Calcium phosphate granules in the hepatopancreas of the blue crab Callinectes sapidus.

Science.gov (United States)

Becker, G L; Chen, C H; Greenawalt, J W; Lehninger, A L

1974-05-01

The hepatopancreas of the adult male blue crab Callinectes sapidus in intermolt was found to contain substantial amounts of calcium, magnesium, and inorganic phosphorus, averaging about 260, 20, and 250 microg-atoms per g wet tissue, respectively, accounting for over 10% of the tissue dry weight. Electron microscopy of the intact tissue showed three qualitatively different granular structures having electron densities suggestive of high mineral content. After fractionation of the tissue using centrifugal techniques, almost 95% of the total mineral was found to reside in a heavy, nonmitochondrial particulate fraction(s). The bulk of the low-speed pellet consisted of relatively dense, roughly spherical granules 1-5 microm in diameter, which could be considerably purified by repeated suspension in water and low-speed sedimentation. In the electron microscope the isolated granules appeared basically similar to one of the three characteristic types of electron-dense granules seen in the intact tissue. Although the freshly isolated granules lost approximately 50% of their wet weight when dried at 105 degrees C, only 10% more was lost upon dry ashing at 450 degrees C, suggesting a fairly low content of organic material. Chemical analysis revealed calcium, magnesium, and inorganic phosphate at 5.7, 2.1, and 4.4 microg-atoms per mg dried granules, respectively, accounting for 69% of the dry weight of the fraction. By specific enzymatic assays, the freshly isolated granules were found to contain ATP, ADP, and AMP at levels of 0.13, 0.03, and 0.01 micromol/mg, or 8% of their total dry weight. The remainder of the total phosphorus contributed an additional 3%, whereas carbonate, citrate, oxalate, and protein each constituted no more than 1%. The mineral granules of the crab hepatopancreas appear to function as storage forms of calcium and phosphate during the intermolt period. This tissue appears promising as a model for study of the cellular events associated with biological

Population ecology of the blue crab Callinectes danae (Crustacea: Portunidae) in a Brazilian tropical estuary.

Science.gov (United States)

Araújo, Marina S L C; Barreto, Aline V; Negromonte, Aurinete O; Schwamborn, Ralf

2012-03-01

This paper aims at describing the population ecology of the swimming crab Callinectes danae Smith, 1869 in one of the most productive estuaries of Brazil, the Santa Cruz Channel. These crabs were monthly collected from January to December/2009 at four stations along the channel, two in the upper and two in the lower estuary. A total of 2373 specimens of C. danae were collected during the study. Males had a larger average carapace width than non-ovigerous females (60.0 ± 15.6 mm and 52.9 ± 12.4 mm, respectively), an adaptation that gives greater protection for females during the copulation. Overall sex ratio did not differ significantly from 1:1. However, evaluating sex-ratio by sampling area, males and juveniles of both sexes occurred preferentially in the upper estuary (p estuary, an area of major marine influence (p salinity in order to provide a more favorable environment for embryonic and larval development and to enhance larval dispersal. Recruitment of juveniles was continuous along the year, but intensified from March to June and, with less intensity, from October to December.

D1-like dopamine receptors downregulate Na+-K+-ATPase activity and increase cAMP production in the posterior gills of the blue crab Callinectes sapidus.

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Arnaldo, Francis B; Villar, Van Anthony M; Konkalmatt, Prasad R; Owens, Shaun A; Asico, Laureano D; Jones, John E; Yang, Jian; Lovett, Donald L; Armando, Ines; Jose, Pedro A; Concepcion, Gisela P

2014-09-15

Dopamine-mediated regulation of Na(+)-K(+)-ATPase activity in the posterior gills of some crustaceans has been reported to be involved in osmoregulation. The dopamine receptors of invertebrates are classified into three groups based on their structure and pharmacology: D1- and D2-like receptors and a distinct invertebrate receptor subtype (INDR). We tested the hypothesis that a D1-like receptor is expressed in the blue crab Callinectes sapidus and regulates Na(+)-K(+)-ATPase activity. RT-PCR, using degenerate primers, showed the presence of D1βR mRNA in the posterior gill. The blue crab posterior gills showed positive immunostaining for a dopamine D5 receptor (D5R or D1βR) antibody in the basolateral membrane and cytoplasm. Confocal microscopy showed colocalization of Na(+)-K(+)-ATPase and D1βR in the basolateral membrane. To determine the effect of D1-like receptor stimulation on Na(+)-K(+)-ATPase activity, intact crabs acclimated to low salinity for 6 days were given an intracardiac infusion of the D1-like receptor agonist fenoldopam, with or without the D1-like receptor antagonist SCH23390. Fenoldopam increased cAMP production twofold and decreased Na(+)-K(+)-ATPase activity by 50% in the posterior gills. This effect was blocked by coinfusion with SCH23390, which had no effect on Na(+)-K(+)-ATPase activity by itself. Fenoldopam minimally decreased D1βR protein expression (10%) but did not affect Na(+)-K(+)-ATPase α-subunit protein expression. This study shows the presence of functional D1βR in the posterior gills of euryhaline crabs chronically exposed to low salinity and highlights the evolutionarily conserved function of the dopamine receptors on sodium homeostasis. Copyright © 2014 the American Physiological Society.

Concurrent protein synthesis is required for in vivo chitin synthesis in postmolt blue crabs

International Nuclear Information System (INIS)

Horst, M.N.

1990-01-01

Chitin synthesis in crustaceans involves the deposition of a protein-polysaccharide complex at the apical surface of epithelial cells which secrete the cuticle or exoskeleton. The present study involves an examination of in vivo incorporation of radiolabeled amino acids and amino sugars into the cuticle of postmolt blue crabs, Callinectes sapidus. Rates of incorporation of both 3H leucine and 3H threonine were linear with respect to time of incubation. Incorporation of 3H threonine into the endocuticle was inhibited greater than 90% in the presence of the protein synthesis inhibitor, puromycin. Linear incorporation of 14C glucosamine into the cuticle was also demonstrated; a significant improvement of radiolabeling was achieved by using 14C-N-acetylglucosamine as the labeled precursor. Incorporation of 3H-N-acetylglucosamine into the cuticle of postmolt blue crabs was inhibited 89% by puromycin, indicating that concurrent protein synthesis is required for the deposition of chitin in the blue crab. Autoradiographic analysis of control vs. puromycin-treated crabs indicates that puromycin totally blocks labeling of the new endocuticle with 3H glucosamine. These results are consistent with the notion that crustacean chitin is synthesized as a protein-polysaccharide complex. Analysis of the postmolt and intermolt blue crab cuticle indicates that the exoskeleton contains about 60% protein and 40% chitin. The predominant amino acids are arginine, glutamic acid, alanine, aspartic acid, and threonine

The bioeconomic impact of different management regulations on the Chesapeake Bay blue crab fishery

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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.

Ecdysteroids regulate the levels of Molt-Inhibiting Hormone (MIH expression in the blue crab, Callinectes sapidus.

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Sirinart Techa

Full Text Available Arthropod molt is coordinated through the interplay between ecdysteroids and neuropeptide hormones. In crustaceans, changes in the activity of Y-organs during the molt cycle have been regulated by molt-inhibiting hormone (MIH and crustacean hyperglycemic hormone (CHH. Little has been known of the mode of direct effects of ecdysteroids on the levels of MIH and CHH in the eyestalk ganglia during the molt cycle. This study focused on a putative feedback of ecdysteroids on the expression levels of MIH transcripts using in vitro incubation study with ecdysteroids and in vivo RNAi in the blue crab, Callinectes sapidus. Our results show a specific expression of ecdysone receptor (EcR in which EcR1 is the major isoform in eyestalk ganglia. The initial elevation of MIH expression at the early premolt stages is replicated by in vitro incubations of eyestalk ganglia with ecdysteroids that mimic the intrinsic conditions of D0 stage: the concentration (75 ng/ml and composition (ponasterone A and 20-hydroxyecdysone at a 3:1 (w:w ratio. Additionally, multiple injections of EcR1-dsRNA reduce MIH expression by 67%, compared to the controls. Our data provide evidence on a putative feedback mechanism of hormonal regulation during molting cycle, specifically how the molt cycle is repeated during the life cycle of crustaceans. The elevated concentrations of ecdysteroids at early premolt stage may act positively on the levels of MIH expression in the eyestalk ganglia. Subsequently, the increased MIH titers in the hemolymph at postmolt would inhibit the synthesis and release of ecdysteroids by Y-organs, resulting in re-setting the subsequent molt cycle.

Ecdysteroids regulate the levels of Molt-Inhibiting Hormone (MIH) expression in the blue crab, Callinectes sapidus.

Science.gov (United States)

Techa, Sirinart; Chung, J Sook

2015-01-01

Arthropod molt is coordinated through the interplay between ecdysteroids and neuropeptide hormones. In crustaceans, changes in the activity of Y-organs during the molt cycle have been regulated by molt-inhibiting hormone (MIH) and crustacean hyperglycemic hormone (CHH). Little has been known of the mode of direct effects of ecdysteroids on the levels of MIH and CHH in the eyestalk ganglia during the molt cycle. This study focused on a putative feedback of ecdysteroids on the expression levels of MIH transcripts using in vitro incubation study with ecdysteroids and in vivo RNAi in the blue crab, Callinectes sapidus. Our results show a specific expression of ecdysone receptor (EcR) in which EcR1 is the major isoform in eyestalk ganglia. The initial elevation of MIH expression at the early premolt stages is replicated by in vitro incubations of eyestalk ganglia with ecdysteroids that mimic the intrinsic conditions of D0 stage: the concentration (75 ng/ml) and composition (ponasterone A and 20-hydroxyecdysone at a 3:1 (w:w) ratio). Additionally, multiple injections of EcR1-dsRNA reduce MIH expression by 67%, compared to the controls. Our data provide evidence on a putative feedback mechanism of hormonal regulation during molting cycle, specifically how the molt cycle is repeated during the life cycle of crustaceans. The elevated concentrations of ecdysteroids at early premolt stage may act positively on the levels of MIH expression in the eyestalk ganglia. Subsequently, the increased MIH titers in the hemolymph at postmolt would inhibit the synthesis and release of ecdysteroids by Y-organs, resulting in re-setting the subsequent molt cycle.

Population ecology of the blue crab Callinectes danae (Crustacea: Portunidae in a Brazilian tropical estuary

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Marina S.L.C. Araújo

2012-03-01

Full Text Available This paper aims at describing the population ecology of the swimming crab Callinectes danae Smith, 1869 in one of the most productive estuaries of Brazil, the Santa Cruz Channel. These crabs were monthly collected from January to December/2009 at four stations along the channel, two in the upper and two in the lower estuary. A total of 2373 specimens of C. danae were collected during the study. Males had a larger average carapace width than non-ovigerous females (60.0 ± 15.6 mm and 52.9 ± 12.4 mm, respectively, an adaptation that gives greater protection for females during the copulation. Overall sex ratio did not differ significantly from 1:1. However, evaluating sex-ratio by sampling area, males and juveniles of both sexes occurred preferentially in the upper estuary (p O presente trabalho tem por objetivo descrever a estrutura populacional do siri Callinectes danae Smith, 1869 em um dos estuários mais produtivos do Brasil, o Canal de Santa Cruz. As coletas foram realizadas mensalmente de Janeiro a Dezembro/ 2009 em quatro estações ao longo do canal, duas no estuário superior e duas no estuário inferior. Um total de 2373 exemplares de C. danae foi coletado. Os machos apresentaram média de largura de carapaça superior à das fêmeas não-ovígeras (60,0 ± 15,6 mm e 5,9 ± 12,4 mm, respectivamente, uma adaptação que confere maior proteção às fêmeas durante a cópula. A proporção sexual total não diferiu significativamente de 1:1. Porém, avaliando a 'sex-ratio' por área de coleta, os machos e os juvenis residem preferencialmente no estuário superior (p < 0, 05, enquanto as fêmeas adultas e ovígeras habitam no estuário inferior, área de maior influência marinha (p < 0, 05. Enquanto os juvenis procuram águas estuarinas devido a abundância de abrigos e comida, as fêmeas ovígeras migram para áreas de maior profundidade e maior salinidade visando prover um ambiente mais favorável ao desenvolvimento embrionário e

Population biology and distribution of the portunid crab Callinectes ornatus (Decapoda: Brachyura) in an estuary-bay complex of southern Brazil

OpenAIRE

Timoteo T. Watanabe; Bruno S. Sant'Anna; Gustavo Y. Hattori; Fernando J. Zara

2014-01-01

Trawl fisheries are associated with catches of swimming crabs, which are an important economic resource for commercial as well for small-scale fisheries. This study evaluated the population biology and distribution of the swimming crab Callinectes ornatus (Ordway, 1863) in the Estuary-Bay of São Vicente, state of São Paulo, Brazil. Crabs were collected from a shrimp fishing boat equipped with a semi-balloon otter-trawl net, on eight transects (four in the estuary and four in the bay) from Mar...

Population biology and distribution of the portunid crab Callinectes ornatus (Decapoda: Brachyura in an estuary-bay complex of southern Brazil

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Timoteo T. Watanabe

2014-08-01

Full Text Available Trawl fisheries are associated with catches of swimming crabs, which are an important economic resource for commercial as well for small-scale fisheries. This study evaluated the population biology and distribution of the swimming crab Callinectes ornatus (Ordway, 1863 in the Estuary-Bay of São Vicente, state of São Paulo, Brazil. Crabs were collected from a shrimp fishing boat equipped with a semi-balloon otter-trawl net, on eight transects (four in the estuary and four in the bay from March 2007 through February 2008. Specimens caught were identified, sexed and measured. Samples of bottom water were collected and the temperature and salinity measured. A total of 618 crabs were captured (332 males, 267 females and 19 ovigerous females, with a sex ratio close to 1:1. A large number of juveniles were captured (77.67%. Crab spatial distributions were positively correlated with salinity (Rs = 0.73, p = 0.0395 and temperature (Rs = 0.71, p = 0.0092. Two peaks of recruitment occurred, in summer and autumn, and ovigerous females were mostly captured during summer, showing a seasonal reproductive pattern. The results showed that C. ornatus uses the bay as a nursery area for juvenile development. Callinectes ornatus is not yet a legally protected species, and the minimum allowed size of crabs caught in the area, although already restricted, should be carefully evaluated since the removal of large numbers of juveniles could negatively impact the local population.

Seasonal abundance of crustaceans associated with artisanal fishery of blue crab (Callinectes sapidus) in Sisal, Yucatan, Mexico

OpenAIRE

Celis-Sánchez, José Alfredo; Estrella-Canto, Arely de Jesús; Poot-López, Gaspar Román; González-Salas, Carlos; López-Rocha, Jorge Alberto

2014-01-01

Seasonal abundance and selectivity of the main crustacean species associated with blue crab fishing was studied at the port of Sisal, Yucatan, Mexico. For this purpose, 52 crab traps were used, which were divided into four parallel transects placed 100, 150, 200 and 250 m of the shoreline. Each transect consisted of 13 traps 20 m from each other. Traps were set at dusk and checked at dawn, standardizing the fishing effort to 17 hours/trap/day. A total of 832 organisms from eight species were ...

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

Evaluation and management of blue crab Callinectes sapidus (Rathbun, 1896 (Decapoda - Portunidae fishery in the Estuary of Cananéia, Iguape and Ilha Comprida, São Paulo, Brazil

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JT. Mendonça

Full Text Available The Estuary of Cananéia, Iguape and Ilha Comprida is a part of the Estuarine Lagoon System of Cananéia, Iguape and Paranaguá , on the south coast of São Paulo State, Brazil. It has been recognised for its high standards of environmental conservation. The objective of this paper was to assess the blue crab (Callinectes sapidus fishing in the region, from January 1998 to December 2006, and obtain supportive data to implement technical rules for the rational exploitation and resulting conservation of this resource. The results show a remarkable decrease in the fisheries' abundance index (CPUE up to 2005, from 9.4 to 4.0 kg/hour, mainly caused by an increase in fishing effort, from 1,960 to 13,776 hours on a yearly basis. With the decrease in the fishing effort in 2005 and 2006, the abundance index reacted positively, indicating a recovery of the exploited population. Due to the lack of appropriate regulation limiting the fishing effort and organising the fluctuating admission rates of new fishermen, there is a noticeable increase of the effort, above the sustainable level. Therefore, there is a need for measures to limit and control the admission of fishermen in this activity. One of the measures to be considered is the establishment of regular periods where fishing the species is prohibited (called "defeso", each year, especially from September to January. Another measure is to create a fishermen registry and special licenses, to limit the number of new entrants. Such actions require, for their implementation, a co-managed initiative, involving the blue crab fishermen themselves, governmental agencies and resource management researchers, and the integration of ecological, socioeconomic and cultural dimensions.

New functions of arthropod bursicon: inducing deposition and thickening of new cuticle and hemocyte granulation in the blue crab, Callinectes sapidus.

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J Sook Chung

Full Text Available Arthropod growth requires molt-associated changes in softness and stiffness of the cuticle that protects from desiccation, infection and injury. Cuticle hardening in insects depends on the blood-borne hormone, bursicon (Burs, although it has never been determined in hemolymph. Whilst also having Burs, decapod crustaceans reiterate molting many more times during their longer life span and are encased in a calcified exoskeleton, which after molting undergoes similar initial cuticle hardening processes as in insects. We investigated the role of homologous crustacean Burs in cuticular changes and growth in the blue crab, Callinectes sapidus. We found dramatic increases in size and number of Burs cells during development in paired thoracic ganglion complex (TGC neurons with pericardial organs (POs as neurohemal release sites. A skewed expression of Burs β/Burs α mRNA in TGC corresponds to protein contents of identified Burs β homodimer and Burs heterodimer in POs. In hemolymph, Burs is consistently present at ∼21 pM throughout the molt cycle, showing a peak of ∼89 pM at ecdysis. Since initial cuticle hardness determines the degree of molt-associated somatic increment (MSI, we applied recombinant Burs in vitro to cuticle explants of late premolt or early ecdysis. Burs stimulates cuticle thickening and granulation of hemocytes. These findings demonstrate novel cuticle-associated functions of Burs during molting, while the unambiguous and constant presence of Burs in cells and hemolymph throughout the molt cycle and life stages may implicate further functions of its homo- and heterodimer hormone isoforms in immunoprotective defense systems of arthropods.

Extraction and Characterization of Chitin and Chitosan from Blue Crab and Synthesis of Chitosan Cryogel Scaffolds

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Nimet Bölgen

2016-08-01

Full Text Available Polymeric scaffolds produced by cryogelation technique have attracted increasing attention for tissue engineering applications. Cryogelation is a technique which enables to produce interconnected porous matrices from the frozen reaction mixtures of polymers or monomeric precursors. Chitosan is a biocompatible, biodegradable, nontoxic, antibacterial, antioxidant and antifungal natural polymer that is obtained by deacetylation of chitin, which is mostly found in the exoskeleton of many crustacean. In this study, chitin was isolated from the exoskeleton of blue crap (Callinectes sapidus using a chemical method. Callinectes sapidus samples were collected from a market, as a waste material after it has been consumed as food. Demineralization, deproteinization and decolorization steps were applied to the samples to obtain chitin. Chitosan was prepared from isolated chitin by deacetylation at high temperatures. The chemical compositon of crab shell, extracted chitin and chitosan were characterized with FTIR analyses. And also to determine the physicochemical and functional properties of the produced chitosan; solubility, water binding and fat binding analysis were performed. Chitosan cryogel scaffolds were prepared by crosslinking reaction at cryogenic conditions at constant amount of chitosan (1%, w/v with different ratios of glutaraldehyde (1, 3, and 6%, v/v as crosslinker. The chemical structure of the scaffolds were examined by FTIR. Also, the water uptake capacity of scaffolds have been determined. Collectively, the results suggested that the characterized chitosan cryogels can be potential scaffolds to be used in tissue engineering applications.

Atmospheric Correction and Vicarious Calibration of Oceansat-1 Ocean Color Monitor (OCM) Data in Coastal Case 2 Waters

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2012-06-08

uppermost part of the Barataria estuary in southeastern Louisiana (Figure 3). Lac des Allemands is a freshwater lake ( salinity < 1 psu) with a surface...W.; Walker, N.D. Evaluating the potential risk of microcystins to blue crab (Callinectes sapidus) fisheries and human health in a eutrophic estuary ...risk of microcystins to blue crab (Callinectes sapidus) fisheries and human health in a eutrophic estuary . Harmful Algae 2010, 9, 134–143. 5. Ren

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...

The first finding of Ostrea cf. puelchana (Bivalvia living as epibiont on Callinectes exasperates (Decapoda

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Silvio Felipe Barbosa Lima

2017-05-01

Full Text Available This paper describes the epibiosis of Ostrea cf. puelchana on Callinectes exasperatus (Gerstaecker, 1856, both collected from the estuary of the Paraíba River, in the state of Paraíba, northeastern Brazil. The basibiont crab was captured using a trap installed in mangrove area at a depth of about 2 meters. The oyster was closely attached to the left side of dorsal carapace covering most of the epibranchial, mesobranchial and metabranchial regions. Possible advantages and disadvantages for both the epibiont and the basibiont are discussed. We believe that young O. cf. puelchana may avoid a variety of potential predators due to the considerable movement capacity of C. exasperatus and may also serve as a small protective shield for the basibiont. However, the oyster, which is a bivalve with an epifaunal lifestyle, is likely to be negatively affected, mainly due to burrowing activity of the crab. This is the first record of epibiosis between bivalves of the genus Ostrea Linnaeus, 1758 and crabs of the genus Callinectes Stimpson, 1860.

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

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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

Two distinct mtDNA lineages of the blue crab reveal large-scale population structure in its native Atlantic distribution

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Alaniz Rodrigues, Marcos; Dumont, Luiz Felipe Cestari; dos Santos, Cléverson Rannieri Meira; D'Incao, Fernando; Weiss, Steven; Froufe, Elsa

2017-10-01

For the first time, a molecular approach was used to evaluate the phylogenetic structure of the disjunct native American distribution of the blue crab Callinectes sapidus. Population structure was investigated by sequencing 648bp of the Cytochrome oxidase subunit 1 (COI), in a total of 138 sequences stemming from individual samples from both the northern and southern hemispheres of the Western Atlantic distribution of the species. A Bayesian approach was used to construct a phylogenetic tree for all samples, and a 95% confidence parsimony network was created to depict the relationship among haplotypes. Results revealed two highly distinct lineages, one containing all samples from the United States and some from Brazil (lineage 1) and the second restricted to Brazil (lineage 2). In addition, gene flow (at least for females) was detected among estuaries at local scales and there is evidence for shared haplotypes in the south. Furthermore, the findings of this investigation support the contemporary introduction of haplotypes that have apparently spread from the south to the north Atlantic.

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

OpenAIRE

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

2015-01-01

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

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

Science.gov (United States)

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

2018-04-01

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

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.

The Utilization of Blue Swimming Crab (Portunus pelagicus) Waste Product, Lemi, as a Food Flavor

Science.gov (United States)

Sasongko, A. Y.; Dewi, E. N.; Amalia, U.

2018-01-01

Lemi is a wasted product that resulted from the meating process of blue swim crab. One of the utilization of blue swim crab lemi is processed it into a food flavor. The aim of this research was to know the value of glutamic acid in blue swim crab lemi flavor with the addition of dextrin using different concentration and know the level of consumer preference of lemi flavor by using hedonic test. The research was using a Completely Randomized research Design (CRD) with a factor of 0%, 1%, 2%, and 3% dextrin concentration. The treatment that was tested was the additions of 0%, 1%, 2%, and 3% dextrin. The nonparametric data (panelist hedonic level) was analyzed by Kruskal-Wallis and further analysis using Mann-Whitney. The parametric data (glutamic acid content, protein content, moisture content, and solubility level) were analyzed by analysis of varians and further analysis using Honestly Significant Difference. The results showed that flavor with 1% dextrin addition has the highest hedonic score (7,07 swim crab lemi flavor. The flavor resulted from this experiment can be used as an alternative of blue swim crab lemi as processing waste so that it can optimalized any further.

Flood Tide Transport of Blue Crab Postlarvae: Limitations in a Lagoonal Estuary

Science.gov (United States)

Cudaback, C.; Eggleston, D.

2005-05-01

Blue crabs, an important commercial species, spend much of their life in estuaries along the east coast. The larvae spawn at or near the ocean, but the juveniles mature in the lower salinity waters of the estuary. It is generally believed that blue crab postlarvae migrate into near surface waters on flood, possibly cued by increasing salinity, and return to the bottom on ebb. Over several tidal cycles, the postlarvae travel a significant distance up-estuary. This model applies quite well to Chesapeake Bay, which has a strong along-estuary salinity gradient and large tides, but may not apply as well to Pamlico Sound, where circulation and salinity are more wind-driven than tidal. A recently completed study (N. Reyns, PhD), indicates that postlarval blue crabs use flood tides and wind-driven currents to cross Pamlico Sound. This study was based on observations with good spatial coverage, but limited vertical and temporal resolution. We have recently completed a complementary study, sampling crab larvae around the clock at four depths at a single location. Preliminary results from the new study suggest that the crab postlarvae do swim all the way to the surface, on flood only, and that flood currents are strongest slightly below the surface. These observations suggest the utility of flood tide transport in this system. However, near bottom salinity does not seem to be driven by tides; at this point it is unclear what cue might trigger the vertical migration of the postlarvae.

Crecimiento del cangrejo Callinectes danae (Decapoda: Portunidae de la Isla de Margarita, Venezuela

Directory of Open Access Journals (Sweden)

Jesylén Castillo

2011-12-01

Full Text Available Las especies del género Callinectes sostienen pesquerías importantes en varias partes del mundo. En el occidente de Venezuela, Callinectes sapidus es capturado con palangre y sostiene una pesquería artesanal importante en el Lago de Maracaibo; mientras que en la Isla de Margarita, Callinectes danae es capturado con nasa en zonas cercanas a lagunas costeras y su pesca está limitada por la oferta y la demanda. Estos recursos son de considerable importancia económica entre los crustáceos comestibles; sin embargo, pocos estudios han sido reportados sobre la dinámica poblacional y potencialidad pesquera en ambientes costeros de Venezuela que contribuyan a la toma de decisiones en la administración pesquera. En este documento se presenta información de los parámetros de crecimiento del cangrejo Callinectes danae Smith, 1869, con el fin de obtener un conocimiento detallado del patrón de crecimiento y lograr estimaciones más precisas sobre el tamaño de la población y su disponibilidad para la explotación. Se analizó una muestra constituida por 3 623 ejemplares capturados con nasa cangrejera por la flota artesanal, entre octubre 2007 y septiembre 2008. Se estableció la relación longitud-peso y se estimaron los parámetros de crecimiento de las curvas en longitud y peso del modelo de von Bertalanffy. La proporción sexual global mostró que no existe diferencia significativa entre machos y hembras (χ2=0.04, p>0.05. Los valores de las pendientes b entre machos y hembras presentaron diferencias significativas (ts=2.75, pDana Swimming crab growth Callinectes danae (Decapoda: Portunidae from Margarita Island, Venezuela. Callinectes danae is a common species captured with crab traps in nearby areas of coastal lagoons in Margarita Island. Although its considerable economic importance as a fishery resource, few studies have been done on population dynamics and its fishery potential in local coastal environments to support decision making in

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...

Crab Hole Mosquito Blues—The Story

Centers for Disease Control (CDC) Podcasts

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

Responses of free radical metabolism to air exposure or salinity stress, in crabs (Callinectes danae and C. ornatus) with different estuarine distributions.

Science.gov (United States)

Freire, Carolina A; Togni, Valéria G; Hermes-Lima, Marcelo

2011-10-01

The swimming crabs Callinectes danae and C. ornatus are found in bays and estuaries, but C. danae is more abundant in lower salinities, while C. ornatus remains restricted to areas of higher salinity. Experimental crabs of both species were submitted to: air exposure (Ae, 3h), reimmersion in 33‰ (control) sea water (SW) (Ri, 1h) following air exposure; hyposaline (Ho, 10‰ for 2h) or hypersaline (He, 40‰ for 2h) SW, then return to control 33‰ SW (RHo and RHe, for 1h). Hemolymph was sampled for osmolality and chloride determinations. Activity of antioxidant enzymes [glutathione peroxidase (GPX), catalase, glutathione-S-transferase] and levels of carbonyl proteins and lipid peroxidation (TBARS) were evaluated in hepatopancreas, muscle, anterior and posterior gills. In Ho groups, hemolymph concentrations were lower in both species, compared to He groups. C. danae displayed higher control activities of GPX (hepatopancreas and muscle) and catalase (all four tissues) than C. ornatus. C. ornatus presented increased activities of catalase and GPX in Ae, Ri, and He groups. Increased TBARS was seen in C. ornatus tissues (He group). The more euryhaline species displayed higher constitutive activities of antioxidant enzymes, and the less euryhaline species exhibited activation of these enzymes when exposed to air or hyper-salinity. Copyright © 2011 Elsevier Inc. All rights reserved.

K+ and NH4(+) modulate gill (Na+, K+)-ATPase activity in the blue crab, Callinectes ornatus: fine tuning of ammonia excretion.

Science.gov (United States)

Garçon, D P; Masui, D C; Mantelatto, F L M; McNamara, J C; Furriel, R P M; Leone, F A

2007-05-01

To better comprehend the mechanisms of ionic regulation, we investigate the modulation by Na+, K+, NH4(+) and ATP of the (Na+, K+)-ATPase in a microsomal fraction from Callinectes ornatus gills. ATP hydrolysis obeyed Michaelis-Menten kinetics with KM=0.61+/-0.03 mmol L(-1) and maximal rate of V=116.3+/-5.4 U mg(-1). Stimulation by Na+ (V=110.6+/-6.1 U mg(-1); K0.5=6.3+/-0.2 mmol L(-1)), Mg2+ (V=111.0+/-4.7 U mg(-1); K0.5=0.53+/-0.03 mmol L(-1)), NH4(+) (V=173.3+/-6.9 U mg(-1); K0.5=5.4+/-0.2 mmol L(-1)) and K+ (V=116.0+/-4.9 U mg(-1); K0.5=1.5+/-0.1 mmol L(-1)) followed a single saturation curve, although revealing site-site interactions. In the absence of NH4(+), ouabain (K(I)=74.5+/-1.2 micromol L(-1)) and orthovanadate inhibited ATPase activity by up to 87%; the inhibition patterns suggest the presence of F0F1 and K+-ATPases but not Na+-, V- or Ca2+-ATPase as contaminants. (Na+, K+)-ATPase activity was synergistically modulated by K+ and NH4(+). At 10 mmol L(-1) K+, increasing NH4(+) concentrations stimulated maximum activity to V=185.9+/-7.4 U mg(-1). However, at saturating NH4(+) (50 mmol L(-1)), increasing K+ concentrations did not stimulate activity further. Our findings provide evidence that the C. ornatus gill (Na+, K+)-ATPase may be particularly well suited for extremely efficient active NH4(+) excretion. At elevated NH4(+) concentrations, the enzyme is fully active, regardless of hemolymph K+ concentration, and K+ cannot displace NH4(+) from its exclusive binding sites. Further, the binding of NH4(+) to its specific sites induces an increase in enzyme apparent affinity for K+, which may contribute to maintaining K+ transport, assuring that exposure to elevated ammonia concentrations does not lead to a decrease in intracellular potassium levels. This is the first report of modulation by ammonium ions of C. ornatus gill (Na+, K+)-ATPase, and should further our understanding of NH4(+) excretion in benthic crabs.

Abundance, Fishing Season and Management Strategy for Blue Swimming Crab (Portunus pelagicus) in Pangkajene Kepulauan, South Sulawesi, Indonesia.

Science.gov (United States)

Wiyono, Eko Sri; Ihsan

2018-03-01

In order to manage blue swimming crabs in Pangkajene Kepulauan, management measures are required. Since the environment which affects the abundance of the blue swimming crab varies seasonally, it is necessary to take into account the seasonal nature with the aim of developing a management strategy. The objectives of this study are to define the abundance of and fishing season of blue swimming crabs in the Pangkajene Kepulauan waters, South Sulawesi, Indonesia. The fishing season was analysed using seasonal index analysis, while fish abundance was analysed by means of Equilibrium-Schaefer. The result of this study demonstrated that fishermen allocate their fishing gear all year, although the fish catch is seasonal. Based on analysis of the result, the fishing season for the blue swimming crabs is short. The peak fishing season starts in May and finishes in June. However, in order to enable their families to earn a living, fishermen operated their fishing gear throughout the year. As a result, both catch landing and effort were close to maximum sustainable yield (MSY). In order to reduce fishing pressure, it is necessary to reduce fishing gear and have a seasonal arrangement regarding fishing gear allocation.

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,...

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.

Spatial Dynamics of the Blue Crab Spawning Stock in the Gulf of Mexico: Local Processes Driving Regional Patterns.

Science.gov (United States)

Darnell, M. Z.

2016-02-01

Female blue crabs undertake a critical spawning migration seaward, migrating from low-salinity mating habitat to high-salinity waters of the lower estuaries and coastal ocean, where larval survival is highest. This migration occurs primarily through ebb tide transport, driven by an endogenous circatidal rhythm in vertical swimming that is modulated by behavioral responses to environmental cues. Blue crabs are typically considered an estuarine species and fisheries are managed on a state-by-state basis. Yet recent evidence from state and regional fishery independent survey programs suggests that the spawning migration can take females substantial distances offshore (>150 km), and that offshore waters are important spawning grounds for female blue crabs in the Gulf of Mexico. This is especially true in areas where freshwater inflow is high, resulting in low estuarine and coastal salinities. In low-salinity, high-inflow areas (e.g., Louisiana), spawning occurs further offshore while in high-salinity, low-inflow areas (e.g., South Texas), spawning takes place primarily within the estuary. Regional patterns in spawning locations both inshore and offshore are driven by interactions between behavioral mechanisms and local oceanographic conditions during the spawning migration. These environmentally driven differences in spawning locations have implications for larval survival and population connectivity, and emphasize the need for interjurisdictional assessment and management of the blue crab spawning stock.

