have focused on chemical cues. In the blue crab's underwater environment, however, visual cues may function more rapidly and over a longer distance than chemical cues. Given that blue crabs are aggressive and cannibalistic, visual cues may therefore allow blue crabs to quickly evaluate potential mates from safer distances. In the present study we show that courtship and mate choice behavior in C. sapidus can be stimulated by visual cues alone. Further, we show that males have a preference for females with red claw dactyls. In binary choice experiments, males displayed more often to photographs of females with red claws than to those with white claws or to those with black claws that were isoluminant to the red ones. This strongly suggests that male blue crabs made their choices based on the hue of the red claws, further suggesting that blue crabs are capable of color vision and use color in mate choice.

  16. 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.

  17. Absolute quantification method and validation of airborne snow crab allergen tropomyosin using tandem mass spectrometry.

    Science.gov (United States)

    Abdel Rahman, Anas M; Lopata, Andreas L; Randell, Edward W; Helleur, Robert J

    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 μg m(-3) and 1.70-2.31 μg m(-3) for butchering and cooking stations, respectively. Crown Copyright © 2010. Published by Elsevier B.V. All rights reserved.

  18. Release from parasites as natural enemies: increased performance of a globally introduced marine crab

    Science.gov (United States)

    Torchin, Mark E.; Lafferty, Kevin D.; Kuris, Armand M.

    2001-01-01

    Introduced species often seem to perform better than conspecifics in their native range. This is apparent in the high densities they may achieve or the larger individual sizes they attain. A prominent hypothesis explaining the success of introduced terrestrial species is that they are typically free of or are less affected by the natural enemies (competitors, predators, and parasites) they encounter in their introduced range compared to their native range. To test this hypothesis in a marine system, we conducted a global assessment of the effect of parasitism and predation on the ecological performance of European green crab populations. In Europe, where the green crab is native, crab body size and biomass were negatively associated with the prevalence of parasitic castrators. When we compared native crab populations with those from introduced regions, limb loss (an estimator of predation) was not significantly lower in introduced regions, parasites infected introduced populations substantially less and crabs in introduced regions were larger and exhibited a greater biomass. Our results are consistent with the general prediction that introduced species suffer less from parasites compared to populations where they are native. This may partly explain why the green crab is such a successful invader and, subsequently, why it is a pest in so many places.

  19. Multispecies modeling for adaptive management of horseshoe crabs and red knots in the Delaware Bay

    Science.gov (United States)

    McGowan, Conor P.; Smith, David; Sweka, John A.; Martin, Julien; Nichols, James D.; Wong, Richard; Lyons, James E.; Niles, Lawrence J.; Kalasz, Kevin; Brust, Jeffrey; Klopfer, Michelle; Spear, Braddock

    2011-01-01

    Adaptive management requires that predictive models be explicit and transparent to improve decisions by comparing management actions, directing further research and monitoring, and facilitating learning. The rufa subspecies of red knots (Calidris canutus rufa), which has recently exhibited steep population declines, relies on horseshoe crab (Limulus polyphemus) eggs as their primary food source during stopover in Delaware Bay during spring migration. We present a model with two different parameterizations for use in the adaptive management of horseshoe crab harvests in the Delaware Bay that links red knot mass gain, annual survival, and fecundity to horseshoe crab dynamics. The models reflect prevailing hypotheses regarding ecological links between these two species. When reported crab harvest from 1998 to 2008 was applied, projections corresponded to the observed red knot population abundances depending on strengths of the demographic relationship between these species. We compared different simulated horseshoe crab harvest strategies to evaluate whether, given this model, horseshoe crab harvest management can affect red knot conservation and found that restricting harvest can benefit red knot populations. Our model is the first to explicitly and quantitatively link these two species and will be used within an adaptive management framework to manage the Delaware Bay system and learn more about the specific nature of the linkage between the two species.

  20. 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.

  1. The Influence of Diet Composition on Fitness of the Blue Crab, Callinectes sapidus.

    Science.gov (United States)

    Belgrad, Benjamin A; Griffen, Blaine D

    2016-01-01

    The physiological condition and fecundity of an organism is frequently controlled by diet. As changes in environmental conditions often cause organisms to alter their foraging behavior, a comprehensive understanding of how diet influences the fitness of an individual is central to predicting the effect of environmental change on population dynamics. We experimentally manipulated the diet of the economically and ecologically important blue crab, Callinectes sapidus, to approximate the effects of a dietary shift from primarily animal to plant tissue, a phenomenon commonly documented in crabs. Crabs whose diet consisted exclusively of animal tissue had markedly lower mortality and consumed substantially more food than crabs whose diet consisted exclusively of seaweed. The quantity of food consumed had a significant positive influence on reproductive effort and long-term energy stores. Additionally, seaweed diets produced a three-fold decrease in hepatopancreas lipid content and a simultaneous two-fold increase in crab aggression when compared to an animal diet. Our results reveal that the consumption of animal tissue substantially enhanced C. sapidus fitness, and suggest that a dietary shift to plant tissue may reduce crab population growth by decreasing fecundity as well as increasing mortality. This study has implications for C. sapidus fisheries.

  2. The Influence of Diet Composition on Fitness of the Blue Crab, Callinectes sapidus.

    Directory of Open Access Journals (Sweden)

    Benjamin A Belgrad

    Full Text Available The physiological condition and fecundity of an organism is frequently controlled by diet. As changes in environmental conditions often cause organisms to alter their foraging behavior, a comprehensive understanding of how diet influences the fitness of an individual is central to predicting the effect of environmental change on population dynamics. We experimentally manipulated the diet of the economically and ecologically important blue crab, Callinectes sapidus, to approximate the effects of a dietary shift from primarily animal to plant tissue, a phenomenon commonly documented in crabs. Crabs whose diet consisted exclusively of animal tissue had markedly lower mortality and consumed substantially more food than crabs whose diet consisted exclusively of seaweed. The quantity of food consumed had a significant positive influence on reproductive effort and long-term energy stores. Additionally, seaweed diets produced a three-fold decrease in hepatopancreas lipid content and a simultaneous two-fold increase in crab aggression when compared to an animal diet. Our results reveal that the consumption of animal tissue substantially enhanced C. sapidus fitness, and suggest that a dietary shift to plant tissue may reduce crab population growth by decreasing fecundity as well as increasing mortality. This study has implications for C. sapidus fisheries.

  3. Evolutionary morphology of the hemolymph vascular system in hermit and king crabs (Crustacea: Decapoda: Anomala).

    Science.gov (United States)

    Keiler, Jonas; Richter, Stefan; Wirkner, Christian S

    2013-07-01

    The morphological transformation of hermit crabs into crab-like king crabs in the evolution of decapod crustaceans represents a remarkable case of carcinization or evolutionary shaping into a crab-like form. In this study, we focus on internal organs such as the hemolymph vascular system and adjacent anatomical structures of several Recent hermit crab (Paguridae) and king crab (Lithodidae) species. There are various correspondences in the morphology of the arterial systems in the dorsal cephalothorax of the two taxa, especially with regard to the anterior aorta, anterior lateral arteries, and hepatic arteries. In the pleon, the posterior aorta in both taxa displays a proximal bifurcation and follows an asymmetrical course. The ventral vessel system, on the other hand, which mainly supplies the limbs, differs significantly between the taxa, with pagurids displaying the plesiomorphic condition. The pattern of the ventral vessel system in Lithodidae is influenced by morphological transformations of integumental structures during carcinization. One of these transformations was the broadening of the sternites, which resulted in a widening of the space between the endosternites. In addition, changes in the morphology of the endophragmal skeleton in Lithodidae led to an increase in the potential for intraspecific variability and interspecific variation in the arterial branching pattern. Copyright © 2013 Wiley Periodicals, Inc.

  4. 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

  5. Trading green backs for green crabs: evaluating the commercial shellfish harvest at risk from European green crab invasion.

    Science.gov (United States)

    Mach, Megan E; Chan, Kai Ma

    2013-01-01

    Nonnative species pose a threat to native biodiversity and can have immense impacts on biological communities, altering the function of ecosystems. How much value is at risk from high-impact invasive species, and which parameters determine variation in that value, constitutes critical knowledge for directing both management and research, but it is rarely available. We evaluated the value of the commercial shellfish harvest that is at risk in nearshore ecosystems of Puget Sound, Washington State, USA, from the invasive European green crab, Carcinus maenas . We assessed this value using a simple static ecological model combined with an economic model using data from Puget Sound's shellfish harvest and revenue and the relationship between C. maenas abundance and the consumption rate of shellfish. The model incorporates a range in C. maenas diet preference, calories consumed per year, and crab densities. C. maenas is likely to prey on commercially harvested hardshell clams, oysters, and mussels, which would likely reduce additional revenue from processing and distribution, and the number of jobs associated with these fisheries. The model results suggest possible revenue losses of these shellfish ranging from $1.03-23.8 million USD year -1 (2.8-64% losses), with additional processing and distribution losses up to $17.6 million USD and 442 job positions each year associated with a range of plausible parameter values. The broad range of values reflects the uncertainty in key factors underlying impacts, factors that are highly variable across invaded regions and so not knowable a priori . However, future research evaluating species invasions can reduce the uncertainty of impacts by characterizing several key parameters: density of individuals, number of arrivals, predation and competition interactions, and economic impacts. This study therefore provides direction for research to inform more accurate estimates of value-at-risk, and suggests substantial motivation for

  6. Infestation of parasitic rhizocephalan barnaclesSacculina beauforti(Cirripedia, Rhizocephala) in edible mud crab,Scylla olivacea.

    Science.gov (United States)

    Waiho, Khor; Fazhan, Hanafiah; Glenner, Henrik; Ikhwanuddin, Mhd

    2017-01-01

    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.

  7. 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

    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......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...

  8. 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.

  9. 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

  10. 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...

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. Can crabs kill like a keystone predator? A field-test of the effects of crab predation on mussel mortality on a northeast Pacific rocky shore.

    Directory of Open Access Journals (Sweden)

    Wesley W Hull

    Full Text Available Predation can strongly influence community structure and ecosystem function, so the loss of key predators can have dramatic ecological consequences, unless other predatory species in the system are capable of playing similar ecological roles. In light of the recent outbreak of sea star wasting disease (SSWD and subsequent depletion of west coast sea star populations, including those of the keystone predator Pisaster ochraceus, we examined whether large mobile crabs could play a role as predators on mussels (Mytilus californianus on a rocky shore in Northern California. Using a combination of sea star removal and predator exclusion cages we found that mussel mortality was 43-294 times greater in uncaged treatments versus caged treatments. Mortality on uncaged mussels at low tidal elevations was due to predation by large mobile crabs (Cancer productus and Romaleon antennarium; confirmed by the presence of mussel shell fragments and documented attacks on wax snail replicas. Laboratory feeding assays indicated that crabs, on a per unit biomass basis, can consume almost twenty-five times as many mussels per day than sea stars, which together with the results of our field experiment, suggest that large predatory crabs could play an important role in maintaining ecosystem function through their predation on mussels on rocky shores where P. ochraceus are rare, absent, or have been depleted by SSWD.

  16. 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.

  17. 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.

  18. CRAB NEBULA: FIVE-YEAR OBSERVATION WITH ARGO-YBJ

    Energy Technology Data Exchange (ETDEWEB)

    Bartoli, B.; Catalanotti, S.; D' Ettorre Piazzoli, B.; Di Girolamo, T. [Dipartimento di Fisica dell' Università di Napoli " Federico II," Complesso Universitario di Monte Sant' Angelo, via Cinthia, I-80126 Napoli (Italy); Bernardini, P.; D' Amone, A.; De Mitri, I. [Dipartimento Matematica e Fisica " Ennio De Giorgi," Università del Salento, via per Arnesano, I-73100 Lecce (Italy); Bi, X. J.; Cao, Z.; Chen, S. Z. [Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, P.O. Box 918, 100049 Beijing (China); Branchini, P.; Budano, A. [Istituto Nazionale di Fisica Nucleare, Sezione di Roma Tre, via della Vasca Navale 84, I-00146 Roma (Italy); Camarri, P. [Dipartimento di Fisica dell' Università di Roma " Tor Vergata," via della Ricerca Scientifica 1, I-00133 Roma (Italy); Cardarelli, R.; Di Sciascio, G. [Istituto Nazionale di Fisica Nucleare, Sezione di Roma Tor Vergata, via della Ricerca Scientifica 1, I-00133 Roma (Italy); Chen, T. L.; Danzengluobu [Tibet University, 850000 Lhasa, Xizang (China); Creti, P. [Istituto Nazionale di Fisica Nucleare, Sezione di Lecce, via per Arnesano, I-73100 Lecce (Italy); Cui, S. W. [Hebei Normal University, Shijiazhuang 050016 Hebei (China); Dai, B. Z., E-mail: vernetto@to.infn.it [Yunnan University, 2 North Cuihu Rd., 650091 Kunming, Yunnan (China); Collaboration: ARGO-YBJ Collaboration; and others

    2015-01-10

    The ARGO-YBJ air shower detector monitored the Crab Nebula gamma-ray emission from 2007 November to 2013 February. The integrated signal, consisting of ∼3.3 × 10{sup 5} events, reached the statistical significance of 21.1 standard deviations. The obtained energy spectrum in the energy range 0.3-20 TeV can be described by a power law function dN/dE = I {sub 0} (E/2 TeV){sup –α}, with a flux normalization I {sub 0} = (5.2 ± 0.2) × 10{sup –12} photons cm{sup –2} s{sup –1} TeV{sup –1} and α = 2.63 ± 0.05, corresponding to an integrated flux above 1 TeV of 1.97 × 10{sup –11} photons cm{sup –2} s{sup –1}. The systematic error is estimated to be less than 30% for the flux normalization and 0.06 for the spectral index. Assuming a power law spectrum with an exponential cutoff dN/dE = I {sub 0} (E/2 TeV){sup –α} exp (–E/E {sub cut}), the lower limit of the cutoff energy E {sub cut} is 12 TeV, at 90% confidence level. Our extended data set allows the study of the TeV emission over long timescales. Over five years, the light curve of the Crab Nebula in 200-day bins is compatible with a steady emission with a probability of 7.3 × 10{sup –2}. A correlated analysis with Fermi-LAT data over ∼4.5 yr using the light curves of the two experiments gives a Pearson correlation coefficient r = 0.56 ± 0.22. Concerning flux variations on timescales of days, a ''blind'' search for flares with a duration of 1-15 days gives no excess with a significance higher than four standard deviations. The average rate measured by ARGO-YBJ during the three most powerful flares detected by Fermi-LAT is 205 ± 91 photons day{sup –1}, consistent with the average value of 137 ± 10 day{sup –1}.

  19. 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

  20. Size-frequency distribution, growth, and mortality of snow crab (Chionoecetes opilio) and arctic lyre crab (Hyas coarctatus) in the chukchi sea from 2009 to 2013

    Science.gov (United States)

    Groß, Jasmin; Konar, Brenda; Brey, Thomas; Grebmeier, Jacqueline M.

    2017-10-01

    The snow crab Chionoecetes opilio and Arctic lyre crab Hyas coarctatus are prominent members of the Chukchi Sea epifaunal community. A better understanding of their life history will aid in determining their role in this ecosystem in light of the changing climate and resource development. In this study, the size frequency distribution, growth, and mortality of these two crab species was examined in 2009, 2010, 2012, and 2013 to determine temporal and spatial patterns within the eastern Chukchi Sea, and to identify potential environmental drivers of the observed patterns. Temporally, the mean size of both sexes of C. opilio and H. coarctatus decreased significantly from 2009 to 2013, with the number of rare maximum sized organisms decreasing significantly to near absence in the latter two study years. Spatially, the mean size of male and female crabs of both species showed a latitudinal trend, decreasing from south to north in the investigation area. Growth of both sexes of C. opilio and H. coarctatus was linear over the sampled size range, and mortality was highest in the latter two study years. Life history features of both species related to different environmental parameters in different years, ranging from temperature, the sediment carbon to nitrogen ratio of the organic content, and sediment grain size distribution. Likely explanations for the observed temporal and spatial variability are ontogenetic migrations of mature crabs to warmer areas possibly due to cooler water temperatures in the latter two study years, or interannual fluctuations, which have been reported for C. opilio populations in other areas where successful waves of recruitment were estimated to occur in eight year intervals. Further research is suggested to determine if the spatial and temporal patterns found in this study are part of the natural variability in this system or if they are an indication of long-term trends.

  1. Neutrino Analysis of the September 2010 Crab Nebula Flare and Time-integrated Constraints on Neutrino Emission From the Crab Using IceCube

    Science.gov (United States)

    Stamatikos, M.; Abbasi, R.; Abdou, Y.; Abu-Zayyad, T.; Adams, J.; Aguliar, J. A.; Ahlers, M.; Altmann, D.; Andeen, K.; Auffenberg, J.; hide

    2012-01-01

    We present the results for a search of high-energy muon neutrinos with the IceCube detector in coincidence with the Crab nebula flare reported on September 2010 by various experiments. Due to the unusual flaring state of the otherwise steady source we performed a prompt analysis of the 79-string configuration data to search for neutrinos that might be emitted along with the observed gamma-rays. We performed two different and complementary data selections of neutrino events in the time window of 10 days around the flare. One event selection is optimized for discovery of E(sub nu)(sup -2) neutrino spectrum typical of 1st order Fermi acceleration. A similar event selection has also been applied to the 40-string data to derive the time-integrated limits to the neutrino emission from the Crab [35]. The other event selection was optimized for discovery of neutrino spectra with softer spectral index and TeV energy cut-offs as observed for various galactic sources in gamma-rays. The 90% CL best upper limits on the Crab flux during the 10 day flare are 4.73 x 10(exp -11) per square centimeter per second TeV (sup -1) for an E(sub nu) (sup -2) neutrino spectrum and 2.50 x 10(exp -10) per square centimeter per second TeV(sup -1) for a softer neutrino spectra of E(sub nu)(sup -2.7), as indicated by Fermi measurements during the flare. IceCube has also set a time-integrated limit on the neutrino emission of the Crab using 375.5 days of livetime of the 40-string configuration data. This limit is compared to existing models of neutrino production from the Crab and its impact on astrophysical parameters is discussed. The most optimistic predictions of some models are already rejected by the IceCube neutrino telescope with more than 90% CL.

  2. 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

  3. Spatial distribution of the crab larvae (Decapoda: Anomura et Brachyura) in Possyet Bay (Peter the Great Bay of the Sea of Japan) in 2000-2001

    Science.gov (United States)

    Grigoryeva, N. I.

    2009-10-01

    The analysis of the data obtained during the plankton surveys in Possyet Bay (Peter the Great Bay of the Sea of Japan) in 2000-2001 is presented. The larvae of eight crab species were registered in the plankton: the red king crab Paralithodes camtschaticus (Tilesius, 1815), the snow (opilio) crab Chionoecetes opilio (Fabricius, 1780), the Arctic lyre crab Hyas coarctatus ursinus (Leach, 1815), the kelp crab Pugettia quadridens (de Haan, 1839), the helmet crab Telmessus cheiragonus (Tilesius, 1815), the Japanese swimming crab Charybdis japonica (A. Milne-Edwards, 1861), the pea crab Pinnixa rathbuni (Sakai, 1934), and the porcelain crab Pachycheles stevensii (Stimpson, 1858). These species belonged to six families: Lithodidae, Atelecyclidae, Majidae, Portunidae, Porcellanidae, and Pinnotheridae. The role of the variability of some of the hydrological factors in the meroplankton larvae development was studied. In May, the crab larvae were found mostly in the open part of the bay. In June, they were transported by the current to the northern part of the bay. In July, they spread uniformly in all the bay areas; however, patchiness was observed. The maximal population density of the crab larvae was registered for July and varied from 6.8 to 23.3 ind. m-3. The crab larvae appeared in the plankton in 2000 and 2001 earlier than for the average season.

  4. 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.

  5. Effects of horseshoe crab harvest in delaware bay on red knots: Are harvest restrictions working?

    Science.gov (United States)

    Niles, L.J.; Bart, J.; Sitters, H.P.; Dey, A.D.; Clark, K.E.; Atkinson, P.W.; Baker, Allan J.; Bennett, K.A.; Kalasz, K.S.; Clark, N.A.; Clark, J.; Gillings, S.; Gates, A.S.; Gonzalez, P.M.; Hernandez, D.E.; Minton, C.D.T.; Morrison, R.I.G.; Porter, R.R.; Ross, R.K.; Veitch, C.R.

    2009-01-01

    Each May, red knots (Calidris canutus rufa) congregate in Delaware Bay during their northward migration to feed on horseshoe crab eggs (Limulus polyphemus) and refuel for breeding in the Arctic. During the 1990s, the Delaware Bay harvest of horseshoe crabs for bait increased 10-fold, leading to a more than 90% decline in the availability of their eggs for knots. The proportion of knots achieving weights of more than 180 grams by 26-28 May, their main departure period, dropped from 0.6-0.8 to 0.14-0.4 over 1997-2007. During the same period, the red knot population stopping in Delaware Bay declined by more than 75%, in part because the annual survival rate of adult knots wintering in Tierra del Fuego declined. Despite restrictions, the 2007 horseshoe crab harvest was still greater than the 1990 harvest, and no recovery of knots was detectable. We propose an adaptive management strategy with recovery goals and annual monitoring that, if adopted, will both allow red knot and horseshoe crab populations to recover and permit a sustainable harvest of horseshoe crabs.

  6. 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.

  7. Secondary periodicities of microbursts of TeV gamma rays from the Crab pulsar

    International Nuclear Information System (INIS)

    Vishwanath, P.R.; Bhat, P.N.; Gupta, S.K.; Ramanamurthy, P.V.

    1985-01-01

    Observations were made during the past several years on the Crab pulsar using the Ooty atmospheric Cerenkov array with the aim of detecting possible emission of ultra high energy gamma rays by the pulsar. During the course of these observations, it was found that the Crab pulsar emits TeV gamma rays in bursts of short duration. The microbursts of TeV gamma rays from the Crab pulsar, which were seen in the data of at least three years, also reveal interesting secondary periodicities. It was noticed at first that some bursts could be connected with the others that occurred during the same night or during the next two nights with integral number of cycles of periods 43 + or - 1 minute. Ten possible periods in the vicinity of 43 minutes were determined for all the combinations of bursts for each year. The best values of periods thus obtained were different from year to year. But when, instead of the real time, the number of Crab cycles elapsed between the bursts was used as the unit of time, two values of burst periods - 77460 and 77770 Crab cycles - were found to be significant in the data of at least two years. A Monte Carlo simulation using 1500 trial periods chosen randomly within + or - 5 minutes of the original burst period did not reveal any value of the period as significant

  8. 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.

  9. 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.

  10. 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.

  11. Exploring the molecular basis of adaptive evolution in hydrothermal vent crab Austinograea alayseae by transcriptome analysis.

    Directory of Open Access Journals (Sweden)

    Min Hui

    Full Text Available Elucidating the genetic mechanisms of adaptation to the hydrothermal vent in organisms at genomic level is significant for understanding the adaptive evolution process in the extreme environment. We performed RNA-seq on four different tissues of a vent crab species, Austinograea alayseae, producing 725,461 unigenes and 134,489 annotated genes. Genes related to sensory, circadian rhythm, hormone, hypoxia stress, metal detoxification and immunity were identified. It was noted that in the degenerated eyestalk, transcription of phototransduction related genes which are important for retinal function was greatly reduced; three crucial neuropeptide hormones, one molt-inhibiting and two crustacean hyperglycemic hormone precursors were characterized with conserved domains; hypoxia-inducible factor 1 and two novel isoforms of metallothioneins in the vent crabs were discovered. An analysis of 6,932 orthologs among three crabs A. alayseae, Portunus trituberculutus and Eriocheir sinensis revealed 19 positive selected genes (PSGs. Most of the PSGs were involved in immune responses, such as crustins and anti-lipopolysaccharide factor, suggesting their function in the adaptation to environment. The characterization of the first vent crab transcriptome provides abundant resources for genetic and evolutionary studies of this species, and paves the way for further investigation of vent adaptation process in crabs.

  12. 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.

  13. Mud crab ecology encourages site-specific approaches to fishery management

    Science.gov (United States)

    Dumas, P.; Léopold, M.; Frotté, L.; Peignon, C.

    2012-01-01

    Little is known about the effects of mud crabs population patterns on their exploitation. We used complementary approaches (experimental, fisher-based) to investigate how small-scale variations in density, size and sex-ratio related to the ecology of S. serrata may impact fishing practices in New Caledonia. Crabs were measured/sexed across 9 stations in contrasted mangrove systems between 2007 and 2009. Stations were described and classified in different kinds of mangrove forests (coastal, riverine, and estuarine); vegetation cover was qualitatively described at station scale. Annual catch was used as an indicator of fishing pressure. Middle-scale environmental factors (oceanic influence, vegetation cover) had significant contributions to crab density (GLM, 84.8% of variance), crab size and sex-ratio (social implications in the Pacific area, where land tenure system and traditional access rights prevent most fishers from freely selecting their harvest zones. This offers a great opportunity to encourage site-specific management of mud crab fisheries.

  14. The Effects of the Deepwater Horizon Oil Spill on Blue Crab Embryos

    Science.gov (United States)

    Kelly, K.; Taylor, C.

    2016-02-01

    Blue crabs (Callinectes Sapidus) are ubiquitous along the east coast; however, they play a particularly integral role in the Gulf of Mexico (GOM), where, not only are they a keystone species, but they are also socioeconomically important. The survival of embryos is necessary to insure adequate recruitment into the next generation. Because the Deepwater Horizon oil spill occurred during the peak of the blue crab spawning season, the incident likely impacted blue crab embryos. This study was conducted in order to assess the effect of oil on embryonic growth and development. The eggs from seven different female crabs were collected from the GOM throughout the spawning season and exposed to an oil concentration of 500ppm (the approximate concentration of oil at the site of the DWH). We found that, while the overall mortality rate and the proportion hatched was not significantly different between embryos that were exposed to oil and those not exposed to oil, the proportion of prezoea in the experimental group was significantly greater. Prezoea are known to occur in suboptimal conditions such as low salinities, or bacterial and fungal infection, and have been documented to have reduced survival. Our results support these findings and indicate that oil concentrations of 500 ppm negatively impact the development of blue crab embryos. This study sheds light on a critical, but poorly investigated, phase of an important species' life cycle in addition to providing further insight into the effects of the DWH spill.

  15. Shell use by the hermit crab Calcinus californiensis at different levels of the intertidal zone

    Directory of Open Access Journals (Sweden)

    Elsah Arce

    2011-02-01

    Full Text Available The gastropod shell use of the hermit crab Calcinus californiensis was studied at Troncones, Guerrero, México. Hermit crabs were captured at two different levels of the intertidal zone, in wave-protected and wave-exposed sites. C. californiensis occupied shells of 18 gastropod species. At both wave-action sites, Cantharus sanguinolentus was the most occupied shell. Columbella sp. was used more by females than by males, and Nerita scabricosta was more used by males. The frequency of use of the shells was different between the different wave sites. N. scabricosta and Columbella sp. were occupied more at the wave-protected than at the exposed sites; C. sanguinolentus and Stramonita biserialis were occupied more at the exposed sites. The hermit crabs at the wave-exposed sites occupied heavier and thicker shells compared with the crabs from the protected sites. The Olmstead-Tukey diagram showed eight shell species as dominant in the wave-protected sites, and seven in the wave-exposed sites. Ten shell species were rare in the wave-protected sites, and six in the wave-exposed sites. The rare shells occupied by the hermit crabs were relatively heavier than the dominant shells in both site types. Our results suggest that the shell weight is important in sites that are greatly affected by the hydrodynamics.

  16. 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.

  17. Sampling technique affects the population structure assessments of fiddler crab Minuca vocator (Herbst, 1804 (Ocypodidae: Gelasiminae

    Directory of Open Access Journals (Sweden)

    Karine Delevati Colpo

    Full Text Available Abstract We examined how the sampling technique can affect the evaluation of Minuca vocator (Herbst, 1804 population structure. We used two sampling procedures: catch-per-unit-effort (CPUE and quadrat technique (QT. Body size, size-frequency distribution, population density, juvenile recruitment rates, proportion of ovigerous females and sex ratio were compared between the sampling procedures. QT allowed us to estimate and compare crab and burrow densities. CPUE sampled both adult crabs and the largest crabs more frequently, whereas QT recorded a greater proportion of smaller crabs. CPUE underestimated the size of M. vocator populations, while density estimates obtained with QT were accurate. The proportion of juveniles was higher with QT than with CPUE, suggesting that recruitment rates estimated by QT were more suitable. The sampling effort provided by CPUE was more efficient for obtaining ovigerous-dependent information than QT. Both sampling techniques showed a predominance of males in all three M. vocator populations. The population density estimation based on burrows overestimated the natural density of M. vocator in all mangroves. Our results suggest that neither CPUE nor QT individually were accurate sampling techniques, but together provided reliable assessments of fiddler crab populations.

  18. Temporal changes in brachyuran crab diversity along heterogeneous habitat in a mangrove ecosystem of Indian Sundarbans

    Directory of Open Access Journals (Sweden)

    Shilpa Sen

    2014-09-01

    Full Text Available The present study investigates the effect of different habitat attributes on brachyuran crab diversity in two different study sites in the Sundarban mangrove, India. The two sites differ in the level of anthropogenic intrusion and in the age of the mangrove forest. Seasonal changes in the environment and in brachyuran faunal abundance were recorded for three years. Species composition varied between the two habitats irrespective of season. The habitat heterogeneity and the recorded crab community was analysed by several univariate and multivariate statistical techniques. The newly replanted mangrove site showed lesser diversity than the natural one. Ocypodid crabs, mainly Uca rosea, dominated both study sites, whereas Uca triangularis was totally absent from the replanted site. Canonical correspondence analysis showed that the total acidity, total alkalinity, pH content of water, total dissolved solids, inorganic phosphate content of water, soil specific gravity, soil density and the physical constructions of the habitat play a crucial role in moderating the crab community structure. This study reveals that brachyuran crab diversity can be used as a potential indicator of the alterations of mangrove habitats.

  19. 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.

  20. Simulation of Crab Waist Collisions In DA$\\Phi$NE With KLOE-2 Interaction Region

    Energy Technology Data Exchange (ETDEWEB)

    Zobov, M. [National Inst. of Nuclear Physics (INFN), Frascati (Italy). National Lab. of Frascati (INFN-LNF); Drago, A. [National Inst. of Nuclear Physics (INFN), Frascati (Italy). National Lab. of Frascati (INFN-LNF); Gallo, A. [National Inst. of Nuclear Physics (INFN), Frascati (Italy). National Lab. of Frascati (INFN-LNF); Milardi, C. [National Inst. of Nuclear Physics (INFN), Frascati (Italy). National Lab. of Frascati (INFN-LNF); Shatilov, D. [Russian Academy of Sciences (RAS), Novosibirsk (Russian Federation). Budker Inst. of Nuclear Physics (BINP); Valishev, A. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2015-06-24

    After the successful completion of the SIDDHARTA experiment run with crab waist collisions, the electron-positron collider DAΦNE has started routine operations for the KLOE-2 detector. The new interaction region also exploits the crab waist collision scheme, but features certain complications including the experimental detector solenoid, compensating anti-solenoids, and tilted quadrupole magnets. We have performed simulations of the beam-beam collisions in the collider taking into account the real DAΦNE nonlinear lattice. In particular, we have evaluated the effect of crab waist sextupoles and beam-beam interactions on the DAΦNE dynamical aperture and energy acceptance, and estimated the luminosity that can be potentially achieved with and without crab waist sextupoles in the present working conditions. A numerical analysis has been performed in order to propose possible steps for further luminosity increase in DAΦNE such as a better working point choice, crab sextupole strength optimization, correction of the phase advance between the sextupoles and the interaction region. The proposed change of the e- ring working point was implemented and resulted in a significant performance increase.