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…

Biological studies on the blue crab Portunus pelagicus and its parasitic infection in Kuwaiti waters.

Science.gov (United States)

Al-Behbehani, Bahija E

2007-04-01

The study investigated the parasites of symbiotic fauna of the blue crab, Portunus pelagicus and the environmental factors, which was lacking in Kuwait. P. pelagicus feeding habits was studied by examination of the digestive tract. The foregut (stomach) contents of 250 crabs (110 male & 140 female) collected from fish-market, Souq-Sharq, Edelyia capital governorate were investigated. A barnacle, Balanus sp. and staked barnacle Octolasmis sp. (Crustacea: Cirripedia) were found strongly firmly to the carapace, appendages and gills of 30% male crabs and 27% female ones. Endoparasites included unidentified immature trematode stages and nematode larvae in the muscular tissues of both sexes. The main food recovered included molluscs, crustaceans, fish bones and unidentified food materials. The results were reported, photographed and critically discussed.

Dine or dash? Turbulence inhibits blue crab navigation in attractive-aversive odor plumes by altering signal structure encoded by the olfactory pathway.

Science.gov (United States)

Weissburg, Marc; Atkins, Lorin; Berkenkamp, Kimberly; Mankin, Danielle

2012-12-01

Blue crabs can distinguish and navigate to attractive (food) odors even when aversive odors (injured crab metabolites) are released nearby. Blue crabs in these conditions detect the aversive odor and avoid it, but find the attractive source with nearly the same success rate as when the attractive source is presented alone. Spatially and temporally distinct odor filaments appear to signal to foragers that the two odor sources are not co-located, and hence navigating to the attractive odor entails an acceptable risk of predation. However, environmentally produced turbulence suppresses tracking by homogenizing the two odors; blue crabs fail to track to the attractive source when the aversive source is present, even though turbulence does not substantially inhibit tracking to the attractive source alone. Removal of sensory input from aesthetascs on the antennules, but not chemosensors on the legs, rescues navigation to attractive-aversive dual plumes in turbulent conditions. These results suggest that mixing in the natural environment may amplify the effects of predators by suppressing tracking to food odors when aversive cues are present, and that the olfactory pathway mediates the response.

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.

Development Of Enzyme Digestive Activity Of Blue Crab Portunus Pelagicus Larvae

OpenAIRE

Nikhlani, Andi; Sukarti, Komsanah

2017-01-01

Seed production continuity of Portunus pelagicus larvae had been conducted but the results were still un-consistent Digestive activity was known to be associated with the type of feed consumed by larvae. Amylase, lipase, and trypsin enzymes were used as a biological indicators to measure the digestion of feed. The aim of this study was to describe the activity of digestive enzymes in blue swimming crab larvae. Digestive enzyme activity data obtained was presented in graphical form and anal...

[Temporal and spatial distribution of the crab Callinectes sapidus (Decapoda: Portunidae) in Chetumal Bay, Quintana Roo, Mexico].

Science.gov (United States)

Ortiz-León, Héctor J; Jesús-Navarrete, Alberto de; Cordero, Eloy Sosa

2007-03-01

In order to determine temporal and spatial distribution patterns of Callinectes sapidus, samplings were carried out during the cold-front (January-February), dry (May-June) and rainy (August-September, 2002) climatic seasons, in 30 sampling stations of Chetumal Bay, grouped in sectors A (14 stations), B (eight stations) and C (eight stations). In each sampling station crabs were collected from two transects parallel to the coast, each with three traps, separated by 30 m. Sediments were calcareous coarse and medium sand, white or lightly gray. A total of 1 031 specimens were collected. CPEU (Capture Per Effort Unit) differed spatially and temporally. Highest CPEU was found in sector C with 1.3 ind.trap(-1), and in the rainy season with 1.1 ind.trap(-1). Population was predominantly composed of male individuals. The male:female ratio was 15:1. Males and adults (group II) CPEU was significant different between sectors and climatic seasons. Both males and adults (group II) had a greater CPEU in sector C (1.2 ind.trap-) and in the rainy season (1.1 ind.trap(-1)). Abundance of female and juvenile individuals (group I) was low during the sampling period whereas group 0 juvenile individuals were not found. A greater relative frequency between sectors and climatic seasons were observed in 130-139 mm and 140-149 mm size interval (CW). C. sapidus occurred on sandy sediments in Chetumal Bay. Pearson product moment correlations exhibited significant relationships between CPEU and temperature, salinity and dissolved oxygen. In Chetumal Bay, the spatial and temporal distribution of C. sapidus can be related to salinity, temperature, habitat quality, food availability, recruitment and reproduction events of individuals.

Biodiversidad, morfometría y alimentación de los cangrejos del género Callinectes (Decapoda: Portunidae en Santiago de Cuba

Directory of Open Access Journals (Sweden)

Liliana Gómez Luna

2009-09-01

Full Text Available El objetivo del presente trabajo es el estudio del género Callinectes en la zona costera del municipio de Santiago de Cuba. Se realizó una recolecta de 257 ejemplares durante marzo de 2007 a abril de 2008, en ocho estaciones a lo largo de la costa. El género resultó estar ampliamente distribuido en el litoral y representado al menos por cuatro especies: C. sapidus, C. similis, C. rathbunae y C. larvatus, las dos últimas no incluidas en la lista publicada de crustáceos (Crustacea: Decapoda cubanos. Las especies más abundantes resultaron ser C. sapidus y C. similis. C. rathbunae fue la más ampliamente distribuida. El análisis del contenido estomacal permitió identificar nueve categorías alimentarias, siendo las más importantes los peces y las macroalgas. Las especies de Callinectes tienen un amplio espectro trófico; comen no sólo lo disponible, sino también lo más abundante.Biodiversity, morphometry and diet of Callinectes crabs (Decapoda: Portunidae in Santiago de Cuba. On the basis of fishery intensity and proximity to river mouth, a total of 257 swimming Callinectes crabs were collected from March 2007 to April 2008 in eight localities. Captures were made with hanging nets, to a maximal depth of 1.5m, establishing a top time of 2 hr. The genus was widely distributed, and it is represented at least by four species: C. sapidus, C. similis, C. rathbunae and C. larvatus, the last two not included in the last list of Cuban crustaceans (Crustacea: Decapoda. The size and shape of the gonopods were very useful as taxonomical criteria, considering the prevalence of males. The most abundant species were C. sapidus (47.08%, and C. similis (30.35%. C. rathbunae, which was identified at 75% (6 of the localities, showed a better distribution, followed by C. sapidus, which appears in the 63% (5. Sex rate (Rs by species (male:female was 6.20 for C. rathbunae, 3.58 for C. similis, 1.40 for C. larvatus and 0.40 for C. sapidus. The most abundant

The Effects of Ocean Acidification on Predator-Prey Interactions between Mya arenaria and Callinectes sapidus

Science.gov (United States)

Longmire, K.; Glaspie, C.; Seitz, R.

2016-02-01

The study examined the implications of ocean acidification for Mya arenaria and the predator-prey dynamics between M. arenaria and Callinectes sapidus. Clams were subjected to either ambient conditions or acidified conditions and grown over four weeks. Mortality, shell lengths, and biomass (ash-free dry weights) were recorded for clams destructively sampled each week. Clams were subjected to behavioral experiments to determine their response to an approaching physical disturbance. Crabs were exposed to acidified or ambient conditions for 48 hours, and placed in 48 hour mesocosm trials with clams. Shell lengths, mortality and biomass between the ambient and acidified clams were not significantly different between acidified and ambient treatments. Shell ash weights were lower for acidified clams, evidence of shell dissolution. In the behavioral experiment, ocean acidification reduced the ability of clams to respond to a predator stimulus. Lastly, in predator-prey mesocosm trials, in ambient conditions, crabs ate all or none of the available clams, whereas acidified crabs ate all available clams in many trials and ate at least one acidified clam per trial. The early effects of ocean acidification on M. arenaria will manifest in trophic interactions with other species, rather than impacting M. arenaria alone.

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.

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...

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.

The spatial and temporal patterns of odors sampled by lobsters and crabs in a turbulent plume.

Science.gov (United States)

Reidenbach, Matthew A; Koehl, M A R

2011-09-15

Odors are dispersed across aquatic habitats by turbulent water flow as filamentous, intermittent plumes. Many crustaceans sniff (take discrete samples of ambient water and the odors it carries) by flicking their olfactory antennules. We used planar laser-induced fluorescence to investigate how flicking antennules of different morphologies (long antennules of spiny lobsters, Panulirus argus; short antennules of blue crabs, Callinectes sapidus) sample fluctuating odor signals at different positions in a turbulent odor plume in a flume to determine whether the patterns of concentrations captured can provide information about an animal's position relative to the odor source. Lobster antennules intercept odors during a greater percentage of flicks and encounter higher peak concentrations than do crab antennules, but because crabs flick at higher frequency, the duration of odor-free gaps between encountered odor pulses is similar. For flicking antennules there were longer time gaps between odor encounters as the downstream distance to the odor source decreases, but shorter gaps along the plume centerline than near the edge. In contrast to the case for antennule flicking, almost all odor-free gaps were <500 ms at all positions in the plume if concentration was measured continuously at the same height as the antennules. Variance in concentration is lower and mean concentration is greater near the substratum, where leg chemosensors continuously sample the plume, than in the water where antennules sniff. Concentrations sampled by legs increase as an animal nears an odor source, but decrease for antennules. Both legs and antennules encounter higher concentrations near the centerline than at the edge of the plume.

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...

AFSC/RACE/SAP/Daly: Juvenile red and blue king crab prey preference 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 ratios of prey species (year-0 blue and red king crabs) and habitat type (shell and...

Induced thermal stress on serotonin levels in the blue swimmer crab, Portunus pelagicus

Directory of Open Access Journals (Sweden)

Saravanan Rajendiran

2016-03-01

Full Text Available The temperature of habitat water has a drastic influence on the behavioral, physiological and biochemical mechanisms of crustaceans. Hyperglycemia is a typical response of many aquatic animals to harmful physical and chemical environmental changes. In crustaceans increased circulating crustacean hyperglycemic hormone (CHH and hyperglycemia are reported to occur following exposure to several environmental stress. The biogenic amine, serotonin has been found to modulate the CHH levels and oxidation of serotonin into its metabolites is catalysed by monoamine oxidase. The blue swimmer crab, Portunus pelagicus is a dominant intertidal species utilized throughout the indo-pacific region and is a particularly important species of Palk bay. It has high nutritional value and delicious taste and hence their requirements of capture and cultivation of this species are constantly increasing. This species experiences varying and increasing temperature levels as it resides in an higher intertidal zone of Thondi coast. The present study examines the effect of thermal stress on the levels of serotonin and crustacean hyperglycemic hormone in the hemolymph of P. pelagicus and analyzes the effect of the monoamine oxidase inhibitor, pargyline on serotonin and CHH level after thermal stress. The results showed increased levels of glucose, CHH and serotonin on exposure to 26 °C in control animals. Pargyline injected crabs showed highly significant increase in the levels of CHH and serotonin on every 2 °C increase or decrease in temperature. A greater CHH level of 268.86±2.87 fmol/ml and a greater serotonin level of 177.69±10.10 ng/ml was observed at 24 °C. This could be due to the effect of in maintaining the level of serotonin in the hemolymph and preventing its oxidation, which in turn induces hyperglycemia by releasing CHH into hemolymph. Thus, the study demonstrates the effect of thermal stress on the hemolymph metabolites studied and the role of

Induced thermal stress on serotonin levels in the blue swimmer crab, Portunus pelagicus.

Science.gov (United States)

Rajendiran, Saravanan; Muhammad Iqbal, Beema Mahin; Vasudevan, Sugumar

2016-03-01

The temperature of habitat water has a drastic influence on the behavioral, physiological and biochemical mechanisms of crustaceans. Hyperglycemia is a typical response of many aquatic animals to harmful physical and chemical environmental changes. In crustaceans increased circulating crustacean hyperglycemic hormone (CHH) and hyperglycemia are reported to occur following exposure to several environmental stress. The biogenic amine, serotonin has been found to modulate the CHH levels and oxidation of serotonin into its metabolites is catalysed by monoamine oxidase. The blue swimmer crab, Portunus pelagicus is a dominant intertidal species utilized throughout the indo-pacific region and is a particularly important species of Palk bay. It has high nutritional value and delicious taste and hence their requirements of capture and cultivation of this species are constantly increasing. This species experiences varying and increasing temperature levels as it resides in an higher intertidal zone of Thondi coast. The present study examines the effect of thermal stress on the levels of serotonin and crustacean hyperglycemic hormone in the hemolymph of P. pelagicus and analyzes the effect of the monoamine oxidase inhibitor, pargyline on serotonin and CHH level after thermal stress. The results showed increased levels of glucose, CHH and serotonin on exposure to 26 °C in control animals. Pargyline injected crabs showed highly significant increase in the levels of CHH and serotonin on every 2 °C increase or decrease in temperature. A greater CHH level of 268.86±2.87 fmol/ml and a greater serotonin level of 177.69±10.10 ng/ml was observed at 24 °C. This could be due to the effect of in maintaining the level of serotonin in the hemolymph and preventing its oxidation, which in turn induces hyperglycemia by releasing CHH into hemolymph. Thus, the study demonstrates the effect of thermal stress on the hemolymph metabolites studied and the role of pargyline in elevating the

Comparação do crescimento entre Callinectes sapidus (Crustacea, Decapoda, Portunidae coletados em campo e mantidos em condições contoladas Growth comparison between Callinectes sapidus (Crustacea, Decapoda, Portunidae collected on the field and maintained under controlled conditions

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Marcos A. Rodrigues

2008-09-01

Full Text Available Devido à falta de estruturas rígidas para determinação de idade em crustáceos, métodos que se baseiam na determinação de idade através da distribuição da freqüência de comprimentos são comumente utilizados. Neste trabalho, foi comparado o crescimento do siri-azul, Callinectes sapidus Rathbun, 1896, em laboratório e a partir de indivíduos de campo. Os indivíduos de laboratório, após a coleta, tiveram seu crescimento acompanhado individualmente. A temperatura foi mantida constante (25±2°C e a salinidade a 20±5. Os indivíduos do campo foram coletados entre 2002 e 2004 em pontos pré-determinados no estuário da Laguna dos Patos, com rede de portas. A biometria, nos dois casos, constou da medida da largura da carapaça (LC mm. As estimativas das curvas de crescimento, segundo o modelo de Bertalanffy para os indivíduos de campo, foram obtidas pelo acompanhamento do deslocamento modal (MPA. O tamanho máximo de largura de carapaça utilizado foi mantido fixo em todas as análises (157,78 mm para fêmeas e 162,71 mm para machos. Para os indivíduos mantidos em laboratório, os parâmetros e a longevidade obtidos foram k=0,001/dia; t o=-1,53; longevidade de 3117 dias (8,5 anos para machos e k=0,002/dia; t o=-29,5; longevidade de 2795 dias para fêmeas (7,7 anos. Os parâmetros de crescimento e a longevidade estimados para os animais coletados em campo foram k=0,004/dia; t o=-4,23; 1267 dias (3,5 anos para machos e k=0,004/dia; t o=-3,71; 1260 dias (3,45 anos para fêmeas. Foram encontradas diferenças significativas entre animais de laboratório e de campo, sugerindo que a espécie responde de forma diferente ao ambiente em que está inserida.The absence of hard structures which register age on crustaceans requires the use of length-based methods for age determination, and modal progression analysis (MPA to estimate growth. In this paper, individual growth of the blue crab Callinectes sapidus Rathbun, 1896 was studied in the

The Crab Boat Engineering Design Challenge

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Love, Tyler S.; Ryan, Larry

2017-01-01

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

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

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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.

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

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Spivak, Eduardo D.

2010-09-01

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

The assemblage composition and structure of swimming crabs (Portunoidea) in continental shelf waters of southeastern Brazil

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Andrade, L. S.; Frameschi, I. F.; Costa, R. C.; Castilho, A. L.; Fransozo, A.

2015-02-01

Three regions along the Brazilian coast characterized by the occurrence of contrasting natural phenomena, such as upwellings and continental input, were surveyed to determine the composition and structure of the assemblage of swimming crabs. Twelve monthly collections were undertaken (July 2010 to June 2011) in Macaé, Rio de Janeiro (MAC); Ubatuba, São Paulo (UBA); and São Francisco do Sul, Santa Catarina (SFS). The lowest values ​​of the phi sediment grain size measure, bottom temperature and the highest values of organic matter and salinity were measured in MAC. In all, 10,686 individuals were collected, belonging to six species of Portunoidea: Arenaeus cribrarius, Callinectes danae, Callinectes ornatus, Callinectes sapidus, Achelous spinicarpus and Achelous spinimanus. A Multiple Response Permutation Procedure (MRPP) test indicated that the species composition differed significantly among the sampling sites, showing substantial heterogeneity in the composition and abundance of species among regions. The results suggest that C. danae was more abundant in waters with lower salinity and lower organic matter content. In contrast, A. spinimanus is positively correlated with these factors, showing a greater abundance under the opposite conditions. Callinectes ornatus appeared not to show strong selectivity for particular habitat characteristics. We conclude from these findings that areas affected by different phenomena produce changes in the composition and abundance of the assemblage of Portunoidea. Although the strength of eutrophication differs between UBA and MAC, the substantial continental inflow affecting SFS favors the development of species that complete their life cycle in the estuary.

A Stock Assessment of the Blue Swimming Crab Portunus pelagicus (Linnaeus, 1758) for Sustainable Management in Kung Krabaen Bay, Gulf of Thailand.

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Kunsook, Chutapa; Gajaseni, Nantana; Paphavasit, Nittharatana

2014-08-01

A stock assessment of blue swimming crabs, Portunus pelagicus was conducted with crab gill nets and collapsible crab traps at Kung Krabaen Bay, in the eastern Gulf of Thailand, from 2008 to 2009. Several key indicators show that P. pelagicus population is in crisis. Fishing mortality shows an increase to 4.14. The exploitation rate is 0.71, higher than the optimal value of 0.38. The size of the mature females has also decreased from 8.10±0.39 cm to 7.52±1.14 cm. The average fecundity is 0.572×10(6)±0.261×10(6) eggs per batch, and the sex ratio (male:female) is 1:0.92. Based on these results, a sustainable management program for P. pelagicus was proposed as follows: (i) closing the bay during the spawning season, (ii) restoration of the Enhalus acoroides seagrass beds, (iii) restocking crab larvae in the bay and (iv) educating and networking all stakeholders to develop a better understanding of the ecology of the crab to support sustainable fishery management in Kung Krabaen Bay.

Estrutura populacional de Callinectes ornatus Ordway (Crustacea, Portunidae no Balneário Shangri-Lá, Pontal do Paraná, Paraná, Brasil

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Baptista Cassiana

2003-01-01

Full Text Available Swimming crabs are commonly found in the otter-trawl shrimp fishery by-catch, which operate intensively in the Coastal Plain of Leste Beach, where is located Shangri-lá Beach (25°37'30"S and 48°25'08"W, Paraná State. This work aimed to study the population structure of Callinectes ornatus Ordway, 1863, the most abundant swimming crab in this beach. Between March 2000 and April 2001, fortnightly visits were accomplished in Shangri-lá at the fish market, where all swimming crabs of one otter-trawl were collected. The following data from each individual of C. ornatus were obtained: sex, carapace width (excluding lateral spines, weight, and the gonadal maturation stage, based on its color and size. Juveniles and mature males were dominant, mean sexual proportion was 2.2:1 (males:females. Two recruitment periods were detected, but few ovigerous females were obtained. Size at sexual maturation was estimated at 55mm for males, and 48 mm for females. Both sexes presented positives allometric growths. The results indicate that an important portion of C. ornatus population is captured in the otter-trawl shrimp fishery in Shangri-lá Beach (Paraná. Such information is important for futures plans of by-catch management in that area.

Transport of Blue Crab Larvae in the Northern Gulf of Mexico During the Deepwater Horizon Oil Spill

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2015-05-11

the Deepwater Horizon (DWH) oil spill. The DWH spill, the largest accidental marine oil spill in US history (Graham et al. 2011), started when the...DWH oil platform, situ- ated 80 km southeast of Venice , Louisiana, ex- ploded and sank on 20 April 2010. An estimated 4.0 million barrels of oil...al. (1980). Using this ffiM together with spawning and larval behavior parameters from the known natural history of blue crabs, we ran 24

Assessment of heavy metal concentrations in water, sediment and biota (fish and crabs) samples from the Densu Delta

International Nuclear Information System (INIS)

Kudu, I.B.

2010-01-01

The aim of the study was assess the concentration of some selected heavy metals in water, sediments and biota (fish and crab) sampled from the Densu Delta. In situ and laboratory based analysis were carried out to measure the following physicochemical properties of surface water from the delta; temperature, pH, electrical conductivity (EC), salinity, total dissolved solids (TDS), alkalinity, sodium ion concentration (Na+), potassium ion concentration (K+), chloride ion concentration (Cl), bicarbonate concentration, phosphate concentration, nitrate concentration, sulphate concentration and biochemical oxygen demand (BOD). Heavy metal (Fe, Zn, Cu, Ni, Cd, Cr, Pb and Hg) concentrations in water, sediments, fish and crab sampled at six sites from the Densu Delta wetland in the month of December, 2009 were analysed using VARIAN Fast Sequential Atomic Absorption Spectrophotometer (AAS) model AA240 FS. Two fish species; Blackchin tilapia (Sarotherodon melanotheron), White mullet (Mugil curema) and one species of crab; Blue swimming crab (Callinectes amnicola) were collected from the Densu Delta wetland and analysed. Heavy metal contents in the fish were higher in gill tissue than muscle tissue while in crabs concentrations were higher in the soft tissue than the shell. Levels of Fe, Zn and Cu in the muscle tissue of S. melanotheron were greater than the levels detected in the muscle tissue of M. curema. Cd, Ni and Hg were detected in gill tissue but not in the muscle tissue of S. melanotheron, M. curema on the other hand contained these metals in both gill and muscle tissue. The maximum level of Fe (34.98 mg/L), Zn (25.08 mg/L) in the muscle of S. melanotheron was observed at Bortianor and Zn (2.70 mg/L) was observed at Tetegu. In the M. curema, the maximum level of Fe (34.66 mg/L), Zn (15.9 mg/L) and Cu (1.43 mg/L) was detected at Aplaku, Tetegu and Faana respectively. Heavy metal concentrations were higher in sediment than water. The presence of elevated levels of Cd

A sex-specific metabolite identified in a marine invertebrate utilizing phosphorus-31 nuclear magnetic resonance.

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Robert A Kleps

Full Text Available Hormone level differences are generally accepted as the primary cause for sexual dimorphism in animal and human development. Levels of low molecular weight metabolites also differ between men and women in circulating amino acids, lipids and carbohydrates and within brain tissue. While investigating the metabolism of blue crab tissues using Phosphorus-31 Nuclear Magnetic Resonance, we discovered that only the male blue crab (Callinectes sapidus contained a phosphorus compound with a chemical shift well separated from the expected phosphate compounds. Spectra obtained from male gills were readily differentiated from female gill spectra. Analysis from six years of data from male and female crabs documented that the sex-specificity of this metabolite was normal for this species. Microscopic analysis of male and female gills found no differences in their gill anatomy or the presence of parasites or bacteria that might produce this phosphorus compound. Analysis of a rare gynandromorph blue crab (laterally, half male and half female proved that this sex-specificity was an intrinsic biochemical process and was not caused by any variations in the diet or habitat of male versus female crabs. The existence of a sex-specific metabolite is a previously unrecognized, but potentially significant biochemical phenomenon. An entire enzyme system has been synthesized and activated only in one sex. Unless blue crabs are a unique species, sex-specific metabolites are likely to be present in other animals. Would the presence or absence of a sex-specific metabolite affect an animal's development, anatomy and biochemistry?

Disease ecology of Hematodinium perezi in a high salinity estuary: investigating seasonal trends in environmental detection.

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Lycett, K A; Pitula, J S

2017-05-11

The blue crab Callinectes sapidus has seen a general decline in population levels. One factor influencing mortality is infections by Hematodinium perezi, a dinoflagellate parasite. A 2 yr study was conducted in 2014 and 2015 to monitor H. perezi DNA within the Maryland (USA) coastal bays, comparing seasonal cycles in the abundance of parasite DNA in environmental samples to parasite presence in host blue crabs. A late summer to early fall peak in H. perezi infections in blue crabs was observed, consistent with previous work. Infection intensities matched this trend, showing a slow progression of low intensity infections early in the year, with a peak in moderate and heavy infections occurring between July and September, for both years. It was hypothesized that the peak in water column occurrence would coincide with those months when infection intensities were highest in blue crabs. As the peaks in water column occurrence were in July 2014 and August-September 2015, this is consistent with sporulation being the primary contributor to environmental detection in summer months. An additional peak in environmental detection occurred in both years during the early spring months, the cause of which is currently unknown but may be related to infections in overwintering crabs or alternate hosts. Several new crustacean hosts were identified within this estuary, including grass shrimp Palaemonetes spp. and the sand shrimp Crangon septemspinosa, as well as the mud crab Dyspanopeus sayi. Improved knowledge of this disease system will allow for better management of this important fishery.

Effects of gamma irradiation on the physical and sensory quality and inactivation of Listeria monocytogenes in blue swimming crab meat (Portunas pelagicus)

International Nuclear Information System (INIS)

Suklim, Kannapha; Flick, George J.; Vichitphan, Kanit

2014-01-01

Blue swimming crab lump (backfin) meat were exposed to 2, 4, and 6 kGy doses of Co 60 irradiation and evaluated for changes in physical, sensory properties, and Listeria monocytogenes inactivation. Irradiation up to 6 kGy resulted in no textural changes (p>0.05) in maximum shear forces; however, these exposures resulted in sensory quality changes (p<0.05) as determined by a triangle overall difference test (n=50) at each irradiation level. Irradiation had no effect (p>0.05) on L ⁎ color value. Irradiation at 4 and 6 kGy resulted in listericidal reductions greater than 6.65 (Department of Medical Science, Ministry of Health, Thailand, [DMST] 1783) and 7.56 logs (DMST 4553). Irradiation doses of 1 and 2 kGy resulted in a reduction of 2.10 and 5.35 logs respectively of L. monocytogenes DMST 1783 and 1.56 and 4.19 logs respectively of L. monocytogenes DMST 4553. The D 10 values of L. monocytogenes DMST 1783 and 4553 were 0.35 and 0.45 kGy. The study indicated that low-dose gamma irradiation would increase the safety of blue swimming crab meat without unacceptable changes in texture and L ⁎ color value. - Highlights: • γ-irradiation up to 6 kGy caused no changes in fresh crab meat textural properties. • γ-irradiation increased safety of ready-to-eat product i.e. fresh crab meat. • γ-irradiation had either listericidal or listeristatic effect on L. monocytogenes. • L. monocytogenes were completely inactivated by 4 kGy and 6 kGy γ-irradiation. • 1–2 kGy lethally injured L. monocytogenes but survivors increased during storage

Histological organization of the central nervous system and distribution of a gonadotropin-releasing hormone-like peptide in the blue crab, Portunus pelagicus.

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Saetan, Jirawat; Senarai, Thanyaporn; Tamtin, Montakan; Weerachatyanukul, Wattana; Chavadej, Jittipan; Hanna, Peter J; Parhar, Ishwar; Sobhon, Prasert; Sretarugsa, Prapee

2013-09-01

We present a detailed histological description of the central nervous system (CNS: brain, subesophageal ganglion, thoracic ganglia, abdominal ganglia) of the blue crab, Portunus pelagicus. Because the presence of gonadotropin-releasing hormone (GnRH) in crustaceans has been disputed, we examine the presence and localization of a GnRH-like peptide in the CNS of the blue crab by using antibodies against lamprey GnRH (lGnRH)-III, octopus GnRH (octGnRH) and tunicate GnRH (tGnRH)-I. These antibodies showed no cross-reactivity with red-pigment-concentrating hormone, adipokinetic hormone, or corazonin. In the brain, strong lGnRH-III immunoreactivity (-ir) was detected in small (7-17 μm diameter) neurons of clusters 8, 9 and 10, in medium-sized (21-36 μm diameter) neurons of clusters 6, 7 and 11 and in the anterior and posterior median protocerebral neuropils, olfactory neuropil, median and lateral antenna I neuropils, tegumentary neuropil and antenna II neuropil. In the subesophageal ganglion, lGnRH-III-ir was detected in medium-sized neurons and in the subesophageal neuropil. In the thoracic and abdominal ganglia, lGnRH-III-ir was detected in medium-sized and small neurons and in the neuropils. OctGnRH-ir was observed in neurons of the same clusters with moderate staining, particularly in the deutocerebrum, whereas tGnRH-I-ir was only detected in medium-sized neurons of cluster 11 in the brain. Thus, anti-lGnRH-III shows greater immunoreactivity in the crab CNS than anti-octGnRH and anti-tGnRH-I. Moreover, our functional bioassay demonstrates that only lGnRH-III has significant stimulatory effects on ovarian growth and maturation. We therefore conclude that, although the true identity of the crab GnRH eludes us, crabs possess a putative GnRH hormone similar to lGnRH-III. The identification and characterization of this molecule is part of our ongoing research.

Accumulation of organic and inorganic contaminants in shellfish collected in estuarine waters near Pensacola, Florida: Contamination profiles and risks to human consumers

International Nuclear Information System (INIS)

Karouna-Renier, Natalie K.; Snyder, Richard A.; Allison, Jeffrey G.; Wagner, Matthew G.; Ranga Rao, K.

2007-01-01

We conducted a screening level assessment of contaminants in blue crabs (Callinectes sapidus) and oysters (Crassostrea virginica) from bays and bayous in the Pensacola, FL area. Tissue samples were analyzed for 17 dioxins/furans, 12 dioxin-like PCB (DL-PCBs) congeners, mercury, and various metals. Contaminant levels were compared to screening values (SV) calculated using U.S. EPA recommendations for establishing consumption advisories. All sampling locations exceeded the SV (0.098 pg g -1 ) for dioxins/furans/DL-PCBs, based on a Florida-specific consumption rate (46 g day -1 ). Arsenic (inorganic), mercury, cadmium, and zinc levels exceeded SVs in samples from select locations, and with the exception of mercury, these locations were generally downstream of known contaminated areas. We also assessed potential human health risks from consumption of these species. Risks to human health were greatest from consumption of crab hepatopancreas, suggesting that consumption of hepatopancreas, whether directly or indirectly, from crabs collected anywhere in the Pensacola Bay region should be avoided. - Elevated levels of dioxins/furans and dioxin-like PCBs were detected in blue crabs and oysters from select locations in the Pensacola Bay region

Turbidity interferes with foraging success of visual but not chemosensory predators.

Science.gov (United States)

Lunt, Jessica; Smee, Delbert L

2015-01-01

Predation can significantly affect prey populations and communities, but predator effects can be attenuated when abiotic conditions interfere with foraging activities. In estuarine communities, turbidity can affect species richness and abundance and is changing in many areas because of coastal development. Many fish species are less efficient foragers in turbid waters, and previous research revealed that in elevated turbidity, fish are less abundant whereas crabs and shrimp are more abundant. We hypothesized that turbidity altered predatory interactions in estuaries by interfering with visually-foraging predators and prey but not with organisms relying on chemoreception. We measured the effects of turbidity on the predation rates of two model predators: a visual predator (pinfish, Lagodon rhomboides) and a chemosensory predator (blue crabs, Callinectes sapidus) in clear and turbid water (0 and ∼100 nephelometric turbidity units). Feeding assays were conducted with two prey items, mud crabs (Panopeus spp.) that rely heavily on chemoreception to detect predators, and brown shrimp (Farfantepenaus aztecus) that use both chemical and visual cues for predator detection. Because turbidity reduced pinfish foraging on both mud crabs and shrimp, the changes in predation rates are likely driven by turbidity attenuating fish foraging ability and not by affecting prey vulnerability to fish consumers. Blue crab foraging was unaffected by turbidity, and blue crabs were able to successfully consume nearly all mud crab and shrimp prey. Turbidity can influence predator-prey interactions by reducing the feeding efficiency of visual predators, providing a competitive advantage to chemosensory predators, and altering top-down control in food webs.

Effects of gamma irradiation on the physical and sensory quality and inactivation of Listeria monocytogenes in blue swimming crab meat (Portunas pelagicus)

Science.gov (United States)

Suklim, Kannapha; Flick, George J.; Vichitphan, Kanit

2014-10-01

Blue swimming crab lump (backfin) meat were exposed to 2, 4, and 6 kGy doses of Co60 irradiation and evaluated for changes in physical, sensory properties, and Listeria monocytogenes inactivation. Irradiation up to 6 kGy resulted in no textural changes (p>0.05) in maximum shear forces; however, these exposures resulted in sensory quality changes (p0.05) on L* color value. Irradiation at 4 and 6 kGy resulted in listericidal reductions greater than 6.65 (Department of Medical Science, Ministry of Health, Thailand, [DMST] 1783) and 7.56 logs (DMST 4553). Irradiation doses of 1 and 2 kGy resulted in a reduction of 2.10 and 5.35 logs respectively of L. monocytogenes DMST 1783 and 1.56 and 4.19 logs respectively of L. monocytogenes DMST 4553. The D10 values of L. monocytogenes DMST 1783 and 4553 were 0.35 and 0.45 kGy. The study indicated that low-dose gamma irradiation would increase the safety of blue swimming crab meat without unacceptable changes in texture and L* color value.

Two quantitative real-time PCR assays for the detection of penaeid shrimp and blue crab, crustacean shellfish allergens.