  1. Vitellogenin2: spermatozoon specificity and immunoprotection in mud crabs.

    Science.gov (United States)

    Yang, Ya'nan; Zheng, Biqi; Bao, Chenchang; Huang, Huiyang; Ye, Haihui

    2016-09-01

    As the precursor of vitellin (Vn), vitellogenin (Vg) has initially been considered as a female-specific protein involved in vitellogenesis, while it was also present in males induced by hormones or organs manipulation. Distinct from vtg1 we previously found in female mud crab Scylla paramamosain, vtg2 was intriguingly detected in male testis under normal physiological conditions in this study. Sequence analysis showed that vtg2 and vtg1 were actually two isoforms of Vg caused by different types of alternative splicing. PCR and in situ hybridization analysis revealed that vtg2 was localized only in the testicular spermatozoa, while Vn was detected in both the spermatozoa of the testis and seminal vesicle. Therefore, we speculated that Vn was initially translated in testicular spermatozoa, then migrated with spermatozoa, and finally stored in the seminal vesicle, where spermatozoa gradually accomplished maturation. We presumed that vtg2/Vn might act as an immune-relevant molecule in the male reproduction system. In the subsequent experiment, the expression of vtg2/Vn in testis was significantly induced in response to lipopolysaccharide (LPS) and lipoteichoic acid (LTA) injection at both transcriptional and translational levels. In the light of the results presented above, we deemed that vtg2/Vn is a novel candidate of immune-relevant molecules involved in immunoprotection during the spermatozoon maturation, and this research helps to open a new avenue for further exploring the role of Vg. © 2016 Society for Reproduction and Fertility.

  2. 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.

  3. UV Timing and Spectroscopy of the Crab Nebula Pulsar

    Science.gov (United States)

    Gull, Theodore R.; Lunqvist, Peter; Sollerman, Jesper; Lindler, Don; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    We have used the Hubble Space Telescope and Space Telescope Imaging Spectrograph to obtain Near Ultraviolet (NUV) (1600-3200 Angstroms) and Far Ultraviolet (FUV) (1140-1720 Angstroms) spectra and pulse profiles of the Crab Nebula's pulsar. The pulse period agrees well with the radio predictions. The NUV and FUV pulse profiles are little changed from the visible wavelength profile. Spectra obtained with the Nordic Optical Telescope were combined with the UV spectra for full coverage from 1140-9250Angstoms. Dereddening the spectrum with a standard extinction curve achieves a flat spectrum for E(B-V)=0.52, R=3.1. Lyman alpha absorption indicates a column density of 3.0=/-0.5 x 10(exp 21) cm -2, consistent with the E(B-V) of 0.52. The dereddened spectrum can be fitted by a power law with spectral index alpha=0.11+/-0.04. A broad, blueshifted absorption is seen in CIV (1550Angstroms), reaching a velocity of about 2500 kilometer per second.

  4. The radio-gamma time delay of the Crab pulsar.

    Science.gov (United States)

    Masnou, J. L.; Agrinier, B.; Barouch, E.; Comte, R.; Costa, E.; Christy, J. C.; Cusumano, G.; Gerardi, G.; Lemoine, D.; Mandrou, P.; Massaro, E.; Matt, G.; Mineo, T.; Niel, M.; Olive, J. F.; Parlier, B.; Sacco, B.; Salvati, M.; Scarsi, L.

    1994-10-01

    Gamma-ray observations of the pulsar of the Crab nebula, PSR0531+21, have been performed in the low energy range (0.15-4.0 MeV) with FIGARO II, a large area balloon borne NaI(Tl) detector, during two flights performed on 1986 July 11 and 1990 July 9. A Kernel estimator built from the phases of the individual gamma-ray arrival times has allowed an accurate derivation of the radio-gamma time delay from those short duration gamma-ray observations. The gamma-ray pulse is found ahead of the radio pulse by 600+/-145μs and 375+/-148μs for the 1986 and 1990 observations respectively. Both radio-gamma delays could be attributed to variability of the interstellar dispersion since dispersion measures are available from radio measurements respectively two months before the 1986 flight and six days after the 1990 flight. An alternative explanation, particularly from the 1990 observation, could be that maximum gamma-ray and radio emissions originate from spatially different regions of the magnetosphere, distant by about 100 km.

  5. 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 ...

  6. 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

  7. 40 CFR 408.40 - Applicability; description of the non-remote Alaskan crab meat processing subcategory.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 28 2010-07-01 2010-07-01 true Applicability; description of the non-remote Alaskan crab meat processing subcategory. 408.40 Section 408.40 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Remote Alaskan Crab Meat Processing Subcategory § 408.40 Applicability...

  8. Insular species of Afrotropical freshwater crabs (Crustacea: Decapoda: Brachyura: Potamonautidae and Potamidae) with special reference to Madagascar and the Seychelles

    NARCIS (Netherlands)

    Cumberlidge, N.

    2008-01-01

    The evolutionary relationships between island and mainland faunas of the 24 species of insular freshwater crabs in the Afrotropical region are reviewed in the light of phylogenetic studies. Twenty insular species of freshwater crabs are endemic, and four are also found on the neighboring mainland of

  9. Shell occupation and microhabitat use by hermit crabs (Decapoda: Anomura on Fortaleza beach, Ubatuba, São Paulo

    Directory of Open Access Journals (Sweden)

    Giuliano Buzá Jacobucci

    2009-06-01

    Full Text Available Most species of hermit crabs use the empty shells of gastropods as mobile shelters. The variation of shell availability in different microhabitats can reduce competitive interactions between sympatric species, favoring their coexistence. This work aimed to characterize the occupation of gastropod shells by three species of hermit crabs, and assessing the availability of shells and evaluating the use of microhabitats crabs and gastropods in an infralitoral area on the north coast of São Paulo state. For this purpose, transect lines were established and all hermit crabs, gastropods and empty shells found were collected, recording the type of microhabitat used. In a sub-sample, the hermit crabs were identified and classified into reproductive categories. The shells used by the crabs were identified and evaluated according to physical damage and incrustation. Three species of hermit crabs (Paguristes tortugae, Pagurus brevidactylus and Pagurus criniticornis were recorded, using 15 species of gastropod shells and one of scaphopod (Dentalium sp.. Physical damage and incrustation of shells were significantly different among the hermit crab species. Considering microhabitat use, P. tortugae and P. brevidactylus were mainly found in calcareous algae, while P. criniticornis mainly occurred in sand substrate. Despite the differences in shell and microhabitat use, the high resource overlap, especially by the pagurids, indicates that competitive interactions are important regulatory factors for these populations.

  10. 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.

  11. 78 FR 15677 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Science.gov (United States)

    2013-03-12

    ...-BC25 Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab... Amendment 42 to the Fishery Management Plan for Bering Sea/Aleutian Islands King and Tanner Crabs (FMP) for..., standardize reporting across participants, and reduce costs associated with the data collection. This action...

  12. Seasonal variations in the volume of the haemolymph and body weight of the horseshoe crab, Tachypleus gigas (Muller)

    Digital Repository Service at National Institute of Oceanography (India)

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

    whereas, minimum (30 ml) in higher salinities during summer and post flood periods. The body weight of the crab was found to be affectEd. by the fluctuations in salinity. During flood period (October-November) average body weight of the crab increas...

  13. Mercury burdens in Chinese mitten crabs (Eriocheir sinensis) in three tributaries of southern San Francisco Bay, California, USA

    Science.gov (United States)

    Hui, C.A.; Rudnick, D.; Williams, E.

    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. ?? 2004 Elsevier Ltd. All rights reserved.

  14. Edible Crabs “Go West”: Migrations and Incubation Cycle of Cancer pagurus Revealed by Electronic Tags

    Science.gov (United States)

    Hunter, Ewan; Eaton, Derek; Stewart, Christie; Lawler, Andrew; Smith, Michael T.

    2013-01-01

    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. PMID:23734180

  15. Physicochemical properties of double-stranded RNA used to discover a reo-like virus from blue crab Callinectes sapidus.

    Science.gov (United States)

    Bowers, Holly A; Messick, Gretchen A; Hanif, Ammar; Jagus, Rosemary; Carrion, Lee; Zmora, Oded; Schott, Eric J

    2010-12-07

    Mortality among blue crab Callinectes sapidus in soft shell production facilities is typically 25% or greater. The harvest, handling, and husbandry practices of soft shell crab production have the potential to spread or exacerbate infectious crab diseases. To investigate the possible role of viruses in soft shell crab mortalities, we took advantage of the physicochemical properties of double-stranded RNA (dsRNA) to isolate a putative virus genome. Further characterization confirmed the presence of a reo-like virus that possesses 12 dsRNA genome segments. The virus was present in >50% of dead or dying soft shell crabs, but fewer than 5% of healthy hard crabs. Injection of the virus caused mortality and resulted in the appearance of viral RNA and virus inclusions in hemocytes. The genome of the virus was partially sequenced and the information used to develop a reverse transcription polymerase chain reaction (RT-PCR) assay that is able to detect the virus genome in as little as 7.5 pg of total RNA. The molecular tools developed during this study will allow us to quantify prevalence of the blue crab reo-like virus in captive (soft shell facilities, aquaculture operations) and wild populations and facilitate understanding of the role this virus has in blue crab life history.

  16. 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...

  17. 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.

  18. 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.

  19. Occurrence of plastic debris in the stomach of the invasive crab Eriocheir sinensis.

    Science.gov (United States)

    Wójcik-Fudalewska, Dagmara; Normant-Saremba, Monika; Anastácio, Pedro

    2016-12-15

    The Chinese mitten crab is known as a pest causing damage to fishing gears and fish. On the other hand, this highly invasive species is considered a delicacy by Asian migrants and therefore commercially fished and sold in many countries. The ingestion of plastic by the Chinese mitten crab Eriocheir sinensis from the Baltic coastal waters (Poland) and the Tagus Estuary (Portugal) was studied based on stomach content analysis. As many as 13% of the 302 analysed males and females (38.07-89.07mm carapace width) from both regions, contained microplastic in the form of strands and balls. Most of them were transparent. Ingested plastic particles were identified as fragments of fishing gears. Contamination with plastic may have a negative impact on this species as well as on higher trophic levels feeding on crabs. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. An equivalent circuit model and power calculations for the APS SPX crab cavities.

    Energy Technology Data Exchange (ETDEWEB)

    Berenc, T. (Accelerator Systems Division (APS))

    2012-03-21

    An equivalent parallel resistor-inductor-capacitor (RLC) circuit with beam loading for a polarized TM110 dipole-mode cavity is developed and minimum radio-frequency (rf) generator requirements are calculated for the Advanced Photon Source (APS) short-pulse x-ray (SPX) superconducting rf (SRF) crab cavities. A beam-loaded circuit model for polarized TM110 mode crab cavities was derived. The single-cavity minimum steady-state required generator power has been determined for the APS SPX crab cavities for a storage ring current of 200mA DC current as a function of external Q for various vertical offsets including beam tilt and uncontrollable detuning. Calculations to aid machine protection considerations were given.

  1. 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.

  2. 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.

  3. Analyses of 476 MHz and 952 MHz Crab Cavities for JLAB Electron Ion Collider

    Energy Technology Data Exchange (ETDEWEB)

    Park, HyeKyoung [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Old Dominion Univ., Norfolk, VA (United States); Castilla, Alejandro [Old Dominion Univ., Norfolk, VA (United States); Delayen, Jean R. [Old Dominion Univ., Norfolk, VA (United States); De Silva, Subashini U. [Old Dominion Univ., Norfolk, VA (United States); Morozov, Vasiliy [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2016-05-01

    The Center for Accelerator Science at Old Dominion University has designed, fabricated and successfully tested a crab cavity for Electron Ion Collider at Jefferson Lab (JLEIC) [1]. This proof-of-principle cavity was based on the earlier MEIC design which used 748.5 MHz RF system. The updated JLEIC (called MEIC earlier) design [2] utilizes the components from PEP-II. It results in the change on the bunch repetition rate of stored beam to 476.3 MHz. The ion ring collider will eventually require 952.6 MHz crab cavities. This paper will present the analyses of crab cavities of both 476 MHz and 952 MHz options. It compares advantages and disadvantages of the options which provide the JLEIC design team important technical information for a system down selection.

  4. Double Quarter Wave Crab Cavity Field Profile Analysis and Higher Order Mode Characterization

    Energy Technology Data Exchange (ETDEWEB)

    Marques, Carlos [Brookhaven National Lab. (BNL), Upton, NY (United States). Accelerator R and D Div.; Stony Brook Univ., NY (United States). Physics and Astronomy Dept.; Xiao, B. P. [Brookhaven National Lab. (BNL), Upton, NY (United States). Accelerator R and D Div.; Belomestnykh, S. [Brookhaven National Lab. (BNL), Upton, NY (United States). Accelerator R and D Div.; Stony Brook Univ., NY (United States). Physics and Astronomy Dept.

    2014-06-01

    The Large Hadron Collider (LHC) is underway for a major upgrade to increase its luminosity by an order of magnitude beyond its original design specifications. This novel machine configuration known as the High Luminosity LHC (HL-LHC) will rely on various innovative technologies including very compact and ultra-precise superconducting crab cavities for beam rotation. A double quarter wave crab cavity (DQWCC) has been designed at Brookhaven National Laboratory for the HL-LHC. This cavity as well as the structural support components were fabricated and assembled at Niowave. The field profile of the crabbing mode for the DQWCC was investigated using a phase shift bead pulling technique and compared with simulated results to ensure proper operation or discover discrepancies from modeled results and/or variation in fabrication tolerances. Higher-Order Mode (HOM) characterization was also performed and correlated with simulations.

  5. When a repellent becomes an attractant: harmful saponins are kairomones attracting the symbiotic Harlequin crab.

    Science.gov (United States)

    Caulier, Guillaume; Flammang, Patrick; Gerbaux, Pascal; Eeckhaut, Igor

    2013-01-01

    Marine organisms have developed a high diversity of chemical defences in order to avoid predators and parasites. In sea cucumbers, saponins function as repellents and many species produce these cytotoxic secondary metabolites. Nonetheless, they are colonized by numerous symbiotic organisms amongst which the Harlequin crab, Lissocarcinus orbicularis, is one of the most familiar in the Indo-Pacific Ocean. We here identify for the first time the nature of the molecules secreted by sea cucumbers and attracting the symbionts: saponins are the kairomones recognized by the crabs and insuring the symbiosis. The success of this symbiosis would be due to the ability that crabs showed during evolution to bypass the sea cucumber chemical defences, their repellents becoming powerful attractants. This study therefore highlights the complexity of chemical communication in the marine environment.

  6. 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.

  7. Effect of Microplastic on the Gills of the Shore Crab Carcinus maenas.

    Science.gov (United States)

    Watts, Andrew J R; Urbina, Mauricio A; Goodhead, Rhys; Moger, Julian; Lewis, Ceri; Galloway, Tamara S

    2016-05-17

    Microscopic plastic debris (microplastics, consumption after 1 h of exposure, returning to normal levels after 16 h. Ion exchange was also affected, with a small but significant decrease in hemolymph sodium ions and an increase in calcium ions after 24 h post-exposure. To further asses the effects on osmoregulation, we challenged crabs with reduced salinity after microplastic exposure. Neither microspheres nor natural sediments altered the crab's response to osmotic stress regardless of plastic concentration added. Carboxylated (COOH) and aminated (NH2) polystyrene microspheres were distributed differently across the gill surface, although neither had a significant adverse impact on gill function. These results illustrate the extent of the physiological effects of microplastics compared to the physiological resilience of shore crabs in maintaining osmoregulatory and respiratory function after acute exposure to both anthropogenic plastics and natural particles.

  8. 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

  9. The Hyperglycemic Effect of Melatonin in the Chinese Mitten Crab, Eriocheir sinensis

    Science.gov (United States)

    Yang, Xiaozhen; Xu, Minjie; Huang, Genyong; Zhang, Cong; Pang, Yangyang; Yang, Zhigang; Cheng, Yongxu

    2018-01-01

    Melatonin has been identified in a variety of invertebrate species, but its function is not as well understood as in crustaceans. The effects of melatonin on hemolymph glucose levels and tissue carbohydrate metabolism in the Chinese mitten crab, Eriocheir sinensis, were fully investigated in this study. Moreover, whether the eyestalk (an important endocrine center in invertebrate species) involves in this process or not, also were clarified. Analysis revealed that eyestalk ablation, especially bilateral, caused a significant decrease in the hemolymph glucose level. Moreover, injection of melatonin induced hyperglycemia in a dose-dependent manner both in intact and ablated crabs. Based on the expression of CHH mRNA in the 10 different tissues, eyestalk, thoracic ganglion, intestinal tract and hemolymph were selected to estimate the effect of melatonin on the expression of CHH mRNA. Bilateral eyestalk ablation caused a significant increase in the expression of CHH mRNA in the thoracic ganglion, intestinal tract and hemolymph compared with the controls. In addition, injection of melatonin into intact or ablated crabs elevated the CHH mRNA level in the eyestalk, thoracic ganglion and intestinal tract tissues compared with controls. The hemolymph CHH mRNA after melatonin injection was elevated only in ablated crabs. Administration of melatonin resulted in a significant decrease in total carbohydrates and glycogen levels with an increase in phosphorylase activity levels in the hepatopancreas and muscle in intact and ablated crabs. Our findings demonstrated that melatonin can induce hyperglycemic effects in both intact and ablated crabs, suggesting that this effect is probably not mediated solely via eyestalk. PMID:29618988

  10. The Hyperglycemic Effect of Melatonin in the Chinese Mitten Crab, Eriocheir sinensis

    Directory of Open Access Journals (Sweden)

    Xiaozhen Yang

    2018-03-01

    Full Text Available Melatonin has been identified in a variety of invertebrate species, but its function is not as well understood as in crustaceans. The effects of melatonin on hemolymph glucose levels and tissue carbohydrate metabolism in the Chinese mitten crab, Eriocheir sinensis, were fully investigated in this study. Moreover, whether the eyestalk (an important endocrine center in invertebrate species involves in this process or not, also were clarified. Analysis revealed that eyestalk ablation, especially bilateral, caused a significant decrease in the hemolymph glucose level. Moreover, injection of melatonin induced hyperglycemia in a dose-dependent manner both in intact and ablated crabs. Based on the expression of CHH mRNA in the 10 different tissues, eyestalk, thoracic ganglion, intestinal tract and hemolymph were selected to estimate the effect of melatonin on the expression of CHH mRNA. Bilateral eyestalk ablation caused a significant increase in the expression of CHH mRNA in the thoracic ganglion, intestinal tract and hemolymph compared with the controls. In addition, injection of melatonin into intact or ablated crabs elevated the CHH mRNA level in the eyestalk, thoracic ganglion and intestinal tract tissues compared with controls. The hemolymph CHH mRNA after melatonin injection was elevated only in ablated crabs. Administration of melatonin resulted in a significant decrease in total carbohydrates and glycogen levels with an increase in phosphorylase activity levels in the hepatopancreas and muscle in intact and ablated crabs. Our findings demonstrated that melatonin can induce hyperglycemic effects in both intact and ablated crabs, suggesting that this effect is probably not mediated solely via eyestalk.

  11. The effects of a competitor on the foraging behaviour of the shore crab Carcinus maenas.

    Directory of Open Access Journals (Sweden)

    Leela J Chakravarti

    Full Text Available Optimal Diet Theory suggests that individuals make foraging decisions that maximise net energy intake. Many studies provide qualitative support for this, but factors such as digestive constraints, learning, predation-risk and competition can influence foraging behaviour and lead to departures from quantitative predictions. We examined the effects of intraspecific competition within a classic model of optimal diet--the common shore crab, Carcinus maenas, feeding on the mussel, Mytilus edulis. Unexpectedly, we found that breaking time (Tb, eating time (Te, and handling time (Th all decreased significantly in the presence of a conspecific. Reduced handling time in the presence of a competitor resulted in an increased rate of energy intake, raising the question of why crabs do not always feed in such a way. We suggest that the costs of decreased shell breaking time may be increased risk of claw damage and that crabs may be trading-off the potential loss of food to a competitor with the potential to damage their claw whilst breaking the shell more rapidly. It is well documented that prey-size selection by crabs is influenced by both the risk of claw damage and competition. However, our results are the first to demonstrate similar effects on prey handling times. We suggest that crabs maximise their long-term rate of energy intake at a scale far greater than individual foraging events and that in order to minimise claw damage, they typically break shells at a rate below their maximum. In the presence of a competitor, crabs appear to become more risk-prone and handle their food more rapidly, minimising the risk of kleptoparasitism.

  12. 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.

  13. 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

  14. Effects of Crab Cavities' Multipole Content in an Electron-Ion Collider

    Energy Technology Data Exchange (ETDEWEB)

    Satogata, Todd J. [Jefferson Lab., Newport News, VA (United States); Morozov, Vasiliy [Jefferson Lab., Newport News, VA (United States); Delayen, Jean R. [Old Dominion Univ., Norfolk, VA (United States); Jefferson Lab., Newport News, VA (United States); Castillo, Alejandro [Old Dominion Univ., Norfolk, VA (United States)

    2015-09-01

    The impact on the beam dynamics of the Medium Energy Electron-Ion Colider (MEIC) due to the multipole content of the 750 MHz crab cavity was studied using thin multipole elements for 6D phase space particle tracking in ELEGANT. Target values of the sextupole component for the cavity’s field expansion were used to perform preliminary studies on the proton beam stability when compared to the case of pure dipole content of the rf kicks. Finally, important effects on the beam sizes due to non-linear components of the crab cavities’ fields were identified, and some criteria for their future study were proposed.

  15. New record of the sympatric distribution of two Asian species of the horseshoe crab

    Digital Repository Service at National Institute of Oceanography (India)

    Chatterji, A.

    distribution of two Asian species of the horses... http://www.ias.ac.in/currsci/sep25/articles14.htm 1 of 3 2/11/05 9:47 AM New record of the sympatric distribution of two Asian species of the horseshoe crab The geographical distribution of four extant species... swampy areas. In Orissa (Kirtania, Balramgari, Paradeep, Khairnasi and Gopalpur), the population of the horseshoe crab showed only the presence of Tachypleus gigas (Müller). New record of the sympatric distribution of two Asian species of the horses...

  16. Search of a cyclotron line at 70 keV from Crab Nebula

    International Nuclear Information System (INIS)

    Ubertini, P.; Bazzano, A.; La Padula, C.D.; Polcaro, V.F.

    1980-01-01

    An observation of Crab Nebula was made during a transmediterranean balloon flight launched on August 26, 1979 from Milo Base. The hard x-ray experiment carried a payload consisting of two multiwire proportional counters having a geometric area of 900 cm 2 each. A single transit scan of the source was performed on the Crab Nebula region at a float altitude of 2.9 mbs. The preliminary results indicate the existence of an excess flux between 64 - 76 keV above the expected value of Esup(-2.0) power law

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

    DEFF Research Database (Denmark)

    Dunn, Paul; Shanks, Alan

    2012-01-01

    females are finding large enough mates. Females were collected from three Oregon fishing ports, dissected, and checked for evidence of mating. Captured male and female crabs were also measured to estimate population size distributions. The majority of female crabs examined (69%) mated in the collection...... (carapace width, 160-169 mm) showed high mating success (84% Mated in the collection year, 95% could have produced viable eggs). These numbers compare favorably with a similar survey conducted in northern California, in which 69% of molting females had mated. We conclude from the data that molting females...... in these Oregon fishing ports are finding mates successfully, regardless of size....

  18.  The diversity of horseshoe crabs - protecting an endangered resource

    DEFF Research Database (Denmark)

    Funch, Peter; Cong, Nguyen Van; Intanai, Itsara

    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...... for eel and conch on the Atlantic Coast, and migrating shorebirds depend on their eggs for food. We recently initiated a research project to investigate and compare the physiology and genetic variation in all four species of horseshoe crabs worldwide. We intend to analyze the DNA of the horseshoe crabs...

  19. Statistical properties of giant pulses from the Crab pulsar

    Science.gov (United States)

    Popov, M. V.; Stappers, B.

    2007-08-01

    Aims:We have studied the statistics of giant pulses from the Crab pulsar for the first time with particular reference to their widths. Methods: We have analyzed data collected during 3.5 h of observations conducted with the Westerbork Synthesis Radio Telescope operated in a tied-array mode at a frequency of 1200 MHz. The PuMa pulsar backend provided voltage recording of X and Y linear polarization states in two conjugate 10 MHz bands. We restricted the time resolution to 4 μs to match the scattering on the interstellar inhomogeneities. Results: In total about 18000 giant pulses (GP) were detected in full intensity with a threshold level of 6σ. We analyzed cumulative probability distribution (CPD) of giant pulse energies for groups of GPs with different effective widths in the range 4 to 65 μs. The CPDs were found to manifest notable differences for the different GP width groups. The slope of a power-law fit to the high-energy portion of the CPD evolves from -1.7 to -3.2 when going from the shortest to the longest GPs. There are breaks in the CPD power-law fits indicating flattening at low energies with indices varying from -1.0 to -1.9 for the short and long GPs, respectively. The GPs with a stronger peak flux density were found to be of shorter duration. We compare our results with previously published data and discuss the importance of these peculiarities in the statistical properties of GPs for the theoretical understanding of the emission mechanism responsible for GP generation.

  20. Effects of acidifying ocean conditions on growth and survival of two life stages of the blue crab, Callinectes sapidus.

    Science.gov (United States)

    Giltz, S.; Taylor, C.

    2016-02-01

    Blue crabs, Callinectes sapidus, begin their larval phase offshore and circulate for approximately 30 days before settling near shore. As crabs transition to the juvenile stage, they move into coastal or estuarine environments characterized by lower salinity. Presently the average pH of the ocean is 8.1, 30% down from the beginning of the industrial revolution and is forecasted to drop to 7.8 by 2100. Decreasing pH causes dissolution of calcium carbonate shells, but the overall effects on crustaceans, such as blue crabs, are unknown. This study investigated the effect of a lower pH environment on the growth, survival, carapace hardness and molt frequency of larval and juvenile blue crabs in the Northern Gulf of Mexico. Larval crabs showed delayed growth under low pH (7.8) conditions compared to crabs in a control (present day) pH (8.1) environment. Population crashes (complete mortality) were experienced in 55% of the low pH aquaria but not in any of the control aquaria, suggesting that acidification poses a mortality risk. Under low pH conditions the intermolt duration decreased in juveniles, but the body length and weight did not differ from crabs raised in the control pH. Larvae (in tanks that did not crash) and juveniles did not experience increased mortality from a lower pH, but there do appear to be sublethal effects on growth and molting that differ between life history stages.

  1. Sex Ratio And Size At First Maturity Of Blue Swimming Crab (Portunus pelagicus Salemo Island Pangkep Regency

    Directory of Open Access Journals (Sweden)

    Muh. Saleh Nurdin

    2016-03-01

    Full Text Available Blue swimming crab (Portunuspelagicus is aeconomical valuable fisheries importantcommodity  due to the high demand and availability jobs created for the fishermen. Due to their high demand blue swimming crab heavily exploited from Salemo Island. This study aimed at comparing the sex ratio and the size at first maturity of blue swimming crab caught in mangrove ecosystems, coral reefs, and seagrass. Sex ratio was analyzed using chi square test and the size at first maturity was analyzed using the Spearman-Karber formula. The results showed the sex ratio ofmales and femalessmall crab caught in every ecosystem is balanced. The size at first maturity of blue swimming crab caught in mangrove, seagrass and coral reefs, each to the male 81,08 mm, 102,36 mm and 102,87 mm in width and size of female 94,54 mm, 83,35 mm, 98,31 mm width. In a reference to government regulations, the blue male swimming crab caught in the coral reef and seagrass ecosystems have yet to size at first maturity is allowed to be captured. Keywords: blue swimming crab, sex ratio,size at first maturity, Salemo Island

  2. Development of a real-time PCR assay for detection of planktonic red king crab (Paralithodes camtschaticus (Tilesius 1815)) larvae

    Science.gov (United States)

    Jensen, Pamela C.; Purcell, Maureen K.; Morado, J. Frank; Eckert, Ginny L.

    2012-01-01

    The Alaskan red king crab (Paralithodes camtschaticus) fishery was once one of the most economically important single-species fisheries in the world, but is currently depressed. This fishery would benefit from improved stock assessment capabilities. Larval crab distribution is patchy temporally and spatially, requiring extensive sampling efforts to locate and track larval dispersal. Large-scale plankton surveys are generally cost prohibitive because of the effort required for collection and the time and taxonomic expertise required to sort samples to identify plankton individually via light microscopy. Here, we report the development of primers and a dual-labeled probe for use in a DNA-based real-time polymerase chain reaction assay targeting the red king crab, mitochondrial gene cytochrome oxidase I for the detection of red king crab larvae DNA in plankton samples. The assay allows identification of plankton samples containing crab larvae DNA and provides an estimate of DNA copy number present in a sample without sorting the plankton sample visually. The assay was tested on DNA extracted from whole red king crab larvae and plankton samples seeded with whole larvae, and it detected DNA copies equivalent to 1/10,000th of a larva and 1 crab larva/5mL sieved plankton, respectively. The real-time polymerase chain reaction assay can be used to screen plankton samples for larvae in a fraction of the time required for traditional microscopial methods, which offers advantages for stock assessment methodologies for red king crab as well as a rapid and reliable method to assess abundance of red king crab larvae as needed to improve the understanding of life history and population processes, including larval population dynamics.

  3. High Connectivity among Blue Crab (Callinectes sapidus Populations in the Western South Atlantic.

    Directory of Open Access Journals (Sweden)

    Ana Luzia Figueiredo Lacerda

    Full Text Available Population connectivity in the blue crab Callinectes sapidus was evaluated along 740 km of the Western South Atlantic coast. Blue crabs are the most exploited portunid in Brazil. Despite their economic importance, few studies report their ecology or population structure. Here we sampled four estuarine areas in southern Brazil during winter 2013 and summer 2014 in order to evaluate diversity, gene flow and structure of these populations. Nine microsatellite markers were evaluated for 213 adult crabs, with identification of seven polymorphic loci and 183 alleles. Pairwise FST values indicated low population structure ranging from -0.00023 to 0.01755. A Mantel test revealed that the geographic distance does not influence genetic (r = -0.48, and structure/migration rates confirmed this, showing that even the populations located at the opposite extremities of our covered region presented low FST and exchanged migrants. These findings show that there is a significant amount of gene flow between blue crab populations in South Brazil, likely influenced by local current dynamics that allow the transport of a high number of larvae between estuaries. Considering the elevated gene flow, the populations can be considered a single genetic stock. However, further information on population size and dynamics, as well as fishery demands and impacts at different regions, are necessary for harvest management purposes.

  4. On the misidentification of a common sandy beach crab belonging to ...

    African Journals Online (AJOL)

    The three-spot swimming crab, a common intertidal resident of sandy beaches in southern Africa, has previously been misidentified as Ovalipes punctatus (De Haan, 1833). Inspection of local specimens indicates that the valid name for this species is O. trimaculatus (De Haan, 1833).

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

    African Journals Online (AJOL)

    Biological and ecological aspects including life cycle and reproduction, feeding ecology, biotic interactions and tolerance to environmental fluctuations and pollution are discussed. The systematics and distribution of the five fiddler crab species that occur in South Africa is provided. The St Lucia estuarine lake is presented ...