Science.gov (United States)

Eischeid, Anne C; Kim, Bang-hyun; Kasko, Sasha M

2013-06-19

Food allergen detection methods must be able to specifically detect minute quantities of an allergenic food in a complex food matrix. One technique that can be used is real-time PCR. For the work described here, real-time PCR assays were developed to detect penaeid shrimp and blue crab, crustacean shellfish allergens. The method was tested using shrimp meat and crab meat spiked into several types of foods, including canned soups, deli foods, meat, seafood, and prepared seafood products. Foods were spiked with either shrimp or crab at levels ranging from 0.1 to 10⁶ parts per million (ppm) and analyzed either raw or cooked by a variety of methods. Real-time PCR data were used to generate linear standard curves, and assays were evaluated with respect to linear range and reaction efficiency. Results indicate that both assays performed well in a variety of food types. High reaction efficiencies were achieved across a linear range of 6-8 orders of magnitude. Limits of detection were generally between 0.1 and 1 ppm. Cooking methods used to simulate thermal processing of foods had little effect on assay performance. This work demonstrates that real-time PCR can be a valuable tool in the detection of crustacean shellfish.

[Sex ratio and environmental influence on population growth rate of Callinectes bellicosus (Decapoda: Portunidae) in the Gulf of California].

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Rodríguez-Félix, Demetrio; Cisneros-Mata, Miguel Angel; Aragón-Noriega, Eugenio Alberto; Arreola-Lizárraga, José Alfredo

2016-09-01

The brown swimming crab (Callinectes bellicosus) is an economically important species in the Gulf of California, and its fishing activity, held in Sonora from 1986, has been affected by a 20-year declining trend in its biomass. With the aim to understand the possible reasons of this species population changes along time, we estimated population growth rate (r) and sex ratio of C. bellicosus, and combined them with three parameters describing its habitat: sea temperature, wetland extension and habitat size in four areas along the coast of Sonora. For this, monthly mean sex ratio was estimated from crabs samples obtained from commercial catches during 1998-2002 and 2012; mean sea surface temperature for the spawning period (May-August) were derived from remote sensors for the same years; while wetland coverages were obtained from published reports, and habitat size was estimated as the fishing surface. For each area, r was estimated using a method developed for limited data situations using commercial landings (t) from 1986-2013. With data from the four areas, simple and multiple linear regression models were developed to ascertain theoretical sensitivities of r to variations in sex ratio and environmental parameters. A total of 24 556 crabs were sampled; males dominated (68.8 %) over females during the study period and in all areas; a cluster analysis identified two groups according to sex ratio: a Northern group with zones 1 and 2, and a Southern group with zones 3 and 4. r values were different in all zones (P0.995). Both the estimated data and sensitivity analyses suggest the existence of a direct and positive dependence of r on the proportion of female crabs and wetland size. We hypothesize that excess fishing of females caused the declining biomass trend of the brown swimming crab in Sonora, and concluded on the convenience of implementing harvest refugia inside coastal wetlands to protect females during the spawning season.

AFSC/RACE/SAP/Long: Effects of ocean acidification on respiration, feeding, and growth of juvenile red and blue king crabs (Paralithodes camtschaticus and P. platypus)

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National Oceanic and Atmospheric Administration, Department of Commerce — Juvenile red and blue king crabs (Paralithodes camtschaticus and P. platypus) were exposed to three pH levels: ambient (pH 8.1), pH 7.8, and pH 7.5 for three weeks....

Biologia populacional de Callinectes ornatus (Ordway na Armação do Itapocoroy, Penha, Santa Catarina, Brasil Population biology of Callinectes ornatus (Ordway in the Armação do Itapocoroy, Santa Catarina, Brazil

Directory of Open Access Journals (Sweden)

Joaquim Olinto Branco

2004-03-01

Full Text Available Callinectes ornatus (Ordway, 1863 é a espécie mais abundante de Portunidae, capturada como fauna acompanhante na pesca artesanal do camarão sete-barbas. Durante o período de Agosto de 1996 a Julho de 2002, os caranguejos foram monitorados mensalmente na Armação do Itapocoroy. C. ornatus mostrou flutuações sazonais na abundância com as maiores taxas na primavera e no inverno. A variação da população quando a largura da carapaça variou de 2,0 a 10,0 cm, e a presença de juvenis foi comum ao longo do ano. As espécies apresentaram crescimento alométrico positivo, com os machos e as fêmeas chegando à primeira maturação gonadal com 5,8 e 5,2 cm, respectivamente. A pesca artesanal na Armação do Itapocoroy atua com alta intensidade sobre o estoque adulto.Callinectes ornatus (Ordway, 1863 is one abundant Portunidae species which is caught by sea-bob-shrimp's artisanal fishery in area. During the period from August, 1996 to July, 2002, the crabs were monitored monthly in the Armação do Itapocoroy. C. ornatus shows seasonal fluctuations in its abundance with higher rates in spring and winter. The population width variation of the carapace ranged from 2.0 to 10.0 cm, and the presence of juveniles was common along the year. The species present positive alometric growth, with males and females get to the first gonadal maturation with 5.8 cm and 5.2 cm, respectively. The artisanal fishery in Armação do Itapocory is acting with a higher intensity over the adult stock.

Inclusive blue swimming crab fishery management initiative in Betahwalang Demak, Indonesia

Science.gov (United States)

Ghofar, A.; Redjeki, S.; Madduppa, H.; Abbey, M.; Tasunar, N.

2018-02-01

There has been a growing interest in the sustainability of the blue swimming crab (Portunus pelagicus, BSC) fisheries in Indonesia. The fishery is operated on a small-scale basis and yet it significantly contributes to the Indonesia’s fisheries as the third biggest export commodities following tuna and shrimp. The project inclusively (i) brings together coastal and fishing communities, university, the private sector, government at various levels and international agencies, (ii) bottom up approach is integrated with top-down (government policy) approach and (iii) integration o f conservation into fisheries management. This approach resulted in better understanding and participation among the coastal fishing communities on sustainable fisheries and the necessity to perform fisheries management. This led to the establishment of BSC fishery management body (legally support by Village Regulation - No.06/2013 on BSC fishery management in 2013, followed by a District Regulation No.523/0166/2014 on BSC fishery management in 2014. More recently, the Governor of Central Java issued a Governor Regulation No. 33/2017 on Crab and Lobster fisheries management and a Governor Decree No. 523/93/2017 on the establishment of the BSC fisheries management committee in Central Java. Further impacts have been raised awareness in sustainable BSC fishery management in surrounding districts in other provinces, namely East Java and Southeast Sulawesi. There remains, further needs to strengthen fishery governance by means of integrating national and local government effort in sustaining the fisheries, including the Issuance and effective implementation of the provincial decree on BSC fishery management for Central Java, that will enable the use of province’s resource to implement fisheries management and strengthen law enforcement. To help improve the stock, a plan for stock enhancement should also be developed with proper monitoring program and community commitment to avoid “put and

Heavy metal bioaccumulation in Callinectes amnicola and ...

African Journals Online (AJOL)

The bioaccumulation of heavy metals in organisms is as a result of pollutants discharge generated by anthropogenic and natural activities which has become a tremendous concern in developing nations. The levels of cadmium, copper, chromium, lead, zinc and nickel in the tissue of Callinectes amnicola and ...

Bioinspired algorithm for autonomous sensor-driven guidance in turbulent chemical plumes

International Nuclear Information System (INIS)

Webster, D R; Volyanskyy, K Y; Weissburg, M J

2012-01-01

We designed and implemented a control algorithm for sensor-mediated chemical plume tracking in a turbulent flow environment. In our design, we focused on development of a signal processing strategy capable of replicating behavioral responses of actively tracking blue crabs (Callinectes sapidus) to chemical stimuli. The control algorithm is evaluated in a hardware platform that allows motion in two directions (i.e. forward–back and left–right). The geometric arrangement of the sensor array is inspired by the location of blue crab sensor populations. Upstream motion is induced by a binary response to supra-threshold spikes of concentration, and cross-stream steering is controlled by contrast between bilaterally-separated sensors. Like animal strategies, the developed control algorithm is dynamic. This property allows the algorithm to function effectively in the highly irregular turbulent environment and produces adaptive adjustments of motion to minimize the distance to the source of a plume. Tracking trials indicate that roughly 80% of the tracks successfully stop near the plume source location. Both success rate and movement patterns of the tracker compare favorably to that of blue crabs searching for odorant plume sources, thus suggesting that our sensory-mediated behavior hypothesis are generally accurate and that the associated tracking mechanisms may be successfully implemented in hardware. (paper)

Use of fully biodegradable panels to reduce derelict pot threats to marine fauna.

Science.gov (United States)

Bilkovic, D M; Havens, K J; Stanhope, D M; Angstadt, K T

2012-12-01

Fishing pots (i.e., traps) are designed to catch fish or crustaceans and are used globally. Lost pots are a concern for a variety of fisheries, and there are reports that 10-70% of deployed pots are lost annually. Derelict fishing pots can be a source of mortality for target and bycatch species for several years. Because continual removal of derelict gear can be impractical over large spatial extents, modifications are needed to disarm gear once it is lost. We tested a fully biodegradable panel with a cull or escape ring designed for placement on the sides of a crab pot that completely degrades into environmentally neutral constituents after approximately 1 year. This panel is relatively inexpensive, easy to install, and can be used in multiple fisheries. We used the blue crab (Callinectes sapidus) fishery as a test case because it is a large pot fishery and blue crab pots are similar to traps used in other pot fisheries. We had commercial fishers deploy pots with panels alongside standard pots in Chesapeake Bay (U.S.A.) to assess potential effects of our experimental pots on blue crab catch. We compared the number, biomass, and size of crabs captured between standard and experimental pots and evaluated differences in catch over a crabbing season (March-November) at five locations. There was no evidence that biodegradable panels adversely affected catch. In all locations and time periods, legal catches were comparable in abundance, biomass, and size between experimental and standard pots. Properly designed biodegradable panels appear to be a viable solution to mitigate adverse effects of derelict pots. ©2012 Society for Conservation Biology.

Mitochondrial DNA Variation Reveals a Sharp Genetic Break within the Distribution of the Blue Land Crab Cardisoma guanhumi in the Western Central Atlantic

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Maria Rosimere Xavier Amaral

2015-08-01

Full Text Available The blue land crab Cardisoma guanhumi is widely distributed throughout tropical and subtropical estuarine regions in the Western Central Atlantic (WCA. Patterns of population genetic structure and historical demographics of the species were assessed by mtDNA control region sequence analysis to examine the connectivity among five populations (n = 97 within the region for future conservation strategies and decision-making of fishery management. A total of 234 polymorphic nucleotides were revealed within the sequence region, which have defined 93 distinct haplotypes. No dominant mtDNA haplotypes were found but instead a distribution of a few low-frequency recurrent haplotypes with a large number of singletons. A NJ-tree and a median-joining haplotype network revealed two distinct clusters, corresponding to individuals from estuaries located along the Caribbean Sea and Brazilian waters, respectively. AMOVA and FST statistics supported the hypothesis that two main geographic regions exists. Phylogeographical discontinuity was further demonstrated by the Bayesian assignment analysis and a significant pattern of isolation-by-distance. Additionally, tests of neutral evolution and analysis of mismatch distribution indicate a complex demographic history in the WCA, which corresponds to bottleneck and subsequent population growth. Overall, a sharp genetic break between Caribbean and Brazilian populations raised concerns over the conservation status of the blue land crab.

Use of Hyperspectral Imagery to Assess Cryptic Color Matching in Sargassum Associated Crabs.

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Brandon J Russell

Full Text Available Mats of the pelagic macroalgae Sargassum represent a complex environment for the study of marine camouflage at the air-sea interface. Endemic organisms have convergently evolved similar colors and patterns, but quantitative assessments of camouflage strategies are lacking. Here, spectral camouflage of two crab species (Portunus sayi and Planes minutus was assessed using hyperspectral imagery (HSI. Crabs matched Sargassum reflectance across blue and green wavelengths (400-550 nm and diverged at longer wavelengths. Maximum discrepancy was observed in the far-red (i.e., 675 nm where Chlorophyll a absorption occurred in Sargassum and not the crabs. In a quantum catch color model, both crabs showed effective color matching against blue/green sensitive dichromat fish, but were still discernible to tetrachromat bird predators that have visual sensitivity to far red wavelengths. The two species showed opposing trends in background matching with relation to body size. Variation in model parameters revealed that discrimination of crab and background was impacted by distance from the predator, and the ratio of cone cell types for bird predators. This is one of the first studies to detail background color matching in this unique, challenging ecosystem at the air-sea interface.

Fecundity, embryonic and ovarian development of blue swimming crab, Portunus pelagicus (Linnaeus, 1758) in coastal water of Johor, Malaysia.

Science.gov (United States)

Ikhwanuddin, M; Azra, M N; Siti-Aimuni, H; Abol-Munafi, A B

2012-08-01

Blue swimming crab, Portunus pelagicus is widely study and research throughout the Indo-West Pacific, but little is known of its reproductive biology in Malaysia. The present study describes the fecundity, embryonic development and ovarian development stages of the P. pelagicus from Johor coastal water, Malaysia. Carapace width range of berried crabs sampled was from 9.64 to 13.32 cm, while the body weight range was from 75 to 235 g. The mean number of egg produced by females in different sizes ranged from 105443.333 +/- 35448.075 per eggs batch. Mean egg size during embryonic development at stage 1 was 0.307 +/- 0.037, while 0.386 +/- 0.039 and 0.396 +/- 0.033 for stage 2 and stage 3, respectively. Study showed that there was significant (p < 0.05) relationship between the number of eggs and carapace width/body weight. Mean diameter oocyte during ovarian development at stage 1 was 97.732 +/- 12.391 while for stage 2 was 149.516 +/- 23.287. Stage 3 showed increasingly of size with mean diameter was 158.506 +/- 27.616 and 181.013 +/- 24.339 for stage 4.

Etude microscopique de L'ovogenese chez la femelle de Callinectes ...

African Journals Online (AJOL)

Histological survey showed that the ovary of Callinectes amnicola was made of two elements, lobes of ovogonia and an amorphous zone. Both of them participate into ovogenesis. According to structural and ultrastructural aspects, process of the ovogenesis comprises five stages in which ovogonia change successively in ...

Diversity and distribution of Dorippid Crabs (Brachyura: Dorippidae) in East Coast of Lampung, Indonesia

Science.gov (United States)

Zairion; Hakim, AA; Mashar, A.; Fahrudin, A.; Adrianto, L.; Widigdo, B.; Wardiatno, Y.

2018-05-01

Dorippid crabs (Brachyura: Dorippidae) commonly live in sand or mud substrate at shallow coastal water. These crabs are a macro-benthos, mostly found in tropic, have no economic value, but have high abundance in blue swimming crab habitat and lack information in Indonesia. This study aims to determine diversity and species distribution of dorippid crabs in East Coast of Lampung, Indonesia. This study was conducted on March-April 2017 in seven locations along coastal area (i.e. Labuhan Maringgai, Kuala Penet, Sekopong, Wako, Seputih, Sungai Burung, and Kuala Teladas). The specimen was collected from the blue swimming crab gill-net fishery as by-catch. Each location found by this family was noted at coordinate point at satellite imagery map and processed using ArcGIS. Two species have been found, there are Dorippe quadridens and Dorippoides facchino. Both species were found at every location, except D. quadridens at Sungai Burung as well as D. facchino in Sekopong. There are 74% among the sample of fishermen caught D. quadridens in those areas with an average number of 36 individuals and weight of 959 grams. While, 40% of fishermen caught D. facchino with an average number of 17 individuals and weight 152 grams.

 The diversity of horseshoe crabs - protecting an endangered resource

DEFF Research Database (Denmark)

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

Horseshoe crabs are fascinating inhabitants of the sea represented by four living species, where three species live in Asia, while the fourth species lives on the East coast of North America. Ancient fossils, dating back to Ordovician 445 million years ago looks so similar to recent horseshoe crabs...... that people often call them "living fossils". Unfortunately, the existing populations are threatened by overfishing of the adults as well as by destruction and pollution of the beaches where they mate and deposit their eggs. All four extant species are on IUCN Red List of Threatened Species. The blue blood...... of the horseshoe crabs saves thousands of human lives every year. An extract from their blood are used worldwide to determine whether medicine, blood donations, and medical supplies are infected by bacteria or contain toxins. Horseshoe crabs are also fished for human consumption in Asia, are heavily used as bait...

Estructura de tallas y crecimiento de los cangrejos Callinectes arcuatus y C. bellicosus (Decapoda: Portunidae en la laguna costera Las Guásimas, México

Directory of Open Access Journals (Sweden)

Luis Hernández

2007-03-01

Full Text Available Presentamos información sobre la estructura de tallas, la relación ancho-peso y los parámetros de crecimiento de las jaibas Callinectes arcuatus y C. bellicosus. Las muestras fueron recolectadas mensualmente con una red de arrastre tipo camaronera durante el día y la noche desde marzo 1998 hasta febrero 2000 en una laguna costera del Golfo de California. C. bellicosus (n= 878 fue más abundante que C. arcuatus (n= 357 y su intervalo de talla de 8.4- 166 mm ancho del caparazón (AC y 9-130 mm AC, respectivamente. Ambas poblaciones son representadas principalmente por jóvenes (75 mm AC entre 37-75 mm AC y adultos entre 76- 90 mm AC. La relación ancho-peso mostró que los machos crecen más que las hembras en ambas especies y se observó una tendencia de crecimiento isométrico. Los parámetros de crecimiento para C. arcuatus estimados con el modelo von Bertalanffy fueron: K= 0.84 año-1, L∞= 140 a -0.12 mm para C. arcuatus, y K= 0.9 año -1, L∞= 169 a -0.11 mm para C. bellicosus. Estos resultados mostraron que la edad relativa a la cual se alcanza el crecimiento máximo es entre los tres y cuatro años de edad para ambas especies.Size frequency distribution and growth of the crabs Callinectes arcuatus and C. bellicosus (Decapoda: Portunidae in Las Guásimas coastal lagoon, Mexico. Information on size frequency distribution, the width-weight relation and growth parameters of the crabs Callinectes arcuatus and C. bellicosus is presented. The data comes from samples taken with a trawl net both day and night on a monthly basis from March 1998 to February 2000 in a coastal lagoon from Gulf of California. C. bellicosus (n= 878 was more abundant than C. arcuatus (n= 357 and its size frequency distribution presented carapace width CW ranges of 8.4-166 mm and 9-130 mm respectively. Both populations were mainly represented by juveniles (75 mm in CW ranging from 37 to 75 mm in CW, and adults (>75 mm in CW between 76 and 90 mm in CW. In both species

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.

Evolution of king crabs from hermit crab ancestors

Science.gov (United States)

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

1992-02-01

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

Natural Diet of Callinectes ornatus Ordway, 1863 (Decapoda, Portunidae in the Itapocoroy Inlet, Penha, SC, Brazil

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Joaquim Olinto Branco

2002-03-01

Full Text Available From January to December 1995, 332 individuals of the Callinectes ornatus species were collected from the Itapocoroy inlet in Penha, Sta. Catarina, Brazil to study its natural diet and the seasonal variations of diet. Results showed a diversified trophic spectrum with a generalized dietary strategy comprising the algae, macrophyta, foraminiferida, mollusca, polychaeta, crustacea, echinodermata, Osteichthyes and NIOM (Nonidentified Organic Matter groups.Alimentação natural de Callinectes ornatus Ordway, 1863 (Decapoda, Portunidae na Armação do Itapocoroy, Penha, SC - Brasil. No período de janeiro a dezembro de 1995, foram coletados 332 indivíduos de Callinectes ornatus, procedentes da Armação do Itapocoroy (Penha, SC. Foi estudada a alimentação natural da espécie e as variações sazonais da dieta. Os resultados mostram um espectro trófico diversificado, com estratégia alimentar generalista, sendo Algas, Macrófitas, Foraminiferida, Mollusca, Polychaeta, Crustacea, Echinodermata, Osteichthyes e matéria orgânica não identificada, os grupos que compõem sua dieta.

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

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

Science.gov (United States)

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

2006-10-01

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

Domestication de portunus validus et callinectes amnicola au Bénin ...

African Journals Online (AJOL)

Afin de diversifier les espèces candidates à l'aquaculture béninoise, des essais de domestication ont été réalisés sur deux espèces de crustacés lagunaires, Portunus validus et Callinectes amnicola. Des essais de croissance basés sur le nourrissage sur production primaire des étangs (mis en charge de 100 individus) et ...

The occurrence of Callinectes arcuatus ordway, 1863 (Crustacea, Decapoda, Portunidae in Bahia, Brazil

Directory of Open Access Journals (Sweden)

Edilson Pires de Gouvêa

1987-01-01

Full Text Available During the study of the Carcinofauna of the Bahian Coast, some Brachyura Portunidae were found. Some of these animals were Callinectes arcuatus Ordway, 1863 which has its distribution restricted to the Pacific Ocean, from California to Peru and the Galapagos Islands. This is the first occurrence of this species reported from the Atlantic Ocean and the Brazilian Coast (Bahia, 38º50'Wand 12º50'S.Durante o estudo da carcinofauna do litoral baiano, muitos Braquiuros Portunidae foram encontrados. Alguns destes animais foram Callinectes arcuatus Ordway, 1863 que possuia sua distribuição restrita da Califórnia ao Peru e Ilhas Galápagos, no Oceano Pacífico. Esta é a primeira ocorrência desta espécie no Oceano Atlântico e na Costa Brasileira. (Bahia, 12º50'S e 38º50'W.

Good Crab, Bad Crab

Science.gov (United States)

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

Crecimiento del cangrejo Callinectes danae (Decapoda: Portunidae de la Isla de Margarita, Venezuela

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Jesylén Castillo

2011-12-01

Full Text Available Las especies del género Callinectes sostienen pesquerías importantes en varias partes del mundo. En el occidente de Venezuela, Callinectes sapidus es capturado con palangre y sostiene una pesquería artesanal importante en el Lago de Maracaibo; mientras que en la Isla de Margarita, Callinectes danae es capturado con nasa en zonas cercanas a lagunas costeras y su pesca está limitada por la oferta y la demanda. Estos recursos son de considerable importancia económica entre los crustáceos comestibles; sin embargo, pocos estudios han sido reportados sobre la dinámica poblacional y potencialidad pesquera en ambientes costeros de Venezuela que contribuyan a la toma de decisiones en la administración pesquera. En este documento se presenta información de los parámetros de crecimiento del cangrejo Callinectes danae Smith, 1869, con el fin de obtener un conocimiento detallado del patrón de crecimiento y lograr estimaciones más precisas sobre el tamaño de la población y su disponibilidad para la explotación. Se analizó una muestra constituida por 3 623 ejemplares capturados con nasa cangrejera por la flota artesanal, entre octubre 2007 y septiembre 2008. Se estableció la relación longitud-peso y se estimaron los parámetros de crecimiento de las curvas en longitud y peso del modelo de von Bertalanffy. La proporción sexual global mostró que no existe diferencia significativa entre machos y hembras (χ2=0.04, p>0.05. Los valores de las pendientes b entre machos y hembras presentaron diferencias significativas (ts=2.75, p<0.05 igualmente los interceptos a (ts=2.44, p<0.05; por lo que se estableció la relación longitud-peso por separado: P=7.48e-5*L2.98 para machos y P=1.21e-4*L2.87 para hembras, evidenciándose un crecimiento alométrico negativo en ambos sexos. Los parámetros de crecimiento quedaron establecidos en: L∞=134.80mm, P∞=166.04g y k=0.86/año para machos; L∞=122.35mm, P∞=118.45g y k=0.63/año para hembras. La

Isolation and Tissue Distribution of an Insulin-Like Androgenic Gland Hormone (IAG of the Male Red Deep-Sea Crab, Chaceon quinquedens

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Amanda Lawrence

2017-08-01

Full Text Available The insulin-like androgenic gland hormone (IAG found in decapod crustaceans is known to regulate sexual development in males. IAG is produced in the male-specific endocrine tissue, the androgenic gland (AG; however, IAG expression has been also observed in other tissues of decapod crustacean species including Callinectes sapidus and Scylla paramamosain. This study aimed to isolate the full-length cDNA sequence of IAG from the AG of male red deep-sea crabs, Chaceon quinquedens (ChqIAG, and to examine its tissue distribution. To this end, we employed polymerase chain reaction cloning with degenerate primers and 5′ and 3′ rapid amplification of cDNA ends (RACE. The full-length ChqIAG cDNA sequence (1555 nt includes a 366 nt 5′ untranslated region a 453 nt open reading frame encoding 151 amino acids, and a relatively long 3′ UTR of 733 nt. The ORF consists of a 19 aa signal peptide, 32 aa B chain, 56 aa C chain, and 44 aa A chain. The putative ChqIAG amino acid sequence is most similar to those found in other crab species, including C. sapidus and S. paramamosain, which are clustered together phylogenetically.

Metabolomic analysis of marine and mud crabs based on antibacterial activity

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A.A. Laith

2017-08-01

Full Text Available Isolated compounds from marine invertebrates are being increasingly known to possess various pharmacological activities with which many useful drugs have been developed. Crabs contain bioactive compounds including antibacterial, antifungal and antiviral metabolites, isolated from various tissues and organs that have revolutionized treatment of serious diseases. The present study represents the first attempt to investigate and compare the natural antibacterial properties from whole extract of marine blue swimmer crab, Portunus pelagicus, and mud crab, Scylla tranquebarica, against fish pathogenic bacteria. Liquid chromatography/mass spectrometry utilizing a time-of-flight (TOF mass analyser (LC/MS-QTOF based metabolomics approach was used to characterize the variation in secondary metabolite production in P. pelagicus and S. tranquebarica crab habitats in Malaysia. Different metabolites are evaluated in both crab species using LC/MS-QTOF. Initially a total of 75 metabolites were identified and only 19 metabolites satisfied the P-Corr cut-off point of less than 0.01 and at least 2-fold change. These metabolites, which contain anti-inflammatory and antibacterial properties, were down regulated in S. tranquebarica samples and up regulated in P. pelagicus samples. In vitro bioassay of methanolic P. pelagicus extracts showed the best antimicrobial response against Gram positive bacteria, Streptococcus agalactiae, and Gram negative bacteria, Vibrio alginolyticus, Klebsiella pneumoniae, and Escherichia coli, with a statistically significant difference (P < 0.05 of P. pelagicus extracts as compared to S. tranquebarica. The results indicate that both types of crab extracts are bactericidal at higher concentrations and bacteriostatic at lower concentrations. This manuscript reports the role of marine and mud crabs with specific emphasis on their secondary metabolites, and discusses current and future developments in both the production of desired crab

Artificial lights improve the catchability of snow crab (Chionoecetes opilio traps

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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.

Tidal salt marshes of the southeast Atlantic Coast: A community profile

Energy Technology Data Exchange (ETDEWEB)

Wiegert, R.G.; Freeman, B.J.

1990-09-01

This report is part of a series of community profiles on the ecology of wetland and marine communities. This particular profile considers tidal marshes of the southeastern Atlantic coast, from North Carolina south to northern Florida. Alone among the earth's ecosystems, coastal communities are subjected to a bidirectional flooding sometimes occurring twice each day; this flooding affects successional development, species composition, stability, and productivity. In the tidally influenced salt marsh, salinity ranges from less than 1 ppt to that of seawater. Dominant plant species include cordgrasses (Spartina alterniflora and S. cynosuroides), black needlerush (Juncus romerianus), and salt marsh bulrush (Scirpus robustus). Both terrestrail and aquatic animals occur in salt marshes and include herons, egrets ospreys (Pandion haliaetus), bald eagles (Haliaeetus leucocephalus), alligators (Alligator Mississippiensis), manatees (Trichecus manatus), oysters, mussels, and fiddler crabs. Currently, the only significant direct commercial use of the tidal salt marshes is by crabbers seeking the blue crab Callinectes sapidus, but the marshes are quite important recreationally, aesthetically, and educationally. 151 refs., 45 figs., 6 tabs.

Distribución espacial y temporal del cangrejo Callinectes sapidus (Decapoda: Portunidae en la Bahía de Chetumal, Quintana Roo, México

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Héctor J Ortiz-León

2007-03-01

Full Text Available Para determinar los patrones de distribución espacial y temporal de Callinectes sapidus, se realizaron muestreos durante las temporadas climáticas de nortes (enerofebrero, secas (mayo-junio y lluvias (agosto-septiembre de 2002, en 30 estaciones de muestreo de la Bahía de Chetumal, agrupados en los sectores A (14 estaciones, B (ocho estaciones y C (ocho estaciones. Para recolectar las jaibas se colocaron en cada sitio de muestreo dos transectos paralelos a la costa, con tres trampas cada uno, separadas 30 m una de otra. Se recolecciónron 1 031 ejemplares de C. sapidus. La CPUE difirió espacial y temporalmente. La mayor CPUE fue encontrada en el sector C, con 1.3 ind∙trampa-1, y en la temporada climática de lluvias, con 1.1 ind∙trampa-1. La población estuvo compuesta predominantemente de individuos machos. La relación macho: hembra fue 15:1. La CPUE de machos y de adultos (grupo II fue significativamente diferente entre sectores y entre temporadas climáticas. Ambos presentaron resultados similares, registrando la mayor CPUE en el sector C (1.2 ind∙trampa-1 y en la temporada climática de lluvias (1.1 ind∙trampa-1. La CPUE de hembras y de jóvenes del grupo I fue escasa durante el período de muestreo, mientras que la de jóvenes del grupo 0, fue nula. La mayor frecuencia relativa entre los sectores y las temporadas climáticas se observó en los intervalos de talla (AC de 130-139 mm y 140-149 mm. C. sapidus se presentó en los sedimentos arenosos de la Bahía de Chetumal. La correlación producto momento de Pearson mostró relaciones significativas entre la CPUE de C. sapidus con la temperatura, salinidad y el oxígeno disuelto. Los patrones de distribución espacial y temporal mostrados por C. sapidus en la Bahía de Chetumal parecen estar relacionados con las características de salinidad, temperatura, protección, alimentación, reclutamiento y los eventos reproductivos.Temporal and spatial distribution of the crab Callinectes

Two opsins from the compound eye of the crab Hemigrapsus sanguineus

Science.gov (United States)

Sakamoto; Hisatomi; Tokunaga; Eguchi

1996-01-01

The primary structures of two opsins from the brachyuran crab Hemigrapsus sanguineus were deduced from the cDNA nucleotide sequences. Both deduced proteins were composed of 377 amino acid residues and included residues highly conserved in visual pigments of other species, and the proteins were 75 % identical to each other. The distribution of opsin transcripts in the compound eye, determined by in situ hybridization, suggested that the mRNAs of the two opsins were expressed simultaneously in all of the seven retinular cells (R1-R7) forming the main rhabdom in each ommatidium. Two different visual pigments may be present in one photoreceptor cell in this brachyuran crab. The spectral sensitivity of the compound eye was also determined by recording the electroretinogram. The compound eye was maximally sensitive at about 480 nm. These and previous findings suggest that both opsins of this brachyuran crab produce visual pigments with maximal absorption in the blue-green region of the spectrum. Evidence is presented that crustaceans possess multiple pigment systems for vision.

Capture and commercialization of blue land crabs ("guaiamum") Cardisoma guanhumi (Lattreille, 1825) along the coast of Bahia State, Brazil: an ethnoecological approach

Science.gov (United States)

2012-01-01

Background Blue Land Crab (Cardisoma guanhumi) is one of the most important crustacean species captured and commercialized in Brazil. Although this species is not considered to be threatened with extinction, populations of C. guanhumi are known to be rapidly diminishing due to heavy harvesting pressures and degradation of their natural habitats, highlighting the necessity of developing and implanting management and protection strategies for their populations. There have been no ethnozoological publications that have focused specifically on C. guanhumi, in spite of importance of this type of information for developing efficient management plans of resource utilization. So, the present work describes the ethnoecological aspects of the capture and commercialization of C. guanhumi by a fishing community in northeastern Brazil. Methods Field work was carried out in the municipality of Mucuri, Bahia in Brazil, between the months of January and March/2011 through the use of open semi-structured interviews with all of the crustacean harvesters in city who acknowledged their work in capturing this species, totaling 12 interviewees. The informants were identified through the use of the "snowball" sampling technique. In addition to the interviews themselves, the "guided tour" technique and direct observations was employed. Results According all the interviewees, the C. guanhumi is popularly called "guaiamum" and is collected in "apicum" zones. They recognize sexual dimorphism in the species based on three morphological characteristics and the harvesters also pointed two stages in the reproductive cycle during the year and another phase mentioned by the interviewees was ecdysis. All of the interviewed affirmed that the size and the quantities C. guanhumi stocks in Mucuri have been diminishing. All of the interviewees agreed that the species and other mangrove resources constituted their principal source of income. The harvesters dedicated three to five days a week to collect

Using Flow-Ecology Relationships to Evaluate Ecosystem Service Trade-Offs and Complementarities in the Nation's Largest River Swamp

Science.gov (United States)

Kozak, Justin P.; Bennett, Micah G.; Hayden-Lesmeister, Anne; Fritz, Kelley A.; Nickolotsky, Aaron

2015-06-01

Large river systems are inextricably linked with social systems; consequently, management decisions must be made within a given ecological, social, and political framework that often defies objective, technical resolution. Understanding flow-ecology relationships in rivers is necessary to assess potential impacts of management decisions, but translating complex flow-ecology relationships into stakeholder-relevant information remains a struggle. The concept of ecosystem services provides a bridge between flow-ecology relationships and stakeholder-relevant data. Flow-ecology relationships were used to explore complementary and trade-off relationships among 12 ecosystem services and related variables in the Atchafalaya River Basin, Louisiana. Results from Indicators of Hydrologic Alteration were reduced to four management-relevant hydrologic variables using principal components analysis. Multiple regression was used to determine flow-ecology relationships and Pearson correlation coefficients, along with regression results, were used to determine complementary and trade-off relationships among ecosystem services and related variables that were induced by flow. Seven ecosystem service variables had significant flow-ecology relationships for at least one hydrologic variable ( R 2 = 0.19-0.64). River transportation and blue crab ( Callinectes sapidus) landings exhibited a complementary relationship mediated by flow; whereas transportation and crawfish landings, crawfish landings and crappie ( Pomoxis spp.) abundance, and blue crab landings and blue catfish ( Ictalurus furcatus) abundance exhibited trade-off relationships. Other trade-off and complementary relationships among ecosystem services and related variables, however, were not related to flow. These results give insight into potential conflicts among stakeholders, can reduce the dimensions of management decisions, and provide initial hypotheses for experimental flow modifications.