  6. Burrowing and foraging activity of marsh crabs under different inundation regimes

    Science.gov (United States)

    New England salt marshes are susceptible to degradation and habitat loss as a result of increased periods of inundation as sea levels rise. Increased inundation may exacerbate marsh degradation that can result from crab burrowing and foraging. Most studies to date have focused on...

  7. Concentration of metals in shrimps and crabs from Thane-Bassein creek system, Maharashtra

    Digital Repository Service at National Institute of Oceanography (India)

    Krishnamurti, A.J.; Nair, V.R.

    Levels of Cu, Zn, Cd, Pb and Ni in shrimps and crabs from Thane-Bassein creek system, Maharashtra, India were evaluated for a period of one year and reported as baseline for future monitoring of this vital ecosystem. The pattern of concentration...

  8. 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.

    for spawning throughout the year with maximum activity during April-October at highest high tides of the full moon and November-February during new moon phases. The tidal height showed a significant correlation with the number of crabs migrating towards...

  9. [Starvation metabolism in parent Chinese mitten-handed crab (Eriocheir sinensis)].

    Science.gov (United States)

    Wen, Xiaobo; Chen, Liqiao; Ai, Chunxiang; Zhou, Zhongliang

    2002-11-01

    The experiment was conducted to study the influence of starvation on the metabolism of parent Chinese mitten-handed crab (Eriocheir sinensis) with weights of 54.59 (+/- 2.37) g under 20 (+/- 0.5) degree C during Oct. to Dec., 1998. The results showed oxygen consumption, CO2 production and ammonia-N excretion of the parent crab being starved for 30 days were 50.0%, 63.4%, and 59.1% of those of the fed crab, respectively. The course of oxygen consumption reduction could be divided into four phases: 1) from the 1st day to the 6th day, the metabolic rate decreased remarkably; 2) from the 7th day to the 15th day, the metabolic rate kept relatively stable; 3) from the 16th day to the 25th day, the metabolic rate decreased markedly again; and 4) from 26th day to 30th day (the end time of the experiment), the metabolic rate decreased most dramatically. There were only three phases during the course of CO2 production and ammonia-N excretion reduction. Meanwhile, the standard metabolism of the starved crab reduced from 4.45 to 2.36 J.g-1.h-1, and lipid was used as the first energy source in the course of starvation.

  10. The exotic crab Percnon gibbesi (H. Milne Edwards, 1853 (Decapoda, Grapsidae in the Central Mediterranean

    Directory of Open Access Journals (Sweden)

    M. Relini

    2000-09-01

    Full Text Available The grapsid crab Percnon gibbesi (H. Milne Edwards, 1853, not previously recorded in the Mediterranean, has been found by underwater observations in several localities of Linosa, Pelagie Islands, (Italy. This presence increases the list of alien Decapods in the Mediterranean, with a form which can be considered a western migrant.

  11. Determination of Heavy Metals in Crab and Prawn in Ojo Rivers Lagos, Nigeria

    Directory of Open Access Journals (Sweden)

    R. A. Olowu

    2010-01-01

    Full Text Available The level of heavy metals in crabs and prawns was investigated using Atomic Absorption Spectrophotometer. The mean concentration of copper in the crab was 1.56±0.87 µg/g; the mean concentration of zinc in the crab was also 0.64±1.96 ܖg/g. Chromium had the highest mean concentration of 8.936±35.4 µg/g while cadmium had the lowest mean of 1.66±1.82 µg/g lead was not detected. The mean concentration of heavy metals in prawn samples were follows: copper: 1.04±0.6 µg/g, cadmium: 0.07±0.08 µg/g, chromium: 4.06±7.00 µg/g and Zn 0.64±0.45 µg/g. Lead was not detected in prawn. The mean concentration of copper, cadmium and zinc in prawn was observed to be within the range NAFDAC standard for water and aquatic foods while crabs have higher mean concentration of heavy metals with the exception of zinc and copper are within the limit.

  12. Coldbox installation for HL-LHC crab cavity test in the SPS tunnel (BA6)

    CERN Multimedia

    Ordan, Julien Marius

    2018-01-01

    The Cold-box, produced by Linde Kryotechnik for the SPS crab-cavity test stand for HL-LHC, on its arrival at CERN. It wll be transported into the tunnel in horizontal position and then will have to be tilted in its operational position, on its vertical axis, before connecting it to cryogenics lines.

  13. Simulated gamma-ray pulse profile of the Crab pulsar with the Cherenkov Telescope Array

    Science.gov (United States)

    Burtovoi, A.; Zampieri, L.

    2016-07-01

    We present simulations of the very high energy (VHE) gamma-ray light curve of the Crab pulsar as observed by the Cherenkov Telescope Array (CTA). The CTA pulse profile of the Crab pulsar is simulated with the specific goal of determining the accuracy of the position of the interpulse. We fit the pulse shape obtained by the Major Atmospheric Gamma-Ray Imaging Cherenkov (MAGIC) telescope with a three-Gaussian template and rescale it to account for the different CTA instrumental and observational configurations. Simulations are performed for different configurations of CTA and for the ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana) mini-array. The northern CTA configuration will provide an improvement of a factor of ˜3 in accuracy with an observing time comparable to that of MAGIC (73 h). Unless the VHE spectrum above 1 TeV behaves differently from what we presently know, unreasonably long observing times are required for a significant detection of the pulsations of the Crab pulsar with the high-energy-range sub-arrays. We also found that an independent VHE timing analysis is feasible with Large Size Telescopes. CTA will provide a significant improvement in determining the VHE pulse shape parameters necessary to constrain theoretical models of the gamma-ray emission of the Crab pulsar. One of such parameters is the shift in phase between peaks in the pulse profile at VHE and in other energy bands that, if detected, may point to different locations of the emission regions.

  14. Novel foraging in the swash zone on Pacific sand crabs (Emerita analoga, Hippidae) by mallards

    Science.gov (United States)

    Lafferty, Kevin D.; McLaughlin, John P.; Dugan, Jenifer E.

    2013-01-01

    Mallards (Anas platyrhynchos) have been observed foraging on intertidal Pacific sand crabs (Hippidae, Emerita analoga) in the swash zone of sandy beaches around Coal Oil Point Reserve, California, and several other beaches on the west coast since at least November 2010. Unlike foraging shorebirds, Mallards do not avoid incoming swashes. Instead, the incoming swash lifts and deposits them down the beach. Shorebirds and diving ducks commonly feed on sand crabs, but sand crabs appear to be a novel behavior and food source for Mallards. Previous surveys of beaches did not report foraging Mallards on regional beaches, whereas foraging Mallards were common in contemporary (recent) surveys and anecdotal reports. Observations of this potentially new behavior were separated by as much as 1,300 km, indicating that this was not a local phenomenon. Mallards foraged singly, in pairs, and in flocks. An expansion of diet to sand crabs carries risks of exposure to surf, human disturbance, high salt intake, and transmission of acanthocephalan and trematode parasites for Mallards but has the benefit of providing a dependable source of animal protein.

  15. Early AGILE gamma-ray observations of the recent Glitch in the Crab Pulsar

    Science.gov (United States)

    Verrecchia, F.; Piano, G.; Tavani, M.; Pilia, M.; Pittori, C.; Lucarelli, F.; Bulgarelli, A.; Cardillo, M.; Fioretti, V.; Parmiggiani, N.; Striani, E.; Vercellone, S.; Donnarumma, I.; Gianotti, F.; Trifoglio, M.; Giuliani, A.; Mereghetti, S.; Caraveo, P.; Perotti, F.; Chen, A.; Argan, A.; Costa, E.; Del Monte, E.; Evangelista, Y.; Feroci, M.; Lazzarotto, F.; Lapshov, I.; Pacciani, L.; Soffitta, P.; Sabatini, S.; Vittorini, V.; Pucella, G.; Rapisarda, M.; Di Cocco, G.; Fuschino, F.; Galli, M.; Labanti, C.; Marisaldi, M.; Pellizzoni, A.; Trois, A.; Barbiellini, G.; Vallazza, E.; Longo, F.; Morselli, A.; Picozza, P.; Prest, M.; Lipari, P.; Zanello, D.; Cattaneo, P. W.; Rappoldi, A.; Colafrancesco, S.; Ferrari, A.; Paoletti, F.; Antonelli, A.; Giommi, P.; Salotti, L.; Valentini, G.; D'Amico, F.

    2017-11-01

    AGILE observed the Crab region in its spinning mode after the large glitch recently reported in the radio band (ATel #10939). At the glitch event time (T_0) the AGILE satellite was occulted by the Earth, and no observation of any relevant gamma-ray signal could be obtained by the GRID detector.

  16. Osmoregulation and acid base regulation of the Asian Horseshoe crab Carcinoscorpius rotundicauda

    DEFF Research Database (Denmark)

    Wetter, M.; Cong, N.; Nielsen, Thomas

    2008-01-01

    Horseshoe crabs are ancient chelicerate arthropods with little apparent change in their morphology over the last 150-200 million years and they are often described as ‘living fossils'. Today only four known species remain, with one species inhabiting the eastern coast of North America, while...

  17. Crabby Interactions: Fifth Graders Explore Human Impact on the Blue Crab Population

    Science.gov (United States)

    Jeffery, Tonya D.; McCollough, Cherie A.; Moore, Kim

    2016-01-01

    This article describes a two-day lesson in which fifth-grade students took on the role of marine biology scientists, using their critical-thinking and problem-solving skills to explore human impact on the blue crab ecosystem. The purpose of "Crabby Interactions" was to help students understand the impact of human activities on the local…

  18. Are fiddler crabs potentially useful ecosystem engineers in mangrove wastewater wetlands?

    Science.gov (United States)

    Penha-Lopes, Gil; Bartolini, Fabrizio; Limbu, Samwel; Cannicci, Stefano; Kristensen, Erik; Paula, José

    2009-11-01

    The effect of different organic-rich sewage concentration (0%, 20% and 60% diluted in seawater) and absence or presence of mangrove trees on the survival, bioturbation activities and burrow morphology of fiddler crabs species was assessed. After 6 months, males of both species always showed higher survival ( approximately 80%) when compared to females ( approximately 20%). Crabs inhabiting pristine conditions achieved higher survival (67-87%) than those living in sewage-exposed mesocosms (40-71%). At 60% sewage loading, fiddler crabs processed less sediment (34-46%) during feeding and excavated slightly more sediment (45-80%) than at pristine conditions. While percent volume of the burrow chambers increased (13-66%) at contaminated mesocosms for both vegetation conditions, burrows were shallower (approximately 33%) in bare cells loaded with sewage. The results show that fiddler crabs presented moderate mortality levels in these artificial mangrove wetlands, but mainly in sewage impacted cells. However, they still function as ecosystem engineers through bioturbation activities and burrow construction.

  19. 50 CFR 600.1103 - Bering Sea and Aleutian Islands (BSAI) Crab species program.

    Science.gov (United States)

    2010-10-01

    ... harvest of crab, from each reduction endorsement fishery and from the Norton Sound fishery during the most... more reduction endorsement fisheries, regardless of whether it is also endorsed for the Norton Sound... history of the bidder's -reduction/history vessel. Norton Sound fishery means the non-reduction fishery...

  20. Facultative Parasitism by the Bivalve Kurtiella pedroana in the Mole Crab Emerita analoga.

    Science.gov (United States)

    Bhaduri, R N; Valentich-Scott, P; Hilgers, M S; Singh, R; Hickman, M E; Lafferty, K D

    2017-12-01

    Evolutionary transitions to parasitism are rare. In this study, we documented a potential step toward parasitism in the commensal clam Kurtiella pedroana (Bivalvia: Galeommatoidea). Galeommatoideans are known commensals of various invertebrates, including crustaceans. Emerita analoga (Decapoda: Hippidae) is an abundant intertidal mole crab inhabiting Pacific coast beaches in North and South America. Mole crabs collected from Monterey Bay, California, were measured and examined externally and internally for associated molluscs. Out of the 520 mole crabs, 37 large female individuals harbored 49 clams (prevalence of 7.11% and mean intensity of 1.3). Forty-one ectocommensal clams were attached by their byssal threads to the inside of the gill chambers or to the lateroventral surfaces. However, our key finding was 8 clams that lacked byssal threads and were living in the hemocoel of 6 crabs. These internal clams were smaller than the ectocommensals. Because these internal clams lacked access to their normal food, we hypothesize they might have fed on hemolymph as would a parasite. Clam larvae have no obvious exit from the hemocoel, implying that endoparasitism is a dead-end for K. pedroana. Regardless, facultative parasitism in a free-living or an ectocommensal is uncommon and suggests a pathway to parasitism.

  1. [Hermit crabs (Anomura: Paguroidea) distribution patterns in the Colombian Caribbean Sea].

    Science.gov (United States)

    Martínez Campos, Bibian; Hernando Campos, Néstor; Bermúdez Tobón, Adriana

    2012-03-01

    Hermit crabs represent the marine life in the Colombian Caribbean, and are important for the dynamic equilibrium maintenance in ecosystems, the ecological interactions and their impact on food web stability. Generally, in order to come up with some conservation strategies, strong bio-geographical information is needed for poll cies definition. With this aim, this study analyzed the distribution patterns of hermit crabs in the Colombian Caribbean Sea. through classification and spatial ordination multivariate analyses, using historical records from years 1916 to 2006. Besides, the world distribution of Colombian species and their geographic affinity in the Caribbean and Western Atlantic were identified. The results show deep differences between coastal and continental slope faunas, and latitudinal differences in the assemblages, with the identification of three groups: Northeast. Center and Southwest. The differences in faunal composition that support these three groups were determined. Based on maps of the Colombian marine ecosystems, it was found that the main factors affecting the distribution of hermit crabs were the Caribaná slope (depth), water-mass temperature, Guajira sea-grass beds, and particular conditions of "Coralline Archipelagos" and "Darién" eco-regions. Colombian hermit crab fauna is more related to the North Atlantic and the Antilles, than to the South Atlantic and the Gulf of Mexico. Additionally, geographical sub-provinces in which Colombia is included, these were found as transition zones among Northern and Austral subprovinces of the Greater Caribbean.

  2. Larval development in the sand crab Emerita emerita (Linnaeus, 1758) (Anomura Hippoidea), reared in the laboratory

    NARCIS (Netherlands)

    Israel, S.; Murugan, T.; Venugopalan, V.P.; Subramoniam, T.; Munuswamy, M.; Velde, G. van der

    2006-01-01

    Larval stages of the intertidal anomuran sand crab, Emerita emeritus (L., 1767) were reared in the laboratory up to the megalopa stage under conditions of 32� salinity, 25-27�C and a 12 : 12 hours light : dark cycle. A total of six zoeal stages and a megalopa stage were recorded with the average

  3. On the misidentification of a common sandy beach crab belonging to ...

    African Journals Online (AJOL)

    1992-07-09

    Jul 9, 1992 ... Whereas Retamal (1977) reported on the economic importance of this crab in Chile under the name. O. catharus, Fenucci & Boschi (1975) identified it correctly from the Province of Beunos Aires, Argentina. Acknowledgements. The research which led to this note was funded by the. Foundation for Research ...

  4. THE RADIO-2 mm SPECTRAL INDEX OF THE CRAB NEBULA MEASURED WITH GISMO

    International Nuclear Information System (INIS)

    Arendt, R. G.; George, J. V.; Staguhn, J. G.; Benford, D. J.; Fixsen, D. J.; Maher, S. F.; Moseley, S. H.; Sharp, E.; Wollack, E. J.; Devlin, M. J.; Dicker, S. R.; Korngut, P. M.; Irwin, K. D.; Jhabvala, C. A.; Miller, T. M.; Kovacs, A.; Mason, B. S.; Navarro, S.; Sievers, A.; Sievers, J. L.

    2011-01-01

    We present results of 2 mm observations of the Crab Nebula, obtained using the Goddard-IRAM Superconducting 2 Millimeter Observer (GISMO) bolometer camera on the IRAM 30 m telescope. Additional 3.3 mm observations with the MUSTANG bolometer array on the Green Bank Telescope are also presented. The integrated 2 mm flux density of the Crab Nebula provides no evidence for the emergence of a second synchrotron component that has been proposed. It is consistent with the radio power-law spectrum, extrapolated up to a break frequency of log (ν b [GHz]) = 2.84 ± 0.29 or ν b = 695 +651 -336 GHz. The Crab Nebula is well resolved by the ∼16.''7 beam (FWHM) of GISMO. Comparison to radio data at comparable spatial resolution enables us to confirm significant spatial variation of the spectral index between 21 cm and 2 mm. The main effect is a spectral flattening in the inner region of the Crab Nebula, correlated with the toroidal structure at the center of the nebula that is prominent in the near-IR through X-ray regime.

  5. Electroless nickel - phosphorus coating on crab shell particles and its characterization

    Science.gov (United States)

    Arulvel, S.; Elayaperumal, A.; Jagatheeshwaran, M. S.

    2017-04-01

    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.

  6. Shell selection and utilization in a terrestrial hermit crab, Coenobita compressus (H. Milne Edwards).

    Science.gov (United States)

    Abrams, Peter

    1978-01-01

    Shell utilization and shell selection studied in the tropical terrestrial hermit crab, Coenobita compressus (H. Milne Edwards). Three major shell related variables are examined; shell size, shell species, and shell condition. Nerita scabricosta (Lamarck) is the most commonly occupied shell, and it is also preferred over other shell species. Coenobita in the field are usually found in smaller than the preferred size of shell, and the difference between utilized and preferred shells is most pronounced in relatively small individuals. Shell size preference differs significantly between similarly sized crabs collected at different sites. There is also a preference for shells which have previously been used by other Coenobita individuals. This preference is due to shell modification by Coenobita, which increases the effective size of the shell. It is argued that the fitness of most sexually mature individuals is probably unaffected by the supply of new shells, since these are too small to be utilized. It is possible that the interaction of adult Coenobita for shells may be better described as mutualism than as competition. This illustrates the fact that a significant difference between utilized and preferred resources need not imply competition for those resources. Results indicate that the nature of intraspecific competition and population regulation in at least this terrestrial hermit crab is significantly different from these processes in marine hermit crabs.

  7. When a Standard Candle Flickers: 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 will miss RXTE, but will continue our monitoring program using Fermi/GBM, MAXI, and Swift/BAT.

  8. Surface Expression of NMDA Receptor Changes during Memory Consolidation in the Crab "Neohelice granulata"

    Science.gov (United States)

    Hepp, Yanil; Salles, Angeles; Carbo-Tano, Martin; Pedreira, Maria Eugenia; Freudenthal, Ramiro

    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…

  9. AFSC/RACE/SAP/Long: Effects of ocean acidification on blue king crab

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This is data from a laboratory experiment in which blue king crab juveniles were held at three different pHs (ambient, pH 7.8, and pH 7.5) for a year. Growth,...

  10. Influence of temperature on daily locomotor activity in the crab Uca pugilator.

    Directory of Open Access Journals (Sweden)

    Audrey M Mat

    Full Text Available Animals living in the intertidal zone are exposed to prominent temperature changes. To cope with the energetic demands of environmental thermal challenges, ectotherms rely mainly on behavioral responses, which may change depending on the time of the day and seasonally. Here, we analyze how temperature shapes crabs' behavior at 2 different times of the year and show that a transition from constant cold (13.5°C to constant warm (17.5°C water temperature leads to increased locomotor activity levels throughout the day in fiddler crabs (Uca pugilator collected during the summer. In contrast, the same transition in environmental temperature leads to a decrease in the amplitude of the daily locomotor activity rhythm in crabs collected during the winter. In other words, colder temperatures during the cold season favor a more prominent diurnal behavior. We interpret this winter-summer difference in the response of daily locomotor activity to temperature changes within the framework of the circadian thermoenergetics hypothesis, which predicts that a less favorable energetic balance would promote a more diurnal activity pattern. During the winter, when the energetic balance is likely less favorable, crabs would save energy by being more active during the expected high-temperature phase of the day-light phase-and less during the expected low-temperature phase of the day-dark phase. Our results suggest that endogenous rhythms in intertidal ectotherms generate adaptive behavioral programs to cope with thermoregulatory demands of the intertidal habitat.

  11. Territoriality and Conflict Avoidance Explain Asociality (Solitariness of the Endosymbiotic Pea Crab Tunicotheres moseri.

    Directory of Open Access Journals (Sweden)

    Louis J Ambrosio

    Full Text Available Host monopolization theory predicts symbiotic organisms inhabiting morphologically simple, relatively small and scarce hosts to live solitarily as a result of territorial behaviors. We tested this prediction with Tunicotheres moseri, an endosymbiotic crab dwelling in the atrial chamber of the morphologically simple, small, and relatively scarce ascidian Styela plicata. As predicted, natural populations of T. moseri inhabit ascidian hosts solitarily with greater frequency than expected by chance alone. Furthermore, laboratory experiments demonstrated that intruder crabs take significantly longer to colonize previously infected compared to uninfected hosts, indicating as expected, that resident crabs exhibit monopolization behaviors. While territoriality does occur, agonistic behaviors employed by T. moseri do not mirror the overt behaviors commonly reported for other territorial crustaceans. Documented double and triple cohabitations in the field coupled with laboratory observations demonstrating the almost invariable success of intruder crabs colonizing occupied hosts, suggest that territoriality is ineffective in completely explaining the solitary social habit of this species. Additional experiments showed that T. moseri juveniles and adults, when searching for ascidians use chemical cues to avoid hosts occupied by conspecifics. This conspecific avoidance behavior reported herein is a novel strategy most likely employed to preemptively resolve costly territorial conflicts. In general, this study supports predictions central to host monopolization theory, but also implies that alternative behavioral strategies (i.e., conflict avoidance may be more important than originally thought in explaining the host use pattern of symbiotic organisms.

  12. A freak twin trilobite larva of the Indian horseshoe crab Tachypleus gigas (Muller)

    Digital Repository Service at National Institute of Oceanography (India)

    Mishra, J.K.; Chatterji, A.; Parulekar, A.H.

    Early embryonic stages of a horseshoe crab Tachypleus gigas were studied using micrographs of live embryo. A freak egg showing two trilobite larvae bridged with each other was noticed on 38th day after fertilization. Morphology of this egg has been...

  13. Fecundity of the Indian Horse-shoe crab, Carcinoscorpius rotundicauda (Latreille)

    Digital Repository Service at National Institute of Oceanography (India)

    Chatterji, A.; Parulekar, A.H.

    Fecundity in the horse-shoe crab Carcinoscorpius rotundicauda ranges from 4217 to 10,982 with an average of 7438. The ova diameter varies between 1.5-2.3 mm with a model value of 1.7 mm. Number of ova per mm carapace length, per g body weight...

  14. 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

  15. Sacculina leptodiae Guér.-Gan., a parasite of three different crabs

    NARCIS (Netherlands)

    Boschma, H.

    1948-01-01

    The description of Sacculina leptodiae by Guérin-Ganivet (1911) was based on specimens infesting the crab Xantho exaratus (H. M. E.). Other specimens, identified as S. leptodiae or otherwise, have been mentioned in literature, so that the synonymy may be given as follows. Sacculina leptodiae

  16. Spatial distribution and population structure of fiddler crabs in an Indian Sundarban mangrove

    Directory of Open Access Journals (Sweden)

    Shilpa Sen

    2015-03-01

    Full Text Available Brachyuran crabs constitute the most abundant faunal component of mangrove ecosystems and support a wide range of ecosystem services. In the present study, seasonal variation of population density and biomass along with demographic categories and sex ratios of four species of fiddler crabs (Uca rosea, Uca triangularis, Uca dussumieri and Uca vocans from Jhorkhali Island in the Sundarban mangrove were studied in relation to some major environmental parameters (salinity, nutrient content, soil organic carbon, dissolved oxygen, total dissolved solute, etc. during bimonthly sampling for three consecutive years (2010-2012. Maximum population density and biomass of the ocypodid crabs were recorded during the pre-monsoonal month and minimum values during the monsoon. Different peaks in reproductive activity were observed among seasonal breeders (U. triangularis, U. dussumieri. For U. vocans, the sex ratio peaks declined during the ovigerous period. All four populations were characterized by significantly more males than females. Multiple regression analysis suggested a cumulative effect of several ecological parameters on seasonal fluctuations of the crab population. Breeding periodicity might be controlled by a combination of factors, including temperature, quality of the substratum, food availability for the adult and larval stages, and intertidal zonations.

  17. TROPHIC ACCUMULATION AND DEPURATION OF MERCURY BY BLUE CRABS (CALLINECTES SAPIDUS) AND PINK SHRIMP (PENAEUS DUORARUM).

    Science.gov (United States)

    Mercury concentrations in blue crabs (Callinectes sapidus) collected from an area of mercury-contaminated sediments in Lavaca Bay, TX, USA, are more than an order of magnitude greater than concentrations in penaeid shrimp from the same area. Laboratory feeding experiments using ...

  18. New Report of Two Species of Crabs, Cycloes granulosa and Pugettia vulgaris (Crustacea: Decapoda Collected from Korea

    Directory of Open Access Journals (Sweden)

    Yang, Kea Cheong

    2015-07-01

    Full Text Available Two species of crabs, Cycloes granulosa and Pugettia vulgaris, are described and illustrated for the first time in Korea. The former is the first species of calappoid genus Cycloes and characterized by having a minute lateral spine on the margin of carapace. The latter is a species of majoid crab and similar to P. pellucens. However, it can be distinguished by shorter rostral spines, a smaller hepatic spine, and a carapace entirely covered with short setae. In Korea the calappoid crab now includes seven species of three genera (Calappa, Mursia, and Cycloes and the majoid genus Pugettia consists of six species.

  19. The effect of different feed on the spawning performance of mud crab Scylla serrata broodstock

    Directory of Open Access Journals (Sweden)

    Bethsy J. Pattiasina

    2013-11-01

    Full Text Available Mud crab is one of the 12 aquaculture commodities of Ministry of Maritime Affairs and Fisheries. Control of reproduction to increase seed production through feed improvement, is one of the challenges and strategies in the mud crab aquaculture. Due to lack of knowledge about broodstock nutrition lead to producing rate of seeds still relatively low. This study aimed to obtain information on the kind of feed that has specific nutrient and plays a role in increasing the success of spawning and zoea survival. Mud crab of Scylla serrata with initial weight of 500.7±103.4 g, preferably under developed gonads were maintained in a fiber tank measuring length of 2.48 m, width 1.26 m, and a height of 60 cm which is partition sealed into 30×40×60 cm3 to put one crab. Tank was equipped with sand as a substrate as high as 15 cm and seawater system with flow rate of 1 L per six minutes and 25 cm high water. Treatments were consisted of: 1. PI (fresh meat fish of Decapterus sp. with dose of 5%, 2. PSC (fresh meat mixture of Decapterus sp. 1.8%, 3% of squid, and shrimp 1.2%, 3. PB (artificial feed dose of 10% of BW, each treatment was repeated three times. Parameters measured were the duration of ovarian to mature, egg diameter, hatching rate, fecundity, and zoea production. Data were analyzed using ANOVA. The quality of larval measured by survival and larval fat and protein content. The results showed that crabs treated by PI and PSC showed faster to get mature compared to PB treatment (p<0.05. Hatching rate of larvae in PSC treatment was higher compared to PI and PB treatments (p<0.05. Furthermore, all treatments did not affect egg diameter, fecundity, and the number of zoea (p>0.05. In conclusion, crab which fed fresh meat (PI and PSC could get mature earlier, and have high percentage of the larval hatching than those of fed by PB. In fact that larvae from broodstock feed of PI has survival as well as protein and fat content were higher than those of fed

  20. Demographic consequences of migratory stopover: linking red knot survival to horseshoe crab spawning abundance

    Science.gov (United States)

    McGowan, Conor P.; Hines, James E.; Nichols, James D.; Lyons, James E.; Smith, David; Kalasz, Kevin S.; Niles, Lawrence J.; Dey, Amanda D.; Clark, Nigel A.; Atkinson, Philip W.; Minton, Clive D.T.; Kendall, William

    2011-01-01

    Understanding how events during one period of the annual cycle carry over to affect survival and other fitness components in other periods is essential to understanding migratory bird demography and conservation needs. Previous research has suggested that western Atlantic red knot (Calidris canutus rufa) populations are greatly affected by horseshoe crab (Limulus polyphemus) egg availability at Delaware Bay stopover sites during their spring northward migration. We present a mass-based multistate, capturerecapture/resighting model linking (1) red knot stopover mass gain to horseshoe crab spawning abundance and (2) subsequent apparent annual survival to mass state at the time of departure from the Delaware Bay stopover area. The model and analysis use capture-recapture/resighting data with over 16,000 individual captures and 13,000 resightings collected in Delaware Bay over a 12 year period from 1997–2008, and the results are used to evaluate the central management hypothesis that red knot populations can be influenced by horseshoe crab harvest regulations as part of a larger adaptive management effort. Model selection statistics showed support for a positive relationship between horseshoe crab spawning abundance during the stopover and the probability of red knots gaining mass (parameter coefficient from the top model b = 1.71, SE = 0.46). Our analyses also supported the link between red knot mass and apparent annual survival, although average estimates for the two mass classes differed only slightly. The addition of arctic snow depth as a covariate influencing apparent survival improved the fit of the data to the models (parameter coefficient from the top model b = 0.50, SE = 0.08). Our results indicate that managing horseshoe crab resources in the Delaware Bay has the potential to improve red knot population status.

  1. Accumulation of current-use and organochlorine pesticides in crab embryos from Northern California, USA

    Science.gov (United States)

    Smalling, Kelly L.; Morgan, Steven; Kuivila, Kathryn K.

    2010-01-01

    Invertebrates have long been used as resident sentinels for assessing ecosystem health and productivity. The shore crabs, Hemigrapsus oregonensis and Pachygrapsus crassipes, are abundant in estuaries and beaches throughout northern California, USA and have been used as indicators of habitat conditions in several salt marshes. The overall objectives of the present study were to conduct a lab-based study to test the accumulation of current-use pesticides, validate the analytical method and to analyze field-collected crabs for a suite of 74 current-use and legacy pesticides. A simple laboratory uptake study was designed to determine if embryos could bioconcentrate the herbicide molinate over a 7-d period. At the end of the experiment, embryos were removed from the crabs and analyzed by gas chromatography/mass spectrometry. Although relatively hydrophilic (log KOW of 2.9), molinate did accumulate with an estimated bioconcentration factor (log BCF) of approximately 2.5. Following method validation, embryos were collected from two different Northern California salt marshes and analyzed. In field-collected embryos 18 current-use and eight organochlorine pesticides were detected including synthetic pyrethroids and organophosphate insecticides, as well as DDT and its degradates. Lipid-normalized concentrations of the pesticides detected in the field-collected crab embryos ranged from 0.1 to 4 ppm. Pesticide concentrations and profiles in crab embryos were site specific and could be correlated to differences in land-use practices. These preliminary results indicate that embryos are an effective sink for organic contaminants in the environment and have the potential to be good indicators of ecosystem health, especially when contaminant body burden analyses are paired with reproductive impairment assays.

  2. A case for the commons: The Snow Crab in the Barents.

    Science.gov (United States)

    Kaiser, Brooks A; Kourantidou, Melina; Fernandez, Linda

    2018-03-15

    Closing of the marine commons increases economic returns and slows depletion of valuable ocean resources. Rights-based management is widely used for fisheries rationalization. Regulators with sound biological and economic information can in theory set overall harvest control rules that protect the fish stocks, and manage for external costs and benefits from harvest. These may include ecosystem damages, overcapitalization in the fishery, and/or equity concerns. Regulatory efforts and related rights-based management instruments may increase the returns to fishery stakeholders but miss important challenges that are increasing under climate change. These include transboundary resource management and tradeoffs between local economic returns and Total Economic Value. The case of the valuable, yet invasive, crab species, Chionoecetes Opilio (Snow Crab) in the Barents Sea illustrates the concerns. The spread of the crab has known and unknown ecosystem and commercial fishery risks, particularly to uncertain ecosystem values. We show how the progression of the biological invasion interacts with human strategic behavior to identify limitations of management options. Open access harvesting of the species in international waters has generated a positive spillover effect by slowing the westward spread of the species to sensitive benthic ecosystems. This benefit is threatened by reclassification of the crab as a "sedentary species" (one which is not capable of leaving the seabed when harvestable (UNCLOS, 1982, article 77, part VI)). This shifts the regulatory environment for the crab in ways that exacerbate the invasion in exchange for protection of local gains. Such problems will increase in magnitude and impact as climate changes increasingly affect species' ranges. Optimal decision-making regarding profitable species in new ecosystems must incorporate how strategic institutional shifts occurring in response to the economic incentives asymmetrically affect local and global

  3. Behavioural Response Thresholds in New Zealand Crab Megalopae to Ambient Underwater Sound

    Science.gov (United States)

    Stanley, Jenni A.; Radford, Craig A.; Jeffs, Andrew G.

    2011-01-01

    A small number of studies have demonstrated that settlement stage decapod crustaceans are able to detect and exhibit swimming, settlement and metamorphosis responses to ambient underwater sound emanating from coastal reefs. However, the intensity of the acoustic cue required to initiate the settlement and metamorphosis response, and therefore the potential range over which this acoustic cue may operate, is not known. The current study determined the behavioural response thresholds of four species of New Zealand brachyuran crab megalopae by exposing them to different intensity levels of broadcast reef sound recorded from their preferred settlement habitat and from an unfavourable settlement habitat. Megalopae of the rocky-reef crab, Leptograpsus variegatus, exhibited the lowest behavioural response threshold (highest sensitivity), with a significant reduction in time to metamorphosis (TTM) when exposed to underwater reef sound with an intensity of 90 dB re 1 µPa and greater (100, 126 and 135 dB re 1 µPa). Megalopae of the mud crab, Austrohelice crassa, which settle in soft sediment habitats, exhibited no response to any of the underwater reef sound levels. All reef associated species exposed to sound levels from an unfavourable settlement habitat showed no significant change in TTM, even at intensities that were similar to their preferred reef sound for which reductions in TTM were observed. These results indicated that megalopae were able to discern and respond selectively to habitat-specific acoustic cues. The settlement and metamorphosis behavioural response thresholds to levels of underwater reef sound determined in the current study of four species of crabs, enables preliminary estimation of the spatial range at which an acoustic settlement cue may be operating, from 5 m to 40 km depending on the species. Overall, these results indicate that underwater sound is likely to play a major role in influencing the spatial patterns of settlement of coastal crab

  4. American Horshoe Crab (Limulus polyphemus) : Population Ecology within the Northern Gulf of Mexico

    Science.gov (United States)

    Carter, S. C.; Carmichael, R. H.; Estes, M. G., Jr.; McBarnes, M.

    2016-02-01

    To better understand the occurrence and population structure of horseshoe crabs in the northern Gulf of Mexico, we sampled animals on Petit Bois Island, Dauphin Island, and Fort Morgan. To determine if major life history events such as spawning, molting, or mortality occurred more frequently at certain locations and times, we counted molts, live animals (noted whether animals were alone or amplexed for spawning), and carcasses. We also tested the hypothesis that demographics of molts or carcasses found on local beaches represent nearby live animal populations by tracking the redistribution of tagged molts placed at variable distances from shore (2, 50, 100 m). Overall, our data suggested a greater occurrence of spawning adults and actively molting juveniles on Petit Bois Island compared to other sites. The number of specimens found at Dauphin Island and Fort Morgan declined since 2012, possibly due to a regional-scale change in environmental conditions. Size frequency distributions of molts and carcasses collected during 2015 were similar to values from previous studies, but showed a higher number of subadult horseshoe crab carcasses in 2015 compared to other years. Tagged molts were recovered at a rate of 2.5%, suggesting that few molts deposited in nearby waters make it to local beaches. Tagged molts were recovered at 1 - 22 days following field placement, with the majority of recovered molts found after 1 day. Because smaller crabs (<40 mm size) stay close to natal beaches when molting, their molts are most likely to wash ashore. Data provided by this study will help inform future research on horseshoe crab ecology and assess how natural and anthropogenic perturbaRons may affect horseshoe crab populaRons in the northern Gulf of Mexico.

  5. AFSC/RACE/SAP/Daly:Juvenile blue king crab cannibalism experiment conducted in the Kodiak Lab in 2014

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset is part of a laboratory experiment, which evaluated how varying prey densities (year-0 blue king crabs) and habitat type (shell and sand) affect the...

  6. Effects of perivitelline fluid obtained from Horseshoe crab on the proliferation and genotoxicity of dental pulp stem cells

    Digital Repository Service at National Institute of Oceanography (India)

    Musa, M.; Ali, K.M.; Kannan, T.P.; Azlina, A.; Omar, N.S.; Chatterji, A.; Mokhtar, K.I.

    Perivitelline fluid (PVF) of the horseshoe crab embryo has been reported to possess an important role during embryogenesis by promoting cell proliferation. This study aims to evaluate the effect of PVF on the proliferation, chromosome aberration (CA...

  7. Combined silver nanoparticles and temperature effects in the Cape River crab Potamanautes perlatus - Interactions between chemical and climatic stressors

    CSIR Research Space (South Africa)

    Walters, Chavon R

    2017-03-01

    Full Text Available The influence of silver nanoparticles (AgNPs) and temperature variation on toxicity and oxidative stress responses were investigated in the tissues of the Cape River crab Potamanautes perlatus following a seven-day exposure period. Toxicity...

  8. 75 FR 7435 - Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab Fisheries; 2010 Atlantic...

    Science.gov (United States)

    2010-02-19

    ... ] quantitative data, qualitative analyses were conducted. The participants in the commercial sector are the... marketing outlets with hopes to increase demand for their product. The loss in revenue to the red crab fleet...

  9. Introduction of a functionally novel consumer to a low diversity system: Effects of the mud crab Rhithropanopeus harrisii on meiobenthos

    Science.gov (United States)

    Lokko, Külli; Kotta, Jonne; Orav-Kotta, Helen; Nurkse, Kristiina; Pärnoja, Merli

    2018-02-01

    The Harris mud crab Rhithropanopeus harrisii recently expanded into much of the Baltic Sea. This invasion is expected to have significant effects on the structure and functioning of benthic ecosystems due to the lack of native crabs. Habitat type potentially modulates the effects as crabs are expected to behave differently in different habitats. In this study we experimentally evaluated the effect of R. harrisii on the species composition and dominance structure of shallow water meiobenthos within common habitat types of the north-eastern Baltic Sea. Among the studied environmental variables R. harrisii had by far the strongest effects on meiobenthos. The effects of R. harrisii varied among different habitats with the crab mostly modifying taxonomic composition and species abundances of meiobenthic communities on unvegetated soft bottom sediments. Our experiment also showed that boulders provided shelter for R. harrisii and thereby reduced their burrowing activity and effects on the adjacent soft bottom meiobenthos.

  10. AFSC/RACE/SAP/Foy: Effects of ocean acidification on embryo stages of 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 embryo stages of the economically important southern Tanner crab,...

  11. Total Fat, Calcium (Ca, Iron (Fe and Zinc (Zn Contents During Ecdysis process in the Crabs (Scylla serrata, Forsskal

    Directory of Open Access Journals (Sweden)

    Sri Swasthikawati

    2015-06-01

    Soxhlet method with chloroform and methanol (1:2, v/v as solvent. Atomic absorption spectrometer was used to measure calcium, iron, and zinc contents. Then, the result were analyzed using one way Anova and Duncan 5 %. The results showed that the total fat, calcium and zinc contents of soft shell crab Scylla serrata were higher and significantly different with three other treatments. It could be concluded that the ecdysis process, raised total fat, calcium and zinc contents of crab Scylla serrata. The total fat, calcium, and zinc contents of soft shell crab Scylla serrata was higher than that of hard shell crab from the same species.

  12. Sympatric three-species infection by Sacculina parasites (Cirripedia: Rhizocephala: Sacculinidae) of an intertidal grapsoid crab

    DEFF Research Database (Denmark)

    Tsuchida, Kohei; Lützen, Jørgen; Nishida, Mutsumi

    2006-01-01

    Parasitization by sacculinids (Cirripedia: Rhizocephala: Sacculinidae) induces severe modifications in morphology, behavior, and reproduction of their host crabs. To understand the mechanisms involved, it is important to have comprehensive information on their association. However, such information...

  13. AFSC/RACE/SAP/Long: Data from: Upper thermal tolerance in red and blue king crab: Sublethal and lethal effects

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains data from a series of experiments that determined the upper thermal tolerance of early benthic stage red and blue king crabs. Experiments...

  14. AFSC/RACE/SAP/Pathobiology: 2016 Bitter crab disease prevalence in Chionoecetes spp. from eastern Bering Sea upper continental slope

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains crab data from a field survey of Chionoecetes spp. collected during the 2016 NOAA/NMFS/AFSC/RACE groundfish and invertebrate resources bottom...

  15. Report of the Workshop on Blue Crab Stock Dynamics in Chesapeake Bay, December 13-15, 1982, Chesapeake Biological Laboratory

    OpenAIRE

    1983-01-01

    This workshop was convened to begin building a foundation of understanding for developing and evaluating proposed measures for the rational management of the blue crab fishery in Chesapeake Bay. Our goal was to generate a summary of knowledge of blue crab stock dynamics. Specifically, we intended to address, and hoped to estimate, the basic parameters of an exploited stock - growth, mortality, natality, migration rates, sex ratios and abundance. In one sense these objectives were simply a ...

  16. Experimental predatory behavior of the stone crab Eriphia verrucosa (Forskål, 1775 (Decapoda, Brachyura, Eriphiidae

    Directory of Open Access Journals (Sweden)

    Marta Pérez-Miguel

    2017-12-01

    Full Text Available Abstract Predatory behavior of the crab Eriphia verrucosa (Forskål, 1775 on the oyster Magallana angulata (Lamarck, 1819, the mussel Mytilus galloprovincialis Lamarck, 1819, the limpet Patella depressa Pennant, 1777, the hermit crab Clibanarius erythropus (Latreille, 1818, the gastropod Phorcus lineatus (da Costa, 1778 and the sea urchin Paracentrotus lividus (Lamarck, 1816 was experimentally studied. Taken into account that the sampled population of E. verrucosa was infected with the parasitic barnacle Sacculina eriphiae Smith, 1906, four predator categories were established regarding crab sex and parasite presence: uninfected and infected males and females, respectively. These four crab categories were fed on the six preys offered, but prey remains suggest that the crab obtains the flesh of each prey using different methods of attack. Irrespective of the prey species, uninfected females consistently presented lower percentages of crab feeding and total consumption. On average, it was found that a significantly higher percentage of crabs feed on M. galloprovincialis, P. depressa and Ph. lineatus than on the other three prey species (chi-squared test, p < 0.05. In terms of mean eaten biomass, the preys most eaten were P. lividus and P. depressa and the least eaten was C. erythropus (ANOVA test, p < 0.05. For crabs feeding on M. galloprovincialis and Ph. lineatus there was a significant positive correlation (p < 0.05 between the predator size and prey size, as well as between the predator size and total prey consumption. According to these results, potential effects of this top predator on intertidal communities are also discussed.

  17. Digestibility, nitrogen utilization, and voluntary intake of ensiled crab waste-wheat straw mixtures fed to sheep.

    Science.gov (United States)

    Abazinge, M D; Fontenot, J P; Allen, V G

    1994-03-01

    Crab waste and wheat (Triticum aestivum L.) straw mixtures, ensiled with different additives, were evaluated in metabolism and palatability trials. Crab waste and straw were mixed in proportions of 1:1, wet basis, with 20% water and different additives, and ensiled in 210-L metal drums double-lined with polyethylene bags. Thirty crossbred wethers (40 kg initial BW) were fed a 1) basal diet consisting of 75% orchardgrass (Dactylis glomerata L.) hay and 25% concentrate, 2) ensiled crab waste-wheat straw, with 16% (vol/wt) added glacial acetic acid, 3) crab waste-wheat straw ensiled with 20% dry molasses, 4) crab waste-wheat straw ensiled with 20% dry molasses and a microbial inoculant, and 5) ensiled wheat straw supplemented with urea. Apparent digestibility of DM and CP was lower (P < .05) for acetic acid-treated silages than for silages containing molasses. Nitrogen retention was higher (P < .05) for molasses-inoculant-treated silage than for the molasses-treated silage (5.4 vs 3.9 g/d). Ruminal NH3 N and blood urea N were higher (P < .05) for lambs fed the molasses-treated silages than for those receiving the acetic acid-treated crab waste mixture. Among the wethers fed crab waste silages, intake was lower (P < .01) for wethers receiving the acetic acid-treated silage than for those fed the molasses-treated mixtures. Treatment of crab waste-straw mixtures with molasses produced a palatable silage that was efficiently utilized by wethers.

  18. Recruitment patterns, low cannibalism and reduced interspecific predation contribute to high invasion success of two Pacific crabs in northwestern Europe

    Science.gov (United States)

    Geburzi, Jonas C.; Brandis, Dirk; Buschbaum, Christian

    2018-01-01

    Life-history traits and interactions with native species play an important role for the successful establishment of non-native species in new habitats. We investigated the recent successful invasion of the Pacific crabs Hemigrapsus takanoi and H. sanguineus to the southeastern North Sea coast with respect to their recruitment patterns, as well as interactions of juvenile with sub-adult individuals among the Pacific crabs and with native shore crabs Carcinus maenas. A field survey of juvenile native and introduced crab abundances (carapace width 1.4-10 mm) was conducted in the northern Wadden Sea, spanning 24 months from 2014 to 2016. The survey revealed different seasonal recruitment patterns of native C. maenas and both introduced Hemigrapsus species. Native shore crabs showed a single recruitment peak from June to July, while Hemigrapsus spp. mainly recruited from August to early September, but recruits occurred in low densities throughout the winter until the end of the following spring season. Field experiments on the effects of larger crabs on the recruitment intensity showed that recruitment of H. takanoi was enhanced by the presence of larger congeners, but remained unaffected by larger C. maenas. Recruitment of juvenile C. maenas, by contrast, was reduced by the presence of larger Hemigrapsus spp. Additional laboratory experiments revealed high rates of cannibalism on newly recruited C. maenas by subadult conspecifics as well as strong predation by larger Hemigrapsus spp. In contrast, newly recruited Hemigrapsus spp. had a much lower risk of being preyed on by subadult conspecifics and native shore crabs. Our results suggest that the timing of recruitment in combination with low intraspecific competition and reduced predation pressure by native shore crabs are crucial for the rapid and ongoing establishment of Hemigrapsus spp. in the Wadden Sea.

  19. The Effects of Fiddler Crabs (Uca sp on C/N Ratio and Redox Potential of Soil in Mangrove Ecosystems

    Directory of Open Access Journals (Sweden)

    Mulyanto Mulyanto

    2017-08-01

    Full Text Available Research has been done in Ketapang mangrove area of  Probolinggo city in months of September-November 2015. The objectives are to observe the fiddler crab community stucture and to analyze the effects of fiddler crabs on C/N ratio and redox potential of soil in mangrove ecosystems. The samples of fiddler crabs were taken during the low tides at 4 station (20 transects with sizes of 1 m2. Data of the fiddler crabs were measured from the soil digging insides the transect. The soil samples were taken from these crab holes wall (at the surface and at the depth of 20 cm, under the holes at the depth of 40 cm as well as from the locations that undwells by these animals at the same depth. The fiddler crab identified are U. Triangularis between 2 – 6 ind/m2, U paradussumieri 1 – 3 ind/m2, U perplexa 14 – 32 ind/m2, U dussumieri 12 – 27 ind/m2 and U. Tetragonon 3 – 6 ind/m2. The diversity is moderate (H = 1.7 and the dominance index was low (C = 0.37. C/N ratio soil were inhabited by fiddler crab between 6 – 14, the undwelled area were 14 – 20. Soil C/N ratio was inhabited by the fiddler crab at the surface and depth of 20 cm in average of 9 cm while at 40 cm in avergae of 12. The low of C/N ratio at surface and depth of 20 cm causing the organic matter turnover faster because the high nitorgen content. Soil potential redox (Eh the undwelled areas was found –0.647 mV, meanwhile the soil Eh in the dwelled areas was positive (0.68 till 0.87 mV. This mean, the decpmposition was occured during aerobic condition and will produce untoxic subtances.

  20. Water quality, nutrient budget, and pollutant loads in Chinese mitten crab ( Eriocheir sinensis) farms around East Taihu Lake

    Science.gov (United States)

    Cai, Chunfang; Gu, Xiaohong; Huang, Hezhong; Dai, Xiuying; Ye, Yuantu; Shi, Chenjiang

    2012-01-01

    To understand the factors causing frequent outbreaks of harmful algae blooms in the Taihu Lake, China, we studied water quality and nutrient budget in Chinese mitten crab ( Eriocheir sinensis) farm ponds in the eastern part of the lake from November 2007 to December 2009. We estimated the nitrogen (N), phosphorus (P), and chemical oxygen demand (COD) loads. Materials input and output ponds, water exchange, and applied management practices of 838.5-hm2 crab ponds were surveyed using questionnaires. Water quality of 12 ponds, which were located no more than 2 km from East Taihu Lake, were monitored. The results show that water quality in the crab ponds was better than reference data. Feeds, including corn seed, commercial feed, trash fish, and gastropod, were the major sources of N and P input in the crab ponds, contributing 88.7% and 94.9%, respectively. In total, 60.5% of N and 37.3% of P were sequestered by macrophytes, and only 15.7% and 8.5% of them were discharged as effluent. The net loads of N and P in effluent were 16.43 kg/hm2/cycle and 2.16 kg/hm2/cycle, respectively, while the COD load was -17.88 kg/hm2/cycle. This indicated that crab farming caused minor negative impact on the trophic status of the lake area, which was attenuated by macrophytes. However, wastewater purification is still necessary in crab faming.

  1. Finding refuge: The estuarine distribution of the nemertean egg predator Carcinonemertes errans on the Dungeness crab, Cancer magister

    Science.gov (United States)

    Dunn, Paul H.; Young, Craig M.

    2013-12-01

    Parasites can significantly impact ecosystems by altering the distributions and population sizes of their host organisms. Some hosts are thought to find refuge from parasitism by entering habitats where their parasites cannot survive. The nemertean worm Carcinonemertes errans is an egg predator that infects the Dungeness crab, Cancer magister, throughout the host's range. To determine if C. magister experiences a refuge from C. errans within estuarine environments, we examined the distribution of C. errans on Dungeness crabs within Oregon's Coos Bay Estuary. Year-round sampling over a three-year period also allowed us to test for temporal variation in the parasite's distribution. We found that parasite prevalence, mean intensity, and parasite density of C. errans infecting C. magister varied along a clear estuarine gradient, with crabs nearest the ocean carrying the heaviest parasite loads. Larger crabs were more heavily infected with worms, and seasonal infection patterns were observed at some sites within the bay. Crabs sampled from coastal waters near the estuary carried significantly more worms than did crabs from the bay, suggesting that the estuary is acting as a spatiotemporal parasite refuge for this important fishery species.

  2. Impacts of Off-Road Vehicles (ORVs) on Burrow Architecture of Ghost Crabs (Genus Ocypode) on Sandy Beaches

    Science.gov (United States)

    Lucrezi, Serena; Schlacher, Thomas A.

    2010-06-01

    Recreational beach use with off-road vehicles is popular, but potentially harmful from an environmental perspective. Beaches are important habitats to invertebrates such as ghost crabs of the genus Ocyopde, which excavate extensive and elaborate burrows. Ghost crabs are sensitive to human pressures and changes in burrow architecture may thus be a consequence of disturbance by vehicles—the predictive hypothesis of this article. This was tested during the austral spring and summer by comparing 305 burrow casts between beaches open and closed to vehicles in Eastern Australia. Traffic influenced burrow architecture: there were smaller crabs on vehicle-impacted beaches, and after the peak traffic period (Christmas and New Year holidays), these crabs had tunnelled deeper into the sediment on shores rutted by cars. Crabs constructed all types of previously described burrows, but, significantly, smaller crabs from vehicle-impacted beaches simplified their shapes following heavy traffic disturbance from four (I, J, Y, M) to only two types (I, Y). These data support a model of active behavioural responses to disturbance from vehicles, extending the known effects of beach traffic to impacts on behavioural traits of the beach fauna.

  3. Effect of sub- and supercritical water treatments on the physicochemical properties of crab shell chitin and its enzymatic degradation.

    Science.gov (United States)

    Osada, Mitsumasa; Miura, Chika; Nakagawa, Yuko S; Kaihara, Mikio; Nikaido, Mitsuru; Totani, Kazuhide

    2015-12-10

    This study examined the effects of sub- and supercritical water pretreatments on the physicochemical properties of crab shell α-chitin and its enzymatic degradation to obtain N,N'-diacetylchitobiose (GlcNAc)2. Following sub- and supercritical water pretreatments, the protein in the crab shell was removed and the residue of crab shell contained α-chitin and CaCO3. Prolonged pretreatment led to α-chitin decomposition. The reaction of pure α-chitin in sub- and supercritical water pretreatments was investigated separately; we observed lower mean molecular weight and weaker hydrogen bonds compared with untreated α-chitin. (GlcNAc)2 yields from enzymatic degradation of subcritical (350 °C, 7 min) and supercritical water (400 °C, 2.5 min) pretreated crab shell were 8% and 6%, compared with 0% without any pretreatment. This study shows that sub- and supercritical water pretreatments of crab shell provide to an alternative method to the use of acid and base for decalcification and deproteinization of crab shell required for (GlcNAc)2 production. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Summary of the Mini BNL/LARP/CARE-HHH Workshop on Crab Cavities for the LHC (LHC-CC08)

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Zvi,I.; Calaga, R.; Zimmermann, F.

    2008-05-01

    The first mini-workshop on crab compensation for the LHC luminosity upgrade (LHC-CC08) was held February 24-25, 2008 at the Brookhaven National Laboratory. A total of 35 participants from 3 continents and 15 institutions from around the world participated to discuss the exciting prospect of a crab scheme for the LHC. If realized it will be the first demonstration in hadron colliders. The workshop is organized by joint collaboration of BNL, US-LARP and CARE-HHH. The enormous interest in the subject of crab cavities for the international linear collider and future light sources has resulted in a large international collaboration to exchange aspects of synergy and expertise. A central repository for this exchange of information documenting the latest design effort for LHC crab cavities is consolidated in a wiki page: https://twiki.cern.ch/twiki/bin/view/Main/LHCCrabCavities. The main goal of this workshop was to define a road-map for a prototype crab cavity to be installed in the LHC and to discuss the associated R&D and beam dynamics challenges. The diverse subject of implementing the crab scheme resulted in a scientific program with a wide range of subtopics which were divided into 8 sessions. Each session was given a list of fundamental questions to be addressed and used as a guideline to steer the discussions.

  5. Evolution, insular restriction, and extinction of oceanic land crabs, exemplified by the loss of an endemic Geograpsus in the Hawaiian Islands.

    Directory of Open Access Journals (Sweden)

    Gustav Paulay

    Full Text Available Most oceanic islands harbor unusual and vulnerable biotas as a result of isolation. As many groups, including dominant competitors and predators, have not naturally reached remote islands, others were less constrained to evolve novel adaptations and invade adaptive zones occupied by other taxa on continents. Land crabs are an excellent example of such ecological release, and some crab lineages made the macro-evolutionary transition from sea to land on islands. Numerous land crabs are restricted to, although widespread among, oceanic islands, where they can be keystone species in coastal forests, occupying guilds filled by vertebrates on continents. In the remote Hawaiian Islands, land crabs are strikingly absent. Here we show that absence of land crabs in the Hawaiian Islands is the result of extinction, rather than dispersal limitation. Analysis of fossil remains from all major islands show that an endemic Geograpsus was abundant before human colonization, grew larger than any congener, and extended further inland and to higher elevation than other land crabs in Oceania. Land crabs are major predators of nesting sea birds, invertebrates and plants, affect seed dispersal, control litter decomposition, and are important in nutrient cycling; their removal can lead to large-scale shifts in ecological communities. Although the importance of land crabs is obvious on remote and relatively undisturbed islands, it is less apparent on others, likely because they are decimated by humans and introduced biota. The loss of Geograpsus and potentially other land crabs likely had profound consequences for Hawaiian ecosystems.

  6. Difference in the crab fauna of mangrove areas at a southwest Florida and a northeast Australia location: Implications for leaf litter processing

    Science.gov (United States)

    McIvor, C.C.; Smith, T. J.

    1995-01-01

    Existing paradigms suggest that mangrove leaf litter is processed primarily via the detrital pathway in forests in the Caribbean biogeographic realm whereas herbivorous crabs are relatively more important litter processors in the Indo-West Pacific. To test this hypothesis, we used pitfall traps to collect intertidal crabs to characterize the crab fauna in a mangrove estuary in southwest Florida. We also tethered mangrove leaves to determine if herbivorous crabs are major leaf consumers there. We compared the results with previously published data collected in an analogous manner from forests in northeastern Australia. The crab fauna in Rookery Bay, Florida, is dominated by carnivorous xanthid and deposit-feeding ocypodid crabs whereas that of the Murray River in northeastern Australia is dominated by herbivorous grapsid crabs. No leaves tethered at five sites in the forests in Southwest Florida were taken by crabs. This contrasts greatly with reported values of leaf removal by crabs in Australian forests of 28-79% of the leaves reaching the forest floor. These differences in the faunal assemblages and in the fate of marked or tethered leaves provide preliminary support for the hypothesis that leaf litter is in fact processed in fundamentally different ways in the two biogeographic realms.

  7. Evolution, insular restriction, and extinction of oceanic land crabs, exemplified by the loss of an endemic Geograpsus in the Hawaiian Islands.

    Science.gov (United States)

    Paulay, Gustav; Starmer, John

    2011-01-01

    Most oceanic islands harbor unusual and vulnerable biotas as a result of isolation. As many groups, including dominant competitors and predators, have not naturally reached remote islands, others were less constrained to evolve novel adaptations and invade adaptive zones occupied by other taxa on continents. Land crabs are an excellent example of such ecological release, and some crab lineages made the macro-evolutionary transition from sea to land on islands. Numerous land crabs are restricted to, although widespread among, oceanic islands, where they can be keystone species in coastal forests, occupying guilds filled by vertebrates on continents. In the remote Hawaiian Islands, land crabs are strikingly absent. Here we show that absence of land crabs in the Hawaiian Islands is the result of extinction, rather than dispersal limitation. Analysis of fossil remains from all major islands show that an endemic Geograpsus was abundant before human colonization, grew larger than any congener, and extended further inland and to higher elevation than other land crabs in Oceania. Land crabs are major predators of nesting sea birds, invertebrates and plants, affect seed dispersal, control litter decomposition, and are important in nutrient cycling; their removal can lead to large-scale shifts in ecological communities. Although the importance of land crabs is obvious on remote and relatively undisturbed islands, it is less apparent on others, likely because they are decimated by humans and introduced biota. The loss of Geograpsus and potentially other land crabs likely had profound consequences for Hawaiian ecosystems.

  8. Cas A and the Crab were not stellar binaries at death

    Science.gov (United States)

    Kochanek, C. S.

    2018-01-01

    The majority of massive stars are in binaries, which implies that many core collapse supernovae should be binaries at the time of the explosion. Here we show that the three most recent, local (visual) SNe (the Crab, Cas A and SN 1987A) were not stellar binaries at death, with limits on the initial mass ratios of q = M2/M1 ≲ 0.1. No quantitative limits have previously been set for Cas A and the Crab, while for SN 1987A we merely updated existing limits in view of new estimates of the dust content. The lack of stellar companions to these three ccSNe implies a 90 per cent confidence upper limit on the q ≳ 0.1 binary fraction at death of fb Gaia proper motion and parallax catalogues providing a powerful probe of the statistics of such binaries and their role in massive star evolution, neutron star velocity distributions and runaway stars.

  9. Search for ultrahigh energy emission from the Crab pulsar/nebula

    International Nuclear Information System (INIS)

    Dion, G.M.

    1993-02-01

    A search for steady and episodic emission of Ultra High Energy radiation from the Crab has been carried out using the CYGNUS air shower array telescope. No signal has been observed in the analysis of the data set of more than 2 x 10 8 showers with energies greater than about 10 TeV. A flux upper limit on the unpulsed steady emission above 40 TeV is 2.9 x 10 -13 cm 2 s -1 , at the 90% confidence level limit. A burst was observed for the source transit on April 28, 1989. This day had a probability of 0.71% of being a random fluctuation for the 1621 days of from the Crab region

  10. Evaluation of physical, chemical and irradiation parameters on crab shell's chitosan obtention process

    International Nuclear Information System (INIS)

    Ferreira, Maiara S.; Moura, Eduardo de; Geraldo, Aurea B.C.

    2015-01-01

    Chitin it is found in exoskeletons of crustaceans and in the cellular wall of fungi. Chitosan is obtained through the stages of deproteinization, demineralization and deacetylation. Specially, crab shells present in their composition 15-20% of chitin, 25-40% of proteins and 40-55% calcium carbonate. The demineralization step aims to reduce the inorganic ions content and is realized under hydrochloric acid dissolution. The deproteinization has the function of reducing the proteins and aminoacids by sodium hydroxide solution added to the raw material. In this work, the experimental design used to determine the best steps conditions for the production of final product - chitosan from chitin of crab shells - had been time (10, 30, 60 and 120 minutes), concentration, relation reagent solution/raw material quantity and irradiation parameters (radiation font, dose and dose rate). The results are discussed in terms of total inorganic materials and proteins quantification and of thermal analysis. (author)

  11. The Crab Nebula: High energy X-ray observation of a lunar occultation

    International Nuclear Information System (INIS)

    Staubert, R.; Kendziorra, E.; Trumper, J.; Reppin, C.; Hoffman, J.A.; Pounds, K.A.; Giles, A.B.; Morrison, L.V.

    1975-01-01

    A lunar occultation of the Crab Nebula was observed at X-ray energies above 15 keV by a scintillation counter on a Skylark rocket launched from Spain on 1974 October 7. The angular extent of the region of emission of 75 percent of the total flux between 15 and 150 keV (average photon energy 39 keV) along psoition angle 263degree is found to be 110''+25''. The offset of the centroid of the extended source is such that its projection to the west of NP 0532 is 8''plus-or-minus6''. The variation of size with energy, as found from this and other measurements, sets constraints on models for energy transfer along magnetic field lines in the Crab

  12. Design, prototyping and testing of a compact superconducting double quarter wave crab cavity

    CERN Document Server

    Xiao, Binping; Belomestnykh, Sergey; Ben-Zvi, Ilan; Calaga, Rama; Cullen, Chris; Capatina, Ofelia; Hammons, Lee; Li, Zenghai; Marques, Carlos; Skaritka, John; Verdú-Andres, Silvia; Wu, Qiong

    2015-01-01

    A novel design of superconducting Crab Cavity was proposed and designed at Brookhaven National Laboratory. The new cavity shape is a Double Quarter Wave or DQWCC. After fabrication and surface treatments, the niobium proof-of-principle cavity was cryogenically tested in a vertical cryostat. The cavity is extremely compact yet has a low frequency of 400 MHz, an essential property for service for the Large Hadron Collider luminosity upgrade. The electromagnetic properties of the cavity are also well matched for this demanding task. The demonstrated deflecting voltage of 4.6 MV is well above the requirement for a crab cavity in the future High Luminosity LHC of 3.34 MV. In this paper we present the design, prototyping and test results of the DQWCC.