Using Flow-Ecology Relationships to Evaluate Ecosystem Service Trade-Offs and Complementarities in the Nation's Largest River Swamp.

Science.gov (United States)

Kozak, Justin P; Bennett, Micah G; Hayden-Lesmeister, Anne; Fritz, Kelley A; Nickolotsky, Aaron

2015-06-01

Large river systems are inextricably linked with social systems; consequently, management decisions must be made within a given ecological, social, and political framework that often defies objective, technical resolution. Understanding flow-ecology relationships in rivers is necessary to assess potential impacts of management decisions, but translating complex flow-ecology relationships into stakeholder-relevant information remains a struggle. The concept of ecosystem services provides a bridge between flow-ecology relationships and stakeholder-relevant data. Flow-ecology relationships were used to explore complementary and trade-off relationships among 12 ecosystem services and related variables in the Atchafalaya River Basin, Louisiana. Results from Indicators of Hydrologic Alteration were reduced to four management-relevant hydrologic variables using principal components analysis. Multiple regression was used to determine flow-ecology relationships and Pearson correlation coefficients, along with regression results, were used to determine complementary and trade-off relationships among ecosystem services and related variables that were induced by flow. Seven ecosystem service variables had significant flow-ecology relationships for at least one hydrologic variable (R (2) = 0.19-0.64). River transportation and blue crab (Callinectes sapidus) landings exhibited a complementary relationship mediated by flow; whereas transportation and crawfish landings, crawfish landings and crappie (Pomoxis spp.) abundance, and blue crab landings and blue catfish (Ictalurus furcatus) abundance exhibited trade-off relationships. Other trade-off and complementary relationships among ecosystem services and related variables, however, were not related to flow. These results give insight into potential conflicts among stakeholders, can reduce the dimensions of management decisions, and provide initial hypotheses for experimental flow modifications.

Laboratory investigations of the effects of predator sex and size on prey selection by the Asian crab, Hemigrapsus sanguineus.

Science.gov (United States)

Brousseau, D J.; Filipowicz, A; Baglivo, J A.

2001-07-30

Laboratory studies have shown that the nonindigenous Asian shore crab, Hemigrapsus sanguineus, readily consumes three species of commercial bivalves: blue mussels, Mytilus edulis, soft-shell clams, Mya arenaria, and oysters, Crassostrea virginica. Although crabs can eat bivalves of a wide size range, they preferred the smaller prey (Hemigrapsus that occur in the wild, their effectiveness as predators of juvenile bivalves and their large appetites suggest an important role for these predators in restructuring the prey communities in habitats into which they have been introduced.

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.)

Survival and metamorphosis rate of swimming crab Portunus pelagicus larvae with the use of phytoecdysteroid in the artificial feed

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Andi Nikhlani

2017-07-01

Full Text Available ABSTRACT The survival rate of blue swimming crabs and the larval metamorphosis processes are still low in hatcheries. The objective of this study was to evaluate the effects of different phytoecdysteroids doses on both the survival and the rate of Blue swimmer crab larvae metamorphosis. The study consisted of four different phytoecdysteroids treatments, namely: control (0 mg/100 g of feed, 1 mg/100 g of feed, 2 mg/100 g of feed, and 4 mg/100 g of feed. Each treatment was replicated three times. The survival rate of the larvae was analyzed through analysis of variance, while the rate of larval metamorphosis was descriptively analyzed. The results showed that the dose of phytoecdysteroid of 2 mg/100 g of artificial feed resulted in the highest survival and the fastest metamorphosis speed of crab larvae for zoea-2 and zoea-3, and the dose of 4 mg/100 g of artificial feed for stadia megalopa and crablet. Keywords: phytoecdysteroids, survival rate, metamorphosis, blue swimming crab  ABSTRAK Kelangsungan hidup rajungan dalam pembenihan masih rendah, dan proses metamorfosis larva masih lambat. Tujuan penelitian ini adalah untuk mengevaluasi pengaruh pemberian fitoekdisteroid dosis berbeda terhadap kelangsungan hidup dan kecepatan metamorfosis larva rajungan. Penelitian ini terdiri atas empat perlakuan dosis fitoekdisteroid yang berbeda, yaitu: kontrol (0 mg/100 g pakan, 1 mg/100 g pakan, 2 mg/100 g pakan, dan 4 mg/100 g pakan dengan masing-masing perlakuan dilakukan tiga kali ulangan. Kelangsungan hidup larva dianalisis menggunakan analisis sidik ragam, sedangkan kecepatan metamorfosis larva dianalisis secara deskriptif. Hasil penelitian menunjukkan bahwa dosis fitoekdisteroid sebanyak 2 mg/100 g pakan buatan menghasilkan kelangsungan hidup tertinggi dan proses metamorfosis larva rajungan tercepat untuk stadia zoea-2 dan zoea-3, serta  dosis 4 mg/100 g pakan buatan untuk stadia megalopa dan crablet. Kata kunci: fitoekdisteroid, kelangsungan

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.

Maturidade sexual das fêmeas de Callinectes danae (Crustacea, Decapoda, Portunidae nos estuários dos rios Botafogo e Carrapicho, Itamaracá, PE, Brasil Sexual maturity of females of Callinectes danae (Crustacea, Decapoda, Portunidae in the estuaries of the Botafogo and Carrapicho rivers, Itamaracá, PE, Brazil

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Aline do Vale Barreto

2006-06-01

Full Text Available Callinectes danae (Smith, 1869, siri-azul, constitui um importante recurso pesqueiro nos estuários dos rios Botafogo e Carrapicho. O objetivo do presente estudo foi estimar a maturidade sexual das fêmeas de C. danae. Os espécimes foram capturados, entre outubro de 2003 a junho de 2004, com auxílio de um barco de pesca equipado com rede de arrasto do tipo "wing-trawl" e arrastados durante 5 minutos. No laboratório, os siris foram contados, numerados, sexados, pesados e mensurados. A largura da carapaça (LC foi medida na base do espinho lateral e a largura do abdome (LA mensurada na altura da articulação do quinto esternito abdominal. Um total de 596 fêmeas de C. danae foram analisadas: 417 (69,97% no rio Botafogo e 179 (30,03% no Carrapicho; as fêmeas não-ovígeras apresentaram LC de 18,38 a 101 mm (59,14 ± 13,65 mm e 26,70 a 83,48 mm (59,16 ± 13,77 mm, nos respectivos rios; a LC de fêmeas ovígeras foi de 57,04 a 83,30 mm (67,68 ± 6,56 mm. As médias de larguras das carapaças não apresentaram diferenças estatisticamente significativas O conhecimento da maturidade sexual das fêmeas de Callinectes danae é de grande importância para o seu manejo e conservação. O L50 gonadal foi estimado em 63,58 mm (chi2 = 140,47; g.l. = 1; p Callinectes danae (Smith, 1869 is an important fishery resource in the Botafogo and Carrapicho river estuaries. The aim of this study was to estimate the sexual maturity of C. danae. Specimens were captured between October 2003 and June 2004 with the aid of a fishing boat equipped with a wing-trawl and trawling took place during 5 minutes each time. In the laboratory, the crabs were counted, numbered, sexed, weighed, and measured. The carapace width (CW was measured at the base of the lateral spine and the abdomen width (AW was measured at the point of the articulation of the fifth abdominal esternite. A total of 596 females of C. danae were analyzed: 417 (69.97% from Botafogo River and 179 (30.03% from

Selection of shrimp breeders free of white spot syndrome and infectious hypodermal and hematopoietic necrosis

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Carlos Cesar de Mello Junior

2011-05-01

Full Text Available The objective of this work was to select surviving breeders of Litopenaeus vannamei from white spot syndrome virus (WSSV outbreak, adapted to local climatic conditions and negatively diagnosed for WSSV and infectious hypodermal and hematopoietic necrosis virus (IHHNV, and to evaluate if this strategy is a viable alternative for production in Santa Catarina, Brazil. A total of 800 males and 800 females were phenotypically selected in a farm pond. Nested-PCR analyses of 487 sexually mature females and 231 sexually mature males showed that 63% of the females and 55% of the males were infected with IHHNV. Animals free of IHHNV were tested for WSSV, and those considered double negative were used for breeding. The post-larvae produced were stocked in nine nursery tanks for analysis. From the 45 samples, with 50 post-larvae each, only two were positive for IHHNV and none for WSSV. Batches of larvae diagnosed free of virus by nested-PCR were sent to six farms. A comparative analysis was carried out in growth ponds, between local post-larvae and post-larvae from Northeast Brazil. Crabs (Chasmagnathus granulata, blue crabs (Callinectes sapidus, and sea hares (Aplysia brasiliana, which are possible vectors of these viruses, were also evaluated. The mean survival was 55% for local post-larvae against 23.4% for post-larvae from the Northeast. Sea hares showed prevalence of 50% and crabs of 67% of WSSV.

Crab cavities for linear colliders

CERN Document Server

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

2008-01-01

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

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...

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

Mangrove expansion into salt marshes alters associated faunal communities

Science.gov (United States)

Smee, Delbert L.; Sanchez, James A.; Diskin, Meredith; Trettin, Carl

2017-03-01

Climate change is altering the distribution of foundation species, with potential effects on organisms that inhabit these environments and changes to valuable ecosystem functions. In the Gulf of Mexico, black mangroves (Avicennia germinans) are expanding northward into salt marshes dominated by Spartina alterniflora (hereafter Spartina). Salt marshes are essential habitats for many organisms, including ecologically and economically important species such as blue crabs (Callinectes sapidus) and Penaeid shrimp (e.g., Penaeus aztecus), which may be affected by vegetation changes. Black mangroves occupied higher tidal elevations than Spartina, and Spartina was present only at its lowest tidal elevations in sites when mangroves were established. We compared nekton and infaunal communities within monoculture stands of Spartina that were bordered by mangroves to nearby areas where mangroves had not yet become established. Nekton and infaunal communities were significantly different in Spartina stands bordered by mangroves, even though salinity and temperature were not different. Overall abundance and biomass of nekton and infauna was significantly higher in marshes without mangroves, although crabs and fish were more abundant in mangrove areas. Black mangrove expansion as well as other ongoing vegetation shifts will continue in a warming climate. Understanding how these changes affect associated species is necessary for management, mitigation, and conservation.

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

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Murilo Zanetti Marochi

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

LHC crab-cavity aspects and strategy

International Nuclear Information System (INIS)

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

2010-01-01

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

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

Science.gov (United States)

2011-01-01

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

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

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

Science.gov (United States)

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

2011-11-16

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

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.

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...

Preservation of crab meat by gamma irradiation

International Nuclear Information System (INIS)

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

1972-01-01

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

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...

Antarctic crabs: invasion or endurance?

Directory of Open Access Journals (Sweden)

Huw J Griffiths

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

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...

Sterilizing effect of irradiation processing on drunk crab

International Nuclear Information System (INIS)

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

2001-01-01

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

Invertebrate predation on egg masses of the European cuttlefish, Sepia officinalis: An experimental approach

Science.gov (United States)

Martins, Catarina P. P.; Fernández-Álvarez, Fernando Á.; Villanueva, Roger

2018-01-01

The eggs of the European cuttlefish, Sepia officinalis, develop attached to the seafloor in shallow water habitats and possess a relatively thick black capsule that protects them from the surrounding environment. Since embryological development may take several months, eggs are vulnerable to a variety of threats present in shallow waters, including predation. This study investigates predation of S. officinalis eggs by benthic invertebrates. Twenty-eight invertebrate species from 6 different phyla and with diverse feeding habits were tested as potential predators under laboratory conditions. We also investigated how the feeding traits of these species are related to the mechanical ability to break the egg capsule and prey upon cuttlefish embryos. Species that fed on cuttlefish eggs were the sea snail Bolinus brandaris, the crab Cancer pagurus, the hermit crab Dardanus arrosor, the lobster Homarus gammarus, the invasive blue crab Callinectes sapidus, the shrimp Squilla mantis, the sea urchins Echinus melo, Cidaris sp. and Paracentrotus lividus and the starfish Astropecten aranciacus. It is of note that C. sapidus is a potential predatory crab, which raises the concern that this invasive species may constitute a novel threat for cuttlefish eggs as more populations become established in NE Atlantic waters. Of the biological traits examined, prey capture tools in the tested species best explained the experimental feeding results, suggesting that predation of S. officinalis eggs was determined generally by a mechanical factor and highlighting the importance of the protective egg capsule against predators. However, chemosensory factors are likely to be implicated as well. Thus, this work contributes to the understanding of the ecology of early life stages of cuttlefish and the factors that can affect offspring survival and subsequently impact the recruitment of this species.

Presence of gonadotropin-releasing hormone-like peptide in the central nervous system and reproductive organs of the male blue swimming crab, Portunus pelagicus, and its effect on spermatogenesis.

Science.gov (United States)

Senarai, Thanyaporn; Saetan, Jirawat; Tamtin, Montakan; Weerachatyanukul, Wattana; Sobhon, Prasert; Sretarugsa, Prepee

2016-08-01

Our previous studies have demonstrated that lamprey gonadotropin-releasing hormone-III (lGnRH-III)-like peptide occurs in the central nervous system (CNS) of decapod crustaceans (Macrobrachium rosenbergii, Penaeus monodon, Portunus pelagicus), and that lGnRH-III is the most potent in stimulating ovarian maturation compared with other GnRH isoforms. In this study, we examined the localization of lGnRH-III-like peptide in the CNS and male reproductive organs of the blue swimming crab by using anti-lGnRH-III as a probe. In the brain, lGnRH-III immunoreactivity (-ir) was detected in neurons of clusters 6, 10, 11, 14/15, 16, and 17 and in many neuropils. In the subesophageal ganglion, lGnRH-III-ir was present in neurons of the dorso-lateral and ventro-medial clusters. In the thoracic ganglia, lGnRH-III-ir was observed in the large-sized neurons between the thoracic neuropils and in the ventromedial cluster of the abdominal ganglia. In the testis, lGnRH-III-ir was detected in nurse cells, hemocytes, spermatids 2, and the outer and inner zones of the acrosomes of spermatozoa. Bioassay showed that lGnRH-III significantly increased the testis-somatic index, the percentage of late stages of seminiferous tubules (stages VII-IX), the diameter of the seminiferous tubules, and the number of BrdU-labeled early germ cells compared with the control groups. Thus, lGnRH-III-like peptide exists in the male crab and possibly enhances germ cell proliferation and maturation in the testes, leading to increased sperm production.

Spider Movement, UV Reflectance and Size, but Not Spider Crypsis, Affect the Response of Honeybees to Australian Crab Spiders

Science.gov (United States)

Llandres, Ana L.; Rodríguez-Gironés, Miguel A.

2011-01-01

According to the crypsis hypothesis, the ability of female crab spiders to change body colour and match the colour of flowers has been selected because flower visitors are less likely to detect spiders that match the colour of the flowers used as hunting platform. However, recent findings suggest that spider crypsis plays a minor role in predator detection and some studies even showed that pollinators can become attracted to flowers harbouring Australian crab spider when the UV contrast between spider and flower increases. Here we studied the response of Apis mellifera honeybees to the presence of white or yellow Thomisus spectabilis Australian crab spiders sitting on Bidens alba inflorescences and also the response of honeybees to crab spiders that we made easily detectable painting blue their forelimbs or abdomen. To account for the visual systems of crab spider's prey, we measured the reflectance properties of the spiders and inflorescences used for the experiments. We found that honeybees did not respond to the degree of matching between spiders and inflorescences (either chromatic or achromatic contrast): they responded similarly to white and yellow spiders, to control and painted spiders. However spider UV reflection, spider size and spider movement determined honeybee behaviour: the probability that honeybees landed on spider-harbouring inflorescences was greatest when the spiders were large and had high UV reflectance or when spiders were small and reflected little UV, and honeybees were more likely to reject inflorescences if spiders moved as the bee approached the inflorescence. Our study suggests that only the large, but not the small Australian crab spiders deceive their preys by reflecting UV light, and highlights the importance of other cues that elicited an anti-predator response in honeybees. PMID:21359183

Spider movement, UV reflectance and size, but not spider crypsis, affect the response of honeybees to Australian crab spiders.

Science.gov (United States)

Llandres, Ana L; Rodríguez-Gironés, Miguel A

2011-02-16

According to the crypsis hypothesis, the ability of female crab spiders to change body colour and match the colour of flowers has been selected because flower visitors are less likely to detect spiders that match the colour of the flowers used as hunting platform. However, recent findings suggest that spider crypsis plays a minor role in predator detection and some studies even showed that pollinators can become attracted to flowers harbouring Australian crab spider when the UV contrast between spider and flower increases. Here we studied the response of Apis mellifera honeybees to the presence of white or yellow Thomisus spectabilis Australian crab spiders sitting on Bidens alba inflorescences and also the response of honeybees to crab spiders that we made easily detectable painting blue their forelimbs or abdomen. To account for the visual systems of crab spider's prey, we measured the reflectance properties of the spiders and inflorescences used for the experiments. We found that honeybees did not respond to the degree of matching between spiders and inflorescences (either chromatic or achromatic contrast): they responded similarly to white and yellow spiders, to control and painted spiders. However spider UV reflection, spider size and spider movement determined honeybee behaviour: the probability that honeybees landed on spider-harbouring inflorescences was greatest when the spiders were large and had high UV reflectance or when spiders were small and reflected little UV, and honeybees were more likely to reject inflorescences if spiders moved as the bee approached the inflorescence. Our study suggests that only the large, but not the small Australian crab spiders deceive their preys by reflecting UV light, and highlights the importance of other cues that elicited an anti-predator response in honeybees.

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...

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.

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

Stable isotope and pen feeding trial studies confirm the value of horseshoe crab Limulus polyphemus eggs to spring migrant shorebirds in Delaware Bay

Science.gov (United States)

Haramis, G.M.; Link, W.A.; Osenton, P.C.; Carter, Daniel B.; Weber, R.G.; Clark, N.A.; Teece, M.A.; Mizrahi, D.S.

2007-01-01

We used stable isotope (SI) methods in combination with pen feeding trials to determine the importance of eggs of the Atlantic horseshoe crab Limulus polyphemus to migratory fattening of red knots Calidris canutus rufa and ruddy turnstones Arenaria interpres morinella during spring stopover in Delaware Bay. By manifesting measurable fractionation (ca +3?) and rapid turnover, blood plasma *15 nitrogen proved a functional marker for SI diet tracking during the short 3-week stopover. Blood samples from free-ranging knots (3 data sets) and turnstones (1 data set) produced similar convergence of plasma *15 N signatures with increasing body mass that indicated highly similar diets. Asymptotes deviated slightly (0.3? to 0.7?) from that of captive shorebirds fed a diet of only crab eggs during stopover, thus confirming a strong crab egg-shorebird linkage. The plasma *15N crab-egg diet asymptote was enriched ca +4.5? and therefore readily discriminated from that of either blue mussels Mytilus edulis or coquina clams Donax variabilis, the most likely alternative prey of knots in Delaware Bay. Crab eggs were highly palatable to captive knots and turnstones which achieved rates of mass gain (3?11 g/d) comparable to that of free-ranging birds. Peak consumption rates during hyperphagic events were 23,940 and 19,360 eggs/bird/d, respectively. The empirical conversions of eggs consumed to body mass gained (5,017 eggs/g for knots and 4,320 eggs/g for turnstones) indicate the large quantities of crab eggs required for the maintenance of these shorebird populations during stopover.

Pubic "Crab" Lice Prevention and Control

Science.gov (United States)

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

Atomic structure of intracellular amorphous calcium phosphate deposits.

Science.gov (United States)

Betts, F; Blumenthal, N C; Posner, A S; Becker, G L; Lehninger, A L

1975-06-01

The radial distribution function calculated from x-ray diffraction of mineralized cytoplasmic structures isolated from the hepatopancreas of the blue crab (Callinectes sapidus) is very similar to that previously found for synthetic amorphous calcium phosphate. Both types of mineral apparently have only short-range atomic order, represented as a neutral ion cluster of about 10 A in longest dimension, whose probable composition is expressed by the formula Ca9(PO4)6. The minor differences observed are attributed to the presence in the biological mineral of significant amounts of Mg-2+ and ATP. Synthetic amorphous calcium phosphate in contact with a solution containing an amount of ATP equivalent to that of the biological mineral failed to undergo conversion to the thermodynamically more stable hydroxyapatite. The amorphous calcium phosphate of the cytoplasmic mineral granules is similarly stable, and does not undergo conversion to hydroxyapatite, presumably owing to the presence of ATP and Mg-2+, known in inhibitors of the conversion process. The physiological implications of mineral deposits consisting of stabilized calcium phosphate ion clusters are discussed.

WAKEFIELD DAMPING FOR THE CLIC CRAB CAVITY

CERN Document Server

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

2009-01-01

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

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.

Comparative study of parasitic loads of Callinectes amnicola and ...

African Journals Online (AJOL)

The consumption of sea food especially crabs in the Niger Delta is an indelible aspect of the culinary culture of the people and a veritable avenue to contracting zoonotic infections. A comparative ... Also, protozoa had the highest prevalence in C. amnicola while nematodes had the highest prevalence in C. armatum.

Dicty_cDB: Contig-U06494-1 [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available .. 48 0.34 1 ( CV479322 ) CS_hyp_43e08_M13Reverse Blue crab hypodermis, nor... 48 0.34 1 ( CV303516 ) CS_hyp..._32b06_M13Reverse Blue crab hypodermis, nor... 48 0.34 1 ( CV303352 ) CS_hyp_32e1...1_M13Reverse Blue crab hypodermis, nor... 48 0.34 1 ( CV161987 ) CS_gil_49D09_M13Reverse Blue crab gill, nor

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.

Effects of ocean acidification on juvenile red king crab (Paralithodes camtschaticus and Tanner crab (Chionoecetes bairdi growth, condition, calcification, and survival.

Directory of Open Access Journals (Sweden)

William Christopher Long

Full Text Available Ocean acidification, a decrease in the pH in marine waters associated with rising atmospheric CO2 levels, is a serious threat to marine ecosystems. In this paper, we determine the effects of long-term exposure to near-future levels of ocean acidification on the growth, condition, calcification, and survival of juvenile red king crabs, Paralithodes camtschaticus, and Tanner crabs, Chionoecetes bairdi. Juveniles were reared in individual containers for nearly 200 days in flowing control (pH 8.0, pH 7.8, and pH 7.5 seawater at ambient temperatures (range 4.4-11.9 °C. In both species, survival decreased with pH, with 100% mortality of red king crabs occurring after 95 days in pH 7.5 water. Though the morphology of neither species was affected by acidification, both species grew slower in acidified water. At the end of the experiment, calcium concentration was measured in each crab and the dry mass and condition index of each crab were determined. Ocean acidification did not affect the calcium content of red king crab but did decrease the condition index, while it had the opposite effect on Tanner crabs, decreasing calcium content but leaving the condition index unchanged. This suggests that red king crab may be able to maintain calcification rates, but at a high energetic cost. The decrease in survival and growth of each species is likely to have a serious negative effect on their populations in the absence of evolutionary adaptation or acclimatization over the coming decades.

Are vent crab behavioral preferences adaptations for habitat choice?

Science.gov (United States)

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

2017-01-01

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

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

Science.gov (United States)

2010-10-01

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

Super-Acceleration in the Flaring Crab Nebula

Energy Technology Data Exchange (ETDEWEB)

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

2013-10-15

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

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.

Geographic Variation in Camouflage Specialization by a Decorator Crab.

Science.gov (United States)

Stachowicz, John J; Hay, Mark E

2000-07-01

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

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.

Effects of substrate type on growth and mortality of blue mussels ( Mytilus edulis ) exposed to the predator Carcinus maenas

DEFF Research Database (Denmark)

Frandsen, Rikke; Dolmer, Per

2002-01-01

Structure and complexity of the substrate are important habitat characteristics for benthic epifauna. The specific growth and mortality rates and inducible defence characters on medium- sized blue mussels (Mytilus edulis L.) exposed to shore crabs (Carcinus maenas L.) were examined on three...... different substrate types in combined field and laboratory experiments. The experiments showed that complexity of the substrate increased blue mussel survival significantly, through a decrease in predation pressure. However, increased intraspecific competition for food on the complex substrate resulted...... in significantly lower growth rates of the mussels. Inducible defence characters were also influenced by substrate type. Blue mussels were more affected by predators on the structurally simple substrate, where they developed thicker shells and a larger posterior adductor muscle....

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.

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 ...

Study on irradiation treatment to drunk crab

International Nuclear Information System (INIS)

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

2002-01-01

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

CLIC crab cavity design optimisation for maximum luminosity

Energy Technology Data Exchange (ETDEWEB)

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

2011-11-21

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

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.

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 ...

Identification of mud crab reovirus VP12 and its interaction with the voltage-dependent anion-selective channel protein of mud crab Scylla paramamosain.

Science.gov (United States)

Xu, Hai-Dong; Su, Hong-Jun; Zou, Wei-Bin; Liu, Shan-Shan; Yan, Wen-Rui; Wang, Qian-Qian; Yuan, Li-Li; Chan, Siuming Francis; Yu, Xiao-Qiang; He, Jian-Guo; Weng, Shao-Ping

2015-05-01

Mud crab reovirus (MCRV) is the causative agent of a severe disease in cultured mud crab (Scylla paramamosain), which has caused huge economic losses in China. MCRV is a double-stranded RNA virus with 12 genomic segments. In this paper, SDS-PAGE, mass spectrometry and Western blot analyses revealed that the VP12 protein encoded by S12 gene is a structural protein of MCRV. Immune electron microscopy assay indicated that MCRV VP12 is a component of MCRV outer shell capsid. Yeast two hybrid cDNA library of mud crab was constructed and mud crab voltage-dependent anion-selective channel (mcVDAC) was obtained by MCRV VP12 screening. The full length of mcVDAC was 1180 bp with an open reading frame (ORF) of 849 bp encoding a 282 amino acid protein. The mcVDAC had a constitutive expression pattern in different tissues of mud crab. The interaction between MCRV VP12 and mcVDAC was determined by co-immunoprecipitation assay. The results of this study have provided an insight on the mechanisms of MCRV infection and the interactions between the virus and mud crab. Copyright © 2015 Elsevier Ltd. All rights reserved.

Antimicrobial lipids from the hemolymph of brachyuran crabs

Digital Repository Service at National Institute of Oceanography (India)

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

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

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

CERN Document Server

Morita, A

2008-01-01

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

Status of LHC crab activity simulations and beam studies

International Nuclear Information System (INIS)

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

2009-01-01

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

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.

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.

PENGARUH PENCEMARAN LOGAM BERAT TERHADAP STRUKTUR POPULASI DAN ORGAN TUBUH RAJUNGAN (Portunus pelagicus, LINN

Directory of Open Access Journals (Sweden)

Arie Prabawa

2014-07-01

Full Text Available Blue Swimming crab (Portunus pelagicus is one of important fishery in Indonesia that captured nearshore on the bottom of the sea. There has been a significant water contamination on the Jakarta bay and the fishery are reported to be effected. Many heavy metals and other contaminants are introduced into the waters, sediments, and fishery that living in the bay. Heavy metals such as Pb, Cd, Hg and As are the most lethal contaminants and found in Jakarta Bay. This study aims to determine the effect of heavy metals contaminants to the blue swimming crab morphometric, body organs and population structure of blue swimming crabs in Jakarta bay, which compared to the study in healthier environment in Madura island. The results of this study showed that 1 The morphometric parameter of blue swimming crab population in Jakarta and Madura are significantly different. 2 The internal organ of the blue swimming crab (hepatopancreas, gonad and gill in Jakarta bay are also significantly different than in Madura. The histological analysis are confirmed some abnormal indication of the internal body of the blue swimming crab in Jakarta bay.3 Some population parameters of the blue swimming crab in jakarta bay are significantly different than in Madura island. The fishery structure in Jakarta bay showed the size of first maturity of the crabs is relatively smaller than in Madura and other area of Inodonesia. The fishery mangament based on spatial area management is recommended to apply in different area of Indonesia.

78 FR 21914 - North Pacific Fishery Management Council (NPFMC); Public Meeting

Science.gov (United States)

2013-04-12

...), Norton Sound Red King Crab (NSRKC), Pribilof Island Golden King Crab (PIGKC), Adak red king crab. Model update and reviews for Snow Crab, Tanner Crab, Saint Matthew Blue King Crab, Bristol Bay Red King Crab...

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.

The Dilemma of Derelict Gear.

Science.gov (United States)

Scheld, A M; Bilkovic, D M; Havens, K J

2016-01-21

Every year, millions of pots and traps are lost in crustacean fisheries around the world. Derelict fishing gear has been found to produce several harmful environmental and ecological effects, however socioeconomic consequences have been investigated less frequently. We analyze the economic effects of a substantial derelict pot removal program in the largest estuary of the United States, the Chesapeake Bay. By combining spatially resolved data on derelict pot removals with commercial blue crab (Callinectes sapidus) harvests and effort, we show that removing 34,408 derelict pots led to significant gains in gear efficiency and an additional 13,504 MT in harvest valued at US $21.3 million--a 27% increase above that which would have occurred without removals. Model results are extended to a global analysis where it is seen that US $831 million in landings could be recovered annually by removing less than 10% of the derelict pots and traps from major crustacean fisheries. An unfortunate common pool externality, the degradation of marine environments is detrimental not only to marine organisms and biota, but also to those individuals and communities whose livelihoods and culture depend on profitable and sustainable marine resource use.

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.

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.

Lattice Upgrade Plan for Crab Crossing at the KEKB Rings

CERN Document Server

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

2005-01-01

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

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.

Science support for evaluating natural recovery of polychlorinated biphenyl concentrations in fish from Crab Orchard Lake, Crab Orchard National Wildlife Refuge, Illinois

Science.gov (United States)

Kunz, Bethany K.; Hinck, Jo E.; Calfee, Robin D.; Linder, Greg L.; Little, Edward E.

2018-05-11

IntroductionCrab Orchard Lake in southern Illinois is one of the largest and most popular recreational lakes in the state. Construction of the nearly 7,000-acre reservoir in the late 1930s created employment opportunities through the Works Progress Administration, and the lake itself was intended to supply water, control flooding, and provide recreational opportunities for local communities (Stall, 1954). In 1942, the Department of War appropriated or purchased more than 20,000 acres of land around Crab Orchard Lake and constructed the Illinois Ordnance Plant, which manufactured bombs and anti-tank mines during World War II. After the war, an Act of Congress transferred the property to the U.S. Department of the Interior. Crab Orchard National Wildlife Refuge was established on August 5, 1947, for the joint purposes of wildlife conservation, agriculture, recreation, and industry. Production of explosives continued, but new industries also moved onsite. More than 200 tenants have held leases with Crab Orchard National Wildlife Refuge and have operated a variety of manufacturing plants (electrical components, plated metal parts, ink, machined parts, painted products, and boats) on-site. Soils, water, and sediments in several areas of the refuge were contaminated with hazardous substances from handling and disposal methods that are no longer acceptable environmental practice (for example, direct discharge to surface water, use of unlined landfills).Polychlorinated biphenyl (PCB) contamination at the refuge was identified in the 1970s, and a PCB-based fish-consumption advisory has been in effect since 1988 for Crab Orchard Lake. The present advisory covers common carp (Cyprinus carpio) and channel catfish (Ictalurus punctatus); see Illinois Department of Public Health (2017). Some of the most contaminated areas of the refuge were actively remediated, and natural ecosystem recovery processes are expected to further reduce residual PCB concentrations in the lake. The U

The smell of success: the amount of prey consumed by predators determines the strength and range of cascading non-consumptive effects

Directory of Open Access Journals (Sweden)

Marc Weissburg

2015-11-01

Full Text Available We examined whether chemically mediated risk perception by prey and the effects of changes in prey behavior on basal resources vary as a function of the amount of prey biomass consumed by the predator. We studied these issues using a tritrophic system composed of blue crabs, Callinectes sapidus (top predator, mud crabs Panopeus herbstii (intermediate prey, and oysters Crassostrea virginica (basal resource. Working in a well characterized field environment where experiments preserve natural patterns of water flow, we found that biomass consumed by a predator determines the range, intensity and nature of prey aversive responses. Predators that consume large amounts of prey flesh more strongly diminish consumption of basal resources by prey and exert effects over a larger range (in space and time compared to predators that have eaten less. Less well-fed predators produce weaker effects, with the consequence that behaviorally mediated cascades preferentially occur in refuge habitats. Well-fed predators affected prey behavior and increased basal resources up to distances of 1–1.5 m, whereas predators fed restricted diet evoked changes in prey only when they were extremely close, typically 50 cm or less. Thus, consumptive and non-consumptive effects may be coupled; predators that have a greater degree of predatory success will affect prey traits more strongly and non-consumptive and consumptive effects may fluctuate in tandem, with some lag. Moreover, differences among predators in their degree of prey capture will create spatial and temporal variance in risk cue availability in the absence of underlying environmental effects.

M10.3.4: CLIC crab cavity specifications completed

CERN Document Server

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

2010-01-01

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

CLIC CRAB CAVITY SPECIFICATIONS MILESTONE: M10.3.4

CERN Document Server

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

2010-01-01

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

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

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

Science.gov (United States)

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

2014-05-01

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

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

Science.gov (United States)

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

2015-12-30

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

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

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

Invasive Crabs in the Barents Sea

DEFF Research Database (Denmark)

Kaiser, Brooks; Fernandez, Linda; Kourantidou, Melina

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

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

Science.gov (United States)

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

2010-12-01

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

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

OpenAIRE

Wu, Q

2015-01-01

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

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.