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

    Science.gov (United States)

    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.

  14. Setting Up Simulations of Failure Scenarios for a Crab Cavity in the Nominal LHC

    CERN Document Server

    Yee, B

    2010-01-01

    The crab cavity (CC) represents a possible solution for the problem of the reduction of the luminosity due to a crossing angle. The CC apply a transversal kick on the beam particles that varies with the longitudinal position along the bunch in order to produce an effective head-head collision and to increase the geometry luminosity. For that reason the BE-ABP group at CERN has been performing studies for the implementation of the CC in the LHC. Because machine protection is a critical element of LHC operation, it is essential to study the failure scenarios of the superconducting crab cavity and the possible resulting damage impact and well as to find possible mitigation measures. For this purpose we set up simulation tools to model CC failures in the nominal LHC.

  15. Design, prototyping, and testing of a compact superconducting double quarter wave crab cavity

    Directory of Open Access Journals (Sweden)

    Binping Xiao

    2015-04-01

    Full Text Available We proposed a novel design for a compact superconducting crab cavity with a double quarter wave (DQWCC shape. After fabrication and surface treatments, this niobium proof-of-principle cavity was tested cryogenically in a vertical cryostat. The cavity is extremely compact yet has a low frequency of 400 MHz, an essential property for service in the Large Hadron Collider luminosity upgrade. The cavity’s electromagnetic properties are well suited for this demanding task. The demonstrated deflecting voltage of 4.6 MV is well above the required 3.34 MV for a crab cavity in the future High Luminosity LHC. In this paper, we present the design, prototyping, and results from testing the DQWCC.

  16. Evaluation of physical, chemical and irradiation parameters on crab shell's chitosan obtention process

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Maiara S.; Moura, Eduardo de; Geraldo, Aurea B.C., E-mail: maiaraferreira@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    Chitin it is found in exoskeletons of crustaceans and in the cellular wall of fungi. Chitosan is obtained through the stages of deproteinization, demineralization and deacetylation. Specially, crab shells present in their composition 15-20% of chitin, 25-40% of proteins and 40-55% calcium carbonate. The demineralization step aims to reduce the inorganic ions content and is realized under hydrochloric acid dissolution. The deproteinization has the function of reducing the proteins and aminoacids by sodium hydroxide solution added to the raw material. In this work, the experimental design used to determine the best steps conditions for the production of final product - chitosan from chitin of crab shells - had been time (10, 30, 60 and 120 minutes), concentration, relation reagent solution/raw material quantity and irradiation parameters (radiation font, dose and dose rate). The results are discussed in terms of total inorganic materials and proteins quantification and of thermal analysis. (author)

  17. The complete mitochondrial genome of the subarctic red king crab, Paralithodes camtschaticus (Decapoda, Anomura).

    Science.gov (United States)

    Kim, Sanghee; Choi, Han-Gu; Park, Joong-Ki; Min, Gi-Sik

    2013-08-01

    We determined the complete mitochondrial (mt) genome sequence of the red king crab, Paralithodes camtschaticus (Decapoda, Anomura). P. camtschaticus is one of the largest arthropods and the most expensive commercially available gourmet seafood. The genome sequence of P. camtschaticus is 16,720 bp in size and its gene content, gene order, and transcriptional polarity are almost identical to those of the hermit crab Pagurus longicarpus, which is thought to be derived from a common ancestor. However, P. camtschaticus mtDNA showed tRNA translocation in two blocks compared to that of P. longicarpus. Prior to this study, complete mt genomes of only two species of Anomura have been reported. Thus, our genomic data will provide additional information for constructing the decapod phylogeny.

  18. Shell occupation by the endemic western Atlantic hermit crab Isocheles sawayai (Diogenidae from Caraguatatuba, Brazil

    Directory of Open Access Journals (Sweden)

    MZ. Fantucci

    Full Text Available The aim of this study was to characterize the pattern of shell occupation by the hermit crab Isocheles sawayai Forest and Saint-Laurent, 1968, from the Caraguatatuba region. The percentage of shell types that were occupied and the morphometric relationships between hermit crabs and occupied shells were analyzed from systematized collections that were conducted monthly from July 2001 to June 2003. A total of 373 individuals were captured (297 males, 41 non-ovigerous females, 25 ovigerous females and 10 intersexes, occupying 17 species of gastropod shells. Stramonita haemastoma (Linnaeus, 1767 (49.87% was the significantly most occupied species (χ2 = 89.30; P 0.68 and significant (P < 0.05 correlation values, which is an important indication that in this I. sawayai population the animals occupied adequate shells. The high number of occupied shell species and relative plasticity indicated that, for the studied population, occupation is influenced by the shell availability.

  19. A New Report of Two Species of Pagurid Hermit Crabs (Crustacea: Decapoda: Anomura from Korea

    Directory of Open Access Journals (Sweden)

    Won Kim

    2014-01-01

    Full Text Available Pagurus undosus and Pagurus parvispina, collected from the East Sea by fishery trap, are newly recorded from Korean waters. Pagurus undosus is distinguished from other hermit crab by its right cheliped slightly elevated medially, and with broad ridge formed by deep depressions mesial and lateral to midline. Pagurus parvispina is distinguished from other hermit crab by its right cheliped covered with large spine and long tufts of setae. These species live in cold water areas and their geographical distribution is extended southwardly by the present study. A specimen of the former species, P. undosus, was found living in a shelter formed by a sponge, similar to that observed in Pagurus pectinatus. Descriptions and figures of these two species are provided in this paper. Currently, 27 species of the genus Pagurus are recorded in Korean fauna.

  20. Engineering Study of Crab Cavity HOM Couplers for LHC High Luminosity Upgrade

    CERN Document Server

    Park, Hyekyung; Delayen, Jean Roger; De Silva, S U; Li, Z; Nicol, T H; Capelli, Teddy; Templeton, Niklas John

    2015-01-01

    The LHC is planning to employ crab cavities for the high luminosity upgrade. Old Dominion University and SLAC National Laboratory are developing a crab cavity completed with the HOM damping couplers [1]. The HOM couplers are coaxial type and perform over broadband up to 2 GHz. The amount of extracted power requires active cooling using liquid helium. The electromagnetic study has provided expected power dissipation on the coupler. Correlations between the fabrication tolerance and its damping performance have been studied and the results are providing guidelines on how to manufacture the HOM couplers. This paper summarizes the engineering studies; mechanical strength as a part of pressure system, thermal stability, and fabrication method to ensure the required tolerance.

  1. γ-Ray-induced reciprocal translocations in spermatogonia of the crab-eating monkey (Macaca fascicularis)

    International Nuclear Information System (INIS)

    Matsuda, Y.; Tobari, I.; Yamagiwa, J.; Utsugi, T.; Kitazume, M.; Nakai, S.

    1984-01-01

    The yield of translocations induced by γ-rays in the crab-eating monkey (Macaca fascicularis) spermatogonia were studied by cytological analysis in spermatocytes derived from them. The frequencies of translocations were 0.09 per cent at 0 Gy, 1.9 per cent at 1 Gy, 2.5 per cent at 2 Gy and 1.3 per cent at 3 Gy, showing a humped dose-response curve with a peak yield around 2 Gy. No remarkable inter-seasonal or inter-animal variations in the induction of translocation were observed. The frequencies in the crab-eating monkey were significantly higher than those in the same Macaca genus, the rhesus monkey (Macaca mulatta). This inter-species difference in radiosensitivity might be affected by the condition of spermatogonial stem cells at the time of exposure to radiation, depending on the seasonal change in spermatogenetic activity. (orig.)

  2. Observations of the Crab Nebula with the Chandra X-Ray Observatory

    Science.gov (United States)

    Weisskopf, Martin C.

    2012-01-01

    The Crab Nebula and its pulsar has been the subject of a number of detailed observations with the Chandra X-ray Observatory. The superb angular resolution of Chandra s high-resolution telescope has made possible numerous remarkable results. Here we describe a number of specific studies of the Crab that I and my colleagues have undertaken. We discuss the geometry of the system, which indicates that the "inner X-ray ring", typically identified with the termination shock of the pulsar s particle wind, is most likely not in the equatorial plane of the pulsar. Other topics are the northern wisps and their evolution with time; the characterization of features in the jet to the southeast; pulse-phase spectroscopy and possible correlations with the features at other wavelengths, particularly the optical polarization; and a search for correlations of the X-ray flux with the recently-discovered gamma -ray flares.

  3. Bursts of the Crab Nebula gamma-ray emission at high and ultra-high energies

    Directory of Open Access Journals (Sweden)

    Lidvansky A.S.

    2017-01-01

    Full Text Available Characteristics of the flares of gamma rays detected from the Crab Nebula by the AGILE and Fermi-LAT satellite instruments are compared with those of a gamma ray burst recorded by several air shower arrays on February 23, 1989 and with one recent observation made by the ARGO-YBJ array. It is demonstrated that though pulsar-periodicity and energy spectra of emissions at 100 MeV (satellite gamma ray telescopes and 100 TeV (EAS arrays are different, their time structures seem to be similar. Moreover, maybe the difference between “flares” and “waves” recently found in the Crab Nebula emission by the AGILE team also exists at ultra-high energies.

  4. Identification of differentially expressed genes during the brachyurization of the Chinese mitten crab Eriocheir japonica sinensis.

    Science.gov (United States)

    Li, Peng; Zha, Jie; Sun, Hongying; Song, Daxiang; Zhou, Kaiya

    2011-10-01

    Expressed sequence tags (ESTs) obtained from two-directional suppression subtractive hybridization (SSH) of cDNA libraries derived from the pleon of the Chinese mitten crab were analyzed using mRNA subtractive hybridization. After cDNA cloning and sequencing, gene expression profiles were examined, focusing on brachyurization. We assembled 211 non-redundant ESTs from SSH library 1 (yielding 130 unique transcripts: 25 consensi, 105 singletons) and 669 from SSH library 2 (195: 51 consensi, 144 singletons). Functional analysis shows that these genes are putatively involved in various cellular processes (33%), ribosomal RNA/proteins (30%), molting (12%), signal transduction (6%), immune factor and stress proteins (6%), development (4%), energy metabolism (3%), and mitochondrial membrane protein, hormone metabolizing, and chaperone (1% each) of other organisms. Some 3% are of unknown function in SSH library 1. The results facilitate the functional study of candidate genes involved in early developmental processes, especially the regulation of brachyurization in this crab.

  5. 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

  6. Purificación de dos proteínas de Leishmania Viannia panamensis y su utilización en el diagnóstico de casos de leishmaniosis cutánea de larga evolución y difícil diagnóstico parasitológico

    Directory of Open Access Journals (Sweden)

    Sonia Agudelo

    2001-04-01

    Full Text Available

    La respuesta inmune humoral inducida por Leishmania spp, se inicia desde la etapa temprana de la infección y se mantiene hasta cuando la mayoría de los parásitos son eliminados. Los isotipos, subclases y niveles de anticuerpos que evalúan esta respuesta dependen en gran medida de la forma clínica y el estado de evolución de la enfermedad. En casos de lesiones mucosas o cutáneas de larga evolución donde la posibilidad de encontrar parásitos es baja, toma gran importancia evaluar esta respuesta humoral. Sin embargo, las técnicas serológicas existentes para detectar anticuerpos antileishmania presentan baja sensibilidad y alta reacción cruzada con parásitos de Trypanosoma cruzi, surgiendo, como una alternativa para mejorar estas pruebas, el uso de antígenos proteicos purificados (1,2. Teniendo como base los resultados obtenidos por Agudelo y col (3, quienes demostraron que las fracciones proteicas de 36 y 50 kDa de Leishmania Viannia panamensis son altamente sensibles y
    100% específicas de Leishmania, nos proponemos purificar estas proteínas a fin de utilizarlas para mejorar la sensibilidad y especificidad de pruebas serológicas que sean económicas y de ejecución práctica en zonas endémicas de leishmaniosis.

     

  7. Offspring production in three freshwater crab species (Brachyura: Pseudothelphusidae from the Amazon region and Central America

    Directory of Open Access Journals (Sweden)

    Ingo S. Wehrtmann

    2010-01-01

    Full Text Available Freshwater crabs are an important component of the fauna of limnic environments, and out of the two true freshwater crab families present in the Neotropics, Pseudothelphusidae is the most diverse. Considering the lack of information regarding reproductive features of neotropical freshwater crabs, we studied, for the first time, the fecundity and the presence of juveniles carried by females of two pseudothelphusids from the Amazon region - Kingsleya latifrons (Randall, 1840 and Kingsleya ytupora Magalhães, 1986 - and one from Central America - Potamocarcinus magnus (Rathbun, 1896. The two Kingsleya species produced relatively few (56-114 and large eggs (1.9-3.7 mm, typical for species with an abbreviated or direct development. Recently produced eggs were substantially larger in K. latifrons (mean 2.83 mm when compared to those of K. ytupora (mean 1.87 mm; however, at the end of the embryogenesis, mean egg diameter was similar in both species. Therefore, it is assumed that hatchlings in both species should have a similar size. A brief description of attached juveniles of K. ytupora is provided. The number of juveniles varied between 30 (K. ytupora and 179 (P. magnus; two size groups of juveniles were found, which indicates that the offspring cling to their mother for a prolonged period of time. There was no significant loss of eggs and juveniles; it is assumed that parental care diminishes the loss of their offspring. We compiled the available information of reproductive aspects from freshwater crabs: egg diameter was in the range of 2-3 mm, independent of female size and fecundity, and reported egg number varied between 9 and 417 eggs.

  8. Characterization of the circulating hemocytes in mud crab (Scylla olivacea) revealed phenoloxidase activity.

    Science.gov (United States)

    Mangkalanan, Seksan; Sanguanrat, Piyachat; Utairangsri, Tanatchaporn; Sritunyalucksana, Kallaya; Krittanai, Chartchai

    2014-05-01

    This study focused on an isolation and characterization of the circulating hemocytes in mud crab, Scylla olivacea. Isolation of specific cell types of hemocytes from crab hemolymph was accomplished by using 60% Percoll density gradient centrifugation. Four separated bands of the hemocytes were successfully obtained. Characterization of these isolated hemocytes by light microscope using trypan blue-rose bengal staining, rose bengal-hematoxilin staining, and phase contrast revealed four distinct types of hemocyte cells. Using their specific morphology and granularity, they were identified as hyaline cell (HC), small granular cell (SGC), large granular cell (LGC) and mixed granular cell (MGC). Transmission electron microscopy (TEM) revealed more details on specific cell size, size of cytoplasmic granule, and nuclear to cytoplasmic ratio, and confirmed the classification. Relative abundance of these cells types in the hemolymph of an adult crab were 15.50±8.22% for HC, 55.50±7.15% for SGC, 13.50±5.28% for LGC, and 15.50±3.50% for MGC. Proteomic analysis of protein expression for each specific cell types by two-dimensional electrophoresis identified two highly abundant proteins, prophenoloxidase (ProPO) and peroxinectin in LGC. Determination of phenoloxidase (PO) activity in each isolated cell types using in vitro and in situ chemical assays confirmed the presence of PO activity only in LGC. Based on an increased PO activity of crab hemolymph during the course of White Spot Syndrome Virus (WSSV) infection, these results suggest that prophenoloxidase pathway was employed for host defense mechanism against WSSV and it may link to the role of large granular hemocyte. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Scaling of olfactory antennae of the terrestrial hermit crabs Coenobita rugosus and Coenobita perlatus during ontogeny

    Directory of Open Access Journals (Sweden)

    Lindsay D. Waldrop

    2014-08-01

    Full Text Available Although many lineages of terrestrial crustaceans have poor olfactory capabilities, crabs in the family Coenobitidae, including the terrestrial hermit crabs in the genus Coenobita, are able to locate food and water using olfactory antennae (antennules to capture odors from the surrounding air. Terrestrial hermit crabs begin their lives as small marine larvae and must find a suitable place to undergo metamorphosis into a juvenile form, which initiates their transition to land. Juveniles increase in size by more than an order of magnitude to reach adult size. Since odor capture is a process heavily dependent on the size and speed of the antennules and physical properties of the fluid, both the transition from water to air and the large increase in size during ontogeny could impact odor capture. In this study, we examine two species of terrestrial hermit crabs, Coenobita perlatus H. Milne-Edwards and Coenobita rugosus H. Milne-Edwards, to determine how the antennule morphometrics and kinematics of flicking change in comparison to body size during ontogeny, and how this scaling relationship could impact odor capture by using a simple model of mass transport in flow. Many features of the antennules, including the chemosensory sensilla, scaled allometrically with carapace width and increased slower than expected by isometry, resulting in relatively larger antennules on juvenile animals. Flicking speed scaled as expected with isometry. Our mass-transport model showed that allometric scaling of antennule morphometrics and kinematics leads to thinner boundary layers of attached fluid around the antennule during flicking and higher odorant capture rates as compared to antennules which scaled isometrically. There were no significant differences in morphometric or kinematic measurements between the two species.

  10. Beating the spin-down limit on gravitational wave emission from the Crab pulsar

    OpenAIRE

    Abbott, B.; Abbott, R.; Adhikari, R.; Ajith, P.; Allen, Bruce; Allen, Gabrielle; Amin, R.; Anderson, S. B.; Anderson, W. G.; Arain, M.; Araya, M.; Armandula, H.; Armor, P.; Aso, Y.; Aston, S.

    2008-01-01

    We present direct upper limits on gravitational wave emission from the Crab pulsar using data from the first nine months of the fifth science run of the Laser Interferometer Gravitational-wave Observatory (LIGO). These limits are based on two searches. In the first we assume that the gravitational wave emission follows the observed radio timing, giving an upper limit on gravitational wave emission that beats indirect limits inferred from the spin-down and braking index of the pulsar and the e...

  11. Does ‘You Are What You Eat’ Apply to Mangrove Grapsid Crabs?

    Science.gov (United States)

    Bui, Thi Hong Hanh; Lee, Shing Yip

    2014-01-01

    In tropical mangroves, brachyuran crabs have been observed to consume high percentages of leaf litter production. However, questions concerning their ability to assimilate this low-quality food remain, as stable isotope analysis of C and N does not seem to support assimilation. Individuals of the common eastern Australian mangrove grapsid Parasesarma erythodactyla feeding on a mangrove leaf litter or mangrove+microphytobenthos diet developed a significantly higher hepatosomatic index than those with access to only sediment. Lipid biomarker analysis and feeding experiments using 13C and 15N-enriched mangrove leaf litter confirmed rapid assimilation of mangrove C and N by P. erythodactyla. Eight-week feeding experiments utilizing three food types (mangrove leaf litter, microphytobenthos and prawn muscle) established different food-specific trophic discrimination values (Δδ13C and Δδ15N) that are significantly different from those commonly applied to mixing model calculations. The mean Δδ13C(crab-mangrove) of +5.45‰ was close to the mean and median literature values for grapsid-mangrove pairs in 29 past studies (+5.2±1.8‰ and +5.6‰, respectively), suggesting that this large discrimination may generally be characteristic of detritivorous grapsid crabs. Solutions from the IsoConc mixing model using our determined trophic discrimination values suggest significantly higher and dominant contributions of mangrove C to the diet than those based on the global mean trophic discrimination values. Our results reaffirm the physiological capacity for and important mediating role of grapsid crabs in processing low-quality mangrove C in tropical estuaries, and caution against the use of global trophic discrimination values in stable isotope analysis of food-web data, especially those involving detritivores. While recent studies have questioned the trophic significance of mangrove detritus in coastal food chains, the contribution of this productive carbon source needs to

  12. Does 'you are what you eat' apply to mangrove grapsid crabs?

    Science.gov (United States)

    Bui, Thi Hong Hanh; Lee, Shing Yip

    2014-01-01

    In tropical mangroves, brachyuran crabs have been observed to consume high percentages of leaf litter production. However, questions concerning their ability to assimilate this low-quality food remain, as stable isotope analysis of C and N does not seem to support assimilation. Individuals of the common eastern Australian mangrove grapsid Parasesarma erythodactyla feeding on a mangrove leaf litter or mangrove+microphytobenthos diet developed a significantly higher hepatosomatic index than those with access to only sediment. Lipid biomarker analysis and feeding experiments using (13)C and (15)N-enriched mangrove leaf litter confirmed rapid assimilation of mangrove C and N by P. erythodactyla. Eight-week feeding experiments utilizing three food types (mangrove leaf litter, microphytobenthos and prawn muscle) established different food-specific trophic discrimination values (Δδ(13)C and Δδ(15)N) that are significantly different from those commonly applied to mixing model calculations. The mean Δδ(13)C(crab-mangrove) of +5.45‰ was close to the mean and median literature values for grapsid-mangrove pairs in 29 past studies (+5.2 ± 1.8‰ and +5.6‰, respectively), suggesting that this large discrimination may generally be characteristic of detritivorous grapsid crabs. Solutions from the IsoConc mixing model using our determined trophic discrimination values suggest significantly higher and dominant contributions of mangrove C to the diet than those based on the global mean trophic discrimination values. Our results reaffirm the physiological capacity for and important mediating role of grapsid crabs in processing low-quality mangrove C in tropical estuaries, and caution against the use of global trophic discrimination values in stable isotope analysis of food-web data, especially those involving detritivores. While recent studies have questioned the trophic significance of mangrove detritus in coastal food chains, the contribution of this productive carbon

  13. Selection of an omnivorous diet by the mangrove tree crab Aratus pisonii in laboratory experiments

    Science.gov (United States)

    Erickson, Amy A.; Feller, Ilka C.; Paul, Valerie J.; Kwiatkowski, Lisa M.; Lee, Woody

    2008-02-01

    Observational studies on leaf damage, gut content analyses, and crab behaviour have demonstrated that like numerous other mangrove and salt-marsh generalists, the mangrove tree crab Aratus pisonii feeds on a variety of food resources. This study is the first that experimentally tests feeding preferences of A. pisonii, as well as the first to test experimentally whether chemical composition of food resources is responsible for food selection. Feeding preferences were determined among a variety of plant, algal, and animal resources available in the field both in Florida and Belize, using multiple-choice feeding assays, where male and female crabs simultaneously were offered a variety of food items. To test whether chemistry of food resources was responsible for feeding preferences, chemical extracts of food resources were incorporated in an agar-based artificial food, and used in feeding assays. Results of feeding assays suggest that crabs prefer animal matter from ˜ 2.5 to 13× more than other available resources, including leaves of the red mangrove Rhizophora mangle, which contribute the most to their natural diet. Artificial feeding assays also demonstrated that chemical cues were responsible for selection of animal matter, up to 25× more than other available resources. Non-polar extracts (derived from extraction in 1:1 ethyl actetate:methanol) stimulated feeding the most, suggesting that fatty acids, triglycerides, or sterols may be important for growth, reproduction, or survival. Results for both sexes were similar across most assays. While chemical composition of food resources appears to play some role in selection, this does not discount the potential role of other factors, such as resource availability, competition, predation, or reproductive requirements in influencing feeding preferences. Bioassay-guided fractionation of extracts should aid in determining chemical constituents that play the greatest role in determining feeding preferences.

  14. Cryogenic test of double quarter wave crab cavity for the LHC High luminosity upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, B. [Brookhaven National Lab. (BNL), Upton, NY (United States); Alberty, L. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Belomestnykh, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., NY (United States); Ben-Zvi, I. [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., NY (United States); Calaga, R. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Cullen, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Capatina, O. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Hammons, L. [Brookhaven National Lab. (BNL), Upton, NY (United States); Li, Z. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Marques, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Skaritka, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Verdu-Andres, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Wu, Q. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-05-03

    A Proof-of-Principle (PoP) Double Quarter Wave Crab Cavity (DQWCC) was designed and fabricated for the Large Hadron Collider (LHC) luminosity upgrade. A vertical cryogenic test has been done at Brookhaven National Lab (BNL). The cavity achieved 4.5 MV deflecting voltage with a quality factor above 3×109. We report the test results of this design.

  15. Species and size diversity in protective services offered by coral guard-crabs

    OpenAIRE

    McKeon, C. Seabird; Moore, Jenna M.

    2014-01-01

    Coral guard-crabs in the genus Trapezia are well-documented defenders of their pocilloporid coral hosts against coral predators such as the Crown-of-Thorns seastar (Acanthaster planci complex). The objectives of this study were to examine the protective services of six species of Trapezia against corallivory, and the extent of functional diversity among these Trapezia species. Studies conducted in Mo’orea, French Polynesia showed the Trapezia—coral mutualism protected the host corals from mul...

  16. Excess Optical Enhancement Observed with ARCONS for Early Crab Giant Pulses

    OpenAIRE

    Strader, M. J.; Johnson, M. D.; Mazin, B. A.; Jaeger, G. V. Spiro; Gwinn, C. R.; Meeker, S. R.; Szypryt, P.; van Eyken, J. C.; Marsden, D.; O'Brien, K.; Walter, A. B.; Ulbricht, G.; Stoughton, C.; Bumble, B.

    2013-01-01

    We observe an extraordinary link in the Crab pulsar between the enhancement of an optical pulse and the timing of the corresponding giant radio pulse. At optical through infrared wavelengths, our observations use the high time resolution of ARray Camera for Optical to Near-IR Spectrophotometry, a unique superconducting energy-resolving photon-counting array at the Palomar 200 inch telescope. At radio wavelengths, we observe with the Robert C. Byrd Green Bank Telescope and the Green Bank Ultim...

  17. Dissolved oxygen content prediction in crab culture using a hybrid intelligent method

    OpenAIRE

    Yu, Huihui; Chen, Yingyi; Hassan, ShahbazGul; Li, Daoliang

    2016-01-01

    A precise predictive model is needed to obtain a clear understanding of the changing dissolved oxygen content in outdoor crab ponds, to assess how to reduce risk and to optimize water quality management. The uncertainties in the data from multiple sensors are a significant factor when building a dissolved oxygen content prediction model. To increase prediction accuracy, a new hybrid dissolved oxygen content forecasting model based on the radial basis function neural networks (RBFNN) data fusi...

  18. The Influence of Diet Composition on Fitness of the Blue Crab, Callinectes sapidus

    OpenAIRE

    Belgrad, Benjamin A.; Griffen, Blaine D.

    2016-01-01

    The physiological condition and fecundity of an organism is frequently controlled by diet. As changes in environmental conditions often cause organisms to alter their foraging behavior, a comprehensive understanding of how diet influences the fitness of an individual is central to predicting the effect of environmental change on population dynamics. We experimentally manipulated the diet of the economically and ecologically important blue crab, Callinectes sapidus, to approximate the effects ...

  19. Reaction of fungal products with amebocyte lysates of the Japanese horseshoe crab, Tachypleus tridentatus.

    OpenAIRE

    Hodes, D S; Heon, D; Hass, A; Hyatt, A C; Hodes, H L

    1987-01-01

    A commercially available endotoxin assay (CS-TAL) employing a chromogenic peptide and an amebocyte lysate from the Japanese horseshoe crab, Tachypleus tridentatus, gave a positive result with aqueous extracts of all 15 strains of Candida albicans and 1 strain each of Candida tropicalis, Cryptococcus neoformans, and a Mucor species that we tested. Purified glucans prepared from the Candida strains gave the same results. Reconstruction experiments showed that the positive results were not due t...

  20. A sensitive substrate for the clotting enzyme in horseshoe crab hemocytes.

    Science.gov (United States)

    Nakamura, S; Morita, T; Iwanaga, S; Niwa, M; Takahashi, K

    1977-05-01

    An endotoxin-activated hemocyte lysate from horseshoe crab (Tachypleus and Limulus) was found to hydrolyze specifically BZ-Ile-Glu-Gly-Arg-p-nitroanilide, which was recently introduced as the substrate for assay of the blood coagulation factor, Factor Xa. Further, this amidase activity increased by increasing the concentration of bacterial endotoxin (Salmonella minnesota R595) added to the lysate. Thus, the measurement of the amidase activity in the hemocyte lysate can be very useful to detect and determine the endotoxin.

  1. Etisus evamuellerae, a new xanthid crab (Decapoda, Brachyura) from the Middle Miocene of Austria and Hungary

    Science.gov (United States)

    Hyžný, M.; van Bakel, B.W.M.; Guinot, D.

    2015-01-01

    On the basis of several carapaces, a new species of xanthid crab, Etisus evamuellerae, is described from the Middle Miocene of the Vienna (Austria) and Great Hungarian basins. It differs from the coeval xanthids, Xantho moldavicus and Pilodius vulgaris, in having a distinctly protruding front and comparatively longer carapace. Contrary to those two species, the new one makes up for just a small percentage in the decapod crustacean assemblages studied. PMID:25983383

  2. HOM damping and multipacting analysis of the quarter-wave crab cavity

    International Nuclear Information System (INIS)

    Wu, Q.; Belomestnykh, S.; Ben-Zvi, I.; Calaga, R.

    2012-01-01

    The quarter-wave crab cavity design has been analyzed further to accommodate LHC requirements. The goal for the design is to provide strong deflecting voltage to the proton bunches at the IP, while keeping the effective length as short as possible. We will evaluate the higher order mode damping with two or four magnetic coupling dampers installed in different configuration. In this paper, we also show possible multipacting locations which are simulated by 2D and 3D codes.

  3. 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 processing waste so that it can optimalized any further.

  4. Designing the Four Rod Crab Cavity for the High-Luminosity LHC upgrade.

    CERN Document Server

    Hall, Ben

    2014-01-01

    This thesis presents the design for a novel compact crab cavity for the HL-LHC upgrade at CERN, Geneva. The LHC requires 400MHz RF cavities that can provide up to 10MV transverse gradient across two to three cavities with suit- ably low surface fields for continual operation. As a result, a cavity design was required that would be optimised to these new parameters. From initial design studies based on Jefferson Laboratory’s CEBAF deflector, extensive optimiza- tion was carried out to design a superconducting crab cavity, dubbed the Four Rod Crab Cavity (4RCC). The design underwent several iterations throughout the course of the project due to changing requirements from CERN, particularly space requirements inside the LHC. In addition, it was decided that a focus on field flatness was required. An aluminium prototype was then constructed from the finalised and computer-simulated design to confirm the designed field flat- ness. Additional computer simulation studies using CST were performed to en-...

  5. Serotonin induces ecdysteroidogenesis and methyl farnesoate synthesis in the mud crab, Scylla serrata.

    Science.gov (United States)

    Girish, B P; Swetha, C H; Reddy, P Sreenivasula

    2017-09-02

    In the current study, we have examined the role of serotonin in regulating the levels of methyl farnesoate and ecdysteroids in the giant mud crab Scylla serrata and validated that serotonin indeed is a reproductive hormone. Administration of serotonin elevated circulatory levels of methyl farnesoate and ecdysteroids in crabs. Since methyl farnesoate and ecdysteroid act through retinoid X receptor (RXR) and ecdysteroid receptor (EcR) respectively and these receptors are involved in the regulation of reproduction in crustaceans, we have determined the mRNA levels of RXR and EcR in hepatopancreas and ovary after serotonin administration. The expression levels of both RXR and EcR increased significantly in the hepatopancreas and ovary of serotonin injected crabs when compared to the controls. In vitro organ culture studies revealed that incubation of Y-orgas and mandibular organ explants in the presence of serotonin resulted in a significant increase in the secretion of ecdysteroids by Y-organs, but without alterations in MF synthesis in mandibular organs. From the above studies it is evident that serotonin stimulates Y organs resulting in increased ecdysteroidogenesis. Though the circulatory levels methyl farnesoate elevated after serotonin administration, organ culture studies revealed serotonin mediated methyl farnesaote synthesis is indirect probably by inhibiting release of mandibular organ inhibiting hormone from eyestalks. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Reproductive performance and larval quality of blue swimming crab (Portunus pelagicus broodstock, fed with different feeds

    Directory of Open Access Journals (Sweden)

    Vutthichai Oniam

    2012-09-01

    Full Text Available Fecundity, hatching rate and crab larvae quality of blue swimming crab, Portunus pelagicus, broodstock reared inearthen ponds, fed with different feeds, were studied for about 150 days. Results showed that average fecundity ofP. pelagicus broodstock fed with trash fish (569,842±243,173 eggs, shrimp feed (464,098±188,884 eggs, mixed feeds(544,875.3±169,357.3 eggs and hatching rate (50.78±25.19%, 62.33±26.79% and 50.86±20.76% were not significantly different(P>0.05. Zoea produced by female broodstock fed with mixed feeds had a significantly higher survival rate (89.47±5.03%,P<0.05 compared to those produced by female broodstock fed with trash fish (73.40±14.61% and shrimp feeds (67.33±12.80%, but the survival rate of megalopa and first crab stages was not affected. This study recommends that the mixed feedwas suitable feed for rearing of P. pelagicus broodstock in an earthen pond as evidenced by the quality of zoea I or 1 dayafter hatching and growth of female broodstock.

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

    Directory of Open Access Journals (Sweden)

    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. 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.

  9. Facultative parasitism by the bivalve Kurtiella pedroana in the sand crab Emerita analoga

    Science.gov (United States)

    Bhaduri, Ritin; Valentich-Scott, Paul; Hilgers, Mark; Singh, Rajvir; Hickman, Mikaila; Lafferty, Kevin D.

    2017-01-01

    It is rare that an organism capable of independent or commensalistic existence can also become endoparasitic on a host. In this study, we documented a potential step toward parasitism in the commensal clam Kurtiella pedroana (Bivalvia: Galeommatoidea). Galeommatoideans are known commensals of various invertebrates, including crustaceans. Emerita analoga (Decapoda: Hippidae) is an abundant intertidal decapod inhabiting sandy beaches of the Pacific coast of North and South America. Crabs collected from Monterey Bay, California, were measured and examined externally and internally for associated molluscs. Out of the 520 crabs, 37 large female individuals harbored 49 bivalves (prevalence of 7.11% and mean intensity of 1.3). Forty-one ectocommensal clams were either inside the crab's branchial chambers or on their lateroventral surfaces, and were attached by byssal threads. Our key finding was eight clams that lacked byssal threads and were living in the hemocoel. These internal clams were significantly smaller than the ectocommensals. Because these internal clams lacked access to their normal food, we hypothesize they might have fed on their host's hemolymph as would a parasite. This clam species likely can't reproduce inside its host, implying that endoparasitism is a dead-end state for K. pedroana. Facultative parasitism in a free-living or an ectocommensal is uncommon and suggests a pathway to parasitism.

  10. Pattern of shell utilization by the hermit crab Paguristes tortugae (Diogenidae from Anchieta Island, Southern Brazil

    Directory of Open Access Journals (Sweden)

    F. L.M. Mantelatto

    2002-09-01

    Full Text Available The objective of this study was to characterize the pattern of shell utilization by Paguristes tortugae, from infralittoral areas of Anchieta Island (Ubatuba, São Paulo State, Brazil using the percentage of the different shell types occupied and the morphometric relationship between hermit crabs and occupied shells. Specimens were collected monthly (January to December 1998 by SCUBA diving. The animals and the shells were measured and weighed. A total of 2,429 hermit crabs were captured occupying 21 species of gastropod shells. The shells more occupied were Pisania auritula (35.49%, Cerithium atratum (27.83%, Morula nodulosa (12.70% and Leucozonia nassa (6.83%, respectively. There was differential shell occupation between sexes: males and ovigerous females occupied in higher percentage P. auritula shells while the non-ovigerous females occupied C. atratum. Regression analysis showed best correlation between the size of the crabs (shield length and shell dry weight. This study showed that shell occupation by P. tortugae involves inter- and intraspecific competition as well as shell type availability in the field.

  11. Effects of Fiddler Crab Burrows on Sediment Properties in the Mangrove Mudflats of Sungai Sepang, Malaysia

    Directory of Open Access Journals (Sweden)

    Mohammad Mokhtari

    2016-01-01

    Full Text Available In mangrove ecosystems, litter fall accumulates as refractory organic carbon on the sediment surface and creates anoxic sediment layers. Fiddler crabs, through their burrowing activity, translocate oxygen into the anoxic layers and promote aerobic respiration, iron reduction and nitrification. In this study, the effects of four species of fiddler crabs (Uca triangularis, Uca rosea, Uca forcipata and Uca paradussumieri on organic content, water content, porosity, redox potential and solid phase iron pools of mangrove sediments were investigated. In each crab’s habitat, six cores down to 30 cm depth were taken from burrowed and non-burrowed sampling plots. Redox potential and oxidized iron pools were highest in surface sediment, while porosity, water and organic content were higher in deeper sediment. Reduced iron (Fe (II and redox potential were significantly different between burrowed and non-burrowed plots. Crab burrows extend the oxidized surface layer down to 4 cm depth and through the oxidation effect, reduce the organic content of sediments. The effects of burrows varied between the four species based on their shore location. The oxidation effect of burrows enhance the decomposition rate and stimulate iron reduction, which are processes that are expected to play an important role in biogeochemical properties of mangrove sediments.

  12. Trace fossil evidence of coral-inhabiting crabs (Cryptochiridae) and its implications for growth and paleobiogeography.

    Science.gov (United States)

    Klompmaker, Adiël A; Portell, Roger W; van der Meij, Sancia E T

    2016-03-24

    Members of the Cryptochiridae are small, fragile, symbiotic crabs that live in domiciles in modern corals. Despite their worldwide occurrence with over 50 species known today, their fossil record is unknown. We provide the first unambiguous evidence of cryptochirids in the fossil record through their crescentic pits, typical for certain cryptochirids, in Western Atlantic fossil corals, while the Eocene genus Montemagrechirus is excluded from the Cryptochiridae and referred to Montemagrechiridae fam. nov. Nine Pleistocene corals with crescentic pits originate from Florida (USA), and single specimens with pits come from the late Pleistocene of Cuba and the late Pliocene of Florida, all of which are measured for growth analyses. These pits represent trace fossils named Galacticus duerri igen. nov., isp. nov. A study of modern cryptochirid domicile shape (crescentic pit, circular-oval pit, or a true gall) shows that species within crab genera tend to inhabit the same pit shape. Crescentic pits in corals occur not only in the Western Atlantic today, but also in the Indo-West Pacific and in the Eastern Pacific. Thus, examination of Cenozoic fossil coral collections from these regions should yield further examples of cryptochirid pits, which would help to constrain the antiquity of this cryptic crab family.

  13. Biometry, histology, and morphometry of the digestive system of wild crab-eating fox (Cerdocyon thous

    Directory of Open Access Journals (Sweden)

    Andreíza Ramos Heleno

    2011-12-01

    Full Text Available The crab-eating fox (Cerdocyon thous is found throughout Brazil. It has a nocturnal habit and can be seen on roadsides, where it looks for remains of run over animals and, therefore, it is also a victim of roadkill. This study aimed to characterize the macro and microscopic anatomy of the digestive system of the crab-eating fox. It helps to carry out medical and surgical procedures, besides important information on the feeding strategies, especially for wild individuals needing veterinary care after rescue in cases of running over, burnings, and floods caused by the filling of hydroelectric reservoir lakes or even in projects on captive breeding and restocking. Samples were collected from the digestive system of three wild animals in the region of Guarapuava-PR region. The crab-eating foxes under study were longer than the average reported for the species, had a shorter intestine, and a lower small intestine/body length ratio than other carnivores, besides other anatomical and histological characteristics different from those found in the literature on carnivores.

  14. Chemical Tools of Octopus maya during Crab Predation Are Also Active on Conspecifics.

    Science.gov (United States)

    Pech-Puch, Dawrin; Cruz-López, Honorio; Canche-Ek, Cindy; Campos-Espinosa, Gabriela; García, Elpidio; Mascaro, Maite; Rosas, Carlos; Chávez-Velasco, Daniel; Rodríguez-Morales, Sergio

    2016-01-01

    Octopus maya is a major socio-economic resource from the Yucatán Peninsula in Mexico. In this study we report for the first time the chemical composition of the saliva of O. maya and its effect on natural prey, i.e. the blue crab (Callinectes sapidus), the crown conch snail (Melongena corona bispinosa), as well as conspecifics. Salivary posterior glands were collected from octopus caught by local fishers and extracted with water; this extract paralyzed and predigested crabs when it was injected into the third pereiopod. The water extract was fractionated by membrane ultrafiltration with a molecular weight cut-off of 3 kDa leading to a metabolic phase (>3 kDa) and a neurotoxic fraction (octopus saliva might be used among conspecifics for defense and for reduction of competition. Bioguided separation of the neurotoxic fraction by chromatography led to a paralysis fraction and a relaxing fraction. The paralyzing activity of the saliva was exerted by amino acids, while the relaxing activity was due to the presence of serotonin. Prey-handling studies revealed that O. maya punctures the eye or arthrodial membrane when predating blue crabs and uses the radula to bore through crown conch shells; these differing strategies may help O. maya to reduce the time needed to handle its prey.

  15. Crab shells as sustainable templates from nature for nanostructured battery electrodes.

    Science.gov (United States)

    Yao, Hongbin; Zheng, Guangyuan; Li, Weiyang; McDowell, Matthew T; Seh, Zhiwei; Liu, Nian; Lu, Zhenda; Cui, Yi

    2013-07-10

    Rational nanostructure design has been a promising route to address critical materials issues for enabling next-generation high capacity lithium ion batteries for portable electronics, vehicle electrification, and grid-scale storage. However, synthesis of functional nanostructures often involves expensive starting materials and elaborate processing, both of which present a challenge for successful implementation in low-cost applications. In seeking a sustainable and cost-effective route to prepare nanostructured battery electrode materials, we are inspired by the diversity of natural materials. Here, we show that crab shells with the unique Bouligand structure consisting of highly mineralized chitin-protein fibers can be used as biotemplates to fabricate hollow carbon nanofibers; these fibers can then be used to encapsulate sulfur and silicon to form cathodes and anodes for Li-ion batteries. The resulting nanostructured electrodes show high specific capacities (1230 mAh/g for sulfur and 3060 mAh/g for silicon) and excellent cycling performance (up to 200 cycles with 60% and 95% capacity retention, respectively). Since crab shells are readily available due to the 0.5 million tons produced annually as a byproduct of crab consumption, their use as a sustainable and low-cost nanotemplate represents an exciting direction for nanostructured battery materials.

  16. Fish Oil Microencapsulation as Omega-3 Fatty Acids Fortification Material for Cream of Crab Soup

    Directory of Open Access Journals (Sweden)

    Santiara Putri Pramesti

    2015-11-01

    Full Text Available Omega-3 fatty acids have important roles in improvement of intelligent and health of human. Microencapsulation of fish oil as source of omega-3 fatty acids is an effort to maintain flavor, aroma, stability, and also to successfully transfer bioactive component from the fish oil as fortification material for foods or medicines. Improvement of instant crab cream soup enriched with fish oil as source of omega-3 fatty acid has never been conducted before. The purpose of this research was to improve microencapsulation method for fish oil as source of omega-3 fatty acids as fortification material for instant cream of crab soup. Microencapsulation methods in this research are homogenization and spray drying. The results showed that the best microcapsule was obtained from homogenization treatment for 10 minutes with efficiency of 90.41±0.64%. The shape of the obtained microcapsule was spherical with average size of 6.52 μm, with induction time up to 26.09±0.01 hours. The best cream of crab soup formula was at fish oil microcapsule concentration of 3.30%, with 8.19% daily value of omega-3, inclusion 11.32% of EPA and DHA at serving size of 17.56 gram.

  17. Camouflage and individual variation in shore crabs (Carcinus maenas from different habitats.

    Directory of Open Access Journals (Sweden)

    Martin Stevens

    Full Text Available Camouflage is widespread throughout the natural world and conceals animals from predators in a vast range of habitats. Because successful camouflage usually involves matching aspects of the background environment, species and populations should evolve appearances tuned to their local habitat, termed phenotype-environment associations. However, although this has been studied in various species, little work has objectively quantified the appearances of camouflaged animals from different habitats, or related this to factors such as ontogeny and individual variation. Here, we tested for phenotype-environment associations in the common shore crab (Carcinus maenas, a species highly variable in appearance and found in a wide range of habitats. We used field surveys and digital image analysis of the colors and patterns of crabs found in four locations around Cornwall in the UK to quantify how individuals vary with habitat (predominantly rockpool, mussel bed, and mudflat. We find that individuals from sites comprising different backgrounds show substantial differences in several aspects of color and pattern, and that this is also dependent on life stage (adult or juvenile. Furthermore, the level of individual variation is dependent on site and life stage, with juvenile crabs often more variable than adults, and individuals from more homogenous habitats less diverse. Ours is the most comprehensive study to date exploring phenotype-environment associations for camouflage and individual variation in a species, and we discuss the implications of our results in terms of the mechanisms and selection pressures that may drive this.

  18. A Comparative Study of the Uptake, Clearance and Metabolism of Technetium in Lobster (Homarus Gammarus) and Edible Crab (Cancer Paguras)

    Energy Technology Data Exchange (ETDEWEB)

    Knowles, J.F.; Smith, D.L.; Winpenny, K

    1998-07-01

    Lobsters and edible crabs have been exposed to {sup 95}Tc{sup m} in their sea water or in their food, and the uptake, retention and distribution of the isotope in their bodies examined. The steady-state concentration factor C{sub ss} for uptake of {sup 95}Tc{sup m} from sea water was significantly greater for female crabs (C{sub ss}=17.9) than for males (C{sub ss}=14.4). There was no such sex difference in lobsters and they took up {sup 95}Tc{sup m} to much higher levels with a C{sub ss} of 1160. Retention of the isotope was similar for crabs and lobsters and for animals of both sexes. However the route of uptake was important with more rapid clearance after uptake from sea water (t{sub b1/2} = 51 days) than after uptake from food (t{sub b1/2} = 108 days). Technetium was found predominantly in the hepatopancreas of all crabs and most male lobsters. In a few male lobsters and all females it was mainly in muscle. Lobster ovaries consistently contained more activity than testes but this difference was not seen in crabs. At the subcellular level {sup 95}Tc{sup m} in hepatopancreas cells of both lobster and crab occurred mainly in the cytosol. Results of initial studies into the relationships between technetium and cytosol proteins are given and the possible basis for the much greater accumulation of the element by lobsters than crabs discussed. (author)

  19. 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.

  20. Abundance of non-native crabs in intertidal habitats of New England with natural and artificial structure

    Directory of Open Access Journals (Sweden)

    Christina M. Lovely

    2015-09-01

    Full Text Available Marine habitats containing complex physical structure (e.g., crevices can provide shelter from predation for benthic invertebrates. To examine effects of natural and artificial structure on the abundance of intertidal juvenile crabs, 2 experiments were conducted in Kingston Bay, Massachusetts, USA, from July to September, 2012. In the first experiment, structure was manipulated in a two-factor design that was placed in the high intertidal for 3 one-week periods to test for both substrate type (sand vs. rock and the presence or absence of artificial structure (mesh grow-out bags used in aquaculture, ∼0.5 m2 with 62 mm2 mesh openings. The Asian shore crab, Hemigrapsus sanguineus, and small individuals of the green crab, Carcinus maenas, were observed only in the treatments of rocks and mesh bag plus rocks. Most green crabs were small (<6 mm in carapace width whereas H. sanguineus occurred in a wide range of sizes. In the second experiment, 3 levels of oyster-shell treatments were established using grow-out bags placed on a muddy sand substrate in the low intertidal zone: mesh grow-out bags without shells, grow-out bags with oyster shells, and grow-out bags containing live oysters. Replicate bags were deployed weekly for 7 weeks in a randomized complete block design. All crabs collected in the bags were juvenile C. maenas (1–15 mm carapace width, and numbers of crabs differed 6-fold among treatments, with most crabs present in bags with live oysters (29.5 ± 10.6 m−2 [mean ± S.D.] and fewest in bags without shells (4.9 ± 3.7 m−2. Both C. maenas and H. sanguineus occurred in habitats with natural structure (cobble rocks. The attraction of juvenile C. maenas to artificial structure consisting of plastic mesh bags containing both oyster shells and living oysters could potentially impact oyster aquaculture operations.

  1. Ecological Assessment of Two Species of Potamonautid Freshwater Crabs from the Eastern Highlands of Zimbabwe, with Implications for Their Conservation.

    Directory of Open Access Journals (Sweden)

    Tatenda Dalu

    Full Text Available The spatial ecology of freshwater crabs and their conservation status is largely understudied in Africa. An ecological assessment was conducted at 104 localities in 51 rivers and/or streams in the Eastern Highlands of Zimbabwe whereby the distribution and abundances of freshwater crab species were mapped and the possible drivers of the observed trends in population structure explored. In addition, information on crab utilisation as a food resource by local communities was assessed via face to face interviews across the region. Finally, the conservation status of each species was assessed using the IUCN Red List criteria. Only two crab species Potamonautes mutareensis and Potamonautes unispinus were recorded within the region of study. Potamonautes mutareensis was largely restricted to less impacted environments in the high mountainous river system, whereas P. unispinus was found in low laying areas. In stretches of river where both species were found to co-occur, the species were never sampled from the same site, with P. mutareensis occurring in shallower, faster flowing environments and P. unispinus in deeper, slow flowing sites. Interview results revealed that the local communities, particularly in the southern part of the Eastern Highlands around the Chipinge area, had a considerable level of utilisation (55% of households on the harvesting of crabs for household consumption during the non-agricultural season (May to September. Results from the IUCN Red List assessment indicate that both species should be considered as "Least Concern". Threats to freshwater crabs in the Eastern Highlands, however, include widespread anthropogenic impacts such as habitat destruction associated with gold and diamond mining, inorganic and organic pollution and possibly exploitation for human consumption. The current study provides important information and insight towards the possible development of a freshwater crab conservation action plan within the region.

  2. Locomotor behavior of nocturnal ghost crabs on the beach: focal animal sampling and instantaneous velocity from three-dimensional motion analysis.

    Science.gov (United States)

    Weinstein, R B

    1995-04-01

    Previous laboratory measurements of the energetics and biomechanics of locomotion have defined performance limits for the ghost crab Ocypode quadrata. To discover whether these animals naturally operate within these limits, a novel infrared videotaping system was used to observe nocturnally active ghost crabs in the field for three-dimensional motion analysis (N = 27) and focal animal sampling (N = 24). Instantaneous movement velocity, movement duration, pause duration and stride frequency were determined from video tapes. Voluntarily active crabs moved at a mean instantaneous velocity of 8 cm s-1. Stressed crabs (i.e. those captured and released into the field site) moved at a mean velocity of 83 cm s-1. The mean movement and pause period durations of voluntarily active animals moving along the beach were 11.2 and 23.4 s, respectively. Stressed crabs had much shorter movement (1.4 s) and pause (7.6 s) durations. Despite the differences in mean movement and pause duration, both voluntarily active and stressed crabs moved for an average of approximately 30% of the observation period. These data indicate that voluntarily active ghost crabs primarily move at velocities that can be sustained aerobically and that their performance is not likely to be altered by moving intermittently. By contrast, stressed crabs move at faster speeds that are closer to the limits of their continuous locomotor performance (e.g. escape behavior and aggressive encounters). In the laboratory, the endurance capacity of crabs moving continuously at these rapid speeds is only a few seconds. However, in the field, the stressed crabs are able to move intermittently for more than a few seconds, yet they do not fatigue. These observations suggest that the performance limits of the stressed crabs are increased by moving intermittently.

  3. Characterization of copper transport in gill cells of a mangrove crab Ucides cordatus

    Energy Technology Data Exchange (ETDEWEB)

    Sá, M.G. [Biosciences Institute, Department of Physiology, University of São Paulo, Rua do Matão, Travessa 14, 101, São Paulo 05508-900, SP (Brazil); Zanotto, F.P., E-mail: fzanotto@usp.br [Biosciences Institute, Department of Physiology, University of São Paulo, Rua do Matão, Travessa 14, 101, São Paulo 05508-900, SP (Brazil); Department of Biophysics, Escola Paulista de Medicina, Universidade Federal de Sao Paulo, Rua Três de Maio 100, Sao Paulo 04044-020 (Brazil)

    2013-11-15

    Highlights: •Copper transport in gill cells of a mangrove crab Ucides cordatus is dependent of calcium. •Copper transport mechanism is ATP-dependent. •Transport was monitored second by second during 300 s. -- Abstract: The branchial epithelium of crustaceans is exposed to the environment and is the first site affected by metal pollution. The aim of this work was to characterize copper (Cu) transport using a fluorescent dye, Phen Green, in gill cells of a hypo-hyper-regulator mangrove crab Ucides cordatus. The results showed that added extracellular CuCl{sub 2} (0, 0.025, 0.150, 0.275, 0.550 and 1.110 μM) showed typical Michaelis–Menten transport for Cu in anterior and posterior gill cells (V{sub max} for anterior and posterior gills: 0.41 ± 0.12 and 1.76 ± 0.27 intracellular Cu in μM × 22.10{sup 4} cells{sup −1} × 300 s{sup −1} respectively and K{sub m} values: 0.44 ± 0.04 and 0.32 ± 0.13 μM, respectively). Intracellular Cu was significantly higher for posterior gill cells compared to anterior gill cells, suggesting differential accumulation for each gill type. Extracellular Ca at 20 mM decreased cellular Cu transport for both anterior and posterior gill cells. Nifedipine and verapamil, calcium channel inhibitors from plasma membrane, decreased Cu transport and affected K{sub m} for both gills. These results could be due to a competition between Cu and Ca. Amiloride, a Na/Ca exchanger inhibitor, as well as bafilomycin, a proton pump inhibitor, caused a decrease of intracellular Cu compared to control. Ouabain and KB-R 7943, acting on Na homeostasis, similarly decreased intracellular Cu in both gill cells. Besides that, gill cells exposed to ATP and Cu simultaneously, showed an increase in intracellular copper, which was inhibited by vanadate, an inhibitor of P-type ATPase. These results suggest either the presence of a Cu-ATPase in crab gill cells, responsible for Cu influx, or the effect of a change in electrochemical membrane potential that

  4. Preliminary Assessment of Potential Impacts to Dungeness Crabs from Disposal of Dredged Materials from the Columbia River

    Energy Technology Data Exchange (ETDEWEB)

    Pearson, Walter H.; Miller, Martin C.; Williams, Greg D.; Kohn, Nancy P.; Skalski, John R.

    2006-02-01

    Dredging of the Columbia River navigation channel has raised concerns about dredging-related impacts on Dungeness crabs (Cancer magister). The overall objectives of this effort are to synthesize what is known about disposal effects on Dungeness crabs (Phase 1) and to offer approaches to quantify the effects, including approaches to gain a population-level perspective on any effects found in subsequent studies (Phase 2). This report documents Phase 1, which included (1) development of a conceptual model to integrate knowledge about crab biology and the physical processes occurring during disposal, (2) application of physics-based numerical modeling of the disposal event to understand the physical forces and processes to which a crab might be exposed during disposal, (3) conduct of a vulnerability analysis to identify the potential mechanisms by which crabs may be injured, and (4) recommendations of topics and approaches for future studies to assess the potential population-level effects of disposal on Dungeness crabs. The conceptual model first recognizes that disposal of dredged materials is a physically dynamic process with three aspects: (1) convective descent and bottom encounter, (2) dynamic collapse and spreading, and (3) mounding. Numerical modeling was used to assess the magnitude of the potentially relevant forces and extent of mounding in single disposal events. The modeling outcomes show that predicted impact pressure, shear stress, and mound depth are greatly reduced by discharge in deep water, and somewhat reduced at longer discharge duration. The analysis of numerical modeling results and vulnerabilities indicate that the vulnerability of crabs to compression forces under any of the disposal scenarios is low. For the deep-water disposal scenarios, the maximum forces and mounding do not appear to be sufficiently high enough to warrant concern for surge currents or burial at the depths involved (over 230 ft). For the shallow-water (45 to 65 ft), short

  5. Histopathological effects of chlorpyrifos on the gills, hepatopancreas and gonads of the freshwater crab Zilchiopsis collastinensis. Persistent effects after exposure.

    Science.gov (United States)

    Negro, C L; Collins, P

    2017-06-01

    Sublethal effects of the pesticide chlorpyrifos were evaluated in the crab Zilchiopsis collastinensis (Decapoda, Trichodactylidae). Crabs were exposed to high concentrations of chlorpyrifos at the beginning of the experiment and controlled dilution, under natural light and temperature conditions. A control and three concentrations (22.4, 41.25 and 61.4µg chlorpyrifos L -1 ) were evaluated in triplicate. Nine crabs per concentration and day were used. The gills, hepatopancreas and ovaries were sampled before pesticide exposure (day 0) and 8, 15 and 22 days later, when concentrations were diluted and below the detection limits. The histopathological effects and their variations in time were observed and quantified. In gills, hyperplasias were observed in several cases, mainly in crabs exposed to chlorpyrifos. The number of collapsed lamellae and the number of affected lamellae quickly increased in exposed crabs, as effects were observed on day 8 and remained until day 22. In hepatopancreas there was an increase in the number of F and B -cells and affected tubules, especially after 22 days of exposure (peffects on gonadosomatic indexes or oocyte volume, but there was a significant increase in the atretic oocyte proportion related to pesticide exposure (peffects on the gills, hepatopancreas and ovaries were observed after exposure and persist even after dilution, and might be related to earlier exposures. Thus, these histopathological effects might be used as pesticide biomarkers even after the pesticide is not detected by chemical methods. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. 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

    2018-02-20

    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 filters that allowed for variable UV penetration. Solar exposures (duration: 7-h per day) were conducted for two consecutive days, with a 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.

  7. Living with a crab: effect of Austinotheres angelicus (Brachyura, Pinnotheridae infestation on the condition of Saccostrea palmula (Ostreoida, Ostreidae

    Directory of Open Access Journals (Sweden)

    Sebastián Mena

    Full Text Available Some members of the Pinnotheridae family exhibit close symbiotic relationships with bivalves, which may cause severe damage to the mollusk. The condition index (CI is a tool that serves to evaluate the effect of biotic and abiotic factors on the morphology and physiology of mollusks, including those caused by symbiotic organisms. In the present study, we evaluated the effects of the infestation of the pinnotherid crab Austinotheres angelicus on the oyster Saccostrea palmula through monthly sampling (April to November 2012 in Punta Morales, Pacific coast of Costa Rica. A total of 245 oysters were analyzed, of which 38% were infested by the pinnotherid crab. Most of the oysters analyzed (92% varied in depth between 1.5 and 15.0 mm; 89% of the infested oysters were in this depth range. The prevalence was positively correlated with the depth of the oyster. Our results revealed that crab infestation could reduce the CI by 11 to 33%. The obtained findings suggest that the infestation by A. angelicus provokes alterations of the flesh production of the oyster, especially when the association is with a pair of crabs including an ovigerous female. The association of A. angelicus with S. palmula is best described as facultative parasitism for male crabs and obligatory parasitism for females.

  8. Tissue distribution, subcellular localization and endocrine disruption patterns induced by Cr and Mn in the crab Ucides cordatus

    International Nuclear Information System (INIS)

    Correa, Jose Dias; Ramos da Silva, Miguel; Bastos da Silva, Antonio Carlos; Araujo de Lima, Silene Maria; Malm, Olaf; Allodi, Silvana

    2005-01-01

    The essential trace elements Cr and Mn are toxic at high concentrations and information about low concentration is insufficient in the literature. In polluted mangroves, the crab Ucides cordatus can represent a useful tool to assess information on the potential impact of trace elements like Cr and Mn on the environment, since this species is comestible and thus, commercially negotiated. Therefore, U. cordatus crabs were exposed in vivo to different concentrations of Cr and Mn solved in seawater and had their tissue distribution and subcellular deposits evaluated. The gill, hepatopancreas and muscle concentrations were determined by atomic absorption spectroscopy and the results showed that Cr and Mn presented the highest values in the gills rather than in the hepatopancreas and muscular tissue. Electron microscopy and analytical X-ray microanalysis revealed Cr precipitates on the gill surface, co-localized with epiphyte bacteria. In addition, since Cr and Mn did not equally accumulate in most of the tissues studied, glycemic rate of animals, which received injections of extracts of eyestalks of the contaminated crabs, were measured in order to evaluate whether the studied concentrations of Cr and Mn could produce any metabolic alteration. The results indicated that extracts of the eyestalks of crabs submitted to Cr and Mn salts and injected into normal crabs markedly influenced crustacean hyperglycemic hormone synthesis and/or release. The results are discussed with respect to sensitivity of the employed methods and the possible significance of the concentrations of Cr and Mn in the organisms

  9. High resolution tracking of adult horseshoe crabs Limulus polyphemus in a New Hampshire estuary using fixed array ultrasonic telemetry

    Directory of Open Access Journals (Sweden)

    Winsor H. WATSON III, Christopher C. CHABOT

    2010-10-01

    Full Text Available While several studies have documented the large-scale, seasonal movements of horseshoe crabs, little is known about their fine-scale, daily movement patterns. In this study we used a fixed array ultrasonic telemetry system to track the movements of 12 male and 16 female horseshoe crabs in the Great Bay estuary, New Hampshire. Data were obtained during the mating season, as well as during the remainder of the summer and fall, in the years 2005-2008. During the mating season animals were often, but not always, active during the high tides when they were approaching and leaving the spawning beaches. On average, both males and females approached mating beaches during 33% of the high tides they experienced and they most often made the transition from being inactive to active during the last two hours of an incoming tide. From April-October horseshoe crabs were significantly more active during high tide periods vs low tide periods, with no clear preference for diurnal vs nocturnal activity. After the mating season ended horseshoe crabs continued to move into shallower water at high tide and then return to deeper water at low tide. Observations by SCUBA divers suggest that during these excursions into the mudflats horseshoe crabs were digging pits in the sediment while foraging for food. Thus, the tidal rhythm of activity that has been so well documented during the mating season probably persists into the fall, and primarily involves foraging activities [Current Zoology 56 (5: 599–610, 2010].

  10. Assessment and Mmanagement of North American horseshoe crab populations, with emphasis on a multispecies framework for Delaware Bay, U.S.A. populations: Chapter 24

    Science.gov (United States)

    Millard, Michael J.; Sweka, John A.; McGowan, Conor P.; Smith, David R.