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

Science.gov (United States)

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

2009-05-01

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

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

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

The Crab Nebula flaring activity

Energy Technology Data Exchange (ETDEWEB)

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

2014-12-12

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

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.;

Dicty_cDB: Contig-U13860-1 [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available yp_01d11_M13Reverse Blue crab hypodermis, nor... 42 2e-04 2 ( ET898754 ) CHO_OF145xg03f1.ab1 CHO_OF Nicotian...NG DRAF... 38 7e-04 2 ( CV303138 ) CS_hyp_27d12_M13Reverse Blue crab hypodermis, nor... 42 0.001 2 ( CV46305...2 ) CS_hyp_52b08_M13Reverse Blue crab hypodermis, nor... 40 0.001 2 ( CU468915 ) Zebrafish DNA sequence from

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

Science.gov (United States)

2010-10-01

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

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.

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).

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).

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

CERN Document Server

Wu, Q

2015-01-01

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

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 ...

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.

Summary of CARE-HHH Mini-Workshop on LHC Crab Cavity Validation, 21 August 2008

CERN Document Server

Calaga, R; Garoby, R; Linnecar, T; Tomás, R; Zimmermann, F; CERN. Geneva. BE Department

2008-01-01

A global LHC crab-cavity collaboration is rapidly advancing the R&D of a complete crab cavity cryomodule and performing the associated beam dynamics simulations compatible with a prototype test in the phase 0/I upgrade with the aim of establishing a full crab crossing scheme for the phase II upgrade of the LHC. A one day CARE-HHH mini-workshop was held on August 21, 2008 at CERN to discuss crab crossing in the LHC phase 0/I & II upgrades and this reports summarizes the activities of the four sessions that took place during the workshop. The goals of this crab-cavity workshop were fourfold: (1) to discuss prospects of crab cavities in LHC upgrades (2) to review the status of the cryomodule development and beam dynamics, (3) to establish validity requirements for LHC crab cavities which need to be demonstrated prior to their installation into the LHC, and (4) to provide guidance & coordination for the global collaborators.

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

Science.gov (United States)

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

2018-05-01

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

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.

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

Reproductive biology of the female Jonah crab from the Maryland-Virginia Coastal Zone

Science.gov (United States)

Dunn, H.; Stevens, B. G.

2016-02-01

Jonah crabs, Cancer borealis, have long been considered a bycatch of the lobster industry. Jonah crab harvest is not regulated, there are no fishing size limits, nor restrictions to protect females. The study sampled Jonah crabs from one area in the Maryland-Virginia coastal zone from a local fishing vessel in June and July of 2015. This study is based on examination of the gross anatomy of 49 crabs and on histological preparations from 29 crabs. Ovary development stages were created and ordered based on area of oocytes, color and size of ovary, and the presence of sperm plugs. Four stages were observed but five are identifiable. Size at 50% sexual maturity (SM50), for females, as indicated by vulvar condition and oocyte area, was estimated to be 49.46 mm carapace length (CL). No prior information or study has been published concerning female Jonah crabs. This fishery-independent data is vital to ensure long-term sustainability, and develop appropriate management for this species.

POLA BERAT DAGING RAJUNGAN BERDASARKAN BERAT TUBUH YANG TERTANGKAP DI PERAIRAN SELAT MADURA

Directory of Open Access Journals (Sweden)

Muhammad Zainuri

2016-11-01

Full Text Available Informations on ratio of meat blue swimming crab weight have both economically and ecological meanings.  The aim of this research is to know actual ratio of the weight of meat where as catches on Selat Madura fishing ground.  Samples were taken from October 2012 ~ December 2013 and May 2014 ~ November 2014 by longline and trammelnet.  The result showed that having tree (3 modes of average ratio of meat  blue swimming crab weight which reached highest on May, October and December of year; whereas the percentage of actual the weight of meat ( ratio between average of the weight of meat and body weight appeared on June and September of year. Consider result of Zainuri (2015 that the 10 cm wide carapace of blue swimming crab identical with  50 g of body weight, the result of this research also be known that there is tendency slightly increased of percentage of actual meat weight on blue swimming crab’s 50 g of body weight and more. Keywords: ratio of meat, Selat Madura, blue swimming crabPATTERN OF CRAB MEAT WEIGHT BASED ON BODY WEIGHT CAUGHT IN THE MADURA STRAITInformation on ratio of meat blue swimming crab weight have both economically and ecological meanings.  The aim of this research is to know actual ratio of the weight of meat whereas catches on Madura Strait fishing ground.  Samples were taken from October 2012 - December 2013 and May 2014 - November 2014 by long-line and trammel net.  The result showed that having tree (3 modes of average ratio of meat  blue swimming crab weight which reached highest on May, October and December of year; whereas the percentage of actual the weight of meat (ratio between average of the weight of meat and body weight appeared on June and September of year. The result of this research also be known that there is tendency slightly increased of percentage of actual meat weight on blue swimming crab’s 50 g of body weight and more.  Keywords: Ratio of meat, Body weight, Madura Strait, blue swimming

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.

The largest glitch observed in the Crab pulsar

Science.gov (United States)

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

2018-05-01

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

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

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...

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.

Preliminary study on domestication of coconut crab (Birgus latro

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. 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

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.

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...

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.

Dicty_cDB: Contig-U15654-1 [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available library Fra... 48 1.1 1 ( CV303527 ) CS_hyp_29e12_M13Reverse Blue crab hypodermis, nor... 48 1.1 1 ( CV30320...9 ) CS_hyp_26c04_M13Reverse Blue crab hypodermis, nor... 48 1.1 1 ( CV071224 ) CS_gil_39F04_M13Reverse Blue

Beam dynamics aspects of crab cavities in the CERN Large Hadron Collider

CERN Document Server

Sun, Y P; Barranco, J; Tomás, R; Weiler, T; Zimmermann, F; Calaga, R; Morita, A

2009-01-01

Modern colliders bring into collision a large number of bunches to achieve a high luminosity. The long-range beam-beam effects arising from parasitic encounters at such colliders are mitigated by introducing a crossing angle. Under these conditions, crab cavities (CC) can be used to restore effective head-on collisions and thereby to increase the geometric luminosity. Such crab cavities have been proposed for both linear and circular colliders. The crab cavities are rf cavities operated in a transverse dipole mode, which imparts on the beam particles a transverse kick that varies with the longitudinal position along the bunch. The use of crab cavities in the Large Hadron Collider (LHC) may not only raise the luminosity, but it could also complicate the beam dynamics, e.g., crab cavities might not only cancel synchrobetatron resonances excited by the crossing angle but they could also excite new ones, they could reduce the dynamic aperture for off-momentum particles, they could influence the aperture and orbit...

Cholesterol Effect on Survival and Development of Larval Mud Crab Scylla serrata

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MUHAMMAD AGUS SUPRAYUDI

2012-03-01

Full Text Available The effect of cholesterol on the survival and development of larval mud crab Scylla serrata were examined by feeding larvae with Artemia enriched with different level of cholesterol. Artemia enriched with four stated levels of cholesterol i.e., 0, 5, 10, and 20 ul/l (Chol 0, 5, 10, and 20. All treatments were mixed with DHA70G at 25 ul/l. All the oil was adjusted to 100 ul/l by adding the oleic acid. Survival rate, intermolt period, and carapace width at the fisrt crab stage of mud crab larvae fed Chol 0, 5, and 10 were higher compared to that of Chol 20 (P < 0.05. We suggest that free sterol contained in Artemia at 1.37% was harmful to the growth performance of mud crab larvae. This study suggests that mud crab larvae required at least 0.61% cholesterol for maintaining good survival and development and therefore no need to enrich Artemia by cholesterol for the practical purpose.

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

Science.gov (United States)

McGaw, I J

2003-02-01

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

Space Movie Reveals Shocking Secrets Of The Crab Pulsa

Science.gov (United States)

2002-09-01

Just when it seemed like the summer movie season had ended, two of NASA's Great Observatories have produced their own action movie. Multiple observations made over several months with NASA's Chandra X-ray Observatory and the Hubble Space Telescope captured the spectacle of matter and antimatter propelled to near the speed of light by the Crab pulsar, a rapidly rotating neutron star the size of Manhattan. "Through this movie, the Crab Nebula has come to life," said Jeff Hester of Arizona State University in Tempe, lead author of a paper in the September 20th issue of The Astrophysical Journal Letters. "We can see how this awesome cosmic generator actually works." The Crab was first observed by Chinese astronomers in 1054 A.D. and has since become one of the most studied objects in the sky. By combining the power of both Chandra and Hubble, the movie reveals features never seen in still images. By understanding the Crab, astronomers hope to unlock the secrets of how similar objects across the universe are powered. Crab Nebula Composite Image Crab Nebula Composite Image Bright wisps can be seen moving outward at half the speed of light to form an expanding ring that is visible in both X-ray and optical images. These wisps appear to originate from a shock wave that shows up as an inner X-ray ring. This ring consists of about two dozen knots that form, brighten and fade, jitter around, and occasionally undergo outbursts that give rise to expanding clouds of particles, but remain in roughly the same location. "These data leave little doubt that the inner X-ray ring is the location of the shock wave that turns the high-speed wind from the pulsar into extremely energetic particles," said Koji Mori of Penn State University in University Park, a coauthor of the paper. Another dramatic feature of the movie is a turbulent jet that lies perpendicular to the inner and outer rings. Violent internal motions are obvious, as is a slow motion outward into the surrounding nebula of

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

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Wei Li

2015-07-01

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

New Mediterranean Biodiversity Records (October, 2014

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S. KATSANEVAKIS

2014-11-01

Full Text Available The Collective Article ‘New Mediterranean Biodiversity Records’ of the Mediterranean Marine Science journal offers the means to publish biodiversity records in the Mediterranean Sea. The current article is divided in two parts, for records of alien and native species respectively. The new records of alien species include: the red alga Asparagopsis taxiformis (Crete and Lakonicos Gulf (Greece; the red alga Grateloupia turuturu (along the Israeli Mediterranean shore; the mantis shrimp Clorida albolitura (Gulf of Antalya, Turkey; the mud crab Dyspanopeus sayi (Mar Piccolo of Taranto, Ionian Sea; the blue crab Callinectes sapidus (Chios Island, Greece; the isopod Paracerceis sculpta (northern Aegean Sea, Greece; the sea urchin Diadema setosum (Gökova Bay, Turkey; the molluscs Smaragdia souverbiana, Murex forskoehlii, Fusinus verrucosus, Circenita callipyga, and Aplysia dactylomela (Syria; the cephalaspidean mollusc Haminoea cyanomarginata (Baia di Puolo, Massa Lubrense, Campania, southern Italy; the topmouth gudgeon Pseudorasbora parva (Civitavecchia, Tyrrhenian Sea; the fangtooth moray Enchelycore anatine (Plemmirio marine reserve, Sicily; the silver-cheeked toadfish Lagocephalus sceleratus (Saros Bay, Turkey; and Ibiza channel, Spain; the Indo-Pacific ascidian Herdmania momusin Kastelorizo Island (Greece; and the foraminiferal Clavulina multicam erata (Saronikos Gulf, Greece. The record of L. sceleratus in Spain consists the deepest (350-400m depth record of the species in the Mediterranean Sea. The new records of native species include: first record of the ctenophore Cestum veneris in Turkish marine waters; the presence of Holothuria tubulosa and Holothuria polii in the Bay of Igoumenitsa (Greece; the first recorded sighting of the bull ray Pteromylaeus bovinus in Maltese waters; and a new record of the fish Lobotes surinamensis from Maliakos Gulf.

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.

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

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...

Spiny lobsters detect conspecific blood-borne alarm cues exclusively through olfactory sensilla.

Science.gov (United States)

Shabani, Shkelzen; Kamio, Michiya; Derby, Charles D

2008-08-01

When attacked by predators, diverse animals actively or passively release molecules that evoke alarm and related anti-predatory behavior by nearby conspecifics. The actively released molecules are alarm pheromones, whereas the passively released molecules are alarm cues. For example, many insects have alarm-signaling systems that involve active release of alarm pheromones from specialized glands and detection of these signals using specific sensors. Many crustaceans passively release alarm cues, but the nature of the cues, sensors and responses is poorly characterized. Here we show in laboratory and field experiments that injured Caribbean spiny lobsters, Panulirus argus, passively release alarm cues via blood (hemolymph) that induce alarm responses in the form of avoidance and suppression of feeding. These cues are detected exclusively through specific olfactory chemosensors, the aesthetasc sensilla. The alarm cues for Caribbean spiny lobsters are not unique to the species but do show some phylogenetic specificity: P. argus responds primarily with alarm behavior to conspecific blood, but with mixed alarm and appetitive behaviors to blood from the congener Panulirus interruptus, or with appetitive behaviors to blood from the blue crab Callinectes sapidus. This study lays the foundation for future neuroethological studies of alarm cue systems in this and other decapod crustaceans.

New Mediterranean Marine biodiversity records (December, 2013

Directory of Open Access Journals (Sweden)

M. BILECENOGLU

2013-10-01

Full Text Available Based on recent biodiversity studies carried out in different parts of the Mediterranean, the following 19 species are included as new records on the floral or faunal lists of the relevant ecosystems: the green algae Penicillus capitatus (Maltese waters; the nemertean Amphiporus allucens (Iberian Peninsula, Spain; the salp Salpa maxima (Syria; the opistobranchs Felimida britoi and Berghia coerulescens (Aegean Sea, Greece; the dusky shark Carcharhinus obscurus (central-west Mediterranean and Ionian Sea, Italy; Randall’s threadfin bream Nemipterus randalli, the broadbanded cardinalfish Apogon fasciatus and the goby Gobius kolombatovici (Aegean Sea, Turkey; the reticulated leatherjack Stephanolepis diaspros and the halacarid Agaue chevreuxi (Sea of Marmara, Turkey; the slimy liagora Ganonema farinosum, the yellowstripe barracuda Sphyraena chrysotaenia, the rayed pearl oyster Pinctada imbricata radiata and the Persian conch Conomurex persicus (south-eastern Crete, Greece; the blenny Microlipophrys dalmatinus and the bastard grunt Pomadasys incisus (Ionian Sea, Italy; the brown shrimp Farfantepenaeus aztecus (north-eastern Levant, Turkey; the blue-crab Callinectes sapidus (Corfu, Ionian Sea, Greece. In addition, the findings of the following rare species improve currently available biogeographical knowledge: the oceanic pufferfish Lagocephalus lagocephalus (Malta; the yellow sea chub Kyphosus incisor (Almuñécar coast of Spain; the basking shark Cetorhinus maximus and the shortfin mako Isurus oxyrinchus (north-eastern Levant, Turkey.

Evaluation of a Florida coastal golf complex as a local and watershed source of bioavailable contaminants

International Nuclear Information System (INIS)

Lewis, Michael A.; Quarles, Robert L.; Dantin, Darrin D.; Moore, James C.

2004-01-01

Contaminant fate in coastal areas impacted by golf course runoff is not well understood. This report summarizes trace metal, pesticide and PCB residues for colonized periphyton, Ruppia maritima (widgeon grass), Callinectes sapidus Rathbun (blue crabs) and Crassostrea virginica Gemlin (Eastern oyster) collected from areas adjacent to a Florida golf course complex which receive runoff containing reclaimed municipal wastewater. Concentrations of 19 chlorinated pesticides and 18 PCB congeners were usually below detection in the biota. In contrast, 8 trace metals were commonly detected although concentrations were not usually significantly different for biota collected from reference and non-reference coastal areas. Residue concentrations in decreasing order were typically: zinc, arsenic, copper, chromium, lead, nickel, cadmium and mercury. Mean BCF values for the eight trace metals ranged between 160-57 000 (periphyton), 79-11 033 (R. maritima), 87-162 625 (C. virginica) and 12-9800 (C. sapidus). Most trace metal residues in periphyton colonized adjacent to the golf complex, were either similar to or significantly less than those reported for periphyton colonized in nearby coastal areas impacted by urban stormwater runoff and treated municipal and industrial wastewater discharges. Consequently, the recreational complex does not appear to be a major source of bioavailable contaminants locally nor in the immediate watershed based on results for the selected biota

75 FR 52511 - North Pacific Fishery Management Council; Notice of Public Meeting

Science.gov (United States)

2010-08-26

...; review Bristol Bay red king crab CIE report, review and recommend approaches for Tanner crab model, review and recommend approaches for Pribilof Islands blue king crab and red king crab models, receive an...: results of the 2010 survey; snow crab spatial model and management strategy evaluation projects; discuss...

Snow crab allergy and asthma among Greenlandic workers – a pilot study

Directory of Open Access Journals (Sweden)

Jakob Hjort Bønløkke

2012-08-01

Full Text Available Objectives. To study snow crab sensitization, occupational allergy and asthma in the snow crab industry in Greenland, as high rates have been found in Canada, but no reports have emerged from the same industry in Greenland. Study design. Pilot survey. Methods. Twenty workers (19 of Inuit and 1 of other origin in a snow crab (Chionoecetes opilio and Atlantic shrimp (Pandalus borealis processing plant in Greenland were assessed with skin prick tests (SPTs with common aeroallergens and specific allergens from snow crab and shrimp extracts, spirometry, blood sampling for total IgE and specific IgE determination. Eighteen workers contributed a questionnaire-based medical interview. Results. Positive skin prick test reactions were common to snow crab (40% and shrimp (20%. Specific IgE to snow crab were positive in 4 workers (21%. Two workers had elevated total IgE levels. Symptoms suggestive of asthma were common (45%. Work-related symptoms of skin rash, rhinitis, and/or conjunctivitis were reported by 50%, and symptoms from the lower airways by 39%. Combining history of work-related symptoms with results from specific SPTs and/or specific IgE determination suggested that 11 and 22% of workers suffered from probable and possible occupational asthma, respectively, whereas 22% had possible occupational dermatitis or rhinitis. Conclusions. Greenlander Inuit do not appear to be protected against sensitization to snow crab or shrimp when occupationally exposed to these. This pilot study suggests that occupational allergy and asthma may be as common a problem in Greenlandic workers as in Canadian.

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...

Arsenobetaine in the red crab, Chionoecetes opilio

Energy Technology Data Exchange (ETDEWEB)

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

1986-01-01

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

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...

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.

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...

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...

Idade e crescimento de Callinectes danae e C. ornatus (Crustacea, Decapoda na Baía de Guanabara, Rio de Janeiro, Brasil Age and growth of Callinectes danae and C. ornatus (Crustacea, Decapoda in Guanabara Bay, Rio de Janeiro, Brazil

Directory of Open Access Journals (Sweden)

Karina A. Keunecke

2008-06-01

Full Text Available Callinectes danae Smith, 1869 e C. ornatus Ordway, 1863 constituem uma parcela importante da produção pesqueira na Baía de Guanabara. Ambas espécies compõem uma fração significativa da fauna-acompanhante sendo exaustivamente descartadas pelas pescarias de arrasto de camarões na costa brasileira. As curvas de crescimento de C. danae e C. ornatus foram calculadas por meio da análise de progressão modal. Para estimar os parâmetros biológicos, foi aplicado o modelo de crescimento de Bertalanffy e para estimar a longevidade foi usada a sua fórmula inversa. As curvas de crescimento foram: ♂ LC = 120 (1 - e -0,005t , ♀ LC = 113 (1 - e -0,005t; ♂ LC = 94 (1 - e -0,005t e ♀ LC = 110 (1 - e -0,005t , respectivamente para C. danae e C. ornatus. A longevidade alcançada para as duas espécies foi em torno de 2,5 anos, além de validar as curvas de crescimento. O estudo do crescimento em crustáceos é de extrema importância, pois além de fornecer a informação biológica básica para o grupo, os parâmetros estimados subsidiam o ordenamento e manejo pesqueiro das espécies exploradas.Callinectes danae Smith, 1869 and C. ornatus Ordway, 1863 constitute an important portion from the fishing products at Guanabara Bay. Both species compose a significant by-catch fraction being a lot discarded during shrimp trawlings along Brazilian coast. Growth curves were estimated by modal progression analysis. For the biological parameters it was applied the Bertalanffy growth function and for the age it was used its inverse formula. Growth curves of C. danae and C. ornatus were respectively: ♂ LC = 120 (1 - e -0,005t, ♀ LC = 113 (1 - e -0,005t; ♂ LC = 94 (1 - e -0,005t and ♀ LC = 110 (1 - e -0,005t. The age for both species reached around 2.5 years, besides to confirm growth curves. Growth study in crustaceans is very important, because besides supplying biological information it subsidizes fishery management for exploted species.

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.

Polarization and emission geometry of the Crab pulsar

International Nuclear Information System (INIS)

Kaiyou Chen; Cheng Ho

1993-01-01

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

Beam losses due to abrupt crab cavity failures in the LHC

International Nuclear Information System (INIS)

Baer, T.; Barranco, J.; Calaga, R.; Tomas, R.; Wenninger, B.; Yee, B.; Zimmermann, F.

2011-01-01

A major concern for the implementation of crab crossing in a future High-Luminosity LHC (HL-LHC) is machine protection in an event of a fast crab-cavity failure. Certain types of abrupt crab-cavity amplitude and phase changes are simulated to characterize the effect of failures on the beam and the resulting particle-loss signatures. The time-dependent beam loss distributions around the ring and particle trajectories obtained from the simulations allow for a first assessment of the resulting beam impact on LHC collimators and on sensitive components around the ring. Results for the nominal LHC lattice is presented.

Isolation and characterisation of chitin and chitosan from local sources

International Nuclear Information System (INIS)

Iqbal, M.K.; Khan, R.A.

2014-01-01

In this study, indigenous shrimp (Gadus morhua) and blue crab (Portunus pelagius, male and female) from Karachi coastal area were collected. The flesh was extracted to use for eating and the discarded waste was converted to an environment-friendly value-added product chitosan in chemical process after minor modification of DMCPA protocol. Four chitosan samples of shrimp head shells, blue crab leg shells, claw shells and carapace were obtained. The physicochemical and functional properties i.e., colour, degree of deacetylation, moisture, ash contents, nitrogen, viscosity, water and fat binding capacities were evaluated. Comparative study showed good percentage yields of chitosan from crab leg and shrimp head shells as 25.67% and 22.06%, respectively. Moisture, ash and nitrogen contents were in acceptable ranges. The colour of blue crab leg shell was off-white, while other three were light-yellow. Difference in degree of deacetylation (DD) was significant. The DD was 77% in crab leg shell, 61.6% shrimp head shells, 25.5% crab claw shell and 20.4% for crab carapace chitosan samples. Viscosity values were low (41-116 cPs). Water and fat binding capacity were in range of 494-521 % and 378-428 %, respectively. (author)

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

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

Science.gov (United States)

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

2018-03-01

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

Present and future distributions of horseshoe crabs under predicted climate changes

DEFF Research Database (Denmark)

Funch, Peter; Obst, Matthias; Quevedo, Francisco

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

Responses of the crab Heterozius rotundifrons to heterospecific chemical alarm cues: phylogeny vs. ecological overlap.

Science.gov (United States)

Hazlett, Brian A; McLay, Colin

2005-03-01

The big-handed brachyuran crab Heterozius rotundifrons extends the time spent in its anti-predator posture, limb extended posture, if exposed to chemical cues from crushed conspecifics. In this study, we tested whether crabs also respond to chemical cues from crushed heterospecific crabs, and if so, whether phylogenetic relations or ecological overlap is more important in influencing the duration of the anti-predator posture. Chemical cues from two other brachyuran crabs (Cyclograpsus lavauxi and Hemigrapsus sexdentatus), which do not overlap directly in ecological distribution with H. rotundifrons, elicited a duration of the anti-predator posture that was indistinguishable from that produced by conspecific chemical cues. In contrast, chemical cues from two anomuran crabs (Petrolisthes elongatus and Pagurus novizealandiae) that overlap in ecological distribution with H. rotundifrons, elicited durations of the antipredator posture that were significantly shorter than those of either conspecifics or more closely related crab species. Thus, phylogenetic relationship seems to be more important than ecological overlap in influencing anti-predator behavior in H. rotundifrons.

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

Science.gov (United States)

Teoh, Hong Wooi; Chong, Ving Ching

2014-02-01

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

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.

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.

Interference competition as a key determinant for spatial distribution of mangrove crabs

KAUST Repository

Cannicci, Stefano; Fusi, Marco; Cimó , Filippo; Dahdouh-Guebas, Farid; Fratini, Sara

2018-01-01

The spatial distribution of mangrove crabs has been commonly associated with tree zonation and abiotic factors such as ground temperature and soil granulometry. Conversely, no studies were designed to investigate the role of competition for resources and predation in shaping crab distribution in mangroves, despite these biotic factors are recognised as key determinants for spatial patterns observed in the communities colonising rocky and sandy intertidal habitats.We studied floral and faunal assemblages in two zones of a Sri Lankan mangrove, a man-made upper intertidal level and a natural eulittoral, mid-shore one. Leaf choice experiments were designed to study both feeding rate and intra and inter-specific interactions for food of sesarmid crabs in the two habitats in order to better understand crab spatial distribution.The two intertidal belts differed in terms of floral composition and crab species abundance. The eulittoral zone was strongly dominated by Neosarmatium smithi, while within the elevated littoral fringe four sesarmids (N. smithi, N. asiaticum, N. malabaricum and Muradium tetragonum) were more evenly distributed. At both levels, all sesarmids showed to collect significantly more Bruguiera spp. and Rhizophora apiculata leaves than Excoecaria agallocha ones. There was no temporal segregation in feeding activity among the four species, resulting in a high interference competition for leaves. Regardless of the habitat, N. smithi was always successful in winning inter-specific fights.Our results showed that the elevated littoral fringe was more crowded with crabs, but was less favourable in terms of food availability and environmental conditions. The dominance of N. smithi in gathering mangrove leaves suggests that this species may segregate the other sesarmids into less favourable habitats. The present data strongly suggest for the first time that interference competition for food can contribute to shape mangrove crab spatial distribution.

Hypolobocera guayaquilensis (Decapoda: Pseudothelphusidae): A New Crab Intermediate Host of Paragonimus mexicanus in Manabí Province, Ecuador

Science.gov (United States)

Calvopina, Manuel; Romero-Alvarez, Daniel; Rendon, Melina; Takagi, Hidekazu; Sugiyama, Hiromu

2018-01-01

To determine that Paragonimus sp. is actively transmitted in a tropical area of the Pacific region of Ecuador where human cases of pulmonary paragonimiasis have recently been documented, a total of 75 freshwater crabs were collected from 2 different streams in the Pedernales area of Manabí Province, Ecuador. All collected crabs were identified as Hypolobocera guayaquilensis based on morphological characteristics of the male gonopods. The hepatopancreas of each crab was examined by compressing it between 2 glass plates followed by observation under a stereomicroscope. Excysted Paragonimus metacercariae were detected in 39 (52.0%) crabs and their densities varied from 1 to 32 per infected crab. There was a positive relationship between crab size and metacercarial density. Sequences of the second internal transcribed spacer region of the ribosomal RNA gene of the Paragonimus metacercariae obtained in this study were identical to those of Paragonimus mexicanus deposited in the DDBJ/EMBL/GenBank database. Thus, the present study is the first to confirm that the crab species H. guayaquilensis is the second intermediate host of P. mexicanus in Manabí Province, Ecuador. Because this crab might be the possible source of human infections in this area, residents should pay attention to improper crab-eating habits related with a neglected parasitic disease, i.e., paragonimiasis. PMID:29742874

The Crab pulsar at VHE

Directory of Open Access Journals (Sweden)

Zanin Roberta

2017-01-01

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

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.

Colour change and camouflage in juvenile shore crabs Carcinus maenas

Directory of Open Access Journals (Sweden)

Martin eStevens

2014-05-01

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

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

OpenAIRE

Bednarek, W.; Protheroe, R. J.

1997-01-01

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

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 ...

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.

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

Science.gov (United States)

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

2018-01-01

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

Intraguild predation by shore crabs affects mortality, behavior, growth, and densities of California horn snails

Science.gov (United States)

Lorda, J.; Hechinger, R.F.; Cooper, S. D.; Kuris, A. M.; Lafferty, Kevin D.

2016-01-01

The California horn snail, Cerithideopsis californica, and the shore crabs, Pachygrapsus crassipesand Hemigrapsus oregonensis, compete for epibenthic microalgae, but the crabs also eat snails. Such intraguild predation is common in nature, despite models predicting instability. Using a series of manipulations and field surveys, we examined intraguild predation from several angles, including the effects of stage-dependent predation along with direct consumptive and nonconsumptive predator effects on intraguild prey. In the laboratory, we found that crabs fed on macroalgae, snail eggs, and snails, and the size of consumed snails increased with predator crab size. In field experiments, snails grew less in the presence of crabs partially because snails behaved differently and were buried in the sediment (nonconsumptive effects). Consistent with these results, crab and snail abundances were negatively correlated in three field surveys conducted at three different spatial scales in estuaries of California, Baja California, and Baja California Sur: (1) among 61 sites spanning multiple habitat types in three estuaries, (2) among the habitats of 13 estuaries, and (3) among 34 tidal creek sites in one estuary. These results indicate that shore crabs are intraguild predators on California horn snails that affect snail populations via predation and by influencing snail behavior and performance.

Present and Potential Future Distributions of Asian Horseshoe Crabs Determine Areas for Conservation

Directory of Open Access Journals (Sweden)

Stine Vestbo

2018-05-01

Full Text Available Conservation of horseshoe crabs has recently received increasing attention as several populations are in decline. However, scarce information on their distributions in Southeast Asia is impairing conservation efforts. In this study, we sought to improve our understanding of the geographical range and distinct populations of the three Asian horseshoe crabs species in order to identify optimal conservation areas. We mapped the geographic range of Carcinoscorpius rotundicauda, Tachypleus gigas, and T. tridentatus using recent data from field work, literature, Global Biodiversity Information Facility (GBIF, and unpublished data from our scientific network. The data were correlated with 23 different environmental variables of potential ecological importance for horseshoe crabs using the openModeller webservices, including new tidal variables. Ecological niche models were generated using two algorithms, Maximum Entropy and support vector machine, for the three species under present conditions, and projected into a climate change scenario of 2050. The niches of the Asian horseshoe crabs were mostly determined by tidal regime, chlorophyll A concentrations, depth, distance to land, and sea surface temperature. According to our predictions, horseshoe crabs in Southeast Asia are not expected to experience any severe change in extent and distribution of suitable habitat in the future. In order to conserve Asian horseshoe crabs, we suggest establishing Marine Protected Areas at locations where distinct populations and several species occur, such as northern Vietnam, China, Borneo, and southern Japan.

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

International Nuclear Information System (INIS)

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

1982-01-01

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

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

DEFF Research Database (Denmark)

Dunn, Paul; Shanks, Alan

2012-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-08-01

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

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

African Journals Online (AJOL)

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

Effects of fenoxycarb exposure on complete larval development of the xanthid crab, Rhithropanopeus harrisii

International Nuclear Information System (INIS)

Cripe, G.M.; McKenney, C.L.; Hoglund, M.D.; Harris, P.S.

2003-01-01

The pest control agent fenoxycarb reduced survival and extended duration of developing larval stages in the xanthid crab, Rhithropanopeus harrisii. - Pest control agents, such as juvenile hormone analogues (JHA), have been developed to limit effects on non-target organisms that co-inhabit insect pest habitats. Rhithropanopeus harrisii, an estuarine xanthid crab, was used to observe the impacts of the JHA, fenoxycarb, on the pattern of complete larval development as well as survival of larvae and successful metamorphosis to first crab stage. Significant mortality occurred in the first of four zoeal stages (after 2-3 days of exposure) at the highest treatment of 240 μg fenoxycarb/l and in megalopae exposed to 48 μg fenoxycarb/l. The time required to metamorphose to the first crab stage was significantly increased for megalopae in all treatments ≥48 μg/l. This delay in development was sufficient to significantly prolong the entire developmental period from zoea to crabs. Unexposed larvae developed to crabs in an average of 16 days; larvae exposed to ≥48 μg/l required 19-20 days. Reduced survival and extended duration of developing larval stages in the life history of a benthic invertebrate may alter the population dynamics of these organisms in the estuary

Effects of fenoxycarb exposure on complete larval development of the xanthid crab, Rhithropanopeus harrisii

Energy Technology Data Exchange (ETDEWEB)

Cripe, G.M.; McKenney, C.L.; Hoglund, M.D.; Harris, P.S

2003-09-01

The pest control agent fenoxycarb reduced survival and extended duration of developing larval stages in the xanthid crab, Rhithropanopeus harrisii. - Pest control agents, such as juvenile hormone analogues (JHA), have been developed to limit effects on non-target organisms that co-inhabit insect pest habitats. Rhithropanopeus harrisii, an estuarine xanthid crab, was used to observe the impacts of the JHA, fenoxycarb, on the pattern of complete larval development as well as survival of larvae and successful metamorphosis to first crab stage. Significant mortality occurred in the first of four zoeal stages (after 2-3 days of exposure) at the highest treatment of 240 {mu}g fenoxycarb/l and in megalopae exposed to 48 {mu}g fenoxycarb/l. The time required to metamorphose to the first crab stage was significantly increased for megalopae in all treatments {>=}48 {mu}g/l. This delay in development was sufficient to significantly prolong the entire developmental period from zoea to crabs. Unexposed larvae developed to crabs in an average of 16 days; larvae exposed to {>=}48 {mu}g/l required 19-20 days. Reduced survival and extended duration of developing larval stages in the life history of a benthic invertebrate may alter the population dynamics of these organisms in the estuary.

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

Digital Repository Service at National Institute of Oceanography (India)

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

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

Impacts of Habitat Complexity on Physiology: Purple Shore Crabs Tolerate Osmotic Stress for Shelter

Science.gov (United States)

McGaw, I. J.

2001-12-01

Purple shore crabs, Hemigrapsus nudus (Crustacea: Decapoda), can survive indefinitely in salinities of 8 (25% SW), but also tolerate short-term exposure to salinities as low as 2. In the laboratory their salinity preference range, determined from choice chamber experiments, is 22-32 and they can discriminate between pairs of salinities separated by a difference of 2. These crabs show a strong positive thigmotaxis and a weak negative phototaxis and tend to choose environments with available shelter. The presence of shelter significantly alters the behaviour of this species. When shelter is available the salinity preference range is 10-32. Even in salinities below this preference range, the presence of shelter prolongs the time spent in the lower test salinities. This change in behaviour has implications on the crab's physiology: the haemolymph osmolality falls to lower levels when crabs remain in low salinity under shelters. In the field, H. nudus is found in creeks with salinities close to freshwater and they may remain in this salinity for up to 11 h, if there are rocks under which to shelter. An increase in habitat complexity increases the number of crabs that are found within the creek. These crabs in the low salinity environment have a lower haemolymph osmolality than crabs on the nearby open shore. In H. nudus the behavioural selection of a shelter appears to outweigh the physiological costs associated with osmotic regulation of the body fluids. Therefore, the distribution of H. nudus in estuaries may depend more on the availability of suitable habitats rather than the salinity tolerance of this species.

Trophic discrimination of stable isotopes and potential food source partitioning by leaf-eating crabs in mangrove environments

DEFF Research Database (Denmark)

Kristensen, Erik; Lee, Shing Yip; Mangion, Perrine

2017-01-01

Diet composition of leaf-eating mangrove crabs is a puzzle among mangrove ecologists. Nutrient-poor leaf litter can in most cases not support animal growth. Food partitioning (mangrove leaves, animal tissue, and microphytobenthos [MPB]) of sesarmid and ucidid mangrove crabs from eight locations...... here for crabs foraging on leaf litter to identify discrimination values that provide a balanced diet with sufficient nutrients (i.e., N) when combined with other food sources. The data from all mangrove locations suggest that sesarmid and ucidid crabs ingest and assimilate mixtures of available food...... is probably caused by metabolic disparities between these two crab families. Deviations in 15N discrimination have in most cases only minor influence on the model-based 13C discrimination thresholds. The present findings lead us to suggest a modified Optimal Foraging Theory for leaf-eating mangrove crabs....

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.

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.

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

Ethnotaxonomical Study of Mole Crab (Crustacea:Hippoidea on Coastal Community of Cilacap

Directory of Open Access Journals (Sweden)

Dian Bhagawati

2016-09-01

Full Text Available Local wisdom is a cultural heritage that needs to be preserved. The Cilacap’s coastal communities have traditional taxonomy knowledge that hasn’t been informed, especially about mole crab. This study aimed to explore the ethnotaxonomy knowledge of sand crabs (Crustacea: Hippoidea in Widarapayung coastal communities. The purposive snowball sampling was used for the method, followed by observation and semi-structured interviews with 30 respondents. Data were analyzed descriptively based on observations and interviews. The results showed that the coastal communities in Widarapayung tourist areas could be divided into five groups, namely catchers, collectors, processors, traders, and consumers. The catcher was able to recognize and describe three types of sand crabs based on the shape of the body and their catchment areas. Captured crabs had the local name of ‘yutuk jambe’ (Emerita emeritus Linnaeus 1767, the appellation was based on carapace shape that resembled the shape of areca fruit; ‘Yutuk bathok’ (Hippa adactyla Fabricius 1787, had the carapace shape resembling a coconut shell, and ‘yutuk Kethek’ (Albunea symmysta Linnaeus 1758, had ornaments on the carapace surface similar with a monkey face, there were dense setae on the edge of the carapace, spiny long antennas and aggressively pinch when captured. The knowledge and skills of sand crabs classification and local name entitlement acquired by the people were in accordance with the Berlin’s model. How to CiteBhagawati, D., Anggoro, S., Zainuri, M. & Sya’rani, L. (2016. Ethnotaxonomical Study of Mole Crab (Crustacea:Hippoidea on Coastal Community of Cilacap. Biosaintifika: Journal of Biology & Biology Education, 8(2, 222-230.

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

Science.gov (United States)

2011-06-22

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

Dicty_cDB: Contig-U01447-1 [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available elium discoideum slug cDNA, clone SSG388. 48 0.15 1 ( CV463052 ) CS_hyp_52b08_M13Reverse Blue crab hypoder... 46 0.61 1 ( CV162186 ) CS_hyp_01d11_M13Reverse Blue crab hypodermis, nor... 46 0.61 1 ( CF837135 ) UCRCS03_

Sterol biosynthesis from acetate and the fate of dietary cholesterol and desmosterol in crabs

International Nuclear Information System (INIS)

Teshima, Shin-ichi; Kanazawa, Akio; Okamoto, Haruhito

1976-01-01

This paper deals with the sterol-synthesizing ability and the fate of dietary sterols, cholesterol and desmosterol, in the crabs, Sesarma dehaani and Helice tridens. Injected acetate-1- 14 C was not incorporated into either squalene or sterols in the above crabs. This suggested that the sterol-synthesizing ability from acetate is absent or weak in the crabs, S. dehaani and H. tridens. The apparent percentage absorptions of dietary cholesterol and desmosterol from the digestive tracts were 91.9 and 90.9, respectively. The ingested cholesterol and desmosterol were metabolized to steryl esters and polar compounds but only slightly to water-soluble sterols. Also, it was shown that the crab, S. dehaani, is capable of converting desmosterol to cholesterol. (auth.)

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

Science.gov (United States)

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

1988-01-01

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

Infection of juvenile edible crabs, Cancer pagurus by a haplosporidian-like parasite.

Science.gov (United States)

Thrupp, Tara J; Lynch, Sharon A; Wootton, Emma C; Malham, Shelagh K; Vogan, Claire L; Culloty, Sarah C; Rowley, Andrew F

2013-09-01

This study aimed to examine the pathobiology of a haplosporidian-like infection in juvenile (pre-recruit) edible crabs (Cancer pagurus) from two locations in South West Wales, UK. Infected crabs showed no external symptoms of the disease but dissection revealed an infected and hypertrophic antennal gland. Histological examination showed extensive parasitisation of the antennal gland overlying the hepatopancreas. Heavily infected crabs also showed the presence of parasites with morphological similarities to Haplosporidia in the labyrinth of the antennal gland and in the gills. The spread of the infection from the antennal gland to the gills suggests that these parasites are released into the haemolymph. Attempts to characterise the haplosporidian-like organism using several primers previously shown to amplify members of the phylum Haplosporidia failed. The prevalence of infection in juvenile edible crabs varied throughout the sampling period of November 2011 to July 2012 with the lowest level of ca. 15% in November peaking at 70% in March. This parasite may represent a threat to the sustainability of edible crab fisheries in this region if the damage observed in the antennal gland and gills results in host mortality. The identification of these parasites as members of the phylum Haplosporidia based on morphology alone must be seen as tentative in the absence of sequence data. Copyright © 2013 Elsevier Inc. All rights reserved.

Spatial and temporal patterns of subtidal and intertidal crabs excursions

Science.gov (United States)

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

2014-01-01

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

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...

Dicty_cDB: Contig-U16102-1 [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available 0 6 ( BJ408668 ) Dictyostelium discoideum cDNA clone:dds46g14, 3' ... 44 3.0 2 ( CV162186 ) CS_hyp_01d11_M13Reverse Blue crab hypoder...08_M13Reverse Blue crab hypodermis, nor... 42 3.6 2 ( AM474408 ) Vitis vinifera contig VV78X173370.5, whole

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

Science.gov (United States)

2010-02-19

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

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

NARCIS (Netherlands)

Scholtz, G.

2014-01-01

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

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.

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.

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.

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.

Dominance and population structure of freshwater crabs ...

African Journals Online (AJOL)

1997-02-06

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

Modelling the ArH+ emission from the Crab nebula

Science.gov (United States)

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

2017-12-01

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

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

International Nuclear Information System (INIS)

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

2010-01-01

Measuring the levels of the major airborne allergens of snow crab in the workplace is very important in studying the prevalence of crab asthma in workers. Previously, snow crab tropomyosin (SCTM) was identified as the major aeroallergen in crab plants and a unique signature peptide was identified for this protein. The present study advances our knowledge on aeroallergens by developing a method of quantification of airborne SCTM by using isotope dilution mass spectrometry. Liquid chromatography tandem mass spectrometry was developed for separation and analysis of the signature peptides. The tryptic digestion conditions were optimized to accomplish complete digestion. The validity of the method was studied using international conference on harmonization protocol, Where 2-9% for CV (precision) and 101-110% for accuracy, at three different levels of quality control. Recovery of the spiked protein from PTFE and TopTip filters was measured to be 99% and 96%, respectively. To further demonstrate the applicability and the validity of the method for real samples, 45 kg of whole snow crab were processed in an enclosed (simulated) crab processing line and air samples were collected. The levels of SCTM ranged between 0.36-3.92 μg m -3 and 1.70-2.31 μg m -3 for butchering and cooking stations, respectively.

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

Energy Technology Data Exchange (ETDEWEB)

Rahman, Anas M. Abdel, E-mail: anasar@mun.ca [Department of Chemistry, Memorial University of Newfoundland, St. John' s, Newfoundland A1B 3X7 (Canada); Lopata, Andreas L. [School of Applied Science, Marine Biomedical Sciences and Health Research Group, RMIT University, Bundoora, 3083 Victoria (Australia); Randell, Edward W. [Department of Laboratory Medicine, Memorial University of Newfoundland, Eastern Health, St. John' s, Newfoundland and Labrador A1B 3V6 (Canada); Helleur, Robert J. [Department of Chemistry, Memorial University of Newfoundland, St. John' s, Newfoundland A1B 3X7 (Canada)

2010-11-29

Measuring the levels of the major airborne allergens of snow crab in the workplace is very important in studying the prevalence of crab asthma in workers. Previously, snow crab tropomyosin (SCTM) was identified as the major aeroallergen in crab plants and a unique signature peptide was identified for this protein. The present study advances our knowledge on aeroallergens by developing a method of quantification of airborne SCTM by using isotope dilution mass spectrometry. Liquid chromatography tandem mass spectrometry was developed for separation and analysis of the signature peptides. The tryptic digestion conditions were optimized to accomplish complete digestion. The validity of the method was studied using international conference on harmonization protocol, Where 2-9% for CV (precision) and 101-110% for accuracy, at three different levels of quality control. Recovery of the spiked protein from PTFE and TopTip filters was measured to be 99% and 96%, respectively. To further demonstrate the applicability and the validity of the method for real samples, 45 kg of whole snow crab were processed in an enclosed (simulated) crab processing line and air samples were collected. The levels of SCTM ranged between 0.36-3.92 {mu}g m{sup -3} and 1.70-2.31 {mu}g m{sup -3} for butchering and cooking stations, respectively.

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

Energy Technology Data Exchange (ETDEWEB)

Hui, Clifford A. [US Geological Survey, 7801 Folsom Blvd, Suite 101, Sacramento, CA 95826 (United States)]. E-mail: bioinvestigations@sbcglobal.net; Rudnick, Deborah [Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720 (United States); Williams, Erin [US Fish and Wildlife Service, 4001 N. Wilson Way, Stockton, CA 95205 (United States)

2005-02-01

Chinese mitten crabs (Eriocheir sinensis), endemic to Asia, were first reported in the San Francisco Bay in 1992. They are now established in nearly all San Francisco Bay tributaries. These crabs accumulate more metals, such as mercury, than crustaceans living in the water column. Because their predators include fish, birds, mammals and humans, their mercury burdens have an exceptional potential to impact the ecosystem and public health. We sought to elucidate the potential threat of mitten crab mercury burdens in three adjacent streams in southern San Francisco Bay, one of which is known to be contaminated with mercury. Mitten crabs had hepatopancreas concentrations of total mercury and methylmercury that did not differ among streams. The maximum burden we measured was below the action level of 1 ppm recommended by the USEPA. Hepatopancreas concentrations of methylmercury declined with increasing crab size, suggesting a mechanism for mercury excretion and that predators might reduce mercury exposure if they select larger crabs. Because mercury may be heterogeneously distributed among tissues, estimation of the impacts of crab mercury burdens on the environment requires more data on the feeding preferences of predators. - Hepatopancreas concentrations of mercury decline with crab size, which may have important consequences for bio-magnification in food webs.

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

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

Science.gov (United States)

2010-08-13

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

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...

Prevalence and antimicrobial susceptibility of Vibrio parahaemolyticus isolated from seafoods in Lagos Lagoon Nigeria

Directory of Open Access Journals (Sweden)

Chigozie Oramadike

2015-12-01

Full Text Available In this study, a total of 90 seafood samples; croaker fish (Pseudotolithus senegalensis, shrimps (Penaeus notialis and blue crab (Callinectes sapidus collected from landing sites along the Lagos Lagoon in Nigeria were examined for the prevalence of Vibrio parahaemolyticus using both biochemical and molecular methods. Biochemical identification of the isolates was confirmed by Polymerase Chain Reaction (PCR. The presence of the virulence-associated tdh (thermostable direct haemolysin, trh1 (thermostable-related haemolysin and trh2 genes in the V. parahaemolyticus isolates was also detected by the PCR method. PCR products from the V.16S primers were sequenced. Antibiotics susceptibility of the isolates was also determined. About, eight isolates were presumptively identified as V. parahaemolyticus, PCR identified five and none of the isolates were positive for the genes tdh or trh. The five isolates sequenced were identified as different strains of V. parahaemolyticus. V. parahaemolyticus_RIMD_2210633 = 2MKSHa remained resistant to all antimicrobials tested. However, only V. parahaemolyticus_MP-2_AY911391 = TBSHy showed strong sensitivity to all the antimicrobials with ampicillin (minimum inhibitory concentration-4 μg/ml. In addition, the other three isolates showed sensitivity for Tetracycline, Ciprofloxacin, Gentamicin and Ceftazidime. Ampicillin resistance in most of the isolates suggests low efficiency of ampicillin in management of V. parahaemolyticus infection.

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

Science.gov (United States)

2010-06-22

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

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.

Characterization of microRNAs in Mud Crab Scylla paramamosain under Vibrio parahaemolyticus Infection

Science.gov (United States)

Li, Chuanbiao; Zhang, Zhao; Zhou, Lizhen; Wang, Shijia; Wang, Shuqi; Zhang, Yueling; Wen, Xiaobo

2013-01-01

Background Infection of bacterial Vibrio parahaemolyticus is common in mud crab farms. However, the mechanisms of the crab’s response to pathogenic V. parahaemolyticus infection are not fully understood. MicroRNAs (miRNAs) are a class of small noncoding RNAs that function as regulators of gene expression and play essential roles in various biological processes. To understand the underlying mechanisms of the molecular immune response of the crab to the pathogens, high-throughput Illumina/Solexa deep sequencing technology was used to investigate the expression profiles of miRNAs in S . paramamosain under V. parahaemolyticus infection. Methodology/Principal Findings Two mixed RNA pools of 7 tissues (intestine, heart, liver, gill, brain, muscle and blood) were obtained from V. parahaemolyticus infected crabs and the control groups, respectively. By aligning the sequencing data with known miRNAs, we characterized 421 miRNA families, and 133 conserved miRNA families in mud crab S . paramamosain were either identical or very similar to existing miRNAs in miRBase. Stem-loop qRT-PCRs were used to scan the expression levels of four randomly chosen differentially expressed miRNAs and tissue distribution. Eight novel potential miRNAs were confirmed by qRT-PCR analysis and the precursors of these novel miRNAs were verified by PCR amplification, cloning and sequencing in S . paramamosain . 161 miRNAs (106 of which up-regulated and 55 down-regulated) were significantly differentially expressed during the challenge and the potential targets of these differentially expressed miRNAs were predicted. Furthermore, we demonstrated evolutionary conservation of mud crab miRNAs in the animal evolution process. Conclusions/Significance In this study, a large number of miRNAs were identified in S . paramamosain when challenged with V. parahaemolyticus, some of which were differentially expressed. The results show that miRNAs might play some important roles in regulating gene expression in

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

Science.gov (United States)

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

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...

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.

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.

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

Science.gov (United States)

2011-07-06

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

The Effect of Different Feed and Stocking Densities on Growth And Survival Rate Of Blue Swimming Crablets (Portunus pelagicus)

Science.gov (United States)

Ariyati, R. W.; Rejeki, S.; Bosma, R. H.

2018-02-01

Blue swimming crab is targeted by commercial fisheries because of the high economic value, good taste, and attractive colors. As a result, the stock is overexploited and fisherman catch market also juveniles. The most sustainable solution would be to stop fishing for commercial trade and to culture this crab from brood to market size. This study aimed to find the best feed and stocking density for the on-growing of crablets. In 20 tanks juvenile crabs with a carapace width±1 cm were stocked in three densities; 40, 60 and 80 crablets / m2, and fed ad-libitum twice a day with either trash fish or pellets of shrimp feed, for 8 weeks. The circular (ᴓ 1.6 m x 1 m) tanks with 1 m3 of water were aerated, and temperature, salinity, dissolved oxygen and pH recorded daily. In the end, growth and survival rates were determined. In general, feeding the crablets at a density of 40 m-2 gave the highest growth. For crablest fed with pellets, the density of 40 m-2 gave significantly better growth than 80 m-2. The crablets at a density 40 m-2 having a fish diet with the density 40 m-2 grew better than 60 and 80 m-2. There was no significant difference between fed used among different densities. The lower densities resulted in higher survival, either on crablets fed with pellets or fish. But, crablets fed the fish diet and cultured in the lowest density (40 m-2) had the highest survival rate.

Study with one global crab cavity at IR4 for LHC Upgrade

CERN Document Server

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

2009-01-01

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

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

Digital Repository Service at National Institute of Oceanography (India)

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

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

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.

Crab Flares and Magnetic Reconnection in Pulsar Winds

Science.gov (United States)

Harding, Alice K.

2012-01-01

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

Enhancement of the immune response and protection against Vibrio parahaemolyticus by indigenous probiotic Bacillus strains in mud crab (Scylla paramamosain).

Science.gov (United States)

Wu, Hui-Juan; Sun, Ling-Bin; Li, Chuan-Biao; Li, Zhong-Zhen; Zhang, Zhao; Wen, Xiao-Bo; Hu, Zhong; Zhang, Yue-Ling; Li, Sheng-Kang

2014-12-01

In a previous study, bacterial communities of the intestine in three populations of crabs (wild crabs, pond-raised healthy crabs and diseased crabs) were probed by culture-independent methods. In this study, we examined the intestinal communities of the crabs by bacterial cultivation with a variety of media. A total of 135 bacterial strains were isolated from three populations of mud crabs. The strains were screened for antagonistic activity against Vibrio parahaemolyticus using an agar spot assay. Antagonistic strains were then identified by 16S rRNA gene sequence analysis. Three strains (Bacillus subtilis DCU, Bacillus pumilus BP, Bacillus cereus HL7) with the strongest antagonistic activity were further evaluated for their probiotic characteristics. The results showed that two (BP and DCU) of them were able to survive low pH and high bile concentrations, showed good adherence characteristics and a broad spectrum of antibiotic resistance. The probiotic effects were then tested by feeding juvenile mud crabs (Scylla paramamosain) with foods supplemented with 10(5) CFU/g of BP or DCU for 30 days before being subjected to an immersion challenge with V. parahaemolyticus for 48 h. The treated crabs showed significantly higher expression levels of immune related genes (CAT, proPO and SOD) and activities of respiratory burst than that in controlled groups. Crabs treated with BP and DCU supplemented diets exhibited survival rates of 76.67% and 78.33%, respectively, whereas survival rate was 54.88% in crabs not treated with the probiotics. The data showed that indigenous mud-associated microbiota, such as DCU and BP, have potential application in controlling pathogenic Vibriosis in mud crab aquaculture. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

Science.gov (United States)

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

2007-03-01

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

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 ...

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.

[Spectral sensitivity and visual pigments of the coastal crab Hemigrapsus sanguineus].

Science.gov (United States)

Shukoliukov, S A; Zak, P P; Kalamkarov, G R; Kalishevich, O O; Ostrovskiĭ, M A

1980-01-01

It has been shown that the compound eye of the coastal crab has one photosensitive pigment rhodopsin and screening pigments, black and orange one. The orange pigment has lambda max = 480 nm, rhodopsin in digitonin is stable towards hydroxylamin action, has lambda max = 490-495 nm and after bleaching is transformed into free retinene and opsin. The pigments with lambda max = 430 and 475 nm of the receptor part of the eye are also solubilized. These pigments are not photosensitive but they dissociate under the effect of hydroxylamine. The curye of spectral sensitivity of the coastal crab has the basic maximum at approximately 525 nm and the additional one at 450 nm, which seems to be provided by a combination of the visual pigment--rhodopsin (lambda max 500 nm) with a carotinoid filter (lambda max 480-490). Specific features of the visual system of coastal crab are discussed.

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.

Development of the male reproductive system in Callinectes ornatus Ordway, 1863 (Brachyura: Portunidae

Directory of Open Access Journals (Sweden)

Fabiana Aparecida do Nascimento

Full Text Available This study describes the histology and histochemistry of the male reproductive system in Callinectes ornatus, comparing juvenile and adult developmental stages. We also analyzed changes in the gonadosomatic (GSI and hepatosomatic (HSI indices, and the weights of the testis and vas deferens during the development. The results showed that all stages, beginning with the juvenile (JUV, through developing (DEV and mature (MAT adult males of C. ornatus produce sperm and spermatophores. During development, testicular lobes showed the same characteristics of production and release of sperm into the seminiferous duct. The vas deferens showed little histological and histochemical change in the epithelium in juvenile and adult males. The differences consisted of the larger amount of secretion in MAT males compared to JUV and DEV ones. The chemical composition of the seminal fluid was similar, but MAT males produced a more homogeneous secretion. Morphological and physiological maturation are not synchronized in C. ornatus, since JUV males produced spermatophores similar to those in DEV and MAT males. However, these JUV are not yet able to reproduce, since they still have the abdomen attached to the cephalothoracic sternum. The increase of the GSI during development was significant for MAT males, and is related to the production of sufficient volume of seminal fluid to form the sperm "plug" in the female seminal receptacle. The HSI decreased from DEV to MAT adult stages, indicating that reserves from the hepatopancreas are used to develop the reproductive system after the pubertal molt.

Increase in density of genetically diverse invasive Asian shore crab (Hemigrapsus sanguineus) populations in the Gulf of Maine.

Science.gov (United States)

Lord, Joshua P; Williams, Larissa M

2017-04-01

Hemigrapsus sanguineus , the Asian shore crab, has rapidly replaced Carcinus maenas , the green crab, as the most abundant crab on rocky shores in the northwest Atlantic since its introduction to the United States (USA) in 1988. The northern edge of this progressing invasion is the Gulf of Maine, where Asian shore crabs are only abundant in the south. We compared H. sanguineus population densities to those from published 2005 surveys and quantified genetic variation using the cytochrome c oxidase subunit I gene. We found that the range of H. sanguineus had extended northward since 2005, that population density had increased substantially (at least 10-fold at all sites), and that Asian shore crabs had become the dominant intertidal crab species in New Hampshire and southern Maine. Despite the significant increase in population density of H. sanguineus , populations only increased by a factor of 14 in Maine compared to 70 in southern New England, possibly due to cooler temperatures in the Gulf of Maine. Genetically, populations were predominantly composed of a single haplotype of Japanese, Korean, or Taiwanese origin, although an additional seven haplotypes were found. Six of these haplotypes were of Asian origin, while two are newly described. Large increases in population sizes of genetically diverse individuals in Maine will likely have a large ecological impact, causing a reduction in populations of mussels, barnacles, snails, and other crabs, similar to what has occurred at southern sites with large populations of this invasive crab species.

FACT. Energy spectrum of the Crab Nebula

Energy Technology Data Exchange (ETDEWEB)

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

2016-07-01

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

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

Ontogenetic scaling of the olfactory antennae and flicking behavior of the shore crab, Hemigrapsus oregonensis.

Science.gov (United States)

Waldrop, Lindsay D

2013-07-01

Malacostracan crustaceans such as crabs flick antennae with arrays of olfactory sensilla called aesthetascs through the water to sense odors. Flicking by crabs consists of a quick downstroke, in which aesthetascs are deflected laterally (splayed), and a slower, reversed return stroke, in which aesthetascs clump together. This motion causes water to be flushed within and then held in between aesthetascs to deliver odor molecules to olfactory receptors. Although this odor sampling method relies on a narrow range of speeds, sizes, and specific arrangements of aesthetascs, most crabs dramatically change these during ontogeny. In this study, the morphometrics of the aesthetascs, array, and antennae and the flicking kinematics of the Oregon shore crab, Hemigrapsus oregonensis (Decapoda: Brachyura), are examined to determine their scaling relationships during ontogeny. The morphometrics of the array and antennae increase more slowly than would be predicted by isometry. Juvenile crabs' aesthetascs splay relatively further apart than adults, likely due to changing material properties of aesthetasc cuticle during growth. These results suggest that disproportionate growth and altered aesthetasc splay during flicking will mediate the size changes due to growth that would otherwise lead to a loss of function.

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.

Preference alters consumptive effects of predators: top-down effects of a native crab on a system of native and introduced prey.

Directory of Open Access Journals (Sweden)

Emily W Grason

Full Text Available Top-down effects of predators in systems depend on the rate at which predators consume prey, and on predator preferences among available prey. In invaded communities, these parameters might be difficult to predict because ecological relationships are typically evolutionarily novel. We examined feeding rates and preferences of a crab native to the Pacific Northwest, Cancer productus, among four prey items: two invasive species of oyster drill (the marine whelks Urosalpinx cinerea and Ocenebra inornata and two species of oyster (Crassostrea gigas and Ostrea lurida that are also consumed by U. cinerea and O. inornata. This system is also characterized by intraguild predation because crabs are predators of drills and compete with them for prey (oysters. When only the oysters were offered, crabs did not express a preference and consumed approximately 9 juvenile oysters crab(-1 day(-1. We then tested whether crabs preferred adult drills of either U. cinerea or O. inornata, or juvenile oysters (C. gigas. While crabs consumed drills and oysters at approximately the same rate when only one type of prey was offered, they expressed a strong preference for juvenile oysters over drills when they were allowed to choose among the three prey items. This preference for oysters might negate the positive indirect effects that crabs have on oysters by crabs consuming drills (trophic cascade because crabs have a large negative direct effect on oysters when crabs, oysters, and drills co-occur.

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.

Sea turtle symbiosis facilitates social monogamy in oceanic crabs via refuge size.

Science.gov (United States)

Pfaller, Joseph B; Gil, Michael A

2016-09-01

The capacity for resource monopolization by individuals often dictates the size and composition of animal groups, and ultimately, the adoption of mating strategies. For refuge-dwelling animals, the ability (or inability) of individuals to monopolize refuges should depend on the relative size of the refuge. In theory, groups should be larger and more inclusive when refuges are large, and smaller and more exclusive when refuges are small, regardless of refuge type. We test this prediction by comparing the size and composition of groups of oceanic crabs (Planes minutus) living on plastic flotsam and loggerhead sea turtles. We found that (i) surface area of refuges (barnacle colonies on flotsam and supracaudal space on turtles) is a better predictor of crab number than total surface area and (ii) flotsam and turtles with similar refuge surface area host a similar number (1-2) and composition (adult male-female pairs) of crabs. These results indicate that group size and composition of refuge-dwelling animals are modulated by refuge size and the capacity for refuge monopolization. Moreover, these results suggest that sea turtle symbiosis facilitates social monogamy in oceanic crabs, providing insights into how symbiosis can promote specific mating strategies. © 2016 The Author(s).

Scaled laboratory experiments explain the kink behaviour of the Crab Nebula jet.

Science.gov (United States)

Li, C K; Tzeferacos, P; Lamb, D; Gregori, G; Norreys, P A; Rosenberg, M J; Follett, R K; Froula, D H; Koenig, M; Seguin, F H; Frenje, J A; Rinderknecht, H G; Sio, H; Zylstra, A B; Petrasso, R D; Amendt, P A; Park, H S; Remington, B A; Ryutov, D D; Wilks, S C; Betti, R; Frank, A; Hu, S X; Sangster, T C; Hartigan, P; Drake, R P; Kuranz, C C; Lebedev, S V; Woolsey, N C

2016-10-07

The remarkable discovery by the Chandra X-ray observatory that the Crab nebula's jet periodically changes direction provides a challenge to our understanding of astrophysical jet dynamics. It has been suggested that this phenomenon may be the consequence of magnetic fields and magnetohydrodynamic instabilities, but experimental demonstration in a controlled laboratory environment has remained elusive. Here we report experiments that use high-power lasers to create a plasma jet that can be directly compared with the Crab jet through well-defined physical scaling laws. The jet generates its own embedded toroidal magnetic fields; as it moves, plasma instabilities result in multiple deflections of the propagation direction, mimicking the kink behaviour of the Crab jet. The experiment is modelled with three-dimensional numerical simulations that show exactly how the instability develops and results in changes of direction of the jet.

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

Directory of Open Access Journals (Sweden)

Bradley J. Peterson

2014-07-01

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

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

Science.gov (United States)

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

2014-01-01

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

Reproductive biology of the Suez Canal spider crab Schizophrys aspera (H. Milne Edwards, 1834: Crustacea: Brachyura: Majidae).

Science.gov (United States)

El-Serehy, Hamed A; Al-Rasheid, Khaled A; Ibrahim, Nesreen K; Al-Misned, Fahad A

2015-11-01

A reproductive biology study of the spider crab Schizophrys aspera (H. Milne Edwards, 1834) was conducted in the Suez Canal from July 2012 to June 2013. The annual sex ratio (Male:Female) of S. aspera was female biased with values of 1:1.25. Out of the four ovarian development stages of this crab, two stages were observed in the Suez Canal throughout the whole year. The ovigerous crab's carapace width varied from 28 to 52 mm. This crab species can spawn during most of the year in the canal water, with a peak during late spring and early winter. The fecundity of ovigerous females ranged between 2349 and 13600 eggs with a mean of 5494 ± 1486 eggs. Female crabs that reached sexual maturity exhibited a minimum carapace width varying between 22 and 46 mm, and fifty percentage of all ovigerous females showed a carapace width of 36 mm.

Lung function and prevalence of respiratory symptoms in Norwegian crab processing workers

OpenAIRE

Thomassen, Marte Renate; Aasmoe, Lisbeth; Bang, Berit E.; Braaten, Tonje

2017-01-01

Source at http://dx.doi.org/10.1080/22423982.2017.1313513 Background: Seafood processing workers have an increased risk of developing occupational asthma. This has not been studied among Norwegian crab processing workers, nor has the respiratory health of exposed workers been compared to a control group. Objectives: Assessing the impact of working in the crab processing industry on workers ’ respiratory health. Design: A cross-sectional study of the respiratory health i...

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...

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.

Crab Pulsar Astrometry and Spin-Velocity Alignment

Science.gov (United States)

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

2009-01-01

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

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

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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.

Epibiotic community of the horseshoe crab Tachypleus gigas

Digital Repository Service at National Institute of Oceanography (India)

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

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

Osmotic and ionic regulation in shore crabs Carcinus maenas inhabiting a tidal estuary

Science.gov (United States)

Winkler, A.; Siebers, D.; Becker, W.

1988-03-01

Shore crabs Carcinus maenas were exposed to salinities fluctuating according to the natural tidal rhythm. To this end they were maintained in net cages positioned in the estuarine waters of the river Elbe. The cages were lifted every hour, and between 8 12 specimens were analyzed for hemolymph concentrations of Na, K, Ca, Mg, and osmolality. The results obtained were compared with the respective data measured in external brackish water. In addition, the specific activity of Na-K-ATPase in a posterior gill was determined. Hemolymph Na and Mg as well as branchial Na-K-ATPase were also determined in crabs collected in the North Sea and the Baltic. The results show that in C. maenas living in salinities fluctuating with the tides by approx. 15‰ S, Na, K and Ca were hyperregulated, and Mg was effectively hyporegulated. The concentrations of all hemolymph ions and the activity of the Na-K-ATPase were kept constant over the whole tidal cycle. In Baltic crabs, Na was effectively hyperregulated and gill Na-K-ATPase was significantly elevated by a factor of ca 2 when compared with North Sea crabs. It is suggested that long-term hyperregulation of Na in constant salinities results from an increased number of Na-K-ATPase molecules which may change by synthesis or degradation following salinity stress. Constant hemolymph levels of hyperregulated Na in crabs inhabiting fluctuating brackish water are accomplished by activation of existing Na-K-ATPase by low Na and inhibition by higher ambient concentrations.

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...

Antibiotics in Crab Ponds of Lake Guchenghu Basin, China: Occurrence, Temporal Variations, and Ecological Risks

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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.

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

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.

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.

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.

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

Nutrient Contents of the Freshwater Crab, Isolapotamon bauense from Sarawak, Malaysia (Borneo).

Science.gov (United States)

Grinang, Jongkar; Tyan, Pang Sing; Tuen, Andrew Alek; Das, Indraneil

2017-07-01

Data on nutrient contents of freshwater crabs are important for ecological studies and species conservation assessments, especially when the species concerned is threatened among others by habitat destruction and uncontrolled resources utilisation. Indeed comprehensive biological information is required to reconcile the needs between sustainable resources utilisation and conservation of the species. This study documents the nutrient contents of a freshwater crab, Isolapotamon bauense which is listed as 'Vulnerable' in the IUCN Red List of Threatened Species and also being harvested by local community for dietary supplement. Results show that muscles of the freshwater crab contain a substantial amount of nutrients in particular water content (male = 79.31 ± 2.30 %, female = 77.63 ± 0.56 %), protein (male = 77.47 ± 6.11 %, female = 63.28 ± 3.62 %), magnesium (male = 51.48 ± 16.10 mg/g, female = 39.73 ± 6.99 mg/g) and calcium (male = 25.50 ± 6.98 mg/g, female = 39.73 ± 6.99 mg/g). Means of nutrient contents between male and female crabs are not significantly different. It is estimated that an individual of I. bauense with weight range of 56-139 g contained on average of 0.35 ± 0.15 g of protein. Our estimation also shows that the number of individuals of the freshwater crab required to meet the recommended daily protein intakes of the community concerned is in the range 35-96 individuals for children, 130-188 individuals for adolescents, 171-179 individuals for men and 149-159 individuals for women. The results imply that harvesting of wild I. bauense as a source of protein supplement naturally may not be practical because of its relatively low population abundance, and conservation of the species for its ecological roles may thus be preferred.