    2015-01-01

    The horseshoe crab fishery on the US Atlantic coast represents a compelling fishery management story for many reasons, including ecological complexity, health and human safety ramifications, and socio-economic conflicts. Knowledge of stock status and assessment and monitoring capabilities for the species have increased greatly in the last 15 years and permitted managers to make more informed harvest recommendations. Incorporating the bioenergetics needs of migratory shorebirds, which feed on horseshoe crab eggs, into the management framework for horseshoe crabs was identified as a goal, particularly in the Delaware Bay region where the birds and horseshoe crabs exhibit an important ecological interaction. In response, significant effort was invested in studying the population dynamics, migration ecology, and the ecologic relationship of a key migratory shorebird, the Red Knot, to horseshoe crabs. A suite of models was developed that linked Red Knot populations to horseshoe crab populations through a mass gain function where female spawning crab abundance determined what proportion of the migrating Red Knot population reached a critical body mass threshold. These models were incorporated in an adaptive management framework wherein optimal harvest decisions for horseshoe crab are recommended based on several resource-based and value-based variables and thresholds. The current adaptive framework represents a true multispecies management effort where additional data over time are employed to improve the predictive models and reduce parametric uncertainty. The possibility of increasing phenologic asynchrony between the two taxa in response to climate change presents a potential challenge to their ecologic interaction in Delaware Bay.

  11. 50 CFR Table 41 to Part 679 - BSAI Crab PSC Sideboard Limits for AFA Catcher/Processors and AFA Catcher Vessels

    Science.gov (United States)

    2010-10-01

    ... Catcher/Processors and AFA Catcher Vessels 41 Table 41 to Part 679 Wildlife and Fisheries FISHERY... Sideboard Limits for AFA Catcher/Processors and AFA Catcher Vessels For the following crab species in the following areas . . . The AFA catcher/processor crab PSC sideboard limit is equal to the followingratio...

  12. BIOGEOGRAPHIC DISTRIBUTIONS, ABUNDANCES, AND VULNERABILITIES TO CLIMATE CHANGE OF BRACHYURAN AND LITHODID CRABS FROM THE GULF OF CALIFORNIA TO THE BEAUFORT SEA - 9-19-2014

    Science.gov (United States)

    As part of an EPA/USGS project 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...

  13. 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)

    As part of an EPA/USGS project 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...

  14. On the ecology of Coenobita clypeatus in Curaçao with reference to reproduction, water economy and osmoregulation in terrestrial hermit crabs

    NARCIS (Netherlands)

    Wilde, de P.A.W.J.

    1973-01-01

    1. This paper deals with various aspects of the life-history, ecology, water management and osmoregulation of the West-Indian land hermit crab Coenobita clypeatus (Herbst) in Curaçao, Netherlands Antilles. 2. Land hermit crabs belonging to the family Coenobitidae may be considered as one of the most

  15. Short-term exposure to benzo[a]pyrene causes oxidative damage and affects haemolymph steroid levels in female crab Portunus trituberculatus

    International Nuclear Information System (INIS)

    Wen, Jianmin; Pan, Luqing

    2016-01-01

    Concern has increased regarding the adverse effects of polycyclic aromatic hydrocarbons (PAHs) on reproduction. However, limited information is available on the effects of PAHs in crustacean. In order to determine whether benzo[a]pyrene (B[a]P) could cause reproductive toxicity on the swimming crab Portunus trituberculatus, sexually mature female crabs were exposed to environmentally relevant concentrations of B[a]P (0, 0.1, 0.5 and 2.5 μg/L) for 10 days. B[a]P treatments resulted in high accumulation in ovary, and induced oxidative stress in a dose-dependent manner on ovary of crab. Furthermore, the haemolymph estradiol (E 2 ) and testosterone (T) levels were significantly decreased. Histological investigation also revealed the reproductive toxicity caused by B[a]P. The results demonstrated that waterborne exposure to B[a]P caused oxidative damage and disrupted sex steroids in female crab P. trituberculatus, ultimately resulting in histological alternation. - Highlights: • Waterborne exposure to B[a]P resulted in high accumulation in crab ovary. • The haemolymph 17β-estradiol and testosterone levels were significantly decreased by B[a]P exposure. • B[a]P induced oxidative damage in crab ovary. • B[a]P exposure caused histopathological alterations in crab ovary. - B[a]P disrupted sex steroids, caused oxidative damage and histological alternation in female crab P. trituberculatus.

  16. A group-specific, quantitative real-time PCR assay for detection of crab, a crustacean shellfish allergen, in complex food matrices.

    Science.gov (United States)

    Eischeid, Anne C; Stadig, Sarah R

    2018-04-01

    A real-time PCR assay was developed for detection of crab, a crustacean allergen, in food products. Group-specific primers and probes were developed to detect numerous species of crab. Method validation included tests of detection in complex food matrices, evaluation of commercial food products, and cross-reactivity testing on a wide variety of crustaceans. The method was able to detect several species of crab spiked into complex food matrices at levels ranging from 0.1 to 10 5 parts per million (weight/weight), worked equally well on different platforms, exhibited high specificity for crab over other types of crustaceans, and yielded much higher signals from commercial food products listing crab as an ingredient than from those containing other crustaceans. Published by Elsevier Ltd.

  17. Specific primers for the detection of the black-yeast fungus associated with lethargic crab disease (LCD).

    Science.gov (United States)

    Pie, Marcio R; Boeger, Walter A; Patella, Luciana; Vicente, Vânia A; Ribeiro, Raphael O; Ostrensky, Antonio

    2011-03-16

    Lethargic crab disease (LCD) is an emerging infirmity that has been causing extensive mortalities in populations of the mangrove land crab Ucides cordatus (Ocypodidae) along the Atlantic coast of Brazil. Previous studies have indicated that LCD is associated with a dematiaceous fungus, Exophiala cancerae de Hoog et al. In the present study, we sequenced the internal transcribed spacer (ITS) of the rDNA region of this black yeast species and developed species-specific PCR primers. Sensitivity tests indicated that the developed protocol is capable of detecting very small amounts of target DNA. Also, the application of the protocol to a variety of other dematiaceous fungi did not generate any false positives. The specific primers provided in the present study represent an important tool for rapidly surveying a large number of crab individuals, as well as environmental samples. Such knowledge will be instrumental in understanding the epidemiological dynamics of LCD.

  18. An antifungal chitinase produced by Bacillus cereus with shrimp and crab shell powder as a carbon source.

    Science.gov (United States)

    Chang, Wen-Teish; Chen, Chin-Shuh; Wang, San-Lang

    2003-08-01

    The production of inexpensive chitinolytic enzymes is an element in the utilization of shellfish processing wastes. In this study, shrimp and crab shell powder prepared by treating shrimp and crab processing wastes with boiling and crushing was used as a substrate for the isolation of an antifungal chitinase-producing microorganism. Bacillus cereus YQ 308, a strain isolated from the soil samples, excreted one chitinase when cultured in a medium containing 2% (wt/vol) shrimp and crab shell powder as major carbon source. The chitinase, purified by sequential chromatography, had an Mr of 48 kDa and pI of 5.2. The purified chitinase (2 mg/ml) inhibited the hyphal extension of the fungi Fusarium oxysporum and Pythium ultimum.

  19. Laboratory Assessment of Potential Impacts to Dungeness Crabs from Disposal of Dredged Material from the Columbia River

    Energy Technology Data Exchange (ETDEWEB)

    Vavrinec, John; Pearson, Walter H.; Kohn, Nancy P.; Skalski, J. R.; Lee, Cheegwan; Hall, Kathleen D.; Romano, Brett A.; Miller, Martin C.; Khangaonkar, Tarang P.

    2007-05-07

    Dredging of the Columbia River navigation channel has raised concerns about dredging-related impacts on Dungeness crabs (Cancer magister) in the estuary, mouth of the estuary, and nearshore ocean areas adjacent to the Columbia River. The Portland District, U.S. Army Corps of Engineers engaged the Marine Sciences Laboratory (MSL) of the U.S. Department of Energy’s Pacific Northwest National Laboratory to review the state of knowledge and conduct studies concerning impacts on Dungeness crabs resulting from disposal during the Columbia River Channel Improvement Project and annual maintenance dredging in the mouth of the Columbia River. The present study concerns potential effects on Dungeness crabs from dredged material disposal specific to the mouth of the Columbia River.

  20. Infestation and morphological identification of the stalked epizoic barnacle Octolasmis on the blue crab Portunus pelagicus from the Red Sea

    Science.gov (United States)

    Afifi Khattab, Rafat

    2017-09-01

    The intensity of infestation of the epizoic stalked barnacle Octolasmis on the blue crab was calculated for a total of 180 individuals collected around Jeddah, the western Red Sea Saudi coast. More than 90% of the crabs were found bearing the Octolasmis at a prevalence rate of 92% and mean intensity of 18.5±18.6 (0-127 epibiont per host). The intensity of infestation increased with host size in the range 90-135 mm. Generally, females were more infested (69%) than the males (31%). Octolasmis angulata occurred mostly on the gills, and the lower side of the gill chambers was more infested (84%) than the upper side (16%) and the left side of gills was also more infested than the right side in both males and females. Further studies are still needed to examine the commensal relationship and its impact on the fishery market of the Red Sea blue crab populations.

  1. Determination of key environmental factors responsible for distribution patterns of fiddler crabs in a tropical mangrove ecosystem.

    Directory of Open Access Journals (Sweden)

    Mohammad Mokhtari

    Full Text Available In tropical regions, different species of fiddler crabs coexist on the mangrove floor, which sometimes makes it difficult to define species-specific habitat by visual inspection. The aim of this study is to find key environmental parameters which affect the distribution of fiddler crabs and to determine the habitats in which each species was most abundant. Crabs were collected from 19 sites within the mudflats of Sepang-Lukut mangrove forest. Temperature, porewater salinity, organic matter, water content, carbon and nitrogen content, porosity, chlorophyll content, pH, redox potential, sediment texture and heavy metals were determined in each 1 m2 quadrate. Pearson correlation indicated that all sediment properties except pH and redox potential were correlated with sediment grain size. Canonical correspondence analysis (CCA indicated that Uca paradussumieri was negatively correlated with salinity and redox potential. Sand dwelling species, Uca perplexa and Uca annulipes, were highly dependent on the abundance of 250 μm and 150 μm grain size particles in the sediment. Canonical Discriminative Analysis (CDA indicated that variation in sediment grain size best explained where each crab species was most abundant. Moreover, U. paradussumieri commonly occupies muddy substrates of low shore, while U. forcipata lives under the shade of mangrove trees. U. annulipes and U. perplexa with the high number of spoon tipped setae on their second maxiliped are specialized to feed on the sandy sediments. U. rosea and U. triangularis are more common on muddy sediment with high sediment density. In conclusion, sediment grain size that influences most sediment properties acts as a main factor responsible for sediment heterogeneity. In this paper, the correlation between fiddler crab species and environmental parameters, as well as the interaction between sediment characteristics, was explained in order to define the important environmental factors in fiddler crab

  2. Effects of domestic effluent discharges on mangrove crab physiology: Integrated energetic, osmoregulatory and redox balances of a key engineer species.

    Science.gov (United States)

    Theuerkauff, Dimitri; Rivera-Ingraham, Georgina A; Mercky, Yann; Lejeune, Mathilde; Lignot, Jehan-Hervé; Sucré, Elliott

    2018-03-01

    Mangroves are increasingly used as biofiltering systems of (pre-treated) domestic effluents. However, these wastewater discharges may affect local macrofauna. This laboratory study investigates the effects of wastewater exposure on the mangrove spider crab Neosarmatium meinerti, a key engineering species which is known to be affected by waste waters in effluent-impacted areas. These effects were quantified by monitoring biological markers of physiological state, namely oxygen consumption, the branchial cavity ventilation rate, gill physiology and morphology, and osmoregulatory and redox balance. Adults acclimated to clean seawater (SW, 32 ppt) and freshwater (FW, ∼0 ppt) were compared to crabs exposed to wastewater for 5 h (WW, ∼0 ppt). Spider crabs exposed to WW increased their ventilation and whole-animal respiration rates by 2- and 3-fold respectively, while isolated gill respiration increased in the animals exposed to FW (from 0.5 to 2.3 and 1.1 nmol O 2 min -1  mg DW -1 for anterior and posterior gills, respectively) but was not modified in WW-exposed individuals. WW exposure also impaired crab osmoregulatory capacity; an 80 mOsm kg -1 decrease was observed compared to FW, likely due to decreased branchial NKA activity. ROS production (DCF fluorescence in hemolymph), antioxidant defenses (superoxide dismutase and catalase activities) and oxidative damage (malondialdehyde concentration) responses varied according to animal gender. Overall, this study demonstrates that specific physiological parameters must be considered when focusing on crabs with bimodal breathing capacities. We conclude that spider crabs exposed to WW face osmoregulatory imbalances due to functional and morphological gill remodeling, which must rapidly exhaust energy reserves. These physiological disruptions could explain the ecological changes observed in the field. Copyright © 2018. Published by Elsevier B.V.

  3. [Two new species of freshwater crabs (Decapoda: Potamidae) serving as intermediate hosts of Paragonimus in Fujian, China].

    Science.gov (United States)

    Cheng, You-zhu; Lin, Guo-hua; Li, You-song

    2010-08-01

    To investigate the natural resources of the freshwater crab which can serve as the intermediate hosts of Paragonimus in Pinghe and Youxi of Fujian Province. Freshwater crabs were collected. The morphological characteristics of the crabs and the habitats were observed. The crabs were dissected and examined for the presence of Paragonimus metacercariae. Two new species of crabs were described, named as Sinopotamon zhangzhouense sp. nov. and Bottapotamon youxiense sp. nov.. S. zhangzhouense sp. nov., holotype: male, carapace length 35.9 mm, breadth 42.8 mm, thickness 18.6 mm, collected from Pinghe County in southwest of Fujian. (24 degrees 14.206' N, 117 degrees 12.594' E). Distal segment of the first pleopod of male tended flattish, and showed palm nest-shaped concave, which divided into two point leafs, and longitudinal crack clearly identified in back. The end half of distal segment reversed to ventral outwardly. This species usually lived in the sluggish stream. The infection rate of Paragonimus westermani and P. cenocopiosus in S. zhangzhouense sp. nov. was 44.9% (35/78). B. youxiense sp. nov., holotype: male, carapace length 13.35 mm, breadth 16.63 mm, thickness 7.20 mm, collected from Youxi County in central Fujian (26 degrees 10.558' N, 118 degrees 22.012' E). The first pleopod of male was in slightly flat shape, ample and developed, as bow-like uplift. This species usually lived in the relatively flat terrain of stream. The infection rate of P. skrjabini metacercariae in B. youxiense sp. nov. was 92.1% (58/63). Two new species of freshwater crabs (S. zhangzhouense sp nov. and Ryouxiense sp. nov.) serving as the intermediate hosts of Paragonimus have been described.

  4. BIOCHEMICAL AND ULTRASTRUCTURAL ASPECTS OF CA2+ TRANSPORT BY MITOCHONDRIA OF THE HEPATOPANCREAS OF THE BLUE CRAB CALLINECTES SAPIDUS

    Science.gov (United States)

    Chen, Chung-Ho; Greenawalt, John W.; Lehninger, Albert L.

    1974-01-01

    Mitochondria isolated from the hepatopancreas of the blue crab Callinectes sapidus show up to 12-fold stimulation of respiration on addition of Ca2+, which is accompanied by Ca2+ accumulation (Ca2+:site = 1.9) and H+ ejection (H+:Ca2+ = 0.85). Sr2+ and Mn2+ are also accumulated; Mg2+ is not. A strongly hypertonic medium (383 mosM), Mg2+, and phosphate are required for maximal Ca2+ uptake. Ca2+ uptake takes precedence over oxidative phosphorylation of ADP for respiratory energy. Once Ca2+ is accumulated by the crab mitochondria, it is stable and only very slowly released, even by uncoupling agents. ATP hydrolysis also supports Ca2+ uptake. Respiration-inhibited crab hepatopancreas mitochondria show both high-affinity and low-affinity Ca2+-binding sites, which are inactive in the presence of uncoupling agents. Crab hepatopancreas mitochondria have an enormous capacity for accumulation of Ca2+, up to 5,500 ng-atoms Ca2+ per mg protein, with an equivalent amount of phosphate. Freshly isolated mitochondria contain very large amounts of Ca2+, Mg2+, phosphate, K+, and Na+; their high Ca2+ content is a reflection of the vary large amount of extra-mitochondrial Ca2+ in the whole tissue. Electron microscopy of crab mitochondria loaded with Ca2+ and phosphate showed large electron-dense deposits, presumably of precipitated calcium phosphate. They consisted of bundles of needle-like crystals, whereas Ca2+-loaded rat liver mitochondria show only amorphous deposits of calcium phosphate under similar conditions. The very pronounced capacity of crab hepatopancreas mitochondria for transport of Ca2+ appears to be adapted to a role in the storage and release of Ca2+ during the molting cycle of this crustacean. PMID:4827906

  5. A comparison of methane emissions following rice paddies conversion to crab-fish farming wetlands in southeast China.

    Science.gov (United States)

    Hu, Zhiqiang; Wu, Shuang; Ji, Cheng; Zou, Jianwen; Zhou, Quansuo; Liu, Shuwei

    2016-01-01

    Rice paddies and aquaculture wetlands are typical agricultural wetlands that constitute one of the important sources of atmospheric methane (CH4). Traditional transplanted rice paddies have been experiencing conversion to pond aquaculture wetlands for pursuing higher economic benefits over the past decades in southeast China. A parallel field experiment was carried out to compare CH4 emissions from a transplanted rice paddy and its converted crab-fish farming wetland in southeast China. Over the rice-growing season, CH4 fluxes averaged 1.86 mg m(-2) h(-1) from rice paddies, and 1.14 and 0.50 mg m(-2) h(-1) for the treatments with or without aquatic vegetation present in the crab-fish farming wetlands, respectively. When averaged across the treatments, seasonal CH4 emissions from crab-fish framing wetlands were 52% lower than those from rice paddies. The CH4 fluxes were negatively related to water dissolved oxygen (DO) concentration but positively related to soil/sediment dissolved organic carbon (DOC) content in crab-fish farming wetlands. Dependence of CH4 fluxes on DO or DOC was intensified by the aquatic vegetation presence. By extrapolating the present CH4 emission rate with the current rice paddy-converted aquaculture cultivation area, the seasonal CH4 emissions from inland aquaculture wetlands during the critical farming stage (20 June to 18 October) were estimated to be 33.6 Gg ha(-1) in southeast China in 2012. Rice paddies conversion to crab-fish farming wetlands might have reduced CH4 emissions by 22-54% in mainland China. Results of this study suggest that the conversion of transplanted rice paddies to crab-fish aquaculture wetlands for higher economic benefits would also lead to a lower ecosystem CH4 release rate.

  6. Mud crab susceptibility to disease from white spot syndrome virus is species-dependent

    Directory of Open Access Journals (Sweden)

    Sritunyalucksana Kallaya

    2010-11-01

    Full Text Available Abstract Background Based on a report for one species (Scylla serrata, it is widely believed that mud crabs are relatively resistant to disease caused by white spot syndrome virus (WSSV. We tested this hypothesis by determining the degree of susceptibility in two species of mud crabs, Scylla olivacea and Scylla paramamosain, both of which were identified by mitochondrial 16 S ribosomal gene analysis. We compared single-dose and serial-dose WSSV challenges on S. olivacea and S. paramamosain. Findings In a preliminary test using S. olivacea alone, a dose of 1 × 106 WSSV copies/g gave 100% mortality within 7 days. In a subsequent test, 17 S. olivacea and 13 S. paramamosain were divided into test and control groups for challenge with WSSV at 5 incremental, biweekly doses starting from 1 × 104 and ending at 5 × 106 copies/g. For 11 S. olivacea challenged, 3 specimens died at doses between 1 × 105 and 5 × 105 copies/g and none died for 2 weeks after the subsequent dose (1 × 106 copies/g that was lethal within 7 days in the preliminary test. However, after the final challenge on day 56 (5 × 106 copies/g, the remaining 7 of 11 S. olivacea (63.64% died within 2 weeks. There was no mortality in the buffer-injected control crabs. For 9 S. paramamosain challenged in the same way, 5 (55.56% died after challenge doses between 1 × 104 and 5 × 105 copies/g, and none died for 2 weeks after the challenge dose of 1 × 106 copies/g. After the final challenge (5 × 106 copies/g on day 56, no S. paramamosain died during 2 weeks after the challenge, and 2 of 9 WSSV-infected S. paramamosain (22.22% remained alive together with the control crabs until the end of the test on day 106. Viral loads in these survivors were low when compared to those in the moribund crabs. Conclusions S. olivacea and S. paramamosain show wide variation in response to challenge with WSSV. S. olivacea and S. paramamosain are susceptible to white spot disease, and S. olivacea is more

  7. Mud crab susceptibility to disease from white spot syndrome virus is species-dependent.

    Science.gov (United States)

    Somboonna, Naraporn; Mangkalanan, Seksan; Udompetcharaporn, Attasit; Krittanai, Chartchai; Sritunyalucksana, Kallaya; Flegel, Tw

    2010-11-20

    Based on a report for one species (Scylla serrata), it is widely believed that mud crabs are relatively resistant to disease caused by white spot syndrome virus (WSSV). We tested this hypothesis by determining the degree of susceptibility in two species of mud crabs, Scylla olivacea and Scylla paramamosain, both of which were identified by mitochondrial 16 S ribosomal gene analysis. We compared single-dose and serial-dose WSSV challenges on S. olivacea and S. paramamosain. In a preliminary test using S. olivacea alone, a dose of 1 × 106 WSSV copies/g gave 100% mortality within 7 days. In a subsequent test, 17 S. olivacea and 13 S. paramamosain were divided into test and control groups for challenge with WSSV at 5 incremental, biweekly doses starting from 1 × 104 and ending at 5 × 106 copies/g. For 11 S. olivacea challenged, 3 specimens died at doses between 1 × 105 and 5 × 105 copies/g and none died for 2 weeks after the subsequent dose (1 × 106 copies/g) that was lethal within 7 days in the preliminary test. However, after the final challenge on day 56 (5 × 106 copies/g), the remaining 7 of 11 S. olivacea (63.64%) died within 2 weeks. There was no mortality in the buffer-injected control crabs. For 9 S. paramamosain challenged in the same way, 5 (55.56%) died after challenge doses between 1 × 104 and 5 × 105 copies/g, and none died for 2 weeks after the challenge dose of 1 × 106 copies/g. After the final challenge (5 × 106 copies/g) on day 56, no S. paramamosain died during 2 weeks after the challenge, and 2 of 9 WSSV-infected S. paramamosain (22.22%) remained alive together with the control crabs until the end of the test on day 106. Viral loads in these survivors were low when compared to those in the moribund crabs. S. olivacea and S. paramamosain show wide variation in response to challenge with WSSV. S. olivacea and S. paramamosain are susceptible to white spot disease, and S. olivacea is more susceptible than S. paramamosain. Based on our single

  8. Phase Evolution of the Crab Pulsar between Radio and X-Ray

    Energy Technology Data Exchange (ETDEWEB)

    Yan, L. L.; Ge, M. Y.; Zheng, S. J.; Lu, F. J.; Tuo, Y. L.; Zhang, S. N.; Lu, Y. [Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Yuan, J. P.; Tong, H. [Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi, Xinjiang 830011 (China); Han, J. L. [National Astronomical Observatory, Chinese Academy of Sciences, Jia 20 Datun Road, Beijing 100012 (China); Du, Y. J., E-mail: yanlinli@ihep.ac.cn [Qian Xuesen Laboratory of Space Technology, No. 104, Youyi Road, Haidian District, Beijing 100094 (China)

    2017-08-20

    We study the X-ray phases of the Crab pulsar utilizing the 11-year observations from the Rossi X-ray Timing Explorer , 6-year radio observations from Nanshan Telescope, and the ephemeris from Jodrell Bank Observatory. It is found that the X-ray phases in different energy bands and the radio phases from the Nanshan Telescope show similar behaviors, including long-time evolution and short-time variations. Such strong correlations between the X-ray and radio phases imply that the radio and X-ray timing noises are both generated from the pulsar spin that cannot be well described by the the monthly ephemeris from the Jodrell Bank observatory. When using the Nanshan phases as references to study the X-ray timing noise, it has a significantly smaller variation amplitude and shows no long-time evolution, with a change rate of (−1.1 ± 1.1) × 10{sup −7} periods per day. These results show that the distance of the X-ray and radio emission regions on the Crab pulsar has no detectable secular change, and it is unlikely that the timing noises resulted from any unique physical processes in the radio or X-ray emitting regions. The similar behaviors of the X-ray and radio timing noises also imply that the variation of the interstellar medium is not the origin of the Crab pulsar’s timing noises, which is consistent with the results obtained from the multi-frequency radio observations of PSR B1540−06.

  9. Metabolic Response of Dungeness Crab Larvae Exposed to Elevated CO2 and Hypoxia

    Science.gov (United States)

    Nichols, Z.; Busch, S.; McElhany, P.

    2015-12-01

    Ocean acidification (OA) and deoxygenation, both resulting from rising atmospheric CO2 levels, are lowering the pH and oxygen levels of global oceans. Assessing the impacts of OA and deoxygenation on harvested species is crucial for guiding resource management with the aim of maintaining healthy and sustainable populations. The Dungeness crab, Cancer magister, is an important species ecologically and economically for the US West Coast. Crabs transition through four main stages: zoea, megalopa, juvenile, and adult. Each stage results in a different morphology and behavior, and as a result, is exposed to various environmental parameters, such as pH and dissolved oxygen (DO). The first two stages exhibit diel vertical migration while the final stages are benthic. Our study focused on the megalopae stage and their metabolic response to OA and hypoxia. We exposed wild-caught megalopae to a pH x DO cross, producing treatment waters with combinations of low or high pH and O2, all maintained at 12˚C. Closed-chamber respirometry was used to compare standard metabolic rates in a common garden setting with high pH/high DO conditions. We predict that the megalopae exposed to the low pH/high DO treatment will have a higher metabolic rate than those exposed to the high pH/high DO treatment. This may be a result of homeostatic processes increasing to return the megalopae's internal pH back to equilibrium. We predict that the high pH/low DO treatment will cause a decrease in metabolism when compared to the high pH/high DO treatment due to the megalopae conserving oxygen in a limiting environment. If results support our hypothesis, they would suggest that OA and hypoxia affects Dungeness crabs in sublethal ways.

  10. Cadmium, zinc and the uptake of calcium by two crabs, Carcinus maenas and Eriocheir sinensis

    International Nuclear Information System (INIS)

    Rainbow, P.S.; Black, W.H.

    2005-01-01

    The uptake of dissolved cadmium and zinc by crustaceans can usually be explained by the passive process of facilitated diffusion involving a transport protein in the membranes of permeable surfaces. Cadmium ions will also enter via uptake routes for calcium, given the similar size of the two free ions. This study has investigated the interaction of cadmium (and comparatively zinc) and calcium uptake in two crabs that show different permeability responses to changes in salinity, with consequently different effects on the uptake of cadmium and zinc with salinity change. Ca uptake rates in Carcinus maenas decreased in reduced salinity (33-15) with the decreased Ca concentration of the medium and increased if the Ca concentration was increased at salinity 20. It is concluded that Ca uptake over the salinity range 33-15 is via apical Ca channels in gill ionocytes, passively down an electrochemical gradient. The Ca uptake rate of Eriocheir sinensis showed no significant decrease over the salinity range 33-10 (probably because of the small differences in an already low Ca uptake rate in this crab against a background of inter-individual variability), but decreased significantly at salinity 5. Added calcium increased the Ca uptake rate of E. sinensis at salinities 15 and 5, supporting the interpretation that Ca uptake in gills is typically passive via apical Ca channels. Cadmium (but not zinc) inhibited calcium uptake in both crabs at 15 salinity, indicating sharing of Ca channels by Cd, but not at salinity 5 (E. sinensis only) when Ca may be taken up into gill ionocytes by another (active?) physiological process

  11. Turbine sound may influence the metamorphosis behaviour of estuarine crab megalopae.

    Directory of Open Access Journals (Sweden)

    Matthew K Pine

    Full Text Available It is now widely accepted that a shift towards renewable energy production is needed in order to avoid further anthropogenically induced climate change. The ocean provides a largely untapped source of renewable energy. As a result, harvesting electrical power from the wind and tides has sparked immense government and commercial interest but with relatively little detailed understanding of the potential environmental impacts. This study investigated how the sound emitted from an underwater tidal turbine and an offshore wind turbine would influence the settlement and metamorphosis of the pelagic larvae of estuarine brachyuran crabs which are ubiquitous in most coastal habitats. In a laboratory experiment the median time to metamorphosis (TTM for the megalopae of the crabs Austrohelice crassa and Hemigrapsus crenulatus was significantly increased by at least 18 h when exposed to either tidal turbine or sea-based wind turbine sound, compared to silent control treatments. Contrastingly, when either species were subjected to natural habitat sound, observed median TTM decreased by approximately 21-31% compared to silent control treatments, 38-47% compared to tidal turbine sound treatments, and 46-60% compared to wind turbine sound treatments. A lack of difference in median TTM in A. crassa between two different source levels of tidal turbine sound suggests the frequency composition of turbine sound is more relevant in explaining such responses rather than sound intensity. These results show that estuarine mudflat sound mediates natural metamorphosis behaviour in two common species of estuarine crabs, and that exposure to continuous turbine sound interferes with this natural process. These results raise concerns about the potential ecological impacts of sound generated by renewable energy generation systems placed in the nearshore environment.

  12. Spermatophore transfer in the hermit crab Clibanarius vittatus (Crustacea, Anomura, Diogenidae).

    Science.gov (United States)

    Hess, Gregory S; Bauer, Raymond T

    2002-08-01

    Although mating has been described in several hermit crab species, the mechanics of spermatophore transfer have not previously been demonstrated. Evidence from pleopod and gonopore morphology, video observations, and inseminated females indicates that in Clibanarius vittatus the male applies a spermatophoric mass directly onto the female via the gonopores rather than with modified pleopods 1-2 (gonopods) and/or genital papillae as in many other decapods. The single second pleopod of males of C. vittatus has a simple endopod with no apparent modifications for sperm transfer. There are no genital papillae extending from the male gonopores. The globular spermatophores are aligned in rows surrounded by a seminal secretion in the male ducts (vasa deferentia that terminate in ejaculatory ducts opening to the exterior via the gonopores). During copulation, described from time-lapse video recordings, the ventral surface of the last thoracic segment of the male, bearing the gonopores, was apposed to the ventral cephalothorax of the female. A massive amount of seminal secretion containing spermatophore ribbons, termed here the spermatophoric mass and described for the first time in a hermit crab species, was observed covering the sternites and coxae of pereopods 1-5 of a recently copulated female. It is suggested that during copulation the male emits the contents of the ejaculatory ducts directly onto the female without the aid of gonopods or genital papillae. Although spermatophore transfer is simple in C. vittatus, the presence of modified anterior pleopods or elongate genital papillae (sexual tubes) in other paguroidean species suggests the possibility of a more complex insemination process in these other hermit crabs. Copyright 2002 Wiley-Liss, Inc.

  13. Hard x-ray to low energy gamma ray spectrum of the Crab Nebula

    International Nuclear Information System (INIS)

    Jung, G.V.