2531-IJBCS-Article-Etchian Olivier Assoi

African Journals Online (AJOL)

hp

Herklots, 1851 (Crustacea, Brachyura, Gecarcinidae) from the estuarine region of the Comoe ... (or 'land-dwelling' crabs), based on the terrestrial habits shown by adults ...... composition, growth pattern and feeding habits of the blue crab, ...

Evolutionary morphology of the organ systems in squat lobsters and porcelain crabs (crustacea: Decapoda: Anomala): an insight into carcinization.

Science.gov (United States)

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

2015-01-01

Porcelain crabs (Porcellanidae) are one of three taxa within anomuran crustaceans (Anomala) which possess a crab-like body form. Curiously, these three lineages evolved this shape independently from true crabs (Brachyura) in the course of the evolutionary process termed carcinization. The entire pleon in porcelain crabs is flexed under the cephalothorax and the carapace is approximately as broad as long. Despite their crab-like habitus, porcelain crabs are phylogenetically nested within squat lobsters (Munidopsidae, Munididae, Galatheidae). With a pleon which is only partly flexed under the cephalothorax and a cephalothorax which is longer than it is broad, squat lobsters represent morphologically intermediate forms between lobster-like and crab-like body shapes. Carcinization has so far mostly been studied with respect to outer morphology; however, it is evident that internal anatomical features are influenced through this change of body shape too. In this paper, the situation in Galatheoidea is elucidated by adding more taxa to existing descriptions of the hemolymph vascular systems and associated structures and organs. Micro-computer tomography and 3D reconstruction provide new insights. Autapomorphic states of various internal anatomical characters are present in nearly all the studied species, also reflecting some degree of anatomical disparity found within Galatheoidea. The ventral vessel system of porcelain crabs differs distinctly from that of squat lobsters. The differences in question are coherent (i.e. structural dependent) with morphological transformations in the integument, such as the shortening of the sternal plastron, which evolved in the course of carcinization. Shifts in the gonads and the pleonal neuromeres are coherent with the loss of the caridoid escape reaction, which in turn is a consequence of carcinization. The arterial transformations, however, are minor compared to other instances of carcinization in anomuran crustaceans since the last

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

NARCIS (Netherlands)

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

2005-01-01

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

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

Science.gov (United States)

Lovely, Christina M; O'Connor, Nancy J; Judge, Michael L

2015-01-01

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 m(2) with 62 mm(2) 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.

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.

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.

Use of multiple chemical tracers to define habitat use of Indo-Pacific mangrove crab, Scylla serrata (Decapoda: Portunidae)

Science.gov (United States)

Demopoulos, A.W.J.; Cormier, N.; Ewel, K.C.; Fry, B.

2008-01-01

The mangrove or mud crab, Scylla serrata, is an important component of mangrove fisheries throughout the Indo-Pacific. Understanding crab diets and habitat use should assist in managing these fisheries and could provide additional justification for conservation of the mangrove ecosystem itself. We used multiple chemical tracers to test whether crab movements were restricted to local mangrove forests, or extended to include adjacent seagrass beds and reef flats. We sampled three mangrove forests on the island of Kosrae in the Federated States of Micronesia at Lelu Harbor, Okat River, and Utwe tidal channel. Samples of S. serrata and likely food sources were analyzed for stable carbon (??13C), nitrogen (??15N), and sulfur (??34S) isotopes. Scylla serrata tissues also were analyzed for phosphorus (P), cations (K, Ca, Mg, Na), and trace elements (Mn, Fe, Cu, Zn, and B). Discriminant analysis indicated that at least 87% of the crabs remain in each site as distinct populations. Crab stable isotope values indicated potential differences in habitat use within estuaries. Values for ??13C and ??34S in crabs from Okat and Utwe were low and similar to values expected from animals feeding within mangrove forests, e.g., feeding on infauna that had average ??13C values near -26.5???. In contrast, crabs from Lelu had higher ?? 13C and ??34S values, with average values of -21.8 and 7.8???, respectively. These higher isotope values are consistent with increased crab foraging on reef flats and seagrasses. Given that S. serrata have been observed feeding on adjacent reef and seagrass environments on Kosrae, it is likely that they move in and out of the mangroves for feeding. Isotope mixing model results support these conclusions, with the greatest mangrove ecosystem contribution to S. serrata diet occurring in the largest mangrove forests. Conserving larger island mangrove forests (> 1 km deep) appears to support crab foraging activities. ?? 2007 Coastal and Estuarine Research

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

Host sharing and host manipulation by larval helminths in shore crabs: cooperation or conflict?

Science.gov (United States)

Poulin, Robert; Nichol, Katherine; Latham, A David M

2003-04-01

Larval helminths of different species that share the same intermediate host and are transmitted by predation to the same definitive host may cooperate in their attempts to manipulate the behaviour of the intermediate host, while at the same time having conflicts of interests over the use of host resources. A few studies have indicated that intermediate hosts harbouring larval helminths have altered concentrations of neurotransmitters in their nervous system, and thus measuring levels of neurotransmitters in host brains could serve to assess the respective and combined effect of different helminth species on host behaviour. Here, we investigate potential cooperation and conflict among three helminths in two species of crab intermediate hosts. The acanthocephalan Profilicollis spp., the trematode Maritrema sp. and an acuariid nematode, all use Macrophthalmus hirtipes (Ocypodidae) as intermediate host, whereas Profilicollis and Maritrema also use Hemigrapsus crenulatus (Grapsidae). All three helminths mature inside gulls or other shore birds. There was a significant decrease in the mean volume of Profilicollis cystacanths as the intensity of infection by this parasite increased in H. crenulatus, the only host in which this was investigated; however, there was no measurable effect of other helminth species on the size of acanthocephalans, suggesting no interspecific conflict over resource use within crabs. There was, in contrast, evidence of a positive interspecific association between the two most common helminth species: numbers of Profilicollis and Maritrema were positively correlated among crabs, independently of crab size, in M. hirtipes but not H. crenulatus. More importantly, we found that the total number of larval helminths per crab correlated significantly, and negatively, with concentrations of serotonin in crab brains, again only in M. hirtipes; numbers of each parasite species separately did not covary in either crab species with serotonin or dopamine, the

Changes in the selection differential exerted on a marine snail during the ontogeny of a predatory shore crab.

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Pakes, D; Boulding, E G

2010-08-01

Empirical estimates of selection gradients caused by predators are common, yet no one has quantified how these estimates vary with predator ontogeny. We used logistic regression to investigate how selection on gastropod shell thickness changed with predator size. Only small and medium purple shore crabs (Hemigrapsus nudus) exerted a linear selection gradient for increased shell-thickness within a single population of the intertidal snail (Littorina subrotundata). The shape of the fitness function for shell thickness was confirmed to be linear for small and medium crabs but was humped for large male crabs, suggesting no directional selection. A second experiment using two prey species to amplify shell thickness differences established that the selection differential on adult snails decreased linearly as crab size increased. We observed differences in size distribution and sex ratios among three natural shore crab populations that may cause spatial and temporal variation in predator-mediated selection on local snail populations.

Response of mole crab, Emerita emeritus to the thermal effluents from the Madras Atomic Power Station at Kalpakkam

International Nuclear Information System (INIS)

Subramoniam, T.; Munuswamy, N.; Israel, Sunil; Sathish, R.; Venugopalan, V.P.

2007-01-01

Mole crabs belonging to the genus Emerita are exclusively inhabitants of exposed wave washed sandy beaches in certain temperate and tropical seas. Its sedentary adult life and a primitive filter-feeding behavior make this intertidal crab an excellent indicator species for monitoring anthropogenic impact. Hence, this sand crab has been used to determine the effect of elevated temperature (rT) arising out of the thermal effluent from the Madras Atomic Power Station (MAPS), Kalpakkam with special reference to the intertidal fauna. Since Emerita exhibits limited capacity to move from their place of habitation, an analysis of the population structure of Emerita emeritus in the Kalpakkam coast including the impacted and the adjoining control sandy beaches on either side of the mixing point in the vicinity of the power plant was done. The data indicate that in the impact zone having an elevated seawater temperature of <35 deg C, the crab is completely absent. However, as we move away from the impact zone, with normalization of seawater temperature, Emerita move to safer areas on either side of the impact zone. Thus, the extensive field data on the distribution of mole crabs indicated that population structure is affected by the thermal plume, although the shifting positions of the mixing point (caused by northerly and southerly long shore currents) allowed decolonization of Emerita due to transmigration in positions that were earlier mixing points. This paper also describes a complete larval development of Emerita emeritus in the laboratory. Different life stages of E. emeritus were subjected to various power plant stressors to determine their varying responses. The expression of heat shock protein (hsp) in the gill tissue of the adult crabs was also observed when the crabs were exposed to elevated temperatures (35 deg C). However, no expression of heat shock proteins was observed when the crabs were subjected to chlorine stress. (author)

Fish kairomones induce spine elongation and reduce predation in marine crab larvae.

Science.gov (United States)

Charpentier, Corie L; Wright, Alexander J; Cohen, Jonathan H

2017-08-01

Specialized defense strategies are induced in zooplankton upon detection of predator chemical cues or kairomones. These defenses are well-described for freshwater zooplankters, with morphological defenses being particularly striking, but few studies have reported kairomone-induced morphological defenses in marine zooplankton. Here, we compare morphological responses to kairomones in the larvae of two marine crab species, estuarine mud crabs (Rhithropanopeus harrisii) and Asian shore crabs (Hemigrapsus sanguineus). When reared in the presence of fish kairomones, spine length increased by 2-3% in larval R. harrisii, while no morphological changes were identified in H. sanguineus. In subsequent feeding assays with a co-occurring fish predator (Atlantic silversides, Menidia menidia), consumption of R. harrisii was lower on larvae that had been reared with kairomones. In addition, we found that broods with smaller larvae are more likely to exhibit increases in spine length after kairomone exposure. Hence, the observed morphological response is likely influenced by larval size. © 2017 by the Ecological Society of America.

Burying behaviour of two sympatric crab species: Cancer magister and Cancer productus

Directory of Open Access Journals (Sweden)

Iain J. McGaw

2005-09-01

Full Text Available The mechanics and emergence patterns associated with burying behaviour were investigated in the Dungeness crab, Cancer magister, and the red rock crab, Cancer productus. Cancer magister used both the legs and chelae to excavate the sand, whereas Cancer productus used the legs to pull and push itself down into the sediment only using the chelae in a final push beneath the sediment. Several individuals of each species remained buried for over 50 h, which was accomplished by alterations in ventilatory physiology. More commonly, both species exhibited an endogenous rhythm of circadian periodicity, with peak periods of emergence from the sand occurring during nocturnal high tides. Although burial may act as a means of predator evasion and to ambush prey, it appears the primary reason may be to conserve energy. These two species of crabs often occur sympatrically; the difference in behaviours is closely related to previously reported differences in physiological mechanisms between the two species when buried.

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-...

Near Infrared Activity Close to the Crab Pulsar Correlated with Giant Gamma-ray Flares

Science.gov (United States)

Rudy, Alexander R.; Max, Claire E.; Weisskopf, Martin C.

2014-01-01

We describe activity observed in the near-infrared correlated with a giant gamma-ray flare in the Crab Pulsar. The Crab Pulsar has been observed by the Fermi and AGILE satellites to flare for a period of 3 to 7 days, once every 1-1.5 years, increasing in brightness by a factor of 3-10 between 100MeV and 1GeV. We used Keck NIRC2 laser guide star adaptive optics imaging to observe the Crab Pulsar and environs before and during the March 2013 flare. We discuss the evidence for the knot as the location of the flares, and the theoretical implications of these observations. Ongoing target-of-opportunity programs hope to confirm this correlation for future flares.

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

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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

[Fishery and biometrics of genus Calappa crabs (Brachyura: Calappidae) in northeastern Venezuela].

Science.gov (United States)

Alió, José J; Marcano, Luis A; Altuve, Douglas E

2005-01-01

The box crabs, genus Calappa, are important crab species landed by the industrial trawl fleet in Venezuela. These crabs have a wide distribution in the country, from the Gulf of Venezuela to the Orinoco River, but major landings take place in such gulf, near Margarita Island and northern Sucre State. Average annual landing in the eastern region was 69 t during 1970-2001, with a maximum of 221 t. For this study a sample of 2 398 box crabs was collected by observers on board of industrial trawl vessels, which operated in eastern Venezuela from 1994 to 2000. Three species were found in the landings, Calappa sulcata and C. flammea. each represented 47% of the sample, and C. nitida, which accounted for 5% of the sample. Sex ratio was strongly biased towards males in C. sulcata (2.8:1) and in C. flammnea (1.9:1). while it was only slightly biased in C. nitida (1.4:1). Due to its large size, C. sulcuta is of great commercial interest, with average weight 290 g and a maximum weight of 720 g: C. flammea showed an average weight of 140 g and a maximum weight of 418 g, while C. nitida is the smallest species, with average weight 46 g and maximum weight not beyond 113 g. Box crabs were captured by day and night in similar proportions, and were found in a wide depth range, from a few meters to 126 m deep; however, the largest captures were obtained in the interval 38 - 54 m. Regressions between weight of chelae and total weight were linear, and significantly different between sexes. The relation between total weight and carapace width was allometric, with a power exponent ca. three in C. sulcata, and less than three in C. flamea and C. nitida. Females of C. sulcata and C. nitida showed power exponents significantly smaller than males. Since claws are removed from the animal to be commercialized, while the rest of the animal is returned alive to the sea, for practical purposes a common equation among species and sexes to convert claws weight into total body weight is: total

Food sources for the mangrove tree crab aratus pisonii: a carbon isotopic study

International Nuclear Information System (INIS)

Lacerda, L.D.; Silva, C.A.R.; Rezende, C.E.; Martinelli, L.A.

1991-01-01

Muscle tissues from the mangrove tree crab Aratus pisonii was analysed for carbon isotopic composition, in order to trace its major food sources. Potential food sources: mangrove leaves epi phytic green algae, mangrove sediments and open water and mangrove suspended matter; were also analysed. The results show that A. pisonii is basically omnivorous, with major food sources from marine origin. However, mangrove carbon can contribute with 16% to 42% in the crab's diet. (author)

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

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

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.

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.

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

Science.gov (United States)

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

2018-05-01

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

Abundance, breeding and growth of the ocypodid crab Dotilla myctiroides (Milne-Edwards) on a West Malaysian beach

Science.gov (United States)

Hails, A. J.; Yaziz, S.

1982-08-01

The ocypodid crab, Dotilla myctiroides, was studied on the south-west coast of peninsular Malaysia. The mean numbers and biomass over a year along a transect from high to low water ranged from 37·5 to 579 crabs m -2 and from 2·22 to 50·79 g m -2 (wet weight) respectively. Berried females were found in all months of the year but two peaks of activity were apparent, from November to February and May to July. It is suggested that this may be related to changes in food abundance associated with the effects of monsoon winds on sea currents. Laboratory growth studies indicated that maximum life span was approximately 13 months (from first crab stage) for males and 10 months for females. Growth rate decreased with increasing size of crab. Egg number increased with size of female.

Environmental colonization and onward clonal transmission of carbapenem-resistant Acinetobacter baumannii (CRAB) in a medical intensive care unit: the case for environmental hygiene.

Science.gov (United States)

Ng, Deborah H L; Marimuthu, Kalisvar; Lee, Jia Jun; Khong, Wei Xin; Ng, Oon Tek; Zhang, Wei; Poh, Bee Fong; Rao, Pooja; Raj, Maya Devi Rajinder; Ang, Brenda; De, Partha Pratim

2018-01-01

In May 2015, we noticed an increase in carbapenem-resistant Acinetobacter baumannii (CRAB) infections in the Medical Intensive Care Unit (MICU). To investigate this, we studied the extent of environmental contamination and subsequent onward clonal transmission of CRAB. We conducted a one-day point prevalence screening (PPS) of the patients and environment in the MICU. We screened patients using endotracheal tube aspirates and swabs from nares, axillae, groin, rectum, wounds, and exit sites of drains. We collected environmental samples from patients' rooms and environment outside the patients' rooms. CRAB isolates from the PPS and clinical samples over the subsequent one month were studied for genetic relatedness by whole genome sequencing (WGS). We collected 34 samples from seven patients and 244 samples from the environment. On the day of PPS, we identified 8 CRAB carriers: 3 who screened positive and 5 previously known clinical infections. We detected environmental contamination in nearly two-thirds of the rooms housing patients with CRAB. WGS demonstrated genetic clustering of isolates within rooms but not across rooms. We analysed 4 CRAB isolates from clinical samples following the PPS. One genetically-related CRAB was identified in the respiratory sample of a patient with nosocomial pneumonia, who was admitted to the MICU five days after the PPS. The extensive environmental colonization of CRAB by patients highlights the importance of environmental hygiene. The transmission dynamics of CRAB needs further investigation.

The Crab Hole Mosquito Blues

OpenAIRE

Johnson, Karl M.; Antczak, Douglas F.; Dietz, William H.; Martin, David H.; Walton, Thomas E.

2011-01-01

Venezuelan equine encephalomyelitis (VEE) epizoodemics were reported at 6–10-year intervals in northern South America beginning in the 1920s. In 1937, epizootic VEE virus was isolated from infected horse brain and shown as distinct from the North American equine encephalomyelitis viruses. Subsequently, epizootic and sylvatic strains were isolated in distinct ecosystems; isolates were characterized serologically as epizootic subtype I, variants A/B and C; or sylvatic (enzootic) subtype I, vari...

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

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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.

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.

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

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 (Sicily, Italy). The hard X-ray experiment (HXR 79) 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. (Auth.)

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

International Nuclear Information System (INIS)

Weiler, K.W.; Panagia, N.

1978-01-01

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

Cadmium in the shore crab Carcinus maenas along the Norwegian coast: geographical and seasonal variation and correlation to physiological parameters.

Science.gov (United States)

Knutsen, Heidi; Wiech, Martin; Duinker, Arne; Maage, Amund

2018-03-27

Previously, high concentrations of cadmium have been found in the hepatopancreas of the edible or brown crab (Cancer pagurus) sampled from positions north of about 67° N, compared to regions further south along the Norwegian coast, with no clear understanding why. In order to study a similar organism in the same ecosystem, the present study analyzed 210 shore crabs (Carcinus maenas) from four different locations along the Norwegian coast, two in the North and two in the South. The physiological variables size, sex, molting stage, hepatosomatic index, carapace color, and gonad maturation were registered, in attempt to explain the high inter-individual variation in cadmium levels in hepatopancreas. In contrast to the brown crabs, the shore crabs showed no clear geographical differences in cadmium concentrations. This indicates physiological differences between the two crab species. No clear and consistent correlations were found between cadmium levels and physiological parameters, except for sex, where cadmium concentration in hepatopancreas was twice as high in males compared to females. The cadmium levels also varied with season, with approximately 40 and 60% lower cadmium concentration in April than August for male and female shore crabs, respectively. None of the analyzed cadmium concentrations in muscle meat from claws exceeded EUs food safety limit, and low cadmium levels in soup prepared from shore crabs clearly indicated that this dish is not problematic regarding food safety.

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...

Effectiveness of artificial diet enriched by spinach extract on molting stimulation to produce soft shell crab

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Siti Aslamyah

2011-01-01

Full Text Available Artificial feed is an alternative media applications spinach extract (EB that is known to contain molting stimulant. However, utilization of the artificial feed is related to its expensive cost, with a very high protein concentration since it's mainly produced from fish based materials, so need to be studied artificial feed formulation with substitution of vegetable material in stimulating molting and growth of mud crabs. Four formula artificial feed enriched EB (700 ng/g crab used in this study were feed A (fish, crab shells, and cassava, feed B (fish, silage, shell crab, and cassava, feed C (fish, silage, shell crab, soy flour, and cassava, and feed D (fish, silage, shell crab, soy flour, corn starch, and pollard, trash fish and feed A without EB as control. During the test, mud crab intermolt phase was culture individually in crab box placed in pond. The results showed that the percentage of molting and weight growth in their respective in the feed A (44% and 41.96%; feed B (56% and 31.57%; feed C (74% and 23.20%; feed D (50% and 39.15%; trash feed control (24% and 50.66%; and feed A without EB (28% and 35.11%. An opposite phenomenon, where the feed C with the highest percentage of molting but with the lowest growth rate, the opposite occurs in the control of trash feed. This is apparently the effect of spinach extract as a stimulant molting, where performance can be optimized with a complete and balance nutrient composition. This prediction is supported by the analysis of protein content of crabs tested at the highest feed C treatment compared with the control feed. Key words: spinach extract, soft shell crab, molting, artificial feed, growth   ABSTRAK Pakan buatan merupakan alternatif media aplikasi ekstrak bayam (EB yang diketahui mengandung stimulan molting.  Namun demikian, pakan buatan yang digunakan masih mahal dengan kandungan protein yang tinggi, karena berbahan dasar ikan, sehingga perlu dikaji formulasi pakan buatan dengan

Particle acceleration in explosive relativistic reconnection events and Crab Nebula gamma-ray flares

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Lyutikov, Maxim; Komissarov, Serguei; Sironi, Lorenzo

2018-04-01

We develop a model of gamma-ray flares of the Crab Nebula resulting from the magnetic reconnection events in a highly magnetised relativistic plasma. We first discuss physical parameters of the Crab Nebula and review the theory of pulsar winds and termination shocks. We also review the principle points of particle acceleration in explosive reconnection events [Lyutikov et al., J. Plasma Phys., vol. 83(6), p. 635830601 (2017a); J. Plasma Phys., vol. 83(6), p. 635830602 (2017b)]. It is required that particles producing flares are accelerated in highly magnetised regions of the nebula. Flares originate from the poleward regions at the base of the Crab's polar outflow, where both the magnetisation and the magnetic field strength are sufficiently high. The post-termination shock flow develops macroscopic (not related to the plasma properties on the skin-depth scale) kink-type instabilities. The resulting large-scale magnetic stresses drive explosive reconnection events on the light-crossing time of the reconnection region. Flares are produced at the initial stage of the current sheet development, during the X-point collapse. The model has all the ingredients needed for Crab flares: natural formation of highly magnetised regions, explosive dynamics on the light travel time, development of high electric fields on macroscopic scales and acceleration of particles to energies well exceeding the average magnetic energy per particle.

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

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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

A Multifaceted Mass Spectrometric Method to Probe Feeding Related Neuropeptide Changes in Callinectes sapidus and Carcinus maenas

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Zhang, Yuzhuo; DeLaney, Kellen; Hui, Limei; Wang, Junhua; Sturm, Robert M.; Li, Lingjun

2018-05-01

Food intake is regulated by various neuromodulators, including numerous neuropeptides. However, it remains elusive at the molecular and cellular level as to how these important chemicals regulate internal processes and which regions of the neuronal organs are responsible for regulating the behavior. Here we report a comparative neuropeptidomic analysis of the brain and pericardial organ (PO) in response to feeding in two well-studied crustacean physiology model organisms, Callinectes sapidus and Carcinus maenas, using mass spectrometry (MS) techniques. A multifaceted MS-based approach has been developed to obtain complementary information on the expression changes of a large array of neuropeptides in the brain and PO. The method employs stable isotope labeling of brain and PO extracts for relative MS quantitation, capillary electrophoresis (CE)-MS for fractionation and high-specificity analysis, and mass spectrometric imaging (MSI) for in-situ molecular mapping of peptides. A number of neuropeptides, including RFamides, B-type allatostatins (AST-B), RYamides, and orcokinins exhibit significant changes in abundance after feeding in this investigation. Peptides from the AST-B family found in PO tissue were shown to have both altered expression and localization changes after feeding, indicating that they may be a class of vital neuropeptide regulators involved in feeding behavior. [Figure not available: see fulltext.

A Multifaceted Mass Spectrometric Method to Probe Feeding Related Neuropeptide Changes in Callinectes sapidus and Carcinus maenas

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Zhang, Yuzhuo; DeLaney, Kellen; Hui, Limei; Wang, Junhua; Sturm, Robert M.; Li, Lingjun

2018-02-01

Food intake is regulated by various neuromodulators, including numerous neuropeptides. However, it remains elusive at the molecular and cellular level as to how these important chemicals regulate internal processes and which regions of the neuronal organs are responsible for regulating the behavior. Here we report a comparative neuropeptidomic analysis of the brain and pericardial organ (PO) in response to feeding in two well-studied crustacean physiology model organisms, Callinectes sapidus and Carcinus maenas, using mass spectrometry (MS) techniques. A multifaceted MS-based approach has been developed to obtain complementary information on the expression changes of a large array of neuropeptides in the brain and PO. The method employs stable isotope labeling of brain and PO extracts for relative MS quantitation, capillary electrophoresis (CE)-MS for fractionation and high-specificity analysis, and mass spectrometric imaging (MSI) for in-situ molecular mapping of peptides. A number of neuropeptides, including RFamides, B-type allatostatins (AST-B), RYamides, and orcokinins exhibit significant changes in abundance after feeding in this investigation. Peptides from the AST-B family found in PO tissue were shown to have both altered expression and localization changes after feeding, indicating that they may be a class of vital neuropeptide regulators involved in feeding behavior. [Figure not available: see fulltext.

North Sea ecosystem change from swimming crabs to seagulls.

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

2012-10-23

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

CHINESE MITTEN CRABS (ERIOCHEIR SINENSIS) IN THE ST. LAWRENCE RIVER (CANADA): NEW RECORDS AND RISK OF INVASION

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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 ...

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

Science.gov (United States)

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

2013-10-01

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

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)

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

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Sabrina Angeletti

2015-07-01

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

Chaetotaxy and setal diversity of grooming legs in species of porcelain crabs (Crustacea: Anomura: Porcellanidae

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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.

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

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

2010-11-01

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 K(OW) 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. © 2010 SETAC.

[Proximal chemical composition and functional properties of fresh meat of crab claws (Homalaspis plana)].

Science.gov (United States)

Abugoch, L; Barrios, J; Guarda, A

1996-12-01

The research of alternative technological processes is being necessary in order to obtain a better utilization of hydrobiologic resources and food products, with higher added value. Crab (Homolaspis plana) is a crustacean found along the Chilean coast, whose flesh is exported as a frozen product. The resource crab is scantly studied in Chile and could became an excellent raw material for "delicatessen" products, with a high market value. The proximal composition, through the protein, fat, moisture and ashes content was determined. The non nitrogen extract was calculated by difference. The functional properties (water retention, emulsifying and gel-forming capacities) of fresh crab claws meat without additives were measured. The proximal composition for the claw meat was: 79,34 +/- 1.12% moisture, 16.75 +/- 1.29% protein, 1.86 +/- 0.11% ashes, 0.11 +/- 0.01 fat % and 1.93 +/- 1.07% N.N.E. In relation with the emulsifying capacity, claw meat was able to emulsify 2,259.03 +/- 73.04 g vegetal oil/g protein. The water retention was 154.49 +/- 6.85% representing the increase in mass percent; and the force of the gel formed in claw meat was 195.3 +/- 17.16 g-force x cm. According to these results, the claw crab is an attractive food, with a high protein and low fat content. Crab meat showed an excellent emulsifying capacity and water retention, so it can be used as a good raw material for the development of smearing products. In the case of gel-like products, further studies will be required, in order to optimize the conditions in which a stronger gel could be obtained.

Identification and characterization of the related immune-enhancing proteins in crab Scylla paramamosain stimulated with rhubarb polysaccharides.

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Cao, Jingsong; Wang, Zehuan; Zhang, Yueling; Qu, Fengliang; Guo, Lingling; Zhong, Mingqi; Li, Shengkang; Zou, Haiying; Chen, Jiehui; Wang, Xiuying

2014-02-01

Recently, considerable interest has been focused on immunostimulants to reduce diseases in crab aquaculture. However, information regarding to the related immune-enhancing proteins in crabs is not available yet. In this study, rhubarb polysaccharides were tested for enhancement of the immune activity in crab Scylla paramamosain. Compared with those in the control group, values of, phenoloxidase (PO), alkaline phosphatase (AKP) and alkaline phosphatasein (ACP) activity in the, experimental group were improved significantly 4 d after the treatment. Furthermore, 15 and 17 altered proteins from haemocytes and hepatopancreas, respectively, were found in rhubarb polysaccharide-treated crabs using 2-DE approach. Of these, hemocyanin, chymotrypsin, cryptocyanin, C-type lectin receptor, and ferritin protein were identified by mass spectrometry. In addition, RT-PCR, analysis showed that the mRNA levels of hemocyanin and chymotrypsin increased about 2.4- and 1.4-fold in the experiment group. Moreover, the hemocyanin gene in S. paramamosain (SpHMC) was, cloned and characterized. SpHMC contains one open reading frame of 2022 bp and encodes a polypeptide of 673 amino acids. It is clustered into one branch along with crab hemocyanin in a phylogenetic tree. The mRNA transcripts of SpHMC were detected mainly in the tissues of, hepatopancreas, hemocyte and intestines, and its levels were up-regulated significantly in hemocytes, of S. paramamosain treated with Vibrio parahemolyticus, Beta streptococcus or poly I:C for 6-48 h. Taken together, these studies found 5 related immune-enhancing proteins and a novel heomcyanin homologue with potential pathogen-resistant activities in crab. Copyright © 2013 Elsevier Ltd. All rights reserved.

Dungeness Crab Dredging Entrainment Studies in the Lower Columbia River, 2002 – 2004: Loss Projections, Salinity Model, and Scenario Analysis

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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.

78 FR 17341 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

Science.gov (United States)

2013-03-21

... Purchased. contracting custom processing must report. Raw pounds by crab fishery. Product and processes by... purchased (raw Purchased. pounds) by crab fishery. Custom processing services purchased (product and process... greatest information value to the management decision making process. The EDR is required to be submitted...

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

Science.gov (United States)

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

2017-07-01

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

Ontogenetic changes in the olfactory antennules of the shore crab, Hemigrapsus oregonensis, maintain sniffing function during growth.

Science.gov (United States)

Waldrop, Lindsay D; Hann, Miranda; Henry, Amy K; Kim, Agnes; Punjabi, Ayesha; Koehl, M A R

2015-01-06

Malacostracan crustaceans capture odours using arrays of chemosensory hairs (aesthetascs) on antennules. Lobsters and stomatopods have sparse aesthetascs on long antennules that flick with a rapid downstroke when water flows between the aesthetascs and a slow return stroke when water is trapped within the array (sniffing). Changes in velocity only cause big differences in flow through an array in a critical range of hair size, spacing and speed. Crabs have short antennules bearing dense arrays of flexible aesthetascs that splay apart during downstroke and clump together during return. Can crabs sniff, and when during ontogeny are they big enough to sniff? Antennules of Hemigrapsus oregonensis representing an ontogenetic series from small juveniles to adults were used to design dynamically scaled physical models. Particle image velocimetry quantified fluid flow through each array and showed that even very small crabs capture a new water sample in their arrays during the downstroke and retain that sample during return stroke. Comparison with isometrically scaled antennules suggests that reduction in aesthetasc flexural stiffness during ontogeny, in addition to increase in aesthetasc number and decrease in relative size, maintain sniffing as crabs grow. Sniffing performance of intermediate-sized juveniles was worse than for smaller and larger crabs. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

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

The accumulation, retention and distribution of 95mTc in crab (Cancer pagurus L.) and lobster (Homarus gammarus L.). A comparative study

International Nuclear Information System (INIS)

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

1988-01-01

The accumulation, retention and distribution of 95m Tc has been compared in lobsters and edible crabs kept under identical experimental conditions. The steady-state concentration factor (C ss ) for the uptake of 95m Tc from seawater was significantly greater for female crabs (C ss =17·9) than for males (C ss =14·4), whereas in lobsters there was no such sex difference and the C ss of 1161 was much greater than in crabs. The uptake of technetium from food (as indicated by whole body counts) was only moderately greater in lobsters than crabs. Retention of 95m Tc was similar for crabs and lobsters of both sexes but the clearance rate was greater after the nuclide had been taken up from seawater (t b1/2 =51 days) than from food (t b1/2 =108 days). In all crabs and most male lobsters 95m Tc was predominantly in the hepatopancreas while in a few male and all female lobsters it was mainly in muscle. Lobster ovaries consistently contained more activity than testes but this difference was not seen in crabs. In hepatopancreas cells of both species 95m Tc occurred mainly in the cytosol and some initial steps were taken to determine the relationship between technetium and cytosol proteins. The results for crab and lobster are compared with those from previous studies on these and other crustacean species. The possible basis for the much higher concentrations of technetium in lobsters than crabs is discussed and further research suggested. (Copyright (c) 1988 Elsevier Science B.V., Amsterdam. All rights reserved.)

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.

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

Responses of a Rocky Shore Gastropod to the Effluents of Predatory and Non-predatory Crabs: Avoidance and Attraction.

Science.gov (United States)

Marko, P B; Palmer, A R

1991-12-01

Laboratory experiments revealed that the rocky shore gastropod, Nucella lamellosa (Gmelin), could discriminate between the effluents of predatory and non-predatory crabs. N. lamellosa turned away from seawater that had passed over the large predatory crab, Cancer productus Randall. This avoidance behavior was observed in snails from two localities that, based on differences in shell form, presumably experienced different levels of predation intensity. The scent of the non-predatory crabs Pugettia producta (Randall) and Lopholithodes mandtii Brandt had no effect on the turning behavior of snails from either site. Surprisingly, snails from both sites were attracted to the scent of a small shore crab, Hemigrapsus nudus (Dana), but moved at random in response to a common prey item Balanus glandula Darwin. These results suggest that N. lamellosa can assess from a distance the relative risks posed by different species of crabs, and respond appropriately. The unexpected attraction to H. nudus suggests that N. lamellosa may use this effluent to home in from a distance on potential refugia, because H. nudus are often associated with crevices and the undersides of boulders where N. lamellosa would be less vulnerable to larger predators.

76 FR 60379 - Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab; Amendment 3

Science.gov (United States)

2011-09-29

.... 100903433-1531-02] RIN 0648-BA22 Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab... approved in Amendment 3 to the Atlantic Deep-Sea Red Crab Fishery Management Plan (FMP). The New England... ABC control rule.'' The NS1 guidelines further state that ``ABC may not exceed OFL,'' and that ``the...

Laboratory Studies on Molting and Growth of the Shore Crab, Hemigrapsus sanguineus de Haan, Parasitized by a Rhizocephalan Barnacle.

Science.gov (United States)

Takahashi, T; Matsuura, S

1994-06-01

Molting of shore crabs (Hemigrapsus sanguineus) parasitized by rhizocephalans (Sacculina senta) was observed in the laboratory, and the growth of the molted crabs was compared with that of unparasitized animals. Molting of the host was obstructed by the infestation, but was still possible. After the release of several broods of larvae, the externa (the external reproductive system of the parasite) detached from the host. Subsequent molting occurred within 40 days in about 80% of the animals, but in the remainder, it was delayed for at most 4 months. Soon after molting, a new externa protruded from the abdomen of every crab. Thus, the life-span of the externa and the molting of the host would seem to be closely connected. In the female, the molt frequency was reduced, but the molt increment of the parasitized crabs was not different from that in the unparasitized ones. In the male, however, both the molt frequency and the molt increment were reduced. Thus, the annual growth of parasitized males and females was about half that of unparasitized crabs.

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

Carapace surface architecture facilitates camouflage of the decorator crab Tiarinia cornigera.

Science.gov (United States)

Sanka, Immanuel; Suyono, Eko Agus; Rivero-Müller, Adolfo; Alam, Parvez

2016-09-01

This paper elucidates the unique setal morphology of the decorator crab Tiarinia cornigera, and further presents evidence to that setal morphology promotes micro-organism nucleation and adhesion. The carapace of this crab is covered by clusters of setae, each comprising a hollow acicular stem that is enveloped by a haystack-like structure. Using computational fluid dynamics, we find that these setae are responsible for manipulating water flow over the carapace surface. Micro-organisms in the sea water, nest in areas of flow stagnation and as a result, nucleate to and biofoul the setae by means of chemical adhesion. Attached micro-organisms secrete extracellular polymeric substances, which we deduce must also provide an additional element of chemical adhesion to mechanically interlocked mesoscopic and macroscopic biomatter. By coupling physical and chemical methods for adhesion, T. cornigera is able to hierarchically decorate its carapace. Our paper brings to light the unique decorator crab carapace morphology of T. cornigera; and furthermore evidences its function in micro-organism nucleation and adhesion. We show how this special carapace morphology directs and guides water flow to form nesting regions of water stagnation where micro-organisms can nucleate and adhere. In the literature, decorator crab carapaces are presumed to be able to mechanically interlock biomatter as camouflage using hook-like setal outgrowths. T. cornigera contrarily exhibits clusters of hay-stack like structures. By encouraging micro-organism adhesion to the carapace setae, T. cornigera is able to effectively attach biomatter using both chemical and physical principles of adhesion. T. cornigera essentially has a super-biofouling carapace surface, for at least micro-organisms. Our work will have an impact on researchers interested in biofouling, adhesion, biomedical and purification filter systems, and in the development of novel biomimetic surfaces with tailored properties. Copyright �

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

Science.gov (United States)

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

2018-01-01

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

[Adenosine triphosphatase activity in the organs of the crab Hemigrapsus sanguineus, acclimated to sea water of different salinity].

Science.gov (United States)

Busev, V M

1977-01-01

In crabs acclimated to low salinity, the activity of Na, K-ATPase from the gills increases; the activity also increases in the antennal glands after acclimation of the animals to high salinity. The activity of Na, K-ATPase in the abdominal ganglion and in the heart does not depend on the salinity to which crabs had been acclimated. Changes in the activity of Mg-ATPase in the gills and antennal glands associated with acclimation of crabs to sea water with different salinity correspond to those in the activity of Na, K-ATPase.

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.

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

Cryptic color change in a crab spider (Misumena vatia): identification and quantification of precursors and ommochrome pigments by HPLC.

Science.gov (United States)

Riou, Mickaël; Christidès, Jean-Philippe

2010-04-01

Mimicry is used widely by arthropods to survive in a hostile environment. Often mimicry is associated with the production of chemical compounds such as pigments. In crab spiders, the change of color is based on a complex physiological process that still is not understood. The aim of this study was to identify and quantify the ommochrome pigments and precursors responsible for the color change in the mimetic crab spider Misumena vatia (Thomisidae). A modified high performance reverse phase ion-pair chromatography technique enabled us to separate and quantify the ommochrome pigments, their precursors, and related metabolites in individual spiders. Compounds such as tryptophan, kynurenine, and kynurenic acid occurred only or mainly in white crab spiders. In contrast, compounds such as 3-hydroxy-kynurenine, xanthommatin, and ommatin D occurred only or mainly in yellow crab spiders. Factor analysis ranked the different color forms in accordance with their metabolites. The biochemical results enabled us to associate the different phases of formation of pigment granules with specific metabolites. Yellow crab spiders contain many unknown ommochrome-like compounds not present in white crab spiders. We also found large quantities of decarboxylated xanthommatin, whose role as precursor of new pathways in ommochrome synthesis needs to be assessed. The catabolism of ommochromes, a process occurring when spiders revert from yellow to white, warrants further study.

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

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.

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.

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

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.

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)

75 FR 27219 - Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab Fisheries; 2010 Atlantic...

Science.gov (United States)

2010-05-14

.... Whereas a limited market has been responsible for the shortfall in landings compared to the target TAC... final specifications for the 2010 Atlantic deep- sea red crab fishery, including a target total... specify the target TAC and other management measures in order to manage the red crab resource for fishing...

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

Digital Repository Service at National Institute of Oceanography (India)

Chatterji, A.; Parulekar, A.H.

and per g ovary weight were 48, 18 and 164 respectively. Maximum fecundity was observed in crabs ranging in size from 174-179 mm. Relationships between fecundity, carapace length, body weight and ovary weight were linear...

The accumulation, retention and distribution of {sup 95m}Tc in crab (Cancer pagurus L.) and lobster (Homarus gammarus L.). A comparative study

Energy Technology Data Exchange (ETDEWEB)

Smith, D L; Knowles, J F; Winpenny, K [The Centre for Environment, Fisheries and Aquaculture Science, Lowestoft Laboratory, Pakefield Road, Lowestoft, Suffolk (United Kingdom)

1988-08-01

The accumulation, retention and distribution of {sup 95m}Tc has been compared in lobsters and edible crabs kept under identical experimental conditions. The steady-state concentration factor (C{sub ss}) for the uptake of {sup 95m}Tc from seawater was significantly greater for female crabs (C{sub ss}=17{center_dot}9) than for males (C{sub ss}=14{center_dot}4), whereas in lobsters there was no such sex difference and the C{sub ss} of 1161 was much greater than in crabs. The uptake of technetium from food (as indicated by whole body counts) was only moderately greater in lobsters than crabs. Retention of {sup 95m}Tc was similar for crabs and lobsters of both sexes but the clearance rate was greater after the nuclide had been taken up from seawater (t{sub b1/2}=51 days) than from food (t{sub b1/2}=108 days). In all crabs and most male lobsters {sup 95m}Tc was predominantly in the hepatopancreas while in a few male and all female lobsters it was mainly in muscle. Lobster ovaries consistently contained more activity than testes but this difference was not seen in crabs. In hepatopancreas cells of both species {sup 95m}Tc occurred mainly in the cytosol and some initial steps were taken to determine the relationship between technetium and cytosol proteins. The results for crab and lobster are compared with those from previous studies on these and other crustacean species. The possible basis for the much higher concentrations of technetium in lobsters than crabs is discussed and further research suggested. (Copyright (c) 1988 Elsevier Science B.V., Amsterdam. All rights reserved.)

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

Science.gov (United States)

2010-07-23

... of a 2.67-percent fee for cost recovery under the Bering Sea and Aleutian Islands Crab... for the 2010/2011 crab fishing year so they can calculate the required payment for cost recovery fees...-Stevens Act). The Program includes a cost recovery provision to collect fees to recover the actual costs...

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

Science.gov (United States)

2013-08-01

... of a 0.69-percent fee for cost recovery under the Bering Sea and Aleutian Islands Crab... for the 2013/2014 crab fishing year so they can calculate the required payment for cost recovery fees... Program includes a cost recovery provision to collect fees to recover the actual costs directly related to...

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

Science.gov (United States)

2011-07-21

... of a 1.23-percent fee for cost recovery under the Bering Sea and Aleutian Islands Crab... for the 2011/2012 crab fishing year so they can calculate the required payment for cost recovery fees...-Stevens Act). The Program includes a cost recovery provision to collect fees to recover the actual costs...

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

African Journals Online (AJOL)

SARAH

2015-12-31

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

Identification of a serine proteinase homolog (Sp-SPH) involved in immune defense in the mud crab Scylla paramamosain.

Science.gov (United States)

Zhang, Qiu-xia; Liu, Hai-peng; Chen, Rong-yuan; Shen, Kai-li; Wang, Ke-jian

2013-01-01

Clip domain serine proteinase homologs are involved in many biological processes including immune response. To identify the immune function of a serine proteinase homolog (Sp-SPH), originally isolated from hemocytes of the mud crab, Scylla paramamosain, the Sp-SPH was expressed recombinantly and purified for further studies. It was found that the Sp-SPH protein could bind to a number of bacteria (including Aeromonas hydrophila, Escherichia coli, Staphylococcus aureus, Vibrio fluvialis, Vibrio harveyi and Vibrio parahemolyticus), bacterial cell wall components such as lipopolysaccharide or peptidoglycan (PGN), and β-1, 3-glucan of fungus. But no direct antibacterial activity of Sp-SPH protein was shown by using minimum inhibitory concentration or minimum bactericidal concentration assays. Nevertheless, the Sp-SPH protein was found to significantly enhance the crab hemocyte adhesion activity (paired t-test, Pparahemolyticus which were both recognized by Sp-SPH protein, if pre-incubated with Sp-SPH protein, respectively. Whereas, the crabs died much faster when challenged with Vibrio alginolyiicus, a pathogenic bacterium not recognized by Sp-SPH protein, compared to those of crabs challenged with A. hydrophila or V. parahemolyticus when pre-coated with Sp-SPH protein. Taken together, these data suggested that Sp-SPH molecule might play an important role in immune defense against bacterial infection in the mud crab S. paramamosain.

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

International Nuclear Information System (INIS)

Satogata, Todd J.; Morozov, Vasiliy; Delayen, Jean R.; Castillo, Alejandro

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.

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.

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...

Spatial distribution of juvenile and adult female Tanner crabs (Chionoecetes bairdi) in a glacial fjord ecosystem: Implications for recruitment processes

Science.gov (United States)

Nielsen, J.K.; Taggart, S. James; Shirley, Thomas C.; Mondragon, Jennifer

2007-01-01

A systematic pot survey in Glacier Bay, Alaska, was conducted to characterize the spatial distribution of juvenile and adult female Tanner crabs, and their association with depth and temperature. The information was used to infer important recruitment processes for Tanner crabs in glaciated ecosystems. High-catch areas for juvenile and adult female Tanner crabs were identified using local autocorrelation statistics. Spatial segregation by size class corresponded to features in the glacial landscape: high-catch areas for juveniles were located at the distal ends of two narrow glacial fjords, and high-catch areas for adults were located in the open waters of the central Bay. Juvenile female Tanner crabs were found at nearly all sampled depths (15–439 m) and temperatures (4–8°C), but the biggest catches were at depths <150 m where adults were scarce. Because adults may prey on or compete with juveniles, the distribution of juveniles could be influenced by the distribution of adults. Areas where adults or predators are scarce, such as glacially influenced fjords, could serve as refuges for juvenile Tanner crabs.

Analysis and control of wakefields in X-band crab cavities for Compact Linear Collider

Energy Technology Data Exchange (ETDEWEB)

Ambattu, P.K., E-mail: praveen-kumar.ambattu@stfc.ac.uk [Cockcroft Institute, Warrington WA4 4AD (United Kingdom); Lancaster University, Lancaster LA1 4 YW (United Kingdom); Burt, G. [Cockcroft Institute, Warrington WA4 4AD (United Kingdom); Lancaster University, Lancaster LA1 4 YW (United Kingdom); Khan, V.F.; Jones, R.M. [Cockcroft Institute, Warrington WA4 4AD (United Kingdom); University of Manchester, Manchester M13 9PL (United Kingdom); Dexter, A. [Cockcroft Institute, Warrington WA4 4AD (United Kingdom); Lancaster University, Lancaster LA1 4 YW (United Kingdom); Dolgashev, V. [SLAC, Menlo Park, CA 94025 (United States)

2011-11-21

The Compact Linear Collider requires a crab cavity on each beamline prior to the interaction point to rotate the bunches before collision. The cavities are X-band travelling wave type and are located close to the final doublet of the beam delivery system. This makes the beam very sensitive to transverse momentum imparted by wakefields; hence the wakefields must be tightly controlled. Of special concerns are the orthogonal polarisation of the operating mode and the fundamental monopole mode of the crab cavity. The former mode is at the same frequency as the operating mode of a cylindrically symmetric cavity and the latter one is at a lower frequency and hence is difficult to damp using a single means. In this paper major problematic modes of the crab cavity are investigated and damping requirements for them are calculated. Possibility of meeting the required wakefield control using waveguide damping and choke damping is thoroughly investigated. As a comparison, damped-detuning is also investigated.

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

Trade-off between increased survival and reduced growth for blue mussels living on Pacific oyster reefs

DEFF Research Database (Denmark)

Eschweiler, Nina; Christensen, Helle Torp

2011-01-01

Pacific oysters Crassostrea gigas (Thunberg 1793) have been introduced into the Wadden Sea (North Sea, Germany) in the mid of the 1980s and have invaded native blue mussel Mytilus edulis (L.) beds. The latter turned into oyster reefs where mussels seem to be relegated to the bottom in between...... the much larger oysters. By combining field and laboratory experiments, we reveal how mussels react to cohabitation with the invasive oysters. Mussels subjected to direct contact with crabs Carcinus maenas migrate from top to bottom positions between oysters in both field and laboratory experiments within...... 22days. Shell growth was significantly reduced for mussels placed on the bottom compared to mussels at the top of an oyster reef. Condition index was lower for mussels on the bottom of the reef irrespective of whether placed between dead or living oysters. We conclude that mussels experience a trade...

Crab Cavity effects on transverse distribution evolution and tail cleaning in the HL-LHC

CERN Document Server

Baudrenghien, Philippe; Steeper, S; Tucker, D; Wieker, Devin; CERN. Geneva. ATS Department

2018-01-01

This work presents the transverse action and tune distribution evolution as a function of the Crab Cavity RF noise Power Spectral Density (PSD). In addition, it presents the potential for transverse tail cleaning through the deliberate injection of noise with an appropriate PSD. Such a procedure would be very beneficial since it would strongly reduce the transverse losses following a crab cavity trip, and could complement or substitute the electron lens approach.

Effects of metal contamination in situ on osmoregulation and oxygen consumption in the mudflat fiddler crab Uca rapax (Ocypodidae, Brachyura).

Science.gov (United States)

Capparelli, Mariana V; Abessa, Denis M; McNamara, John C

2016-01-01

The contamination of estuaries by metals can impose additional stresses on estuarine species, which may exhibit a limited capability to adjust their regulatory processes and maintain physiological homeostasis. The mudflat fiddler crab Uca rapax is a typical estuarine crab, abundant in both pristine and contaminated areas along the Atlantic coast of Brazil. This study evaluates osmotic and ionic regulatory ability and gill Na(+)/K(+)-ATPase activity in different salinities (Rio Itapanhaú, Bertioga>Picinguaba, Ubatuba [pristine reference site]). Our findings show that the contamination of U. rapax by metals in situ leads to bioaccumulation and induces biochemical and physiological changes compared to crabs from the pristine locality. U. rapax from the contaminated sites exhibit stronger hyper- and hypo-osmotic regulatory abilities and show greater gill Na(+)/K(+)-ATPase activities than crabs from the pristine site, revealing that the underlying biochemical machinery can maintain systemic physiological processes functioning well. However, oxygen consumption, particularly at elevated temperatures, decreases in crabs showing high bioaccumulation titers but increases in crabs with low/moderate bioaccumulation levels. These data show that U. rapax chronically contaminated in situ exhibits compensatory biochemical and physiological adjustments, and reveal the importance of studies on organisms exposed to metals in situ, particularly estuarine invertebrates subject to frequent changes in natural environmental parameters like salinity and temperature. Copyright © 2016. Published by Elsevier Inc.

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.

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

Digital Repository Service at National Institute of Oceanography (India)

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

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

Chandra Discovers X-Ray Ring Around Cosmic Powerhouse in Crab Nebula

Science.gov (United States)

1999-09-01

After barely two months in space, NASA's Chandra X-ray Observatory has taken a stunning image of the Crab Nebula, the spectacular remains of a stellar explosion, and has revealed something never seen before: a brilliant ring around the nebula's heart. Combined with observations from the Hubble Space Telescope, the image provides important clues to the puzzle of how the cosmic "generator," a pulsing neutron star, energizes the nebula, which still glows brightly almost 1,000 years after the explosion. "The inner ring is unique," said Professor Jeff Hester of Arizona State University, Tempe, AZ. "It has never been seen before, and it should tell us a lot about how the energy from the pulsar gets into the nebula. It's like finding the transmission lines between the power plant and the light bulb." Professor Mal Ruderman of Columbia University, New York, NY, agreed. "The X-rays Chandra sees are the best tracer of where the energy is. With images such as these, we can directly diagnose what is going on." What is going on, according to Dr. Martin Weisskopf, Chandra Project Scientist from NASA's Marshall Space Flight Center, Huntsville, AL, is awesome. "The Crab pulsar is accelerating particles up to the speed of light and flinging them out into interstellar space at an incredible rate." The image shows tilted rings or waves of high-energy particles that appear to have been flung outward over the distance of a light year from the central star, and high-energy jets of particles blasting away from the neutron star in a direction perpendicular to the spiral. Hubble Space Telescope images have shown moving knots and wisps around the neutron star, and previous X-ray images have shown the outer parts of the jet and hinted at the ring structure. With Chandra's exceptional resolution, the jet can be traced all the way in to the neutron star, and the ring pattern clearly appears. The image was made with Chandra's Advanced CCD Imaging Spectrometer and High Energy Transmission

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…

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...

Characterize and Gene Expression of Heat Shock Protein 90 in Marine Crab Charybdis japonica following Bisphenol A and 4-Nonylphenol Exposures.

Science.gov (United States)

Park, Kiyun; Kwak, Ihn-Sil

2014-01-01

Heat shock protein 90 (HSP90) is a highly conserved molecular chaperone important in the maturation of a broad spectrum of protein. In this study, an HSP90 gene was isolated from Asian paddle crab, Charybdis japonica, as a bio-indicator to monitor the marine ecosystem. This work reports the responses of C. japonica HSP90 mRNA expression to cellular stress by endocrine disrupting chemicals (EDCs), such as bisphenol A (BPA) and 4-nonylphenol (NP) using real-time. reverse transcription polymerase chain reaction. The deduced amino acid sequence of HSP90 from C. japonica shared a high degree of homology with their homologues in other species. In a phylogenetic analysis, C. japonica HSP90 is evolutionally related with an ortholog of the other crustacean species. The expression of HSP90 gene was almost distributed in all the examined tissues of the C. japonica crab but expression levels varied among the different body parts of the crabs. We examined HSP90 mRNA expression pattern in C. japonica crabs exposed to EDCs for various exposure times. The expression of HSP90 transcripts was significantly increased in C. japonica crabs exposed to BPA and NP at different concentrations for 12, 24, 48 and 96 hours. The mRNA expression of HSP90 gene was significantly induced in a concentration- and time-dependent manner after BPA or NP exposures for 96 hours. Taken together, expression analysis of Asian paddle crab HSP90 gene provided useful molecular information about crab responses in stress conditions and potential ways to monitor the EDCs stressors in marine environments.

Warming and pCO2 effects on Florida stone crab larvae

Science.gov (United States)

Gravinese, Philip M.; Enochs, Ian C.; Manzello, Derek P.; van Woesik, Robert

2018-05-01

Greenhouse gas emissions are increasing ocean temperatures and the partial pressure of CO2 (pCO2), resulting in more acidic waters. It is presently unknown how elevated temperature and pCO2 will influence the early life history stages of the majority of marine coastal species. We investigated the combined effect of elevated temperature (30 °C control and 32 °C treatment) and elevated pCO2 (450 μatm control and 1100 μatm treatment) on the (i) growth, (ii) survival, (iii) condition, and (iv) morphology of larvae of the commercially important Florida stone crab, Menippe mercenaria. At elevated temperature, larvae exhibited a significantly shorter molt stage, and elevated pCO2 caused stage-V larvae to delay metamorphosis to post-larvae. On average, elevated pCO2 resulted in a 37% decrease in survivorship relative to the control; however the effect of elevated temperature reduced larval survivorship by 71%. Exposure to both elevated temperature and pCO2 reduced larval survivorship by 80% relative to the control. Despite this, no significant differences were detected in the condition or morphology of stone crab larvae when subjected to elevated temperature and pCO2 treatments. Although elevated pCO2 could result in a reduction in larval supply, future increases in seawater temperatures are even more likely to threaten the future sustainability of the stone-crab fishery.

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.

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

Science.gov (United States)

Daniel. T. Jennings; Bruce Cutler

1996-01-01

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

Proximate causes of sexual size dimorphism in horseshoe crabs (Limulus Polyphemus) of the Delaware Bay

Science.gov (United States)

Smith, D.R.; Mandt, M.T.; Macdonald, P.D.M.

2009-01-01

The unresolved status of the proximate cause for sexual size dimorphism in horseshoe crabs has practical consequence, because harvest recommendations rely on assumptions about sex-specific growth and maturity. We propose and evaluate competing hypotheses for the proximate cause of sexual size dimorphism in horseshoe crabs (Limulus polyphemus) by comparing size and estimated age frequencies from spring-captured juveniles (n = 9,075) and adults (n = 36,274) to predictions from the competing hypotheses. We found that the number of identifiable juvenile size distributions was greater for females than males and the probability of remaining a juvenile was higher for females than males among older juveniles. These findings are consistent with males maturing earlier than females. Molt increments and mean sizes were similar for male and female juveniles, which is not consistent with differential growth. Among adults, one size distribution accounted for ???90% of females regardless of carapace wear. Also, size ratio of adult females to males was 1.26, and size ratio of the largest adult to largest juvenile female was 1.28. These observations are not consistent with females continuing to molt as adults. Differential-maturity is the most parsimonious explanation for sexual size dimorphism in Delaware Bay horseshoe crabs. In addition, because of a low frequency of juvenile females >195 mm relative to adult females and male-biased sex ratios starting at 105 mm, we hypothesize that females, more than males, migrate as older juveniles and mature in the ocean. Management implications include that (1) minimum size limits, as previously suggested, would not allocate harvest to older adults as intended because size does not indicate age among adult horseshoe crabs in the Delaware Bay population, and (2) the Shuster Horseshoe Crab Reserve, which has reduced harvest on the continental shelf, could be protecting older juveniles and newly mature females from harvest prior to their first

Inter-annual dynamics of the Barents Sea red king crab (Paralithodes camtschaticus) stock indices in relation to environmental factors

Science.gov (United States)

Dvoretsky, Alexander G.; Dvoretsky, Vladimir G.

2016-12-01

Knowledge of relationships between environmental variables and biological processes can greatly improve fisheries assessment and management in commercially important species. We analyzed the effects of environmental factors (climatic indices and water temperature) on the stock characteristics (total population number, number of pre-recruits and number of legal males) of the red king crab (Paralithodes camtschaticus), an introduced species in the Barents Sea. Stock trends in red king crab appear to be related to decadal climate shifts. Abundances were negatively related to the North Atlantic Oscillation index (NAO) in August and positively related to water temperature in late winter-early summer. Total and commercial stock abundance were negatively correlated with the lag-1 Arctic Oscillation index (AO) in August and the lag-2 winter NAO index. The total number of P. camtschaticus was most strongly associated with water temperature in spring and summer and NAO/AO indices in April and May. Lagged NAO indices in February and August (9 or 10 yr) had a positive relationship to the commercial stock of P. camtschaticus. These findings suggest that temperature conditions of current and previous year affect natural mortality of larvae and juvenile red king crabs. Warmer temperature conditions lead to increased biomass of red king crab food items. Negative correlations between climatic indices and the red king crab stocks may be associated with predator pressure on juvenile red king crabs or higher mortality because of predator or parasite pressure and diseases. The associations between stock indices and environmental variables could help better predict recruitment patterns of P. camtschaticus.

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

Identification of a Serine Proteinase Homolog (Sp-SPH) Involved in Immune Defense in the Mud Crab Scylla paramamosain

Science.gov (United States)

Zhang, Qiu-xia; Liu, Hai-peng; Chen, Rong-yuan; Shen, Kai-li; Wang, Ke-jian

2013-01-01

Clip domain serine proteinase homologs are involved in many biological processes including immune response. To identify the immune function of a serine proteinase homolog (Sp-SPH), originally isolated from hemocytes of the mud crab, Scylla paramamosain, the Sp-SPH was expressed recombinantly and purified for further studies. It was found that the Sp-SPH protein could bind to a number of bacteria (including Aeromonas hydrophila, Escherichia coli, Staphylococcus aureus, Vibrio fluvialis, Vibrio harveyi and Vibrio parahemolyticus), bacterial cell wall components such as lipopolysaccharide or peptidoglycan (PGN), and β-1, 3-glucan of fungus. But no direct antibacterial activity of Sp-SPH protein was shown by using minimum inhibitory concentration or minimum bactericidal concentration assays. Nevertheless, the Sp-SPH protein was found to significantly enhance the crab hemocyte adhesion activity (paired t-test, Pparahemolyticus which were both recognized by Sp-SPH protein, if pre-incubated with Sp-SPH protein, respectively. Whereas, the crabs died much faster when challenged with Vibrio alginolyiicus, a pathogenic bacterium not recognized by Sp-SPH protein, compared to those of crabs challenged with A. hydrophila or V. parahemolyticus when pre-coated with Sp-SPH protein. Taken together, these data suggested that Sp-SPH molecule might play an important role in immune defense against bacterial infection in the mud crab S. paramamosain. PMID:23724001

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...

Mavi Yengecin (Callinectes Sapidus Rathbun 1896 Et Verimi ve Besin Madde İçeriği Üzerine bir Araştırma

Directory of Open Access Journals (Sweden)

Hasan H. Atar

2015-02-01

Full Text Available Bu araştırmada, mavi yengecin (Callinectes sapiduset verimi ile etinin kuru madde, su, ham protein, ham yağ ve ham kül gibi besin maddelerinin belirlenmesi amaçlanmıştır. Mavi yengecin canlı ağırlık ortalaması 128.044±10.71 g, ortalama toplam et miktarı 24.365±2.25 g ve toplam et verimi % 23.060 olarak saptanmıştır. Besin maddeleri ile ilgili analiz sonuçlarına göre; mavi yengecin etinde ortalama su, kuru madde, ham protein, ham yağ, ham kül, kalsiyum ve fosfor oranları kıskaçta sırasıyla %77.40, % 22.60, %17.60, % 0.22, % 3.20, %0.20, %0.18 ve abdomende sırasıyla %77.80, %22.20, %17.50, %2.40, %0.37, %0.09, % 0.04 olarak tespit edilmiştir.

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.

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.

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

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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.

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 runaway stars.

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.

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 ...

Antioxidative-related genes expression following perfluorooctane sulfonate (PFOS) exposure in the intertidal mud crab, Macrophthalmus japonicus

Science.gov (United States)

Park, Kiyun; Nikapitiya, Chamilani; Kwak, Tae-Soo; Kwak, Ihn-Sil

2015-09-01

Perfluorooctane sulfonate (PFOS) is a persistent environmental contaminant that is used as a surfactant in various industries and consumer products. The intertidal mud crab, Macrophthalmus japonicus, is one of the most abundant macrobenthic creatures. In this study, we have investigated the effect of PFOS on the molecular transcription of antioxidant and detoxification signaling in M. japonicus crab. The selected stress response genes were superoxide dismutases (CuZnSOD and MnSOD), catalase (CAT), glutathione peroxidase (GPx), phospholipid hydroperoxide glutathione peroxidase (PHGPx), peroxiredoxin (Prx), and thioredoxin reductase (TrxR). Significant up-regulation of SODs and CAT was observed after 24 and 96 h exposure to PFOS at different concentrations. The gene expression levels of GPx, PHGPx, and TrXR were significantly up-regulated after exposure to PFOS for 96 h. The transcript levels of CAT and PHGPx were induced in dose- and time-dependent manners after PFOS treatments. However, Prx gene expression was significantly up-regulated in M. japonicus crabs exposed to 10 and 30 μg L-1 PFOS for 96 h. Additionally, PFOS toxicity in M. japonicus induced reduced survival rates at relatively high concentrations of PFOS exposure. Our findings support the contention that exposures to PFOS induced the response of genes related to oxidative stress and detoxification in M. japonicus crabs.

Dancing for food in the deep sea: bacterial farming by a new species of Yeti crab.

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Andrew R Thurber

Full Text Available Vent and seep animals harness chemosynthetic energy to thrive far from the sun's energy. While symbiont-derived energy fuels many taxa, vent crustaceans have remained an enigma; these shrimps, crabs, and barnacles possess a phylogenetically distinct group of chemosynthetic bacterial epibionts, yet the role of these bacteria has remained unclear. We test whether a new species of Yeti crab, which we describe as Kiwa puravida n. sp, farms the epibiotic bacteria that it grows on its chelipeds (claws, chelipeds that the crab waves in fluid escaping from a deep-sea methane seep. Lipid and isotope analyses provide evidence that epibiotic bacteria are the crab's main food source and K. puravida n. sp. has highly-modified setae (hairs on its 3(rd maxilliped (a mouth appendage which it uses to harvest these bacteria. The ε- and γ- proteobacteria that this methane-seep species farms are closely related to hydrothermal-vent decapod epibionts. We hypothesize that this species waves its arm in reducing fluid to increase the productivity of its epibionts by removing boundary layers which may otherwise limit carbon fixation. The discovery of this new species, only the second within a family described in 2005, stresses how much remains undiscovered on our continental margins.

Dancing for food in the deep sea: bacterial farming by a new species of Yeti crab.

Science.gov (United States)

Thurber, Andrew R; Jones, William J; Schnabel, Kareen

2011-01-01

Vent and seep animals harness chemosynthetic energy to thrive far from the sun's energy. While symbiont-derived energy fuels many taxa, vent crustaceans have remained an enigma; these shrimps, crabs, and barnacles possess a phylogenetically distinct group of chemosynthetic bacterial epibionts, yet the role of these bacteria has remained unclear. We test whether a new species of Yeti crab, which we describe as Kiwa puravida n. sp, farms the epibiotic bacteria that it grows on its chelipeds (claws), chelipeds that the crab waves in fluid escaping from a deep-sea methane seep. Lipid and isotope analyses provide evidence that epibiotic bacteria are the crab's main food source and K. puravida n. sp. has highly-modified setae (hairs) on its 3(rd) maxilliped (a mouth appendage) which it uses to harvest these bacteria. The ε- and γ- proteobacteria that this methane-seep species farms are closely related to hydrothermal-vent decapod epibionts. We hypothesize that this species waves its arm in reducing fluid to increase the productivity of its epibionts by removing boundary layers which may otherwise limit carbon fixation. The discovery of this new species, only the second within a family described in 2005, stresses how much remains undiscovered on our continental margins.

Intraspecific shape variation in horseshoe crabs: the importance of sexual and natural selection for local adaptation

DEFF Research Database (Denmark)

Faurby, Søren; Nielsen, Kasper Sauer Kollerup; Bussarawit, Somchai

2011-01-01

. Differences in shape variation between sexes were tested with F-tests, which showed lower intrapopulation morphometric variation in males than females. These results indicate a lower degree of local adaptation on body shape in C. rotundicauda and T. gigas than in L. polyphemus and a lower degree of local......A morphometric analysis of the body shape of three species of horseshoe crabs was undertaken in order to infer the importance of natural and sexual selection. It was expected that natural selection would be most intense, leading to highest regional differentiation, in the American species Limulus...... polyphemus, which has the largest climatic differences between different populations. Local adaptation driven by sexual selection was expected in males but not females because horseshoe crab mating behaviour leads to competition between males, but not between females. Three hundred fifty-nine horseshoe crabs...

Effects of visual and chemical cues on orientation behavior of the Red Sea hermit crab Clibanarius signatus

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Tarek Gad El-Kareem Ismail

2012-03-01

Full Text Available Directional orientation of Clibanarius signatus toward different targets of gastropod shells was studied in a circular arena upon exposure to background seawater, calcium concentrations and predatory odor. Directional orientation was absent when crabs were presented with the white background alone. Each shell was tested in different positions (e.g., anterior, posterior, upside-down, lateral. Adult crabs were tested without their gastropod shells, and orientation varied with concentration and chemical cue. With calcium, orientation increased as concentration increased up to a maximum attraction percentage and then attraction became stable. In the case of predator cues, some individuals swim away from the target toward the opposite direction representing a predator avoidance response. Whenever, the blind hermit crab C. signatus was exposed to a shell target combined with calcium or predator cues, the majority of them stop moving or move in circles around the arena center. The others exhibited uniform orientation distribution. The responsiveness was higher with calcium cues than predator cues. Thus in the absence of vision, individual hermit crabs were able to detect both calcium and predator cues and have different response regarding them.

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

Science.gov (United States)

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

2014-09-01

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

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

African Journals Online (AJOL)