    1986-01-01

    The spectrum of the Crab Nebula has been determined in the energy range 10 keV to 5 MeV from the data of the UCSD/MIT Hard-X-ray and Low Energy Gamma Ray Experiment on the first High Energy Astronomy Observatory, HEAO-1. The x-ray to γ-ray portion of the continuous emission from the Crab is indicative of the electron spectrum, its transport through the nebula, and the physical conditions near the shocked interface between the nebular region and the wind which is the physical link between the nebula and the pulsar, NP0532. The power-law dependence of the spectrum found in the lower-energy decade of this observation (10 to 100 keV) is not continued without modification to higher energies. Evidence for this has been accumulating from previous observations in the γ-ray ranges of 1-10 MeV and above 35 MeV. The observations on which this dissertation is based further characterize the spectral change in the 100 keV to 1 MeV region. These observations provide a crucial connection between the x-ray and γ-ray spectrum of the non-pulsed emission of the Crab Nebula. The continuity of this spectrum suggests that the emission mechanism responsible for the non-pulsed γ-rays observed above 35 MeV is of the same origin as the emission at lower energies, i.e. that of synchrotron radiation in the magnetic field of the nebula

  14. Turbine Sound May Influence the Metamorphosis Behaviour of Estuarine Crab Megalopae

    Science.gov (United States)

    Pine, Matthew K.; Jeffs, Andrew G.; Radford, Craig A.

    2012-01-01

    It is now widely accepted that a shift towards renewable energy production is needed in order to avoid further anthropogenically induced climate change. The ocean provides a largely untapped source of renewable energy. As a result, harvesting electrical power from the wind and tides has sparked immense government and commercial interest but with relatively little detailed understanding of the potential environmental impacts. This study investigated how the sound emitted from an underwater tidal turbine and an offshore wind turbine would influence the settlement and metamorphosis of the pelagic larvae of estuarine brachyuran crabs which are ubiquitous in most coastal habitats. In a laboratory experiment the median time to metamorphosis (TTM) for the megalopae of the crabs Austrohelice crassa and Hemigrapsus crenulatus was significantly increased by at least 18 h when exposed to either tidal turbine or sea-based wind turbine sound, compared to silent control treatments. Contrastingly, when either species were subjected to natural habitat sound, observed median TTM decreased by approximately 21–31% compared to silent control treatments, 38–47% compared to tidal turbine sound treatments, and 46–60% compared to wind turbine sound treatments. A lack of difference in median TTM in A. crassa between two different source levels of tidal turbine sound suggests the frequency composition of turbine sound is more relevant in explaining such responses rather than sound intensity. These results show that estuarine mudflat sound mediates natural metamorphosis behaviour in two common species of estuarine crabs, and that exposure to continuous turbine sound interferes with this natural process. These results raise concerns about the potential ecological impacts of sound generated by renewable energy generation systems placed in the nearshore environment. PMID:23240063

  15. PROPERTIES AND SPATIAL DISTRIBUTION OF DUST EMISSION IN THE CRAB NEBULA

    Energy Technology Data Exchange (ETDEWEB)

    Temim, Tea; Sonneborn, George; Dwek, Eli; Arendt, Richard G. [Observational Cosmology Lab, Code 665, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Gehrz, Robert D. [Minnesota Institute for Astrophysics, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States); Slane, Patrick [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Roellig, Thomas L., E-mail: tea.temim@nasa.gov [NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035-1000 (United States)

    2012-07-01

    Recent infrared (IR) observations of freshly formed dust in supernova remnants have yielded significantly lower dust masses than predicted by theoretical models and measured from high-redshift observations. The Crab Nebula's pulsar wind is thought to be sweeping up freshly formed supernova (SN) dust along with the ejected gas. The evidence for this dust was found in the form of an IR excess in the integrated spectrum of the Crab and in extinction against the synchrotron nebula that revealed the presence of dust in the filament cores. We present the first spatially resolved emission spectra of dust in the Crab Nebula acquired with the Infrared Spectrograph on board the Spitzer Space Telescope. The IR spectra are dominated by synchrotron emission and show forbidden line emission from S, Si, Ne, Ar, O, Fe, and Ni. We derived a synchrotron spectral map from the 3.6 and 4.5 {mu}m images, and subtracted this contribution from our data to produce a map of the residual continuum emission from dust. The dust emission appears to be concentrated along the ejecta filaments and is well described by an amorphous carbon or silicate grain compositions. We find a dust temperature of 55 {+-} 4 K for silicates and 60 {+-} 7 K for carbon grains. The total estimated dust mass is (1.2-12) Multiplication-Sign 10{sup -3} M{sub Sun }, well below the theoretical dust yield predicted for a core-collapse supernova. Our grain heating model implies that the dust grain radii are relatively small, unlike what is expected for dust grains formed in a Type IIP SN.

  16. Accumulation and depuration of okadaic acid esters in the European green crab ( Carcinus maenas ) during a feeding study

    DEFF Research Database (Denmark)

    Jørgensen, Kevin; Cold, Ulrik; Fischer, Knud

    2008-01-01

    in the product could be a food safety problem. The crabs were fed with mussels containing DSP toxins (2500 mu g total okadaic acid equivalents/kg) for 17 days and then fasted for 19 days. The content of total okadaic acid equivalents in the digestive organs was on average 27 times higher than the corresponding...... content in the body meat. The highest level of total okadaic acid equivalents measured was 12 mu g/kg in body meat and 503 mu g/kg in digestive organs. The results show that the content of DSP toxins in a commercial product of soft shell European green crab (without digestive organs) could be regarded...

  17. First discovery of porcellanid crab, Porcellanella picta (Crustacea: Decapoda: Porcellanidae, from south-east coast of India

    Directory of Open Access Journals (Sweden)

    Kanagasabapathy Sivasubramanian

    2014-09-01

    Full Text Available Studies of the distribution of any marine organism are very important in determining the range of its expansion in the oceans and to determine the factors influencing this expansion. This study reports for the first time the occurrence of the crab Porcellanella picta (Crustacea, Anomura, Porcellanidae in the Point Calimere coastal region of southeastern India. All the specimens found were sexually mature. This crab occurs only rarely on the Indian coast and this observation expands its known range, recording a second distributional area for the species and significantly extending its range on the southeast coast of India.

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

    Science.gov (United States)

    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

  19. Mechanisms causing size differences of the land hermit crab Coenobita rugosus among eco-islands in Southern Taiwan.

    Directory of Open Access Journals (Sweden)

    Chia-Hsuan Hsu

    Full Text Available Numerous environmental factors can influence body size. Comparing populations in different ecological contexts is one potential approach to elucidating the most critical of such factors. In the current study, we found that the body size of the land hermit crab Coenobita rugosus was significantly larger on Dongsha Island in the South China Sea than on other eco-islands around Southern Taiwan. We hypothesized that this could be due to differences in (1 shell resources, (2 parasite impact, (3 competition, (4 predation, and (5 food. We found no supporting evidence for the first three hypotheses; the shells used by the hermit crabs on Dongsha were in poorer condition than were those used elsewhere, extremely few individuals in the region had ectoparasites, and the density of hermit crabs varied considerably among localities within each island. However, significantly higher percentages of C. rugosus reached age 3 years on Dongsha than at Siziwan bay in Taiwan. Two growth rate indices inferred from size structures suggested faster growth on Dongsha than at Siziwan. The condition index (i.e., the body mass/shield length ratio of C. rugosus was also greater on Dongsha than at Siziwan. Therefore, Dongsha hermit crabs seem to have superior diet and growth performance. Seagrass debris accumulation at the shore of Dongsha was considerable, whereas none was observed at Siziwan or on the other islands, where dicot leaves were the dominant food item for the vegetarian hermit crabs. We then experimentally evaluated the possible role of seagrass as food for C. rugosus. The crabs on Dongsha preferred seagrass to dicot leaves, and their growth increment was faster when they fed on seagrass than when they fed on dicot leaves; no such differences were found in the Siziwan hermit crabs. The aforementioned results are compatible with the food hypothesis explaining the size differences among the islands. The predator hypothesis could explain the greater life span but

  20. Intersexuality in the porcellanid crab Pisidia longicornis (Crustacea: Decapoda: Anomura: Porcellanidae

    Directory of Open Access Journals (Sweden)

    Luciane Augusto de Azevedo Ferreira

    2015-04-01

    Full Text Available Intersex specimens of Pisidia longicornis (Linnaeus, 1767 are recorded for the first time and their secondary sexual characters are analyzed. Of 145 specimens of P. longicornis examined in this study, six were identified as intersex individuals. Of these, three presented male secondary sexual characters, well-developed male gonopores and rudimentary female gonopores, whereas the other three had female secondary sexual characters, with female gonopores being more pronounced than the male ones. The present study provides the first record of intersex porcelain crabs.

  1. Crab Cavity and Cryomodule Prototype Development for the Advanced Photon Source

    Energy Technology Data Exchange (ETDEWEB)

    Wang, H; Ciovati, G; Clemens, W A; Henry, J; Kneisel, P; Kushnick, P; Macha, K; Mammosser, J D; Rimmer, R A; Slack, G; Turlington, L; Nassiri, R; Waldschmidt, G J; Wu, G

    2011-03-01

    We review the single-cell, superconducting crab cavity designs for the short-pulse x-ray (SPX) project at the Advanced Photon Source (APS). The 'on-cell' waveguide scheme is expected to have a more margin for the impedance budget of the APS storage ring, as well as offering a more compact design compared with the original design consisting of a low order mode damping waveguide on the beam pipe. We will report recent fabrication progress, cavity test performance on original and alternate prototypes, and concept designs and analysis for various cryomodule components.

  2. Morphometric comparison between hatchery-reared and wild-caught megalopae of the mangrove crab

    Directory of Open Access Journals (Sweden)

    Bárbara Andressa Casagrande Ayres

    2013-08-01

    Full Text Available The objective of this work was to compare the morphometry of hatchery-reared and wild-caught mangrove crab (Ucides cordatus megalopae. Ten U. cordatus megalopae of each group (hatchery-reared and wild-caught were individually analyzed using a stereoscopic microscope equipped with an ocular micrometer. Length, width, and height of all megalopae were measured, and the size of body appendices was determined. The results indicate that the hatchery-reared megalopae are more robust than the wild ones. Furthermore, some significant differences in the size of certain appendices can be cues of the kind of alterations that hatchery-reared individuals experience.

  3. On Calibrations Using the Crab Nebula and Models of the Nebular X-Ray Emission

    Science.gov (United States)

    Weisskopf, M. C.; Guainazzi, M.; Jahoda, K.; Shaposhnikov, N.; O'Dell, S. L.; Zavlin, V. E.; Wilson-Hodge, C.; Elsner, R. F.

    2010-04-01

    Motivated by a paper of Kirsch et al. on possible use of the Crab Nebula as a standard candle for calibrating X-ray response functions, we examine consequences of intrinsic departures from a single (absorbed) power law upon such calibrations. We limit our analyses to three more modern X-ray instruments—the ROSAT/PSPC, the RXTE/Proportional Counter Array, and the XMM-Newton/EPIC-pn (burst mode). The results indicate a need to refine two of the three response functions studied. We are also able to distinguish between two current theoretical models for the system spectrum.

  4. Bionomics of brown crab Cancer pagurus in the south east Ireland inshore fishery

    OpenAIRE

    Fahy, E.; Hickey, J.; Perella, N.; Hervas, A.; Carroll, J.; Andray, C.

    2004-01-01

    The south east inshore brown crab fishery is delimited by the boundary of longitude - 6.3, within a coastal band of approximately 18 km (10 nm) in width and it extends along the south coast of Co Wexford for a distance of approximately 55 km; evidence for the stock extending into the inshore fishery west of the Waterford Harbour estuary is sparse. The fishery, whose maximum extent is calculated at 427 km2, yielded up to 700 t per year during the 1990s. In 2002 annual landings of 959 t account...

  5. A new species of the hermit crab genus Diogenes (Crustacea: Decapoda: Anomura: Diogenidae) from southern India.

    Science.gov (United States)

    Komai, Tomoyuki; Reshmi, Rema; Kumar, Appukuttannair Biju

    2013-02-12

    A new species of the hermit crab genus Diogenes Dana, 1851 (Diogenidae), D. canaliculatus, is described and illustrated on the basis of material from off the Kerala State, southern India. It is referred to the D. edwardsii (De Haan, 1849) species group, and compared with D. bicristimanus Alcock, 1905, D. fasciatus Rahayu & Forest, 1995, D. laevicarpus Rahayu, 1996 and D. moosai Rahayu & Forest, 1995. The characteristically sculptured left chela and the unarmed dorsal margins of the propodi of the second and third pereopods distinguish the new species from these congeners.

  6. Characterization of cadmium plasma membrane transport in gills of a mangrove crab Ucides cordatus

    Energy Technology Data Exchange (ETDEWEB)

    Ortega, P.; Custódio, M.R. [Instituto de Biociências, Departamento de Fisiologia, Universidade de São Paulo, Rua do Matão, Travessa 14, #101, São Paulo 05508-900, SP (Brazil); Zanotto, F.P., E-mail: fzanotto@usp.br [Instituto de Biociências, Departamento de Fisiologia, Universidade de São Paulo, Rua do Matão, Travessa 14, #101, São Paulo 05508-900, SP (Brazil); Departamento de Biofísica, Escola Paulista de Medicina, Universidade Federal de São Paulo, Rua Três de Maio 100, São Paulo 04044-020 (Brazil)

    2014-12-15

    Highlights: • Cd{sup 2+} gill cell transport, a non-essential toxic metal, was characterized in a hypo-hyper-regulating mangrove crab Ucides cordatus. • Cd{sup 2+} enter gill cells through Ca{sup 2+} channels and is dependent of intracellular Ca{sup 2+} levels. • Route of entry in gill cells also involves a Cd{sup 2+}/Ca{sup 2+} (2Na) exchanger. • Cd transport depends on Na{sup +}/K{sup +}-ATPase and gill cell electrochemical gradient. • Vanadate inhibits gill Cd{sup 2+} transport and ouabain increase gill Cd{sup 2+} transport. - Abstract: Membrane pathway for intracellular cadmium (Cd{sup 2+}) accumulation is not fully elucidated in many organisms and has not been studied in crab gill cells. To characterize membrane Cd{sup 2+} transport of anterior and posterior gill cells of Ucides cordatus, a hypo-hyper-regulating crab, a change in intracellular Cd{sup 2+} concentration under various experimental conditions was examined by using FluoZin, a fluorescent probe. The membrane Cd{sup 2+} transport was estimated by the augmentation of FluoZin fluorescence induced by extracellular application of CdCl{sub 2} and different inhibitors. Addition of extracellular calcium (Ca{sup 2+}) to the cells affected little the fluorescence of FluoZin, confirming that Cd{sup 2+} was the main ion increasing intracellular fluorescence. Ca{sup 2+} channels blockers (nimodipine and verapamil) decreased Cd{sup 2+} influx as well as vanadate, a Ca{sup 2+}-ATPase blocker. Chelating intracellular Ca{sup 2+} (BAPTA) decreased Cd{sup 2+} influx in gill cells, while increasing intracellular Ca{sup 2+} (caffeine) augmented Cd influx. Cd{sup 2+} and ATP added at different temporal conditions were not effective at increasing intracellular Cd{sup 2+} accumulation. Ouabain (Na{sup +}/K{sup +}-ATPase inhibitor) increased Cd{sup 2+} influx probably through a change in intracellular Na and/or a change in cell membrane potential. Routes of Cd{sup 2+} influx, a non-essential metal, through the

  7. Phase distribution of the 0.44 MeV feature in the Crab pulsar spectrum

    Science.gov (United States)

    Olive, J. F.; Agrinier, B.; Barouch, E.; Comte, R.; Costa, E.; Cusumano, G. C.; Gerardi, G.; Lemoine, D.; Mandrou, P.; Masnou, J. L.; Massaro, E.; Matt, G.; Mineo, T.; Niel, M.; Parlier, B.; Sacco, B.; Salvati, M.; Scarsi, L.

    1993-01-01

    On 1990 July 9, the balloon-borne experiment FIGARO II (0.15-4 MeV) observed the Crab region. The light-curve of PSR 0531 + 212 shows, in addition to the well-known two-peak structures, evidence for extra structures at absolute radio phases 0.1, 0.3, and 0.45 around the energy of 0.44 MeV. The phase-resolved spectroscopy confirms that an excess, compatible with a line-like feature, is present at these phase positions.

  8. A case for the commons: The Snow Crab in the Barents

    DEFF Research Database (Denmark)

    Kaiser, Brooks; Kourantidou, Melina; Fernandez, Linda

    2018-01-01

    the fish stocks, and manage for external costs and benefits from harvest. These may include ecosystem damages, overcapitalization in the fishery, and/or equity concerns. Regulatory efforts and related rights-based management instruments may increase the returns to fishery stakeholders but miss important......, article 77, part VI)). This shifts the regulatory environment for the crab in ways that exacerbate the invasion in exchange for protection of local gains. Such problems will increase in magnitude and impact as climate changes increasingly affect species' ranges. Optimal decision-making regarding...

  9. Hermit crab (Decapoda, Anomura attraction to dead gastropod baits in an infralittoral algae bank

    Directory of Open Access Journals (Sweden)

    Juarez C. B. Pezzuti

    2002-06-01

    Full Text Available Hermit crabs use gastropod shells as shelter and are adapted to follow chemical cues released from tissues of dead or injured gastropods as a way to find new and more adequate shells. The species composition, crab size, shell types adequacy and physical condition were compared between attracted individuals and crabs collected in previous samples. The previous sampling was carried out in five areas before each experiment. Then, five baits of crushed gastropods in nylon net bags were installed in these areas. Three samples were taken at 30min intervals, capturing all crabs within a circle of 60cm diameter. Attraction of hermit crabs was tested for four different gastropod baits to verify specificity of the chemical cues. Clibanarius antillensis, Pagurus brevidactylus and Paguristes tortugae were collected in the study area. Pagurus brevidactylus, the smallest species, turned out to be more attracted than the 2 other species. The results showed that attracted crabs utilized more gastropod shell types than that collected in previous samples, however shell utilization pattern did not differ between them. Attracted animals were slightly smaller (shield length than those collected in the previous samples but did not present significant differences in shell adequacy and condition. The four experimental baits attracted the crabs in similar ways not indicating a specific response from the crabs. The fact that attracted animals were smaller suggested that the attraction to dead gastropods might enable the acquisition of a new and larger shell and, consequently, chains of shell exchange between the attracted crabs.Ermitões utilizam conchas de gastrópodes para abrigo. Conchas novas e mais adequadas podem ser encontradas pelos ermitões pois estes são atraídos por substâncias químicas liberadas pelos tecidos de gastrópodes feridos ou mortos. A adequação, condição e tipo das conchas e a composição de espécies e o tamanho dos ermitões foram

  10. 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.

  11. Effects of an Offshore Wind Farm (OWF on the Common Shore Crab Carcinus maenas: Tagging Pilot Experiments in the Lillgrund Offshore Wind Farm (Sweden.

    Directory of Open Access Journals (Sweden)

    Olivia Langhamer

    Full Text Available Worldwide growth of offshore renewable energy production will provide marine organisms with new hard substrate for colonization in terms of artificial reefs. The artificial reef effect is important when planning offshore installations since it can create habitat enhancement. Wind power is the most advanced technology within offshore renewable energy sources and there is an urgent need to study its impacts on the marine environment. To test the hypothesis that offshore wind power increases the abundance of reef species relative to a reference area, we conduct an experiment on the model species common shore crab (Carcinus maenas.Overall, 3962 crabs were captured, observed, marked and released in 2011 and 1995 crabs in 2012. Additionally, carapace size, sex distribution, color morphs and body condition was recorded from captured crabs. We observed very low recapture rates at all sites during both years which made evaluating differences in population sizes very difficult. However, we were able to estimate population densities from the capture record for all three sites. There was no obvious artificial reef effect in the Lillgrund wind farm, but a spill-over effect to nearby habitats cannot be excluded. We could not find any effect of the wind farm on either, morphs, sex distribution or condition of the common shore crab. Our study found no evidence that Lillgrund wind farm has a negative effect on populations of the common shore crab. This study provides the first quantitative and experimental data on the common shore crab in relation to offshore wind farms.

  12. Seasonal dynamics of the density of the crab larvae (Decapoda: Brachyura et Anomura) in Minonosok Bay of Pos'eta Bay (Peter the Great Bay, Sea of Japan)

    Science.gov (United States)

    Grigoryeva, N. I.

    2013-03-01

    As the materials for this project, we used data on the distribution of the larvae of the Asian paddle crab Charybdis japonicus (A. Milne-Edwards, 1861); the spider crabs Hyas coarctatus ursinus (= Hyas ursinus) (Rathbun, 1924), Pugettia quadridens (de Haan, 1839), and Pisoides bidentatus (H. Milne-Edwards, 1873); the samurai crab Paradorippe granulata (= Dorippe granulata) (de Haan, 1841); the pea crab Pinnixa rathbuni (Sakai, 1934); and the porcelain crab Pachycheles stevensii (Stimpson, 1858) in Minonosok Bay of Pos'eta Bay obtained during 2000-2002 and in 2004. The planktonic samples were collected from the last third of May to September. The greatest density of the larvae was observed in May, mid-June, late June-early July, and late July-early August. The greatest densities of the crab larvae and the decapod larvae ranged from 20.4 to 48.2 and from 88.4 to 245.3 specimens/m3. The schedule of the crab larvae's occurrence in the plankton is provided for the first time. The distribution of the density showed pronounced patchiness.

  13. Using underwater video to evaluate the performance of the Fukui trap as a mitigation tool for the invasive European green crab (Carcinus maenas) in Newfoundland, Canada

    Science.gov (United States)

    McKenzie, Cynthia H.; Best, Kiley; Zargarpour, Nicola; Favaro, Brett

    2018-01-01

    The European green crab (Carcinus maenas) is a destructive marine invader that was first discovered in Newfoundland waters in 2007 and has since become established in nearshore ecosystems on the south and west coast of the island. Targeted fishing programs aimed at removing green crabs from invaded Newfoundland ecosystems use Fukui traps, but the capture efficiency of these traps has not been previously assessed. We assessed Fukui traps using in situ observation with underwater video cameras as they actively fished for green crabs. From these videos, we recorded the number of green crabs that approached the trap, the outcome of each entry attempt (success or failure), and the number of exits from the trap. Across eight videos, we observed 1,226 green crab entry attempts, with only a 16% rate of success from these attempts. Based on these observations we believe there is scope to improve the performance of the Fukui trap through modifications in order to achieve a higher catch per unit effort (CPUE), maximizing trap usage for mitigation. Ultimately, a more efficient Fukui trap will help to control green crab populations in order to preserve the function and integrity of ecosystems invaded by the green crab. PMID:29340237

  14. Comparison of automated BAX PCR and standard culture methods for detection of Listeria monocytogenes in blue Crabmeat (Callinectus sapidus) and blue crab processing plants.

    Science.gov (United States)

    Pagadala, Sivaranjani; Parveen, Salina; Schwarz, Jurgen G; Rippen, Thomas; Luchansky, John B

    2011-11-01

    This study compared the automated BAX PCR with the standard culture method (SCM) to detect Listeria monocytogenes in blue crab processing plants. Raw crabs, crabmeat, and environmental sponge samples were collected monthly from seven processing plants during the plant operating season, May through November 2006. For detection of L. monocytogenes in raw crabs and crabmeat, enrichment was performed in Listeria enrichment broth, whereas for environmental samples, demi-Fraser broth was used, and then plating on both Oxford agar and L. monocytogenes plating medium was done. Enriched samples were also analyzed by BAX PCR. A total of 960 samples were examined; 59 were positive by BAX PCR and 43 by SCM. Overall, there was no significant difference (P ≤ 0.05) between the methods for detecting the presence of L. monocytogenes in samples collected from crab processing plants. Twenty-two and 18 raw crab samples were positive for L. monocytogenes by SCM and BAX PCR, respectively. Twenty and 32 environmental samples were positive for L. monocytogenes by SCM and BAX PCR, respectively, whereas only one and nine finished products were positive. The sensitivities of BAX PCR for detecting L. monocytogenes in raw crabs, crabmeat, and environmental samples were 59.1, 100, and 60%, respectively. The results of this study indicate that BAX PCR is as sensitive as SCM for detecting L. monocytogenes in crabmeat, but more sensitive than SCM for detecting this bacterium in raw crabs and environmental samples.

  15. Characterization and Molecular Epidemiology of a Fungal Infection of Edible Crabs (Cancer pagurus) and Interaction of the Fungus with the Dinoflagellate Parasite Hematodinium

    Science.gov (United States)

    Smith, Amanda L.; Hamilton, Kristina M.; Hirschle, Lucy; Wootton, Emma C.; Vogan, Claire L.; Pope, Edward C.; Eastwood, Daniel C.

    2013-01-01

    This study reports on an emerging fungal disease of the edible crab, Cancer pagurus. Juvenile (prerecruit) crabs were found to be subject to this disease condition during the months of May to September at two intertidal sites in South Wales, United Kingdom. Histopathology revealed that the fungi overwhelm the host response in the tissues, leading to progressive septicemia. The causative agent of this infection was isolated and grown in pure culture and was identified as a member of the Ophiocordyceps clade by sequencing of the small subunit of the fungal ribosomal DNA (rDNA). Of the crabs naturally infected with the fungus, 94% had a coinfection with the parasitic dinoflagellate Hematodinium species. To determine if there was any interaction between the two disease-causing agents, apparently fungus-free crabs, both with and without natural Hematodinium infections, were challenged with the fungal isolate. The presence of Hematodinium caused a significant reduction in fungal multiplication in the hemocoel of the crabs in comparison to that in Hematodinium-free individuals. Histopathology of coinfected crabs showed a systemic multiplication of Hematodinium within host tissues, leading to a rapid death, while Hematodinium-free crabs experimentally infected with the fungal isolate died due to fungal sepsis (septicemia) with the same characteristic pathology as seen in natural infections. PMID:23160130

  16. Vertical cold test of the crab cavity with a co-axial beam pipe

    International Nuclear Information System (INIS)

    Morita, Y.; Hara, K.; Hosoyama, K.; Kabe, A.; Kojima, Y.; Nakai, H.; Inoue, M.; Ohkubo, K.

    2003-01-01

    A crab cavity was designed for the KEKB electron-positron collider-accelerator. The aim of this cavity is to deflect the beam bunch and realize the crab-crossing scheme. The cavity, operating in the TM110 mode, has a squashed cell with a co-axial beam pipe coupling scheme to extract the lowest order mode (TM010). Operating voltage should be high enough to deflect a beam bunch for a finite beam-crossing angle. For the R and D of this complicated structure, we have fabricated a prototype cavity and a simplified inner conductor for the co-axial beam pipe structure. We tested the RF performance of the cavity with the inner conductor in a vertical cryostat. During the tests, a serious Q-degradation was observed, which is so called Hydrogen Q-disease'. A calorimetric RF loss measurement showed that the loss at the inner conductor is a cause of the Q-degradation. We applied a quick cool-down procedure to the inner conductor and achieved a required deflecting voltage. (author)

  17. Galactic Shapiro delay to the Crab pulsar and limit on weak equivalence principle violation

    Science.gov (United States)

    Desai, Shantanu; Kahya, Emre

    2018-02-01

    We calculate the total galactic Shapiro delay to the Crab pulsar by including the contributions from the dark matter as well as baryonic matter along the line of sight. The total delay due to dark matter potential is about 3.4 days. For baryonic matter, we included the contributions from both the bulge and the disk, which are approximately 0.12 and 0.32 days respectively. The total delay from all the matter distribution is therefore 3.84 days. We also calculate the limit on violations of Weak equivalence principle by using observations of "nano-shot" giant pulses from the Crab pulsar with time-delay <0.4 ns, as well as using time differences between radio and optical photons observed from this pulsar. Using the former, we obtain a limit on violation of Weak equivalence principle in terms of the PPN parameter Δ γ < 2.41× 10^{-15}. From the time-difference between simultaneous optical and radio observations, we get Δ γ < 1.54× 10^{-9}. We also point out differences in our calculation of Shapiro delay and that from two recent papers (Yang and Zhang, Phys Rev D 94(10):101501, 2016; Zhang and Gong, Astrophys J 837:134, 2017), which used the same observations to obtain a corresponding limit on Δ γ.

  18. Individual quality and personality: bolder males are less fecund in the hermit crab Pagurus bernhardus.

    Science.gov (United States)

    Bridger, Danielle; Bonner, Simon J; Briffa, Mark

    2015-03-22

    One explanation for animal personality is that different behavioural types derive from different life-history strategies. Highly productive individuals, with high growth rates and high fecundity, are assumed to live life at a fast pace showing high levels of boldness and risk taking, compared with less productive individuals. Here, we investigate among-individual differences in mean boldness (the inverse of the latency to recover from a startling stimulus) and in the consistency of boldness, in male hermit crabs in relation to two aspects of life-history investment. We assessed aerobic scope by measuring the concentration of the respiratory pigment haemocyanin, and we assessed fecundity by measuring spermatophore size. First, we found that individuals investing in large spermatophores also had high concentrations of haemocyanin. Using doubly hierarchical-generalized linear models to analyse longitudinal data on startle responses, we show that hermit crabs vary both in their mean response durations and in the consistency of their behaviour. Individual consistency was unrelated to haemocyanin concentration or spermatophore size, but mean startle response duration increased with spermatophore size. Thus, counter to expectations, it was the most risk-averse individuals, rather than the boldest and most risk prone, that were the most productive. We suggest that similar patterns should be present in other species, if the most productive individuals avoid risky behaviour. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  19. Larval development of the subantarctic king crabs Lithodes santolla and Paralomis granulosa reared in the laboratory

    Science.gov (United States)

    Calcagno, J. A.; Anger, K.; Lovrich, G. A.; Thatje, S.; Kaffenberger, A.

    2004-02-01

    The larval development and survival in the two subantarctic lithodid crabs Lithodes santolla (Jaquinot) and Paralomis granulosa (Molina) from the Argentine Beagle Channel were studied in laboratory cultures. In L. santolla, larval development lasted about 70 days, passing through three zoeal stages and the megalopa stage, with a duration of approximately 4, 7, 11 and 48 days, respectively. The larval development in P. granulosa is more abbreviated, comprising only two zoeal stages and the megalopa stage, with 6, 11 and 43 days' duration, respectively. In both species, we tested for effects of presence versus absence of food (Artemia nauplii) on larval development duration and survival rate. In P. granulosa, we also studied effects of different rearing conditions, such as individual versus mass cultures, as well as aerated versus unaerated cultures. No differences in larval development duration and survival were observed between animals subjected to those different rearing conditions. The lack of response to the presence or absence of potential food confirms, in both species, a complete lecithotrophic mode of larval development. Since lithodid crabs are of high economic importance in the artisanal fishery in the southernmost parts of South America, the knowledge of optimal rearing conditions for lithodid larvae is essential for future attempts at repopulating the collapsing natural stocks off Tierra del Fuego.

  20. HAWC Analysis of the Crab Nebula Using Neural-Net Energy Reconstruction

    Science.gov (United States)

    Marinelli, Samuel; HAWC Collaboration

    2017-01-01

    The HAWC (High-Altitude Water-Cherenkov) experiment is a TeV γ-ray observatory located 4100 m above sea level on the Sierra Negra mountain in Puebla, Mexico. The detector consists of 300 water-filled tanks, each instrumented with 4 photomuliplier tubes that utilize the water-Cherenkov technique to detect atmospheric air showers produced by cosmic γ rays. Construction of HAWC was completed in March, 2015. The experiment's wide field of view (2 sr) and high duty cycle (> 95 %) make it a powerful survey instrument sensitive to pulsar wind nebulae, supernova remnants, active galactic nuclei, and other γ-ray sources. The mechanisms of particle acceleration at these sources can be studied by analyzing their energy spectra. To this end, we have developed an event-by-event energy-reconstruction algorithm employing an artificial neural network to estimate energies of primary γ rays. The Crab Nebula, the brightest source of TeV photons, makes an excellent calibration source for this technique. We will present preliminary results from an analysis of the Crab energy spectrum using this new energy-reconstruction method. This work was supported by the National Science Foundation.